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gpio: sysfs: remove the mockdev pointer from struct gpio_device

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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.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250610-gpio-sysfs-chip-export-v1-6-a8c7aa4478b1@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Bartosz Golaszewski 2025-06-10 16:38:21 +02:00
parent 982ec96c38
commit fd19792851
2 changed files with 53 additions and 31 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

81
drivers/gpio/gpiolib-sysfs.c
View file

@ -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);

3
drivers/gpio/gpiolib.h
View file

@ -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;