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gpio: sysfs: allow disabling the legacy parts of the GPIO sysfs interface

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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>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-9-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Bartosz Golaszewski 2025-07-04 14:58:56 +02:00
parent 4fa93223e0
commit e69c6db4cd
2 changed files with 50 additions and 0 deletions
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8
drivers/gpio/Kconfig
View file

@ -69,6 +69,14 @@ config GPIO_SYSFS
use the character device /dev/gpiochipN with the appropriate use the character device /dev/gpiochipN with the appropriate
ioctl() operations instead. 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 config GPIO_CDEV
bool "Character device (/dev/gpiochipN) support" if EXPERT bool "Character device (/dev/gpiochipN) support" if EXPERT
default y default y

42
drivers/gpio/gpiolib-sysfs.c
View file

@ -24,6 +24,8 @@
#include "gpiolib.h" #include "gpiolib.h"
#include "gpiolib-sysfs.h" #include "gpiolib-sysfs.h"
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
struct kernfs_node; struct kernfs_node;
#define GPIO_IRQF_TRIGGER_NONE 0 #define GPIO_IRQF_TRIGGER_NONE 0
@ -41,6 +43,8 @@ enum {
GPIO_SYSFS_LINE_CLASS_ATTR_SIZE, GPIO_SYSFS_LINE_CLASS_ATTR_SIZE,
}; };
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
enum { enum {
GPIO_SYSFS_LINE_CHIP_ATTR_DIRECTION = 0, GPIO_SYSFS_LINE_CHIP_ATTR_DIRECTION = 0,
GPIO_SYSFS_LINE_CHIP_ATTR_VALUE, GPIO_SYSFS_LINE_CHIP_ATTR_VALUE,
@ -55,21 +59,26 @@ struct gpiod_data {
struct device *dev; struct device *dev;
struct mutex mutex; struct mutex mutex;
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
struct kernfs_node *value_kn; struct kernfs_node *value_kn;
int irq; int irq;
unsigned char irq_flags; unsigned char irq_flags;
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
bool direction_can_change; bool direction_can_change;
struct kobject *parent; struct kobject *parent;
struct device_attribute dir_attr; struct device_attribute dir_attr;
struct device_attribute val_attr; struct device_attribute val_attr;
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
struct device_attribute edge_attr; struct device_attribute edge_attr;
struct device_attribute active_low_attr; struct device_attribute active_low_attr;
struct attribute *class_attrs[GPIO_SYSFS_LINE_CLASS_ATTR_SIZE]; struct attribute *class_attrs[GPIO_SYSFS_LINE_CLASS_ATTR_SIZE];
struct attribute_group class_attr_group; struct attribute_group class_attr_group;
const struct attribute_group *class_attr_groups[2]; 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 *chip_attrs[GPIO_SYSFS_LINE_CHIP_ATTR_SIZE];
struct attribute_group chip_attr_group; struct attribute_group chip_attr_group;
@ -80,7 +89,9 @@ struct gpiodev_data {
struct list_head exported_lines; struct list_head exported_lines;
struct gpio_device *gdev; struct gpio_device *gdev;
struct device *cdev_id; /* Class device by GPIO device ID */ 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 */ 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; return size;
} }
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
static irqreturn_t gpio_sysfs_irq(int irq, void *priv) static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
{ {
struct gpiod_data *data = 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; 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, static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
int n) int n)
@ -397,6 +410,7 @@ static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
if (!data->direction_can_change) if (!data->direction_can_change)
mode = 0; mode = 0;
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
} else if (strcmp(attr->name, "edge") == 0) { } else if (strcmp(attr->name, "edge") == 0) {
data = container_of(dev_attr, struct gpiod_data, edge_attr); 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 && if (!data->direction_can_change &&
test_bit(FLAG_IS_OUT, &data->desc->flags)) test_bit(FLAG_IS_OUT, &data->desc->flags))
mode = 0; mode = 0;
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
} }
return mode; return mode;
@ -426,6 +441,7 @@ static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
* /ngpio ... matching gpio_chip.ngpio * /ngpio ... matching gpio_chip.ngpio
*/ */
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
static ssize_t base_show(struct device *dev, struct device_attribute *attr, static ssize_t base_show(struct device *dev, struct device_attribute *attr,
char *buf) 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); return sysfs_emit(buf, "%u\n", data->gdev->base);
} }
static DEVICE_ATTR_RO(base); static DEVICE_ATTR_RO(base);
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
static ssize_t label_show(struct device *dev, struct device_attribute *attr, static ssize_t label_show(struct device *dev, struct device_attribute *attr,
char *buf) char *buf)
@ -558,6 +575,7 @@ static struct device_attribute dev_attr_unexport = __ATTR(unexport, 0200,
NULL, NULL,
chip_unexport_store); chip_unexport_store);
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
static struct attribute *gpiochip_attrs[] = { static struct attribute *gpiochip_attrs[] = {
&dev_attr_base.attr, &dev_attr_base.attr,
&dev_attr_label.attr, &dev_attr_label.attr,
@ -565,6 +583,7 @@ static struct attribute *gpiochip_attrs[] = {
NULL, NULL,
}; };
ATTRIBUTE_GROUPS(gpiochip); ATTRIBUTE_GROUPS(gpiochip);
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
static struct attribute *gpiochip_ext_attrs[] = { static struct attribute *gpiochip_ext_attrs[] = {
&dev_attr_label.attr, &dev_attr_label.attr,
@ -575,6 +594,7 @@ static struct attribute *gpiochip_ext_attrs[] = {
}; };
ATTRIBUTE_GROUPS(gpiochip_ext); ATTRIBUTE_GROUPS(gpiochip_ext);
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
/* /*
* /sys/class/gpio/export ... write-only * /sys/class/gpio/export ... write-only
* integer N ... number of GPIO to export (full access) * integer N ... number of GPIO to export (full access)
@ -639,10 +659,13 @@ static struct attribute *gpio_class_attrs[] = {
NULL, NULL,
}; };
ATTRIBUTE_GROUPS(gpio_class); ATTRIBUTE_GROUPS(gpio_class);
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
static const struct class gpio_class = { static const struct class gpio_class = {
.name = "gpio", .name = "gpio",
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
.class_groups = gpio_class_groups, .class_groups = gpio_class_groups,
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
}; };
static int match_gdev(struct device *dev, const void *desc) 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", gpiod_attr_init(&desc_data->dir_attr, "direction",
direction_show, direction_store); direction_show, direction_store);
gpiod_attr_init(&desc_data->val_attr, "value", value_show, value_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->edge_attr, "edge", edge_show, edge_store);
gpiod_attr_init(&desc_data->active_low_attr, "active_low", gpiod_attr_init(&desc_data->active_low_attr, "active_low",
active_low_show, active_low_store); active_low_show, active_low_store);
@ -789,6 +814,7 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
status = -ENODEV; status = -ENODEV;
goto err_unregister_device; goto err_unregister_device;
} }
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
gdev_data = gdev_get_data(gdev); gdev_data = gdev_get_data(gdev);
if (!gdev_data) { if (!gdev_data) {
@ -832,10 +858,12 @@ err_remove_groups:
err_free_name: err_free_name:
kfree(desc_data->chip_attr_group.name); kfree(desc_data->chip_attr_group.name);
err_put_dirent: err_put_dirent:
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
sysfs_put(desc_data->value_kn); sysfs_put(desc_data->value_kn);
err_unregister_device: err_unregister_device:
device_unregister(desc_data->dev); device_unregister(desc_data->dev);
err_free_data: err_free_data:
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
kfree(desc_data); kfree(desc_data);
err_clear_bit: err_clear_bit:
clear_bit(FLAG_EXPORT, &desc->flags); clear_bit(FLAG_EXPORT, &desc->flags);
@ -844,12 +872,14 @@ err_clear_bit:
} }
EXPORT_SYMBOL_GPL(gpiod_export); EXPORT_SYMBOL_GPL(gpiod_export);
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
static int match_export(struct device *dev, const void *desc) static int match_export(struct device *dev, const void *desc)
{ {
struct gpiod_data *data = dev_get_drvdata(dev); struct gpiod_data *data = dev_get_drvdata(dev);
return gpiod_is_equal(data->desc, desc); return gpiod_is_equal(data->desc, desc);
} }
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
/** /**
* gpiod_export_link - create a sysfs link to an exported GPIO node * 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, int gpiod_export_link(struct device *dev, const char *name,
struct gpio_desc *desc) struct gpio_desc *desc)
{ {
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
struct device *cdev; struct device *cdev;
int ret; int ret;
@ -882,6 +913,9 @@ int gpiod_export_link(struct device *dev, const char *name,
put_device(cdev); put_device(cdev);
return ret; return ret;
#else
return -EOPNOTSUPP;
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
} }
EXPORT_SYMBOL_GPL(gpiod_export_link); EXPORT_SYMBOL_GPL(gpiod_export_link);
@ -920,6 +954,7 @@ void gpiod_unexport(struct gpio_desc *desc)
list_del(&desc_data->list); list_del(&desc_data->list);
clear_bit(FLAG_EXPORT, &desc->flags); clear_bit(FLAG_EXPORT, &desc->flags);
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
sysfs_put(desc_data->value_kn); sysfs_put(desc_data->value_kn);
device_unregister(desc_data->dev); device_unregister(desc_data->dev);
@ -929,6 +964,7 @@ void gpiod_unexport(struct gpio_desc *desc)
*/ */
if (desc_data->irq_flags) if (desc_data->irq_flags)
gpio_sysfs_free_irq(desc_data); gpio_sysfs_free_irq(desc_data);
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
sysfs_remove_groups(desc_data->parent, sysfs_remove_groups(desc_data->parent,
desc_data->chip_attr_groups); desc_data->chip_attr_groups);
@ -979,6 +1015,7 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
guard(mutex)(&sysfs_lock); guard(mutex)(&sysfs_lock);
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
/* use chip->base for the ID; it's already known to be unique */ /* use chip->base for the ID; it's already known to be unique */
data->cdev_base = device_create_with_groups(&gpio_class, parent, data->cdev_base = device_create_with_groups(&gpio_class, parent,
MKDEV(0, 0), data, MKDEV(0, 0), data,
@ -990,13 +1027,16 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
kfree(data); kfree(data);
return err; return err;
} }
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
data->cdev_id = device_create_with_groups(&gpio_class, parent, data->cdev_id = device_create_with_groups(&gpio_class, parent,
MKDEV(0, 0), data, MKDEV(0, 0), data,
gpiochip_ext_groups, gpiochip_ext_groups,
"chip%d", gdev->id); "chip%d", gdev->id);
if (IS_ERR(data->cdev_id)) { if (IS_ERR(data->cdev_id)) {
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
device_unregister(data->cdev_base); device_unregister(data->cdev_base);
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
err = PTR_ERR(data->cdev_id); err = PTR_ERR(data->cdev_id);
kfree(data); kfree(data);
return err; return err;
@ -1016,7 +1056,9 @@ void gpiochip_sysfs_unregister(struct gpio_device *gdev)
if (!data) if (!data)
return; return;
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
device_unregister(data->cdev_base); device_unregister(data->cdev_base);
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
device_unregister(data->cdev_id); device_unregister(data->cdev_id);
kfree(data); kfree(data);
} }