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Message-Id: <20250610-gpio-sysfs-chip-export-v1-6-a8c7aa4478b1@linaro.org>
Date: Tue, 10 Jun 2025 16:38:21 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Ahmad Fatoum <a.fatoum@...gutronix.de>,
Kent Gibson <warthog618@...il.com>,
Jan Lübbe <jlu@...gutronix.de>,
Marek Vasut <marex@...x.de>, Geert Uytterhoeven <geert+renesas@...der.be>,
Linus Walleij <linus.walleij@...aro.org>,
Bartosz Golaszewski <brgl@...ev.pl>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH RFC/RFT 06/15] gpio: sysfs: remove the mockdev pointer from
struct gpio_device
From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
The usage of the mockdev pointer in struct gpio_device is limited to the
GPIO sysfs code. There's no reason to keep it in this top-level
structure. Create a separate structure containing the reference to the
GPIO device and the dummy class device that will be passed to
device_create_with_groups(). The !gdev->mockdev checks can be removed as
long as we make sure that all operations on the GPIO class are protected
with the sysfs lock.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
drivers/gpio/gpiolib-sysfs.c | 81 +++++++++++++++++++++++++++++---------------
drivers/gpio/gpiolib.h | 3 --
2 files changed, 53 insertions(+), 31 deletions(-)
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index f23b4efea5905a9eab51ed9e50b5159135a8e26c..956411fc467a26a9827c616d8dc067c70f9244bf 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -43,6 +43,11 @@ struct gpiod_data {
bool direction_can_change;
};
+struct gpiodev_data {
+ struct gpio_device *gdev;
+ struct device *cdev_base; /* Class device by GPIO base */
+};
+
/*
* Lock to serialise gpiod export and unexport, and prevent re-export of
* gpiod whose chip is being unregistered.
@@ -399,27 +404,27 @@ static const struct attribute_group *gpio_groups[] = {
static ssize_t base_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
- const struct gpio_device *gdev = dev_get_drvdata(dev);
+ const struct gpiodev_data *data = dev_get_drvdata(dev);
- return sysfs_emit(buf, "%u\n", gdev->base);
+ return sysfs_emit(buf, "%u\n", data->gdev->base);
}
static DEVICE_ATTR_RO(base);
static ssize_t label_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
- const struct gpio_device *gdev = dev_get_drvdata(dev);
+ const struct gpiodev_data *data = dev_get_drvdata(dev);
- return sysfs_emit(buf, "%s\n", gdev->label);
+ return sysfs_emit(buf, "%s\n", data->gdev->label);
}
static DEVICE_ATTR_RO(label);
static ssize_t ngpio_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
- const struct gpio_device *gdev = dev_get_drvdata(dev);
+ const struct gpiodev_data *data = dev_get_drvdata(dev);
- return sysfs_emit(buf, "%u\n", gdev->ngpio);
+ return sysfs_emit(buf, "%u\n", data->gdev->ngpio);
}
static DEVICE_ATTR_RO(ngpio);
@@ -545,6 +550,26 @@ static const struct class gpio_class = {
.class_groups = gpio_class_groups,
};
+static int match_gdev(struct device *dev, const void *desc)
+{
+ struct gpiodev_data *data = dev_get_drvdata(dev);
+ const struct gpio_device *gdev = desc;
+
+ return data && data->gdev == gdev;
+}
+
+static struct gpiodev_data *
+gdev_get_data(struct gpio_device *gdev) __must_hold(&sysfs_lock)
+{
+ struct device *cdev __free(put_device) = class_find_device(&gpio_class,
+ NULL, gdev,
+ match_gdev);
+ if (!cdev)
+ return NULL;
+
+ return dev_get_drvdata(cdev);
+};
+
/**
* gpiod_export - export a GPIO through sysfs
* @desc: GPIO to make available, already requested
@@ -590,12 +615,6 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
guard(mutex)(&sysfs_lock);
- /* check if chip is being removed */
- if (!gdev->mockdev) {
- status = -ENODEV;
- goto err_clear_bit;
- }
-
if (!test_bit(FLAG_REQUESTED, &desc->flags)) {
gpiod_dbg(desc, "%s: unavailable (not requested)\n", __func__);
status = -EPERM;
@@ -719,9 +738,9 @@ EXPORT_SYMBOL_GPL(gpiod_unexport);
int gpiochip_sysfs_register(struct gpio_device *gdev)
{
+ struct gpiodev_data *data;
struct gpio_chip *chip;
struct device *parent;
- struct device *dev;
/*
* Many systems add gpio chips for SOC support very early,
@@ -747,32 +766,41 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
else
parent = &gdev->dev;
- /* use chip->base for the ID; it's already known to be unique */
- dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), gdev,
- gpiochip_groups, GPIOCHIP_NAME "%d",
- chip->base);
- if (IS_ERR(dev))
- return PTR_ERR(dev);
+ data = kmalloc(sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->gdev = gdev;
guard(mutex)(&sysfs_lock);
- gdev->mockdev = dev;
+
+ /* use chip->base for the ID; it's already known to be unique */
+ data->cdev_base = device_create_with_groups(&gpio_class, parent,
+ MKDEV(0, 0), data,
+ gpiochip_groups,
+ GPIOCHIP_NAME "%d",
+ chip->base);
+ if (IS_ERR(data->cdev_base)) {
+ kfree(data);
+ return PTR_ERR(data->cdev_base);
+ }
return 0;
}
void gpiochip_sysfs_unregister(struct gpio_device *gdev)
{
+ struct gpiodev_data *data;
struct gpio_desc *desc;
struct gpio_chip *chip;
scoped_guard(mutex, &sysfs_lock) {
- if (!gdev->mockdev)
+ data = gdev_get_data(gdev);
+ if (!data)
return;
- device_unregister(gdev->mockdev);
-
- /* prevent further gpiod exports */
- gdev->mockdev = NULL;
+ device_unregister(data->cdev_base);
+ kfree(data);
}
guard(srcu)(&gdev->srcu);
@@ -798,9 +826,6 @@ static int gpiofind_sysfs_register(struct gpio_chip *gc, const void *data)
struct gpio_device *gdev = gc->gpiodev;
int ret;
- if (gdev->mockdev)
- return 0;
-
ret = gpiochip_sysfs_register(gdev);
if (ret)
chip_err(gc, "failed to register the sysfs entry: %d\n", ret);
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 58f64056de77b05e8cbcb2395a55da793b1a52fa..9b74738a9ca5b1a4826c8d56d871f8a7cf6ea1e7 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -27,8 +27,6 @@
* @dev: the GPIO device struct
* @chrdev: character device for the GPIO device
* @id: numerical ID number for the GPIO chip
- * @mockdev: class device used by the deprecated sysfs interface (may be
- * NULL)
* @owner: helps prevent removal of modules exporting active GPIOs
* @chip: pointer to the corresponding gpiochip, holding static
* data for this device
@@ -65,7 +63,6 @@ struct gpio_device {
struct device dev;
struct cdev chrdev;
int id;
- struct device *mockdev;
struct module *owner;
struct gpio_chip __rcu *chip;
struct gpio_desc *descs;
--
2.48.1
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