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Message-Id: <20250610-gpio-sysfs-chip-export-v1-12-a8c7aa4478b1@linaro.org>
Date: Tue, 10 Jun 2025 16:38:27 +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 12/15] gpio: sysfs: don't look up exported lines as
class devices
From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
In preparation for adding a parallel, per-chip attribute group for
exported GPIO lines, stop using class device APIs to refer to it in the
code. When unregistering the chip, don't call class_find_device() but
instead store exported lines in a linked list inside the GPIO chip data
object and look it up there.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
drivers/gpio/gpiolib-sysfs.c | 60 ++++++++++++++++++++++++++++++++------------
1 file changed, 44 insertions(+), 16 deletions(-)
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 398cefb4be9e389a820dd53f79c82fa70783b5e0..aa998d9e96cce5d64784645eea73f987471c7285 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -43,6 +43,7 @@ enum {
struct gpiod_data {
struct gpio_desc *desc;
+ struct device *dev;
struct mutex mutex;
struct kernfs_node *value_class_node;
@@ -58,12 +59,15 @@ struct gpiod_data {
struct attribute *attrs[GPIO_SYSFS_LINE_ATTR_SIZE];
struct attribute_group attr_group;
const struct attribute_group *attr_groups[2];
+
+ struct list_head list;
};
struct gpiodev_data {
struct gpio_device *gdev;
struct device *cdev_base; /* Class device by GPIO base */
struct device *cdev_id; /* Class device by GPIO device ID */
+ struct list_head exported_lines;
};
/*
@@ -686,10 +690,10 @@ static void gpiod_attr_init(struct device_attribute *dev_attr, const char *name,
*/
int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
{
+ struct gpiodev_data *gdev_data;
struct gpiod_data *desc_data;
struct gpio_device *gdev;
struct attribute **attrs;
- struct device *dev;
int status;
/* can't export until sysfs is available ... */
@@ -751,25 +755,40 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
desc_data->attr_group.attrs = desc_data->attrs;
desc_data->attr_groups[0] = &desc_data->attr_group;
- dev = device_create_with_groups(&gpio_class, &gdev->dev,
- MKDEV(0, 0), desc_data,
- desc_data->attr_groups,
- "gpio%u", desc_to_gpio(desc));
- if (IS_ERR(dev)) {
- status = PTR_ERR(dev);
+ /*
+ * Note: we need to continue passing desc_data here as there's still
+ * at least one known user of gpiod_export_link() in the tree. This
+ * function still uses class_find_device() internally.
+ */
+ desc_data->dev = device_create_with_groups(&gpio_class, &gdev->dev,
+ MKDEV(0, 0), desc_data,
+ desc_data->attr_groups,
+ "gpio%u",
+ desc_to_gpio(desc));
+ if (IS_ERR(desc_data->dev)) {
+ status = PTR_ERR(desc_data->dev);
goto err_free_data;
}
- desc_data->value_class_node = sysfs_get_dirent(dev->kobj.sd, "value");
+ desc_data->value_class_node = sysfs_get_dirent(desc_data->dev->kobj.sd,
+ "value");
if (!desc_data->value_class_node) {
status = -ENODEV;
goto err_unregister_device;
}
+ gdev_data = gdev_get_data(gdev);
+ if (!gdev_data) {
+ status = -ENODEV;
+ goto err_unregister_device;
+ }
+
+ list_add(&desc_data->list, &gdev_data->exported_lines);
+
return 0;
err_unregister_device:
- device_unregister(dev);
+ device_unregister(desc_data->dev);
err_free_data:
kfree(desc_data);
err_clear_bit:
@@ -828,8 +847,9 @@ EXPORT_SYMBOL_GPL(gpiod_export_link);
*/
void gpiod_unexport(struct gpio_desc *desc)
{
- struct gpiod_data *desc_data;
- struct device *dev;
+ struct gpiod_data *desc_data = NULL;
+ struct gpiodev_data *gdev_data;
+ struct gpio_device *gdev;
if (!desc) {
pr_warn("%s: invalid GPIO\n", __func__);
@@ -840,14 +860,22 @@ void gpiod_unexport(struct gpio_desc *desc)
if (!test_bit(FLAG_EXPORT, &desc->flags))
return;
- dev = class_find_device(&gpio_class, NULL, desc, match_export);
- if (!dev)
+ gdev = gpiod_to_gpio_device(desc);
+ gdev_data = gdev_get_data(gdev);
+ if (!gdev_data)
return;
- desc_data = dev_get_drvdata(dev);
+ list_for_each_entry(desc_data, &gdev_data->exported_lines, list)
+ if (desc == desc_data->desc)
+ break;
+
+ if (!desc_data)
+ return;
+
+ list_del(&desc_data->list);
clear_bit(FLAG_EXPORT, &desc->flags);
sysfs_put(desc_data->value_class_node);
- device_unregister(dev);
+ device_unregister(desc_data->dev);
/*
* Release irq after deregistration to prevent race with
@@ -857,7 +885,6 @@ void gpiod_unexport(struct gpio_desc *desc)
gpio_sysfs_free_irq(desc_data);
}
- put_device(dev);
mutex_destroy(&desc_data->mutex);
kfree(desc_data);
}
@@ -898,6 +925,7 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
return -ENOMEM;
data->gdev = gdev;
+ INIT_LIST_HEAD(&data->exported_lines);
guard(mutex)(&sysfs_lock);
--
2.48.1
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