[PATCH v2 03/12] drm: rcar-du: Fix legacy DT to create LVDS encoder nodes

[Laurent Pinchart <laurent.pinchart+renesas-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>]

The internal LVDS encoders now have their own DT bindings. Before
switching the driver infrastructure to those new bindings, implement
backward-compatibility through live DT patching.

Patching is disabled and will be enabled along with support for the new
DT bindings in the DU driver.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
---
Changes since v1:

- Select OF_FLATTREE
- Compile LVDS DT bindings patch code when DRM_RCAR_LVDS is selected
- Update the SPDX headers to use GPL-2.0 instead of GPL-2.0-only
- Turn __dtb_rcar_du_of_lvds_(begin|end) from u8 to char
- Pass void begin and end pointers to rcar_du_of_get_overlay()
- Use of_get_parent() instead of accessing the parent pointer directly
- Find the LVDS endpoints nodes based on the LVDS node instead of the
  root of the overlay
- Update to the <soc>-lvds compatible string format
---
 drivers/gpu/drm/rcar-du/Kconfig             |   2 +
 drivers/gpu/drm/rcar-du/Makefile            |   3 +-
 drivers/gpu/drm/rcar-du/rcar_du_of.c        | 451 ++++++++++++++++++++++++++++
 drivers/gpu/drm/rcar-du/rcar_du_of.h        |  16 +
 drivers/gpu/drm/rcar-du/rcar_du_of_lvds.dts |  82 +++++
 5 files changed, 553 insertions(+), 1 deletion(-)
 create mode 100644 drivers/gpu/drm/rcar-du/rcar_du_of.c
 create mode 100644 drivers/gpu/drm/rcar-du/rcar_du_of.h
 create mode 100644 drivers/gpu/drm/rcar-du/rcar_du_of_lvds.dts

diff --git a/drivers/gpu/drm/rcar-du/Kconfig b/drivers/gpu/drm/rcar-du/Kconfig
index 5d0b4b7119af..3f83352a7313 100644
--- a/drivers/gpu/drm/rcar-du/Kconfig
+++ b/drivers/gpu/drm/rcar-du/Kconfig
@@ -22,6 +22,8 @@ config DRM_RCAR_LVDS
 	bool "R-Car DU LVDS Encoder Support"
 	depends on DRM_RCAR_DU
 	select DRM_PANEL
+	select OF_FLATTREE
+	select OF_OVERLAY
 	help
 	  Enable support for the R-Car Display Unit embedded LVDS encoders.
 
diff --git a/drivers/gpu/drm/rcar-du/Makefile b/drivers/gpu/drm/rcar-du/Makefile
index 0cf5c11030e8..8ed569a0f462 100644
--- a/drivers/gpu/drm/rcar-du/Makefile
+++ b/drivers/gpu/drm/rcar-du/Makefile
@@ -5,10 +5,11 @@ rcar-du-drm-y := rcar_du_crtc.o \
 		 rcar_du_group.o \
 		 rcar_du_kms.o \
 		 rcar_du_lvdscon.o \
+		 rcar_du_of.o \
 		 rcar_du_plane.o
 
 rcar-du-drm-$(CONFIG_DRM_RCAR_LVDS)	+= rcar_du_lvdsenc.o
-
+rcar-du-drm-$(CONFIG_DRM_RCAR_LVDS)	+= rcar_du_of_lvds.dtb.o
 rcar-du-drm-$(CONFIG_DRM_RCAR_VSP)	+= rcar_du_vsp.o
 
 obj-$(CONFIG_DRM_RCAR_DU)		+= rcar-du-drm.o
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_of.c b/drivers/gpu/drm/rcar-du/rcar_du_of.c
new file mode 100644
index 000000000000..2bf91201fc93
--- /dev/null
+++ b/drivers/gpu/drm/rcar-du/rcar_du_of.c
@@ -0,0 +1,451 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * rcar_du_of.c - Legacy DT bindings compatibility
+ *
+ * Copyright (C) 2018 Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
+ *
+ * Based on work from Jyri Sarha <jsarha-l0cyMroinI0@public.gmane.org>
+ * Copyright (C) 2015 Texas Instruments
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_fdt.h>
+#include <linux/of_graph.h>
+#include <linux/slab.h>
+
+#include "rcar_du_crtc.h"
+#include "rcar_du_drv.h"
+
+#ifdef CONFIG_DRM_RCAR_LVDS
+
+struct rcar_du_of_overlay {
+	struct device_node *np;
+	void *data;
+	void *mem;
+};
+
+static void __init rcar_du_of_free_overlay(struct rcar_du_of_overlay *overlay)
+{
+	of_node_put(overlay->np);
+	kfree(overlay->data);
+	kfree(overlay->mem);
+}
+
+static int __init rcar_du_of_get_overlay(struct rcar_du_of_overlay *overlay,
+					 void *begin, void *end)
+{
+	const size_t size = end - begin;
+
+	memset(overlay, 0, sizeof(*overlay));
+
+	if (!size)
+		return -EINVAL;
+
+	overlay->data = kmemdup(begin, size, GFP_KERNEL);
+	if (!overlay->data)
+		return -ENOMEM;
+
+	overlay->mem = of_fdt_unflatten_tree(overlay->data, NULL, &overlay->np);
+	if (!overlay->mem) {
+		rcar_du_of_free_overlay(overlay);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static struct device_node __init *
+rcar_du_of_find_node_by_path(struct device_node *parent, const char *path)
+{
+	parent = of_node_get(parent);
+	if (!parent)
+		return NULL;
+
+	while (parent && *path == '/') {
+		struct device_node *child = NULL;
+		struct device_node *node;
+		const char *next;
+		size_t len;
+
+		/* Skip the initial '/' delimiter and find the next one. */
+		path++;
+		next = strchrnul(path, '/');
+		len = next - path;
+		if (!len)
+			goto error;
+
+		for_each_child_of_node(parent, node) {
+			const char *name = kbasename(node->full_name);
+
+			if (strncmp(path, name, len) == 0 &&
+			    strlen(name) == len) {
+				child = node;
+				break;
+			}
+		}
+
+		if (!child)
+			goto error;
+
+		of_node_put(parent);
+		parent = child;
+		path = next;
+	}
+
+	return parent;
+
+error:
+	of_node_put(parent);
+	return NULL;
+}
+
+static int __init rcar_du_of_add_property(struct device_node *np,
+					  const char *name, const void *value,
+					  size_t length)
+{
+	struct property *prop;
+
+	prop = kzalloc(sizeof(*prop), GFP_KERNEL);
+	if (!prop)
+		return -ENOMEM;
+
+	prop->name = kstrdup(name, GFP_KERNEL);
+	prop->value = kmemdup(value, length, GFP_KERNEL);
+	prop->length = length;
+
+	if (!prop->name || !prop->value) {
+		kfree(prop->name);
+		kfree(prop->value);
+		kfree(prop);
+		return -ENOMEM;
+	}
+
+	of_property_set_flag(prop, OF_DYNAMIC);
+
+	prop->next = np->properties;
+	np->properties = prop;
+
+	return 0;
+}
+
+/* Free properties allocated dynamically by rcar_du_of_add_property(). */
+static void __init rcar_du_of_free_properties(struct device_node *np)
+{
+	while (np->properties) {
+		struct property *prop = np->properties;
+
+		np->properties = prop->next;
+
+		if (OF_IS_DYNAMIC(prop)) {
+			kfree(prop->name);
+			kfree(prop->value);
+			kfree(prop);
+		}
+	}
+}
+
+static int __init rcar_du_of_update_target_path(struct device_node *du,
+						struct device_node *remote,
+						struct device_node *np)
+{
+	struct device_node *target = NULL;
+	struct property **prev;
+	struct property *prop;
+	char *path;
+	int ret;
+
+	for (prop = np->properties, prev = &prop; prop != NULL;
+	     prev = &prop->next, prop = prop->next) {
+		if (of_prop_cmp(prop->name, "target-path"))
+			continue;
+
+		if (!of_prop_cmp(prop->value, "soc")) {
+			target = of_get_parent(du);
+			break;
+		}
+		if (!of_prop_cmp(prop->value, "du")) {
+			target = of_node_get(du);
+			break;
+		}
+		if (!of_prop_cmp(prop->value, "lvds-sink")) {
+			target = of_graph_get_port_parent(remote);
+			break;
+		}
+
+		return -EINVAL;
+	}
+
+	if (!target)
+		return -EINVAL;
+
+	path = kasprintf(GFP_KERNEL, "%pOF", target);
+	of_node_put(target);
+	if (!path)
+		return -ENOMEM;
+
+	/*
+	 * Remove the existing target-path property that has not been
+	 * dynamically allocated and replace it with a new dynamic one to
+	 * ensure that the value will be properly freed.
+	 */
+	*prev = prop->next;
+	ret = rcar_du_of_add_property(np, "target-path", path,
+				      strlen(path) + 1);
+	if (ret < 0) {
+		kfree(path);
+		return ret;
+	}
+
+	return 0;
+}
+
+extern char __dtb_rcar_du_of_lvds_begin[];
+extern char __dtb_rcar_du_of_lvds_end[];
+
+static void __init rcar_du_of_lvds_patch_one(struct device_node *du,
+					     unsigned int port_id,
+					     const struct resource *res,
+					     const __be32 *reg,
+					     const struct of_phandle_args *clkspec,
+					     struct device_node *local,
+					     struct device_node *remote)
+{
+	struct rcar_du_of_overlay overlay;
+	struct device_node *du_port_fixup;
+	struct device_node *du_port;
+	struct device_node *lvds_endpoints[2];
+	struct device_node *lvds;
+	struct device_node *fragment;
+	struct device_node *bus;
+	struct property *prop;
+	const char *compatible;
+	const char *soc_suffix;
+	unsigned int psize;
+	unsigned int i;
+	__be32 value[4];
+	char name[23];
+	int ovcs_id;
+	int ret;
+
+	/* Skip if the LVDS node already exists. */
+	sprintf(name, "lvds@%llx", (u64)res->start);
+	bus = of_get_parent(du);
+	lvds = of_get_child_by_name(bus, name);
+	of_node_put(bus);
+	if (lvds) {
+		of_node_put(lvds);
+		return;
+	}
+
+	/* Parse the overlay. */
+	ret = rcar_du_of_get_overlay(&overlay, __dtb_rcar_du_of_lvds_begin,
+				     __dtb_rcar_du_of_lvds_end);
+	if (ret < 0)
+		return;
+
+	/*
+	 * Patch the LVDS and DU port nodes names and the associated fixup
+	 * entries.
+	 */
+	lvds = rcar_du_of_find_node_by_path(overlay.np,
+		"/fragment@0/__overlay__/lvds");
+	lvds_endpoints[0] = rcar_du_of_find_node_by_path(lvds,
+		"/ports/port@0/endpoint");
+	lvds_endpoints[1] = rcar_du_of_find_node_by_path(lvds,
+		"/ports/port@1/endpoint");
+	du_port = rcar_du_of_find_node_by_path(overlay.np,
+		"/fragment@1/__overlay__/ports/port@0");
+	du_port_fixup = rcar_du_of_find_node_by_path(overlay.np,
+		"/__local_fixups__/fragment@1/__overlay__/ports/port@0");
+	if (!lvds || !lvds_endpoints[0] || !lvds_endpoints[1] ||
+	    !du_port || !du_port_fixup)
+		goto out_put_nodes;
+
+	lvds->full_name = kstrdup(name, GFP_KERNEL);
+
+	sprintf(name, "port@%u", port_id);
+	du_port->full_name = kstrdup(name, GFP_KERNEL);
+	du_port_fixup->full_name = kstrdup(name, GFP_KERNEL);
+
+	if (!lvds->full_name || !du_port->full_name ||
+	    !du_port_fixup->full_name)
+		goto out_free_names;
+
+	/* Patch the target paths in all fragments. */
+	for_each_child_of_node(overlay.np, fragment) {
+		if (strncmp("fragment@", of_node_full_name(fragment), 9))
+			continue;
+
+		ret = rcar_du_of_update_target_path(du, remote, fragment);
+		if (ret < 0) {
+			of_node_put(fragment);
+			goto out_free_properties;
+		}
+	}
+
+	/*
+	 * Create a compatible string for the LVDS node using the SoC model
+	 * from the DU node.
+	 */
+	ret = of_property_read_string(du, "compatible", &compatible);
+	if (ret < 0)
+		goto out_free_properties;
+
+	soc_suffix = strchr(compatible, '-');
+	if (!soc_suffix || strlen(soc_suffix) > 10)
+		goto out_free_properties;
+
+	psize = sprintf(name, "renesas,%s-lvds", soc_suffix + 1) + 1;
+	ret = rcar_du_of_add_property(lvds, "compatible", name, psize);
+	if (ret < 0)
+		goto out_free_properties;
+
+	/* Copy the LVDS reg and clocks properties from the DU node. */
+	psize = (of_n_addr_cells(du) + of_n_size_cells(du)) * 4;
+	ret = rcar_du_of_add_property(lvds, "reg", reg, psize);
+	if (ret < 0)
+		goto out_free_properties;
+
+	if (clkspec->args_count >= ARRAY_SIZE(value) - 1)
+		goto out_free_properties;
+
+	value[0] = cpu_to_be32(clkspec->np->phandle);
+	for (i = 0; i < clkspec->args_count; ++i)
+		value[i + 1] = cpu_to_be32(clkspec->args[i]);
+
+	psize = (clkspec->args_count + 1) * 4;
+	ret = rcar_du_of_add_property(lvds, "clocks", value, psize);
+	if (ret < 0)
+		goto out_free_properties;
+
+	/*
+	 * Insert the node in the OF graph: patch the LVDS ports remote-endpoint
+	 * properties to point to the endpoints of the sibling nodes in the
+	 * graph.
+	 */
+	prop = of_find_property(lvds_endpoints[0], "remote-endpoint", NULL);
+	if (!prop)
+		goto out_free_properties;
+
+	*(__be32 *)prop->value = cpu_to_be32(local->phandle);
+
+	prop = of_find_property(lvds_endpoints[1], "remote-endpoint", NULL);
+	if (!prop)
+		goto out_free_properties;
+
+	*(__be32 *)prop->value = cpu_to_be32(remote->phandle);
+
+	/* Apply the overlay, this will resolve phandles. */
+	ovcs_id = 0;
+	ret = of_overlay_apply(overlay.np, &ovcs_id);
+
+	/* We're done, free all allocated memory. */
+out_free_properties:
+	rcar_du_of_free_properties(lvds);
+	rcar_du_of_free_properties(du_port);
+	rcar_du_of_free_properties(du_port_fixup);
+out_free_names:
+	kfree(lvds->full_name);
+	kfree(du_port->full_name);
+	kfree(du_port_fixup->full_name);
+out_put_nodes:
+	of_node_put(lvds);
+	of_node_put(lvds_endpoints[0]);
+	of_node_put(lvds_endpoints[1]);
+	of_node_put(du_port);
+	of_node_put(du_port_fixup);
+
+	rcar_du_of_free_overlay(&overlay);
+}
+
+static void __init rcar_du_of_lvds_patch(const struct of_device_id *of_ids)
+{
+	const struct rcar_du_device_info *info;
+	const struct of_device_id *match;
+	struct device_node *du;
+	unsigned int i;
+	int ret;
+
+	/* Get the DU node and exit if not present or disabled. */
+	du = of_find_matching_node_and_match(NULL, of_ids, &match);
+	if (!du || !of_device_is_available(du))
+		goto done;
+
+	info = match->data;
+
+	/* Patch every LVDS encoder. */
+	for (i = 0; i < info->num_lvds; ++i) {
+		struct of_phandle_args clkspec;
+		struct device_node *local, *remote;
+		struct resource res;
+		unsigned int port_id;
+		const __be32 *reg;
+		char name[7];
+		int index;
+
+		/*
+		 * Retrieve the register specifier, the clock specifier and the
+		 * local and remote endpoints of the LVDS link.
+		 */
+		sprintf(name, "lvds.%u", i);
+		index = of_property_match_string(du, "reg-names", name);
+		if (index < 0)
+			continue;
+
+		reg = of_get_address(du, index, NULL, NULL);
+		if (!reg)
+			continue;
+
+		ret = of_address_to_resource(du, index, &res);
+		if (ret < 0)
+			continue;
+
+		index = of_property_match_string(du, "clock-names", name);
+		if (index < 0)
+			continue;
+
+		ret = of_parse_phandle_with_args(du, "clocks", "#clock-cells",
+						 index, &clkspec);
+		if (ret < 0)
+			continue;
+
+		port_id = info->routes[RCAR_DU_OUTPUT_LVDS0 + i].port;
+
+		local = of_graph_get_endpoint_by_regs(du, port_id, 0);
+		if (!local) {
+			of_node_put(clkspec.np);
+			continue;
+		}
+
+		remote = of_graph_get_remote_endpoint(local);
+		if (!remote) {
+			of_node_put(local);
+			of_node_put(clkspec.np);
+			continue;
+		}
+
+		/* Patch the LVDS encoder. */
+		rcar_du_of_lvds_patch_one(du, port_id, &res, reg, &clkspec,
+					  local, remote);
+
+		of_node_put(clkspec.np);
+		of_node_put(remote);
+		of_node_put(local);
+	}
+
+done:
+	of_node_put(du);
+}
+#else
+static void __init rcar_du_of_lvds_patch(const struct of_device_id *of_ids)
+{
+}
+#endif /* CONFIG_DRM_RCAR_LVDS */
+
+void __init rcar_du_of_init(const struct of_device_id *of_ids)
+{
+	rcar_du_of_lvds_patch(of_ids);
+}
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_of.h b/drivers/gpu/drm/rcar-du/rcar_du_of.h
new file mode 100644
index 000000000000..7105eaef58c6
--- /dev/null
+++ b/drivers/gpu/drm/rcar-du/rcar_du_of.h
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * rcar_du_of.h - Legacy DT bindings compatibility
+ *
+ * Copyright (C) 2018 Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
+ */
+#ifndef __RCAR_DU_OF_H__
+#define __RCAR_DU_OF_H__
+
+#include <linux/init.h>
+
+struct of_device_id;
+
+void __init rcar_du_of_init(const struct of_device_id *of_ids);
+
+#endif /* __RCAR_DU_OF_H__ */
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_of_lvds.dts b/drivers/gpu/drm/rcar-du/rcar_du_of_lvds.dts
new file mode 100644
index 000000000000..bc75c7a1c3bd
--- /dev/null
+++ b/drivers/gpu/drm/rcar-du/rcar_du_of_lvds.dts
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * rcar_du_of_lvds.dts - Legacy LVDS DT bindings conversion
+ *
+ * Copyright (C) 2018 Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
+ *
+ * Based on work from Jyri Sarha <jsarha-l0cyMroinI0@public.gmane.org>
+ * Copyright (C) 2015 Texas Instruments
+ */
+
+/*
+ * The target-paths, lvds node name, DU port number and LVDS remote endpoints
+ * will be patched dynamically at runtime.
+ */
+
+/dts-v1/;
+/ {
+	fragment@0 {
+		target-path = "soc";
+		__overlay__ {
+			lvds {
+				ports {
+					#address-cells = <1>;
+					#size-cells = <0>;
+
+					port@0 {
+						reg = <0>;
+						lvds_input: endpoint {
+							remote-endpoint = <0>;
+						};
+					};
+
+					port@1 {
+						reg = <1>;
+						lvds_output: endpoint {
+							remote-endpoint = <0>;
+						};
+					};
+				};
+			};
+		};
+	};
+
+	fragment@1 {
+		target-path = "du";
+		__overlay__ {
+			ports {
+				port@0 {
+					endpoint {
+						remote-endpoint = <&lvds_input>;
+					};
+				};
+			};
+		};
+	};
+
+	fragment@2 {
+		target-path = "lvds-sink";
+		__overlay__ {
+			remote-endpoint = <&lvds_output>;
+		};
+	};
+
+	__local_fixups__ {
+		fragment@1 {
+			__overlay__ {
+				ports {
+					port@0 {
+						endpoint {
+							remote-endpoint	= <0>;
+						};
+					};
+				};
+			};
+		};
+		fragment@2 {
+			__overlay__ {
+				remote-endpoint	= <0>;
+			};
+		};
+	};
+};
-- 
Regards,

Laurent Pinchart

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