From e69c6db4cdbc149ff090f1449a114c33ba766dc8 Mon Sep 17 00:00:00 2001 From: Bartosz Golaszewski Date: Fri, 4 Jul 2025 14:58:56 +0200 Subject: [PATCH] gpio: sysfs: allow disabling the legacy parts of the GPIO sysfs interface 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 Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-9-9289d8758243@linaro.org Signed-off-by: Bartosz Golaszewski --- 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 6802e549621b2..12bdf6e965f19 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 563e38456c33c..f31adc56bef1e 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 @@ err_remove_groups: 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 @@ err_clear_bit: } 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); } -- 2.47.2