[PATCH v8 0/8] Device Tree Overlays - 8th time's the charm

[PATCH v8 0/8] Device Tree Overlays - 8th time's the charm

[Pantelis Antoniou]

The following patchset introduces Device Tree overlays, a method
of dynamically altering the kernel's live Device Tree, along with
a generic interface to use it in a board agnostic manner.

It is against linux mainline as of today 28/10/2014
"f7e87a44ef60ad379e39b45437604141453bf0ec"
Merge tag 'media/v3.18-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media

It relies on the following previously submitted patches/patchsets:

* configfs: Implement binary attributes (v2)

To compile overlays you need the DTC compiler patch

* "dtc: Dynamic symbols & fixup support (v3)"

The full patchset is applied to the following tree/branch:

git:    git-9UaJU3cA/F/QT0dZR+AlfA@public.gmane.org:pantoniou/linux-beagle-track-mainline.git
branch: dt-ng/bbb
http:   https://github.com/pantoniou/linux-beagle-track-mainline/tree/dt-ng4/gcl-bbb

Changes since V7:
* Using the mainline resolver with the updated local fixups format.
* Drop delete capability using '-' prefix. The '-' prefixed names
are valid properties and nodes and there is no need for it just yet.
* Do not update special properties - name & phandle ones.
* Change order of node attachment, so that the special property update
works.

Changes since V6:
* Now using the updated transaction API.

Changes since V5:
* Rely on transactions for affecting changes to the live tree.
This makes the patchset considerably smaller, and easier to grok.
* Removed the internal API, simplyfing the interface.

Changes since V4:
* New API of_overlay_create/destroy being able to support stacked
overlays correctly.
* Removed use of notifiers internally.
* Removed own-grown bus handler notifiers; using already in-place DT
notification infrastructure.
* Split SPI notifier patch to one patch of generic changes and one
for DT overlay notifier.
* Removed unused overlay depth feature.
* Updated documentation.
* Moved configfs based interface to using the new API.
* Added overlay removal stacking tests.

Changes since V3:
* Added overlay self-tests.
* Fix bug in of_init_overlay_info (wrong sizeof)
* Platform bus handler handles parent_pdev == NULL
* of_resolve fixes according to comments by robh
 + changed if (foo == NULL) to if (!foo)
 + changed if (foo != NULL) to if (foo)
 + drivers/of/Kconfig added dep on OF && !SPARC
 + convert to using be32_to_cpup
 + u32 -> __be32 when modifying property values
 + cosmetic fixes

Changes since V2:
* Use of a configfs board agnostic overlay method
* Use of per bus handlers instead of hardcoded behaviour
* Optional target-path overlay target, which allows one to use standard
DTBs without resolution options.

Changes since V1:

* Removal of any bits related to a specific board (beaglebone).
* Introduced a platform agnostic interface using /proc/device-tree-overlay
* Various bug fixes related to i2c device handling have been squashed in.

Pantelis Antoniou (9):
 OF: Introduce Device Tree resolve support.
 OF: Introduce DT overlay support.
 OF: selftest: Add overlay self-test support.
 OF: DT-Overlay configfs interface
 OF: platform: Add OF notifier handler
 of: i2c: Export single device registration method
 OF: i2c: Add OF notifier handler
 of: spi: Export single device registration method and accessors
 OF: spi: Add OF notifier handler

Pantelis Antoniou (8):
  OF: Introduce DT overlay support. (v2)
  OF: selftest: Add overlay self-test support. (v2)
  OF: DT-Overlay configfs interface (v2)
  OF: platform: Add OF notifier handler
  of: i2c: Export single device registration method
  OF: i2c: Add OF notifier handler
  of: spi: Export single device registration method and accessors
  OF: spi: Add OF notifier handler

 Documentation/devicetree/bindings/selftest.txt |  14 +
 Documentation/devicetree/overlay-notes.txt     | 137 ++++++
 drivers/base/platform.c                        |  18 +-
 drivers/i2c/i2c-core.c                         | 178 +++++--
 drivers/of/Kconfig                             |  14 +
 drivers/of/Makefile                            |   2 +
 drivers/of/configfs.c                          | 340 +++++++++++++
 drivers/of/overlay.c                           | 656 +++++++++++++++++++++++++
 drivers/of/platform.c                          |  78 +++
 drivers/of/selftest.c                          | 481 ++++++++++++++++++
 drivers/of/testcase-data/testcases.dts         |  16 +
 drivers/of/testcase-data/tests-overlay.dtsi    | 180 +++++++
 drivers/spi/spi.c                              | 334 +++++++++----
 include/linux/i2c.h                            |  10 +
 include/linux/of.h                             |  31 ++
 include/linux/of_platform.h                    |  10 +
 16 files changed, 2351 insertions(+), 148 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/selftest.txt
 create mode 100644 Documentation/devicetree/overlay-notes.txt
 create mode 100644 drivers/of/configfs.c
 create mode 100644 drivers/of/overlay.c
 create mode 100644 drivers/of/testcase-data/tests-overlay.dtsi

-- 
1.7.12

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[PATCH v8 1/8] OF: Introduce DT overlay support. (v2)

[Pantelis Antoniou]

Introduce DT overlay support.

Makes it possible to dynamically overlay a part of the kernel's
tree with another tree that's been dynamically loaded.
Removal of nodes and properties is also possible.

The hard part of applying and reverting the overlay is performed
using changesets.

Documentation about internal and APIs is provided in
	Documentation/devicetree/overlay-notes.txt

Changes since v1:
- Drop delete capability using '-' prefix. The '-' prefixed names
are valid properties and nodes and there is no need for it just yet.
- Do not update special properties - name & phandle ones.
- Change order of node attachment, so that the special property update
works.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
---
 Documentation/devicetree/overlay-notes.txt | 137 ++++++
 drivers/of/Kconfig                         |   7 +
 drivers/of/Makefile                        |   1 +
 drivers/of/overlay.c                       | 656 +++++++++++++++++++++++++++++
 include/linux/of.h                         |  31 ++
 5 files changed, 832 insertions(+)
 create mode 100644 Documentation/devicetree/overlay-notes.txt
 create mode 100644 drivers/of/overlay.c

diff --git a/Documentation/devicetree/overlay-notes.txt b/Documentation/devicetree/overlay-notes.txt
new file mode 100644
index 0000000..b060bd7
--- /dev/null
+++ b/Documentation/devicetree/overlay-notes.txt
@@ -0,0 +1,137 @@
+Device Tree Overlay Notes
+-------------------------
+
+This document describes the implementation of the in-kernel
+device tree overlay functionality residing in drivers/of/overlay.c and is a
+companion document to Documentation/devicetree/dt-object-internal.txt[1] &
+Documentation/devicetree/dynamic-resolution-notes.txt[2]
+
+How overlays work
+-----------------
+
+A Device Tree's overlay purpose is to modify the kernel's live tree, and
+have the modification affecting the state of the the kernel in a way that
+is reflecting the changes.
+Since the kernel mainly deals with devices, any new device node that result
+in an active device should have it created while if the device node is either
+disabled or removed all together, the affected device should be deregistered.
+
+Lets take an example where we have a foo board with the following base tree
+which is taken from [1].
+
+---- foo.dts -----------------------------------------------------------------
+	/* FOO platform */
+	/ {
+		compatible = "corp,foo";
+
+		/* shared resources */
+		res: res {
+		};
+
+		/* On chip peripherals */
+		ocp: ocp {
+			/* peripherals that are always instantiated */
+			peripheral1 { ... };
+		}
+	};
+---- foo.dts -----------------------------------------------------------------
+
+The overlay bar.dts, when loaded (and resolved as described in [2]) should
+
+---- bar.dts -----------------------------------------------------------------
+/plugin/;	/* allow undefined label references and record them */
+/ {
+	....	/* various properties for loader use; i.e. part id etc. */
+	fragment@0 {
+		target = <&ocp>;
+		__overlay__ {
+			/* bar peripheral */
+			bar {
+				compatible = "corp,bar";
+				... /* various properties and child nodes */
+			}
+		};
+	};
+};
+---- bar.dts -----------------------------------------------------------------
+
+result in foo+bar.dts
+
+---- foo+bar.dts -------------------------------------------------------------
+	/* FOO platform + bar peripheral */
+	/ {
+		compatible = "corp,foo";
+
+		/* shared resources */
+		res: res {
+		};
+
+		/* On chip peripherals */
+		ocp: ocp {
+			/* peripherals that are always instantiated */
+			peripheral1 { ... };
+
+			/* bar peripheral */
+			bar {
+				compatible = "corp,bar";
+				... /* various properties and child nodes */
+			}
+		}
+	};
+---- foo+bar.dts -------------------------------------------------------------
+
+As a result of the the overlay, a new device node (bar) has been created
+so a bar platform device will be registered and if a matching device driver
+is loaded the device will be created as expected.
+
+Overlay in-kernel API
+--------------------------------
+
+The API is quite easy to use.
+
+1. Call of_overlay_create() to create and apply an overlay. The return value
+is a cookie identifying this overlay.
+
+2. Call of_overlay_destroy() to remove and cleanup the overlay previously
+created via the call to of_overlay_create(). Removal of an overlay that
+is stacked by another will not be permitted.
+
+Finally, if you need to remove all overlays in one-go, just call
+of_overlay_destroy_all() which will remove every single one in the correct
+order.
+
+Overlay DTS Format
+------------------
+
+The DTS of an overlay should have the following format:
+
+{
+	/* ignored properties by the overlay */
+
+	fragment@0 {	/* first child node */
+
+		target=<phandle>;	/* phandle target of the overlay */
+	or
+		target-path="/path";	/* target path of the overlay */
+
+		__overlay__ {
+			property-a;	/* add property-a to the target */
+			-property-b;	/* remove property-b from target */
+			node-a {	/* add to an existing, or create a node-a */
+				...
+			};
+			-node-b {	/* remove an existing node-b */
+				...
+			};
+		};
+	}
+	fragment@1 {	/* second child node */
+		...
+	};
+	/* more fragments follow */
+}
+
+Using the non-phandle based target method allows one to use a base DT which does
+not contain a __symbols__ node, i.e. it was not compiled with the -@ option.
+The __symbols__ node is only required for the target=<phandle> method, since it
+contains the information required to map from a phandle to a tree location.
diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index 1a13f5b..aa315c4 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -83,4 +83,11 @@ config OF_RESERVED_MEM
 config OF_RESOLVE
 	bool
 
+config OF_OVERLAY
+	bool
+	depends on OF
+	select OF_DYNAMIC
+	select OF_DEVICE
+	select OF_RESOLVE
+
 endmenu # OF
diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index ca9209c..1bfe462 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_OF_PCI_IRQ)  += of_pci_irq.o
 obj-$(CONFIG_OF_MTD)	+= of_mtd.o
 obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
 obj-$(CONFIG_OF_RESOLVE)  += resolver.o
+obj-$(CONFIG_OF_OVERLAY) += overlay.o
 
 CFLAGS_fdt.o = -I$(src)/../../scripts/dtc/libfdt
 CFLAGS_fdt_address.o = -I$(src)/../../scripts/dtc/libfdt
diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
new file mode 100644
index 0000000..ec7675d
--- /dev/null
+++ b/drivers/of/overlay.c
@@ -0,0 +1,656 @@
+/*
+ * Functions for working with device tree overlays
+ *
+ * Copyright (C) 2012 Pantelis Antoniou <panto-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
+ * Copyright (C) 2012 Texas Instruments Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ */
+#undef DEBUG
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+
+#include "of_private.h"
+
+/**
+ * struct of_overlay_info	- Holds a single overlay info
+ * @target:	target of the overlay operation
+ * @overlay:	pointer to the overlay contents node
+ *
+ * Holds a single overlay state, including all the overlay logs &
+ * records.
+ */
+struct of_overlay_info {
+	struct device_node *target;
+	struct device_node *overlay;
+};
+
+/**
+ * struct of_overlay - Holds a complete overlay transaction
+ * @node:	List on which we are located
+ * @count:	Count of ovinfo structures
+ * @ovinfo:	Overlay info array (count size)
+ * @le_list:	List of the overlay logs
+ *
+ * Holds a complete overlay transaction
+ */
+struct of_overlay {
+	int id;
+	struct list_head node;
+	int count;
+	struct of_overlay_info *ovinfo_tab;
+	struct of_changeset cset;
+};
+
+static int of_overlay_apply_one(struct of_overlay *ov,
+		struct device_node *target, const struct device_node *overlay);
+
+static int of_overlay_apply_single_property(struct of_overlay *ov,
+		struct device_node *target, struct property *prop)
+{
+	struct property *propn, *tprop;
+
+	/* NOTE: Multiple changes of single properties not supported */
+	tprop = of_find_property(target, prop->name, NULL);
+
+	/* special properties are not meant to be updated (silent NOP) */
+	if (tprop &&
+		(!of_prop_cmp(prop->name, "name") ||
+		 !of_prop_cmp(prop->name, "phandle") ||
+		 !of_prop_cmp(prop->name, "linux,phandle")))
+		return 0;
+
+	propn = __of_prop_dup(prop, GFP_KERNEL);
+	if (propn == NULL)
+		return -ENOMEM;
+
+	/* not found? add */
+	if (tprop == NULL)
+		return of_changeset_add_property(&ov->cset, target, propn);
+
+	/* found? update */
+	return of_changeset_update_property(&ov->cset, target, propn, tprop);
+}
+
+static int of_overlay_apply_single_device_node(struct of_overlay *ov,
+		struct device_node *target, struct device_node *child)
+{
+	const char *cname;
+	struct device_node *tchild;
+	char *full_name;
+	const char *suffix;
+	int ret;
+
+	/* special case for nodes with a suffix */
+	suffix = strrchr(child->full_name, '@');
+	if (suffix != NULL) {
+		cname = kbasename(child->full_name);
+		if (cname == NULL)
+			return -ENOMEM;
+	} else
+		cname = child->name;
+
+	ret = 0;
+
+	/* NOTE: Multiple mods of created nodes not supported */
+	tchild = of_get_child_by_name(target, cname);
+	if (tchild != NULL) {
+
+		/* apply overlay recursively */
+		ret = of_overlay_apply_one(ov, tchild,
+				child);
+
+		of_node_put(tchild);
+
+	} else {
+		full_name = kasprintf(GFP_KERNEL, "%s/%s",
+				target->full_name, cname);
+		if (full_name == NULL)
+			return -ENOMEM;
+
+		/* create empty tree as a target */
+		tchild = __of_node_alloc(full_name, GFP_KERNEL);
+
+		/* free either way */
+		kfree(full_name);
+
+		if (tchild == NULL)
+			return -ENOMEM;
+
+		/* point to parent */
+		tchild->parent = target;
+
+		/* apply the overlay */
+		ret = of_overlay_apply_one(ov, tchild,
+				child);
+
+		/* attach the node afterwards */
+		if (!ret)
+			ret = of_changeset_attach_node(&ov->cset, tchild);
+
+	}
+
+	return ret;
+}
+
+/*
+ * Apply a single overlay node recursively.
+ *
+ * Note that the in case of an error the target node is left
+ * in a inconsistent state. Error recovery should be performed
+ * by using the tree changes list.
+ */
+static int of_overlay_apply_one(struct of_overlay *ov,
+		struct device_node *target, const struct device_node *overlay)
+{
+	struct device_node *child;
+	struct property *prop;
+	int prev_avail, prop_avail, pass;
+	int ret;
+
+	/*
+	 * Special consideration for status properties
+	 *
+	 * In order to make status property changes work
+	 * we have the following cases:
+	 *
+	 * Enabled device with status change to 'disabled'
+	 *   -> Status property must be first on the record list
+	 *
+	 * Disabled device with status change to 'okay'
+	 *   -> Status property must be last in the record list
+	 *
+	 * That way we don't need a special notifier for
+	 * device status change, a simple notifier on the status
+	 * property is enough.
+	 *
+	 */
+
+	/* note that we require the existence of a status property */
+	prev_avail = of_device_is_available(target) &&
+		of_find_property(target,
+				"compatible", NULL) &&
+		of_find_property(target,
+				"status", NULL);
+
+	/* we make two passes */
+	for (pass = 1; pass <= 2; pass++) {
+
+		for_each_property_of_node(overlay, prop) {
+
+			prop_avail = -1;
+
+			if (of_prop_cmp(prop->name, "status") == 0)
+				prop_avail = strcmp(prop->value, "okay") == 0 ||
+						strcmp(prop->value, "ok") == 0;
+
+			/* skip activation property */
+			if (prev_avail == 0) {
+				/* 0 -> 1, pass #1, skip */
+				if (pass == 1) {
+					if (prop_avail == 1)
+						continue;
+				} else {
+					/* 0 -> 1, pass #2, process */
+					if (prop_avail != 1)
+						continue;
+				}
+			} else {
+				if (pass == 1) {
+					/* 1 -> 0, pass #1, process */
+					if (prop_avail != 0)
+						continue;
+				} else {
+					/* 1 -> 0, pass #2, skip */
+					if (prop_avail == 0)
+						continue;
+				}
+			}
+
+			ret = of_overlay_apply_single_property(ov,
+					target, prop);
+			if (ret != 0) {
+				pr_err("%s: Failed to apply prop @%s/%s\n",
+						__func__, target->full_name,
+						prop->name);
+				return ret;
+			}
+		}
+	}
+
+	for_each_child_of_node(overlay, child) {
+		ret = of_overlay_apply_single_device_node(ov, target, child);
+		if (ret != 0) {
+			pr_err("%s: Failed to apply single node @%s/%s\n",
+					__func__, target->full_name,
+					child->name);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * of_overlay_apply - Apply @count overlays pointed at by @ovinfo_tab
+ * @ov:		Overlay to apply
+ *
+ * Applies the overlays given, while handling all error conditions
+ * appropriately. Either the operation succeeds, or if it fails the
+ * live tree is reverted to the state before the attempt.
+ * Returns 0, or an error if the overlay attempt failed.
+ */
+static int of_overlay_apply(struct of_overlay *ov)
+{
+	struct of_overlay_info *ovinfo;
+	int i, err;
+
+	/* first we apply the overlays atomically */
+	for (i = 0; i < ov->count; i++) {
+
+		ovinfo = &ov->ovinfo_tab[i];
+
+		err = of_overlay_apply_one(ov, ovinfo->target,
+				ovinfo->overlay);
+		if (err != 0) {
+			pr_err("%s: overlay failed '%s'\n",
+				__func__, ovinfo->target->full_name);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Find the target node using a number of different strategies
+ * in order of preference
+ *
+ * "target" property containing the phandle of the target
+ * "target-path" property containing the path of the target
+ *
+ */
+static struct device_node *find_target_node(struct device_node *info_node)
+{
+	const char *path;
+	u32 val;
+	int ret;
+
+	/* first try to go by using the target as a phandle */
+	ret = of_property_read_u32(info_node, "target", &val);
+	if (ret == 0)
+		return of_find_node_by_phandle(val);
+
+	/* now try to locate by path */
+	ret = of_property_read_string(info_node, "target-path", &path);
+	if (ret == 0)
+		return of_find_node_by_path(path);
+
+	pr_err("%s: Failed to find target for node %p (%s)\n", __func__,
+			info_node, info_node->name);
+
+	return NULL;
+}
+
+/**
+ * of_fill_overlay_info	- Fill an overlay info structure
+ * @ov		Overlay to fill
+ * @info_node:	Device node containing the overlay
+ * @ovinfo:	Pointer to the overlay info structure to fill
+ *
+ * Fills an overlay info structure with the overlay information
+ * from a device node. This device node must have a target property
+ * which contains a phandle of the overlay target node, and an
+ * __overlay__ child node which has the overlay contents.
+ * Both ovinfo->target & ovinfo->overlay have their references taken.
+ *
+ * Returns 0 on success, or a negative error value.
+ */
+static int of_fill_overlay_info(struct of_overlay *ov,
+		struct device_node *info_node, struct of_overlay_info *ovinfo)
+{
+	ovinfo->overlay = of_get_child_by_name(info_node, "__overlay__");
+	if (ovinfo->overlay == NULL)
+		goto err_fail;
+
+	ovinfo->target = find_target_node(info_node);
+	if (ovinfo->target == NULL)
+		goto err_fail;
+
+	return 0;
+
+err_fail:
+	of_node_put(ovinfo->target);
+	of_node_put(ovinfo->overlay);
+
+	memset(ovinfo, 0, sizeof(*ovinfo));
+	return -EINVAL;
+}
+
+/**
+ * of_build_overlay_info	- Build an overlay info array
+ * @ov		Overlay to build
+ * @tree:	Device node containing all the overlays
+ *
+ * Helper function that given a tree containing overlay information,
+ * allocates and builds an overlay info array containing it, ready
+ * for use using of_overlay_apply.
+ *
+ * Returns 0 on success with the @cntp @ovinfop pointers valid,
+ * while on error a negative error value is returned.
+ */
+static int of_build_overlay_info(struct of_overlay *ov,
+		struct device_node *tree)
+{
+	struct device_node *node;
+	struct of_overlay_info *ovinfo;
+	int cnt, err;
+
+	/* worst case; every child is a node */
+	cnt = 0;
+	for_each_child_of_node(tree, node)
+		cnt++;
+
+	ovinfo = kcalloc(cnt, sizeof(*ovinfo), GFP_KERNEL);
+	if (ovinfo == NULL)
+		return -ENOMEM;
+
+	cnt = 0;
+	for_each_child_of_node(tree, node) {
+
+		memset(&ovinfo[cnt], 0, sizeof(*ovinfo));
+		err = of_fill_overlay_info(ov, node, &ovinfo[cnt]);
+		if (err == 0)
+			cnt++;
+	}
+
+	/* if nothing filled, return error */
+	if (cnt == 0) {
+		kfree(ovinfo);
+		return -ENODEV;
+	}
+
+	ov->count = cnt;
+	ov->ovinfo_tab = ovinfo;
+
+	return 0;
+}
+
+/**
+ * of_free_overlay_info	- Free an overlay info array
+ * @ov		Overlay to free the overlay info from
+ * @ovinfo_tab:	Array of overlay_info's to free
+ *
+ * Releases the memory of a previously allocated ovinfo array
+ * by of_build_overlay_info.
+ * Returns 0, or an error if the arguments are bogus.
+ */
+static int of_free_overlay_info(struct of_overlay *ov)
+{
+	struct of_overlay_info *ovinfo;
+	int i;
+
+	/* do it in reverse */
+	for (i = ov->count - 1; i >= 0; i--) {
+		ovinfo = &ov->ovinfo_tab[i];
+
+		of_node_put(ovinfo->target);
+		of_node_put(ovinfo->overlay);
+	}
+	kfree(ov->ovinfo_tab);
+
+	return 0;
+}
+
+static LIST_HEAD(ov_list);
+static DEFINE_MUTEX(ov_lock);
+static DEFINE_IDR(ov_idr);
+
+/**
+ * of_overlay_create	- Create and apply an overlay
+ * @tree:	Device node containing all the overlays
+ *
+ * Creates and applies an overlay while also keeping track
+ * of the overlay in a list. This list can be used to prevent
+ * illegal overlay removals.
+ *
+ * Returns the id of the created overlay, or an negative error number
+ */
+int of_overlay_create(struct device_node *tree)
+{
+	struct of_overlay *ov;
+	int err, id;
+
+	/* allocate the overlay structure */
+	ov = kzalloc(sizeof(*ov), GFP_KERNEL);
+	if (ov == NULL)
+		return -ENOMEM;
+	ov->id = -1;
+
+	INIT_LIST_HEAD(&ov->node);
+	mutex_lock(&ov_lock);
+
+	of_changeset_init(&ov->cset);
+
+	id = idr_alloc(&ov_idr, ov, 0, 0, GFP_KERNEL);
+	if (id < 0) {
+		pr_err("%s: idr_alloc() failed for tree@%s\n",
+				__func__, tree->full_name);
+		err = id;
+		goto err_destroy_trans;
+	}
+	ov->id = id;
+
+	/* build the overlay info structures */
+	err = of_build_overlay_info(ov, tree);
+	if (err) {
+		pr_err("%s: of_build_overlay_info() failed for tree@%s\n",
+				__func__, tree->full_name);
+		goto err_free_idr;
+	}
+
+	mutex_lock(&of_mutex);
+
+	/* apply the overlay */
+	err = of_overlay_apply(ov);
+	if (err) {
+		pr_err("%s: of_overlay_apply() failed for tree@%s\n",
+				__func__, tree->full_name);
+		goto err_abort_trans;
+	}
+
+	/* apply the changeset */
+	err = of_changeset_apply(&ov->cset);
+	if (err) {
+		pr_err("%s: of_changeset_apply() failed for tree@%s\n",
+				__func__, tree->full_name);
+		goto err_revert_overlay;
+	}
+
+	mutex_unlock(&of_mutex);
+
+	/* add to the tail of the overlay list */
+	list_add_tail(&ov->node, &ov_list);
+
+	mutex_unlock(&ov_lock);
+
+	return id;
+
+err_revert_overlay:
+err_abort_trans:
+	of_free_overlay_info(ov);
+	mutex_unlock(&of_mutex);
+err_free_idr:
+	idr_remove(&ov_idr, ov->id);
+err_destroy_trans:
+	of_changeset_destroy(&ov->cset);
+	mutex_unlock(&ov_lock);
+	kfree(ov);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(of_overlay_create);
+
+/* check whether the given node, lies under the given tree */
+static int overlay_subtree_check(struct device_node *tree,
+		struct device_node *dn)
+{
+	struct device_node *child;
+
+	/* match? */
+	if (tree == dn)
+		return 1;
+
+	for_each_child_of_node(tree, child) {
+		if (overlay_subtree_check(child, dn))
+			return 1;
+	}
+
+	return 0;
+}
+
+/* check whether this overlay is the topmost */
+static int overlay_is_topmost(struct of_overlay *ov, struct device_node *dn)
+{
+	struct of_overlay *ovt;
+	struct of_changeset_entry *ce;
+
+	list_for_each_entry_reverse(ovt, &ov_list, node) {
+
+		/* if we hit ourselves, we're done */
+		if (ovt == ov)
+			break;
+
+		/* check against each subtree affected by this overlay */
+		list_for_each_entry(ce, &ovt->cset.entries, node) {
+			if (overlay_subtree_check(ce->np, dn)) {
+				pr_err("%s: #%d clashes #%d @%s\n",
+					__func__, ov->id, ovt->id,
+					dn->full_name);
+				return 0;
+			}
+		}
+	}
+
+	/* overlay is topmost */
+	return 1;
+}
+
+/*
+ * We can safely remove the overlay only if it's the top-most one.
+ * Newly applied overlays are inserted at the tail of the overlay list,
+ * so a top most overlay is the one that is closest to the tail.
+ *
+ * The topmost check is done by exploiting this property. For each
+ * affected device node in the log list we check if this overlay is
+ * the one closest to the tail. If another overlay has affected this
+ * device node and is closest to the tail, then removal is not permited.
+ */
+static int overlay_removal_is_ok(struct of_overlay *ov)
+{
+	struct of_changeset_entry *ce;
+
+	list_for_each_entry(ce, &ov->cset.entries, node) {
+		if (!overlay_is_topmost(ov, ce->np)) {
+			pr_err("%s: overlay #%d is not topmost\n",
+					__func__, ov->id);
+			return 0;
+		}
+	}
+
+	return 1;
+}
+
+/**
+ * of_overlay_destroy	- Removes an overlay
+ * @id:	Overlay id number returned by a previous call to of_overlay_create
+ *
+ * Removes an overlay if it is permissible.
+ *
+ * Returns 0 on success, or an negative error number
+ */
+int of_overlay_destroy(int id)
+{
+	struct of_overlay *ov;
+	int err;
+
+	mutex_lock(&ov_lock);
+	ov = idr_find(&ov_idr, id);
+	if (ov == NULL) {
+		err = -ENODEV;
+		pr_err("%s: Could not find overlay #%d\n",
+				__func__, id);
+		goto out;
+	}
+
+	/* check whether the overlay is safe to remove */
+	if (!overlay_removal_is_ok(ov)) {
+		err = -EBUSY;
+		pr_err("%s: removal check failed for overlay #%d\n",
+				__func__, id);
+		goto out;
+	}
+
+
+	list_del(&ov->node);
+
+	mutex_lock(&of_mutex);
+	of_changeset_revert(&ov->cset);
+	mutex_unlock(&of_mutex);
+
+	of_free_overlay_info(ov);
+	idr_remove(&ov_idr, id);
+	of_changeset_destroy(&ov->cset);
+	kfree(ov);
+
+	err = 0;
+
+out:
+	mutex_unlock(&ov_lock);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(of_overlay_destroy);
+
+/**
+ * of_overlay_destroy_all	- Removes all overlays from the system
+ *
+ * Removes all overlays from the system in the correct order.
+ *
+ * Returns 0 on success, or an negative error number
+ */
+int of_overlay_destroy_all(void)
+{
+	struct of_overlay *ov, *ovn;
+
+	mutex_lock(&ov_lock);
+
+	/* the tail of list is guaranteed to be safe to remove */
+	list_for_each_entry_safe_reverse(ov, ovn, &ov_list, node) {
+		list_del(&ov->node);
+
+		mutex_lock(&of_mutex);
+		of_changeset_revert(&ov->cset);
+		mutex_unlock(&of_mutex);
+
+		of_free_overlay_info(ov);
+		idr_remove(&ov_idr, ov->id);
+		kfree(ov);
+	}
+
+
+	mutex_unlock(&ov_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_overlay_destroy_all);
diff --git a/include/linux/of.h b/include/linux/of.h
index 9ff1ec5..9e3e545 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -23,6 +23,7 @@
 #include <linux/spinlock.h>
 #include <linux/topology.h>
 #include <linux/notifier.h>
+#include <linux/list.h>
 
 #include <asm/byteorder.h>
 #include <asm/errno.h>
@@ -873,4 +874,34 @@ static inline int of_changeset_update_property(struct of_changeset *ocs,
 /* CONFIG_OF_RESOLVE api */
 extern int of_resolve_phandles(struct device_node *tree);
 
+/**
+ * Overlay support
+ */
+
+#ifdef CONFIG_OF_OVERLAY
+
+/* ID based overlays; the API for external users */
+int of_overlay_create(struct device_node *tree);
+int of_overlay_destroy(int id);
+int of_overlay_destroy_all(void);
+
+#else
+
+static inline int of_overlay_create(struct device_node *tree)
+{
+	return -ENOTSUPP;
+}
+
+static inline int of_overlay_destroy(int id)
+{
+	return -ENOTSUPP;
+}
+
+static inline int of_overlay_destroy_all(void)
+{
+	return -ENOTSUPP;
+}
+
+#endif
+
 #endif /* _LINUX_OF_H */
-- 
1.7.12

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Re: [PATCH v8 1/8] OF: Introduce DT overlay support. (v2)

[Grant Likely]

On Tue, 28 Oct 2014 22:35:58 +0200
, Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
 wrote:
> Introduce DT overlay support.
> 
> Makes it possible to dynamically overlay a part of the kernel's
> tree with another tree that's been dynamically loaded.
> Removal of nodes and properties is also possible.
> 
> The hard part of applying and reverting the overlay is performed
> using changesets.
> 
> Documentation about internal and APIs is provided in
> 	Documentation/devicetree/overlay-notes.txt

Hi Pantelis,

Comments below. I've picked up this patch, the selftest patch, and the
platform bus patch into my working tree. You can supply me with fixup
patches for the comments below.

Hopefully I'll get my tree published to a test branch tomorrow .

> 
> Changes since v1:
> - Drop delete capability using '-' prefix. The '-' prefixed names
> are valid properties and nodes and there is no need for it just yet.
> - Do not update special properties - name & phandle ones.
> - Change order of node attachment, so that the special property update
> works.
> 
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
> ---
>  Documentation/devicetree/overlay-notes.txt | 137 ++++++
>  drivers/of/Kconfig                         |   7 +
>  drivers/of/Makefile                        |   1 +
>  drivers/of/overlay.c                       | 656 +++++++++++++++++++++++++++++
>  include/linux/of.h                         |  31 ++
>  5 files changed, 832 insertions(+)
>  create mode 100644 Documentation/devicetree/overlay-notes.txt
>  create mode 100644 drivers/of/overlay.c
> 
> diff --git a/Documentation/devicetree/overlay-notes.txt b/Documentation/devicetree/overlay-notes.txt
> new file mode 100644
> index 0000000..b060bd7
> --- /dev/null
> +++ b/Documentation/devicetree/overlay-notes.txt
> @@ -0,0 +1,137 @@
> +Device Tree Overlay Notes
> +-------------------------
> +
> +This document describes the implementation of the in-kernel
> +device tree overlay functionality residing in drivers/of/overlay.c and is a
> +companion document to Documentation/devicetree/dt-object-internal.txt[1] &
> +Documentation/devicetree/dynamic-resolution-notes.txt[2]
> +
> +How overlays work
> +-----------------
> +
> +A Device Tree's overlay purpose is to modify the kernel's live tree, and
> +have the modification affecting the state of the the kernel in a way that
> +is reflecting the changes.
> +Since the kernel mainly deals with devices, any new device node that result
> +in an active device should have it created while if the device node is either
> +disabled or removed all together, the affected device should be deregistered.
> +
> +Lets take an example where we have a foo board with the following base tree
> +which is taken from [1].
> +
> +---- foo.dts -----------------------------------------------------------------
> +	/* FOO platform */
> +	/ {
> +		compatible = "corp,foo";
> +
> +		/* shared resources */
> +		res: res {
> +		};
> +
> +		/* On chip peripherals */
> +		ocp: ocp {
> +			/* peripherals that are always instantiated */
> +			peripheral1 { ... };
> +		}
> +	};
> +---- foo.dts -----------------------------------------------------------------
> +
> +The overlay bar.dts, when loaded (and resolved as described in [2]) should
> +
> +---- bar.dts -----------------------------------------------------------------
> +/plugin/;	/* allow undefined label references and record them */
> +/ {
> +	....	/* various properties for loader use; i.e. part id etc. */
> +	fragment@0 {
> +		target = <&ocp>;
> +		__overlay__ {
> +			/* bar peripheral */
> +			bar {
> +				compatible = "corp,bar";
> +				... /* various properties and child nodes */
> +			}
> +		};
> +	};
> +};
> +---- bar.dts -----------------------------------------------------------------
> +
> +result in foo+bar.dts
> +
> +---- foo+bar.dts -------------------------------------------------------------
> +	/* FOO platform + bar peripheral */
> +	/ {
> +		compatible = "corp,foo";
> +
> +		/* shared resources */
> +		res: res {
> +		};
> +
> +		/* On chip peripherals */
> +		ocp: ocp {
> +			/* peripherals that are always instantiated */
> +			peripheral1 { ... };
> +
> +			/* bar peripheral */
> +			bar {
> +				compatible = "corp,bar";
> +				... /* various properties and child nodes */
> +			}
> +		}
> +	};
> +---- foo+bar.dts -------------------------------------------------------------
> +
> +As a result of the the overlay, a new device node (bar) has been created
> +so a bar platform device will be registered and if a matching device driver
> +is loaded the device will be created as expected.
> +
> +Overlay in-kernel API
> +--------------------------------
> +
> +The API is quite easy to use.
> +
> +1. Call of_overlay_create() to create and apply an overlay. The return value
> +is a cookie identifying this overlay.
> +
> +2. Call of_overlay_destroy() to remove and cleanup the overlay previously
> +created via the call to of_overlay_create(). Removal of an overlay that
> +is stacked by another will not be permitted.
> +
> +Finally, if you need to remove all overlays in one-go, just call
> +of_overlay_destroy_all() which will remove every single one in the correct
> +order.
> +
> +Overlay DTS Format
> +------------------
> +
> +The DTS of an overlay should have the following format:
> +
> +{
> +	/* ignored properties by the overlay */
> +
> +	fragment@0 {	/* first child node */
> +
> +		target=<phandle>;	/* phandle target of the overlay */
> +	or
> +		target-path="/path";	/* target path of the overlay */
> +
> +		__overlay__ {
> +			property-a;	/* add property-a to the target */
> +			-property-b;	/* remove property-b from target */
> +			node-a {	/* add to an existing, or create a node-a */
> +				...
> +			};
> +			-node-b {	/* remove an existing node-b */
> +				...
> +			};

-property-b and -node-b need to be removed from the example.

> +		};
> +	}
> +	fragment@1 {	/* second child node */
> +		...
> +	};
> +	/* more fragments follow */
> +}
> +
> +Using the non-phandle based target method allows one to use a base DT which does
> +not contain a __symbols__ node, i.e. it was not compiled with the -@ option.
> +The __symbols__ node is only required for the target=<phandle> method, since it
> +contains the information required to map from a phandle to a tree location.
> diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
> index 1a13f5b..aa315c4 100644
> --- a/drivers/of/Kconfig
> +++ b/drivers/of/Kconfig
> @@ -83,4 +83,11 @@ config OF_RESERVED_MEM
>  config OF_RESOLVE
>  	bool
>  
> +config OF_OVERLAY
> +	bool
> +	depends on OF
> +	select OF_DYNAMIC
> +	select OF_DEVICE
> +	select OF_RESOLVE
> +
>  endmenu # OF
> diff --git a/drivers/of/Makefile b/drivers/of/Makefile
> index ca9209c..1bfe462 100644
> --- a/drivers/of/Makefile
> +++ b/drivers/of/Makefile
> @@ -14,6 +14,7 @@ obj-$(CONFIG_OF_PCI_IRQ)  += of_pci_irq.o
>  obj-$(CONFIG_OF_MTD)	+= of_mtd.o
>  obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
>  obj-$(CONFIG_OF_RESOLVE)  += resolver.o
> +obj-$(CONFIG_OF_OVERLAY) += overlay.o
>  
>  CFLAGS_fdt.o = -I$(src)/../../scripts/dtc/libfdt
>  CFLAGS_fdt_address.o = -I$(src)/../../scripts/dtc/libfdt
> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> new file mode 100644
> index 0000000..ec7675d
> --- /dev/null
> +++ b/drivers/of/overlay.c
> @@ -0,0 +1,656 @@
> +/*
> + * Functions for working with device tree overlays
> + *
> + * Copyright (C) 2012 Pantelis Antoniou <panto-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
> + * Copyright (C) 2012 Texas Instruments Inc.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * version 2 as published by the Free Software Foundation.
> + */
> +#undef DEBUG
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/string.h>
> +#include <linux/ctype.h>
> +#include <linux/errno.h>
> +#include <linux/string.h>
> +#include <linux/slab.h>
> +#include <linux/err.h>
> +
> +#include "of_private.h"
> +
> +/**
> + * struct of_overlay_info	- Holds a single overlay info
> + * @target:	target of the overlay operation
> + * @overlay:	pointer to the overlay contents node
> + *
> + * Holds a single overlay state, including all the overlay logs &
> + * records.
> + */
> +struct of_overlay_info {
> +	struct device_node *target;
> +	struct device_node *overlay;
> +};
> +
> +/**
> + * struct of_overlay - Holds a complete overlay transaction
> + * @node:	List on which we are located
> + * @count:	Count of ovinfo structures
> + * @ovinfo:	Overlay info array (count size)
> + * @le_list:	List of the overlay logs

The documentation is out-of-date. Please supply a fixup patch.

> + *
> + * Holds a complete overlay transaction
> + */
> +struct of_overlay {
> +	int id;
> +	struct list_head node;
> +	int count;
> +	struct of_overlay_info *ovinfo_tab;
> +	struct of_changeset cset;
> +};
> +
> +static int of_overlay_apply_one(struct of_overlay *ov,
> +		struct device_node *target, const struct device_node *overlay);
> +
> +static int of_overlay_apply_single_property(struct of_overlay *ov,
> +		struct device_node *target, struct property *prop)
> +{
> +	struct property *propn, *tprop;
> +
> +	/* NOTE: Multiple changes of single properties not supported */
> +	tprop = of_find_property(target, prop->name, NULL);
> +
> +	/* special properties are not meant to be updated (silent NOP) */
> +	if (tprop &&
> +		(!of_prop_cmp(prop->name, "name") ||
> +		 !of_prop_cmp(prop->name, "phandle") ||
> +		 !of_prop_cmp(prop->name, "linux,phandle")))
> +		return 0;

What is the reason for these tests being conditional on the presence of
the property in the node?

> +
> +	propn = __of_prop_dup(prop, GFP_KERNEL);
> +	if (propn == NULL)
> +		return -ENOMEM;
> +
> +	/* not found? add */
> +	if (tprop == NULL)
> +		return of_changeset_add_property(&ov->cset, target, propn);
> +
> +	/* found? update */
> +	return of_changeset_update_property(&ov->cset, target, propn, tprop);
> +}
> +
> +static int of_overlay_apply_single_device_node(struct of_overlay *ov,
> +		struct device_node *target, struct device_node *child)
> +{
> +	const char *cname;
> +	struct device_node *tchild;
> +	char *full_name;
> +	const char *suffix;
> +	int ret;
> +
> +	/* special case for nodes with a suffix */
> +	suffix = strrchr(child->full_name, '@');
> +	if (suffix != NULL) {
> +		cname = kbasename(child->full_name);
> +		if (cname == NULL)
> +			return -ENOMEM;
> +	} else
> +		cname = child->name;

So, if it has a unit address suffix, kbasename is used. If it doesn't
have a suffix, child->name is used because it is cheaper that using
kbasename? If that's the reason, I don't think the code complexity is
worth it since the cost should be negligable. Can kbasename() be used
always?

> +
> +	ret = 0;
> +
> +	/* NOTE: Multiple mods of created nodes not supported */
> +	tchild = of_get_child_by_name(target, cname);
> +	if (tchild != NULL) {
> +
> +		/* apply overlay recursively */
> +		ret = of_overlay_apply_one(ov, tchild,
> +				child);
> +
> +		of_node_put(tchild);
> +
> +	} else {
> +		full_name = kasprintf(GFP_KERNEL, "%s/%s",
> +				target->full_name, cname);
> +		if (full_name == NULL)
> +			return -ENOMEM;
> +
> +		/* create empty tree as a target */
> +		tchild = __of_node_alloc(full_name, GFP_KERNEL);
> +
> +		/* free either way */
> +		kfree(full_name);
> +
> +		if (tchild == NULL)
> +			return -ENOMEM;
> +
> +		/* point to parent */
> +		tchild->parent = target;

As discussed on IRC, if a node doesn't already exist in the tree, then
the properties can be duplicated with the node. There is no need to do a
of_changeset_add_property() on each and every node. That just makes the
load on notifiers a lot heavier and adds more processing on add and
remove.

> +
> +		/* apply the overlay */
> +		ret = of_overlay_apply_one(ov, tchild,
> +				child);
> +
> +		/* attach the node afterwards */
> +		if (!ret)
> +			ret = of_changeset_attach_node(&ov->cset, tchild);

It looks to me like the parent is getting added /after/ the child is
added in the changeset stack. That doesn't look right to me. Wouldn't
that also mean that the child node get registered on sysfs after the
parent nodes?

> +
> +	}
> +
> +	return ret;
> +}
> +
> +/*
> + * Apply a single overlay node recursively.
> + *
> + * Note that the in case of an error the target node is left
> + * in a inconsistent state. Error recovery should be performed
> + * by using the tree changes list.
> + */
> +static int of_overlay_apply_one(struct of_overlay *ov,
> +		struct device_node *target, const struct device_node *overlay)
> +{
> +	struct device_node *child;
> +	struct property *prop;
> +	int prev_avail, prop_avail, pass;
> +	int ret;
> +
> +	/*
> +	 * Special consideration for status properties
> +	 *
> +	 * In order to make status property changes work
> +	 * we have the following cases:
> +	 *
> +	 * Enabled device with status change to 'disabled'
> +	 *   -> Status property must be first on the record list
> +	 *
> +	 * Disabled device with status change to 'okay'
> +	 *   -> Status property must be last in the record list
> +	 *
> +	 * That way we don't need a special notifier for
> +	 * device status change, a simple notifier on the status
> +	 * property is enough.
> +	 *
> +	 */

Is this true anymore? The notifiers are held back until all the changes
are made to the tree, so regardless of what order the notifiers are
emitted in, the tree will always be in the correct state.

> +
> +	/* note that we require the existence of a status property */
> +	prev_avail = of_device_is_available(target) &&
> +		of_find_property(target,
> +				"compatible", NULL) &&
> +		of_find_property(target,
> +				"status", NULL);
> +
> +	/* we make two passes */
> +	for (pass = 1; pass <= 2; pass++) {
> +
> +		for_each_property_of_node(overlay, prop) {
> +
> +			prop_avail = -1;
> +
> +			if (of_prop_cmp(prop->name, "status") == 0)
> +				prop_avail = strcmp(prop->value, "okay") == 0 ||
> +						strcmp(prop->value, "ok") == 0;
> +
> +			/* skip activation property */
> +			if (prev_avail == 0) {
> +				/* 0 -> 1, pass #1, skip */
> +				if (pass == 1) {
> +					if (prop_avail == 1)
> +						continue;
> +				} else {
> +					/* 0 -> 1, pass #2, process */
> +					if (prop_avail != 1)
> +						continue;
> +				}
> +			} else {
> +				if (pass == 1) {
> +					/* 1 -> 0, pass #1, process */
> +					if (prop_avail != 0)
> +						continue;
> +				} else {
> +					/* 1 -> 0, pass #2, skip */
> +					if (prop_avail == 0)
> +						continue;
> +				}
> +			}
> +
> +			ret = of_overlay_apply_single_property(ov,
> +					target, prop);
> +			if (ret != 0) {
> +				pr_err("%s: Failed to apply prop @%s/%s\n",
> +						__func__, target->full_name,
> +						prop->name);
> +				return ret;
> +			}
> +		}
> +	}
> +
> +	for_each_child_of_node(overlay, child) {
> +		ret = of_overlay_apply_single_device_node(ov, target, child);
> +		if (ret != 0) {
> +			pr_err("%s: Failed to apply single node @%s/%s\n",
> +					__func__, target->full_name,
> +					child->name);
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * of_overlay_apply - Apply @count overlays pointed at by @ovinfo_tab
> + * @ov:		Overlay to apply
> + *
> + * Applies the overlays given, while handling all error conditions
> + * appropriately. Either the operation succeeds, or if it fails the
> + * live tree is reverted to the state before the attempt.
> + * Returns 0, or an error if the overlay attempt failed.
> + */
> +static int of_overlay_apply(struct of_overlay *ov)
> +{
> +	struct of_overlay_info *ovinfo;
> +	int i, err;
> +
> +	/* first we apply the overlays atomically */
> +	for (i = 0; i < ov->count; i++) {
> +
> +		ovinfo = &ov->ovinfo_tab[i];
> +
> +		err = of_overlay_apply_one(ov, ovinfo->target,
> +				ovinfo->overlay);
> +		if (err != 0) {
> +			pr_err("%s: overlay failed '%s'\n",
> +				__func__, ovinfo->target->full_name);
> +			return err;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * Find the target node using a number of different strategies
> + * in order of preference
> + *
> + * "target" property containing the phandle of the target
> + * "target-path" property containing the path of the target
> + *
> + */
> +static struct device_node *find_target_node(struct device_node *info_node)
> +{
> +	const char *path;
> +	u32 val;
> +	int ret;
> +
> +	/* first try to go by using the target as a phandle */
> +	ret = of_property_read_u32(info_node, "target", &val);
> +	if (ret == 0)
> +		return of_find_node_by_phandle(val);
> +
> +	/* now try to locate by path */
> +	ret = of_property_read_string(info_node, "target-path", &path);
> +	if (ret == 0)
> +		return of_find_node_by_path(path);
> +
> +	pr_err("%s: Failed to find target for node %p (%s)\n", __func__,
> +			info_node, info_node->name);
> +
> +	return NULL;
> +}
> +
> +/**
> + * of_fill_overlay_info	- Fill an overlay info structure
> + * @ov		Overlay to fill
> + * @info_node:	Device node containing the overlay
> + * @ovinfo:	Pointer to the overlay info structure to fill
> + *
> + * Fills an overlay info structure with the overlay information
> + * from a device node. This device node must have a target property
> + * which contains a phandle of the overlay target node, and an
> + * __overlay__ child node which has the overlay contents.
> + * Both ovinfo->target & ovinfo->overlay have their references taken.
> + *
> + * Returns 0 on success, or a negative error value.
> + */
> +static int of_fill_overlay_info(struct of_overlay *ov,
> +		struct device_node *info_node, struct of_overlay_info *ovinfo)
> +{
> +	ovinfo->overlay = of_get_child_by_name(info_node, "__overlay__");
> +	if (ovinfo->overlay == NULL)
> +		goto err_fail;
> +
> +	ovinfo->target = find_target_node(info_node);
> +	if (ovinfo->target == NULL)
> +		goto err_fail;
> +
> +	return 0;
> +
> +err_fail:
> +	of_node_put(ovinfo->target);
> +	of_node_put(ovinfo->overlay);
> +
> +	memset(ovinfo, 0, sizeof(*ovinfo));
> +	return -EINVAL;
> +}
> +
> +/**
> + * of_build_overlay_info	- Build an overlay info array
> + * @ov		Overlay to build
> + * @tree:	Device node containing all the overlays
> + *
> + * Helper function that given a tree containing overlay information,
> + * allocates and builds an overlay info array containing it, ready
> + * for use using of_overlay_apply.
> + *
> + * Returns 0 on success with the @cntp @ovinfop pointers valid,
> + * while on error a negative error value is returned.
> + */
> +static int of_build_overlay_info(struct of_overlay *ov,
> +		struct device_node *tree)
> +{
> +	struct device_node *node;
> +	struct of_overlay_info *ovinfo;
> +	int cnt, err;
> +
> +	/* worst case; every child is a node */
> +	cnt = 0;
> +	for_each_child_of_node(tree, node)
> +		cnt++;
> +
> +	ovinfo = kcalloc(cnt, sizeof(*ovinfo), GFP_KERNEL);
> +	if (ovinfo == NULL)
> +		return -ENOMEM;
> +
> +	cnt = 0;
> +	for_each_child_of_node(tree, node) {
> +
> +		memset(&ovinfo[cnt], 0, sizeof(*ovinfo));
> +		err = of_fill_overlay_info(ov, node, &ovinfo[cnt]);
> +		if (err == 0)
> +			cnt++;
> +	}
> +
> +	/* if nothing filled, return error */
> +	if (cnt == 0) {
> +		kfree(ovinfo);
> +		return -ENODEV;
> +	}
> +
> +	ov->count = cnt;
> +	ov->ovinfo_tab = ovinfo;
> +
> +	return 0;
> +}
> +
> +/**
> + * of_free_overlay_info	- Free an overlay info array
> + * @ov		Overlay to free the overlay info from
> + * @ovinfo_tab:	Array of overlay_info's to free
> + *
> + * Releases the memory of a previously allocated ovinfo array
> + * by of_build_overlay_info.
> + * Returns 0, or an error if the arguments are bogus.
> + */
> +static int of_free_overlay_info(struct of_overlay *ov)
> +{
> +	struct of_overlay_info *ovinfo;
> +	int i;
> +
> +	/* do it in reverse */
> +	for (i = ov->count - 1; i >= 0; i--) {
> +		ovinfo = &ov->ovinfo_tab[i];
> +
> +		of_node_put(ovinfo->target);
> +		of_node_put(ovinfo->overlay);
> +	}
> +	kfree(ov->ovinfo_tab);
> +
> +	return 0;
> +}
> +
> +static LIST_HEAD(ov_list);
> +static DEFINE_MUTEX(ov_lock);
> +static DEFINE_IDR(ov_idr);
> +
> +/**
> + * of_overlay_create	- Create and apply an overlay
> + * @tree:	Device node containing all the overlays
> + *
> + * Creates and applies an overlay while also keeping track
> + * of the overlay in a list. This list can be used to prevent
> + * illegal overlay removals.
> + *
> + * Returns the id of the created overlay, or an negative error number
> + */
> +int of_overlay_create(struct device_node *tree)
> +{
> +	struct of_overlay *ov;
> +	int err, id;
> +
> +	/* allocate the overlay structure */
> +	ov = kzalloc(sizeof(*ov), GFP_KERNEL);
> +	if (ov == NULL)
> +		return -ENOMEM;
> +	ov->id = -1;
> +
> +	INIT_LIST_HEAD(&ov->node);
> +	mutex_lock(&ov_lock);

Holding the of_mutex lock over the entire operation is probably
sufficent. I don't think the locking needs the complexity of multiple
mutexes.

> +
> +	of_changeset_init(&ov->cset);
> +
> +	id = idr_alloc(&ov_idr, ov, 0, 0, GFP_KERNEL);
> +	if (id < 0) {
> +		pr_err("%s: idr_alloc() failed for tree@%s\n",
> +				__func__, tree->full_name);
> +		err = id;
> +		goto err_destroy_trans;
> +	}
> +	ov->id = id;
> +
> +	/* build the overlay info structures */
> +	err = of_build_overlay_info(ov, tree);
> +	if (err) {
> +		pr_err("%s: of_build_overlay_info() failed for tree@%s\n",
> +				__func__, tree->full_name);
> +		goto err_free_idr;
> +	}
> +
> +	mutex_lock(&of_mutex);
> +
> +	/* apply the overlay */
> +	err = of_overlay_apply(ov);
> +	if (err) {
> +		pr_err("%s: of_overlay_apply() failed for tree@%s\n",
> +				__func__, tree->full_name);
> +		goto err_abort_trans;
> +	}
> +
> +	/* apply the changeset */
> +	err = of_changeset_apply(&ov->cset);
> +	if (err) {
> +		pr_err("%s: of_changeset_apply() failed for tree@%s\n",
> +				__func__, tree->full_name);
> +		goto err_revert_overlay;
> +	}
> +
> +	mutex_unlock(&of_mutex);
> +
> +	/* add to the tail of the overlay list */
> +	list_add_tail(&ov->node, &ov_list);
> +
> +	mutex_unlock(&ov_lock);
> +
> +	return id;
> +
> +err_revert_overlay:
> +err_abort_trans:
> +	of_free_overlay_info(ov);
> +	mutex_unlock(&of_mutex);
> +err_free_idr:
> +	idr_remove(&ov_idr, ov->id);
> +err_destroy_trans:
> +	of_changeset_destroy(&ov->cset);
> +	mutex_unlock(&ov_lock);
> +	kfree(ov);
> +
> +	return err;
> +}
> +EXPORT_SYMBOL_GPL(of_overlay_create);
> +
> +/* check whether the given node, lies under the given tree */
> +static int overlay_subtree_check(struct device_node *tree,
> +		struct device_node *dn)
> +{
> +	struct device_node *child;
> +
> +	/* match? */
> +	if (tree == dn)
> +		return 1;
> +
> +	for_each_child_of_node(tree, child) {
> +		if (overlay_subtree_check(child, dn))
> +			return 1;
> +	}
> +
> +	return 0;
> +}
> +
> +/* check whether this overlay is the topmost */
> +static int overlay_is_topmost(struct of_overlay *ov, struct device_node *dn)
> +{
> +	struct of_overlay *ovt;
> +	struct of_changeset_entry *ce;
> +
> +	list_for_each_entry_reverse(ovt, &ov_list, node) {
> +
> +		/* if we hit ourselves, we're done */
> +		if (ovt == ov)
> +			break;
> +
> +		/* check against each subtree affected by this overlay */
> +		list_for_each_entry(ce, &ovt->cset.entries, node) {
> +			if (overlay_subtree_check(ce->np, dn)) {
> +				pr_err("%s: #%d clashes #%d @%s\n",
> +					__func__, ov->id, ovt->id,
> +					dn->full_name);
> +				return 0;
> +			}
> +		}
> +	}
> +
> +	/* overlay is topmost */
> +	return 1;
> +}
> +
> +/*
> + * We can safely remove the overlay only if it's the top-most one.
> + * Newly applied overlays are inserted at the tail of the overlay list,
> + * so a top most overlay is the one that is closest to the tail.
> + *
> + * The topmost check is done by exploiting this property. For each
> + * affected device node in the log list we check if this overlay is
> + * the one closest to the tail. If another overlay has affected this
> + * device node and is closest to the tail, then removal is not permited.
> + */
> +static int overlay_removal_is_ok(struct of_overlay *ov)
> +{
> +	struct of_changeset_entry *ce;
> +
> +	list_for_each_entry(ce, &ov->cset.entries, node) {
> +		if (!overlay_is_topmost(ov, ce->np)) {
> +			pr_err("%s: overlay #%d is not topmost\n",
> +					__func__, ov->id);
> +			return 0;
> +		}
> +	}
> +
> +	return 1;
> +}
> +
> +/**
> + * of_overlay_destroy	- Removes an overlay
> + * @id:	Overlay id number returned by a previous call to of_overlay_create
> + *
> + * Removes an overlay if it is permissible.
> + *
> + * Returns 0 on success, or an negative error number
> + */
> +int of_overlay_destroy(int id)
> +{
> +	struct of_overlay *ov;
> +	int err;
> +
> +	mutex_lock(&ov_lock);
> +	ov = idr_find(&ov_idr, id);
> +	if (ov == NULL) {
> +		err = -ENODEV;
> +		pr_err("%s: Could not find overlay #%d\n",
> +				__func__, id);
> +		goto out;
> +	}
> +
> +	/* check whether the overlay is safe to remove */
> +	if (!overlay_removal_is_ok(ov)) {
> +		err = -EBUSY;
> +		pr_err("%s: removal check failed for overlay #%d\n",
> +				__func__, id);
> +		goto out;
> +	}
> +
> +
> +	list_del(&ov->node);
> +
> +	mutex_lock(&of_mutex);
> +	of_changeset_revert(&ov->cset);
> +	mutex_unlock(&of_mutex);
> +
> +	of_free_overlay_info(ov);
> +	idr_remove(&ov_idr, id);
> +	of_changeset_destroy(&ov->cset);
> +	kfree(ov);
> +
> +	err = 0;
> +
> +out:
> +	mutex_unlock(&ov_lock);
> +
> +	return err;
> +}
> +EXPORT_SYMBOL_GPL(of_overlay_destroy);
> +
> +/**
> + * of_overlay_destroy_all	- Removes all overlays from the system
> + *
> + * Removes all overlays from the system in the correct order.
> + *
> + * Returns 0 on success, or an negative error number
> + */
> +int of_overlay_destroy_all(void)
> +{
> +	struct of_overlay *ov, *ovn;
> +
> +	mutex_lock(&ov_lock);
> +
> +	/* the tail of list is guaranteed to be safe to remove */
> +	list_for_each_entry_safe_reverse(ov, ovn, &ov_list, node) {
> +		list_del(&ov->node);
> +
> +		mutex_lock(&of_mutex);
> +		of_changeset_revert(&ov->cset);
> +		mutex_unlock(&of_mutex);
> +
> +		of_free_overlay_info(ov);
> +		idr_remove(&ov_idr, ov->id);
> +		kfree(ov);
> +	}
> +
> +
> +	mutex_unlock(&ov_lock);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(of_overlay_destroy_all);
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 9ff1ec5..9e3e545 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -23,6 +23,7 @@
>  #include <linux/spinlock.h>
>  #include <linux/topology.h>
>  #include <linux/notifier.h>
> +#include <linux/list.h>
>  
>  #include <asm/byteorder.h>
>  #include <asm/errno.h>
> @@ -873,4 +874,34 @@ static inline int of_changeset_update_property(struct of_changeset *ocs,
>  /* CONFIG_OF_RESOLVE api */
>  extern int of_resolve_phandles(struct device_node *tree);
>  
> +/**
> + * Overlay support
> + */
> +
> +#ifdef CONFIG_OF_OVERLAY
> +
> +/* ID based overlays; the API for external users */
> +int of_overlay_create(struct device_node *tree);
> +int of_overlay_destroy(int id);
> +int of_overlay_destroy_all(void);
> +
> +#else
> +
> +static inline int of_overlay_create(struct device_node *tree)
> +{
> +	return -ENOTSUPP;
> +}
> +
> +static inline int of_overlay_destroy(int id)
> +{
> +	return -ENOTSUPP;
> +}
> +
> +static inline int of_overlay_destroy_all(void)
> +{
> +	return -ENOTSUPP;
> +}
> +
> +#endif
> +
>  #endif /* _LINUX_OF_H */
> -- 
> 1.7.12
> 

Re: [PATCH v8 1/8] OF: Introduce DT overlay support. (v2)

[Pantelis Antoniou]

Hi Grant,

> On Nov 14, 2014, at 01:36 , Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> wrote:
> 
> On Tue, 28 Oct 2014 22:35:58 +0200
> , Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
> wrote:
>> Introduce DT overlay support.
>> 
>> Makes it possible to dynamically overlay a part of the kernel's
>> tree with another tree that's been dynamically loaded.
>> Removal of nodes and properties is also possible.
>> 
>> The hard part of applying and reverting the overlay is performed
>> using changesets.
>> 
>> Documentation about internal and APIs is provided in
>> 	Documentation/devicetree/overlay-notes.txt
> 
> Hi Pantelis,
> 
> Comments below. I've picked up this patch, the selftest patch, and the
> platform bus patch into my working tree. You can supply me with fixup
> patches for the comments below.
> 
> Hopefully I'll get my tree published to a test branch tomorrow .
> 
>> 
>> Changes since v1:
>> - Drop delete capability using '-' prefix. The '-' prefixed names
>> are valid properties and nodes and there is no need for it just yet.
>> - Do not update special properties - name & phandle ones.
>> - Change order of node attachment, so that the special property update
>> works.
>> 
>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
>> ---
>> Documentation/devicetree/overlay-notes.txt | 137 ++++++
>> drivers/of/Kconfig                         |   7 +
>> drivers/of/Makefile                        |   1 +
>> drivers/of/overlay.c                       | 656 +++++++++++++++++++++++++++++
>> include/linux/of.h                         |  31 ++
>> 5 files changed, 832 insertions(+)
>> create mode 100644 Documentation/devicetree/overlay-notes.txt
>> create mode 100644 drivers/of/overlay.c
>> 
>> diff --git a/Documentation/devicetree/overlay-notes.txt b/Documentation/devicetree/overlay-notes.txt
>> new file mode 100644
>> index 0000000..b060bd7
>> --- /dev/null
>> +++ b/Documentation/devicetree/overlay-notes.txt
>> @@ -0,0 +1,137 @@
>> +Device Tree Overlay Notes
>> +-------------------------
>> +
>> +This document describes the implementation of the in-kernel
>> +device tree overlay functionality residing in drivers/of/overlay.c and is a
>> +companion document to Documentation/devicetree/dt-object-internal.txt[1] &
>> +Documentation/devicetree/dynamic-resolution-notes.txt[2]
>> +
>> +How overlays work
>> +-----------------
>> +
>> +A Device Tree's overlay purpose is to modify the kernel's live tree, and
>> +have the modification affecting the state of the the kernel in a way that
>> +is reflecting the changes.
>> +Since the kernel mainly deals with devices, any new device node that result
>> +in an active device should have it created while if the device node is either
>> +disabled or removed all together, the affected device should be deregistered.
>> +
>> +Lets take an example where we have a foo board with the following base tree
>> +which is taken from [1].
>> +
>> +---- foo.dts -----------------------------------------------------------------
>> +	/* FOO platform */
>> +	/ {
>> +		compatible = "corp,foo";
>> +
>> +		/* shared resources */
>> +		res: res {
>> +		};
>> +
>> +		/* On chip peripherals */
>> +		ocp: ocp {
>> +			/* peripherals that are always instantiated */
>> +			peripheral1 { ... };
>> +		}
>> +	};
>> +---- foo.dts -----------------------------------------------------------------
>> +
>> +The overlay bar.dts, when loaded (and resolved as described in [2]) should
>> +
>> +---- bar.dts -----------------------------------------------------------------
>> +/plugin/;	/* allow undefined label references and record them */
>> +/ {
>> +	....	/* various properties for loader use; i.e. part id etc. */
>> +	fragment@0 {
>> +		target = <&ocp>;
>> +		__overlay__ {
>> +			/* bar peripheral */
>> +			bar {
>> +				compatible = "corp,bar";
>> +				... /* various properties and child nodes */
>> +			}
>> +		};
>> +	};
>> +};
>> +---- bar.dts -----------------------------------------------------------------
>> +
>> +result in foo+bar.dts
>> +
>> +---- foo+bar.dts -------------------------------------------------------------
>> +	/* FOO platform + bar peripheral */
>> +	/ {
>> +		compatible = "corp,foo";
>> +
>> +		/* shared resources */
>> +		res: res {
>> +		};
>> +
>> +		/* On chip peripherals */
>> +		ocp: ocp {
>> +			/* peripherals that are always instantiated */
>> +			peripheral1 { ... };
>> +
>> +			/* bar peripheral */
>> +			bar {
>> +				compatible = "corp,bar";
>> +				... /* various properties and child nodes */
>> +			}
>> +		}
>> +	};
>> +---- foo+bar.dts -------------------------------------------------------------
>> +
>> +As a result of the the overlay, a new device node (bar) has been created
>> +so a bar platform device will be registered and if a matching device driver
>> +is loaded the device will be created as expected.
>> +
>> +Overlay in-kernel API
>> +--------------------------------
>> +
>> +The API is quite easy to use.
>> +
>> +1. Call of_overlay_create() to create and apply an overlay. The return value
>> +is a cookie identifying this overlay.
>> +
>> +2. Call of_overlay_destroy() to remove and cleanup the overlay previously
>> +created via the call to of_overlay_create(). Removal of an overlay that
>> +is stacked by another will not be permitted.
>> +
>> +Finally, if you need to remove all overlays in one-go, just call
>> +of_overlay_destroy_all() which will remove every single one in the correct
>> +order.
>> +
>> +Overlay DTS Format
>> +------------------
>> +
>> +The DTS of an overlay should have the following format:
>> +
>> +{
>> +	/* ignored properties by the overlay */
>> +
>> +	fragment@0 {	/* first child node */
>> +
>> +		target=<phandle>;	/* phandle target of the overlay */
>> +	or
>> +		target-path="/path";	/* target path of the overlay */
>> +
>> +		__overlay__ {
>> +			property-a;	/* add property-a to the target */
>> +			-property-b;	/* remove property-b from target */
>> +			node-a {	/* add to an existing, or create a node-a */
>> +				...
>> +			};
>> +			-node-b {	/* remove an existing node-b */
>> +				...
>> +			};
> 
> -property-b and -node-b need to be removed from the example.
> 

OK

>> +		};
>> +	}
>> +	fragment@1 {	/* second child node */
>> +		...
>> +	};
>> +	/* more fragments follow */
>> +}
>> +
>> +Using the non-phandle based target method allows one to use a base DT which does
>> +not contain a __symbols__ node, i.e. it was not compiled with the -@ option.
>> +The __symbols__ node is only required for the target=<phandle> method, since it
>> +contains the information required to map from a phandle to a tree location.
>> diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
>> index 1a13f5b..aa315c4 100644
>> --- a/drivers/of/Kconfig
>> +++ b/drivers/of/Kconfig
>> @@ -83,4 +83,11 @@ config OF_RESERVED_MEM
>> config OF_RESOLVE
>> 	bool
>> 
>> +config OF_OVERLAY
>> +	bool
>> +	depends on OF
>> +	select OF_DYNAMIC
>> +	select OF_DEVICE
>> +	select OF_RESOLVE
>> +
>> endmenu # OF
>> diff --git a/drivers/of/Makefile b/drivers/of/Makefile
>> index ca9209c..1bfe462 100644
>> --- a/drivers/of/Makefile
>> +++ b/drivers/of/Makefile
>> @@ -14,6 +14,7 @@ obj-$(CONFIG_OF_PCI_IRQ)  += of_pci_irq.o
>> obj-$(CONFIG_OF_MTD)	+= of_mtd.o
>> obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
>> obj-$(CONFIG_OF_RESOLVE)  += resolver.o
>> +obj-$(CONFIG_OF_OVERLAY) += overlay.o
>> 
>> CFLAGS_fdt.o = -I$(src)/../../scripts/dtc/libfdt
>> CFLAGS_fdt_address.o = -I$(src)/../../scripts/dtc/libfdt
>> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
>> new file mode 100644
>> index 0000000..ec7675d
>> --- /dev/null
>> +++ b/drivers/of/overlay.c
>> @@ -0,0 +1,656 @@
>> +/*
>> + * Functions for working with device tree overlays
>> + *
>> + * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
>> + * Copyright (C) 2012 Texas Instruments Inc.
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License
>> + * version 2 as published by the Free Software Foundation.
>> + */
>> +#undef DEBUG
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/string.h>
>> +#include <linux/ctype.h>
>> +#include <linux/errno.h>
>> +#include <linux/string.h>
>> +#include <linux/slab.h>
>> +#include <linux/err.h>
>> +
>> +#include "of_private.h"
>> +
>> +/**
>> + * struct of_overlay_info	- Holds a single overlay info
>> + * @target:	target of the overlay operation
>> + * @overlay:	pointer to the overlay contents node
>> + *
>> + * Holds a single overlay state, including all the overlay logs &
>> + * records.
>> + */
>> +struct of_overlay_info {
>> +	struct device_node *target;
>> +	struct device_node *overlay;
>> +};
>> +
>> +/**
>> + * struct of_overlay - Holds a complete overlay transaction
>> + * @node:	List on which we are located
>> + * @count:	Count of ovinfo structures
>> + * @ovinfo:	Overlay info array (count size)
>> + * @le_list:	List of the overlay logs
> 
> The documentation is out-of-date. Please supply a fixup patch.
> 

OK

>> + *
>> + * Holds a complete overlay transaction
>> + */
>> +struct of_overlay {
>> +	int id;
>> +	struct list_head node;
>> +	int count;
>> +	struct of_overlay_info *ovinfo_tab;
>> +	struct of_changeset cset;
>> +};
>> +
>> +static int of_overlay_apply_one(struct of_overlay *ov,
>> +		struct device_node *target, const struct device_node *overlay);
>> +
>> +static int of_overlay_apply_single_property(struct of_overlay *ov,
>> +		struct device_node *target, struct property *prop)
>> +{
>> +	struct property *propn, *tprop;
>> +
>> +	/* NOTE: Multiple changes of single properties not supported */
>> +	tprop = of_find_property(target, prop->name, NULL);
>> +
>> +	/* special properties are not meant to be updated (silent NOP) */
>> +	if (tprop &&
>> +		(!of_prop_cmp(prop->name, "name") ||
>> +		 !of_prop_cmp(prop->name, "phandle") ||
>> +		 !of_prop_cmp(prop->name, "linux,phandle")))
>> +		return 0;
> 
> What is the reason for these tests being conditional on the presence of
> the property in the node?
> 

We want to avoid updating those properties when updating an existing node.
The case where we insert these properties is valid when adding a new node. 

>> +
>> +	propn = __of_prop_dup(prop, GFP_KERNEL);
>> +	if (propn == NULL)
>> +		return -ENOMEM;
>> +
>> +	/* not found? add */
>> +	if (tprop == NULL)
>> +		return of_changeset_add_property(&ov->cset, target, propn);
>> +
>> +	/* found? update */
>> +	return of_changeset_update_property(&ov->cset, target, propn, tprop);
>> +}
>> +
>> +static int of_overlay_apply_single_device_node(struct of_overlay *ov,
>> +		struct device_node *target, struct device_node *child)
>> +{
>> +	const char *cname;
>> +	struct device_node *tchild;
>> +	char *full_name;
>> +	const char *suffix;
>> +	int ret;
>> +
>> +	/* special case for nodes with a suffix */
>> +	suffix = strrchr(child->full_name, '@');
>> +	if (suffix != NULL) {
>> +		cname = kbasename(child->full_name);
>> +		if (cname == NULL)
>> +			return -ENOMEM;
>> +	} else
>> +		cname = child->name;
> 
> So, if it has a unit address suffix, kbasename is used. If it doesn't
> have a suffix, child->name is used because it is cheaper that using
> kbasename? If that's the reason, I don't think the code complexity is
> worth it since the cost should be negligable. Can kbasename() be used
> always?
> 

Yes, that is the reason. kbasename can be used each time (I have to verify
to be sure).

>> +
>> +	ret = 0;
>> +
>> +	/* NOTE: Multiple mods of created nodes not supported */
>> +	tchild = of_get_child_by_name(target, cname);
>> +	if (tchild != NULL) {
>> +
>> +		/* apply overlay recursively */
>> +		ret = of_overlay_apply_one(ov, tchild,
>> +				child);
>> +
>> +		of_node_put(tchild);
>> +
>> +	} else {
>> +		full_name = kasprintf(GFP_KERNEL, "%s/%s",
>> +				target->full_name, cname);
>> +		if (full_name == NULL)
>> +			return -ENOMEM;
>> +
>> +		/* create empty tree as a target */
>> +		tchild = __of_node_alloc(full_name, GFP_KERNEL);
>> +
>> +		/* free either way */
>> +		kfree(full_name);
>> +
>> +		if (tchild == NULL)
>> +			return -ENOMEM;
>> +
>> +		/* point to parent */
>> +		tchild->parent = target;
> 
> As discussed on IRC, if a node doesn't already exist in the tree, then
> the properties can be duplicated with the node. There is no need to do a
> of_changeset_add_property() on each and every node. That just makes the
> load on notifiers a lot heavier and adds more processing on add and
> remove.

In theory yes. I have to verify whether this approach works.

> 
>> +
>> +		/* apply the overlay */
>> +		ret = of_overlay_apply_one(ov, tchild,
>> +				child);
>> +
>> +		/* attach the node afterwards */
>> +		if (!ret)
>> +			ret = of_changeset_attach_node(&ov->cset, tchild);
> 
> It looks to me like the parent is getting added /after/ the child is
> added in the changeset stack. That doesn't look right to me. Wouldn't
> that also mean that the child node get registered on sysfs after the
> parent nodes?
> 

This is done on purpose. Remember that nothing is added to sysfs at this
point; you have to commit the changeset for sysfs nodes to be created.

Performing the node attach after performing the recursive call allows
us to get rid of the special casing for properties; the phandle ones in
particular.

>> +
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +/*
>> + * Apply a single overlay node recursively.
>> + *
>> + * Note that the in case of an error the target node is left
>> + * in a inconsistent state. Error recovery should be performed
>> + * by using the tree changes list.
>> + */
>> +static int of_overlay_apply_one(struct of_overlay *ov,
>> +		struct device_node *target, const struct device_node *overlay)
>> +{
>> +	struct device_node *child;
>> +	struct property *prop;
>> +	int prev_avail, prop_avail, pass;
>> +	int ret;
>> +
>> +	/*
>> +	 * Special consideration for status properties
>> +	 *
>> +	 * In order to make status property changes work
>> +	 * we have the following cases:
>> +	 *
>> +	 * Enabled device with status change to 'disabled'
>> +	 *   -> Status property must be first on the record list
>> +	 *
>> +	 * Disabled device with status change to 'okay'
>> +	 *   -> Status property must be last in the record list
>> +	 *
>> +	 * That way we don't need a special notifier for
>> +	 * device status change, a simple notifier on the status
>> +	 * property is enough.
>> +	 *
>> +	 */
> 
> Is this true anymore? The notifiers are held back until all the changes
> are made to the tree, so regardless of what order the notifiers are
> emitted in, the tree will always be in the correct state.
> 

The tree will be in the correct state. The semantics are iffy regarding
what happens when the order of notifiers is not defined.

In theory it shouldn’t matter, so I’ll try to remove this.

>> +
>> +	/* note that we require the existence of a status property */
>> +	prev_avail = of_device_is_available(target) &&
>> +		of_find_property(target,
>> +				"compatible", NULL) &&
>> +		of_find_property(target,
>> +				"status", NULL);
>> +
>> +	/* we make two passes */
>> +	for (pass = 1; pass <= 2; pass++) {
>> +
>> +		for_each_property_of_node(overlay, prop) {
>> +
>> +			prop_avail = -1;
>> +
>> +			if (of_prop_cmp(prop->name, "status") == 0)
>> +				prop_avail = strcmp(prop->value, "okay") == 0 ||
>> +						strcmp(prop->value, "ok") == 0;
>> +
>> +			/* skip activation property */
>> +			if (prev_avail == 0) {
>> +				/* 0 -> 1, pass #1, skip */
>> +				if (pass == 1) {
>> +					if (prop_avail == 1)
>> +						continue;
>> +				} else {
>> +					/* 0 -> 1, pass #2, process */
>> +					if (prop_avail != 1)
>> +						continue;
>> +				}
>> +			} else {
>> +				if (pass == 1) {
>> +					/* 1 -> 0, pass #1, process */
>> +					if (prop_avail != 0)
>> +						continue;
>> +				} else {
>> +					/* 1 -> 0, pass #2, skip */
>> +					if (prop_avail == 0)
>> +						continue;
>> +				}
>> +			}
>> +
>> +			ret = of_overlay_apply_single_property(ov,
>> +					target, prop);
>> +			if (ret != 0) {
>> +				pr_err("%s: Failed to apply prop @%s/%s\n",
>> +						__func__, target->full_name,
>> +						prop->name);
>> +				return ret;
>> +			}
>> +		}
>> +	}
>> +
>> +	for_each_child_of_node(overlay, child) {
>> +		ret = of_overlay_apply_single_device_node(ov, target, child);
>> +		if (ret != 0) {
>> +			pr_err("%s: Failed to apply single node @%s/%s\n",
>> +					__func__, target->full_name,
>> +					child->name);
>> +			return ret;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * of_overlay_apply - Apply @count overlays pointed at by @ovinfo_tab
>> + * @ov:		Overlay to apply
>> + *
>> + * Applies the overlays given, while handling all error conditions
>> + * appropriately. Either the operation succeeds, or if it fails the
>> + * live tree is reverted to the state before the attempt.
>> + * Returns 0, or an error if the overlay attempt failed.
>> + */
>> +static int of_overlay_apply(struct of_overlay *ov)
>> +{
>> +	struct of_overlay_info *ovinfo;
>> +	int i, err;
>> +
>> +	/* first we apply the overlays atomically */
>> +	for (i = 0; i < ov->count; i++) {
>> +
>> +		ovinfo = &ov->ovinfo_tab[i];
>> +
>> +		err = of_overlay_apply_one(ov, ovinfo->target,
>> +				ovinfo->overlay);
>> +		if (err != 0) {
>> +			pr_err("%s: overlay failed '%s'\n",
>> +				__func__, ovinfo->target->full_name);
>> +			return err;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/*
>> + * Find the target node using a number of different strategies
>> + * in order of preference
>> + *
>> + * "target" property containing the phandle of the target
>> + * "target-path" property containing the path of the target
>> + *
>> + */
>> +static struct device_node *find_target_node(struct device_node *info_node)
>> +{
>> +	const char *path;
>> +	u32 val;
>> +	int ret;
>> +
>> +	/* first try to go by using the target as a phandle */
>> +	ret = of_property_read_u32(info_node, "target", &val);
>> +	if (ret == 0)
>> +		return of_find_node_by_phandle(val);
>> +
>> +	/* now try to locate by path */
>> +	ret = of_property_read_string(info_node, "target-path", &path);
>> +	if (ret == 0)
>> +		return of_find_node_by_path(path);
>> +
>> +	pr_err("%s: Failed to find target for node %p (%s)\n", __func__,
>> +			info_node, info_node->name);
>> +
>> +	return NULL;
>> +}
>> +
>> +/**
>> + * of_fill_overlay_info	- Fill an overlay info structure
>> + * @ov		Overlay to fill
>> + * @info_node:	Device node containing the overlay
>> + * @ovinfo:	Pointer to the overlay info structure to fill
>> + *
>> + * Fills an overlay info structure with the overlay information
>> + * from a device node. This device node must have a target property
>> + * which contains a phandle of the overlay target node, and an
>> + * __overlay__ child node which has the overlay contents.
>> + * Both ovinfo->target & ovinfo->overlay have their references taken.
>> + *
>> + * Returns 0 on success, or a negative error value.
>> + */
>> +static int of_fill_overlay_info(struct of_overlay *ov,
>> +		struct device_node *info_node, struct of_overlay_info *ovinfo)
>> +{
>> +	ovinfo->overlay = of_get_child_by_name(info_node, "__overlay__");
>> +	if (ovinfo->overlay == NULL)
>> +		goto err_fail;
>> +
>> +	ovinfo->target = find_target_node(info_node);
>> +	if (ovinfo->target == NULL)
>> +		goto err_fail;
>> +
>> +	return 0;
>> +
>> +err_fail:
>> +	of_node_put(ovinfo->target);
>> +	of_node_put(ovinfo->overlay);
>> +
>> +	memset(ovinfo, 0, sizeof(*ovinfo));
>> +	return -EINVAL;
>> +}
>> +
>> +/**
>> + * of_build_overlay_info	- Build an overlay info array
>> + * @ov		Overlay to build
>> + * @tree:	Device node containing all the overlays
>> + *
>> + * Helper function that given a tree containing overlay information,
>> + * allocates and builds an overlay info array containing it, ready
>> + * for use using of_overlay_apply.
>> + *
>> + * Returns 0 on success with the @cntp @ovinfop pointers valid,
>> + * while on error a negative error value is returned.
>> + */
>> +static int of_build_overlay_info(struct of_overlay *ov,
>> +		struct device_node *tree)
>> +{
>> +	struct device_node *node;
>> +	struct of_overlay_info *ovinfo;
>> +	int cnt, err;
>> +
>> +	/* worst case; every child is a node */
>> +	cnt = 0;
>> +	for_each_child_of_node(tree, node)
>> +		cnt++;
>> +
>> +	ovinfo = kcalloc(cnt, sizeof(*ovinfo), GFP_KERNEL);
>> +	if (ovinfo == NULL)
>> +		return -ENOMEM;
>> +
>> +	cnt = 0;
>> +	for_each_child_of_node(tree, node) {
>> +
>> +		memset(&ovinfo[cnt], 0, sizeof(*ovinfo));
>> +		err = of_fill_overlay_info(ov, node, &ovinfo[cnt]);
>> +		if (err == 0)
>> +			cnt++;
>> +	}
>> +
>> +	/* if nothing filled, return error */
>> +	if (cnt == 0) {
>> +		kfree(ovinfo);
>> +		return -ENODEV;
>> +	}
>> +
>> +	ov->count = cnt;
>> +	ov->ovinfo_tab = ovinfo;
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * of_free_overlay_info	- Free an overlay info array
>> + * @ov		Overlay to free the overlay info from
>> + * @ovinfo_tab:	Array of overlay_info's to free
>> + *
>> + * Releases the memory of a previously allocated ovinfo array
>> + * by of_build_overlay_info.
>> + * Returns 0, or an error if the arguments are bogus.
>> + */
>> +static int of_free_overlay_info(struct of_overlay *ov)
>> +{
>> +	struct of_overlay_info *ovinfo;
>> +	int i;
>> +
>> +	/* do it in reverse */
>> +	for (i = ov->count - 1; i >= 0; i--) {
>> +		ovinfo = &ov->ovinfo_tab[i];
>> +
>> +		of_node_put(ovinfo->target);
>> +		of_node_put(ovinfo->overlay);
>> +	}
>> +	kfree(ov->ovinfo_tab);
>> +
>> +	return 0;
>> +}
>> +
>> +static LIST_HEAD(ov_list);
>> +static DEFINE_MUTEX(ov_lock);
>> +static DEFINE_IDR(ov_idr);
>> +
>> +/**
>> + * of_overlay_create	- Create and apply an overlay
>> + * @tree:	Device node containing all the overlays
>> + *
>> + * Creates and applies an overlay while also keeping track
>> + * of the overlay in a list. This list can be used to prevent
>> + * illegal overlay removals.
>> + *
>> + * Returns the id of the created overlay, or an negative error number
>> + */
>> +int of_overlay_create(struct device_node *tree)
>> +{
>> +	struct of_overlay *ov;
>> +	int err, id;
>> +
>> +	/* allocate the overlay structure */
>> +	ov = kzalloc(sizeof(*ov), GFP_KERNEL);
>> +	if (ov == NULL)
>> +		return -ENOMEM;
>> +	ov->id = -1;
>> +
>> +	INIT_LIST_HEAD(&ov->node);
>> +	mutex_lock(&ov_lock);
> 
> Holding the of_mutex lock over the entire operation is probably
> sufficent. I don't think the locking needs the complexity of multiple
> mutexes.
> 

Hmm, probably yes. My only concern is that we’ll need to hold of_mutex
for as long as we’re performing the overlay_removal_check() below.

This is potentially an expensive operation during which no other
changes to the tree can occur.

If that’s fine I’ll go and remove the ov_lock.

>> +
>> +	of_changeset_init(&ov->cset);
>> +
>> +	id = idr_alloc(&ov_idr, ov, 0, 0, GFP_KERNEL);
>> +	if (id < 0) {
>> +		pr_err("%s: idr_alloc() failed for tree@%s\n",
>> +				__func__, tree->full_name);
>> +		err = id;
>> +		goto err_destroy_trans;
>> +	}
>> +	ov->id = id;
>> +
>> +	/* build the overlay info structures */
>> +	err = of_build_overlay_info(ov, tree);
>> +	if (err) {
>> +		pr_err("%s: of_build_overlay_info() failed for tree@%s\n",
>> +				__func__, tree->full_name);
>> +		goto err_free_idr;
>> +	}
>> +
>> +	mutex_lock(&of_mutex);
>> +
>> +	/* apply the overlay */
>> +	err = of_overlay_apply(ov);
>> +	if (err) {
>> +		pr_err("%s: of_overlay_apply() failed for tree@%s\n",
>> +				__func__, tree->full_name);
>> +		goto err_abort_trans;
>> +	}
>> +
>> +	/* apply the changeset */
>> +	err = of_changeset_apply(&ov->cset);
>> +	if (err) {
>> +		pr_err("%s: of_changeset_apply() failed for tree@%s\n",
>> +				__func__, tree->full_name);
>> +		goto err_revert_overlay;
>> +	}
>> +
>> +	mutex_unlock(&of_mutex);
>> +
>> +	/* add to the tail of the overlay list */
>> +	list_add_tail(&ov->node, &ov_list);
>> +
>> +	mutex_unlock(&ov_lock);
>> +
>> +	return id;
>> +
>> +err_revert_overlay:
>> +err_abort_trans:
>> +	of_free_overlay_info(ov);
>> +	mutex_unlock(&of_mutex);
>> +err_free_idr:
>> +	idr_remove(&ov_idr, ov->id);
>> +err_destroy_trans:
>> +	of_changeset_destroy(&ov->cset);
>> +	mutex_unlock(&ov_lock);
>> +	kfree(ov);
>> +
>> +	return err;
>> +}
>> +EXPORT_SYMBOL_GPL(of_overlay_create);
>> +
>> +/* check whether the given node, lies under the given tree */
>> +static int overlay_subtree_check(struct device_node *tree,
>> +		struct device_node *dn)
>> +{
>> +	struct device_node *child;
>> +
>> +	/* match? */
>> +	if (tree == dn)
>> +		return 1;
>> +
>> +	for_each_child_of_node(tree, child) {
>> +		if (overlay_subtree_check(child, dn))
>> +			return 1;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/* check whether this overlay is the topmost */
>> +static int overlay_is_topmost(struct of_overlay *ov, struct device_node *dn)
>> +{
>> +	struct of_overlay *ovt;
>> +	struct of_changeset_entry *ce;
>> +
>> +	list_for_each_entry_reverse(ovt, &ov_list, node) {
>> +
>> +		/* if we hit ourselves, we're done */
>> +		if (ovt == ov)
>> +			break;
>> +
>> +		/* check against each subtree affected by this overlay */
>> +		list_for_each_entry(ce, &ovt->cset.entries, node) {
>> +			if (overlay_subtree_check(ce->np, dn)) {
>> +				pr_err("%s: #%d clashes #%d @%s\n",
>> +					__func__, ov->id, ovt->id,
>> +					dn->full_name);
>> +				return 0;
>> +			}
>> +		}
>> +	}
>> +
>> +	/* overlay is topmost */
>> +	return 1;
>> +}
>> +
>> +/*
>> + * We can safely remove the overlay only if it's the top-most one.
>> + * Newly applied overlays are inserted at the tail of the overlay list,
>> + * so a top most overlay is the one that is closest to the tail.
>> + *
>> + * The topmost check is done by exploiting this property. For each
>> + * affected device node in the log list we check if this overlay is
>> + * the one closest to the tail. If another overlay has affected this
>> + * device node and is closest to the tail, then removal is not permited.
>> + */
>> +static int overlay_removal_is_ok(struct of_overlay *ov)
>> +{
>> +	struct of_changeset_entry *ce;
>> +
>> +	list_for_each_entry(ce, &ov->cset.entries, node) {
>> +		if (!overlay_is_topmost(ov, ce->np)) {
>> +			pr_err("%s: overlay #%d is not topmost\n",
>> +					__func__, ov->id);
>> +			return 0;
>> +		}
>> +	}
>> +
>> +	return 1;
>> +}
>> +
>> +/**
>> + * of_overlay_destroy	- Removes an overlay
>> + * @id:	Overlay id number returned by a previous call to of_overlay_create
>> + *
>> + * Removes an overlay if it is permissible.
>> + *
>> + * Returns 0 on success, or an negative error number
>> + */
>> +int of_overlay_destroy(int id)
>> +{
>> +	struct of_overlay *ov;
>> +	int err;
>> +
>> +	mutex_lock(&ov_lock);
>> +	ov = idr_find(&ov_idr, id);
>> +	if (ov == NULL) {
>> +		err = -ENODEV;
>> +		pr_err("%s: Could not find overlay #%d\n",
>> +				__func__, id);
>> +		goto out;
>> +	}
>> +
>> +	/* check whether the overlay is safe to remove */
>> +	if (!overlay_removal_is_ok(ov)) {
>> +		err = -EBUSY;
>> +		pr_err("%s: removal check failed for overlay #%d\n",
>> +				__func__, id);
>> +		goto out;
>> +	}
>> +
>> +
>> +	list_del(&ov->node);
>> +
>> +	mutex_lock(&of_mutex);
>> +	of_changeset_revert(&ov->cset);
>> +	mutex_unlock(&of_mutex);
>> +
>> +	of_free_overlay_info(ov);
>> +	idr_remove(&ov_idr, id);
>> +	of_changeset_destroy(&ov->cset);
>> +	kfree(ov);
>> +
>> +	err = 0;
>> +
>> +out:
>> +	mutex_unlock(&ov_lock);
>> +
>> +	return err;
>> +}
>> +EXPORT_SYMBOL_GPL(of_overlay_destroy);
>> +
>> +/**
>> + * of_overlay_destroy_all	- Removes all overlays from the system
>> + *
>> + * Removes all overlays from the system in the correct order.
>> + *
>> + * Returns 0 on success, or an negative error number
>> + */
>> +int of_overlay_destroy_all(void)
>> +{
>> +	struct of_overlay *ov, *ovn;
>> +
>> +	mutex_lock(&ov_lock);
>> +
>> +	/* the tail of list is guaranteed to be safe to remove */
>> +	list_for_each_entry_safe_reverse(ov, ovn, &ov_list, node) {
>> +		list_del(&ov->node);
>> +
>> +		mutex_lock(&of_mutex);
>> +		of_changeset_revert(&ov->cset);
>> +		mutex_unlock(&of_mutex);
>> +
>> +		of_free_overlay_info(ov);
>> +		idr_remove(&ov_idr, ov->id);
>> +		kfree(ov);
>> +	}
>> +
>> +
>> +	mutex_unlock(&ov_lock);
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(of_overlay_destroy_all);
>> diff --git a/include/linux/of.h b/include/linux/of.h
>> index 9ff1ec5..9e3e545 100644
>> --- a/include/linux/of.h
>> +++ b/include/linux/of.h
>> @@ -23,6 +23,7 @@
>> #include <linux/spinlock.h>
>> #include <linux/topology.h>
>> #include <linux/notifier.h>
>> +#include <linux/list.h>
>> 
>> #include <asm/byteorder.h>
>> #include <asm/errno.h>
>> @@ -873,4 +874,34 @@ static inline int of_changeset_update_property(struct of_changeset *ocs,
>> /* CONFIG_OF_RESOLVE api */
>> extern int of_resolve_phandles(struct device_node *tree);
>> 
>> +/**
>> + * Overlay support
>> + */
>> +
>> +#ifdef CONFIG_OF_OVERLAY
>> +
>> +/* ID based overlays; the API for external users */
>> +int of_overlay_create(struct device_node *tree);
>> +int of_overlay_destroy(int id);
>> +int of_overlay_destroy_all(void);
>> +
>> +#else
>> +
>> +static inline int of_overlay_create(struct device_node *tree)
>> +{
>> +	return -ENOTSUPP;
>> +}
>> +
>> +static inline int of_overlay_destroy(int id)
>> +{
>> +	return -ENOTSUPP;
>> +}
>> +
>> +static inline int of_overlay_destroy_all(void)
>> +{
>> +	return -ENOTSUPP;
>> +}
>> +
>> +#endif
>> +
>> #endif /* _LINUX_OF_H */
>> -- 
>> 1.7.12

I’ll try to generate an incremental patch today if possible.

Regards

— Pantelis

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Re: [PATCH v8 1/8] OF: Introduce DT overlay support. (v2)

[Grant Likely]

On Mon, Nov 17, 2014 at 2:35 PM, Pantelis Antoniou
<pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org> wrote:
> Hi Grant,
>
>> On Nov 14, 2014, at 01:36 , Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> wrote:
>>
>> On Tue, 28 Oct 2014 22:35:58 +0200
>> , Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
>> wrote:
>>> Introduce DT overlay support.
>>>
>>> Makes it possible to dynamically overlay a part of the kernel's
>>> tree with another tree that's been dynamically loaded.
>>> Removal of nodes and properties is also possible.
>>>
>>> The hard part of applying and reverting the overlay is performed
>>> using changesets.
>>>
>>> Documentation about internal and APIs is provided in
>>>      Documentation/devicetree/overlay-notes.txt
>>
>> Hi Pantelis,
>>
>> Comments below. I've picked up this patch, the selftest patch, and the
>> platform bus patch into my working tree. You can supply me with fixup
>> patches for the comments below.
>>
>> Hopefully I'll get my tree published to a test branch tomorrow .
>>
>>>
>>> Changes since v1:
>>> - Drop delete capability using '-' prefix. The '-' prefixed names
>>> are valid properties and nodes and there is no need for it just yet.
>>> - Do not update special properties - name & phandle ones.
>>> - Change order of node attachment, so that the special property update
>>> works.
>>>
>>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
>>> ---
>>> Documentation/devicetree/overlay-notes.txt | 137 ++++++
>>> drivers/of/Kconfig                         |   7 +
>>> drivers/of/Makefile                        |   1 +
>>> drivers/of/overlay.c                       | 656 +++++++++++++++++++++++++++++
>>> include/linux/of.h                         |  31 ++
>>> 5 files changed, 832 insertions(+)
>>> create mode 100644 Documentation/devicetree/overlay-notes.txt
>>> create mode 100644 drivers/of/overlay.c
>>>
>>> diff --git a/Documentation/devicetree/overlay-notes.txt b/Documentation/devicetree/overlay-notes.txt
>>> new file mode 100644
>>> index 0000000..b060bd7
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/overlay-notes.txt
>>> @@ -0,0 +1,137 @@
>>> +Device Tree Overlay Notes
>>> +-------------------------
>>> +
>>> +This document describes the implementation of the in-kernel
>>> +device tree overlay functionality residing in drivers/of/overlay.c and is a
>>> +companion document to Documentation/devicetree/dt-object-internal.txt[1] &
>>> +Documentation/devicetree/dynamic-resolution-notes.txt[2]
>>> +
>>> +How overlays work
>>> +-----------------
>>> +
>>> +A Device Tree's overlay purpose is to modify the kernel's live tree, and
>>> +have the modification affecting the state of the the kernel in a way that
>>> +is reflecting the changes.
>>> +Since the kernel mainly deals with devices, any new device node that result
>>> +in an active device should have it created while if the device node is either
>>> +disabled or removed all together, the affected device should be deregistered.
>>> +
>>> +Lets take an example where we have a foo board with the following base tree
>>> +which is taken from [1].
>>> +
>>> +---- foo.dts -----------------------------------------------------------------
>>> +    /* FOO platform */
>>> +    / {
>>> +            compatible = "corp,foo";
>>> +
>>> +            /* shared resources */
>>> +            res: res {
>>> +            };
>>> +
>>> +            /* On chip peripherals */
>>> +            ocp: ocp {
>>> +                    /* peripherals that are always instantiated */
>>> +                    peripheral1 { ... };
>>> +            }
>>> +    };
>>> +---- foo.dts -----------------------------------------------------------------
>>> +
>>> +The overlay bar.dts, when loaded (and resolved as described in [2]) should
>>> +
>>> +---- bar.dts -----------------------------------------------------------------
>>> +/plugin/;   /* allow undefined label references and record them */
>>> +/ {
>>> +    ....    /* various properties for loader use; i.e. part id etc. */
>>> +    fragment@0 {
>>> +            target = <&ocp>;
>>> +            __overlay__ {
>>> +                    /* bar peripheral */
>>> +                    bar {
>>> +                            compatible = "corp,bar";
>>> +                            ... /* various properties and child nodes */
>>> +                    }
>>> +            };
>>> +    };
>>> +};
>>> +---- bar.dts -----------------------------------------------------------------
>>> +
>>> +result in foo+bar.dts
>>> +
>>> +---- foo+bar.dts -------------------------------------------------------------
>>> +    /* FOO platform + bar peripheral */
>>> +    / {
>>> +            compatible = "corp,foo";
>>> +
>>> +            /* shared resources */
>>> +            res: res {
>>> +            };
>>> +
>>> +            /* On chip peripherals */
>>> +            ocp: ocp {
>>> +                    /* peripherals that are always instantiated */
>>> +                    peripheral1 { ... };
>>> +
>>> +                    /* bar peripheral */
>>> +                    bar {
>>> +                            compatible = "corp,bar";
>>> +                            ... /* various properties and child nodes */
>>> +                    }
>>> +            }
>>> +    };
>>> +---- foo+bar.dts -------------------------------------------------------------
>>> +
>>> +As a result of the the overlay, a new device node (bar) has been created
>>> +so a bar platform device will be registered and if a matching device driver
>>> +is loaded the device will be created as expected.
>>> +
>>> +Overlay in-kernel API
>>> +--------------------------------
>>> +
>>> +The API is quite easy to use.
>>> +
>>> +1. Call of_overlay_create() to create and apply an overlay. The return value
>>> +is a cookie identifying this overlay.
>>> +
>>> +2. Call of_overlay_destroy() to remove and cleanup the overlay previously
>>> +created via the call to of_overlay_create(). Removal of an overlay that
>>> +is stacked by another will not be permitted.
>>> +
>>> +Finally, if you need to remove all overlays in one-go, just call
>>> +of_overlay_destroy_all() which will remove every single one in the correct
>>> +order.
>>> +
>>> +Overlay DTS Format
>>> +------------------
>>> +
>>> +The DTS of an overlay should have the following format:
>>> +
>>> +{
>>> +    /* ignored properties by the overlay */
>>> +
>>> +    fragment@0 {    /* first child node */
>>> +
>>> +            target=<phandle>;       /* phandle target of the overlay */
>>> +    or
>>> +            target-path="/path";    /* target path of the overlay */
>>> +
>>> +            __overlay__ {
>>> +                    property-a;     /* add property-a to the target */
>>> +                    -property-b;    /* remove property-b from target */
>>> +                    node-a {        /* add to an existing, or create a node-a */
>>> +                            ...
>>> +                    };
>>> +                    -node-b {       /* remove an existing node-b */
>>> +                            ...
>>> +                    };
>>
>> -property-b and -node-b need to be removed from the example.
>>
>
> OK
>
>>> +            };
>>> +    }
>>> +    fragment@1 {    /* second child node */
>>> +            ...
>>> +    };
>>> +    /* more fragments follow */
>>> +}
>>> +
>>> +Using the non-phandle based target method allows one to use a base DT which does
>>> +not contain a __symbols__ node, i.e. it was not compiled with the -@ option.
>>> +The __symbols__ node is only required for the target=<phandle> method, since it
>>> +contains the information required to map from a phandle to a tree location.
>>> diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
>>> index 1a13f5b..aa315c4 100644
>>> --- a/drivers/of/Kconfig
>>> +++ b/drivers/of/Kconfig
>>> @@ -83,4 +83,11 @@ config OF_RESERVED_MEM
>>> config OF_RESOLVE
>>>      bool
>>>
>>> +config OF_OVERLAY
>>> +    bool
>>> +    depends on OF
>>> +    select OF_DYNAMIC
>>> +    select OF_DEVICE
>>> +    select OF_RESOLVE
>>> +
>>> endmenu # OF
>>> diff --git a/drivers/of/Makefile b/drivers/of/Makefile
>>> index ca9209c..1bfe462 100644
>>> --- a/drivers/of/Makefile
>>> +++ b/drivers/of/Makefile
>>> @@ -14,6 +14,7 @@ obj-$(CONFIG_OF_PCI_IRQ)  += of_pci_irq.o
>>> obj-$(CONFIG_OF_MTD) += of_mtd.o
>>> obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
>>> obj-$(CONFIG_OF_RESOLVE)  += resolver.o
>>> +obj-$(CONFIG_OF_OVERLAY) += overlay.o
>>>
>>> CFLAGS_fdt.o = -I$(src)/../../scripts/dtc/libfdt
>>> CFLAGS_fdt_address.o = -I$(src)/../../scripts/dtc/libfdt
>>> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
>>> new file mode 100644
>>> index 0000000..ec7675d
>>> --- /dev/null
>>> +++ b/drivers/of/overlay.c
>>> @@ -0,0 +1,656 @@
>>> +/*
>>> + * Functions for working with device tree overlays
>>> + *
>>> + * Copyright (C) 2012 Pantelis Antoniou <panto-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
>>> + * Copyright (C) 2012 Texas Instruments Inc.
>>> + *
>>> + * This program is free software; you can redistribute it and/or
>>> + * modify it under the terms of the GNU General Public License
>>> + * version 2 as published by the Free Software Foundation.
>>> + */
>>> +#undef DEBUG
>>> +#include <linux/kernel.h>
>>> +#include <linux/module.h>
>>> +#include <linux/of.h>
>>> +#include <linux/of_device.h>
>>> +#include <linux/string.h>
>>> +#include <linux/ctype.h>
>>> +#include <linux/errno.h>
>>> +#include <linux/string.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/err.h>
>>> +
>>> +#include "of_private.h"
>>> +
>>> +/**
>>> + * struct of_overlay_info   - Holds a single overlay info
>>> + * @target: target of the overlay operation
>>> + * @overlay:        pointer to the overlay contents node
>>> + *
>>> + * Holds a single overlay state, including all the overlay logs &
>>> + * records.
>>> + */
>>> +struct of_overlay_info {
>>> +    struct device_node *target;
>>> +    struct device_node *overlay;
>>> +};
>>> +
>>> +/**
>>> + * struct of_overlay - Holds a complete overlay transaction
>>> + * @node:   List on which we are located
>>> + * @count:  Count of ovinfo structures
>>> + * @ovinfo: Overlay info array (count size)
>>> + * @le_list:        List of the overlay logs
>>
>> The documentation is out-of-date. Please supply a fixup patch.
>>
>
> OK
>
>>> + *
>>> + * Holds a complete overlay transaction
>>> + */
>>> +struct of_overlay {
>>> +    int id;
>>> +    struct list_head node;
>>> +    int count;
>>> +    struct of_overlay_info *ovinfo_tab;
>>> +    struct of_changeset cset;
>>> +};
>>> +
>>> +static int of_overlay_apply_one(struct of_overlay *ov,
>>> +            struct device_node *target, const struct device_node *overlay);
>>> +
>>> +static int of_overlay_apply_single_property(struct of_overlay *ov,
>>> +            struct device_node *target, struct property *prop)
>>> +{
>>> +    struct property *propn, *tprop;
>>> +
>>> +    /* NOTE: Multiple changes of single properties not supported */
>>> +    tprop = of_find_property(target, prop->name, NULL);
>>> +
>>> +    /* special properties are not meant to be updated (silent NOP) */
>>> +    if (tprop &&
>>> +            (!of_prop_cmp(prop->name, "name") ||
>>> +             !of_prop_cmp(prop->name, "phandle") ||
>>> +             !of_prop_cmp(prop->name, "linux,phandle")))
>>> +            return 0;
>>
>> What is the reason for these tests being conditional on the presence of
>> the property in the node?
>>
>
> We want to avoid updating those properties when updating an existing node.
> The case where we insert these properties is valid when adding a new node.

So the need for the test goes away if the properties are duplicated
with the code (instead of as separate changeset items), correct?

I've already got a change that duplicates the properties when adding a new node.

>
>>> +
>>> +    propn = __of_prop_dup(prop, GFP_KERNEL);
>>> +    if (propn == NULL)
>>> +            return -ENOMEM;
>>> +
>>> +    /* not found? add */
>>> +    if (tprop == NULL)
>>> +            return of_changeset_add_property(&ov->cset, target, propn);
>>> +
>>> +    /* found? update */
>>> +    return of_changeset_update_property(&ov->cset, target, propn, tprop);
>>> +}
>>> +
>>> +static int of_overlay_apply_single_device_node(struct of_overlay *ov,
>>> +            struct device_node *target, struct device_node *child)
>>> +{
>>> +    const char *cname;
>>> +    struct device_node *tchild;
>>> +    char *full_name;
>>> +    const char *suffix;
>>> +    int ret;
>>> +
>>> +    /* special case for nodes with a suffix */
>>> +    suffix = strrchr(child->full_name, '@');
>>> +    if (suffix != NULL) {
>>> +            cname = kbasename(child->full_name);
>>> +            if (cname == NULL)
>>> +                    return -ENOMEM;
>>> +    } else
>>> +            cname = child->name;
>>
>> So, if it has a unit address suffix, kbasename is used. If it doesn't
>> have a suffix, child->name is used because it is cheaper that using
>> kbasename? If that's the reason, I don't think the code complexity is
>> worth it since the cost should be negligable. Can kbasename() be used
>> always?
>>
>
> Yes, that is the reason. kbasename can be used each time (I have to verify
> to be sure).

Let's just use kbasename() here then for now, particularly if we're
going to try to be rid of assigning full_name at this point.

>
>>> +
>>> +    ret = 0;
>>> +
>>> +    /* NOTE: Multiple mods of created nodes not supported */
>>> +    tchild = of_get_child_by_name(target, cname);
>>> +    if (tchild != NULL) {
>>> +
>>> +            /* apply overlay recursively */
>>> +            ret = of_overlay_apply_one(ov, tchild,
>>> +                            child);
>>> +
>>> +            of_node_put(tchild);
>>> +
>>> +    } else {
>>> +            full_name = kasprintf(GFP_KERNEL, "%s/%s",
>>> +                            target->full_name, cname);
>>> +            if (full_name == NULL)
>>> +                    return -ENOMEM;
>>> +
>>> +            /* create empty tree as a target */
>>> +            tchild = __of_node_alloc(full_name, GFP_KERNEL);
>>> +
>>> +            /* free either way */
>>> +            kfree(full_name);
>>> +
>>> +            if (tchild == NULL)
>>> +                    return -ENOMEM;
>>> +
>>> +            /* point to parent */
>>> +            tchild->parent = target;
>>
>> As discussed on IRC, if a node doesn't already exist in the tree, then
>> the properties can be duplicated with the node. There is no need to do a
>> of_changeset_add_property() on each and every node. That just makes the
>> load on notifiers a lot heavier and adds more processing on add and
>> remove.
>
> In theory yes. I have to verify whether this approach works.
>
>>
>>> +
>>> +            /* apply the overlay */
>>> +            ret = of_overlay_apply_one(ov, tchild,
>>> +                            child);
>>> +
>>> +            /* attach the node afterwards */
>>> +            if (!ret)
>>> +                    ret = of_changeset_attach_node(&ov->cset, tchild);
>>
>> It looks to me like the parent is getting added /after/ the child is
>> added in the changeset stack. That doesn't look right to me. Wouldn't
>> that also mean that the child node get registered on sysfs after the
>> parent nodes?
>>
>
> This is done on purpose. Remember that nothing is added to sysfs at this
> point; you have to commit the changeset for sysfs nodes to be created.

But doesn't that cause the child nodes to be added to sysfs before the
parent nodes? I don't think that is valid.

> Performing the node attach after performing the recursive call allows
> us to get rid of the special casing for properties; the phandle ones in
> particular.

I think this issue goes away when properties are already added to a
new node before attach.

>
>>> +
>>> +    }
>>> +
>>> +    return ret;
>>> +}
>>> +
>>> +/*
>>> + * Apply a single overlay node recursively.
>>> + *
>>> + * Note that the in case of an error the target node is left
>>> + * in a inconsistent state. Error recovery should be performed
>>> + * by using the tree changes list.
>>> + */
>>> +static int of_overlay_apply_one(struct of_overlay *ov,
>>> +            struct device_node *target, const struct device_node *overlay)
>>> +{
>>> +    struct device_node *child;
>>> +    struct property *prop;
>>> +    int prev_avail, prop_avail, pass;
>>> +    int ret;
>>> +
>>> +    /*
>>> +     * Special consideration for status properties
>>> +     *
>>> +     * In order to make status property changes work
>>> +     * we have the following cases:
>>> +     *
>>> +     * Enabled device with status change to 'disabled'
>>> +     *   -> Status property must be first on the record list
>>> +     *
>>> +     * Disabled device with status change to 'okay'
>>> +     *   -> Status property must be last in the record list
>>> +     *
>>> +     * That way we don't need a special notifier for
>>> +     * device status change, a simple notifier on the status
>>> +     * property is enough.
>>> +     *
>>> +     */
>>
>> Is this true anymore? The notifiers are held back until all the changes
>> are made to the tree, so regardless of what order the notifiers are
>> emitted in, the tree will always be in the correct state.
>>
>
> The tree will be in the correct state. The semantics are iffy regarding
> what happens when the order of notifiers is not defined.
>
> In theory it shouldn't matter, so I'll try to remove this.

Thanks.

>
>>> +
>>> +    /* note that we require the existence of a status property */
>>> +    prev_avail = of_device_is_available(target) &&
>>> +            of_find_property(target,
>>> +                            "compatible", NULL) &&
>>> +            of_find_property(target,
>>> +                            "status", NULL);
>>> +
>>> +    /* we make two passes */
>>> +    for (pass = 1; pass <= 2; pass++) {
>>> +
>>> +            for_each_property_of_node(overlay, prop) {
>>> +
>>> +                    prop_avail = -1;
>>> +
>>> +                    if (of_prop_cmp(prop->name, "status") == 0)
>>> +                            prop_avail = strcmp(prop->value, "okay") == 0 ||
>>> +                                            strcmp(prop->value, "ok") == 0;
>>> +
>>> +                    /* skip activation property */
>>> +                    if (prev_avail == 0) {
>>> +                            /* 0 -> 1, pass #1, skip */
>>> +                            if (pass == 1) {
>>> +                                    if (prop_avail == 1)
>>> +                                            continue;
>>> +                            } else {
>>> +                                    /* 0 -> 1, pass #2, process */
>>> +                                    if (prop_avail != 1)
>>> +                                            continue;
>>> +                            }
>>> +                    } else {
>>> +                            if (pass == 1) {
>>> +                                    /* 1 -> 0, pass #1, process */
>>> +                                    if (prop_avail != 0)
>>> +                                            continue;
>>> +                            } else {
>>> +                                    /* 1 -> 0, pass #2, skip */
>>> +                                    if (prop_avail == 0)
>>> +                                            continue;
>>> +                            }
>>> +                    }
>>> +
>>> +                    ret = of_overlay_apply_single_property(ov,
>>> +                                    target, prop);
>>> +                    if (ret != 0) {
>>> +                            pr_err("%s: Failed to apply prop @%s/%s\n",
>>> +                                            __func__, target->full_name,
>>> +                                            prop->name);
>>> +                            return ret;
>>> +                    }
>>> +            }
>>> +    }
>>> +
>>> +    for_each_child_of_node(overlay, child) {
>>> +            ret = of_overlay_apply_single_device_node(ov, target, child);
>>> +            if (ret != 0) {
>>> +                    pr_err("%s: Failed to apply single node @%s/%s\n",
>>> +                                    __func__, target->full_name,
>>> +                                    child->name);
>>> +                    return ret;
>>> +            }
>>> +    }
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +/**
>>> + * of_overlay_apply - Apply @count overlays pointed at by @ovinfo_tab
>>> + * @ov:             Overlay to apply
>>> + *
>>> + * Applies the overlays given, while handling all error conditions
>>> + * appropriately. Either the operation succeeds, or if it fails the
>>> + * live tree is reverted to the state before the attempt.
>>> + * Returns 0, or an error if the overlay attempt failed.
>>> + */
>>> +static int of_overlay_apply(struct of_overlay *ov)
>>> +{
>>> +    struct of_overlay_info *ovinfo;
>>> +    int i, err;
>>> +
>>> +    /* first we apply the overlays atomically */
>>> +    for (i = 0; i < ov->count; i++) {
>>> +
>>> +            ovinfo = &ov->ovinfo_tab[i];
>>> +
>>> +            err = of_overlay_apply_one(ov, ovinfo->target,
>>> +                            ovinfo->overlay);
>>> +            if (err != 0) {
>>> +                    pr_err("%s: overlay failed '%s'\n",
>>> +                            __func__, ovinfo->target->full_name);
>>> +                    return err;
>>> +            }
>>> +    }
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +/*
>>> + * Find the target node using a number of different strategies
>>> + * in order of preference
>>> + *
>>> + * "target" property containing the phandle of the target
>>> + * "target-path" property containing the path of the target
>>> + *
>>> + */
>>> +static struct device_node *find_target_node(struct device_node *info_node)
>>> +{
>>> +    const char *path;
>>> +    u32 val;
>>> +    int ret;
>>> +
>>> +    /* first try to go by using the target as a phandle */
>>> +    ret = of_property_read_u32(info_node, "target", &val);
>>> +    if (ret == 0)
>>> +            return of_find_node_by_phandle(val);
>>> +
>>> +    /* now try to locate by path */
>>> +    ret = of_property_read_string(info_node, "target-path", &path);
>>> +    if (ret == 0)
>>> +            return of_find_node_by_path(path);
>>> +
>>> +    pr_err("%s: Failed to find target for node %p (%s)\n", __func__,
>>> +                    info_node, info_node->name);
>>> +
>>> +    return NULL;
>>> +}
>>> +
>>> +/**
>>> + * of_fill_overlay_info     - Fill an overlay info structure
>>> + * @ov              Overlay to fill
>>> + * @info_node:      Device node containing the overlay
>>> + * @ovinfo: Pointer to the overlay info structure to fill
>>> + *
>>> + * Fills an overlay info structure with the overlay information
>>> + * from a device node. This device node must have a target property
>>> + * which contains a phandle of the overlay target node, and an
>>> + * __overlay__ child node which has the overlay contents.
>>> + * Both ovinfo->target & ovinfo->overlay have their references taken.
>>> + *
>>> + * Returns 0 on success, or a negative error value.
>>> + */
>>> +static int of_fill_overlay_info(struct of_overlay *ov,
>>> +            struct device_node *info_node, struct of_overlay_info *ovinfo)
>>> +{
>>> +    ovinfo->overlay = of_get_child_by_name(info_node, "__overlay__");
>>> +    if (ovinfo->overlay == NULL)
>>> +            goto err_fail;
>>> +
>>> +    ovinfo->target = find_target_node(info_node);
>>> +    if (ovinfo->target == NULL)
>>> +            goto err_fail;
>>> +
>>> +    return 0;
>>> +
>>> +err_fail:
>>> +    of_node_put(ovinfo->target);
>>> +    of_node_put(ovinfo->overlay);
>>> +
>>> +    memset(ovinfo, 0, sizeof(*ovinfo));
>>> +    return -EINVAL;
>>> +}
>>> +
>>> +/**
>>> + * of_build_overlay_info    - Build an overlay info array
>>> + * @ov              Overlay to build
>>> + * @tree:   Device node containing all the overlays
>>> + *
>>> + * Helper function that given a tree containing overlay information,
>>> + * allocates and builds an overlay info array containing it, ready
>>> + * for use using of_overlay_apply.
>>> + *
>>> + * Returns 0 on success with the @cntp @ovinfop pointers valid,
>>> + * while on error a negative error value is returned.
>>> + */
>>> +static int of_build_overlay_info(struct of_overlay *ov,
>>> +            struct device_node *tree)
>>> +{
>>> +    struct device_node *node;
>>> +    struct of_overlay_info *ovinfo;
>>> +    int cnt, err;
>>> +
>>> +    /* worst case; every child is a node */
>>> +    cnt = 0;
>>> +    for_each_child_of_node(tree, node)
>>> +            cnt++;
>>> +
>>> +    ovinfo = kcalloc(cnt, sizeof(*ovinfo), GFP_KERNEL);
>>> +    if (ovinfo == NULL)
>>> +            return -ENOMEM;
>>> +
>>> +    cnt = 0;
>>> +    for_each_child_of_node(tree, node) {
>>> +
>>> +            memset(&ovinfo[cnt], 0, sizeof(*ovinfo));
>>> +            err = of_fill_overlay_info(ov, node, &ovinfo[cnt]);
>>> +            if (err == 0)
>>> +                    cnt++;
>>> +    }
>>> +
>>> +    /* if nothing filled, return error */
>>> +    if (cnt == 0) {
>>> +            kfree(ovinfo);
>>> +            return -ENODEV;
>>> +    }
>>> +
>>> +    ov->count = cnt;
>>> +    ov->ovinfo_tab = ovinfo;
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +/**
>>> + * of_free_overlay_info     - Free an overlay info array
>>> + * @ov              Overlay to free the overlay info from
>>> + * @ovinfo_tab:     Array of overlay_info's to free
>>> + *
>>> + * Releases the memory of a previously allocated ovinfo array
>>> + * by of_build_overlay_info.
>>> + * Returns 0, or an error if the arguments are bogus.
>>> + */
>>> +static int of_free_overlay_info(struct of_overlay *ov)
>>> +{
>>> +    struct of_overlay_info *ovinfo;
>>> +    int i;
>>> +
>>> +    /* do it in reverse */
>>> +    for (i = ov->count - 1; i >= 0; i--) {
>>> +            ovinfo = &ov->ovinfo_tab[i];
>>> +
>>> +            of_node_put(ovinfo->target);
>>> +            of_node_put(ovinfo->overlay);
>>> +    }
>>> +    kfree(ov->ovinfo_tab);
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static LIST_HEAD(ov_list);
>>> +static DEFINE_MUTEX(ov_lock);
>>> +static DEFINE_IDR(ov_idr);
>>> +
>>> +/**
>>> + * of_overlay_create        - Create and apply an overlay
>>> + * @tree:   Device node containing all the overlays
>>> + *
>>> + * Creates and applies an overlay while also keeping track
>>> + * of the overlay in a list. This list can be used to prevent
>>> + * illegal overlay removals.
>>> + *
>>> + * Returns the id of the created overlay, or an negative error number
>>> + */
>>> +int of_overlay_create(struct device_node *tree)
>>> +{
>>> +    struct of_overlay *ov;
>>> +    int err, id;
>>> +
>>> +    /* allocate the overlay structure */
>>> +    ov = kzalloc(sizeof(*ov), GFP_KERNEL);
>>> +    if (ov == NULL)
>>> +            return -ENOMEM;
>>> +    ov->id = -1;
>>> +
>>> +    INIT_LIST_HEAD(&ov->node);
>>> +    mutex_lock(&ov_lock);
>>
>> Holding the of_mutex lock over the entire operation is probably
>> sufficent. I don't think the locking needs the complexity of multiple
>> mutexes.
>>
>
> Hmm, probably yes. My only concern is that we'll need to hold of_mutex
> for as long as we're performing the overlay_removal_check() below.
>
> This is potentially an expensive operation during which no other
> changes to the tree can occur.
>
> If that's fine I'll go and remove the ov_lock.

I'm fine with that.

>
>>> +
>>> +    of_changeset_init(&ov->cset);
>>> +
>>> +    id = idr_alloc(&ov_idr, ov, 0, 0, GFP_KERNEL);
>>> +    if (id < 0) {
>>> +            pr_err("%s: idr_alloc() failed for tree@%s\n",
>>> +                            __func__, tree->full_name);
>>> +            err = id;
>>> +            goto err_destroy_trans;
>>> +    }
>>> +    ov->id = id;
>>> +
>>> +    /* build the overlay info structures */
>>> +    err = of_build_overlay_info(ov, tree);
>>> +    if (err) {
>>> +            pr_err("%s: of_build_overlay_info() failed for tree@%s\n",
>>> +                            __func__, tree->full_name);
>>> +            goto err_free_idr;
>>> +    }
>>> +
>>> +    mutex_lock(&of_mutex);
>>> +
>>> +    /* apply the overlay */
>>> +    err = of_overlay_apply(ov);
>>> +    if (err) {
>>> +            pr_err("%s: of_overlay_apply() failed for tree@%s\n",
>>> +                            __func__, tree->full_name);
>>> +            goto err_abort_trans;
>>> +    }
>>> +
>>> +    /* apply the changeset */
>>> +    err = of_changeset_apply(&ov->cset);
>>> +    if (err) {
>>> +            pr_err("%s: of_changeset_apply() failed for tree@%s\n",
>>> +                            __func__, tree->full_name);
>>> +            goto err_revert_overlay;
>>> +    }
>>> +
>>> +    mutex_unlock(&of_mutex);
>>> +
>>> +    /* add to the tail of the overlay list */
>>> +    list_add_tail(&ov->node, &ov_list);
>>> +
>>> +    mutex_unlock(&ov_lock);
>>> +
>>> +    return id;
>>> +
>>> +err_revert_overlay:
>>> +err_abort_trans:
>>> +    of_free_overlay_info(ov);
>>> +    mutex_unlock(&of_mutex);
>>> +err_free_idr:
>>> +    idr_remove(&ov_idr, ov->id);
>>> +err_destroy_trans:
>>> +    of_changeset_destroy(&ov->cset);
>>> +    mutex_unlock(&ov_lock);
>>> +    kfree(ov);
>>> +
>>> +    return err;
>>> +}
>>> +EXPORT_SYMBOL_GPL(of_overlay_create);
>>> +
>>> +/* check whether the given node, lies under the given tree */
>>> +static int overlay_subtree_check(struct device_node *tree,
>>> +            struct device_node *dn)
>>> +{
>>> +    struct device_node *child;
>>> +
>>> +    /* match? */
>>> +    if (tree == dn)
>>> +            return 1;
>>> +
>>> +    for_each_child_of_node(tree, child) {
>>> +            if (overlay_subtree_check(child, dn))
>>> +                    return 1;
>>> +    }
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +/* check whether this overlay is the topmost */
>>> +static int overlay_is_topmost(struct of_overlay *ov, struct device_node *dn)
>>> +{
>>> +    struct of_overlay *ovt;
>>> +    struct of_changeset_entry *ce;
>>> +
>>> +    list_for_each_entry_reverse(ovt, &ov_list, node) {
>>> +
>>> +            /* if we hit ourselves, we're done */
>>> +            if (ovt == ov)
>>> +                    break;
>>> +
>>> +            /* check against each subtree affected by this overlay */
>>> +            list_for_each_entry(ce, &ovt->cset.entries, node) {
>>> +                    if (overlay_subtree_check(ce->np, dn)) {
>>> +                            pr_err("%s: #%d clashes #%d @%s\n",
>>> +                                    __func__, ov->id, ovt->id,
>>> +                                    dn->full_name);
>>> +                            return 0;
>>> +                    }
>>> +            }
>>> +    }
>>> +
>>> +    /* overlay is topmost */
>>> +    return 1;
>>> +}
>>> +
>>> +/*
>>> + * We can safely remove the overlay only if it's the top-most one.
>>> + * Newly applied overlays are inserted at the tail of the overlay list,
>>> + * so a top most overlay is the one that is closest to the tail.
>>> + *
>>> + * The topmost check is done by exploiting this property. For each
>>> + * affected device node in the log list we check if this overlay is
>>> + * the one closest to the tail. If another overlay has affected this
>>> + * device node and is closest to the tail, then removal is not permited.
>>> + */
>>> +static int overlay_removal_is_ok(struct of_overlay *ov)
>>> +{
>>> +    struct of_changeset_entry *ce;
>>> +
>>> +    list_for_each_entry(ce, &ov->cset.entries, node) {
>>> +            if (!overlay_is_topmost(ov, ce->np)) {
>>> +                    pr_err("%s: overlay #%d is not topmost\n",
>>> +                                    __func__, ov->id);
>>> +                    return 0;
>>> +            }
>>> +    }
>>> +
>>> +    return 1;
>>> +}
>>> +
>>> +/**
>>> + * of_overlay_destroy       - Removes an overlay
>>> + * @id:     Overlay id number returned by a previous call to of_overlay_create
>>> + *
>>> + * Removes an overlay if it is permissible.
>>> + *
>>> + * Returns 0 on success, or an negative error number
>>> + */
>>> +int of_overlay_destroy(int id)
>>> +{
>>> +    struct of_overlay *ov;
>>> +    int err;
>>> +
>>> +    mutex_lock(&ov_lock);
>>> +    ov = idr_find(&ov_idr, id);
>>> +    if (ov == NULL) {
>>> +            err = -ENODEV;
>>> +            pr_err("%s: Could not find overlay #%d\n",
>>> +                            __func__, id);
>>> +            goto out;
>>> +    }
>>> +
>>> +    /* check whether the overlay is safe to remove */
>>> +    if (!overlay_removal_is_ok(ov)) {
>>> +            err = -EBUSY;
>>> +            pr_err("%s: removal check failed for overlay #%d\n",
>>> +                            __func__, id);
>>> +            goto out;
>>> +    }
>>> +
>>> +
>>> +    list_del(&ov->node);
>>> +
>>> +    mutex_lock(&of_mutex);
>>> +    of_changeset_revert(&ov->cset);
>>> +    mutex_unlock(&of_mutex);
>>> +
>>> +    of_free_overlay_info(ov);
>>> +    idr_remove(&ov_idr, id);
>>> +    of_changeset_destroy(&ov->cset);
>>> +    kfree(ov);
>>> +
>>> +    err = 0;
>>> +
>>> +out:
>>> +    mutex_unlock(&ov_lock);
>>> +
>>> +    return err;
>>> +}
>>> +EXPORT_SYMBOL_GPL(of_overlay_destroy);
>>> +
>>> +/**
>>> + * of_overlay_destroy_all   - Removes all overlays from the system
>>> + *
>>> + * Removes all overlays from the system in the correct order.
>>> + *
>>> + * Returns 0 on success, or an negative error number
>>> + */
>>> +int of_overlay_destroy_all(void)
>>> +{
>>> +    struct of_overlay *ov, *ovn;
>>> +
>>> +    mutex_lock(&ov_lock);
>>> +
>>> +    /* the tail of list is guaranteed to be safe to remove */
>>> +    list_for_each_entry_safe_reverse(ov, ovn, &ov_list, node) {
>>> +            list_del(&ov->node);
>>> +
>>> +            mutex_lock(&of_mutex);
>>> +            of_changeset_revert(&ov->cset);
>>> +            mutex_unlock(&of_mutex);
>>> +
>>> +            of_free_overlay_info(ov);
>>> +            idr_remove(&ov_idr, ov->id);
>>> +            kfree(ov);
>>> +    }
>>> +
>>> +
>>> +    mutex_unlock(&ov_lock);
>>> +
>>> +    return 0;
>>> +}
>>> +EXPORT_SYMBOL_GPL(of_overlay_destroy_all);
>>> diff --git a/include/linux/of.h b/include/linux/of.h
>>> index 9ff1ec5..9e3e545 100644
>>> --- a/include/linux/of.h
>>> +++ b/include/linux/of.h
>>> @@ -23,6 +23,7 @@
>>> #include <linux/spinlock.h>
>>> #include <linux/topology.h>
>>> #include <linux/notifier.h>
>>> +#include <linux/list.h>
>>>
>>> #include <asm/byteorder.h>
>>> #include <asm/errno.h>
>>> @@ -873,4 +874,34 @@ static inline int of_changeset_update_property(struct of_changeset *ocs,
>>> /* CONFIG_OF_RESOLVE api */
>>> extern int of_resolve_phandles(struct device_node *tree);
>>>
>>> +/**
>>> + * Overlay support
>>> + */
>>> +
>>> +#ifdef CONFIG_OF_OVERLAY
>>> +
>>> +/* ID based overlays; the API for external users */
>>> +int of_overlay_create(struct device_node *tree);
>>> +int of_overlay_destroy(int id);
>>> +int of_overlay_destroy_all(void);
>>> +
>>> +#else
>>> +
>>> +static inline int of_overlay_create(struct device_node *tree)
>>> +{
>>> +    return -ENOTSUPP;
>>> +}
>>> +
>>> +static inline int of_overlay_destroy(int id)
>>> +{
>>> +    return -ENOTSUPP;
>>> +}
>>> +
>>> +static inline int of_overlay_destroy_all(void)
>>> +{
>>> +    return -ENOTSUPP;
>>> +}
>>> +
>>> +#endif
>>> +
>>> #endif /* _LINUX_OF_H */
>>> --
>>> 1.7.12
>
> I'll try to generate an incremental patch today if possible.

Great!

Here's my current tree:

git://git.kernel.org/pub/scm/linux/kernel/git/glikely/linux
devicetree/next-overlay

g.
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[PATCH v8 4/8] OF: platform: Add OF notifier handler

[Pantelis Antoniou]

Add OF notifier handler needed for creating/destroying platform devices
according to dynamic runtime changes in the DT live tree.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
---
 drivers/base/platform.c     | 18 +++++++++--
 drivers/of/platform.c       | 78 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of_platform.h | 10 ++++++
 3 files changed, 103 insertions(+), 3 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index b2afc29..282bfec 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -1002,10 +1002,22 @@ int __init platform_bus_init(void)
 
 	error = device_register(&platform_bus);
 	if (error)
-		return error;
-	error =  bus_register(&platform_bus_type);
+		goto err_out;
+
+	error = bus_register(&platform_bus_type);
+	if (error)
+		goto err_unreg_dev;
+
+	error = of_platform_register_reconfig_notifier();
 	if (error)
-		device_unregister(&platform_bus);
+		goto err_unreg_bus;
+
+	return 0;
+err_unreg_bus:
+	bus_unregister(&platform_bus_type);
+err_unreg_dev:
+	device_unregister(&platform_bus);
+err_out:
 	return error;
 }
 
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 3b64d0b..aa8db92 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -546,4 +546,82 @@ void of_platform_depopulate(struct device *parent)
 }
 EXPORT_SYMBOL_GPL(of_platform_depopulate);
 
+#ifdef CONFIG_OF_DYNAMIC
+
+static struct notifier_block platform_of_notifier;
+
+static int of_platform_notify(struct notifier_block *nb,
+				unsigned long action, void *arg)
+{
+	struct platform_device *pdev_parent, *pdev;
+	struct device_node *dn;
+	int state;
+	bool children_left;
+
+	state = of_reconfig_get_state_change(action, arg);
+
+	/* no change? */
+	if (state == -1)
+		return NOTIFY_OK;
+
+	switch (action) {
+	case OF_RECONFIG_ATTACH_NODE:
+	case OF_RECONFIG_DETACH_NODE:
+		dn = arg;
+		break;
+	case OF_RECONFIG_ADD_PROPERTY:
+	case OF_RECONFIG_REMOVE_PROPERTY:
+	case OF_RECONFIG_UPDATE_PROPERTY:
+		dn = ((struct of_prop_reconfig *)arg)->dn;
+		break;
+	default:
+		return NOTIFY_OK;
+	}
+
+	if (state) {
+
+		/* verify that the parent is a bus */
+		if (!of_match_node(of_default_bus_match_table, dn->parent))
+			return NOTIFY_OK;	/* not for us */
+
+		/* pdev_parent may be NULL when no bus platform device */
+		pdev_parent = of_find_device_by_node(dn->parent);
+		pdev = of_platform_device_create(dn, NULL,
+				pdev_parent ? &pdev_parent->dev : NULL);
+		of_dev_put(pdev_parent);
+
+		if (pdev == NULL) {
+			pr_err("%s: failed to create for '%s'\n",
+					__func__, dn->full_name);
+			/* of_platform_device_create tosses the error code */
+			return notifier_from_errno(-EINVAL);
+		}
+
+	} else {
+
+		/* find our device by node */
+		pdev = of_find_device_by_node(dn);
+		if (pdev == NULL)
+			return NOTIFY_OK;	/* no? not meant for us */
+
+		/* unregister takes one ref away */
+		of_platform_device_destroy(&pdev->dev, &children_left);
+
+		/* and put the reference of the find */
+		of_dev_put(pdev);
+
+	}
+
+	return NOTIFY_OK;
+}
+
+int of_platform_register_reconfig_notifier(void)
+{
+	platform_of_notifier.notifier_call = of_platform_notify;
+	return of_reconfig_notifier_register(&platform_of_notifier);
+}
+EXPORT_SYMBOL_GPL(of_platform_register_reconfig_notifier);
+
+#endif
+
 #endif /* CONFIG_OF_ADDRESS */
diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h
index c2b0627..01fe5d6 100644
--- a/include/linux/of_platform.h
+++ b/include/linux/of_platform.h
@@ -84,4 +84,14 @@ static inline int of_platform_populate(struct device_node *root,
 static inline void of_platform_depopulate(struct device *parent) { }
 #endif
 
+#ifdef CONFIG_OF_DYNAMIC
+extern int of_platform_register_reconfig_notifier(void);
+#else
+static inline int of_platform_register_reconfig_notifier(void)
+{
+	return 0;
+}
+#endif
+
+
 #endif	/* _LINUX_OF_PLATFORM_H */
-- 
1.7.12

Re: [PATCH v8 4/8] OF: platform: Add OF notifier handler

[Grant Likely]

On Tue, 28 Oct 2014 22:36:01 +0200
, Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
 wrote:
> Add OF notifier handler needed for creating/destroying platform devices
> according to dynamic runtime changes in the DT live tree.
> 
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>

Hi Pantelis,

Some comments below. Feel free to send me fixup patches instead of
respinning.

g.

> ---
>  drivers/base/platform.c     | 18 +++++++++--
>  drivers/of/platform.c       | 78 +++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/of_platform.h | 10 ++++++
>  3 files changed, 103 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index b2afc29..282bfec 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -1002,10 +1002,22 @@ int __init platform_bus_init(void)
>  
>  	error = device_register(&platform_bus);
>  	if (error)
> -		return error;
> -	error =  bus_register(&platform_bus_type);
> +		goto err_out;
> +
> +	error = bus_register(&platform_bus_type);
> +	if (error)
> +		goto err_unreg_dev;
> +
> +	error = of_platform_register_reconfig_notifier();
>  	if (error)
> -		device_unregister(&platform_bus);
> +		goto err_unreg_bus;

We really don't want to fail out here. If the notifier registration fails, it
doesn't make sense to cause the entire boot to fail.

Instead of refactoring the function, just add the call to
of_platform_register_reconfig_notifier(), and WARN_ON() failure without
bailing.

(Actually, you don't need to send me a fixup for this; I've gone ahead
and fixed it up in my tree)

> +
> +	return 0;
> +err_unreg_bus:
> +	bus_unregister(&platform_bus_type);
> +err_unreg_dev:
> +	device_unregister(&platform_bus);
> +err_out:
>  	return error;
>  }
>  
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 3b64d0b..aa8db92 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -546,4 +546,82 @@ void of_platform_depopulate(struct device *parent)
>  }
>  EXPORT_SYMBOL_GPL(of_platform_depopulate);
>  
> +#ifdef CONFIG_OF_DYNAMIC
> +
> +static struct notifier_block platform_of_notifier;
> +
> +static int of_platform_notify(struct notifier_block *nb,
> +				unsigned long action, void *arg)
> +{
> +	struct platform_device *pdev_parent, *pdev;
> +	struct device_node *dn;
> +	int state;
> +	bool children_left;
> +
> +	state = of_reconfig_get_state_change(action, arg);
> +
> +	/* no change? */
> +	if (state == -1)
> +		return NOTIFY_OK;
> +
> +	switch (action) {
> +	case OF_RECONFIG_ATTACH_NODE:
> +	case OF_RECONFIG_DETACH_NODE:
> +		dn = arg;
> +		break;
> +	case OF_RECONFIG_ADD_PROPERTY:
> +	case OF_RECONFIG_REMOVE_PROPERTY:
> +	case OF_RECONFIG_UPDATE_PROPERTY:
> +		dn = ((struct of_prop_reconfig *)arg)->dn;
> +		break;
> +	default:
> +		return NOTIFY_OK;
> +	}
> +
> +	if (state) {
> +
> +		/* verify that the parent is a bus */
> +		if (!of_match_node(of_default_bus_match_table, dn->parent))
> +			return NOTIFY_OK;	/* not for us */

This doesn't work reliably. Not all callers of of_platform_populate use
the of_default_bus_match_table. The code needs to actively track the
nodes that were used to create child devices. We've got a flag in the
device node now that you can use for that; OF_POPULATED_BUS.

> +
> +		/* pdev_parent may be NULL when no bus platform device */
> +		pdev_parent = of_find_device_by_node(dn->parent);
> +		pdev = of_platform_device_create(dn, NULL,
> +				pdev_parent ? &pdev_parent->dev : NULL);
> +		of_dev_put(pdev_parent);
> +
> +		if (pdev == NULL) {
> +			pr_err("%s: failed to create for '%s'\n",
> +					__func__, dn->full_name);
> +			/* of_platform_device_create tosses the error code */
> +			return notifier_from_errno(-EINVAL);
> +		}
> +
> +	} else {
> +
> +		/* find our device by node */
> +		pdev = of_find_device_by_node(dn);
> +		if (pdev == NULL)
> +			return NOTIFY_OK;	/* no? not meant for us */
> +
> +		/* unregister takes one ref away */
> +		of_platform_device_destroy(&pdev->dev, &children_left);
> +
> +		/* and put the reference of the find */
> +		of_dev_put(pdev);
> +
> +	}
> +
> +	return NOTIFY_OK;
> +}
> +
> +int of_platform_register_reconfig_notifier(void)
> +{
> +	platform_of_notifier.notifier_call = of_platform_notify;
> +	return of_reconfig_notifier_register(&platform_of_notifier);
> +}
> +EXPORT_SYMBOL_GPL(of_platform_register_reconfig_notifier);
> +
> +#endif
> +
>  #endif /* CONFIG_OF_ADDRESS */
> diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h
> index c2b0627..01fe5d6 100644
> --- a/include/linux/of_platform.h
> +++ b/include/linux/of_platform.h
> @@ -84,4 +84,14 @@ static inline int of_platform_populate(struct device_node *root,
>  static inline void of_platform_depopulate(struct device *parent) { }
>  #endif
>  
> +#ifdef CONFIG_OF_DYNAMIC
> +extern int of_platform_register_reconfig_notifier(void);
> +#else
> +static inline int of_platform_register_reconfig_notifier(void)
> +{
> +	return 0;
> +}
> +#endif
> +
> +
>  #endif	/* _LINUX_OF_PLATFORM_H */
> -- 
> 1.7.12
> 

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Re: [PATCH v8 4/8] OF: platform: Add OF notifier handler

[Pantelis Antoniou]

Hi Grant,

> On Nov 14, 2014, at 01:29 , Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> wrote:
> 
> On Tue, 28 Oct 2014 22:36:01 +0200
> , Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
> wrote:
>> Add OF notifier handler needed for creating/destroying platform devices
>> according to dynamic runtime changes in the DT live tree.
>> 
>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
> 
> Hi Pantelis,
> 
> Some comments below. Feel free to send me fixup patches instead of
> respinning.
> 

Sure, I’ll get around to send updated patches over the weekend.

> g.
> 
>> ---
>> drivers/base/platform.c     | 18 +++++++++--
>> drivers/of/platform.c       | 78 +++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/of_platform.h | 10 ++++++
>> 3 files changed, 103 insertions(+), 3 deletions(-)
>> 
>> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
>> index b2afc29..282bfec 100644
>> --- a/drivers/base/platform.c
>> +++ b/drivers/base/platform.c
>> @@ -1002,10 +1002,22 @@ int __init platform_bus_init(void)
>> 
>> 	error = device_register(&platform_bus);
>> 	if (error)
>> -		return error;
>> -	error =  bus_register(&platform_bus_type);
>> +		goto err_out;
>> +
>> +	error = bus_register(&platform_bus_type);
>> +	if (error)
>> +		goto err_unreg_dev;
>> +
>> +	error = of_platform_register_reconfig_notifier();
>> 	if (error)
>> -		device_unregister(&platform_bus);
>> +		goto err_unreg_bus;
> 
> We really don't want to fail out here. If the notifier registration fails, it
> doesn't make sense to cause the entire boot to fail.
> 
> Instead of refactoring the function, just add the call to
> of_platform_register_reconfig_notifier(), and WARN_ON() failure without
> bailing.
> 
> (Actually, you don't need to send me a fixup for this; I've gone ahead
> and fixed it up in my tree)
> 

I see. Thanks.

I’m curious under which condition the of_platform_register_reconfig_notifier()
would fail. Only under extreme low memory conditions (and very early in the
boot-sequence). I doubt we’ll get very far - the boot-sequence will croak shortly
after. 

>> +
>> +	return 0;
>> +err_unreg_bus:
>> +	bus_unregister(&platform_bus_type);
>> +err_unreg_dev:
>> +	device_unregister(&platform_bus);
>> +err_out:
>> 	return error;
>> }
>> 
>> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
>> index 3b64d0b..aa8db92 100644
>> --- a/drivers/of/platform.c
>> +++ b/drivers/of/platform.c
>> @@ -546,4 +546,82 @@ void of_platform_depopulate(struct device *parent)
>> }
>> EXPORT_SYMBOL_GPL(of_platform_depopulate);
>> 
>> +#ifdef CONFIG_OF_DYNAMIC
>> +
>> +static struct notifier_block platform_of_notifier;
>> +
>> +static int of_platform_notify(struct notifier_block *nb,
>> +				unsigned long action, void *arg)
>> +{
>> +	struct platform_device *pdev_parent, *pdev;
>> +	struct device_node *dn;
>> +	int state;
>> +	bool children_left;
>> +
>> +	state = of_reconfig_get_state_change(action, arg);
>> +
>> +	/* no change? */
>> +	if (state == -1)
>> +		return NOTIFY_OK;
>> +
>> +	switch (action) {
>> +	case OF_RECONFIG_ATTACH_NODE:
>> +	case OF_RECONFIG_DETACH_NODE:
>> +		dn = arg;
>> +		break;
>> +	case OF_RECONFIG_ADD_PROPERTY:
>> +	case OF_RECONFIG_REMOVE_PROPERTY:
>> +	case OF_RECONFIG_UPDATE_PROPERTY:
>> +		dn = ((struct of_prop_reconfig *)arg)->dn;
>> +		break;
>> +	default:
>> +		return NOTIFY_OK;
>> +	}
>> +
>> +	if (state) {
>> +
>> +		/* verify that the parent is a bus */
>> +		if (!of_match_node(of_default_bus_match_table, dn->parent))
>> +			return NOTIFY_OK;	/* not for us */
> 
> This doesn't work reliably. Not all callers of of_platform_populate use
> the of_default_bus_match_table. The code needs to actively track the
> nodes that were used to create child devices. We've got a flag in the
> device node now that you can use for that; OF_POPULATED_BUS.
> 

I see. That’s a relatively new flag no?

>> +
>> +		/* pdev_parent may be NULL when no bus platform device */
>> +		pdev_parent = of_find_device_by_node(dn->parent);
>> +		pdev = of_platform_device_create(dn, NULL,
>> +				pdev_parent ? &pdev_parent->dev : NULL);
>> +		of_dev_put(pdev_parent);
>> +
>> +		if (pdev == NULL) {
>> +			pr_err("%s: failed to create for '%s'\n",
>> +					__func__, dn->full_name);
>> +			/* of_platform_device_create tosses the error code */
>> +			return notifier_from_errno(-EINVAL);
>> +		}
>> +
>> +	} else {
>> +
>> +		/* find our device by node */
>> +		pdev = of_find_device_by_node(dn);
>> +		if (pdev == NULL)
>> +			return NOTIFY_OK;	/* no? not meant for us */
>> +
>> +		/* unregister takes one ref away */
>> +		of_platform_device_destroy(&pdev->dev, &children_left);
>> +
>> +		/* and put the reference of the find */
>> +		of_dev_put(pdev);
>> +
>> +	}
>> +
>> +	return NOTIFY_OK;
>> +}
>> +
>> +int of_platform_register_reconfig_notifier(void)
>> +{
>> +	platform_of_notifier.notifier_call = of_platform_notify;
>> +	return of_reconfig_notifier_register(&platform_of_notifier);
>> +}
>> +EXPORT_SYMBOL_GPL(of_platform_register_reconfig_notifier);
>> +
>> +#endif
>> +
>> #endif /* CONFIG_OF_ADDRESS */
>> diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h
>> index c2b0627..01fe5d6 100644
>> --- a/include/linux/of_platform.h
>> +++ b/include/linux/of_platform.h
>> @@ -84,4 +84,14 @@ static inline int of_platform_populate(struct device_node *root,
>> static inline void of_platform_depopulate(struct device *parent) { }
>> #endif
>> 
>> +#ifdef CONFIG_OF_DYNAMIC
>> +extern int of_platform_register_reconfig_notifier(void);
>> +#else
>> +static inline int of_platform_register_reconfig_notifier(void)
>> +{
>> +	return 0;
>> +}
>> +#endif
>> +
>> +
>> #endif	/* _LINUX_OF_PLATFORM_H */
>> -- 
>> 1.7.12

[PATCH v8 2/8] OF: selftest: Add overlay self-test support. (v2)

[Pantelis Antoniou]

This patch adds overlay tests to the OF selftest.

It tests overlay device addition/removal and whether
the apply revert sequence is correct.

Changes since V1:
* Added local fixups entries.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
---
 Documentation/devicetree/bindings/selftest.txt |  14 +
 drivers/of/selftest.c                          | 481 +++++++++++++++++++++++++
 drivers/of/testcase-data/testcases.dts         |  16 +
 drivers/of/testcase-data/tests-overlay.dtsi    | 180 +++++++++
 4 files changed, 691 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/selftest.txt
 create mode 100644 drivers/of/testcase-data/tests-overlay.dtsi

diff --git a/Documentation/devicetree/bindings/selftest.txt b/Documentation/devicetree/bindings/selftest.txt
new file mode 100644
index 0000000..0f92a22
--- /dev/null
+++ b/Documentation/devicetree/bindings/selftest.txt
@@ -0,0 +1,14 @@
+* OF selftest platform device
+
+** selftest
+
+Required properties:
+- compatible: must be "selftest"
+
+All other properties are optional.
+
+Example:
+	selftest {
+		compatible = "selftest";
+		status = "okay";
+	};
diff --git a/drivers/of/selftest.c b/drivers/of/selftest.c
index 16102fd..63aa0b2 100644
--- a/drivers/of/selftest.c
+++ b/drivers/of/selftest.c
@@ -17,6 +17,8 @@
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/of_platform.h>
 
 #include "of_private.h"
 
@@ -858,6 +860,484 @@ static void selftest_data_remove(void)
 	}
 }
 
+#ifdef CONFIG_OF_OVERLAY
+
+static int selftest_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+
+	if (np == NULL) {
+		dev_err(dev, "No OF data for device\n");
+		return -EINVAL;
+
+	}
+
+	dev_dbg(dev, "%s for node @%s\n", __func__, np->full_name);
+	return 0;
+}
+
+static int selftest_remove(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+
+	dev_dbg(dev, "%s for node @%s\n", __func__, np->full_name);
+	return 0;
+}
+
+static struct of_device_id selftest_match[] = {
+	{ .compatible = "selftest", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, altera_jtaguart_match);
+
+static struct platform_driver selftest_driver = {
+	.probe			= selftest_probe,
+	.remove			= selftest_remove,
+	.driver = {
+		.name		= "selftest",
+		.owner		= THIS_MODULE,
+		.of_match_table	= of_match_ptr(selftest_match),
+	},
+};
+
+/* get the platform device instantiated at the path */
+static struct platform_device *of_path_to_platform_device(const char *path)
+{
+	struct device_node *np;
+	struct platform_device *pdev;
+
+	np = of_find_node_by_path(path);
+	if (np == NULL)
+		return NULL;
+
+	pdev = of_find_device_by_node(np);
+	of_node_put(np);
+
+	return pdev;
+}
+
+/* find out if a platform device exists at that path */
+static int of_path_platform_device_exists(const char *path)
+{
+	struct platform_device *pdev;
+
+	pdev = of_path_to_platform_device(path);
+	platform_device_put(pdev);
+	return pdev != NULL;
+}
+
+static const char *selftest_path(int nr)
+{
+	static char buf[256];
+
+	snprintf(buf, sizeof(buf) - 1,
+		"/testcase-data/overlay-node/test-bus/test-selftest%d", nr);
+	buf[sizeof(buf) - 1] = '\0';
+
+	return buf;
+}
+
+static const char *overlay_path(int nr)
+{
+	static char buf[256];
+
+	snprintf(buf, sizeof(buf) - 1,
+		"/testcase-data/overlay%d", nr);
+	buf[sizeof(buf) - 1] = '\0';
+
+	return buf;
+}
+
+static const char *bus_path = "/testcase-data/overlay-node/test-bus";
+
+static int of_selftest_apply_overlay(int selftest_nr, int overlay_nr,
+		int *overlay_id)
+{
+	struct device_node *np = NULL;
+	int ret, id = -1;
+
+	np = of_find_node_by_path(overlay_path(overlay_nr));
+	if (np == NULL) {
+		selftest(0, "could not find overlay node @\"%s\"\n",
+				overlay_path(overlay_nr));
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = of_overlay_create(np);
+	if (ret < 0) {
+		selftest(0, "could not create overlay from \"%s\"\n",
+				overlay_path(overlay_nr));
+		goto out;
+	}
+	id = ret;
+
+	ret = 0;
+
+out:
+	of_node_put(np);
+
+	if (overlay_id)
+		*overlay_id = id;
+
+	return ret;
+}
+
+/* apply an overlay while checking before and after states */
+static int of_selftest_apply_overlay_check(int overlay_nr, int selftest_nr,
+		int before, int after)
+{
+	int ret;
+
+	/* selftest device must not be in before state */
+	if (of_path_platform_device_exists(selftest_path(selftest_nr))
+			!= before) {
+		selftest(0, "overlay @\"%s\" with device @\"%s\" %s\n",
+				overlay_path(overlay_nr),
+				selftest_path(selftest_nr),
+				!before ? "enabled" : "disabled");
+		return -EINVAL;
+	}
+
+	ret = of_selftest_apply_overlay(overlay_nr, selftest_nr, NULL);
+	if (ret != 0) {
+		/* of_selftest_apply_overlay already called selftest() */
+		return ret;
+	}
+
+	/* selftest device must be to set to after state */
+	if (of_path_platform_device_exists(selftest_path(selftest_nr))
+			!= after) {
+		selftest(0, "overlay @\"%s\" failed to create @\"%s\" %s\n",
+				overlay_path(overlay_nr),
+				selftest_path(selftest_nr),
+				!after ? "enabled" : "disabled");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* apply an overlay and then revert it while checking before, after states */
+static int of_selftest_apply_revert_overlay_check(int overlay_nr,
+		int selftest_nr, int before, int after)
+{
+	int ret, ov_id;
+
+	/* selftest device must be in before state */
+	if (of_path_platform_device_exists(selftest_path(selftest_nr))
+			!= before) {
+		selftest(0, "overlay @\"%s\" with device @\"%s\" %s\n",
+				overlay_path(overlay_nr),
+				selftest_path(selftest_nr),
+				!before ? "enabled" : "disabled");
+		return -EINVAL;
+	}
+
+	/* apply the overlay */
+	ret = of_selftest_apply_overlay(overlay_nr, selftest_nr, &ov_id);
+	if (ret != 0) {
+		/* of_selftest_apply_overlay already called selftest() */
+		return ret;
+	}
+
+	/* selftest device must be in after state */
+	if (of_path_platform_device_exists(selftest_path(selftest_nr))
+			!= after) {
+		selftest(0, "overlay @\"%s\" failed to create @\"%s\" %s\n",
+				overlay_path(overlay_nr),
+				selftest_path(selftest_nr),
+				!after ? "enabled" : "disabled");
+		return -EINVAL;
+	}
+
+	ret = of_overlay_destroy(ov_id);
+	if (ret != 0) {
+		selftest(0, "overlay @\"%s\" failed to be destroyed @\"%s\"\n",
+				overlay_path(overlay_nr),
+				selftest_path(selftest_nr));
+		return ret;
+	}
+
+	/* selftest device must be again in before state */
+	if (of_path_platform_device_exists(selftest_path(selftest_nr))
+			!= before) {
+		selftest(0, "overlay @\"%s\" with device @\"%s\" %s\n",
+				overlay_path(overlay_nr),
+				selftest_path(selftest_nr),
+				!before ? "enabled" : "disabled");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* test activation of device */
+static void of_selftest_overlay_0(void)
+{
+	int ret;
+
+	/* device should enable */
+	ret = of_selftest_apply_overlay_check(0, 0, 0, 1);
+	if (ret != 0)
+		return;
+
+	selftest(1, "overlay test %d passed\n", 0);
+}
+
+/* test deactivation of device */
+static void of_selftest_overlay_1(void)
+{
+	int ret;
+
+	/* device should disable */
+	ret = of_selftest_apply_overlay_check(1, 1, 1, 0);
+	if (ret != 0)
+		return;
+
+	selftest(1, "overlay test %d passed\n", 1);
+}
+
+/* test activation of device */
+static void of_selftest_overlay_2(void)
+{
+	int ret;
+
+	/* device should enable */
+	ret = of_selftest_apply_overlay_check(2, 2, 0, 1);
+	if (ret != 0)
+		return;
+
+	selftest(1, "overlay test %d passed\n", 2);
+}
+
+/* test deactivation of device */
+static void of_selftest_overlay_3(void)
+{
+	int ret;
+
+	/* device should disable */
+	ret = of_selftest_apply_overlay_check(3, 3, 1, 0);
+	if (ret != 0)
+		return;
+
+	selftest(1, "overlay test %d passed\n", 3);
+}
+
+/* test activation of a full device node */
+static void of_selftest_overlay_4(void)
+{
+	int ret;
+
+	/* device should disable */
+	ret = of_selftest_apply_overlay_check(4, 4, 0, 1);
+	if (ret != 0)
+		return;
+
+	selftest(1, "overlay test %d passed\n", 4);
+}
+
+/* test overlay apply/revert sequence */
+static void of_selftest_overlay_5(void)
+{
+	int ret;
+
+	/* device should disable */
+	ret = of_selftest_apply_revert_overlay_check(5, 5, 0, 1);
+	if (ret != 0)
+		return;
+
+	selftest(1, "overlay test %d passed\n", 5);
+}
+
+/* test overlay application in sequence */
+static void of_selftest_overlay_6(void)
+{
+	struct device_node *np;
+	int ret, i, ov_id[2];
+	int overlay_nr = 6, selftest_nr = 6;
+	int before = 0, after = 1;
+
+	/* selftest device must be in before state */
+	for (i = 0; i < 2; i++) {
+		if (of_path_platform_device_exists(
+					selftest_path(selftest_nr + i))
+				!= before) {
+			selftest(0, "overlay @\"%s\" with device @\"%s\" %s\n",
+					overlay_path(overlay_nr + i),
+					selftest_path(selftest_nr + i),
+					!before ? "enabled" : "disabled");
+			return;
+		}
+	}
+
+	/* apply the overlays */
+	for (i = 0; i < 2; i++) {
+
+		np = of_find_node_by_path(overlay_path(overlay_nr + i));
+		if (np == NULL) {
+			selftest(0, "could not find overlay node @\"%s\"\n",
+					overlay_path(overlay_nr + i));
+			return;
+		}
+
+		ret = of_overlay_create(np);
+		if (ret < 0)  {
+			selftest(0, "could not create overlay from \"%s\"\n",
+					overlay_path(overlay_nr + i));
+			return;
+		}
+		ov_id[i] = ret;
+	}
+
+	for (i = 0; i < 2; i++) {
+		/* selftest device must be in after state */
+		if (of_path_platform_device_exists(
+					selftest_path(selftest_nr + i))
+				!= after) {
+			selftest(0, "overlay @\"%s\" failed @\"%s\" %s\n",
+					overlay_path(overlay_nr + i),
+					selftest_path(selftest_nr + i),
+					!after ? "enabled" : "disabled");
+			return;
+		}
+	}
+
+	for (i = 1; i >= 0; i--) {
+		ret = of_overlay_destroy(ov_id[i]);
+		if (ret != 0) {
+			selftest(0, "overlay @\"%s\" failed destroy @\"%s\"\n",
+					overlay_path(overlay_nr + i),
+					selftest_path(selftest_nr + i));
+			return;
+		}
+	}
+
+	for (i = 0; i < 2; i++) {
+		/* selftest device must be again in before state */
+		if (of_path_platform_device_exists(
+					selftest_path(selftest_nr + i))
+				!= before) {
+			selftest(0, "overlay @\"%s\" with device @\"%s\" %s\n",
+					overlay_path(overlay_nr + i),
+					selftest_path(selftest_nr + i),
+					!before ? "enabled" : "disabled");
+			return;
+		}
+	}
+
+	selftest(1, "overlay test %d passed\n", 6);
+}
+
+/* test overlay application in sequence */
+static void of_selftest_overlay_8(void)
+{
+	struct device_node *np;
+	int ret, i, ov_id[2];
+	int overlay_nr = 8, selftest_nr = 8;
+
+	/* we don't care about device state in this test */
+
+	/* apply the overlays */
+	for (i = 0; i < 2; i++) {
+
+		np = of_find_node_by_path(overlay_path(overlay_nr + i));
+		if (np == NULL) {
+			selftest(0, "could not find overlay node @\"%s\"\n",
+					overlay_path(overlay_nr + i));
+			return;
+		}
+
+		ret = of_overlay_create(np);
+		if (ret < 0)  {
+			selftest(0, "could not create overlay from \"%s\"\n",
+					overlay_path(overlay_nr + i));
+			return;
+		}
+		ov_id[i] = ret;
+	}
+
+	/* now try to remove first overlay (it should fail) */
+	ret = of_overlay_destroy(ov_id[0]);
+	if (ret == 0) {
+		selftest(0, "overlay @\"%s\" was destroyed @\"%s\"\n",
+				overlay_path(overlay_nr + 0),
+				selftest_path(selftest_nr));
+		return;
+	}
+
+	/* removing them in order should work */
+	for (i = 1; i >= 0; i--) {
+		ret = of_overlay_destroy(ov_id[i]);
+		if (ret != 0) {
+			selftest(0, "overlay @\"%s\" not destroyed @\"%s\"\n",
+					overlay_path(overlay_nr + i),
+					selftest_path(selftest_nr));
+			return;
+		}
+	}
+
+	selftest(1, "overlay test %d passed\n", 8);
+}
+
+static void __init of_selftest_overlay(void)
+{
+	struct device_node *bus_np = NULL;
+	int ret;
+
+	ret = platform_driver_register(&selftest_driver);
+	if (ret != 0) {
+		selftest(0, "could not register selftest driver\n");
+		goto out;
+	}
+
+	bus_np = of_find_node_by_path(bus_path);
+	if (bus_np == NULL) {
+		selftest(0, "could not find bus_path \"%s\"\n", bus_path);
+		goto out;
+	}
+
+	ret = of_platform_populate(bus_np, of_default_bus_match_table,
+			NULL, NULL);
+	if (ret != 0) {
+		selftest(0, "could not populate bus @ \"%s\"\n", bus_path);
+		goto out;
+	}
+
+	if (!of_path_platform_device_exists(selftest_path(100))) {
+		selftest(0, "could not find selftest0 @ \"%s\"\n",
+				selftest_path(100));
+		goto out;
+	}
+
+	if (of_path_platform_device_exists(selftest_path(101))) {
+		selftest(0, "selftest1 @ \"%s\" should not exist\n",
+				selftest_path(101));
+		goto out;
+	}
+
+	selftest(1, "basic infrastructure of overlays passed");
+
+	/* tests in sequence */
+	of_selftest_overlay_0();
+	of_selftest_overlay_1();
+	of_selftest_overlay_2();
+	of_selftest_overlay_3();
+	of_selftest_overlay_4();
+	of_selftest_overlay_5();
+	of_selftest_overlay_6();
+	of_selftest_overlay_8();
+
+out:
+	of_node_put(bus_np);
+}
+
+#else
+static inline void __init of_selftest_overlay(void) { }
+#endif
+
 static int __init of_selftest(void)
 {
 	struct device_node *np;
@@ -888,6 +1368,7 @@ static int __init of_selftest(void)
 	of_selftest_parse_interrupts_extended();
 	of_selftest_match_node();
 	of_selftest_platform_populate();
+	of_selftest_overlay();
 
 	/* removing selftest data from live tree */
 	selftest_data_remove();
diff --git a/drivers/of/testcase-data/testcases.dts b/drivers/of/testcase-data/testcases.dts
index b6bc41b..12f7c3d 100644
--- a/drivers/of/testcase-data/testcases.dts
+++ b/drivers/of/testcase-data/testcases.dts
@@ -13,6 +13,7 @@
 #include "tests-interrupts.dtsi"
 #include "tests-match.dtsi"
 #include "tests-platform.dtsi"
+#include "tests-overlay.dtsi"
 
 /*
  * phandle fixup data - generated by dtc patches that aren't upstream.
@@ -59,5 +60,20 @@
 		testcase-device2 {
 			interrupt-parent = <0x00000000>;
 		};
+		overlay2 {
+			fragment@0 {
+				target = <0x00000000>;
+			};
+		};
+		overlay3 {
+			fragment@0 {
+				target = <0x00000000>;
+			};
+		};
+		overlay4 {
+			fragment@0 {
+				target = <0x00000000>;
+			};
+		};
 	};
 }; };
diff --git a/drivers/of/testcase-data/tests-overlay.dtsi b/drivers/of/testcase-data/tests-overlay.dtsi
new file mode 100644
index 0000000..75976da
--- /dev/null
+++ b/drivers/of/testcase-data/tests-overlay.dtsi
@@ -0,0 +1,180 @@
+
+/ {
+	testcase-data {
+		overlay-node {
+
+			/* test bus */
+			selftestbus: test-bus {
+				compatible = "simple-bus";
+				#address-cells = <1>;
+				#size-cells = <0>;
+
+				selftest100: test-selftest100 {
+					compatible = "selftest";
+					status = "okay";
+					reg = <100>;
+				};
+
+				selftest101: test-selftest101 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <101>;
+				};
+
+				selftest0: test-selftest0 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <0>;
+				};
+
+				selftest1: test-selftest1 {
+					compatible = "selftest";
+					status = "okay";
+					reg = <1>;
+				};
+
+				selftest2: test-selftest2 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <2>;
+				};
+
+				selftest3: test-selftest3 {
+					compatible = "selftest";
+					status = "okay";
+					reg = <3>;
+				};
+
+				selftest5: test-selftest5 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <5>;
+				};
+
+				selftest6: test-selftest6 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <6>;
+				};
+
+				selftest7: test-selftest7 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <7>;
+				};
+
+				selftest8: test-selftest8 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <8>;
+				};
+			};
+		};
+
+		/* test enable using absolute target path */
+		overlay0 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest0";
+				__overlay__ {
+					status = "okay";
+				};
+			};
+		};
+
+		/* test disable using absolute target path */
+		overlay1 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest1";
+				__overlay__ {
+					status = "disabled";
+				};
+			};
+		};
+
+		/* test enable using label */
+		overlay2 {
+			fragment@0 {
+				target = <&selftest2>;
+				__overlay__ {
+					status = "okay";
+				};
+			};
+		};
+
+		/* test disable using label */
+		overlay3 {
+			fragment@0 {
+				target = <&selftest3>;
+				__overlay__ {
+					status = "disabled";
+				};
+			};
+		};
+
+		/* test insertion of a full node */
+		overlay4 {
+			fragment@0 {
+				target = <&selftestbus>;
+				__overlay__ {
+
+					/* suppress DTC warning */
+					#address-cells = <1>;
+					#size-cells = <0>;
+
+					test-selftest4 {
+						compatible = "selftest";
+						status = "okay";
+						reg = <4>;
+					};
+				};
+			};
+		};
+
+		/* test overlay apply revert */
+		overlay5 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest5";
+				__overlay__ {
+					status = "okay";
+				};
+			};
+		};
+
+		/* test overlays application and removal in sequence */
+		overlay6 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest6";
+				__overlay__ {
+					status = "okay";
+				};
+			};
+		};
+		overlay7 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest7";
+				__overlay__ {
+					status = "okay";
+				};
+			};
+		};
+
+		/* test overlays application and removal in bad sequence */
+		overlay8 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest8";
+				__overlay__ {
+					status = "okay";
+				};
+			};
+		};
+		overlay9 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest8";
+				__overlay__ {
+					property-foo = "bar";
+				};
+			};
+		};
+
+	};
+};
-- 
1.7.12

[PATCH v8 3/8] OF: DT-Overlay configfs interface (v2)

[Pantelis Antoniou]

Add a runtime interface to using configfs for generic device tree overlay
usage.

A device-tree configfs entry is created in /config/device-tree/overlays

* To create an overlay you mkdir the directory:

	# mkdir /config/device-tree/overlays/foo

* Either you echo the overlay firmware file to the path property file.

	# echo foo.dtbo >/config/device-tree/overlays/foo/path

* Or you cat the contents of the overlay to the dtbo file

	# cat foo.dtbo >/config/device-tree/overlays/foo/dtbo

The overlay file will be applied.

To remove it simply rmdir the directory.

	# rmdir /config/device-tree/overlays/foo

Changes since v1:
* of_resolve() -> of_resolve_phandles().

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
---
 drivers/of/Kconfig    |   7 ++
 drivers/of/Makefile   |   1 +
 drivers/of/configfs.c | 340 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 348 insertions(+)
 create mode 100644 drivers/of/configfs.c

diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index aa315c4..d59ba40 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -90,4 +90,11 @@ config OF_OVERLAY
 	select OF_DEVICE
 	select OF_RESOLVE
 
+config OF_CONFIGFS
+	bool "OpenFirmware Overlay ConfigFS interface"
+	select CONFIGFS_FS
+	select OF_OVERLAY
+	help
+	  Enable a simple user-space driver DT overlay interface.
+
 endmenu # OF
diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index 1bfe462..6d12949 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_OF_MTD)	+= of_mtd.o
 obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
 obj-$(CONFIG_OF_RESOLVE)  += resolver.o
 obj-$(CONFIG_OF_OVERLAY) += overlay.o
+obj-$(CONFIG_OF_CONFIGFS) += configfs.o
 
 CFLAGS_fdt.o = -I$(src)/../../scripts/dtc/libfdt
 CFLAGS_fdt_address.o = -I$(src)/../../scripts/dtc/libfdt
diff --git a/drivers/of/configfs.c b/drivers/of/configfs.c
new file mode 100644
index 0000000..932f572
--- /dev/null
+++ b/drivers/of/configfs.c
@@ -0,0 +1,340 @@
+/*
+ * Configfs entries for device-tree
+ *
+ * Copyright (C) 2013 - Pantelis Antoniou <panto@antoniou-consulting.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#include <linux/ctype.h>
+#include <linux/cpu.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/proc_fs.h>
+#include <linux/configfs.h>
+#include <linux/types.h>
+#include <linux/stat.h>
+#include <linux/limits.h>
+#include <linux/file.h>
+#include <linux/vmalloc.h>
+#include <linux/firmware.h>
+
+#include "of_private.h"
+
+#ifdef CONFIG_OF_OVERLAY
+
+struct cfs_overlay_item {
+	struct config_item	item;
+
+	char			path[PATH_MAX];
+
+	const struct firmware	*fw;
+	struct device_node	*overlay;
+	int			ov_id;
+
+	void			*dtbo;
+	int			dtbo_size;
+};
+
+static int create_overlay(struct cfs_overlay_item *overlay, void *blob)
+{
+	int err;
+
+	/* unflatten the tree */
+	of_fdt_unflatten_tree((void *)blob, &overlay->overlay);
+	if (overlay->overlay == NULL) {
+		pr_err("%s: failed to unflatten tree\n", __func__);
+		err = -EINVAL;
+		goto out_err;
+	}
+	pr_debug("%s: unflattened OK\n", __func__);
+
+	/* mark it as detached */
+	of_node_set_flag(overlay->overlay, OF_DETACHED);
+
+	/* perform resolution */
+	err = of_resolve_phandles(overlay->overlay);
+	if (err != 0) {
+		pr_err("%s: Failed to resolve tree\n", __func__);
+		goto out_err;
+	}
+	pr_debug("%s: resolved OK\n", __func__);
+
+	err = of_overlay_create(overlay->overlay);
+	if (err < 0) {
+		pr_err("%s: Failed to create overlay (err=%d)\n",
+				__func__, err);
+		goto out_err;
+	}
+	overlay->ov_id = err;
+
+out_err:
+	return err;
+}
+
+static inline struct cfs_overlay_item *to_cfs_overlay_item(
+		struct config_item *item)
+{
+	return item ? container_of(item, struct cfs_overlay_item, item) : NULL;
+}
+
+CONFIGFS_ATTR_STRUCT(cfs_overlay_item);
+#define CFS_OVERLAY_ITEM_ATTR(_name, _mode, _show, _store)	\
+struct cfs_overlay_item_attribute cfs_overlay_item_attr_##_name = \
+	__CONFIGFS_ATTR(_name, _mode, _show, _store)
+#define CFS_OVERLAY_ITEM_ATTR_RO(_name, _show)	\
+struct cfs_overlay_item_attribute cfs_overlay_item_attr_##_name = \
+	__CONFIGFS_ATTR_RO(_name, _show)
+
+CONFIGFS_BIN_ATTR_STRUCT(cfs_overlay_item);
+#define CFS_OVERLAY_ITEM_BIN_ATTR(_name, _mode, _read, _write, _priv, _max) \
+struct cfs_overlay_item_bin_attribute cfs_overlay_item_bin_attr_##_name = \
+	__CONFIGFS_BIN_ATTR(_name, _mode, _read, _write, _priv, _max)
+#define CFS_OVERLAY_ITEM_BIN_ATTR_RO(_name, _read, _priv, _max)	\
+struct cfs_overlay_item_bin_attribute cfs_overlay_item_bin_attr_##_name = \
+	__CONFIGFS_BIN_ATTR_RO(_name, _read, _priv, _max)
+
+static ssize_t cfs_overlay_item_path_show(struct cfs_overlay_item *overlay,
+		char *page)
+{
+	return sprintf(page, "%s\n", overlay->path);
+}
+
+static ssize_t cfs_overlay_item_path_store(struct cfs_overlay_item *overlay,
+		const char *page, size_t count)
+{
+	const char *p = page;
+	char *s;
+	int err;
+
+	/* if it's set do not allow changes */
+	if (overlay->path[0] != '\0' || overlay->dtbo_size > 0)
+		return -EPERM;
+
+	/* copy to path buffer (and make sure it's always zero terminated */
+	count = snprintf(overlay->path, sizeof(overlay->path) - 1, "%s", p);
+	overlay->path[sizeof(overlay->path) - 1] = '\0';
+
+	/* strip trailing newlines */
+	s = overlay->path + strlen(overlay->path);
+	while (s > overlay->path && *--s == '\n')
+		*s = '\0';
+
+	pr_debug("%s: path is '%s'\n", __func__, overlay->path);
+
+	err = request_firmware(&overlay->fw, overlay->path, NULL);
+	if (err != 0)
+		goto out_err;
+
+	err = create_overlay(overlay, (void *)overlay->fw->data);
+	if (err != 0)
+		goto out_err;
+
+	return count;
+
+out_err:
+
+	release_firmware(overlay->fw);
+	overlay->fw = NULL;
+
+	overlay->path[0] = '\0';
+	return err;
+}
+
+static ssize_t cfs_overlay_item_status_show(struct cfs_overlay_item *overlay,
+		char *page)
+{
+	return sprintf(page, "%s\n",
+			overlay->ov_id >= 0 ? "applied" : "unapplied");
+}
+
+CFS_OVERLAY_ITEM_ATTR(path, S_IRUGO | S_IWUSR,
+		cfs_overlay_item_path_show, cfs_overlay_item_path_store);
+CFS_OVERLAY_ITEM_ATTR_RO(status, cfs_overlay_item_status_show);
+
+static struct configfs_attribute *cfs_overlay_attrs[] = {
+	&cfs_overlay_item_attr_path.attr,
+	&cfs_overlay_item_attr_status.attr,
+	NULL,
+};
+
+ssize_t cfs_overlay_item_dtbo_read(struct cfs_overlay_item *overlay,
+		void *buf, size_t max_count)
+{
+	pr_debug("%s: buf=%p max_count=%u\n", __func__,
+			buf, max_count);
+
+	if (overlay->dtbo == NULL)
+		return 0;
+
+	/* copy if buffer provided */
+	if (buf != NULL) {
+		/* the buffer must be large enough */
+		if (overlay->dtbo_size > max_count)
+			return -ENOSPC;
+
+		memcpy(buf, overlay->dtbo, overlay->dtbo_size);
+	}
+
+	return overlay->dtbo_size;
+}
+
+ssize_t cfs_overlay_item_dtbo_write(struct cfs_overlay_item *overlay,
+		const void *buf, size_t count)
+{
+	int err;
+
+	/* if it's set do not allow changes */
+	if (overlay->path[0] != '\0' || overlay->dtbo_size > 0)
+		return -EPERM;
+
+	/* copy the contents */
+	overlay->dtbo = kmemdup(buf, count, GFP_KERNEL);
+	if (overlay->dtbo == NULL)
+		return -ENOMEM;
+
+	overlay->dtbo_size = count;
+
+	err = create_overlay(overlay, overlay->dtbo);
+	if (err != 0)
+		goto out_err;
+
+	return count;
+
+out_err:
+	kfree(overlay->dtbo);
+	overlay->dtbo = NULL;
+	overlay->dtbo_size = 0;
+
+	return err;
+}
+
+CFS_OVERLAY_ITEM_BIN_ATTR(dtbo, S_IRUGO | S_IWUSR,
+		cfs_overlay_item_dtbo_read, cfs_overlay_item_dtbo_write,
+		NULL, SZ_1M);
+
+static struct configfs_bin_attribute *cfs_overlay_bin_attrs[] = {
+	&cfs_overlay_item_bin_attr_dtbo.bin_attr,
+	NULL,
+};
+
+static void cfs_overlay_release(struct config_item *item)
+{
+	struct cfs_overlay_item *overlay = to_cfs_overlay_item(item);
+
+	if (overlay->ov_id >= 0)
+		of_overlay_destroy(overlay->ov_id);
+	if (overlay->fw)
+		release_firmware(overlay->fw);
+	/* kfree with NULL is safe */
+	kfree(overlay->dtbo);
+	kfree(overlay);
+}
+
+CONFIGFS_ATTR_OPS(cfs_overlay_item);
+CONFIGFS_BIN_ATTR_OPS(cfs_overlay_item);
+static struct configfs_item_operations cfs_overlay_item_ops = {
+	.release		= cfs_overlay_release,
+	.show_attribute		= cfs_overlay_item_attr_show,
+	.store_attribute	= cfs_overlay_item_attr_store,
+	.read_bin_attribute	= cfs_overlay_item_bin_attr_read,
+	.write_bin_attribute	= cfs_overlay_item_bin_attr_write,
+};
+
+static struct config_item_type cfs_overlay_type = {
+	.ct_item_ops	= &cfs_overlay_item_ops,
+	.ct_attrs	= cfs_overlay_attrs,
+	.ct_bin_attrs	= cfs_overlay_bin_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_item *cfs_overlay_group_make_item(
+		struct config_group *group, const char *name)
+{
+	struct cfs_overlay_item *overlay;
+
+	overlay = kzalloc(sizeof(*overlay), GFP_KERNEL);
+	if (!overlay)
+		return ERR_PTR(-ENOMEM);
+	overlay->ov_id = -1;
+
+	config_item_init_type_name(&overlay->item, name, &cfs_overlay_type);
+	return &overlay->item;
+}
+
+static void cfs_overlay_group_drop_item(struct config_group *group,
+		struct config_item *item)
+{
+	struct cfs_overlay_item *overlay = to_cfs_overlay_item(item);
+
+	config_item_put(&overlay->item);
+}
+
+static struct configfs_group_operations overlays_ops = {
+	.make_item	= cfs_overlay_group_make_item,
+	.drop_item	= cfs_overlay_group_drop_item,
+};
+
+static struct config_item_type overlays_type = {
+	.ct_group_ops   = &overlays_ops,
+	.ct_owner       = THIS_MODULE,
+};
+
+#endif /* CONFIG_OF_OVERLAY */
+
+static struct configfs_group_operations of_cfs_ops = {
+	/* empty - we don't allow anything to be created */
+};
+
+static struct config_item_type of_cfs_type = {
+	.ct_group_ops   = &of_cfs_ops,
+	.ct_owner       = THIS_MODULE,
+};
+
+struct config_group of_cfs_overlay_group;
+
+struct config_group *of_cfs_def_groups[] = {
+#ifdef CONFIG_OF_OVERLAY
+	&of_cfs_overlay_group,
+#endif
+	NULL
+};
+
+static struct configfs_subsystem of_cfs_subsys = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf = "device-tree",
+			.ci_type = &of_cfs_type,
+		},
+		.default_groups = of_cfs_def_groups,
+	},
+	.su_mutex = __MUTEX_INITIALIZER(of_cfs_subsys.su_mutex),
+};
+
+static int __init of_cfs_init(void)
+{
+	int ret;
+
+	pr_info("%s\n", __func__);
+
+	config_group_init(&of_cfs_subsys.su_group);
+#ifdef CONFIG_OF_OVERLAY
+	config_group_init_type_name(&of_cfs_overlay_group, "overlays",
+			&overlays_type);
+#endif
+
+	ret = configfs_register_subsystem(&of_cfs_subsys);
+	if (ret != 0) {
+		pr_err("%s: failed to register subsys\n", __func__);
+		goto out;
+	}
+	pr_info("%s: OK\n", __func__);
+out:
+	return ret;
+}
+late_initcall(of_cfs_init);
-- 
1.7.12

Re: [PATCH v8 3/8] OF: DT-Overlay configfs interface (v2)

[Grant Likely]

Hi Pantelis,

Comments below...

On Tue, 28 Oct 2014 22:36:00 +0200
, Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
 wrote:
> Add a runtime interface to using configfs for generic device tree overlay
> usage.
> 
> A device-tree configfs entry is created in /config/device-tree/overlays
> 
> * To create an overlay you mkdir the directory:
> 
> 	# mkdir /config/device-tree/overlays/foo
> 
> * Either you echo the overlay firmware file to the path property file.
> 
> 	# echo foo.dtbo >/config/device-tree/overlays/foo/path
> 
> * Or you cat the contents of the overlay to the dtbo file
> 
> 	# cat foo.dtbo >/config/device-tree/overlays/foo/dtbo
> 
> The overlay file will be applied.
> 
> To remove it simply rmdir the directory.
> 
> 	# rmdir /config/device-tree/overlays/foo

The above is documentation on how to use it, but it isn't a good commit
message. The above should be moved into a documentation file (if it
isn't already and I've missed it) and the commit message should give
detail about what was needed, what was changed to make it happen, and
what the result of the new code is.

> 
> Changes since v1:
> * of_resolve() -> of_resolve_phandles().
> 
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
> ---
>  drivers/of/Kconfig    |   7 ++
>  drivers/of/Makefile   |   1 +
>  drivers/of/configfs.c | 340 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 348 insertions(+)
>  create mode 100644 drivers/of/configfs.c
> 
> diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
> index aa315c4..d59ba40 100644
> --- a/drivers/of/Kconfig
> +++ b/drivers/of/Kconfig
> @@ -90,4 +90,11 @@ config OF_OVERLAY
>  	select OF_DEVICE
>  	select OF_RESOLVE
>  
> +config OF_CONFIGFS
> +	bool "OpenFirmware Overlay ConfigFS interface"

Despite all the APIs being prefixed with OpenFirmware, this isn't an
OpenFirmware interface, it is a device tree interface.

> +	select CONFIGFS_FS
> +	select OF_OVERLAY
> +	help
> +	  Enable a simple user-space driver DT overlay interface.
> +
>  endmenu # OF
> diff --git a/drivers/of/Makefile b/drivers/of/Makefile
> index 1bfe462..6d12949 100644
> --- a/drivers/of/Makefile
> +++ b/drivers/of/Makefile
> @@ -15,6 +15,7 @@ obj-$(CONFIG_OF_MTD)	+= of_mtd.o
>  obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
>  obj-$(CONFIG_OF_RESOLVE)  += resolver.o
>  obj-$(CONFIG_OF_OVERLAY) += overlay.o
> +obj-$(CONFIG_OF_CONFIGFS) += configfs.o

Tip: Insert lines in the middle of the block, roughly alphabetically
sorted. It cuts down on merge conflicts that way.

>  
>  CFLAGS_fdt.o = -I$(src)/../../scripts/dtc/libfdt
>  CFLAGS_fdt_address.o = -I$(src)/../../scripts/dtc/libfdt
> diff --git a/drivers/of/configfs.c b/drivers/of/configfs.c
> new file mode 100644
> index 0000000..932f572
> --- /dev/null
> +++ b/drivers/of/configfs.c
> @@ -0,0 +1,340 @@
> +/*
> + * Configfs entries for device-tree
> + *
> + * Copyright (C) 2013 - Pantelis Antoniou <panto-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +#include <linux/ctype.h>
> +#include <linux/cpu.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_fdt.h>
> +#include <linux/spinlock.h>
> +#include <linux/slab.h>
> +#include <linux/proc_fs.h>
> +#include <linux/configfs.h>
> +#include <linux/types.h>
> +#include <linux/stat.h>
> +#include <linux/limits.h>
> +#include <linux/file.h>
> +#include <linux/vmalloc.h>
> +#include <linux/firmware.h>
> +
> +#include "of_private.h"
> +
> +#ifdef CONFIG_OF_OVERLAY

???

This file shouldn't even be compiled if CONFIG_OF_OVERLAY isn't
selected. Why is this here?

> +
> +struct cfs_overlay_item {
> +	struct config_item	item;
> +
> +	char			path[PATH_MAX];
> +
> +	const struct firmware	*fw;
> +	struct device_node	*overlay;
> +	int			ov_id;
> +
> +	void			*dtbo;
> +	int			dtbo_size;
> +};
> +
> +static int create_overlay(struct cfs_overlay_item *overlay, void *blob)
> +{
> +	int err;
> +
> +	/* unflatten the tree */
> +	of_fdt_unflatten_tree((void *)blob, &overlay->overlay);

blob is already void*

> +	if (overlay->overlay == NULL) {
> +		pr_err("%s: failed to unflatten tree\n", __func__);
> +		err = -EINVAL;
> +		goto out_err;
> +	}
> +	pr_debug("%s: unflattened OK\n", __func__);
> +
> +	/* mark it as detached */
> +	of_node_set_flag(overlay->overlay, OF_DETACHED);
> +
> +	/* perform resolution */
> +	err = of_resolve_phandles(overlay->overlay);
> +	if (err != 0) {
> +		pr_err("%s: Failed to resolve tree\n", __func__);
> +		goto out_err;
> +	}
> +	pr_debug("%s: resolved OK\n", __func__);
> +
> +	err = of_overlay_create(overlay->overlay);
> +	if (err < 0) {
> +		pr_err("%s: Failed to create overlay (err=%d)\n",
> +				__func__, err);
> +		goto out_err;
> +	}
> +	overlay->ov_id = err;
> +
> +out_err:
> +	return err;
> +}
> +
> +static inline struct cfs_overlay_item *to_cfs_overlay_item(
> +		struct config_item *item)
> +{
> +	return item ? container_of(item, struct cfs_overlay_item, item) : NULL;
> +}
> +
> +CONFIGFS_ATTR_STRUCT(cfs_overlay_item);
> +#define CFS_OVERLAY_ITEM_ATTR(_name, _mode, _show, _store)	\
> +struct cfs_overlay_item_attribute cfs_overlay_item_attr_##_name = \
> +	__CONFIGFS_ATTR(_name, _mode, _show, _store)
> +#define CFS_OVERLAY_ITEM_ATTR_RO(_name, _show)	\
> +struct cfs_overlay_item_attribute cfs_overlay_item_attr_##_name = \
> +	__CONFIGFS_ATTR_RO(_name, _show)
> +
> +CONFIGFS_BIN_ATTR_STRUCT(cfs_overlay_item);
> +#define CFS_OVERLAY_ITEM_BIN_ATTR(_name, _mode, _read, _write, _priv, _max) \
> +struct cfs_overlay_item_bin_attribute cfs_overlay_item_bin_attr_##_name = \
> +	__CONFIGFS_BIN_ATTR(_name, _mode, _read, _write, _priv, _max)
> +#define CFS_OVERLAY_ITEM_BIN_ATTR_RO(_name, _read, _priv, _max)	\
> +struct cfs_overlay_item_bin_attribute cfs_overlay_item_bin_attr_##_name = \
> +	__CONFIGFS_BIN_ATTR_RO(_name, _read, _priv, _max)
> +
> +static ssize_t cfs_overlay_item_path_show(struct cfs_overlay_item *overlay,
> +		char *page)
> +{
> +	return sprintf(page, "%s\n", overlay->path);
> +}
> +
> +static ssize_t cfs_overlay_item_path_store(struct cfs_overlay_item *overlay,
> +		const char *page, size_t count)
> +{
> +	const char *p = page;
> +	char *s;
> +	int err;
> +
> +	/* if it's set do not allow changes */
> +	if (overlay->path[0] != '\0' || overlay->dtbo_size > 0)
> +		return -EPERM;
> +
> +	/* copy to path buffer (and make sure it's always zero terminated */
> +	count = snprintf(overlay->path, sizeof(overlay->path) - 1, "%s", p);
> +	overlay->path[sizeof(overlay->path) - 1] = '\0';
> +
> +	/* strip trailing newlines */
> +	s = overlay->path + strlen(overlay->path);
> +	while (s > overlay->path && *--s == '\n')
> +		*s = '\0';
> +
> +	pr_debug("%s: path is '%s'\n", __func__, overlay->path);
> +
> +	err = request_firmware(&overlay->fw, overlay->path, NULL);
> +	if (err != 0)
> +		goto out_err;
> +
> +	err = create_overlay(overlay, (void *)overlay->fw->data);
> +	if (err != 0)
> +		goto out_err;
> +
> +	return count;
> +
> +out_err:
> +
> +	release_firmware(overlay->fw);
> +	overlay->fw = NULL;
> +
> +	overlay->path[0] = '\0';
> +	return err;
> +}
> +
> +static ssize_t cfs_overlay_item_status_show(struct cfs_overlay_item *overlay,
> +		char *page)
> +{
> +	return sprintf(page, "%s\n",
> +			overlay->ov_id >= 0 ? "applied" : "unapplied");
> +}
> +
> +CFS_OVERLAY_ITEM_ATTR(path, S_IRUGO | S_IWUSR,
> +		cfs_overlay_item_path_show, cfs_overlay_item_path_store);

World writable? Am I reading this correctly?

DT modifications are privileged. A user can potentially get arbitrary
access to i2c, spi, gpio or other things that shouldn't be allowed. This
feature give access right into the Linux driver model.

Before this can be merged, it needs to be locked down, and there needs
to be documentation about how it is locked down. Owned by root is only
the first step, there also needs to be some rules about which nodes can
be modified by the configfs interface. By default think no modifications
should be allowed on a tree unless there are properties somewhere in the
tree that explicitly allow modifications to be performed.

Regardless, there needs to be a proposal made about the security model
so that it can be discussed and analyzed by folks better versed in
security that either of us. I would like to get Kees Cook to take a look
at what we are doing here.

> +CFS_OVERLAY_ITEM_ATTR_RO(status, cfs_overlay_item_status_show);
> +
> +static struct configfs_attribute *cfs_overlay_attrs[] = {
> +	&cfs_overlay_item_attr_path.attr,
> +	&cfs_overlay_item_attr_status.attr,
> +	NULL,
> +};
> +
> +ssize_t cfs_overlay_item_dtbo_read(struct cfs_overlay_item *overlay,
> +		void *buf, size_t max_count)
> +{
> +	pr_debug("%s: buf=%p max_count=%u\n", __func__,
> +			buf, max_count);
> +
> +	if (overlay->dtbo == NULL)
> +		return 0;
> +
> +	/* copy if buffer provided */
> +	if (buf != NULL) {
> +		/* the buffer must be large enough */
> +		if (overlay->dtbo_size > max_count)
> +			return -ENOSPC;
> +
> +		memcpy(buf, overlay->dtbo, overlay->dtbo_size);
> +	}
> +
> +	return overlay->dtbo_size;
> +}
> +
> +ssize_t cfs_overlay_item_dtbo_write(struct cfs_overlay_item *overlay,
> +		const void *buf, size_t count)
> +{
> +	int err;
> +
> +	/* if it's set do not allow changes */
> +	if (overlay->path[0] != '\0' || overlay->dtbo_size > 0)
> +		return -EPERM;
> +
> +	/* copy the contents */
> +	overlay->dtbo = kmemdup(buf, count, GFP_KERNEL);
> +	if (overlay->dtbo == NULL)
> +		return -ENOMEM;
> +
> +	overlay->dtbo_size = count;
> +
> +	err = create_overlay(overlay, overlay->dtbo);
> +	if (err != 0)
> +		goto out_err;
> +
> +	return count;
> +
> +out_err:
> +	kfree(overlay->dtbo);
> +	overlay->dtbo = NULL;
> +	overlay->dtbo_size = 0;
> +
> +	return err;
> +}
> +
> +CFS_OVERLAY_ITEM_BIN_ATTR(dtbo, S_IRUGO | S_IWUSR,
> +		cfs_overlay_item_dtbo_read, cfs_overlay_item_dtbo_write,
> +		NULL, SZ_1M);
> +
> +static struct configfs_bin_attribute *cfs_overlay_bin_attrs[] = {
> +	&cfs_overlay_item_bin_attr_dtbo.bin_attr,
> +	NULL,
> +};
> +
> +static void cfs_overlay_release(struct config_item *item)
> +{
> +	struct cfs_overlay_item *overlay = to_cfs_overlay_item(item);
> +
> +	if (overlay->ov_id >= 0)
> +		of_overlay_destroy(overlay->ov_id);
> +	if (overlay->fw)
> +		release_firmware(overlay->fw);
> +	/* kfree with NULL is safe */
> +	kfree(overlay->dtbo);
> +	kfree(overlay);
> +}
> +
> +CONFIGFS_ATTR_OPS(cfs_overlay_item);
> +CONFIGFS_BIN_ATTR_OPS(cfs_overlay_item);
> +static struct configfs_item_operations cfs_overlay_item_ops = {
> +	.release		= cfs_overlay_release,
> +	.show_attribute		= cfs_overlay_item_attr_show,
> +	.store_attribute	= cfs_overlay_item_attr_store,
> +	.read_bin_attribute	= cfs_overlay_item_bin_attr_read,
> +	.write_bin_attribute	= cfs_overlay_item_bin_attr_write,
> +};
> +
> +static struct config_item_type cfs_overlay_type = {
> +	.ct_item_ops	= &cfs_overlay_item_ops,
> +	.ct_attrs	= cfs_overlay_attrs,
> +	.ct_bin_attrs	= cfs_overlay_bin_attrs,
> +	.ct_owner	= THIS_MODULE,
> +};
> +
> +static struct config_item *cfs_overlay_group_make_item(
> +		struct config_group *group, const char *name)
> +{
> +	struct cfs_overlay_item *overlay;
> +
> +	overlay = kzalloc(sizeof(*overlay), GFP_KERNEL);
> +	if (!overlay)
> +		return ERR_PTR(-ENOMEM);
> +	overlay->ov_id = -1;
> +
> +	config_item_init_type_name(&overlay->item, name, &cfs_overlay_type);
> +	return &overlay->item;
> +}
> +
> +static void cfs_overlay_group_drop_item(struct config_group *group,
> +		struct config_item *item)
> +{
> +	struct cfs_overlay_item *overlay = to_cfs_overlay_item(item);
> +
> +	config_item_put(&overlay->item);
> +}
> +
> +static struct configfs_group_operations overlays_ops = {
> +	.make_item	= cfs_overlay_group_make_item,
> +	.drop_item	= cfs_overlay_group_drop_item,
> +};
> +
> +static struct config_item_type overlays_type = {
> +	.ct_group_ops   = &overlays_ops,
> +	.ct_owner       = THIS_MODULE,
> +};
> +
> +#endif /* CONFIG_OF_OVERLAY */
> +
> +static struct configfs_group_operations of_cfs_ops = {
> +	/* empty - we don't allow anything to be created */
> +};
> +
> +static struct config_item_type of_cfs_type = {
> +	.ct_group_ops   = &of_cfs_ops,
> +	.ct_owner       = THIS_MODULE,
> +};
> +
> +struct config_group of_cfs_overlay_group;
> +
> +struct config_group *of_cfs_def_groups[] = {
> +#ifdef CONFIG_OF_OVERLAY
> +	&of_cfs_overlay_group,
> +#endif
> +	NULL
> +};
> +
> +static struct configfs_subsystem of_cfs_subsys = {
> +	.su_group = {
> +		.cg_item = {
> +			.ci_namebuf = "device-tree",
> +			.ci_type = &of_cfs_type,
> +		},
> +		.default_groups = of_cfs_def_groups,
> +	},
> +	.su_mutex = __MUTEX_INITIALIZER(of_cfs_subsys.su_mutex),
> +};
> +
> +static int __init of_cfs_init(void)
> +{
> +	int ret;
> +
> +	pr_info("%s\n", __func__);
> +
> +	config_group_init(&of_cfs_subsys.su_group);
> +#ifdef CONFIG_OF_OVERLAY
> +	config_group_init_type_name(&of_cfs_overlay_group, "overlays",
> +			&overlays_type);
> +#endif
> +
> +	ret = configfs_register_subsystem(&of_cfs_subsys);
> +	if (ret != 0) {
> +		pr_err("%s: failed to register subsys\n", __func__);
> +		goto out;
> +	}
> +	pr_info("%s: OK\n", __func__);
> +out:
> +	return ret;
> +}
> +late_initcall(of_cfs_init);
> -- 
> 1.7.12
> 

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Re: [PATCH v8 3/8] OF: DT-Overlay configfs interface (v2)

[Pantelis Antoniou]

Hi Grant,

> On Nov 25, 2014, at 12:28 , Grant Likely <grant.likely@secretlab.ca> wrote:
> 
> Hi Pantelis,
> 
> Comments below...
> 
> On Tue, 28 Oct 2014 22:36:00 +0200
> , Pantelis Antoniou <pantelis.antoniou@konsulko.com>
> wrote:
>> Add a runtime interface to using configfs for generic device tree overlay
>> usage.
>> 
>> A device-tree configfs entry is created in /config/device-tree/overlays
>> 
>> * To create an overlay you mkdir the directory:
>> 
>> 	# mkdir /config/device-tree/overlays/foo
>> 
>> * Either you echo the overlay firmware file to the path property file.
>> 
>> 	# echo foo.dtbo >/config/device-tree/overlays/foo/path
>> 
>> * Or you cat the contents of the overlay to the dtbo file
>> 
>> 	# cat foo.dtbo >/config/device-tree/overlays/foo/dtbo
>> 
>> The overlay file will be applied.
>> 
>> To remove it simply rmdir the directory.
>> 
>> 	# rmdir /config/device-tree/overlays/foo
> 
> The above is documentation on how to use it, but it isn't a good commit
> message. The above should be moved into a documentation file (if it
> isn't already and I've missed it) and the commit message should give
> detail about what was needed, what was changed to make it happen, and
> what the result of the new code is.
> 

Hmm, okie dokie.

>> 
>> Changes since v1:
>> * of_resolve() -> of_resolve_phandles().
>> 
>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>> ---
>> drivers/of/Kconfig    |   7 ++
>> drivers/of/Makefile   |   1 +
>> drivers/of/configfs.c | 340 ++++++++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 348 insertions(+)
>> create mode 100644 drivers/of/configfs.c
>> 
>> diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
>> index aa315c4..d59ba40 100644
>> --- a/drivers/of/Kconfig
>> +++ b/drivers/of/Kconfig
>> @@ -90,4 +90,11 @@ config OF_OVERLAY
>> 	select OF_DEVICE
>> 	select OF_RESOLVE
>> 
>> +config OF_CONFIGFS
>> +	bool "OpenFirmware Overlay ConfigFS interface"
> 
> Despite all the APIs being prefixed with OpenFirmware, this isn't an
> OpenFirmware interface, it is a device tree interface.
> 

OK, so device tree config fs interface?

>> +	select CONFIGFS_FS
>> +	select OF_OVERLAY
>> +	help
>> +	  Enable a simple user-space driver DT overlay interface.
>> +
>> endmenu # OF
>> diff --git a/drivers/of/Makefile b/drivers/of/Makefile
>> index 1bfe462..6d12949 100644
>> --- a/drivers/of/Makefile
>> +++ b/drivers/of/Makefile
>> @@ -15,6 +15,7 @@ obj-$(CONFIG_OF_MTD)	+= of_mtd.o
>> obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
>> obj-$(CONFIG_OF_RESOLVE)  += resolver.o
>> obj-$(CONFIG_OF_OVERLAY) += overlay.o
>> +obj-$(CONFIG_OF_CONFIGFS) += configfs.o
> 
> Tip: Insert lines in the middle of the block, roughly alphabetically
> sorted. It cuts down on merge conflicts that way.
> 

k

>> 
>> CFLAGS_fdt.o = -I$(src)/../../scripts/dtc/libfdt
>> CFLAGS_fdt_address.o = -I$(src)/../../scripts/dtc/libfdt
>> diff --git a/drivers/of/configfs.c b/drivers/of/configfs.c
>> new file mode 100644
>> index 0000000..932f572
>> --- /dev/null
>> +++ b/drivers/of/configfs.c
>> @@ -0,0 +1,340 @@
>> +/*
>> + * Configfs entries for device-tree
>> + *
>> + * Copyright (C) 2013 - Pantelis Antoniou <panto@antoniou-consulting.com>
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License
>> + * as published by the Free Software Foundation; either version
>> + * 2 of the License, or (at your option) any later version.
>> + */
>> +#include <linux/ctype.h>
>> +#include <linux/cpu.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_fdt.h>
>> +#include <linux/spinlock.h>
>> +#include <linux/slab.h>
>> +#include <linux/proc_fs.h>
>> +#include <linux/configfs.h>
>> +#include <linux/types.h>
>> +#include <linux/stat.h>
>> +#include <linux/limits.h>
>> +#include <linux/file.h>
>> +#include <linux/vmalloc.h>
>> +#include <linux/firmware.h>
>> +
>> +#include "of_private.h"
>> +
>> +#ifdef CONFIG_OF_OVERLAY
> 
> ???
> 
> This file shouldn't even be compiled if CONFIG_OF_OVERLAY isn't
> selected. Why is this here?
> 

Err, good question.

>> +
>> +struct cfs_overlay_item {
>> +	struct config_item	item;
>> +
>> +	char			path[PATH_MAX];
>> +
>> +	const struct firmware	*fw;
>> +	struct device_node	*overlay;
>> +	int			ov_id;
>> +
>> +	void			*dtbo;
>> +	int			dtbo_size;
>> +};
>> +
>> +static int create_overlay(struct cfs_overlay_item *overlay, void *blob)
>> +{
>> +	int err;
>> +
>> +	/* unflatten the tree */
>> +	of_fdt_unflatten_tree((void *)blob, &overlay->overlay);
> 
> blob is already void*
> 

ok

>> +	if (overlay->overlay == NULL) {
>> +		pr_err("%s: failed to unflatten tree\n", __func__);
>> +		err = -EINVAL;
>> +		goto out_err;
>> +	}
>> +	pr_debug("%s: unflattened OK\n", __func__);
>> +
>> +	/* mark it as detached */
>> +	of_node_set_flag(overlay->overlay, OF_DETACHED);
>> +
>> +	/* perform resolution */
>> +	err = of_resolve_phandles(overlay->overlay);
>> +	if (err != 0) {
>> +		pr_err("%s: Failed to resolve tree\n", __func__);
>> +		goto out_err;
>> +	}
>> +	pr_debug("%s: resolved OK\n", __func__);
>> +
>> +	err = of_overlay_create(overlay->overlay);
>> +	if (err < 0) {
>> +		pr_err("%s: Failed to create overlay (err=%d)\n",
>> +				__func__, err);
>> +		goto out_err;
>> +	}
>> +	overlay->ov_id = err;
>> +
>> +out_err:
>> +	return err;
>> +}
>> +
>> +static inline struct cfs_overlay_item *to_cfs_overlay_item(
>> +		struct config_item *item)
>> +{
>> +	return item ? container_of(item, struct cfs_overlay_item, item) : NULL;
>> +}
>> +
>> +CONFIGFS_ATTR_STRUCT(cfs_overlay_item);
>> +#define CFS_OVERLAY_ITEM_ATTR(_name, _mode, _show, _store)	\
>> +struct cfs_overlay_item_attribute cfs_overlay_item_attr_##_name = \
>> +	__CONFIGFS_ATTR(_name, _mode, _show, _store)
>> +#define CFS_OVERLAY_ITEM_ATTR_RO(_name, _show)	\
>> +struct cfs_overlay_item_attribute cfs_overlay_item_attr_##_name = \
>> +	__CONFIGFS_ATTR_RO(_name, _show)
>> +
>> +CONFIGFS_BIN_ATTR_STRUCT(cfs_overlay_item);
>> +#define CFS_OVERLAY_ITEM_BIN_ATTR(_name, _mode, _read, _write, _priv, _max) \
>> +struct cfs_overlay_item_bin_attribute cfs_overlay_item_bin_attr_##_name = \
>> +	__CONFIGFS_BIN_ATTR(_name, _mode, _read, _write, _priv, _max)
>> +#define CFS_OVERLAY_ITEM_BIN_ATTR_RO(_name, _read, _priv, _max)	\
>> +struct cfs_overlay_item_bin_attribute cfs_overlay_item_bin_attr_##_name = \
>> +	__CONFIGFS_BIN_ATTR_RO(_name, _read, _priv, _max)
>> +
>> +static ssize_t cfs_overlay_item_path_show(struct cfs_overlay_item *overlay,
>> +		char *page)
>> +{
>> +	return sprintf(page, "%s\n", overlay->path);
>> +}
>> +
>> +static ssize_t cfs_overlay_item_path_store(struct cfs_overlay_item *overlay,
>> +		const char *page, size_t count)
>> +{
>> +	const char *p = page;
>> +	char *s;
>> +	int err;
>> +
>> +	/* if it's set do not allow changes */
>> +	if (overlay->path[0] != '\0' || overlay->dtbo_size > 0)
>> +		return -EPERM;
>> +
>> +	/* copy to path buffer (and make sure it's always zero terminated */
>> +	count = snprintf(overlay->path, sizeof(overlay->path) - 1, "%s", p);
>> +	overlay->path[sizeof(overlay->path) - 1] = '\0';
>> +
>> +	/* strip trailing newlines */
>> +	s = overlay->path + strlen(overlay->path);
>> +	while (s > overlay->path && *--s == '\n')
>> +		*s = '\0';
>> +
>> +	pr_debug("%s: path is '%s'\n", __func__, overlay->path);
>> +
>> +	err = request_firmware(&overlay->fw, overlay->path, NULL);
>> +	if (err != 0)
>> +		goto out_err;
>> +
>> +	err = create_overlay(overlay, (void *)overlay->fw->data);
>> +	if (err != 0)
>> +		goto out_err;
>> +
>> +	return count;
>> +
>> +out_err:
>> +
>> +	release_firmware(overlay->fw);
>> +	overlay->fw = NULL;
>> +
>> +	overlay->path[0] = '\0';
>> +	return err;
>> +}
>> +
>> +static ssize_t cfs_overlay_item_status_show(struct cfs_overlay_item *overlay,
>> +		char *page)
>> +{
>> +	return sprintf(page, "%s\n",
>> +			overlay->ov_id >= 0 ? "applied" : "unapplied");
>> +}
>> +
>> +CFS_OVERLAY_ITEM_ATTR(path, S_IRUGO | S_IWUSR,
>> +		cfs_overlay_item_path_show, cfs_overlay_item_path_store);
> 
> World writable? Am I reading this correctly?
> 

Err, user writeable, world readable. “-rw-r--r—"

> DT modifications are privileged. A user can potentially get arbitrary
> access to i2c, spi, gpio or other things that shouldn't be allowed. This
> feature give access right into the Linux driver model.
> 

Yes, it does.

> Before this can be merged, it needs to be locked down, and there needs
> to be documentation about how it is locked down. Owned by root is only
> the first step, there also needs to be some rules about which nodes can
> be modified by the configfs interface. By default think no modifications
> should be allowed on a tree unless there are properties somewhere in the
> tree that explicitly allow modifications to be performed.
> 

TBH this is more of a debug level interface. The way I see it a different
overlay manager, that’s tuned to the platform, should handle the overlay
request and application, in a manner that’s not directly open to user
control. For example in a beaglebone you’d have a ‘cape’ manager reading
the i2c eeproms and request the overlays they match without any user-space
implication.

However, this is an interface that developers will use daily, so I agree
that we need to look into the security model now before it’s too late.

How do you feel for something like this in chosen:

overlay-targets = “/ocp”, “/pinctrl”;

That would allow overlays to target the ocp and pinctrl nodes (and all their
children). To allow overlays to attach everywhere just use

overlay-targets = “/“;

> Regardless, there needs to be a proposal made about the security model
> so that it can be discussed and analyzed by folks better versed in
> security that either of us. I would like to get Kees Cook to take a look
> at what we are doing here.
> 

Admittedly we could use some help here.
 
>> +CFS_OVERLAY_ITEM_ATTR_RO(status, cfs_overlay_item_status_show);
>> +
>> +static struct configfs_attribute *cfs_overlay_attrs[] = {
>> +	&cfs_overlay_item_attr_path.attr,
>> +	&cfs_overlay_item_attr_status.attr,
>> +	NULL,
>> +};
>> +
>> +ssize_t cfs_overlay_item_dtbo_read(struct cfs_overlay_item *overlay,
>> +		void *buf, size_t max_count)
>> +{
>> +	pr_debug("%s: buf=%p max_count=%u\n", __func__,
>> +			buf, max_count);
>> +
>> +	if (overlay->dtbo == NULL)
>> +		return 0;
>> +
>> +	/* copy if buffer provided */
>> +	if (buf != NULL) {
>> +		/* the buffer must be large enough */
>> +		if (overlay->dtbo_size > max_count)
>> +			return -ENOSPC;
>> +
>> +		memcpy(buf, overlay->dtbo, overlay->dtbo_size);
>> +	}
>> +
>> +	return overlay->dtbo_size;
>> +}
>> +
>> +ssize_t cfs_overlay_item_dtbo_write(struct cfs_overlay_item *overlay,
>> +		const void *buf, size_t count)
>> +{
>> +	int err;
>> +
>> +	/* if it's set do not allow changes */
>> +	if (overlay->path[0] != '\0' || overlay->dtbo_size > 0)
>> +		return -EPERM;
>> +
>> +	/* copy the contents */
>> +	overlay->dtbo = kmemdup(buf, count, GFP_KERNEL);
>> +	if (overlay->dtbo == NULL)
>> +		return -ENOMEM;
>> +
>> +	overlay->dtbo_size = count;
>> +
>> +	err = create_overlay(overlay, overlay->dtbo);
>> +	if (err != 0)
>> +		goto out_err;
>> +
>> +	return count;
>> +
>> +out_err:
>> +	kfree(overlay->dtbo);
>> +	overlay->dtbo = NULL;
>> +	overlay->dtbo_size = 0;
>> +
>> +	return err;
>> +}
>> +
>> +CFS_OVERLAY_ITEM_BIN_ATTR(dtbo, S_IRUGO | S_IWUSR,
>> +		cfs_overlay_item_dtbo_read, cfs_overlay_item_dtbo_write,
>> +		NULL, SZ_1M);
>> +
>> +static struct configfs_bin_attribute *cfs_overlay_bin_attrs[] = {
>> +	&cfs_overlay_item_bin_attr_dtbo.bin_attr,
>> +	NULL,
>> +};
>> +
>> +static void cfs_overlay_release(struct config_item *item)
>> +{
>> +	struct cfs_overlay_item *overlay = to_cfs_overlay_item(item);
>> +
>> +	if (overlay->ov_id >= 0)
>> +		of_overlay_destroy(overlay->ov_id);
>> +	if (overlay->fw)
>> +		release_firmware(overlay->fw);
>> +	/* kfree with NULL is safe */
>> +	kfree(overlay->dtbo);
>> +	kfree(overlay);
>> +}
>> +
>> +CONFIGFS_ATTR_OPS(cfs_overlay_item);
>> +CONFIGFS_BIN_ATTR_OPS(cfs_overlay_item);
>> +static struct configfs_item_operations cfs_overlay_item_ops = {
>> +	.release		= cfs_overlay_release,
>> +	.show_attribute		= cfs_overlay_item_attr_show,
>> +	.store_attribute	= cfs_overlay_item_attr_store,
>> +	.read_bin_attribute	= cfs_overlay_item_bin_attr_read,
>> +	.write_bin_attribute	= cfs_overlay_item_bin_attr_write,
>> +};
>> +
>> +static struct config_item_type cfs_overlay_type = {
>> +	.ct_item_ops	= &cfs_overlay_item_ops,
>> +	.ct_attrs	= cfs_overlay_attrs,
>> +	.ct_bin_attrs	= cfs_overlay_bin_attrs,
>> +	.ct_owner	= THIS_MODULE,
>> +};
>> +
>> +static struct config_item *cfs_overlay_group_make_item(
>> +		struct config_group *group, const char *name)
>> +{
>> +	struct cfs_overlay_item *overlay;
>> +
>> +	overlay = kzalloc(sizeof(*overlay), GFP_KERNEL);
>> +	if (!overlay)
>> +		return ERR_PTR(-ENOMEM);
>> +	overlay->ov_id = -1;
>> +
>> +	config_item_init_type_name(&overlay->item, name, &cfs_overlay_type);
>> +	return &overlay->item;
>> +}
>> +
>> +static void cfs_overlay_group_drop_item(struct config_group *group,
>> +		struct config_item *item)
>> +{
>> +	struct cfs_overlay_item *overlay = to_cfs_overlay_item(item);
>> +
>> +	config_item_put(&overlay->item);
>> +}
>> +
>> +static struct configfs_group_operations overlays_ops = {
>> +	.make_item	= cfs_overlay_group_make_item,
>> +	.drop_item	= cfs_overlay_group_drop_item,
>> +};
>> +
>> +static struct config_item_type overlays_type = {
>> +	.ct_group_ops   = &overlays_ops,
>> +	.ct_owner       = THIS_MODULE,
>> +};
>> +
>> +#endif /* CONFIG_OF_OVERLAY */
>> +
>> +static struct configfs_group_operations of_cfs_ops = {
>> +	/* empty - we don't allow anything to be created */
>> +};
>> +
>> +static struct config_item_type of_cfs_type = {
>> +	.ct_group_ops   = &of_cfs_ops,
>> +	.ct_owner       = THIS_MODULE,
>> +};
>> +
>> +struct config_group of_cfs_overlay_group;
>> +
>> +struct config_group *of_cfs_def_groups[] = {
>> +#ifdef CONFIG_OF_OVERLAY
>> +	&of_cfs_overlay_group,
>> +#endif
>> +	NULL
>> +};
>> +
>> +static struct configfs_subsystem of_cfs_subsys = {
>> +	.su_group = {
>> +		.cg_item = {
>> +			.ci_namebuf = "device-tree",
>> +			.ci_type = &of_cfs_type,
>> +		},
>> +		.default_groups = of_cfs_def_groups,
>> +	},
>> +	.su_mutex = __MUTEX_INITIALIZER(of_cfs_subsys.su_mutex),
>> +};
>> +
>> +static int __init of_cfs_init(void)
>> +{
>> +	int ret;
>> +
>> +	pr_info("%s\n", __func__);
>> +
>> +	config_group_init(&of_cfs_subsys.su_group);
>> +#ifdef CONFIG_OF_OVERLAY
>> +	config_group_init_type_name(&of_cfs_overlay_group, "overlays",
>> +			&overlays_type);
>> +#endif
>> +
>> +	ret = configfs_register_subsystem(&of_cfs_subsys);
>> +	if (ret != 0) {
>> +		pr_err("%s: failed to register subsys\n", __func__);
>> +		goto out;
>> +	}
>> +	pr_info("%s: OK\n", __func__);
>> +out:
>> +	return ret;
>> +}
>> +late_initcall(of_cfs_init);
>> -- 
>> 1.7.12
>> 

Regards

— Pantelis

Re: [PATCH v8 3/8] OF: DT-Overlay configfs interface (v2)

[Grant Likely]

On Tue, 25 Nov 2014 16:50:15 +0200
, Pantelis Antoniou <panto-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
 wrote:
> Hi Grant,
> 
> > On Nov 25, 2014, at 12:28 , Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> wrote:
> > 
> > Hi Pantelis,
> > 
> > Comments below...
> > 
> > On Tue, 28 Oct 2014 22:36:00 +0200
> > , Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
> > wrote:
> >> Add a runtime interface to using configfs for generic device tree overlay
> >> usage.
> >> 
> >> A device-tree configfs entry is created in /config/device-tree/overlays
> >> 
> >> * To create an overlay you mkdir the directory:
> >> 
> >> 	# mkdir /config/device-tree/overlays/foo
> >> 
> >> * Either you echo the overlay firmware file to the path property file.
> >> 
> >> 	# echo foo.dtbo >/config/device-tree/overlays/foo/path
> >> 
> >> * Or you cat the contents of the overlay to the dtbo file
> >> 
> >> 	# cat foo.dtbo >/config/device-tree/overlays/foo/dtbo
> >> 
> >> The overlay file will be applied.
> >> 
> >> To remove it simply rmdir the directory.
> >> 
> >> 	# rmdir /config/device-tree/overlays/foo
> > 
> > The above is documentation on how to use it, but it isn't a good commit
> > message. The above should be moved into a documentation file (if it
> > isn't already and I've missed it) and the commit message should give
> > detail about what was needed, what was changed to make it happen, and
> > what the result of the new code is.
> > 
> 
> Hmm, okie dokie.
> 
> >> 
> >> Changes since v1:
> >> * of_resolve() -> of_resolve_phandles().
> >> 
> >> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
> >> ---
> >> drivers/of/Kconfig    |   7 ++
> >> drivers/of/Makefile   |   1 +
> >> drivers/of/configfs.c | 340 ++++++++++++++++++++++++++++++++++++++++++++++++++
> >> 3 files changed, 348 insertions(+)
> >> create mode 100644 drivers/of/configfs.c
> >> 
> >> diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
> >> index aa315c4..d59ba40 100644
> >> --- a/drivers/of/Kconfig
> >> +++ b/drivers/of/Kconfig
> >> @@ -90,4 +90,11 @@ config OF_OVERLAY
> >> 	select OF_DEVICE
> >> 	select OF_RESOLVE
> >> 
> >> +config OF_CONFIGFS
> >> +	bool "OpenFirmware Overlay ConfigFS interface"
> > 
> > Despite all the APIs being prefixed with OpenFirmware, this isn't an
> > OpenFirmware interface, it is a device tree interface.
> > 
> 
> OK, so device tree config fs interface?

Yes

> 
> >> +	select CONFIGFS_FS
> >> +	select OF_OVERLAY
> >> +	help
> >> +	  Enable a simple user-space driver DT overlay interface.
> >> +
> >> endmenu # OF
> >> diff --git a/drivers/of/Makefile b/drivers/of/Makefile
> >> index 1bfe462..6d12949 100644
> >> --- a/drivers/of/Makefile
> >> +++ b/drivers/of/Makefile
> >> @@ -15,6 +15,7 @@ obj-$(CONFIG_OF_MTD)	+= of_mtd.o
> >> obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
> >> obj-$(CONFIG_OF_RESOLVE)  += resolver.o
> >> obj-$(CONFIG_OF_OVERLAY) += overlay.o
> >> +obj-$(CONFIG_OF_CONFIGFS) += configfs.o
> > 
> > Tip: Insert lines in the middle of the block, roughly alphabetically
> > sorted. It cuts down on merge conflicts that way.
> > 
> 
> k
> 
> >> 
> >> CFLAGS_fdt.o = -I$(src)/../../scripts/dtc/libfdt
> >> CFLAGS_fdt_address.o = -I$(src)/../../scripts/dtc/libfdt
> >> diff --git a/drivers/of/configfs.c b/drivers/of/configfs.c
> >> new file mode 100644
> >> index 0000000..932f572
> >> --- /dev/null
> >> +++ b/drivers/of/configfs.c
> >> @@ -0,0 +1,340 @@
> >> +/*
> >> + * Configfs entries for device-tree
> >> + *
> >> + * Copyright (C) 2013 - Pantelis Antoniou <panto@antoniou-consulting.com>
> >> + *
> >> + * This program is free software; you can redistribute it and/or
> >> + * modify it under the terms of the GNU General Public License
> >> + * as published by the Free Software Foundation; either version
> >> + * 2 of the License, or (at your option) any later version.
> >> + */
> >> +#include <linux/ctype.h>
> >> +#include <linux/cpu.h>
> >> +#include <linux/module.h>
> >> +#include <linux/of.h>
> >> +#include <linux/of_fdt.h>
> >> +#include <linux/spinlock.h>
> >> +#include <linux/slab.h>
> >> +#include <linux/proc_fs.h>
> >> +#include <linux/configfs.h>
> >> +#include <linux/types.h>
> >> +#include <linux/stat.h>
> >> +#include <linux/limits.h>
> >> +#include <linux/file.h>
> >> +#include <linux/vmalloc.h>
> >> +#include <linux/firmware.h>
> >> +
> >> +#include "of_private.h"
> >> +
> >> +#ifdef CONFIG_OF_OVERLAY
> > 
> > ???
> > 
> > This file shouldn't even be compiled if CONFIG_OF_OVERLAY isn't
> > selected. Why is this here?
> > 
> 
> Err, good question.
> 
> >> +
> >> +struct cfs_overlay_item {
> >> +	struct config_item	item;
> >> +
> >> +	char			path[PATH_MAX];
> >> +
> >> +	const struct firmware	*fw;
> >> +	struct device_node	*overlay;
> >> +	int			ov_id;
> >> +
> >> +	void			*dtbo;
> >> +	int			dtbo_size;
> >> +};
> >> +
> >> +static int create_overlay(struct cfs_overlay_item *overlay, void *blob)
> >> +{
> >> +	int err;
> >> +
> >> +	/* unflatten the tree */
> >> +	of_fdt_unflatten_tree((void *)blob, &overlay->overlay);
> > 
> > blob is already void*
> > 
> 
> ok
> 
> >> +	if (overlay->overlay == NULL) {
> >> +		pr_err("%s: failed to unflatten tree\n", __func__);
> >> +		err = -EINVAL;
> >> +		goto out_err;
> >> +	}
> >> +	pr_debug("%s: unflattened OK\n", __func__);
> >> +
> >> +	/* mark it as detached */
> >> +	of_node_set_flag(overlay->overlay, OF_DETACHED);
> >> +
> >> +	/* perform resolution */
> >> +	err = of_resolve_phandles(overlay->overlay);
> >> +	if (err != 0) {
> >> +		pr_err("%s: Failed to resolve tree\n", __func__);
> >> +		goto out_err;
> >> +	}
> >> +	pr_debug("%s: resolved OK\n", __func__);
> >> +
> >> +	err = of_overlay_create(overlay->overlay);
> >> +	if (err < 0) {
> >> +		pr_err("%s: Failed to create overlay (err=%d)\n",
> >> +				__func__, err);
> >> +		goto out_err;
> >> +	}
> >> +	overlay->ov_id = err;
> >> +
> >> +out_err:
> >> +	return err;
> >> +}
> >> +
> >> +static inline struct cfs_overlay_item *to_cfs_overlay_item(
> >> +		struct config_item *item)
> >> +{
> >> +	return item ? container_of(item, struct cfs_overlay_item, item) : NULL;
> >> +}
> >> +
> >> +CONFIGFS_ATTR_STRUCT(cfs_overlay_item);
> >> +#define CFS_OVERLAY_ITEM_ATTR(_name, _mode, _show, _store)	\
> >> +struct cfs_overlay_item_attribute cfs_overlay_item_attr_##_name = \
> >> +	__CONFIGFS_ATTR(_name, _mode, _show, _store)
> >> +#define CFS_OVERLAY_ITEM_ATTR_RO(_name, _show)	\
> >> +struct cfs_overlay_item_attribute cfs_overlay_item_attr_##_name = \
> >> +	__CONFIGFS_ATTR_RO(_name, _show)
> >> +
> >> +CONFIGFS_BIN_ATTR_STRUCT(cfs_overlay_item);
> >> +#define CFS_OVERLAY_ITEM_BIN_ATTR(_name, _mode, _read, _write, _priv, _max) \
> >> +struct cfs_overlay_item_bin_attribute cfs_overlay_item_bin_attr_##_name = \
> >> +	__CONFIGFS_BIN_ATTR(_name, _mode, _read, _write, _priv, _max)
> >> +#define CFS_OVERLAY_ITEM_BIN_ATTR_RO(_name, _read, _priv, _max)	\
> >> +struct cfs_overlay_item_bin_attribute cfs_overlay_item_bin_attr_##_name = \
> >> +	__CONFIGFS_BIN_ATTR_RO(_name, _read, _priv, _max)
> >> +
> >> +static ssize_t cfs_overlay_item_path_show(struct cfs_overlay_item *overlay,
> >> +		char *page)
> >> +{
> >> +	return sprintf(page, "%s\n", overlay->path);
> >> +}
> >> +
> >> +static ssize_t cfs_overlay_item_path_store(struct cfs_overlay_item *overlay,
> >> +		const char *page, size_t count)
> >> +{
> >> +	const char *p = page;
> >> +	char *s;
> >> +	int err;
> >> +
> >> +	/* if it's set do not allow changes */
> >> +	if (overlay->path[0] != '\0' || overlay->dtbo_size > 0)
> >> +		return -EPERM;
> >> +
> >> +	/* copy to path buffer (and make sure it's always zero terminated */
> >> +	count = snprintf(overlay->path, sizeof(overlay->path) - 1, "%s", p);
> >> +	overlay->path[sizeof(overlay->path) - 1] = '\0';
> >> +
> >> +	/* strip trailing newlines */
> >> +	s = overlay->path + strlen(overlay->path);
> >> +	while (s > overlay->path && *--s == '\n')
> >> +		*s = '\0';
> >> +
> >> +	pr_debug("%s: path is '%s'\n", __func__, overlay->path);
> >> +
> >> +	err = request_firmware(&overlay->fw, overlay->path, NULL);
> >> +	if (err != 0)
> >> +		goto out_err;
> >> +
> >> +	err = create_overlay(overlay, (void *)overlay->fw->data);
> >> +	if (err != 0)
> >> +		goto out_err;
> >> +
> >> +	return count;
> >> +
> >> +out_err:
> >> +
> >> +	release_firmware(overlay->fw);
> >> +	overlay->fw = NULL;
> >> +
> >> +	overlay->path[0] = '\0';
> >> +	return err;
> >> +}
> >> +
> >> +static ssize_t cfs_overlay_item_status_show(struct cfs_overlay_item *overlay,
> >> +		char *page)
> >> +{
> >> +	return sprintf(page, "%s\n",
> >> +			overlay->ov_id >= 0 ? "applied" : "unapplied");
> >> +}
> >> +
> >> +CFS_OVERLAY_ITEM_ATTR(path, S_IRUGO | S_IWUSR,
> >> +		cfs_overlay_item_path_show, cfs_overlay_item_path_store);
> > 
> > World writable? Am I reading this correctly?
> > 
> 
> Err, user writeable, world readable. “-rw-r--r—"

Oops, I did read it wrong. Sorry for the noise

> > DT modifications are privileged. A user can potentially get arbitrary
> > access to i2c, spi, gpio or other things that shouldn't be allowed. This
> > feature give access right into the Linux driver model.
> > 
> 
> Yes, it does.
> 
> > Before this can be merged, it needs to be locked down, and there needs
> > to be documentation about how it is locked down. Owned by root is only
> > the first step, there also needs to be some rules about which nodes can
> > be modified by the configfs interface. By default think no modifications
> > should be allowed on a tree unless there are properties somewhere in the
> > tree that explicitly allow modifications to be performed.
> > 
> 
> TBH this is more of a debug level interface. The way I see it a different
> overlay manager, that’s tuned to the platform, should handle the overlay
> request and application, in a manner that’s not directly open to user
> control. For example in a beaglebone you’d have a ‘cape’ manager reading
> the i2c eeproms and request the overlays they match without any user-space
> implication.

Right.

> However, this is an interface that developers will use daily, so I agree
> that we need to look into the security model now before it’s too late.
> 
> How do you feel for something like this in chosen:
> 
> overlay-targets = “/ocp”, “/pinctrl”;

It's a reasonable proposal. I'd like to have some time to think on it
though. The other way to do it would be to add properties throughout the
tree that mask/unmask modifications by overlay. I think the overlays are
more a property of the board than a configurable boot time argument (so
not something that would normally go in /chosen)

g.
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[PATCH v8 5/8] of: i2c: Export single device registration method

[Pantelis Antoniou]

Dynamically inserting i2c client device nodes requires the use
of a single device registration method. Rework and export it.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
---
 drivers/i2c/i2c-core.c | 99 +++++++++++++++++++++++++++-----------------------
 include/linux/i2c.h    | 10 +++++
 2 files changed, 64 insertions(+), 45 deletions(-)

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 2f90ac6..e6da9d3 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -54,6 +54,7 @@
 #include <linux/acpi.h>
 #include <linux/jump_label.h>
 #include <asm/uaccess.h>
+#include <linux/err.h>
 
 #include "i2c-core.h"
 
@@ -1370,63 +1371,71 @@ static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
 /* OF support code */
 
 #if IS_ENABLED(CONFIG_OF)
-static void of_i2c_register_devices(struct i2c_adapter *adap)
+struct i2c_client *
+of_i2c_register_device(struct i2c_adapter *adap,
+		struct device_node *node)
 {
-	void *result;
-	struct device_node *node;
+	struct i2c_client *result;
+	struct i2c_board_info info = {};
+	struct dev_archdata dev_ad = {};
+	const __be32 *addr;
+	int len;
 
-	/* Only register child devices if the adapter has a node pointer set */
-	if (!adap->dev.of_node)
-		return;
+	dev_dbg(&adap->dev, "of_i2c: register %s\n", node->full_name);
 
-	dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");
+	if (of_modalias_node(node, info.type, sizeof(info.type)) < 0) {
+		dev_err(&adap->dev, "of_i2c: modalias failure on %s\n",
+			node->full_name);
+		return ERR_PTR(-EINVAL);
+	}
 
-	for_each_available_child_of_node(adap->dev.of_node, node) {
-		struct i2c_board_info info = {};
-		struct dev_archdata dev_ad = {};
-		const __be32 *addr;
-		int len;
+	addr = of_get_property(node, "reg", &len);
+	if (!addr || (len < sizeof(int))) {
+		dev_err(&adap->dev, "of_i2c: invalid reg on %s\n",
+			node->full_name);
+		return ERR_PTR(-EINVAL);
+	}
 
-		dev_dbg(&adap->dev, "of_i2c: register %s\n", node->full_name);
+	info.addr = be32_to_cpup(addr);
+	if (info.addr > (1 << 10) - 1) {
+		dev_err(&adap->dev, "of_i2c: invalid addr=%x on %s\n",
+			info.addr, node->full_name);
+		return ERR_PTR(-EINVAL);
+	}
 
-		if (of_modalias_node(node, info.type, sizeof(info.type)) < 0) {
-			dev_err(&adap->dev, "of_i2c: modalias failure on %s\n",
-				node->full_name);
-			continue;
-		}
+	info.irq = irq_of_parse_and_map(node, 0);
+	info.of_node = of_node_get(node);
+	info.archdata = &dev_ad;
 
-		addr = of_get_property(node, "reg", &len);
-		if (!addr || (len < sizeof(int))) {
-			dev_err(&adap->dev, "of_i2c: invalid reg on %s\n",
-				node->full_name);
-			continue;
-		}
+	if (of_get_property(node, "wakeup-source", NULL))
+		info.flags |= I2C_CLIENT_WAKE;
 
-		info.addr = be32_to_cpup(addr);
-		if (info.addr > (1 << 10) - 1) {
-			dev_err(&adap->dev, "of_i2c: invalid addr=%x on %s\n",
-				info.addr, node->full_name);
-			continue;
-		}
+	request_module("%s%s", I2C_MODULE_PREFIX, info.type);
 
-		info.irq = irq_of_parse_and_map(node, 0);
-		info.of_node = of_node_get(node);
-		info.archdata = &dev_ad;
+	result = i2c_new_device(adap, &info);
+	if (result == NULL) {
+		dev_err(&adap->dev, "of_i2c: Failure registering %s\n",
+			node->full_name);
+		of_node_put(node);
+		irq_dispose_mapping(info.irq);
+		return ERR_PTR(-EINVAL);
+	}
+	return result;
+}
+EXPORT_SYMBOL(of_i2c_register_device);
 
-		if (of_get_property(node, "wakeup-source", NULL))
-			info.flags |= I2C_CLIENT_WAKE;
+static void of_i2c_register_devices(struct i2c_adapter *adap)
+{
+	struct device_node *node;
 
-		request_module("%s%s", I2C_MODULE_PREFIX, info.type);
+	/* Only register child devices if the adapter has a node pointer set */
+	if (!adap->dev.of_node)
+		return;
 
-		result = i2c_new_device(adap, &info);
-		if (result == NULL) {
-			dev_err(&adap->dev, "of_i2c: Failure registering %s\n",
-				node->full_name);
-			of_node_put(node);
-			irq_dispose_mapping(info.irq);
-			continue;
-		}
-	}
+	dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");
+
+	for_each_available_child_of_node(adap->dev.of_node, node)
+		of_i2c_register_device(adap, node);
 }
 
 static int of_dev_node_match(struct device *dev, void *data)
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index b556e0a..22a8f44 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -558,6 +558,9 @@ static inline int i2c_adapter_id(struct i2c_adapter *adap)
 #endif /* I2C */
 
 #if IS_ENABLED(CONFIG_OF)
+struct i2c_client *
+of_i2c_register_device(struct i2c_adapter *adap, struct device_node *node);
+
 /* must call put_device() when done with returned i2c_client device */
 extern struct i2c_client *of_find_i2c_device_by_node(struct device_node *node);
 
@@ -566,6 +569,13 @@ extern struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
 
 #else
 
+static inline struct i2c_client *
+of_i2c_register_device(struct i2c_adapter *adap,
+		struct device_node *node)
+{
+	return ERR_PTR(-ENODEV);
+}
+
 static inline struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
 {
 	return NULL;
-- 
1.7.12

Re: [PATCH v8 5/8] of: i2c: Export single device registration method

[Grant Likely]

On Tue, 28 Oct 2014 22:36:02 +0200
, Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
 wrote:
> Dynamically inserting i2c client device nodes requires the use
> of a single device registration method. Rework and export it.
> 
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>

Acked-by: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

Wolfram, this patch and the next one only make sense in conjunction with the overlay
patches, but they don't necessarily need to be merged via the same tree.
I'm happy to take them, but am equally happy to have you take them
(assuming I ack the next patch; I haven't looked at it yet). What is
your preference?

g.

> ---
>  drivers/i2c/i2c-core.c | 99 +++++++++++++++++++++++++++-----------------------
>  include/linux/i2c.h    | 10 +++++
>  2 files changed, 64 insertions(+), 45 deletions(-)
> 
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index 2f90ac6..e6da9d3 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -54,6 +54,7 @@
>  #include <linux/acpi.h>
>  #include <linux/jump_label.h>
>  #include <asm/uaccess.h>
> +#include <linux/err.h>
>  
>  #include "i2c-core.h"
>  
> @@ -1370,63 +1371,71 @@ static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
>  /* OF support code */
>  
>  #if IS_ENABLED(CONFIG_OF)
> -static void of_i2c_register_devices(struct i2c_adapter *adap)
> +struct i2c_client *
> +of_i2c_register_device(struct i2c_adapter *adap,
> +		struct device_node *node)
>  {
> -	void *result;
> -	struct device_node *node;
> +	struct i2c_client *result;
> +	struct i2c_board_info info = {};
> +	struct dev_archdata dev_ad = {};
> +	const __be32 *addr;
> +	int len;
>  
> -	/* Only register child devices if the adapter has a node pointer set */
> -	if (!adap->dev.of_node)
> -		return;
> +	dev_dbg(&adap->dev, "of_i2c: register %s\n", node->full_name);
>  
> -	dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");
> +	if (of_modalias_node(node, info.type, sizeof(info.type)) < 0) {
> +		dev_err(&adap->dev, "of_i2c: modalias failure on %s\n",
> +			node->full_name);
> +		return ERR_PTR(-EINVAL);
> +	}
>  
> -	for_each_available_child_of_node(adap->dev.of_node, node) {
> -		struct i2c_board_info info = {};
> -		struct dev_archdata dev_ad = {};
> -		const __be32 *addr;
> -		int len;
> +	addr = of_get_property(node, "reg", &len);
> +	if (!addr || (len < sizeof(int))) {
> +		dev_err(&adap->dev, "of_i2c: invalid reg on %s\n",
> +			node->full_name);
> +		return ERR_PTR(-EINVAL);
> +	}
>  
> -		dev_dbg(&adap->dev, "of_i2c: register %s\n", node->full_name);
> +	info.addr = be32_to_cpup(addr);
> +	if (info.addr > (1 << 10) - 1) {
> +		dev_err(&adap->dev, "of_i2c: invalid addr=%x on %s\n",
> +			info.addr, node->full_name);
> +		return ERR_PTR(-EINVAL);
> +	}
>  
> -		if (of_modalias_node(node, info.type, sizeof(info.type)) < 0) {
> -			dev_err(&adap->dev, "of_i2c: modalias failure on %s\n",
> -				node->full_name);
> -			continue;
> -		}
> +	info.irq = irq_of_parse_and_map(node, 0);
> +	info.of_node = of_node_get(node);
> +	info.archdata = &dev_ad;
>  
> -		addr = of_get_property(node, "reg", &len);
> -		if (!addr || (len < sizeof(int))) {
> -			dev_err(&adap->dev, "of_i2c: invalid reg on %s\n",
> -				node->full_name);
> -			continue;
> -		}
> +	if (of_get_property(node, "wakeup-source", NULL))
> +		info.flags |= I2C_CLIENT_WAKE;
>  
> -		info.addr = be32_to_cpup(addr);
> -		if (info.addr > (1 << 10) - 1) {
> -			dev_err(&adap->dev, "of_i2c: invalid addr=%x on %s\n",
> -				info.addr, node->full_name);
> -			continue;
> -		}
> +	request_module("%s%s", I2C_MODULE_PREFIX, info.type);
>  
> -		info.irq = irq_of_parse_and_map(node, 0);
> -		info.of_node = of_node_get(node);
> -		info.archdata = &dev_ad;
> +	result = i2c_new_device(adap, &info);
> +	if (result == NULL) {
> +		dev_err(&adap->dev, "of_i2c: Failure registering %s\n",
> +			node->full_name);
> +		of_node_put(node);
> +		irq_dispose_mapping(info.irq);
> +		return ERR_PTR(-EINVAL);
> +	}
> +	return result;
> +}
> +EXPORT_SYMBOL(of_i2c_register_device);
>  
> -		if (of_get_property(node, "wakeup-source", NULL))
> -			info.flags |= I2C_CLIENT_WAKE;
> +static void of_i2c_register_devices(struct i2c_adapter *adap)
> +{
> +	struct device_node *node;
>  
> -		request_module("%s%s", I2C_MODULE_PREFIX, info.type);
> +	/* Only register child devices if the adapter has a node pointer set */
> +	if (!adap->dev.of_node)
> +		return;
>  
> -		result = i2c_new_device(adap, &info);
> -		if (result == NULL) {
> -			dev_err(&adap->dev, "of_i2c: Failure registering %s\n",
> -				node->full_name);
> -			of_node_put(node);
> -			irq_dispose_mapping(info.irq);
> -			continue;
> -		}
> -	}
> +	dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");
> +
> +	for_each_available_child_of_node(adap->dev.of_node, node)
> +		of_i2c_register_device(adap, node);
>  }
>  
>  static int of_dev_node_match(struct device *dev, void *data)
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index b556e0a..22a8f44 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -558,6 +558,9 @@ static inline int i2c_adapter_id(struct i2c_adapter *adap)
>  #endif /* I2C */
>  
>  #if IS_ENABLED(CONFIG_OF)
> +struct i2c_client *
> +of_i2c_register_device(struct i2c_adapter *adap, struct device_node *node);
> +
>  /* must call put_device() when done with returned i2c_client device */
>  extern struct i2c_client *of_find_i2c_device_by_node(struct device_node *node);
>  
> @@ -566,6 +569,13 @@ extern struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
>  
>  #else
>  
> +static inline struct i2c_client *
> +of_i2c_register_device(struct i2c_adapter *adap,
> +		struct device_node *node)
> +{
> +	return ERR_PTR(-ENODEV);
> +}
> +
>  static inline struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
>  {
>  	return NULL;
> -- 
> 1.7.12
> 

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Re: [PATCH v8 5/8] of: i2c: Export single device registration method

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 1369 bytes --]

On Fri, Nov 21, 2014 at 01:46:31AM +0000, Grant Likely wrote:
> On Tue, 28 Oct 2014 22:36:02 +0200
> , Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
>  wrote:
> > Dynamically inserting i2c client device nodes requires the use
> > of a single device registration method. Rework and export it.
> > 
> > Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
> 
> Acked-by: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> 
> Wolfram, this patch and the next one only make sense in conjunction with the overlay
> patches, but they don't necessarily need to be merged via the same tree.
> I'm happy to take them, but am equally happy to have you take them
> (assuming I ack the next patch; I haven't looked at it yet). What is
> your preference?

OK, now I had the time to look at it, phew.

Is this targetted for 3.19? Then you can take it:
Reviewed-by: Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>

There is a minor conflict caused by this patch in i2c/for-next which
should be easy to solve, just remove the irq handling.

2fd36c552649 2014-10-30 15:59 Laurent Pinchart   o i2c: core: Map OF IRQ at probe time

If you target for later than 3.19, then we need to discuss again,
because there might be other i2c core changes coming in.


[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]

[PATCH v8 6/8] OF: i2c: Add OF notifier handler

[Pantelis Antoniou]

Add OF notifier handler needed for creating/destroying i2c devices
according to dynamic runtime changes in the DT live tree.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
---
 drivers/i2c/i2c-core.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 78 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index e6da9d3..e751b78 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1470,6 +1470,7 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
 	return i2c_verify_adapter(dev);
 }
 EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
+
 #else
 static void of_i2c_register_devices(struct i2c_adapter *adap) { }
 #endif /* CONFIG_OF */
@@ -1955,6 +1956,71 @@ void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
 }
 EXPORT_SYMBOL(i2c_clients_command);
 
+#if IS_ENABLED(CONFIG_OF)
+
+static int of_i2c_notify(struct notifier_block *nb,
+				unsigned long action, void *arg)
+{
+	struct device_node *dn;
+	struct i2c_adapter *adap;
+	struct i2c_client *client;
+	int state;
+
+	state = of_reconfig_get_state_change(action, arg);
+	if (state == -1)
+		return NOTIFY_OK;
+
+	switch (action) {
+	case OF_RECONFIG_ATTACH_NODE:
+	case OF_RECONFIG_DETACH_NODE:
+		dn = arg;
+		break;
+	case OF_RECONFIG_ADD_PROPERTY:
+	case OF_RECONFIG_REMOVE_PROPERTY:
+	case OF_RECONFIG_UPDATE_PROPERTY:
+		dn = ((struct of_prop_reconfig *)arg)->dn;
+		break;
+	default:
+		return NOTIFY_OK;
+	}
+
+	if (state) {
+
+		adap = of_find_i2c_adapter_by_node(dn->parent);
+		if (adap == NULL)
+			return NOTIFY_OK;	/* not for us */
+
+		client = of_i2c_register_device(adap, dn);
+		put_device(&adap->dev);
+
+		if (IS_ERR(client)) {
+			pr_err("%s: failed to create for '%s'\n",
+					__func__, dn->full_name);
+			return notifier_from_errno(PTR_ERR(client));
+		}
+
+	} else {
+
+		/* find our device by node */
+		client = of_find_i2c_device_by_node(dn);
+		if (client == NULL)
+			return NOTIFY_OK;	/* no? not meant for us */
+
+		/* unregister takes one ref away */
+		i2c_unregister_device(client);
+
+		/* and put the reference of the find */
+		put_device(&client->dev);
+
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block i2c_of_notifier;
+
+#endif
+
 static int __init i2c_init(void)
 {
 	int retval;
@@ -1972,8 +2038,19 @@ static int __init i2c_init(void)
 	retval = i2c_add_driver(&dummy_driver);
 	if (retval)
 		goto class_err;
-	return 0;
 
+#if IS_ENABLED(CONFIG_OF)
+	i2c_of_notifier.notifier_call = of_i2c_notify;
+	retval = of_reconfig_notifier_register(&i2c_of_notifier);
+	if (retval)
+		goto notifier_err;
+#endif
+
+	return 0;
+#if IS_ENABLED(CONFIG_OF)
+notifier_err:
+	i2c_del_driver(&dummy_driver);
+#endif
 class_err:
 #ifdef CONFIG_I2C_COMPAT
 	class_compat_unregister(i2c_adapter_compat_class);
-- 
1.7.12

Re: [PATCH v8 6/8] OF: i2c: Add OF notifier handler

[Grant Likely]

On Tue, 28 Oct 2014 22:36:03 +0200
, Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
 wrote:
> Add OF notifier handler needed for creating/destroying i2c devices
> according to dynamic runtime changes in the DT live tree.
> 
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
> ---
>  drivers/i2c/i2c-core.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 78 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index e6da9d3..e751b78 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -1470,6 +1470,7 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
>  	return i2c_verify_adapter(dev);
>  }
>  EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
> +
>  #else
>  static void of_i2c_register_devices(struct i2c_adapter *adap) { }
>  #endif /* CONFIG_OF */
> @@ -1955,6 +1956,71 @@ void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
>  }
>  EXPORT_SYMBOL(i2c_clients_command);
>  
> +#if IS_ENABLED(CONFIG_OF)
> +
> +static int of_i2c_notify(struct notifier_block *nb,
> +				unsigned long action, void *arg)
> +{
> +	struct device_node *dn;
> +	struct i2c_adapter *adap;
> +	struct i2c_client *client;
> +	int state;
> +
> +	state = of_reconfig_get_state_change(action, arg);
> +	if (state == -1)
> +		return NOTIFY_OK;
> +
> +	switch (action) {
> +	case OF_RECONFIG_ATTACH_NODE:
> +	case OF_RECONFIG_DETACH_NODE:
> +		dn = arg;
> +		break;
> +	case OF_RECONFIG_ADD_PROPERTY:
> +	case OF_RECONFIG_REMOVE_PROPERTY:
> +	case OF_RECONFIG_UPDATE_PROPERTY:
> +		dn = ((struct of_prop_reconfig *)arg)->dn;
> +		break;
> +	default:
> +		return NOTIFY_OK;
> +	}
> +
> +	if (state) {
> +
> +		adap = of_find_i2c_adapter_by_node(dn->parent);
> +		if (adap == NULL)
> +			return NOTIFY_OK;	/* not for us */
> +
> +		client = of_i2c_register_device(adap, dn);
> +		put_device(&adap->dev);
> +
> +		if (IS_ERR(client)) {
> +			pr_err("%s: failed to create for '%s'\n",
> +					__func__, dn->full_name);
> +			return notifier_from_errno(PTR_ERR(client));
> +		}
> +
> +	} else {
> +
> +		/* find our device by node */
> +		client = of_find_i2c_device_by_node(dn);
> +		if (client == NULL)
> +			return NOTIFY_OK;	/* no? not meant for us */
> +
> +		/* unregister takes one ref away */
> +		i2c_unregister_device(client);
> +
> +		/* and put the reference of the find */
> +		put_device(&client->dev);
> +
> +	}

Nit: odd whitespace

> +
> +	return NOTIFY_OK;
> +}
> +
> +static struct notifier_block i2c_of_notifier;
> +
> +#endif
> +
>  static int __init i2c_init(void)
>  {
>  	int retval;
> @@ -1972,8 +2038,19 @@ static int __init i2c_init(void)
>  	retval = i2c_add_driver(&dummy_driver);
>  	if (retval)
>  		goto class_err;
> -	return 0;
>  
> +#if IS_ENABLED(CONFIG_OF)
> +	i2c_of_notifier.notifier_call = of_i2c_notify;
> +	retval = of_reconfig_notifier_register(&i2c_of_notifier);
> +	if (retval)
> +		goto notifier_err;
> +#endif
> +
> +	return 0;
> +#if IS_ENABLED(CONFIG_OF)
> +notifier_err:
> +	i2c_del_driver(&dummy_driver);
> +#endif

Similar to my comment on the platform bus, don't break the entire bus if
registration of the notifier fails. I would drop the error case and just
do a WARN_ON() if it fails.

Otherwise:

Acked-by: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

>  class_err:
>  #ifdef CONFIG_I2C_COMPAT
>  	class_compat_unregister(i2c_adapter_compat_class);
> -- 
> 1.7.12
> 

Re: [PATCH v8 6/8] OF: i2c: Add OF notifier handler

[Guenter Roeck]

On 11/20/2014 05:53 PM, Grant Likely wrote:
> On Tue, 28 Oct 2014 22:36:03 +0200
> , Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>   wrote:
>> Add OF notifier handler needed for creating/destroying i2c devices
>> according to dynamic runtime changes in the DT live tree.
>>
>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>> ---
>>   drivers/i2c/i2c-core.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 78 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
>> index e6da9d3..e751b78 100644
>> --- a/drivers/i2c/i2c-core.c
>> +++ b/drivers/i2c/i2c-core.c
>> @@ -1470,6 +1470,7 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
>>   	return i2c_verify_adapter(dev);
>>   }
>>   EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
>> +
>>   #else
>>   static void of_i2c_register_devices(struct i2c_adapter *adap) { }
>>   #endif /* CONFIG_OF */
>> @@ -1955,6 +1956,71 @@ void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
>>   }
>>   EXPORT_SYMBOL(i2c_clients_command);
>>
>> +#if IS_ENABLED(CONFIG_OF)
>> +
>> +static int of_i2c_notify(struct notifier_block *nb,
>> +				unsigned long action, void *arg)
>> +{
>> +	struct device_node *dn;
>> +	struct i2c_adapter *adap;
>> +	struct i2c_client *client;
>> +	int state;
>> +
>> +	state = of_reconfig_get_state_change(action, arg);
>> +	if (state == -1)
>> +		return NOTIFY_OK;
>> +
>> +	switch (action) {
>> +	case OF_RECONFIG_ATTACH_NODE:
>> +	case OF_RECONFIG_DETACH_NODE:
>> +		dn = arg;
>> +		break;
>> +	case OF_RECONFIG_ADD_PROPERTY:
>> +	case OF_RECONFIG_REMOVE_PROPERTY:
>> +	case OF_RECONFIG_UPDATE_PROPERTY:
>> +		dn = ((struct of_prop_reconfig *)arg)->dn;
>> +		break;
>> +	default:
>> +		return NOTIFY_OK;
>> +	}
>> +
>> +	if (state) {
>> +
>> +		adap = of_find_i2c_adapter_by_node(dn->parent);
>> +		if (adap == NULL)
>> +			return NOTIFY_OK;	/* not for us */
>> +
>> +		client = of_i2c_register_device(adap, dn);
>> +		put_device(&adap->dev);
>> +
>> +		if (IS_ERR(client)) {
>> +			pr_err("%s: failed to create for '%s'\n",
>> +					__func__, dn->full_name);
>> +			return notifier_from_errno(PTR_ERR(client));
>> +		}
>> +
>> +	} else {
>> +
>> +		/* find our device by node */
>> +		client = of_find_i2c_device_by_node(dn);
>> +		if (client == NULL)
>> +			return NOTIFY_OK;	/* no? not meant for us */
>> +
>> +		/* unregister takes one ref away */
>> +		i2c_unregister_device(client);
>> +
>> +		/* and put the reference of the find */
>> +		put_device(&client->dev);
>> +
>> +	}
>
> Nit: odd whitespace
>
>> +
>> +	return NOTIFY_OK;
>> +}
>> +
>> +static struct notifier_block i2c_of_notifier;
>> +
>> +#endif
>> +
>>   static int __init i2c_init(void)
>>   {
>>   	int retval;
>> @@ -1972,8 +2038,19 @@ static int __init i2c_init(void)
>>   	retval = i2c_add_driver(&dummy_driver);
>>   	if (retval)
>>   		goto class_err;
>> -	return 0;
>>
>> +#if IS_ENABLED(CONFIG_OF)
>> +	i2c_of_notifier.notifier_call = of_i2c_notify;

Wouldn't it be easier to just initialize i2c_of_notifier above instead of
here in the code ? Or is there a reason for doing it here ?

Thanks,
Guenter

>> +	retval = of_reconfig_notifier_register(&i2c_of_notifier);
>> +	if (retval)
>> +		goto notifier_err;
>> +#endif
>> +
>> +	return 0;
>> +#if IS_ENABLED(CONFIG_OF)
>> +notifier_err:
>> +	i2c_del_driver(&dummy_driver);
>> +#endif
>
> Similar to my comment on the platform bus, don't break the entire bus if
> registration of the notifier fails. I would drop the error case and just
> do a WARN_ON() if it fails.
>
> Otherwise:
>
> Acked-by: Grant Likely <grant.likely@linaro.org>
>
>>   class_err:
>>   #ifdef CONFIG_I2C_COMPAT
>>   	class_compat_unregister(i2c_adapter_compat_class);
>> --
>> 1.7.12
>>
>
>

Re: [PATCH v8 6/8] OF: i2c: Add OF notifier handler

[Grant Likely]

On Thu, 20 Nov 2014 18:03:33 -0800
, Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
 wrote:
> On 11/20/2014 05:53 PM, Grant Likely wrote:
> > On Tue, 28 Oct 2014 22:36:03 +0200
> > , Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
> >   wrote:
> >> Add OF notifier handler needed for creating/destroying i2c devices
> >> according to dynamic runtime changes in the DT live tree.
> >>
> >> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
> >> ---
> >>   drivers/i2c/i2c-core.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++-
> >>   1 file changed, 78 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> >> index e6da9d3..e751b78 100644
> >> --- a/drivers/i2c/i2c-core.c
> >> +++ b/drivers/i2c/i2c-core.c
> >> @@ -1470,6 +1470,7 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
> >>   	return i2c_verify_adapter(dev);
> >>   }
> >>   EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
> >> +
> >>   #else
> >>   static void of_i2c_register_devices(struct i2c_adapter *adap) { }
> >>   #endif /* CONFIG_OF */
> >> @@ -1955,6 +1956,71 @@ void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
> >>   }
> >>   EXPORT_SYMBOL(i2c_clients_command);
> >>
> >> +#if IS_ENABLED(CONFIG_OF)
> >> +
> >> +static int of_i2c_notify(struct notifier_block *nb,
> >> +				unsigned long action, void *arg)
> >> +{
> >> +	struct device_node *dn;
> >> +	struct i2c_adapter *adap;
> >> +	struct i2c_client *client;
> >> +	int state;
> >> +
> >> +	state = of_reconfig_get_state_change(action, arg);
> >> +	if (state == -1)
> >> +		return NOTIFY_OK;
> >> +
> >> +	switch (action) {
> >> +	case OF_RECONFIG_ATTACH_NODE:
> >> +	case OF_RECONFIG_DETACH_NODE:
> >> +		dn = arg;
> >> +		break;
> >> +	case OF_RECONFIG_ADD_PROPERTY:
> >> +	case OF_RECONFIG_REMOVE_PROPERTY:
> >> +	case OF_RECONFIG_UPDATE_PROPERTY:
> >> +		dn = ((struct of_prop_reconfig *)arg)->dn;
> >> +		break;
> >> +	default:
> >> +		return NOTIFY_OK;
> >> +	}
> >> +
> >> +	if (state) {
> >> +
> >> +		adap = of_find_i2c_adapter_by_node(dn->parent);
> >> +		if (adap == NULL)
> >> +			return NOTIFY_OK;	/* not for us */
> >> +
> >> +		client = of_i2c_register_device(adap, dn);
> >> +		put_device(&adap->dev);
> >> +
> >> +		if (IS_ERR(client)) {
> >> +			pr_err("%s: failed to create for '%s'\n",
> >> +					__func__, dn->full_name);
> >> +			return notifier_from_errno(PTR_ERR(client));
> >> +		}
> >> +
> >> +	} else {
> >> +
> >> +		/* find our device by node */
> >> +		client = of_find_i2c_device_by_node(dn);
> >> +		if (client == NULL)
> >> +			return NOTIFY_OK;	/* no? not meant for us */
> >> +
> >> +		/* unregister takes one ref away */
> >> +		i2c_unregister_device(client);
> >> +
> >> +		/* and put the reference of the find */
> >> +		put_device(&client->dev);
> >> +
> >> +	}
> >
> > Nit: odd whitespace
> >
> >> +
> >> +	return NOTIFY_OK;
> >> +}
> >> +
> >> +static struct notifier_block i2c_of_notifier;
> >> +
> >> +#endif
> >> +
> >>   static int __init i2c_init(void)
> >>   {
> >>   	int retval;
> >> @@ -1972,8 +2038,19 @@ static int __init i2c_init(void)
> >>   	retval = i2c_add_driver(&dummy_driver);
> >>   	if (retval)
> >>   		goto class_err;
> >> -	return 0;
> >>
> >> +#if IS_ENABLED(CONFIG_OF)
> >> +	i2c_of_notifier.notifier_call = of_i2c_notify;
> 
> Wouldn't it be easier to just initialize i2c_of_notifier above instead of
> here in the code ? Or is there a reason for doing it here ?

Yes, absolutely. This code should also depend on CONFIG_OF_DYNAMIC too,
not merely CONFIG_OF.

> 
> Thanks,
> Guenter
> 
> >> +	retval = of_reconfig_notifier_register(&i2c_of_notifier);
> >> +	if (retval)
> >> +		goto notifier_err;
> >> +#endif

We can also get rid of the ugly #ifdef in the body by creating empty
stubs for of_reconfig_notify_{register,unregister}() and doing the
following:

	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
		WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier))

I picked up the patch into my tree and made the above changes because
they're pretty trivial. If Wolfram is okay with it then I can take the
whole series through my tree. Otherwise I'll put the of_reconfig_* empty
stubs into a separate branch that he and broonie can both pull.

g.

> >> +
> >> +	return 0;
> >> +#if IS_ENABLED(CONFIG_OF)
> >> +notifier_err:
> >> +	i2c_del_driver(&dummy_driver);
> >> +#endif
> >
> > Similar to my comment on the platform bus, don't break the entire bus if
> > registration of the notifier fails. I would drop the error case and just
> > do a WARN_ON() if it fails.
> >
> > Otherwise:
> >
> > Acked-by: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> >
> >>   class_err:
> >>   #ifdef CONFIG_I2C_COMPAT
> >>   	class_compat_unregister(i2c_adapter_compat_class);
> >> --
> >> 1.7.12
> >>
> >
> >
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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> Please read the FAQ at  http://www.tux.org/lkml/

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Re: [PATCH v8 6/8] OF: i2c: Add OF notifier handler

[Pantelis Antoniou]

Hi Grant,

> On Nov 21, 2014, at 17:08 , Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> wrote:
> 
> On Thu, 20 Nov 2014 18:03:33 -0800
> , Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
> wrote:
>> On 11/20/2014 05:53 PM, Grant Likely wrote:
>>> On Tue, 28 Oct 2014 22:36:03 +0200
>>> , Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
>>>  wrote:
>>>> Add OF notifier handler needed for creating/destroying i2c devices
>>>> according to dynamic runtime changes in the DT live tree.
>>>> 
>>>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
>>>> ---
>>>>  drivers/i2c/i2c-core.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++-
>>>>  1 file changed, 78 insertions(+), 1 deletion(-)
>>>> 
>>>> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
>>>> index e6da9d3..e751b78 100644
>>>> --- a/drivers/i2c/i2c-core.c
>>>> +++ b/drivers/i2c/i2c-core.c
>>>> @@ -1470,6 +1470,7 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
>>>>  	return i2c_verify_adapter(dev);
>>>>  }
>>>>  EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
>>>> +
>>>>  #else
>>>>  static void of_i2c_register_devices(struct i2c_adapter *adap) { }
>>>>  #endif /* CONFIG_OF */
>>>> @@ -1955,6 +1956,71 @@ void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
>>>>  }
>>>>  EXPORT_SYMBOL(i2c_clients_command);
>>>> 
>>>> +#if IS_ENABLED(CONFIG_OF)
>>>> +
>>>> +static int of_i2c_notify(struct notifier_block *nb,
>>>> +				unsigned long action, void *arg)
>>>> +{
>>>> +	struct device_node *dn;
>>>> +	struct i2c_adapter *adap;
>>>> +	struct i2c_client *client;
>>>> +	int state;
>>>> +
>>>> +	state = of_reconfig_get_state_change(action, arg);
>>>> +	if (state == -1)
>>>> +		return NOTIFY_OK;
>>>> +
>>>> +	switch (action) {
>>>> +	case OF_RECONFIG_ATTACH_NODE:
>>>> +	case OF_RECONFIG_DETACH_NODE:
>>>> +		dn = arg;
>>>> +		break;
>>>> +	case OF_RECONFIG_ADD_PROPERTY:
>>>> +	case OF_RECONFIG_REMOVE_PROPERTY:
>>>> +	case OF_RECONFIG_UPDATE_PROPERTY:
>>>> +		dn = ((struct of_prop_reconfig *)arg)->dn;
>>>> +		break;
>>>> +	default:
>>>> +		return NOTIFY_OK;
>>>> +	}
>>>> +
>>>> +	if (state) {
>>>> +
>>>> +		adap = of_find_i2c_adapter_by_node(dn->parent);
>>>> +		if (adap == NULL)
>>>> +			return NOTIFY_OK;	/* not for us */
>>>> +
>>>> +		client = of_i2c_register_device(adap, dn);
>>>> +		put_device(&adap->dev);
>>>> +
>>>> +		if (IS_ERR(client)) {
>>>> +			pr_err("%s: failed to create for '%s'\n",
>>>> +					__func__, dn->full_name);
>>>> +			return notifier_from_errno(PTR_ERR(client));
>>>> +		}
>>>> +
>>>> +	} else {
>>>> +
>>>> +		/* find our device by node */
>>>> +		client = of_find_i2c_device_by_node(dn);
>>>> +		if (client == NULL)
>>>> +			return NOTIFY_OK;	/* no? not meant for us */
>>>> +
>>>> +		/* unregister takes one ref away */
>>>> +		i2c_unregister_device(client);
>>>> +
>>>> +		/* and put the reference of the find */
>>>> +		put_device(&client->dev);
>>>> +
>>>> +	}
>>> 
>>> Nit: odd whitespace
>>> 
>>>> +
>>>> +	return NOTIFY_OK;
>>>> +}
>>>> +
>>>> +static struct notifier_block i2c_of_notifier;
>>>> +
>>>> +#endif
>>>> +
>>>>  static int __init i2c_init(void)
>>>>  {
>>>>  	int retval;
>>>> @@ -1972,8 +2038,19 @@ static int __init i2c_init(void)
>>>>  	retval = i2c_add_driver(&dummy_driver);
>>>>  	if (retval)
>>>>  		goto class_err;
>>>> -	return 0;
>>>> 
>>>> +#if IS_ENABLED(CONFIG_OF)
>>>> +	i2c_of_notifier.notifier_call = of_i2c_notify;
>> 
>> Wouldn't it be easier to just initialize i2c_of_notifier above instead of
>> here in the code ? Or is there a reason for doing it here ?
> 
> Yes, absolutely. This code should also depend on CONFIG_OF_DYNAMIC too,
> not merely CONFIG_OF.
> 
>> 

No reason; it just seemed like the most opportune place to put it at the time.

>> Thanks,
>> Guenter
>> 
>>>> +	retval = of_reconfig_notifier_register(&i2c_of_notifier);
>>>> +	if (retval)
>>>> +		goto notifier_err;
>>>> +#endif
> 
> We can also get rid of the ugly #ifdef in the body by creating empty
> stubs for of_reconfig_notify_{register,unregister}() and doing the
> following:
> 
> 	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
> 		WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier))
> 
> I picked up the patch into my tree and made the above changes because
> they're pretty trivial. If Wolfram is okay with it then I can take the
> whole series through my tree. Otherwise I'll put the of_reconfig_* empty
> stubs into a separate branch that he and broonie can both pull.
> 

I’m fine with doing this if you’d like, it’s pretty simple.

Regards

— Pantelis

> g.
> 
>>>> +
>>>> +	return 0;
>>>> +#if IS_ENABLED(CONFIG_OF)
>>>> +notifier_err:
>>>> +	i2c_del_driver(&dummy_driver);
>>>> +#endif
>>> 
>>> Similar to my comment on the platform bus, don't break the entire bus if
>>> registration of the notifier fails. I would drop the error case and just
>>> do a WARN_ON() if it fails.
>>> 
>>> Otherwise:
>>> 
>>> Acked-by: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
>>> 
>>>>  class_err:
>>>>  #ifdef CONFIG_I2C_COMPAT
>>>>  	class_compat_unregister(i2c_adapter_compat_class);
>>>> --
>>>> 1.7.12
>>>> 
>>> 
>>> 
>> 
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
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>> Please read the FAQ at  http://www.tux.org/lkml/

Re: [PATCH v8 6/8] OF: i2c: Add OF notifier handler

[Wolfram Sang]

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> I picked up the patch into my tree and made the above changes because
> they're pretty trivial. If Wolfram is okay with it then I can take the
> whole series through my tree. Otherwise I'll put the of_reconfig_* empty
> stubs into a separate branch that he and broonie can both pull.

With your fix applied and in case of targetting 3.19:

Reviewed-by: Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>


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[PATCH v8 7/8] of: spi: Export single device registration method and accessors

[Pantelis Antoniou]

Dynamically inserting spi device nodes requires the use of a single
device registration method. Rework and export it.

Methods to lookup a device/master using a device node are added
as well, of_find_spi_master_by_node() & of_find_spi_device_by_node().

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
---
 drivers/spi/spi.c | 256 +++++++++++++++++++++++++++++++++---------------------
 1 file changed, 158 insertions(+), 98 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index ebcb33d..f81d799 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1220,6 +1220,123 @@ err_init_queue:
 /*-------------------------------------------------------------------------*/
 
 #if defined(CONFIG_OF)
+
+static struct spi_device *
+of_register_spi_device(struct spi_master *master, struct device_node *node)
+{
+	struct spi_device *spi;
+	struct device_node *nc;
+	int rc;
+	u32 value;
+
+	/* Alloc an spi_device */
+	spi = spi_alloc_device(master);
+	if (!spi) {
+		dev_err(&master->dev, "spi_device alloc error for %s\n",
+			nc->full_name);
+		rc = -ENOMEM;
+		goto err_out;
+	}
+
+	/* Select device driver */
+	rc = of_modalias_node(nc, spi->modalias,
+				sizeof(spi->modalias));
+	if (rc < 0) {
+		dev_err(&master->dev, "cannot find modalias for %s\n",
+			nc->full_name);
+		goto err_out;
+	}
+
+	/* Device address */
+	rc = of_property_read_u32(nc, "reg", &value);
+	if (rc) {
+		dev_err(&master->dev, "%s has no valid 'reg' property (%d)\n",
+			nc->full_name, rc);
+		goto err_out;
+	}
+	spi->chip_select = value;
+
+	/* Mode (clock phase/polarity/etc.) */
+	if (of_find_property(nc, "spi-cpha", NULL))
+		spi->mode |= SPI_CPHA;
+	if (of_find_property(nc, "spi-cpol", NULL))
+		spi->mode |= SPI_CPOL;
+	if (of_find_property(nc, "spi-cs-high", NULL))
+		spi->mode |= SPI_CS_HIGH;
+	if (of_find_property(nc, "spi-3wire", NULL))
+		spi->mode |= SPI_3WIRE;
+	if (of_find_property(nc, "spi-lsb-first", NULL))
+		spi->mode |= SPI_LSB_FIRST;
+
+	/* Device DUAL/QUAD mode */
+	if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
+		switch (value) {
+		case 1:
+			break;
+		case 2:
+			spi->mode |= SPI_TX_DUAL;
+			break;
+		case 4:
+			spi->mode |= SPI_TX_QUAD;
+			break;
+		default:
+			dev_warn(&master->dev,
+				"spi-tx-bus-width %d not supported\n",
+				value);
+			break;
+		}
+	}
+
+	if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
+		switch (value) {
+		case 1:
+			break;
+		case 2:
+			spi->mode |= SPI_RX_DUAL;
+			break;
+		case 4:
+			spi->mode |= SPI_RX_QUAD;
+			break;
+		default:
+			dev_warn(&master->dev,
+				"spi-rx-bus-width %d not supported\n",
+				value);
+			break;
+		}
+	}
+
+	/* Device speed */
+	rc = of_property_read_u32(nc, "spi-max-frequency", &value);
+	if (rc) {
+		dev_err(&master->dev, "%s has no valid 'spi-max-frequency' property (%d)\n",
+			nc->full_name, rc);
+		goto err_out;
+	}
+	spi->max_speed_hz = value;
+
+	/* IRQ */
+	spi->irq = irq_of_parse_and_map(nc, 0);
+
+	/* Store a pointer to the node in the device structure */
+	of_node_get(nc);
+	spi->dev.of_node = nc;
+
+	/* Register the new device */
+	request_module("%s%s", SPI_MODULE_PREFIX, spi->modalias);
+	rc = spi_add_device(spi);
+	if (rc) {
+		dev_err(&master->dev, "spi_device register error %s\n",
+			nc->full_name);
+		goto err_out;
+	}
+
+	return spi;
+
+err_out:
+	spi_dev_put(spi);
+	return ERR_PTR(rc);
+}
+
 /**
  * of_register_spi_devices() - Register child devices onto the SPI bus
  * @master:	Pointer to spi_master device
@@ -1229,120 +1346,63 @@ err_init_queue:
  */
 static void of_register_spi_devices(struct spi_master *master)
 {
-	struct spi_device *spi;
 	struct device_node *nc;
-	int rc;
-	u32 value;
+	struct spi_device *spi;
 
 	if (!master->dev.of_node)
 		return;
 
 	for_each_available_child_of_node(master->dev.of_node, nc) {
-		/* Alloc an spi_device */
-		spi = spi_alloc_device(master);
-		if (!spi) {
-			dev_err(&master->dev, "spi_device alloc error for %s\n",
+		spi = of_register_spi_device(master, nc);
+		if (IS_ERR(spi))
+			dev_warn(&master->dev, "Failed to create SPI device for %s\n",
 				nc->full_name);
-			spi_dev_put(spi);
-			continue;
-		}
+	}
+}
 
-		/* Select device driver */
-		if (of_modalias_node(nc, spi->modalias,
-				     sizeof(spi->modalias)) < 0) {
-			dev_err(&master->dev, "cannot find modalias for %s\n",
-				nc->full_name);
-			spi_dev_put(spi);
-			continue;
-		}
+static int of_dev_node_match(struct device *dev, void *data)
+{
+	return dev->of_node == data;
+}
 
-		/* Device address */
-		rc = of_property_read_u32(nc, "reg", &value);
-		if (rc) {
-			dev_err(&master->dev, "%s has no valid 'reg' property (%d)\n",
-				nc->full_name, rc);
-			spi_dev_put(spi);
-			continue;
-		}
-		spi->chip_select = value;
-
-		/* Mode (clock phase/polarity/etc.) */
-		if (of_find_property(nc, "spi-cpha", NULL))
-			spi->mode |= SPI_CPHA;
-		if (of_find_property(nc, "spi-cpol", NULL))
-			spi->mode |= SPI_CPOL;
-		if (of_find_property(nc, "spi-cs-high", NULL))
-			spi->mode |= SPI_CS_HIGH;
-		if (of_find_property(nc, "spi-3wire", NULL))
-			spi->mode |= SPI_3WIRE;
-		if (of_find_property(nc, "spi-lsb-first", NULL))
-			spi->mode |= SPI_LSB_FIRST;
-
-		/* Device DUAL/QUAD mode */
-		if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
-			switch (value) {
-			case 1:
-				break;
-			case 2:
-				spi->mode |= SPI_TX_DUAL;
-				break;
-			case 4:
-				spi->mode |= SPI_TX_QUAD;
-				break;
-			default:
-				dev_warn(&master->dev,
-					 "spi-tx-bus-width %d not supported\n",
-					 value);
-				break;
-			}
-		}
+/* bah; the match functions differ just by const-ness */
+static int of_dev_node_match_const(struct device *dev, const void *data)
+{
+	return dev->of_node == data;
+}
 
-		if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
-			switch (value) {
-			case 1:
-				break;
-			case 2:
-				spi->mode |= SPI_RX_DUAL;
-				break;
-			case 4:
-				spi->mode |= SPI_RX_QUAD;
-				break;
-			default:
-				dev_warn(&master->dev,
-					 "spi-rx-bus-width %d not supported\n",
-					 value);
-				break;
-			}
-		}
+/* must call put_device() when done with returned spi_device device */
+struct spi_device *of_find_spi_device_by_node(struct device_node *node)
+{
+	struct device *dev;
 
-		/* Device speed */
-		rc = of_property_read_u32(nc, "spi-max-frequency", &value);
-		if (rc) {
-			dev_err(&master->dev, "%s has no valid 'spi-max-frequency' property (%d)\n",
-				nc->full_name, rc);
-			spi_dev_put(spi);
-			continue;
-		}
-		spi->max_speed_hz = value;
+	dev = bus_find_device(&spi_bus_type, NULL, node,
+					 of_dev_node_match);
+	if (!dev)
+		return NULL;
 
-		/* IRQ */
-		spi->irq = irq_of_parse_and_map(nc, 0);
+	return to_spi_device(dev);
+}
+EXPORT_SYMBOL(of_find_spi_device_by_node);
 
-		/* Store a pointer to the node in the device structure */
-		of_node_get(nc);
-		spi->dev.of_node = nc;
+/* forward decl */
+static struct class spi_master_class;
 
-		/* Register the new device */
-		request_module("%s%s", SPI_MODULE_PREFIX, spi->modalias);
-		rc = spi_add_device(spi);
-		if (rc) {
-			dev_err(&master->dev, "spi_device register error %s\n",
-				nc->full_name);
-			spi_dev_put(spi);
-		}
+/* the spi masters are not using spi_bus, so we find it with another way */
+struct spi_master *of_find_spi_master_by_node(struct device_node *node)
+{
+	struct device *dev;
 
-	}
+	dev = class_find_device(&spi_master_class, NULL, node,
+				of_dev_node_match_const);
+	if (!dev)
+		return NULL;
+
+	/* reference got in class_find_device */
+	return container_of(dev, struct spi_master, dev);
 }
+EXPORT_SYMBOL(of_find_spi_master_by_node);
+
 #else
 static void of_register_spi_devices(struct spi_master *master) { }
 #endif
-- 
1.7.12

Re: [PATCH v8 7/8] of: spi: Export single device registration method and accessors

[Alexander Sverdlin]

Hello Pantelis,

I've pointed to this already, but anyway:

On 28/10/14 21:36, ext Pantelis Antoniou wrote:
> Dynamically inserting spi device nodes requires the use of a single
> device registration method. Rework and export it.
> 
> Methods to lookup a device/master using a device node are added
> as well, of_find_spi_master_by_node() & of_find_spi_device_by_node().
> 
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
> ---
>  drivers/spi/spi.c | 256 +++++++++++++++++++++++++++++++++---------------------
>  1 file changed, 158 insertions(+), 98 deletions(-)
> 
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index ebcb33d..f81d799 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -1220,6 +1220,123 @@ err_init_queue:
>  /*-------------------------------------------------------------------------*/
>  
>  #if defined(CONFIG_OF)
> +
> +static struct spi_device *
> +of_register_spi_device(struct spi_master *master, struct device_node *node)

During the test Wladislav has found that node is actually not used,

> +{
> +	struct spi_device *spi;
> +	struct device_node *nc;

but non-initialized nc is used further in the code.
Should not nc be a parameter of the function instead of a local variable?

> +	int rc;
> +	u32 value;
> +
> +	/* Alloc an spi_device */
> +	spi = spi_alloc_device(master);
> +	if (!spi) {
> +		dev_err(&master->dev, "spi_device alloc error for %s\n",
> +			nc->full_name);
> +		rc = -ENOMEM;
> +		goto err_out;
> +	}
> +
> +	/* Select device driver */
> +	rc = of_modalias_node(nc, spi->modalias,
> +				sizeof(spi->modalias));
> +	if (rc < 0) {
> +		dev_err(&master->dev, "cannot find modalias for %s\n",
> +			nc->full_name);
> +		goto err_out;
> +	}
> +
> +	/* Device address */
> +	rc = of_property_read_u32(nc, "reg", &value);
> +	if (rc) {
> +		dev_err(&master->dev, "%s has no valid 'reg' property (%d)\n",
> +			nc->full_name, rc);
> +		goto err_out;
> +	}
> +	spi->chip_select = value;
> +
> +	/* Mode (clock phase/polarity/etc.) */
> +	if (of_find_property(nc, "spi-cpha", NULL))
> +		spi->mode |= SPI_CPHA;
> +	if (of_find_property(nc, "spi-cpol", NULL))
> +		spi->mode |= SPI_CPOL;
> +	if (of_find_property(nc, "spi-cs-high", NULL))
> +		spi->mode |= SPI_CS_HIGH;
> +	if (of_find_property(nc, "spi-3wire", NULL))
> +		spi->mode |= SPI_3WIRE;
> +	if (of_find_property(nc, "spi-lsb-first", NULL))
> +		spi->mode |= SPI_LSB_FIRST;
> +
> +	/* Device DUAL/QUAD mode */
> +	if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
> +		switch (value) {
> +		case 1:
> +			break;
> +		case 2:
> +			spi->mode |= SPI_TX_DUAL;
> +			break;
> +		case 4:
> +			spi->mode |= SPI_TX_QUAD;
> +			break;
> +		default:
> +			dev_warn(&master->dev,
> +				"spi-tx-bus-width %d not supported\n",
> +				value);
> +			break;
> +		}
> +	}
> +
> +	if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
> +		switch (value) {
> +		case 1:
> +			break;
> +		case 2:
> +			spi->mode |= SPI_RX_DUAL;
> +			break;
> +		case 4:
> +			spi->mode |= SPI_RX_QUAD;
> +			break;
> +		default:
> +			dev_warn(&master->dev,
> +				"spi-rx-bus-width %d not supported\n",
> +				value);
> +			break;
> +		}
> +	}
> +
> +	/* Device speed */
> +	rc = of_property_read_u32(nc, "spi-max-frequency", &value);
> +	if (rc) {
> +		dev_err(&master->dev, "%s has no valid 'spi-max-frequency' property (%d)\n",
> +			nc->full_name, rc);
> +		goto err_out;
> +	}
> +	spi->max_speed_hz = value;
> +
> +	/* IRQ */
> +	spi->irq = irq_of_parse_and_map(nc, 0);
> +
> +	/* Store a pointer to the node in the device structure */
> +	of_node_get(nc);
> +	spi->dev.of_node = nc;
> +
> +	/* Register the new device */
> +	request_module("%s%s", SPI_MODULE_PREFIX, spi->modalias);
> +	rc = spi_add_device(spi);
> +	if (rc) {
> +		dev_err(&master->dev, "spi_device register error %s\n",
> +			nc->full_name);
> +		goto err_out;
> +	}
> +
> +	return spi;
> +
> +err_out:
> +	spi_dev_put(spi);
> +	return ERR_PTR(rc);
> +}
> +
>  /**
>   * of_register_spi_devices() - Register child devices onto the SPI bus
>   * @master:	Pointer to spi_master device
> @@ -1229,120 +1346,63 @@ err_init_queue:
>   */
>  static void of_register_spi_devices(struct spi_master *master)
>  {
> -	struct spi_device *spi;
>  	struct device_node *nc;
> -	int rc;
> -	u32 value;
> +	struct spi_device *spi;
>  
>  	if (!master->dev.of_node)
>  		return;
>  
>  	for_each_available_child_of_node(master->dev.of_node, nc) {
> -		/* Alloc an spi_device */
> -		spi = spi_alloc_device(master);
> -		if (!spi) {
> -			dev_err(&master->dev, "spi_device alloc error for %s\n",
> +		spi = of_register_spi_device(master, nc);
> +		if (IS_ERR(spi))
> +			dev_warn(&master->dev, "Failed to create SPI device for %s\n",
>  				nc->full_name);
> -			spi_dev_put(spi);
> -			continue;
> -		}
> +	}
> +}
>  
> -		/* Select device driver */
> -		if (of_modalias_node(nc, spi->modalias,
> -				     sizeof(spi->modalias)) < 0) {
> -			dev_err(&master->dev, "cannot find modalias for %s\n",
> -				nc->full_name);
> -			spi_dev_put(spi);
> -			continue;
> -		}
> +static int of_dev_node_match(struct device *dev, void *data)
> +{
> +	return dev->of_node == data;
> +}
>  
> -		/* Device address */
> -		rc = of_property_read_u32(nc, "reg", &value);
> -		if (rc) {
> -			dev_err(&master->dev, "%s has no valid 'reg' property (%d)\n",
> -				nc->full_name, rc);
> -			spi_dev_put(spi);
> -			continue;
> -		}
> -		spi->chip_select = value;
> -
> -		/* Mode (clock phase/polarity/etc.) */
> -		if (of_find_property(nc, "spi-cpha", NULL))
> -			spi->mode |= SPI_CPHA;
> -		if (of_find_property(nc, "spi-cpol", NULL))
> -			spi->mode |= SPI_CPOL;
> -		if (of_find_property(nc, "spi-cs-high", NULL))
> -			spi->mode |= SPI_CS_HIGH;
> -		if (of_find_property(nc, "spi-3wire", NULL))
> -			spi->mode |= SPI_3WIRE;
> -		if (of_find_property(nc, "spi-lsb-first", NULL))
> -			spi->mode |= SPI_LSB_FIRST;
> -
> -		/* Device DUAL/QUAD mode */
> -		if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
> -			switch (value) {
> -			case 1:
> -				break;
> -			case 2:
> -				spi->mode |= SPI_TX_DUAL;
> -				break;
> -			case 4:
> -				spi->mode |= SPI_TX_QUAD;
> -				break;
> -			default:
> -				dev_warn(&master->dev,
> -					 "spi-tx-bus-width %d not supported\n",
> -					 value);
> -				break;
> -			}
> -		}
> +/* bah; the match functions differ just by const-ness */
> +static int of_dev_node_match_const(struct device *dev, const void *data)
> +{
> +	return dev->of_node == data;
> +}
>  
> -		if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
> -			switch (value) {
> -			case 1:
> -				break;
> -			case 2:
> -				spi->mode |= SPI_RX_DUAL;
> -				break;
> -			case 4:
> -				spi->mode |= SPI_RX_QUAD;
> -				break;
> -			default:
> -				dev_warn(&master->dev,
> -					 "spi-rx-bus-width %d not supported\n",
> -					 value);
> -				break;
> -			}
> -		}
> +/* must call put_device() when done with returned spi_device device */
> +struct spi_device *of_find_spi_device_by_node(struct device_node *node)
> +{
> +	struct device *dev;
>  
> -		/* Device speed */
> -		rc = of_property_read_u32(nc, "spi-max-frequency", &value);
> -		if (rc) {
> -			dev_err(&master->dev, "%s has no valid 'spi-max-frequency' property (%d)\n",
> -				nc->full_name, rc);
> -			spi_dev_put(spi);
> -			continue;
> -		}
> -		spi->max_speed_hz = value;
> +	dev = bus_find_device(&spi_bus_type, NULL, node,
> +					 of_dev_node_match);
> +	if (!dev)
> +		return NULL;
>  
> -		/* IRQ */
> -		spi->irq = irq_of_parse_and_map(nc, 0);
> +	return to_spi_device(dev);
> +}
> +EXPORT_SYMBOL(of_find_spi_device_by_node);
>  
> -		/* Store a pointer to the node in the device structure */
> -		of_node_get(nc);
> -		spi->dev.of_node = nc;
> +/* forward decl */
> +static struct class spi_master_class;
>  
> -		/* Register the new device */
> -		request_module("%s%s", SPI_MODULE_PREFIX, spi->modalias);
> -		rc = spi_add_device(spi);
> -		if (rc) {
> -			dev_err(&master->dev, "spi_device register error %s\n",
> -				nc->full_name);
> -			spi_dev_put(spi);
> -		}
> +/* the spi masters are not using spi_bus, so we find it with another way */
> +struct spi_master *of_find_spi_master_by_node(struct device_node *node)
> +{
> +	struct device *dev;
>  
> -	}
> +	dev = class_find_device(&spi_master_class, NULL, node,
> +				of_dev_node_match_const);
> +	if (!dev)
> +		return NULL;
> +
> +	/* reference got in class_find_device */
> +	return container_of(dev, struct spi_master, dev);
>  }
> +EXPORT_SYMBOL(of_find_spi_master_by_node);
> +
>  #else
>  static void of_register_spi_devices(struct spi_master *master) { }
>  #endif
> 

-- 
Best regards,
Alexander Sverdlin.

Re: [PATCH v8 7/8] of: spi: Export single device registration method and accessors

[Pantelis Antoniou]

Hi Alexander,

> On Oct 29, 2014, at 09:44 , Alexander Sverdlin <alexander.sverdlin@nsn.com> wrote:
> 
> Hello Pantelis,
> 
> I've pointed to this already, but anyway:
> 
> On 28/10/14 21:36, ext Pantelis Antoniou wrote:
>> Dynamically inserting spi device nodes requires the use of a single
>> device registration method. Rework and export it.
>> 
>> Methods to lookup a device/master using a device node are added
>> as well, of_find_spi_master_by_node() & of_find_spi_device_by_node().
>> 
>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
>> ---
>> drivers/spi/spi.c | 256 +++++++++++++++++++++++++++++++++---------------------
>> 1 file changed, 158 insertions(+), 98 deletions(-)
>> 
>> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
>> index ebcb33d..f81d799 100644
>> --- a/drivers/spi/spi.c
>> +++ b/drivers/spi/spi.c
>> @@ -1220,6 +1220,123 @@ err_init_queue:
>> /*-------------------------------------------------------------------------*/
>> 
>> #if defined(CONFIG_OF)
>> +
>> +static struct spi_device *
>> +of_register_spi_device(struct spi_master *master, struct device_node *node)
> 
> During the test Wladislav has found that node is actually not used,
> 

Ugh.

>> +{
>> +	struct spi_device *spi;
>> +	struct device_node *nc;
> 
> but non-initialized nc is used further in the code.
> Should not nc be a parameter of the function instead of a local variable?
> 

Yes, my mistake. Updated patch follows.

>> +	int rc;
>> +	u32 value;
>> +
>> +	/* Alloc an spi_device */
>> +	spi = spi_alloc_device(master);
>> +	if (!spi) {
>> +		dev_err(&master->dev, "spi_device alloc error for %s\n",
>> +			nc->full_name);
>> +		rc = -ENOMEM;
>> +		goto err_out;
>> +	}
>> +
>> +	/* Select device driver */
>> +	rc = of_modalias_node(nc, spi->modalias,
>> +				sizeof(spi->modalias));
>> +	if (rc < 0) {
>> +		dev_err(&master->dev, "cannot find modalias for %s\n",
>> +			nc->full_name);
>> +		goto err_out;
>> +	}
>> +
>> +	/* Device address */
>> +	rc = of_property_read_u32(nc, "reg", &value);
>> +	if (rc) {
>> +		dev_err(&master->dev, "%s has no valid 'reg' property (%d)\n",
>> +			nc->full_name, rc);
>> +		goto err_out;
>> +	}
>> +	spi->chip_select = value;
>> +
>> +	/* Mode (clock phase/polarity/etc.) */
>> +	if (of_find_property(nc, "spi-cpha", NULL))
>> +		spi->mode |= SPI_CPHA;
>> +	if (of_find_property(nc, "spi-cpol", NULL))
>> +		spi->mode |= SPI_CPOL;
>> +	if (of_find_property(nc, "spi-cs-high", NULL))
>> +		spi->mode |= SPI_CS_HIGH;
>> +	if (of_find_property(nc, "spi-3wire", NULL))
>> +		spi->mode |= SPI_3WIRE;
>> +	if (of_find_property(nc, "spi-lsb-first", NULL))
>> +		spi->mode |= SPI_LSB_FIRST;
>> +
>> +	/* Device DUAL/QUAD mode */
>> +	if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
>> +		switch (value) {
>> +		case 1:
>> +			break;
>> +		case 2:
>> +			spi->mode |= SPI_TX_DUAL;
>> +			break;
>> +		case 4:
>> +			spi->mode |= SPI_TX_QUAD;
>> +			break;
>> +		default:
>> +			dev_warn(&master->dev,
>> +				"spi-tx-bus-width %d not supported\n",
>> +				value);
>> +			break;
>> +		}
>> +	}
>> +
>> +	if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
>> +		switch (value) {
>> +		case 1:
>> +			break;
>> +		case 2:
>> +			spi->mode |= SPI_RX_DUAL;
>> +			break;
>> +		case 4:
>> +			spi->mode |= SPI_RX_QUAD;
>> +			break;
>> +		default:
>> +			dev_warn(&master->dev,
>> +				"spi-rx-bus-width %d not supported\n",
>> +				value);
>> +			break;
>> +		}
>> +	}
>> +
>> +	/* Device speed */
>> +	rc = of_property_read_u32(nc, "spi-max-frequency", &value);
>> +	if (rc) {
>> +		dev_err(&master->dev, "%s has no valid 'spi-max-frequency' property (%d)\n",
>> +			nc->full_name, rc);
>> +		goto err_out;
>> +	}
>> +	spi->max_speed_hz = value;
>> +
>> +	/* IRQ */
>> +	spi->irq = irq_of_parse_and_map(nc, 0);
>> +
>> +	/* Store a pointer to the node in the device structure */
>> +	of_node_get(nc);
>> +	spi->dev.of_node = nc;
>> +
>> +	/* Register the new device */
>> +	request_module("%s%s", SPI_MODULE_PREFIX, spi->modalias);
>> +	rc = spi_add_device(spi);
>> +	if (rc) {
>> +		dev_err(&master->dev, "spi_device register error %s\n",
>> +			nc->full_name);
>> +		goto err_out;
>> +	}
>> +
>> +	return spi;
>> +
>> +err_out:
>> +	spi_dev_put(spi);
>> +	return ERR_PTR(rc);
>> +}
>> +
>> /**
>>  * of_register_spi_devices() - Register child devices onto the SPI bus
>>  * @master:	Pointer to spi_master device
>> @@ -1229,120 +1346,63 @@ err_init_queue:
>>  */
>> static void of_register_spi_devices(struct spi_master *master)
>> {
>> -	struct spi_device *spi;
>> 	struct device_node *nc;
>> -	int rc;
>> -	u32 value;
>> +	struct spi_device *spi;
>> 
>> 	if (!master->dev.of_node)
>> 		return;
>> 
>> 	for_each_available_child_of_node(master->dev.of_node, nc) {
>> -		/* Alloc an spi_device */
>> -		spi = spi_alloc_device(master);
>> -		if (!spi) {
>> -			dev_err(&master->dev, "spi_device alloc error for %s\n",
>> +		spi = of_register_spi_device(master, nc);
>> +		if (IS_ERR(spi))
>> +			dev_warn(&master->dev, "Failed to create SPI device for %s\n",
>> 				nc->full_name);
>> -			spi_dev_put(spi);
>> -			continue;
>> -		}
>> +	}
>> +}
>> 
>> -		/* Select device driver */
>> -		if (of_modalias_node(nc, spi->modalias,
>> -				     sizeof(spi->modalias)) < 0) {
>> -			dev_err(&master->dev, "cannot find modalias for %s\n",
>> -				nc->full_name);
>> -			spi_dev_put(spi);
>> -			continue;
>> -		}
>> +static int of_dev_node_match(struct device *dev, void *data)
>> +{
>> +	return dev->of_node == data;
>> +}
>> 
>> -		/* Device address */
>> -		rc = of_property_read_u32(nc, "reg", &value);
>> -		if (rc) {
>> -			dev_err(&master->dev, "%s has no valid 'reg' property (%d)\n",
>> -				nc->full_name, rc);
>> -			spi_dev_put(spi);
>> -			continue;
>> -		}
>> -		spi->chip_select = value;
>> -
>> -		/* Mode (clock phase/polarity/etc.) */
>> -		if (of_find_property(nc, "spi-cpha", NULL))
>> -			spi->mode |= SPI_CPHA;
>> -		if (of_find_property(nc, "spi-cpol", NULL))
>> -			spi->mode |= SPI_CPOL;
>> -		if (of_find_property(nc, "spi-cs-high", NULL))
>> -			spi->mode |= SPI_CS_HIGH;
>> -		if (of_find_property(nc, "spi-3wire", NULL))
>> -			spi->mode |= SPI_3WIRE;
>> -		if (of_find_property(nc, "spi-lsb-first", NULL))
>> -			spi->mode |= SPI_LSB_FIRST;
>> -
>> -		/* Device DUAL/QUAD mode */
>> -		if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
>> -			switch (value) {
>> -			case 1:
>> -				break;
>> -			case 2:
>> -				spi->mode |= SPI_TX_DUAL;
>> -				break;
>> -			case 4:
>> -				spi->mode |= SPI_TX_QUAD;
>> -				break;
>> -			default:
>> -				dev_warn(&master->dev,
>> -					 "spi-tx-bus-width %d not supported\n",
>> -					 value);
>> -				break;
>> -			}
>> -		}
>> +/* bah; the match functions differ just by const-ness */
>> +static int of_dev_node_match_const(struct device *dev, const void *data)
>> +{
>> +	return dev->of_node == data;
>> +}
>> 
>> -		if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
>> -			switch (value) {
>> -			case 1:
>> -				break;
>> -			case 2:
>> -				spi->mode |= SPI_RX_DUAL;
>> -				break;
>> -			case 4:
>> -				spi->mode |= SPI_RX_QUAD;
>> -				break;
>> -			default:
>> -				dev_warn(&master->dev,
>> -					 "spi-rx-bus-width %d not supported\n",
>> -					 value);
>> -				break;
>> -			}
>> -		}
>> +/* must call put_device() when done with returned spi_device device */
>> +struct spi_device *of_find_spi_device_by_node(struct device_node *node)
>> +{
>> +	struct device *dev;
>> 
>> -		/* Device speed */
>> -		rc = of_property_read_u32(nc, "spi-max-frequency", &value);
>> -		if (rc) {
>> -			dev_err(&master->dev, "%s has no valid 'spi-max-frequency' property (%d)\n",
>> -				nc->full_name, rc);
>> -			spi_dev_put(spi);
>> -			continue;
>> -		}
>> -		spi->max_speed_hz = value;
>> +	dev = bus_find_device(&spi_bus_type, NULL, node,
>> +					 of_dev_node_match);
>> +	if (!dev)
>> +		return NULL;
>> 
>> -		/* IRQ */
>> -		spi->irq = irq_of_parse_and_map(nc, 0);
>> +	return to_spi_device(dev);
>> +}
>> +EXPORT_SYMBOL(of_find_spi_device_by_node);
>> 
>> -		/* Store a pointer to the node in the device structure */
>> -		of_node_get(nc);
>> -		spi->dev.of_node = nc;
>> +/* forward decl */
>> +static struct class spi_master_class;
>> 
>> -		/* Register the new device */
>> -		request_module("%s%s", SPI_MODULE_PREFIX, spi->modalias);
>> -		rc = spi_add_device(spi);
>> -		if (rc) {
>> -			dev_err(&master->dev, "spi_device register error %s\n",
>> -				nc->full_name);
>> -			spi_dev_put(spi);
>> -		}
>> +/* the spi masters are not using spi_bus, so we find it with another way */
>> +struct spi_master *of_find_spi_master_by_node(struct device_node *node)
>> +{
>> +	struct device *dev;
>> 
>> -	}
>> +	dev = class_find_device(&spi_master_class, NULL, node,
>> +				of_dev_node_match_const);
>> +	if (!dev)
>> +		return NULL;
>> +
>> +	/* reference got in class_find_device */
>> +	return container_of(dev, struct spi_master, dev);
>> }
>> +EXPORT_SYMBOL(of_find_spi_master_by_node);
>> +
>> #else
>> static void of_register_spi_devices(struct spi_master *master) { }
>> #endif
>> 
> 
> -- 
> Best regards,
> Alexander Sverdlin.

Regards

— Pantelis

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[PATCH v8 8/8] OF: spi: Add OF notifier handler

[Pantelis Antoniou]

Add OF notifier handler needed for creating/destroying spi devices
according to dynamic runtime changes in the DT live tree.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
---
 drivers/spi/spi.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 77 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index f81d799..f62a3e4 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2363,6 +2363,71 @@ EXPORT_SYMBOL_GPL(spi_write_then_read);
 
 /*-------------------------------------------------------------------------*/
 
+#if IS_ENABLED(CONFIG_OF)
+
+static int of_spi_notify(struct notifier_block *nb,
+				unsigned long action, void *arg)
+{
+	struct device_node *dn;
+	struct spi_master *master;
+	struct spi_device *spi;
+	int state;
+
+	state = of_reconfig_get_state_change(action, arg);
+	if (state == -1)
+		return NOTIFY_OK;
+
+	switch (action) {
+	case OF_RECONFIG_ATTACH_NODE:
+	case OF_RECONFIG_DETACH_NODE:
+		dn = arg;
+		break;
+	case OF_RECONFIG_ADD_PROPERTY:
+	case OF_RECONFIG_REMOVE_PROPERTY:
+	case OF_RECONFIG_UPDATE_PROPERTY:
+		dn = ((struct of_prop_reconfig *)arg)->dn;
+		break;
+	default:
+		return NOTIFY_OK;
+	}
+
+	if (state) {
+
+		master = of_find_spi_master_by_node(dn->parent);
+		if (master == NULL)
+			return NOTIFY_OK;	/* not for us */
+
+		spi = of_register_spi_device(master, dn);
+		put_device(&master->dev);
+
+		if (IS_ERR(spi)) {
+			pr_err("%s: failed to create for '%s'\n",
+					__func__, dn->full_name);
+			return notifier_from_errno(PTR_ERR(spi));
+		}
+
+	} else {
+
+		/* find our device by node */
+		spi = of_find_spi_device_by_node(dn);
+		if (spi == NULL)
+			return NOTIFY_OK;	/* no? not meant for us */
+
+		/* unregister takes one ref away */
+		spi_unregister_device(spi);
+
+		/* and put the reference of the find */
+		put_device(&spi->dev);
+
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block spi_of_notifier;
+
+#endif
+
 static int __init spi_init(void)
 {
 	int	status;
@@ -2380,8 +2445,19 @@ static int __init spi_init(void)
 	status = class_register(&spi_master_class);
 	if (status < 0)
 		goto err2;
-	return 0;
 
+#if IS_ENABLED(CONFIG_OF)
+	spi_of_notifier.notifier_call = of_spi_notify;
+	status = of_reconfig_notifier_register(&spi_of_notifier);
+	if (status)
+		goto err3;
+#endif
+
+	return 0;
+#if IS_ENABLED(CONFIG_OF)
+err3:
+	class_unregister(&spi_master_class);
+#endif
 err2:
 	bus_unregister(&spi_bus_type);
 err1:
-- 
1.7.12