[PATCH v4 00/10] gpio: sysfs: add a per-chip export/unexport attribute pair

[PATCH v4 00/10] gpio: sysfs: add a per-chip export/unexport attribute pair

[Bartosz Golaszewski]

Following our discussion[1], here's a proposal for extending the sysfs
interface with attributes not referring to GPIO lines by their global
numbers in a backward compatible way.

Long story short: there is now a new class device for each GPIO chip.
It's called chipX where X is the ID of the device as per the driver
model and it lives next to the old gpiochipABC where ABC is the GPIO
base. Each new chip class device has a pair of export/unexport
attributes which work similarly to the global ones under /sys/class/gpio
but take hardware offsets within the chip as input, instead of the
global numbers. Finally, each exported line appears at the same time as
the global /sys/class/gpio/gpioABC as well as per-chip
/sys/class/gpio/chipX/gpioY sysfs group except that the latter only
implements a minimal subset of the functionality of the former, namely:
only the 'direction' and 'value' attributes and it doesn't support event
polling.

The series contains the implementation of a parallel GPIO chip entry not
containing the base GPIO number in the name and the corresponding sysfs
attribute group for each exported line that lives under the new chip
class device as well as a way to allow to compile out the legacy parts
leaving only the new elements of the sysfs ABI.

This series passes the compatibility tests I wrote while working on the
user-space compatibility layer for sysfs[2].

[1] https://lore.kernel.org/all/CAMRc=McUCeZcU6co1aN54rTudo+JfPjjForu4iKQ5npwXk6GXA@mail.gmail.com/
[2] https://github.com/brgl/gpio-sysfs-compat-tests

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
Changes in v4:
- make the chip-local, per-line attribute group only have a minimal subset
  of the functionality of the line class device that exists now: only
  expose the direction and value attributes and disable event polling
  for the latter
- subsequently allow to compile-out the code supporting interrupts and
  `edge` and `active_low` attributes
- only add the line to the list of exported lines at the very end of a
  successful gpiod_export()
- add a TODO task to track the removal of the legacy sysfs bits
- Link to v3: https://lore.kernel.org/r/20250630-gpio-sysfs-chip-export-v3-0-b997be9b7137@linaro.org

Changes in v3:
- wrap a local variable in #ifdef's as it's only used if legacy sysfs
  ABI is enabled (Geert)
- fix an issue with jumping over a variable annotated with __free()
- use gpiod_is_equal() where applicable
- fix a use-after-free issue
- remove trailing commas from NULL array terminators
- improve commit messages
- change patch order for smaller diffstats and better readability
- put struct list_head at the beginning of structures for better
  performance
- reshuffle the contents of struct gpiodev_data: put all legacy fields
  at the end
- don't break lines too eagerly
- Link to v2: https://lore.kernel.org/r/20250623-gpio-sysfs-chip-export-v2-0-d592793f8964@linaro.org

Changes in v2:
- add missing call to sysfs_remove_groups() in gpiod_unexport()
- pick up review tags
- drop patches that were already applied
- add missing documentation for the chip-local line attributes
- correct the statement about chip's label uniqueness in docs
- Link to v1: https://lore.kernel.org/r/20250610-gpio-sysfs-chip-export-v1-0-a8c7aa4478b1@linaro.org

---
Bartosz Golaszewski (10):
      gpio: sysfs: use gpiod_is_equal() to compare GPIO descriptors
      gpio: sysfs: add a parallel class device for each GPIO chip using device IDs
      gpio: sysfs: only get the dirent reference for the value attr once
      gpio: sysfs: pass gpiod_data directly to internal GPIO sysfs functions
      gpio: sysfs: rename the data variable in gpiod_(un)export()
      gpio: sysfs: don't use driver data in sysfs callbacks for line attributes
      gpio: sysfs: don't look up exported lines as class devices
      gpio: sysfs: export the GPIO directory locally in the gpiochip<id> directory
      gpio: sysfs: allow disabling the legacy parts of the GPIO sysfs interface
      gpio: TODO: remove the task for the sysfs rework

 Documentation/ABI/obsolete/sysfs-gpio |  10 +-
 drivers/gpio/Kconfig                  |   8 +
 drivers/gpio/TODO                     |  14 +-
 drivers/gpio/gpiolib-sysfs.c          | 522 +++++++++++++++++++++++++---------
 4 files changed, 412 insertions(+), 142 deletions(-)
---
base-commit: 8d6c58332c7a8ba025fcfa76888b6c37dbce9633
change-id: 20250402-gpio-sysfs-chip-export-84ac424b61c5

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

[PATCH v4 01/10] gpio: sysfs: use gpiod_is_equal() to compare GPIO descriptors

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

We have a dedicated comparator for GPIO descriptors that performs
additional checks and hides the implementation detail of whether the
same GPIO can be associated with two separate struct gpio_desc objects.
Use it in sysfs code

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/gpio/gpiolib-sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index c4c21e25c682b939e4a0517393308343feb6585a..c4e85f2827697d0239ff6296caf49d243cf10fe8 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -657,7 +657,7 @@ static int match_export(struct device *dev, const void *desc)
 {
 	struct gpiod_data *data = dev_get_drvdata(dev);
 
-	return data->desc == desc;
+	return gpiod_is_equal(data->desc, desc);
 }
 
 /**

-- 
2.48.1

[PATCH v4 02/10] gpio: sysfs: add a parallel class device for each GPIO chip using device IDs

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

In order to enable moving away from the global GPIO numberspace-based
exporting of lines over sysfs: add a parallel, per-chip entry under
/sys/class/gpio/ for every registered GPIO chip, denoted by device ID
in the file name and not its base GPIO number.

Compared to the existing chip group: it does not contain the "base"
attribute as the goal of this change is to not refer to GPIOs by their
global number from user-space anymore. It also contains its own,
per-chip export/unexport attribute pair which allow to export lines by
their hardware offset within the chip.

Caveat #1: the new device cannot be a link to (or be linked to by) the
existing "gpiochip<BASE>" entry as we cannot create links in
/sys/class/xyz/.

Caveat #2: the new entry cannot be named "gpiochipX" as it could
conflict with devices whose base is statically defined to a low number.
Let's go with "chipX" instead.

While at it: the chip label is unique so update the untrue statement
when extending the docs.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 Documentation/ABI/obsolete/sysfs-gpio |   7 +-
 drivers/gpio/gpiolib-sysfs.c          | 192 +++++++++++++++++++++++++---------
 2 files changed, 150 insertions(+), 49 deletions(-)

diff --git a/Documentation/ABI/obsolete/sysfs-gpio b/Documentation/ABI/obsolete/sysfs-gpio
index 480316fee6d80fb7a0ed61706559838591ec0932..ff694708a3bef787afa42dedf94faf209c44dbf0 100644
--- a/Documentation/ABI/obsolete/sysfs-gpio
+++ b/Documentation/ABI/obsolete/sysfs-gpio
@@ -25,8 +25,13 @@ Description:
 	    /active_low ... r/w as: 0, 1
 	/gpiochipN ... for each gpiochip; #N is its first GPIO
 	    /base ... (r/o) same as N
-	    /label ... (r/o) descriptive, not necessarily unique
+	    /label ... (r/o) descriptive chip name
 	    /ngpio ... (r/o) number of GPIOs; numbered N to N + (ngpio - 1)
+	/chipX ... for each gpiochip; #X is the gpio device ID
+	    /export ... asks the kernel to export a GPIO at HW offset X to userspace
+	    /unexport ... to return a GPIO at HW offset X to the kernel
+	    /label ... (r/o) descriptive chip name
+	    /ngpio ... (r/o) number of GPIOs exposed by the chip
 
   This ABI is obsoleted by Documentation/ABI/testing/gpio-cdev and will be
   removed after 2020.
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index c4e85f2827697d0239ff6296caf49d243cf10fe8..990db0405cc86c42bad61295dc823f970199534e 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -45,6 +45,7 @@ struct gpiod_data {
 
 struct gpiodev_data {
 	struct gpio_device *gdev;
+	struct device *cdev_id; /* Class device by GPIO device ID */
 	struct device *cdev_base; /* Class device by GPIO base */
 };
 
@@ -399,6 +400,14 @@ static const struct attribute_group *gpio_groups[] = {
  *   /base ... matching gpio_chip.base (N)
  *   /label ... matching gpio_chip.label
  *   /ngpio ... matching gpio_chip.ngpio
+ *
+ * AND
+ *
+ * /sys/class/gpio/chipX/
+ *   /export ... export GPIO at given offset
+ *   /unexport ... unexport GPIO at given offset
+ *   /label ... matching gpio_chip.label
+ *   /ngpio ... matching gpio_chip.ngpio
  */
 
 static ssize_t base_show(struct device *dev, struct device_attribute *attr,
@@ -428,6 +437,111 @@ static ssize_t ngpio_show(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RO(ngpio);
 
+static int export_gpio_desc(struct gpio_desc *desc)
+{
+	int offset, ret;
+
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return -ENODEV;
+
+	offset = gpio_chip_hwgpio(desc);
+	if (!gpiochip_line_is_valid(guard.gc, offset)) {
+		pr_debug_ratelimited("%s: GPIO %d masked\n", __func__,
+				     gpio_chip_hwgpio(desc));
+		return -EINVAL;
+	}
+
+	/*
+	 * No extra locking here; FLAG_SYSFS just signifies that the
+	 * request and export were done by on behalf of userspace, so
+	 * they may be undone on its behalf too.
+	 */
+
+	ret = gpiod_request_user(desc, "sysfs");
+	if (ret)
+		return ret;
+
+	ret = gpiod_set_transitory(desc, false);
+	if (ret) {
+		gpiod_free(desc);
+		return ret;
+	}
+
+	ret = gpiod_export(desc, true);
+	if (ret < 0) {
+		gpiod_free(desc);
+	} else {
+		set_bit(FLAG_SYSFS, &desc->flags);
+		gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_REQUESTED);
+	}
+
+	return ret;
+}
+
+static int unexport_gpio_desc(struct gpio_desc *desc)
+{
+	/*
+	 * No extra locking here; FLAG_SYSFS just signifies that the
+	 * request and export were done by on behalf of userspace, so
+	 * they may be undone on its behalf too.
+	 */
+	if (!test_and_clear_bit(FLAG_SYSFS, &desc->flags))
+		return -EINVAL;
+
+	gpiod_unexport(desc);
+	gpiod_free(desc);
+
+	return 0;
+}
+
+static ssize_t do_chip_export_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, ssize_t size,
+				    int (*handler)(struct gpio_desc *desc))
+{
+	struct gpiodev_data *data = dev_get_drvdata(dev);
+	struct gpio_device *gdev = data->gdev;
+	struct gpio_desc *desc;
+	unsigned int gpio;
+	int ret;
+
+	ret = kstrtouint(buf, 0, &gpio);
+	if (ret)
+		return ret;
+
+	desc = gpio_device_get_desc(gdev, gpio);
+	if (IS_ERR(desc))
+		return PTR_ERR(desc);
+
+	ret = handler(desc);
+	if (ret)
+		return ret;
+
+	return size;
+}
+
+static ssize_t chip_export_store(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buf, size_t size)
+{
+	return do_chip_export_store(dev, attr, buf, size, export_gpio_desc);
+}
+
+static struct device_attribute dev_attr_export = __ATTR(export, 0200, NULL,
+							chip_export_store);
+
+static ssize_t chip_unexport_store(struct device *dev,
+				   struct device_attribute *attr,
+				   const char *buf, size_t size)
+{
+	return do_chip_export_store(dev, attr, buf, size, unexport_gpio_desc);
+}
+
+static struct device_attribute dev_attr_unexport = __ATTR(unexport, 0200,
+							  NULL,
+							  chip_unexport_store);
+
 static struct attribute *gpiochip_attrs[] = {
 	&dev_attr_base.attr,
 	&dev_attr_label.attr,
@@ -436,6 +550,15 @@ static struct attribute *gpiochip_attrs[] = {
 };
 ATTRIBUTE_GROUPS(gpiochip);
 
+static struct attribute *gpiochip_ext_attrs[] = {
+	&dev_attr_label.attr,
+	&dev_attr_ngpio.attr,
+	&dev_attr_export.attr,
+	&dev_attr_unexport.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(gpiochip_ext);
+
 /*
  * /sys/class/gpio/export ... write-only
  *	integer N ... number of GPIO to export (full access)
@@ -447,7 +570,7 @@ static ssize_t export_store(const struct class *class,
 			    const char *buf, size_t len)
 {
 	struct gpio_desc *desc;
-	int status, offset;
+	int status;
 	long gpio;
 
 	status = kstrtol(buf, 0, &gpio);
@@ -461,40 +584,7 @@ static ssize_t export_store(const struct class *class,
 		return -EINVAL;
 	}
 
-	CLASS(gpio_chip_guard, guard)(desc);
-	if (!guard.gc)
-		return -ENODEV;
-
-	offset = gpio_chip_hwgpio(desc);
-	if (!gpiochip_line_is_valid(guard.gc, offset)) {
-		pr_debug_ratelimited("%s: GPIO %ld masked\n", __func__, gpio);
-		return -EINVAL;
-	}
-
-	/* No extra locking here; FLAG_SYSFS just signifies that the
-	 * request and export were done by on behalf of userspace, so
-	 * they may be undone on its behalf too.
-	 */
-
-	status = gpiod_request_user(desc, "sysfs");
-	if (status)
-		goto done;
-
-	status = gpiod_set_transitory(desc, false);
-	if (status) {
-		gpiod_free(desc);
-		goto done;
-	}
-
-	status = gpiod_export(desc, true);
-	if (status < 0) {
-		gpiod_free(desc);
-	} else {
-		set_bit(FLAG_SYSFS, &desc->flags);
-		gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_REQUESTED);
-	}
-
-done:
+	status = export_gpio_desc(desc);
 	if (status)
 		pr_debug("%s: status %d\n", __func__, status);
 	return status ? : len;
@@ -511,7 +601,7 @@ static ssize_t unexport_store(const struct class *class,
 
 	status = kstrtol(buf, 0, &gpio);
 	if (status < 0)
-		goto done;
+		return status;
 
 	desc = gpio_to_desc(gpio);
 	/* reject bogus commands (gpiod_unexport() ignores them) */
@@ -520,18 +610,7 @@ static ssize_t unexport_store(const struct class *class,
 		return -EINVAL;
 	}
 
-	status = -EINVAL;
-
-	/* No extra locking here; FLAG_SYSFS just signifies that the
-	 * request and export were done by on behalf of userspace, so
-	 * they may be undone on its behalf too.
-	 */
-	if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
-		gpiod_unexport(desc);
-		gpiod_free(desc);
-		status = 0;
-	}
-done:
+	status = unexport_gpio_desc(desc);
 	if (status)
 		pr_debug("%s: status %d\n", __func__, status);
 	return status ? : len;
@@ -561,6 +640,11 @@ static int match_gdev(struct device *dev, const void *desc)
 static struct gpiodev_data *
 gdev_get_data(struct gpio_device *gdev) __must_hold(&sysfs_lock)
 {
+	/*
+	 * Find the first device in GPIO class that matches. Whether that's
+	 * the one indexed by GPIO base or device ID doesn't matter, it has
+	 * the same address set as driver data.
+	 */
 	struct device *cdev __free(put_device) = class_find_device(&gpio_class,
 								   NULL, gdev,
 								   match_gdev);
@@ -787,6 +871,17 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
 		return err;
 	}
 
+	data->cdev_id = device_create_with_groups(&gpio_class, parent,
+						  MKDEV(0, 0), data,
+						  gpiochip_ext_groups,
+						  "chip%d", gdev->id);
+	if (IS_ERR(data->cdev_id)) {
+		device_unregister(data->cdev_base);
+		err = PTR_ERR(data->cdev_id);
+		kfree(data);
+		return err;
+	}
+
 	return 0;
 }
 
@@ -802,6 +897,7 @@ void gpiochip_sysfs_unregister(struct gpio_device *gdev)
 			return;
 
 		device_unregister(data->cdev_base);
+		device_unregister(data->cdev_id);
 		kfree(data);
 	}
 

-- 
2.48.1

[PATCH v4 03/10] gpio: sysfs: only get the dirent reference for the value attr once

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

There's no reason to retrieve the reference to the sysfs dirent every
time we request an interrupt, we can as well only do it once when
exporting the GPIO.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/gpio/gpiolib-sysfs.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 990db0405cc86c42bad61295dc823f970199534e..39e9ca31f034e20abd08fb5e9b4eecf24f127d5e 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -177,10 +177,6 @@ static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
 	if (data->irq < 0)
 		return -EIO;
 
-	data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
-	if (!data->value_kn)
-		return -ENODEV;
-
 	irq_flags = IRQF_SHARED;
 	if (flags & GPIO_IRQF_TRIGGER_FALLING) {
 		irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
@@ -203,7 +199,7 @@ static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
 	 */
 	ret = gpiochip_lock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
 	if (ret < 0)
-		goto err_put_kn;
+		goto err_clr_bits;
 
 	ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
 				"gpiolib", data);
@@ -216,10 +212,9 @@ static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
 
 err_unlock:
 	gpiochip_unlock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
-err_put_kn:
+err_clr_bits:
 	clear_bit(FLAG_EDGE_RISING, &desc->flags);
 	clear_bit(FLAG_EDGE_FALLING, &desc->flags);
-	sysfs_put(data->value_kn);
 
 	return ret;
 }
@@ -242,7 +237,6 @@ static void gpio_sysfs_free_irq(struct device *dev)
 	gpiochip_unlock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
 	clear_bit(FLAG_EDGE_RISING, &desc->flags);
 	clear_bit(FLAG_EDGE_FALLING, &desc->flags);
-	sysfs_put(data->value_kn);
 }
 
 static const char *const trigger_names[] = {
@@ -726,8 +720,16 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 		goto err_free_data;
 	}
 
+	data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
+	if (!data->value_kn) {
+		status = -ENODEV;
+		goto err_unregister_device;
+	}
+
 	return 0;
 
+err_unregister_device:
+	device_unregister(dev);
 err_free_data:
 	kfree(data);
 err_clear_bit:
@@ -804,6 +806,7 @@ void gpiod_unexport(struct gpio_desc *desc)
 
 		data = dev_get_drvdata(dev);
 		clear_bit(FLAG_EXPORT, &desc->flags);
+		sysfs_put(data->value_kn);
 		device_unregister(dev);
 
 		/*

-- 
2.48.1

[PATCH v4 04/10] gpio: sysfs: pass gpiod_data directly to internal GPIO sysfs functions

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

We don't use any fields from struct device in gpio_sysfs_request_irq(),
gpio_sysfs_free_irq() and gpio_sysfs_set_active_low(). We only use the
dev argument to get the associated struct gpiod_data pointer with
dev_get_drvdata().

To make the transition to not using dev_get_drvdata() across line
callbacks for sysfs attributes easier, pass gpiod_data directly to
these functions instead of having it wrapped in struct device.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/gpio/gpiolib-sysfs.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 39e9ca31f034e20abd08fb5e9b4eecf24f127d5e..0cfa73e92b47fd089b973e96b5062694b7f8abd3 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -162,9 +162,8 @@ static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
 }
 
 /* Caller holds gpiod-data mutex. */
-static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
+static int gpio_sysfs_request_irq(struct gpiod_data *data, unsigned char flags)
 {
-	struct gpiod_data *data = dev_get_drvdata(dev);
 	struct gpio_desc *desc = data->desc;
 	unsigned long irq_flags;
 	int ret;
@@ -223,9 +222,8 @@ static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
  * Caller holds gpiod-data mutex (unless called after class-device
  * deregistration).
  */
-static void gpio_sysfs_free_irq(struct device *dev)
+static void gpio_sysfs_free_irq(struct gpiod_data *data)
 {
-	struct gpiod_data *data = dev_get_drvdata(dev);
 	struct gpio_desc *desc = data->desc;
 
 	CLASS(gpio_chip_guard, guard)(desc);
@@ -278,12 +276,12 @@ static ssize_t edge_store(struct device *dev, struct device_attribute *attr,
 		return size;
 
 	if (data->irq_flags)
-		gpio_sysfs_free_irq(dev);
+		gpio_sysfs_free_irq(data);
 
 	if (!flags)
 		return size;
 
-	status = gpio_sysfs_request_irq(dev, flags);
+	status = gpio_sysfs_request_irq(data, flags);
 	if (status)
 		return status;
 
@@ -294,9 +292,8 @@ static ssize_t edge_store(struct device *dev, struct device_attribute *attr,
 static DEVICE_ATTR_RW(edge);
 
 /* Caller holds gpiod-data mutex. */
-static int gpio_sysfs_set_active_low(struct device *dev, int value)
+static int gpio_sysfs_set_active_low(struct gpiod_data *data, int value)
 {
-	struct gpiod_data *data = dev_get_drvdata(dev);
 	unsigned int flags = data->irq_flags;
 	struct gpio_desc *desc = data->desc;
 	int status = 0;
@@ -309,8 +306,8 @@ static int gpio_sysfs_set_active_low(struct device *dev, int value)
 	/* reconfigure poll(2) support if enabled on one edge only */
 	if (flags == GPIO_IRQF_TRIGGER_FALLING ||
 	    flags == GPIO_IRQF_TRIGGER_RISING) {
-		gpio_sysfs_free_irq(dev);
-		status = gpio_sysfs_request_irq(dev, flags);
+		gpio_sysfs_free_irq(data);
+		status = gpio_sysfs_request_irq(data, flags);
 	}
 
 	gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_CONFIG);
@@ -345,7 +342,7 @@ static ssize_t active_low_store(struct device *dev,
 
 	guard(mutex)(&data->mutex);
 
-	return gpio_sysfs_set_active_low(dev, value) ?: size;
+	return gpio_sysfs_set_active_low(data, value) ?: size;
 }
 static DEVICE_ATTR_RW(active_low);
 
@@ -814,7 +811,7 @@ void gpiod_unexport(struct gpio_desc *desc)
 		 * edge_store.
 		 */
 		if (data->irq_flags)
-			gpio_sysfs_free_irq(dev);
+			gpio_sysfs_free_irq(data);
 	}
 
 	put_device(dev);

-- 
2.48.1

[PATCH v4 05/10] gpio: sysfs: rename the data variable in gpiod_(un)export()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

In preparation for future commits which will make use of descriptor AND
GPIO-device data in the same functions rename the former from data to
desc_data separately which will make future changes smaller and easier
to read.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/gpio/gpiolib-sysfs.c | 36 ++++++++++++++++++------------------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 0cfa73e92b47fd089b973e96b5062694b7f8abd3..fc9c19fde3f12c16a26aa09dcb6f17960942c4bd 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -663,8 +663,8 @@ gdev_get_data(struct gpio_device *gdev) __must_hold(&sysfs_lock)
  */
 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 {
+	struct gpiod_data *desc_data;
 	struct gpio_device *gdev;
-	struct gpiod_data *data;
 	struct device *dev;
 	int status;
 
@@ -696,29 +696,29 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 		goto err_clear_bit;
 	}
 
-	data = kzalloc(sizeof(*data), GFP_KERNEL);
-	if (!data) {
+	desc_data = kzalloc(sizeof(*desc_data), GFP_KERNEL);
+	if (!desc_data) {
 		status = -ENOMEM;
 		goto err_clear_bit;
 	}
 
-	data->desc = desc;
-	mutex_init(&data->mutex);
+	desc_data->desc = desc;
+	mutex_init(&desc_data->mutex);
 	if (guard.gc->direction_input && guard.gc->direction_output)
-		data->direction_can_change = direction_may_change;
+		desc_data->direction_can_change = direction_may_change;
 	else
-		data->direction_can_change = false;
+		desc_data->direction_can_change = false;
 
 	dev = device_create_with_groups(&gpio_class, &gdev->dev,
-					MKDEV(0, 0), data, gpio_groups,
+					MKDEV(0, 0), desc_data, gpio_groups,
 					"gpio%u", desc_to_gpio(desc));
 	if (IS_ERR(dev)) {
 		status = PTR_ERR(dev);
 		goto err_free_data;
 	}
 
-	data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
-	if (!data->value_kn) {
+	desc_data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
+	if (!desc_data->value_kn) {
 		status = -ENODEV;
 		goto err_unregister_device;
 	}
@@ -728,7 +728,7 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 err_unregister_device:
 	device_unregister(dev);
 err_free_data:
-	kfree(data);
+	kfree(desc_data);
 err_clear_bit:
 	clear_bit(FLAG_EXPORT, &desc->flags);
 	gpiod_dbg(desc, "%s: status %d\n", __func__, status);
@@ -785,7 +785,7 @@ EXPORT_SYMBOL_GPL(gpiod_export_link);
  */
 void gpiod_unexport(struct gpio_desc *desc)
 {
-	struct gpiod_data *data;
+	struct gpiod_data *desc_data;
 	struct device *dev;
 
 	if (!desc) {
@@ -801,22 +801,22 @@ void gpiod_unexport(struct gpio_desc *desc)
 		if (!dev)
 			return;
 
-		data = dev_get_drvdata(dev);
+		desc_data = dev_get_drvdata(dev);
 		clear_bit(FLAG_EXPORT, &desc->flags);
-		sysfs_put(data->value_kn);
+		sysfs_put(desc_data->value_kn);
 		device_unregister(dev);
 
 		/*
 		 * Release irq after deregistration to prevent race with
 		 * edge_store.
 		 */
-		if (data->irq_flags)
-			gpio_sysfs_free_irq(data);
+		if (desc_data->irq_flags)
+			gpio_sysfs_free_irq(desc_data);
 	}
 
 	put_device(dev);
-	mutex_destroy(&data->mutex);
-	kfree(data);
+	mutex_destroy(&desc_data->mutex);
+	kfree(desc_data);
 }
 EXPORT_SYMBOL_GPL(gpiod_unexport);
 

-- 
2.48.1

[PATCH v4 06/10] gpio: sysfs: don't use driver data in sysfs callbacks for line attributes

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Currently each exported GPIO is represented in sysfs as a separate class
device. This allows us to simply use dev_get_drvdata() to retrieve the
pointer passed to device_create_with_groups() from sysfs ops callbacks.

However, we're preparing to add a parallel set of per-line sysfs
attributes that will live inside the associated gpiochip group. They are
not registered as class devices and so have the parent device passed as
argument to their callbacks (the GPIO chip class device).

Put the attribute structs inside the GPIO descriptor data and
dereference the relevant ones using container_of() in the callbacks.
This way, we'll be able to reuse the same code for both the legacy and
new GPIO attributes.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/gpio/gpiolib-sysfs.c | 123 +++++++++++++++++++++++++++++--------------
 1 file changed, 83 insertions(+), 40 deletions(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index fc9c19fde3f12c16a26aa09dcb6f17960942c4bd..e10d720ee0adb3b0f6e91eccbf64c33e5700c616 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -32,6 +32,15 @@ struct kernfs_node;
 #define GPIO_IRQF_TRIGGER_BOTH		(GPIO_IRQF_TRIGGER_FALLING | \
 					 GPIO_IRQF_TRIGGER_RISING)
 
+enum {
+	GPIO_SYSFS_LINE_CLASS_ATTR_DIRECTION = 0,
+	GPIO_SYSFS_LINE_CLASS_ATTR_VALUE,
+	GPIO_SYSFS_LINE_CLASS_ATTR_EDGE,
+	GPIO_SYSFS_LINE_CLASS_ATTR_ACTIVE_LOW,
+	GPIO_SYSFS_LINE_CLASS_ATTR_SENTINEL,
+	GPIO_SYSFS_LINE_CLASS_ATTR_SIZE,
+};
+
 struct gpiod_data {
 	struct gpio_desc *desc;
 
@@ -41,6 +50,15 @@ struct gpiod_data {
 	unsigned char irq_flags;
 
 	bool direction_can_change;
+
+	struct device_attribute dir_attr;
+	struct device_attribute val_attr;
+	struct device_attribute edge_attr;
+	struct device_attribute active_low_attr;
+
+	struct attribute *class_attrs[GPIO_SYSFS_LINE_CLASS_ATTR_SIZE];
+	struct attribute_group class_attr_group;
+	const struct attribute_group *class_attr_groups[2];
 };
 
 struct gpiodev_data {
@@ -79,7 +97,8 @@ static DEFINE_MUTEX(sysfs_lock);
 static ssize_t direction_show(struct device *dev,
 			      struct device_attribute *attr, char *buf)
 {
-	struct gpiod_data *data = dev_get_drvdata(dev);
+	struct gpiod_data *data = container_of(attr, struct gpiod_data,
+					       dir_attr);
 	struct gpio_desc *desc = data->desc;
 	int value;
 
@@ -95,7 +114,8 @@ static ssize_t direction_store(struct device *dev,
 			       struct device_attribute *attr, const char *buf,
 			       size_t size)
 {
-	struct gpiod_data *data = dev_get_drvdata(dev);
+	struct gpiod_data *data = container_of(attr, struct gpiod_data,
+					       dir_attr);
 	struct gpio_desc *desc = data->desc;
 	ssize_t status;
 
@@ -112,12 +132,12 @@ static ssize_t direction_store(struct device *dev,
 
 	return status ? : size;
 }
-static DEVICE_ATTR_RW(direction);
 
 static ssize_t value_show(struct device *dev, struct device_attribute *attr,
 			  char *buf)
 {
-	struct gpiod_data *data = dev_get_drvdata(dev);
+	struct gpiod_data *data = container_of(attr, struct gpiod_data,
+					       val_attr);
 	struct gpio_desc *desc = data->desc;
 	ssize_t status;
 
@@ -133,7 +153,8 @@ static ssize_t value_show(struct device *dev, struct device_attribute *attr,
 static ssize_t value_store(struct device *dev, struct device_attribute *attr,
 			   const char *buf, size_t size)
 {
-	struct gpiod_data *data = dev_get_drvdata(dev);
+	struct gpiod_data *data = container_of(attr, struct gpiod_data,
+					       val_attr);
 	struct gpio_desc *desc = data->desc;
 	ssize_t status;
 	long value;
@@ -150,7 +171,6 @@ static ssize_t value_store(struct device *dev, struct device_attribute *attr,
 
 	return size;
 }
-static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
 
 static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
 {
@@ -247,7 +267,8 @@ static const char *const trigger_names[] = {
 static ssize_t edge_show(struct device *dev, struct device_attribute *attr,
 			 char *buf)
 {
-	struct gpiod_data *data = dev_get_drvdata(dev);
+	struct gpiod_data *data = container_of(attr, struct gpiod_data,
+					       edge_attr);
 	int flags;
 
 	scoped_guard(mutex, &data->mutex)
@@ -262,7 +283,8 @@ static ssize_t edge_show(struct device *dev, struct device_attribute *attr,
 static ssize_t edge_store(struct device *dev, struct device_attribute *attr,
 			  const char *buf, size_t size)
 {
-	struct gpiod_data *data = dev_get_drvdata(dev);
+	struct gpiod_data *data = container_of(attr, struct gpiod_data,
+					       edge_attr);
 	ssize_t status = size;
 	int flags;
 
@@ -289,7 +311,6 @@ static ssize_t edge_store(struct device *dev, struct device_attribute *attr,
 
 	return size;
 }
-static DEVICE_ATTR_RW(edge);
 
 /* Caller holds gpiod-data mutex. */
 static int gpio_sysfs_set_active_low(struct gpiod_data *data, int value)
@@ -318,7 +339,8 @@ static int gpio_sysfs_set_active_low(struct gpiod_data *data, int value)
 static ssize_t active_low_show(struct device *dev,
 			       struct device_attribute *attr, char *buf)
 {
-	struct gpiod_data *data = dev_get_drvdata(dev);
+	struct gpiod_data *data = container_of(attr, struct gpiod_data,
+					       active_low_attr);
 	struct gpio_desc *desc = data->desc;
 	int value;
 
@@ -332,7 +354,8 @@ static ssize_t active_low_store(struct device *dev,
 				struct device_attribute *attr,
 				const char *buf, size_t size)
 {
-	struct gpiod_data *data = dev_get_drvdata(dev);
+	struct gpiod_data *data = container_of(attr, struct gpiod_data,
+					       active_low_attr);
 	ssize_t status;
 	long value;
 
@@ -344,48 +367,34 @@ static ssize_t active_low_store(struct device *dev,
 
 	return gpio_sysfs_set_active_low(data, value) ?: size;
 }
-static DEVICE_ATTR_RW(active_low);
 
 static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
 			       int n)
 {
-	struct device *dev = kobj_to_dev(kobj);
-	struct gpiod_data *data = dev_get_drvdata(dev);
-	struct gpio_desc *desc = data->desc;
+	struct device_attribute *dev_attr = container_of(attr,
+						struct device_attribute, attr);
 	umode_t mode = attr->mode;
-	bool show_direction = data->direction_can_change;
+	struct gpiod_data *data;
 
-	if (attr == &dev_attr_direction.attr) {
-		if (!show_direction)
+	if (strcmp(attr->name, "direction") == 0) {
+		data = container_of(dev_attr, struct gpiod_data, dir_attr);
+
+		if (!data->direction_can_change)
 			mode = 0;
-	} else if (attr == &dev_attr_edge.attr) {
-		if (gpiod_to_irq(desc) < 0)
+	} else if (strcmp(attr->name, "edge") == 0) {
+		data = container_of(dev_attr, struct gpiod_data, edge_attr);
+
+		if (gpiod_to_irq(data->desc) < 0)
 			mode = 0;
-		if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
+
+		if (!data->direction_can_change &&
+		    test_bit(FLAG_IS_OUT, &data->desc->flags))
 			mode = 0;
 	}
 
 	return mode;
 }
 
-static struct attribute *gpio_attrs[] = {
-	&dev_attr_direction.attr,
-	&dev_attr_edge.attr,
-	&dev_attr_value.attr,
-	&dev_attr_active_low.attr,
-	NULL,
-};
-
-static const struct attribute_group gpio_group = {
-	.attrs = gpio_attrs,
-	.is_visible = gpio_is_visible,
-};
-
-static const struct attribute_group *gpio_groups[] = {
-	&gpio_group,
-	NULL
-};
-
 /*
  * /sys/class/gpio/gpiochipN/
  *   /base ... matching gpio_chip.base (N)
@@ -645,6 +654,21 @@ gdev_get_data(struct gpio_device *gdev) __must_hold(&sysfs_lock)
 	return dev_get_drvdata(cdev);
 };
 
+static void gpiod_attr_init(struct device_attribute *dev_attr, const char *name,
+			    ssize_t (*show)(struct device *dev,
+					    struct device_attribute *attr,
+					    char *buf),
+			    ssize_t (*store)(struct device *dev,
+					     struct device_attribute *attr,
+					     const char *buf, size_t count))
+{
+	sysfs_attr_init(&dev_attr->attr);
+	dev_attr->attr.name = name;
+	dev_attr->attr.mode = 0644;
+	dev_attr->show = show;
+	dev_attr->store = store;
+}
+
 /**
  * gpiod_export - export a GPIO through sysfs
  * @desc: GPIO to make available, already requested
@@ -665,6 +689,7 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 {
 	struct gpiod_data *desc_data;
 	struct gpio_device *gdev;
+	struct attribute **attrs;
 	struct device *dev;
 	int status;
 
@@ -709,8 +734,26 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 	else
 		desc_data->direction_can_change = false;
 
+	gpiod_attr_init(&desc_data->dir_attr, "direction",
+			direction_show, direction_store);
+	gpiod_attr_init(&desc_data->val_attr, "value", value_show, value_store);
+	gpiod_attr_init(&desc_data->edge_attr, "edge", edge_show, edge_store);
+	gpiod_attr_init(&desc_data->active_low_attr, "active_low",
+			active_low_show, active_low_store);
+
+	attrs = desc_data->class_attrs;
+	desc_data->class_attr_group.is_visible = gpio_is_visible;
+	attrs[GPIO_SYSFS_LINE_CLASS_ATTR_DIRECTION] = &desc_data->dir_attr.attr;
+	attrs[GPIO_SYSFS_LINE_CLASS_ATTR_VALUE] = &desc_data->val_attr.attr;
+	attrs[GPIO_SYSFS_LINE_CLASS_ATTR_EDGE] = &desc_data->edge_attr.attr;
+	attrs[GPIO_SYSFS_LINE_CLASS_ATTR_ACTIVE_LOW] = &desc_data->active_low_attr.attr;
+
+	desc_data->class_attr_group.attrs = desc_data->class_attrs;
+	desc_data->class_attr_groups[0] = &desc_data->class_attr_group;
+
 	dev = device_create_with_groups(&gpio_class, &gdev->dev,
-					MKDEV(0, 0), desc_data, gpio_groups,
+					MKDEV(0, 0), desc_data,
+					desc_data->class_attr_groups,
 					"gpio%u", desc_to_gpio(desc));
 	if (IS_ERR(dev)) {
 		status = PTR_ERR(dev);

-- 
2.48.1

[PATCH v4 07/10] gpio: sysfs: don't look up exported lines as class devices

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.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.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.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 e10d720ee0adb3b0f6e91eccbf64c33e5700c616..ccc293a4cc5d51294703959317061af55fb0dab0 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -42,7 +42,10 @@ enum {
 };
 
 struct gpiod_data {
+	struct list_head list;
+
 	struct gpio_desc *desc;
+	struct device *dev;
 
 	struct mutex mutex;
 	struct kernfs_node *value_kn;
@@ -62,6 +65,7 @@ struct gpiod_data {
 };
 
 struct gpiodev_data {
+	struct list_head exported_lines;
 	struct gpio_device *gdev;
 	struct device *cdev_id; /* Class device by GPIO device ID */
 	struct device *cdev_base; /* Class device by GPIO base */
@@ -687,10 +691,10 @@ 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->class_attr_group.attrs = desc_data->class_attrs;
 	desc_data->class_attr_groups[0] = &desc_data->class_attr_group;
 
-	dev = device_create_with_groups(&gpio_class, &gdev->dev,
-					MKDEV(0, 0), desc_data,
-					desc_data->class_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->class_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_kn = sysfs_get_dirent(dev->kobj.sd, "value");
+	desc_data->value_kn = sysfs_get_dirent(desc_data->dev->kobj.sd,
+						       "value");
 	if (!desc_data->value_kn) {
 		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 (gpiod_is_equal(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_kn);
-		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);
 }
@@ -899,6 +926,7 @@ 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

[PATCH v4 08/10] gpio: sysfs: export the GPIO directory locally in the gpiochip<id> directory

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

As a way to allow the user-space to stop referring to GPIOs by their
global numbers, introduce a parallel group of line attributes for
exported GPIO that live inside the GPIO chip class device and are
referred to by their HW offset within their parent chip.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 Documentation/ABI/obsolete/sysfs-gpio |  3 +++
 drivers/gpio/gpiolib-sysfs.c          | 51 ++++++++++++++++++++++++++++++++++-
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/obsolete/sysfs-gpio b/Documentation/ABI/obsolete/sysfs-gpio
index ff694708a3bef787afa42dedf94faf209c44dbf0..0d3f12c4dcbde4f93da33707cd36e9acc0ee2fbf 100644
--- a/Documentation/ABI/obsolete/sysfs-gpio
+++ b/Documentation/ABI/obsolete/sysfs-gpio
@@ -27,6 +27,9 @@ Description:
 	    /base ... (r/o) same as N
 	    /label ... (r/o) descriptive chip name
 	    /ngpio ... (r/o) number of GPIOs; numbered N to N + (ngpio - 1)
+	    /gpio<OFFSET>
+	        /value ... always readable, writes fail for input GPIOs
+	        /direction ... r/w as: in, out (default low); write: high, low
 	/chipX ... for each gpiochip; #X is the gpio device ID
 	    /export ... asks the kernel to export a GPIO at HW offset X to userspace
 	    /unexport ... to return a GPIO at HW offset X to the kernel
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index ccc293a4cc5d51294703959317061af55fb0dab0..563e38456c33cd3a6e8674485105ef45ce8f5095 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -41,6 +41,13 @@ enum {
 	GPIO_SYSFS_LINE_CLASS_ATTR_SIZE,
 };
 
+enum {
+	GPIO_SYSFS_LINE_CHIP_ATTR_DIRECTION = 0,
+	GPIO_SYSFS_LINE_CHIP_ATTR_VALUE,
+	GPIO_SYSFS_LINE_CHIP_ATTR_SENTINEL,
+	GPIO_SYSFS_LINE_CHIP_ATTR_SIZE,
+};
+
 struct gpiod_data {
 	struct list_head list;
 
@@ -54,6 +61,7 @@ struct gpiod_data {
 
 	bool direction_can_change;
 
+	struct kobject *parent;
 	struct device_attribute dir_attr;
 	struct device_attribute val_attr;
 	struct device_attribute edge_attr;
@@ -62,6 +70,10 @@ struct gpiod_data {
 	struct attribute *class_attrs[GPIO_SYSFS_LINE_CLASS_ATTR_SIZE];
 	struct attribute_group class_attr_group;
 	const struct attribute_group *class_attr_groups[2];
+
+	struct attribute *chip_attrs[GPIO_SYSFS_LINE_CHIP_ATTR_SIZE];
+	struct attribute_group chip_attr_group;
+	const struct attribute_group *chip_attr_groups[2];
 };
 
 struct gpiodev_data {
@@ -691,6 +703,7 @@ static void gpiod_attr_init(struct device_attribute *dev_attr, const char *name,
  */
 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 {
+	char *path __free(kfree) = NULL;
 	struct gpiodev_data *gdev_data;
 	struct gpiod_data *desc_data;
 	struct gpio_device *gdev;
@@ -780,13 +793,46 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 	gdev_data = gdev_get_data(gdev);
 	if (!gdev_data) {
 		status = -ENODEV;
-		goto err_unregister_device;
+		goto err_put_dirent;
+	}
+
+	desc_data->chip_attr_group.name = kasprintf(GFP_KERNEL, "gpio%u",
+						    gpio_chip_hwgpio(desc));
+	if (!desc_data->chip_attr_group.name) {
+		status = -ENOMEM;
+		goto err_put_dirent;
+	}
+
+	attrs = desc_data->chip_attrs;
+	desc_data->chip_attr_group.is_visible = gpio_is_visible;
+	attrs[GPIO_SYSFS_LINE_CHIP_ATTR_DIRECTION] = &desc_data->dir_attr.attr;
+	attrs[GPIO_SYSFS_LINE_CHIP_ATTR_VALUE] = &desc_data->val_attr.attr;
+
+	desc_data->chip_attr_group.attrs = attrs;
+	desc_data->chip_attr_groups[0] = &desc_data->chip_attr_group;
+
+	desc_data->parent = &gdev_data->cdev_id->kobj;
+	status = sysfs_create_groups(desc_data->parent,
+				     desc_data->chip_attr_groups);
+	if (status)
+		goto err_free_name;
+
+	path = kasprintf(GFP_KERNEL, "gpio%u/value", gpio_chip_hwgpio(desc));
+	if (!path) {
+		status = -ENOMEM;
+		goto err_remove_groups;
 	}
 
 	list_add(&desc_data->list, &gdev_data->exported_lines);
 
 	return 0;
 
+err_remove_groups:
+	sysfs_remove_groups(desc_data->parent, desc_data->chip_attr_groups);
+err_free_name:
+	kfree(desc_data->chip_attr_group.name);
+err_put_dirent:
+	sysfs_put(desc_data->value_kn);
 err_unregister_device:
 	device_unregister(desc_data->dev);
 err_free_data:
@@ -883,6 +929,9 @@ void gpiod_unexport(struct gpio_desc *desc)
 		 */
 		if (desc_data->irq_flags)
 			gpio_sysfs_free_irq(desc_data);
+
+		sysfs_remove_groups(desc_data->parent,
+				    desc_data->chip_attr_groups);
 	}
 
 	mutex_destroy(&desc_data->mutex);

-- 
2.48.1

[PATCH v4 09/10] gpio: sysfs: allow disabling the legacy parts of the GPIO sysfs interface

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Add a Kconfig switch allowing to disable the legacy parts of the GPIO
sysfs interface. This means that even though we keep the
/sys/class/gpio/ directory, it no longer contains the global
export/unexport attribute pair (instead, the user should use the
per-chip export/unpexport) nor the gpiochip$BASE entries. This option
default to y if GPIO sysfs is enabled but we'll default it to n at some
point in the future.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/gpio/Kconfig         |  8 ++++++++
 drivers/gpio/gpiolib-sysfs.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 44f922e10db2f8dcbdacf79ccd27b0fd9cd93564..d040fdd95ee4b19851057fbedbb023f277149c9c 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -69,6 +69,14 @@ config GPIO_SYSFS
 	  use the character device /dev/gpiochipN with the appropriate
 	  ioctl() operations instead.
 
+config GPIO_SYSFS_LEGACY
+	bool "Enable legacy functionalities of the sysfs interface"
+	depends on GPIO_SYSFS
+	default y if GPIO_SYSFS
+	help
+	  Say Y here if you want to enable the legacy, global GPIO
+	  numberspace-based functionalities of the sysfs interface.
+
 config GPIO_CDEV
 	bool "Character device (/dev/gpiochipN) support" if EXPERT
 	default y
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 563e38456c33cd3a6e8674485105ef45ce8f5095..f31adc56bef1e215a257eab37ca3319c55ef36a6 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -24,6 +24,8 @@
 #include "gpiolib.h"
 #include "gpiolib-sysfs.h"
 
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
+
 struct kernfs_node;
 
 #define GPIO_IRQF_TRIGGER_NONE		0
@@ -41,6 +43,8 @@ enum {
 	GPIO_SYSFS_LINE_CLASS_ATTR_SIZE,
 };
 
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
+
 enum {
 	GPIO_SYSFS_LINE_CHIP_ATTR_DIRECTION = 0,
 	GPIO_SYSFS_LINE_CHIP_ATTR_VALUE,
@@ -55,21 +59,26 @@ struct gpiod_data {
 	struct device *dev;
 
 	struct mutex mutex;
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 	struct kernfs_node *value_kn;
 	int irq;
 	unsigned char irq_flags;
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 
 	bool direction_can_change;
 
 	struct kobject *parent;
 	struct device_attribute dir_attr;
 	struct device_attribute val_attr;
+
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 	struct device_attribute edge_attr;
 	struct device_attribute active_low_attr;
 
 	struct attribute *class_attrs[GPIO_SYSFS_LINE_CLASS_ATTR_SIZE];
 	struct attribute_group class_attr_group;
 	const struct attribute_group *class_attr_groups[2];
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 
 	struct attribute *chip_attrs[GPIO_SYSFS_LINE_CHIP_ATTR_SIZE];
 	struct attribute_group chip_attr_group;
@@ -80,7 +89,9 @@ struct gpiodev_data {
 	struct list_head exported_lines;
 	struct gpio_device *gdev;
 	struct device *cdev_id; /* Class device by GPIO device ID */
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 	struct device *cdev_base; /* Class device by GPIO base */
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 };
 
 /*
@@ -188,6 +199,7 @@ static ssize_t value_store(struct device *dev, struct device_attribute *attr,
 	return size;
 }
 
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
 {
 	struct gpiod_data *data = priv;
@@ -383,6 +395,7 @@ static ssize_t active_low_store(struct device *dev,
 
 	return gpio_sysfs_set_active_low(data, value) ?: size;
 }
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 
 static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
 			       int n)
@@ -397,6 +410,7 @@ static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
 
 		if (!data->direction_can_change)
 			mode = 0;
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 	} else if (strcmp(attr->name, "edge") == 0) {
 		data = container_of(dev_attr, struct gpiod_data, edge_attr);
 
@@ -406,6 +420,7 @@ static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
 		if (!data->direction_can_change &&
 		    test_bit(FLAG_IS_OUT, &data->desc->flags))
 			mode = 0;
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 	}
 
 	return mode;
@@ -426,6 +441,7 @@ static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
  *   /ngpio ... matching gpio_chip.ngpio
  */
 
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 static ssize_t base_show(struct device *dev, struct device_attribute *attr,
 			 char *buf)
 {
@@ -434,6 +450,7 @@ static ssize_t base_show(struct device *dev, struct device_attribute *attr,
 	return sysfs_emit(buf, "%u\n", data->gdev->base);
 }
 static DEVICE_ATTR_RO(base);
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 
 static ssize_t label_show(struct device *dev, struct device_attribute *attr,
 			  char *buf)
@@ -558,6 +575,7 @@ static struct device_attribute dev_attr_unexport = __ATTR(unexport, 0200,
 							  NULL,
 							  chip_unexport_store);
 
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 static struct attribute *gpiochip_attrs[] = {
 	&dev_attr_base.attr,
 	&dev_attr_label.attr,
@@ -565,6 +583,7 @@ static struct attribute *gpiochip_attrs[] = {
 	NULL,
 };
 ATTRIBUTE_GROUPS(gpiochip);
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 
 static struct attribute *gpiochip_ext_attrs[] = {
 	&dev_attr_label.attr,
@@ -575,6 +594,7 @@ static struct attribute *gpiochip_ext_attrs[] = {
 };
 ATTRIBUTE_GROUPS(gpiochip_ext);
 
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 /*
  * /sys/class/gpio/export ... write-only
  *	integer N ... number of GPIO to export (full access)
@@ -639,10 +659,13 @@ static struct attribute *gpio_class_attrs[] = {
 	NULL,
 };
 ATTRIBUTE_GROUPS(gpio_class);
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 
 static const struct class gpio_class = {
 	.name =		"gpio",
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 	.class_groups =	gpio_class_groups,
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 };
 
 static int match_gdev(struct device *dev, const void *desc)
@@ -754,6 +777,8 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 	gpiod_attr_init(&desc_data->dir_attr, "direction",
 			direction_show, direction_store);
 	gpiod_attr_init(&desc_data->val_attr, "value", value_show, value_store);
+
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 	gpiod_attr_init(&desc_data->edge_attr, "edge", edge_show, edge_store);
 	gpiod_attr_init(&desc_data->active_low_attr, "active_low",
 			active_low_show, active_low_store);
@@ -789,6 +814,7 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 		status = -ENODEV;
 		goto err_unregister_device;
 	}
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 
 	gdev_data = gdev_get_data(gdev);
 	if (!gdev_data) {
@@ -832,10 +858,12 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 err_free_name:
 	kfree(desc_data->chip_attr_group.name);
 err_put_dirent:
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 	sysfs_put(desc_data->value_kn);
 err_unregister_device:
 	device_unregister(desc_data->dev);
 err_free_data:
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 	kfree(desc_data);
 err_clear_bit:
 	clear_bit(FLAG_EXPORT, &desc->flags);
@@ -844,12 +872,14 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 }
 EXPORT_SYMBOL_GPL(gpiod_export);
 
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 static int match_export(struct device *dev, const void *desc)
 {
 	struct gpiod_data *data = dev_get_drvdata(dev);
 
 	return gpiod_is_equal(data->desc, desc);
 }
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 
 /**
  * gpiod_export_link - create a sysfs link to an exported GPIO node
@@ -866,6 +896,7 @@ static int match_export(struct device *dev, const void *desc)
 int gpiod_export_link(struct device *dev, const char *name,
 		      struct gpio_desc *desc)
 {
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 	struct device *cdev;
 	int ret;
 
@@ -882,6 +913,9 @@ int gpiod_export_link(struct device *dev, const char *name,
 	put_device(cdev);
 
 	return ret;
+#else
+	return -EOPNOTSUPP;
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 }
 EXPORT_SYMBOL_GPL(gpiod_export_link);
 
@@ -920,6 +954,7 @@ void gpiod_unexport(struct gpio_desc *desc)
 
 		list_del(&desc_data->list);
 		clear_bit(FLAG_EXPORT, &desc->flags);
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 		sysfs_put(desc_data->value_kn);
 		device_unregister(desc_data->dev);
 
@@ -929,6 +964,7 @@ void gpiod_unexport(struct gpio_desc *desc)
 		 */
 		if (desc_data->irq_flags)
 			gpio_sysfs_free_irq(desc_data);
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 
 		sysfs_remove_groups(desc_data->parent,
 				    desc_data->chip_attr_groups);
@@ -979,6 +1015,7 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
 
 	guard(mutex)(&sysfs_lock);
 
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 	/* 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,
@@ -990,13 +1027,16 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
 		kfree(data);
 		return err;
 	}
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 
 	data->cdev_id = device_create_with_groups(&gpio_class, parent,
 						  MKDEV(0, 0), data,
 						  gpiochip_ext_groups,
 						  "chip%d", gdev->id);
 	if (IS_ERR(data->cdev_id)) {
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 		device_unregister(data->cdev_base);
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 		err = PTR_ERR(data->cdev_id);
 		kfree(data);
 		return err;
@@ -1016,7 +1056,9 @@ void gpiochip_sysfs_unregister(struct gpio_device *gdev)
 		if (!data)
 			return;
 
+#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
 		device_unregister(data->cdev_base);
+#endif /* CONFIG_GPIO_SYSFS_LEGACY */
 		device_unregister(data->cdev_id);
 		kfree(data);
 	}

-- 
2.48.1

[PATCH v4 10/10] gpio: TODO: remove the task for the sysfs rework

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Remove the completed task tracking the rework of the sysfs interface and
add a new task to track the removal of the legacy bits and pieces.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/gpio/TODO | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/gpio/TODO b/drivers/gpio/TODO
index ef53892cb44d7c01d100f10f1b805c0aca561b46..7a09a4f58551b51c55938c278a47a04e86ef4106 100644
--- a/drivers/gpio/TODO
+++ b/drivers/gpio/TODO
@@ -188,16 +188,12 @@ remove the old ones and finally rename the new ones back to the old names.
 
 -------------------------------------------------------------------------------
 
-Extend the sysfs ABI to allow exporting lines by their HW offsets
+Remove legacy sysfs features
 
-The need to support the sysfs GPIO class is one of the main obstacles to
-removing the global GPIO numberspace from the kernel. In order to wean users
-off using global numbers from user-space, extend the existing interface with
-new per-gpiochip export/unexport attributes that allow to refer to GPIOs using
-their hardware offsets within the chip.
-
-Encourage users to switch to using them and eventually remove the existing
-global export/unexport attribues.
+We have two parallel per-chip class devices and per-exported-line attribute
+groups in sysfs. One is using the obsolete global GPIO numberspace and the
+second relies on hardware offsets of pins within the chip. Remove the former
+once user-space has switched to using the latter.
 
 -------------------------------------------------------------------------------
 

-- 
2.48.1

Re: [PATCH v4 00/10] gpio: sysfs: add a per-chip export/unexport attribute pair

[Bartosz Golaszewski]

On Fri, Jul 4, 2025 at 2:58 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
> Following our discussion[1], here's a proposal for extending the sysfs
> interface with attributes not referring to GPIO lines by their global
> numbers in a backward compatible way.
>
> Long story short: there is now a new class device for each GPIO chip.
> It's called chipX where X is the ID of the device as per the driver
> model and it lives next to the old gpiochipABC where ABC is the GPIO
> base. Each new chip class device has a pair of export/unexport
> attributes which work similarly to the global ones under /sys/class/gpio
> but take hardware offsets within the chip as input, instead of the
> global numbers. Finally, each exported line appears at the same time as
> the global /sys/class/gpio/gpioABC as well as per-chip
> /sys/class/gpio/chipX/gpioY sysfs group except that the latter only
> implements a minimal subset of the functionality of the former, namely:
> only the 'direction' and 'value' attributes and it doesn't support event
> polling.
>
> The series contains the implementation of a parallel GPIO chip entry not
> containing the base GPIO number in the name and the corresponding sysfs
> attribute group for each exported line that lives under the new chip
> class device as well as a way to allow to compile out the legacy parts
> leaving only the new elements of the sysfs ABI.
>
> This series passes the compatibility tests I wrote while working on the
> user-space compatibility layer for sysfs[2].
>
> [1] https://lore.kernel.org/all/CAMRc=McUCeZcU6co1aN54rTudo+JfPjjForu4iKQ5npwXk6GXA@mail.gmail.com/
> [2] https://github.com/brgl/gpio-sysfs-compat-tests
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> ---

Alright, so what are we doing about this? Should I queue these patches
for v6.17? Kent, any additional comments? Geert, Jan: did you have the
chance to test it?

Bart

Re: [PATCH v4 00/10] gpio: sysfs: add a per-chip export/unexport attribute pair

[Kent Gibson]

On Sun, Jul 13, 2025 at 10:48:03AM +0200, Bartosz Golaszewski wrote:
> On Fri, Jul 4, 2025 at 2:58 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> >
> > Following our discussion[1], here's a proposal for extending the sysfs
> > interface with attributes not referring to GPIO lines by their global
> > numbers in a backward compatible way.
> >
> > Long story short: there is now a new class device for each GPIO chip.
> > It's called chipX where X is the ID of the device as per the driver
> > model and it lives next to the old gpiochipABC where ABC is the GPIO
> > base. Each new chip class device has a pair of export/unexport
> > attributes which work similarly to the global ones under /sys/class/gpio
> > but take hardware offsets within the chip as input, instead of the
> > global numbers. Finally, each exported line appears at the same time as
> > the global /sys/class/gpio/gpioABC as well as per-chip
> > /sys/class/gpio/chipX/gpioY sysfs group except that the latter only
> > implements a minimal subset of the functionality of the former, namely:
> > only the 'direction' and 'value' attributes and it doesn't support event
> > polling.
> >
> > The series contains the implementation of a parallel GPIO chip entry not
> > containing the base GPIO number in the name and the corresponding sysfs
> > attribute group for each exported line that lives under the new chip
> > class device as well as a way to allow to compile out the legacy parts
> > leaving only the new elements of the sysfs ABI.
> >
> > This series passes the compatibility tests I wrote while working on the
> > user-space compatibility layer for sysfs[2].
> >
> > [1] https://lore.kernel.org/all/CAMRc=McUCeZcU6co1aN54rTudo+JfPjjForu4iKQ5npwXk6GXA@mail.gmail.com/
> > [2] https://github.com/brgl/gpio-sysfs-compat-tests
> >
> > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> > ---
> 
> Alright, so what are we doing about this? Should I queue these patches
> for v6.17? Kent, any additional comments?

Nothing beyond what I've already said.

Cheers,
Kent.

Re: [PATCH v4 00/10] gpio: sysfs: add a per-chip export/unexport attribute pair

[Bartosz Golaszewski]

On Mon, Jul 14, 2025 at 3:38 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> On Sun, Jul 13, 2025 at 10:48:03AM +0200, Bartosz Golaszewski wrote:
> > On Fri, Jul 4, 2025 at 2:58 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> > >
> > > Following our discussion[1], here's a proposal for extending the sysfs
> > > interface with attributes not referring to GPIO lines by their global
> > > numbers in a backward compatible way.
> > >
> > > Long story short: there is now a new class device for each GPIO chip.
> > > It's called chipX where X is the ID of the device as per the driver
> > > model and it lives next to the old gpiochipABC where ABC is the GPIO
> > > base. Each new chip class device has a pair of export/unexport
> > > attributes which work similarly to the global ones under /sys/class/gpio
> > > but take hardware offsets within the chip as input, instead of the
> > > global numbers. Finally, each exported line appears at the same time as
> > > the global /sys/class/gpio/gpioABC as well as per-chip
> > > /sys/class/gpio/chipX/gpioY sysfs group except that the latter only
> > > implements a minimal subset of the functionality of the former, namely:
> > > only the 'direction' and 'value' attributes and it doesn't support event
> > > polling.
> > >
> > > The series contains the implementation of a parallel GPIO chip entry not
> > > containing the base GPIO number in the name and the corresponding sysfs
> > > attribute group for each exported line that lives under the new chip
> > > class device as well as a way to allow to compile out the legacy parts
> > > leaving only the new elements of the sysfs ABI.
> > >
> > > This series passes the compatibility tests I wrote while working on the
> > > user-space compatibility layer for sysfs[2].
> > >
> > > [1] https://lore.kernel.org/all/CAMRc=McUCeZcU6co1aN54rTudo+JfPjjForu4iKQ5npwXk6GXA@mail.gmail.com/
> > > [2] https://github.com/brgl/gpio-sysfs-compat-tests
> > >
> > > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> > > ---
> >
> > Alright, so what are we doing about this? Should I queue these patches
> > for v6.17? Kent, any additional comments?
>
> Nothing beyond what I've already said.
>
> Cheers,
> Kent.

Ok, let's queue them up for v6.17 then.

Bart

Re: [PATCH v4 00/10] gpio: sysfs: add a per-chip export/unexport attribute pair

[Jan Lübbe]

On Sun, 2025-07-13 at 10:48 +0200, Bartosz Golaszewski wrote:
> Alright, so what are we doing about this? Should I queue these patches
> for v6.17? Kent, any additional comments? Geert, Jan: did you have the
> chance to test it?

I've tried it out and didn't find any issues.

Thanks a lot for implementing this!

Regards,
Jan

Re: [PATCH v4 00/10] gpio: sysfs: add a per-chip export/unexport attribute pair

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>


On Fri, 04 Jul 2025 14:58:47 +0200, Bartosz Golaszewski wrote:
> Following our discussion[1], here's a proposal for extending the sysfs
> interface with attributes not referring to GPIO lines by their global
> numbers in a backward compatible way.
> 
> Long story short: there is now a new class device for each GPIO chip.
> It's called chipX where X is the ID of the device as per the driver
> model and it lives next to the old gpiochipABC where ABC is the GPIO
> base. Each new chip class device has a pair of export/unexport
> attributes which work similarly to the global ones under /sys/class/gpio
> but take hardware offsets within the chip as input, instead of the
> global numbers. Finally, each exported line appears at the same time as
> the global /sys/class/gpio/gpioABC as well as per-chip
> /sys/class/gpio/chipX/gpioY sysfs group except that the latter only
> implements a minimal subset of the functionality of the former, namely:
> only the 'direction' and 'value' attributes and it doesn't support event
> polling.
> 
> [...]

Applied, thanks!

[01/10] gpio: sysfs: use gpiod_is_equal() to compare GPIO descriptors
        https://git.kernel.org/brgl/linux/c/32ad0b9a17f9aa8dd9308feda671bda98b274d24
[02/10] gpio: sysfs: add a parallel class device for each GPIO chip using device IDs
        https://git.kernel.org/brgl/linux/c/2028f854b3f5b3816cd5d5dd83057a873eddc4d6
[03/10] gpio: sysfs: only get the dirent reference for the value attr once
        https://git.kernel.org/brgl/linux/c/c38c3a349b7bb994252e93c7c122fa0b50ddf12b
[04/10] gpio: sysfs: pass gpiod_data directly to internal GPIO sysfs functions
        https://git.kernel.org/brgl/linux/c/7c49c1298f3ab3331008e85ac22b2d32b4bb450f
[05/10] gpio: sysfs: rename the data variable in gpiod_(un)export()
        https://git.kernel.org/brgl/linux/c/12faec7ed1793221c1dc9f69575a814528d74691
[06/10] gpio: sysfs: don't use driver data in sysfs callbacks for line attributes
        https://git.kernel.org/brgl/linux/c/f7d4fb62d04542646a48de08b10354692f3b98ce
[07/10] gpio: sysfs: don't look up exported lines as class devices
        https://git.kernel.org/brgl/linux/c/1cd53df733c21ae0d344a2dec941a3e2a06fefd9
[08/10] gpio: sysfs: export the GPIO directory locally in the gpiochip<id> directory
        https://git.kernel.org/brgl/linux/c/4fa93223e03eea3243db83786f556b6c1494de3e
[09/10] gpio: sysfs: allow disabling the legacy parts of the GPIO sysfs interface
        https://git.kernel.org/brgl/linux/c/e69c6db4cdbc149ff090f1449a114c33ba766dc8
[10/10] gpio: TODO: remove the task for the sysfs rework
        https://git.kernel.org/brgl/linux/c/0c0438d444a7814783099c9028823bff5977e4f0

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@linaro.org>