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.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
Documentation/ABI/obsolete/sysfs-gpio | 5 +++++
drivers/gpio/gpiolib-sysfs.c | 40 ++++++++++++++++++++++++++++++++++-
2 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/Documentation/ABI/obsolete/sysfs-gpio b/Documentation/ABI/obsolete/sysfs-gpio
index ff694708a3bef787afa42dedf94faf209c44dbf0..c0bb51412a912cefe032c4e84288f99754acb1b5 100644
--- a/Documentation/ABI/obsolete/sysfs-gpio
+++ b/Documentation/ABI/obsolete/sysfs-gpio
@@ -27,6 +27,11 @@ 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
+ /edge ... r/w as: none, falling, rising, both
+ /active-low ... r/w as: 0, 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
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index adf030f74eb163f5d8b1092d00418b84354f923f..37d58009a51333f7d6a8d600dbeaeb333df27ac3 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -47,11 +47,13 @@ struct gpiod_data {
struct mutex mutex;
struct kernfs_node *value_class_node;
+ struct kernfs_node *value_chip_node;
int irq;
unsigned char irq_flags;
bool direction_can_change;
+ struct kobject *parent;
struct device_attribute dir_attr;
struct device_attribute val_attr;
struct device_attribute edge_attr;
@@ -180,6 +182,7 @@ static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
struct gpiod_data *data = priv;
sysfs_notify_dirent(data->value_class_node);
+ kernfs_notify(data->value_chip_node);
return IRQ_HANDLED;
}
@@ -780,13 +783,46 @@ 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;
}
list_add(&desc_data->list, &gdev_data->exported_lines);
+ desc_data->attr_group.name = kasprintf(GFP_KERNEL, "gpio%u",
+ gpio_chip_hwgpio(desc));
+ if (!desc_data->attr_group.name) {
+ status = -ENOMEM;
+ goto err_put_dirent;
+ }
+
+ desc_data->parent = &gdev_data->cdev_id->kobj;
+ status = sysfs_create_groups(desc_data->parent,
+ desc_data->attr_groups);
+ if (status)
+ goto err_free_name;
+
+ char *path __free(kfree) = kasprintf(GFP_KERNEL, "gpio%u/value",
+ gpio_chip_hwgpio(desc));
+ if (!path) {
+ status = -ENOMEM;
+ goto err_remove_groups;
+ }
+
+ desc_data->value_chip_node = kernfs_walk_and_get(desc_data->parent->sd,
+ path);
+ if (!desc_data->value_chip_node) {
+ status = -ENODEV;
+ goto err_remove_groups;
+ }
+
return 0;
+err_remove_groups:
+ sysfs_remove_groups(desc_data->parent, desc_data->attr_groups);
+err_free_name:
+ kfree(desc_data->attr_group.name);
+err_put_dirent:
+ sysfs_put(desc_data->value_class_node);
err_unregister_device:
device_unregister(desc_data->dev);
err_free_data:
@@ -876,6 +912,8 @@ void gpiod_unexport(struct gpio_desc *desc)
clear_bit(FLAG_EXPORT, &desc->flags);
sysfs_put(desc_data->value_class_node);
device_unregister(desc_data->dev);
+ sysfs_remove_groups(desc_data->parent, desc_data->attr_groups);
+ kernfs_put(desc_data->value_chip_node);
/*
* Release irq after deregistration to prevent race with
--
2.48.1Hi Bartosz,
kernel test robot noticed the following build errors:
[auto build test ERROR on cb908f3699fb137e28017a8fdf506c35762b3eb6]
url: https://github.com/intel-lab-lkp/linux/commits/Bartosz-Golaszewski/gpio-sysfs-add-a-parallel-class-device-for-each-GPIO-chip-using-device-IDs/20250623-170412
base: cb908f3699fb137e28017a8fdf506c35762b3eb6
patch link: https://lore.kernel.org/r/20250623-gpio-sysfs-chip-export-v2-7-d592793f8964%40linaro.org
patch subject: [PATCH v2 7/9] gpio: sysfs: export the GPIO directory locally in the gpiochip<id> directory
config: s390-allmodconfig (https://download.01.org/0day-ci/archive/20250624/202506240548.l2wS2XW6-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250624/202506240548.l2wS2XW6-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202506240548.l2wS2XW6-lkp@intel.com/
All errors (new ones prefixed by >>):
>> drivers/gpio/gpiolib-sysfs.c:802:3: error: cannot jump from this goto statement to its label
802 | goto err_free_name;
| ^
drivers/gpio/gpiolib-sysfs.c:804:8: note: jump bypasses initialization of variable with __attribute__((cleanup))
804 | char *path __free(kfree) = kasprintf(GFP_KERNEL, "gpio%u/value",
| ^
drivers/gpio/gpiolib-sysfs.c:795:3: error: cannot jump from this goto statement to its label
795 | goto err_put_dirent;
| ^
drivers/gpio/gpiolib-sysfs.c:804:8: note: jump bypasses initialization of variable with __attribute__((cleanup))
804 | char *path __free(kfree) = kasprintf(GFP_KERNEL, "gpio%u/value",
| ^
drivers/gpio/gpiolib-sysfs.c:786:3: error: cannot jump from this goto statement to its label
786 | goto err_put_dirent;
| ^
drivers/gpio/gpiolib-sysfs.c:804:8: note: jump bypasses initialization of variable with __attribute__((cleanup))
804 | char *path __free(kfree) = kasprintf(GFP_KERNEL, "gpio%u/value",
| ^
drivers/gpio/gpiolib-sysfs.c:780:3: error: cannot jump from this goto statement to its label
780 | goto err_unregister_device;
| ^
drivers/gpio/gpiolib-sysfs.c:804:8: note: jump bypasses initialization of variable with __attribute__((cleanup))
804 | char *path __free(kfree) = kasprintf(GFP_KERNEL, "gpio%u/value",
| ^
drivers/gpio/gpiolib-sysfs.c:773:3: error: cannot jump from this goto statement to its label
773 | goto err_free_data;
| ^
drivers/gpio/gpiolib-sysfs.c:804:8: note: jump bypasses initialization of variable with __attribute__((cleanup))
804 | char *path __free(kfree) = kasprintf(GFP_KERNEL, "gpio%u/value",
| ^
drivers/gpio/gpiolib-sysfs.c:733:3: error: cannot jump from this goto statement to its label
733 | goto err_clear_bit;
| ^
drivers/gpio/gpiolib-sysfs.c:804:8: note: jump bypasses initialization of variable with __attribute__((cleanup))
804 | char *path __free(kfree) = kasprintf(GFP_KERNEL, "gpio%u/value",
| ^
drivers/gpio/gpiolib-sysfs.c:727:3: error: cannot jump from this goto statement to its label
727 | goto err_clear_bit;
| ^
drivers/gpio/gpiolib-sysfs.c:804:8: note: jump bypasses initialization of variable with __attribute__((cleanup))
804 | char *path __free(kfree) = kasprintf(GFP_KERNEL, "gpio%u/value",
| ^
7 errors generated.
vim +802 drivers/gpio/gpiolib-sysfs.c
677
678 /**
679 * gpiod_export - export a GPIO through sysfs
680 * @desc: GPIO to make available, already requested
681 * @direction_may_change: true if userspace may change GPIO direction
682 * Context: arch_initcall or later
683 *
684 * When drivers want to make a GPIO accessible to userspace after they
685 * have requested it -- perhaps while debugging, or as part of their
686 * public interface -- they may use this routine. If the GPIO can
687 * change direction (some can't) and the caller allows it, userspace
688 * will see "direction" sysfs attribute which may be used to change
689 * the gpio's direction. A "value" attribute will always be provided.
690 *
691 * Returns:
692 * 0 on success, or negative errno on failure.
693 */
694 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
695 {
696 struct gpiodev_data *gdev_data;
697 struct gpiod_data *desc_data;
698 struct gpio_device *gdev;
699 struct attribute **attrs;
700 int status;
701
702 /* can't export until sysfs is available ... */
703 if (!class_is_registered(&gpio_class)) {
704 pr_debug("%s: called too early!\n", __func__);
705 return -ENOENT;
706 }
707
708 if (!desc) {
709 pr_debug("%s: invalid gpio descriptor\n", __func__);
710 return -EINVAL;
711 }
712
713 CLASS(gpio_chip_guard, guard)(desc);
714 if (!guard.gc)
715 return -ENODEV;
716
717 if (test_and_set_bit(FLAG_EXPORT, &desc->flags))
718 return -EPERM;
719
720 gdev = desc->gdev;
721
722 guard(mutex)(&sysfs_lock);
723
724 if (!test_bit(FLAG_REQUESTED, &desc->flags)) {
725 gpiod_dbg(desc, "%s: unavailable (not requested)\n", __func__);
726 status = -EPERM;
727 goto err_clear_bit;
728 }
729
730 desc_data = kzalloc(sizeof(*desc_data), GFP_KERNEL);
731 if (!desc_data) {
732 status = -ENOMEM;
733 goto err_clear_bit;
734 }
735
736 desc_data->desc = desc;
737 mutex_init(&desc_data->mutex);
738 if (guard.gc->direction_input && guard.gc->direction_output)
739 desc_data->direction_can_change = direction_may_change;
740 else
741 desc_data->direction_can_change = false;
742
743 gpiod_attr_init(&desc_data->dir_attr, "direction",
744 direction_show, direction_store);
745 gpiod_attr_init(&desc_data->val_attr, "value", value_show, value_store);
746 gpiod_attr_init(&desc_data->edge_attr, "edge", edge_show, edge_store);
747 gpiod_attr_init(&desc_data->active_low_attr, "active_low",
748 active_low_show, active_low_store);
749
750 attrs = desc_data->attrs;
751 desc_data->attr_group.is_visible = gpio_is_visible;
752 attrs[GPIO_SYSFS_LINE_ATTR_DIRECTION] = &desc_data->dir_attr.attr;
753 attrs[GPIO_SYSFS_LINE_ATTR_VALUE] = &desc_data->val_attr.attr;
754 attrs[GPIO_SYSFS_LINE_ATTR_EDGE] = &desc_data->edge_attr.attr;
755 attrs[GPIO_SYSFS_LINE_ATTR_ACTIVE_LOW] =
756 &desc_data->active_low_attr.attr;
757
758 desc_data->attr_group.attrs = desc_data->attrs;
759 desc_data->attr_groups[0] = &desc_data->attr_group;
760
761 /*
762 * Note: we need to continue passing desc_data here as there's still
763 * at least one known user of gpiod_export_link() in the tree. This
764 * function still uses class_find_device() internally.
765 */
766 desc_data->dev = device_create_with_groups(&gpio_class, &gdev->dev,
767 MKDEV(0, 0), desc_data,
768 desc_data->attr_groups,
769 "gpio%u",
770 desc_to_gpio(desc));
771 if (IS_ERR(desc_data->dev)) {
772 status = PTR_ERR(desc_data->dev);
773 goto err_free_data;
774 }
775
776 desc_data->value_class_node = sysfs_get_dirent(desc_data->dev->kobj.sd,
777 "value");
778 if (!desc_data->value_class_node) {
779 status = -ENODEV;
780 goto err_unregister_device;
781 }
782
783 gdev_data = gdev_get_data(gdev);
784 if (!gdev_data) {
785 status = -ENODEV;
786 goto err_put_dirent;
787 }
788
789 list_add(&desc_data->list, &gdev_data->exported_lines);
790
791 desc_data->attr_group.name = kasprintf(GFP_KERNEL, "gpio%u",
792 gpio_chip_hwgpio(desc));
793 if (!desc_data->attr_group.name) {
794 status = -ENOMEM;
795 goto err_put_dirent;
796 }
797
798 desc_data->parent = &gdev_data->cdev_id->kobj;
799 status = sysfs_create_groups(desc_data->parent,
800 desc_data->attr_groups);
801 if (status)
> 802 goto err_free_name;
803
804 char *path __free(kfree) = kasprintf(GFP_KERNEL, "gpio%u/value",
805 gpio_chip_hwgpio(desc));
806 if (!path) {
807 status = -ENOMEM;
808 goto err_remove_groups;
809 }
810
811 desc_data->value_chip_node = kernfs_walk_and_get(desc_data->parent->sd,
812 path);
813 if (!desc_data->value_chip_node) {
814 status = -ENODEV;
815 goto err_remove_groups;
816 }
817
818 return 0;
819
820 err_remove_groups:
821 sysfs_remove_groups(desc_data->parent, desc_data->attr_groups);
822 err_free_name:
823 kfree(desc_data->attr_group.name);
824 err_put_dirent:
825 sysfs_put(desc_data->value_class_node);
826 err_unregister_device:
827 device_unregister(desc_data->dev);
828 err_free_data:
829 kfree(desc_data);
830 err_clear_bit:
831 clear_bit(FLAG_EXPORT, &desc->flags);
832 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
833 return status;
834 }
835 EXPORT_SYMBOL_GPL(gpiod_export);
836
--
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