From: "Rafał Miłecki" <zajec5@gmail.com>
To: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Jonathan Corbet <corbet@lwn.net>
Cc: "Daniel Vetter" <daniel.vetter@ffwll.ch>,
"Dan Williams" <dan.j.williams@intel.com>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Heiner Kallweit" <hkallweit1@gmail.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
"Rafał Miłecki" <rafal@milecki.pl>
Subject: [PATCH 2/2] nvmem: expose NVMEM cells in sysfs
Date: Mon, 20 Dec 2021 07:47:30 +0100 [thread overview]
Message-ID: <20211220064730.28806-2-zajec5@gmail.com> (raw)
In-Reply-To: <20211220064730.28806-1-zajec5@gmail.com>
From: Rafał Miłecki <rafal@milecki.pl>
This allows reading NVMEM cells using /sys/bus/nvmem/devices/*/cells/*
which may be helpful for userspace & debugging purposes.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
Documentation/driver-api/nvmem.rst | 11 ++++++
drivers/nvmem/core.c | 60 ++++++++++++++++++++++++++++++
2 files changed, 71 insertions(+)
diff --git a/Documentation/driver-api/nvmem.rst b/Documentation/driver-api/nvmem.rst
index 287e86819640..20f7d68143be 100644
--- a/Documentation/driver-api/nvmem.rst
+++ b/Documentation/driver-api/nvmem.rst
@@ -185,6 +185,17 @@ ex::
*
0001000
+Single cells can be read using files located at::
+
+ /sys/bus/nvmem/devices/*/cells/*
+
+ex::
+
+ hexdump -C /sys/bus/nvmem/devices/mtd0/cells/mac
+
+ 00000000 10 7b 44 c4 8a b0 |.{D...|
+ 00000006
+
7. DeviceTree Binding
=====================
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 23a38dcf0fc4..785a56e33f69 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -55,6 +55,7 @@ struct nvmem_cell_entry {
struct device_node *np;
struct nvmem_device *nvmem;
struct list_head node;
+ struct bin_attribute battr;
};
struct nvmem_cell {
@@ -73,6 +74,10 @@ static LIST_HEAD(nvmem_lookup_list);
static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
+static int __nvmem_cell_read(struct nvmem_device *nvmem,
+ struct nvmem_cell_entry *cell,
+ void *buf, size_t *len, const char *id);
+
static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
void *val, size_t bytes)
{
@@ -338,8 +343,18 @@ static const struct attribute_group nvmem_bin_group = {
.is_bin_visible = nvmem_bin_attr_is_visible,
};
+static struct bin_attribute *nvmem_cells_bin_attrs[] = {
+ NULL,
+};
+
+static const struct attribute_group nvmem_cells_group = {
+ .name = "cells",
+ .bin_attrs = nvmem_cells_bin_attrs,
+};
+
static const struct attribute_group *nvmem_dev_groups[] = {
&nvmem_bin_group,
+ &nvmem_cells_group,
NULL,
};
@@ -431,7 +446,13 @@ static struct bus_type nvmem_bus_type = {
static void nvmem_cell_entry_drop(struct nvmem_cell_entry *cell)
{
+ struct device *dev = &cell->nvmem->dev;
+
blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_REMOVE, cell);
+
+ sysfs_remove_file_from_group(&dev->kobj, &cell->battr.attr,
+ nvmem_cells_group.name);
+
mutex_lock(&nvmem_mutex);
list_del(&cell->node);
mutex_unlock(&nvmem_mutex);
@@ -448,11 +469,50 @@ static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
nvmem_cell_entry_drop(cell);
}
+static ssize_t nvmem_cell_attr_read(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *battr, char *buf,
+ loff_t pos, size_t count)
+{
+ struct nvmem_cell_entry *cell = container_of(battr, struct nvmem_cell_entry, battr);
+ struct nvmem_device *nvmem = cell->nvmem;
+ size_t bytes;
+ u8 *data;
+ int err;
+
+ if (pos >= cell->bytes)
+ return 0;
+
+ data = kzalloc(cell->bytes, GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ err = __nvmem_cell_read(nvmem, cell, data, &bytes, NULL);
+ if (!err)
+ memcpy(buf, data + pos, count - pos);
+
+ kfree(data);
+
+ return err ? err : bytes;
+}
+
static void nvmem_cell_entry_add(struct nvmem_cell_entry *cell)
{
+ struct device *dev = &cell->nvmem->dev;
+ int err;
+
mutex_lock(&nvmem_mutex);
list_add_tail(&cell->node, &cell->nvmem->cells);
mutex_unlock(&nvmem_mutex);
+
+ sysfs_attr_init(&cell->battr.attr);
+ cell->battr.attr.name = cell->name;
+ cell->battr.attr.mode = 0400;
+ cell->battr.read = nvmem_cell_attr_read;
+ err = sysfs_add_bin_file_to_group(&dev->kobj, &cell->battr,
+ nvmem_cells_group.name);
+ if (err)
+ dev_warn(dev, "Failed to add %s cell: %d\n", cell->name, err);
+
blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
}
--
2.31.1
next prev parent reply other threads:[~2021-12-20 6:48 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-20 6:47 [PATCH 1/2] sysfs: add sysfs_add_bin_file_to_group() Rafał Miłecki
2021-12-20 6:47 ` Rafał Miłecki [this message]
2021-12-20 8:00 ` [PATCH 2/2] nvmem: expose NVMEM cells in sysfs Greg Kroah-Hartman
2021-12-20 20:39 ` Rafał Miłecki
2021-12-21 6:33 ` Greg Kroah-Hartman
2021-12-21 6:39 ` Rafał Miłecki
2021-12-21 6:45 ` Greg Kroah-Hartman
2021-12-21 6:53 ` Rafał Miłecki
2021-12-21 7:13 ` Greg Kroah-Hartman
2021-12-21 12:24 ` Rafał Miłecki
2021-12-21 12:56 ` Greg Kroah-Hartman
2021-12-21 13:05 ` Rafał Miłecki
2021-12-21 13:27 ` Greg Kroah-Hartman
2021-12-21 13:52 ` Rafał Miłecki
2021-12-21 14:27 ` Greg Kroah-Hartman
2021-12-21 15:09 ` Rafał Miłecki
2021-12-21 15:18 ` Greg Kroah-Hartman
2021-12-21 15:33 ` Rafał Miłecki
2021-12-22 0:11 ` John Thomson
2021-12-20 8:01 ` [PATCH 1/2] sysfs: add sysfs_add_bin_file_to_group() Greg Kroah-Hartman
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