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Mon, 23 Jun 2025 02:00:20 -0700 (PDT) From: Bartosz Golaszewski Date: Mon, 23 Jun 2025 10:59:56 +0200 Subject: [PATCH v2 8/9] gpio: sysfs: allow disabling the legacy parts of the GPIO sysfs interface Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250623-gpio-sysfs-chip-export-v2-8-d592793f8964@linaro.org> References: <20250623-gpio-sysfs-chip-export-v2-0-d592793f8964@linaro.org> In-Reply-To: <20250623-gpio-sysfs-chip-export-v2-0-d592793f8964@linaro.org> To: Ahmad Fatoum , Kent Gibson , =?utf-8?q?Jan_L=C3=BCbbe?= , Marek Vasut , Geert Uytterhoeven , Linus Walleij , Bartosz Golaszewski Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=8023; i=bartosz.golaszewski@linaro.org; h=from:subject:message-id; bh=2di3W2yHM6i5t7LwlUeew0hS2H4VmaMxC0/5eiN8mL0=; b=owEBbQKS/ZANAwAKARGnLqAUcddyAcsmYgBoWReaRzZCBOEPZ+cr1jQF9rq/zdO1N7t39cpCp /lw3/F3eQ6JAjMEAAEKAB0WIQQWnetsC8PEYBPSx58Rpy6gFHHXcgUCaFkXmgAKCRARpy6gFHHX cuJQD/9CRL6ndRy7Z43UUrz4mA1YKdV5BbivNqpcdvytQgmNpXEgdXg9je6ot436b/H0ivUd+ZJ y0EDUN0bGezYbKp6Cs4XurE/x/ZlhVqvD8rRPEGioP7xhVXtVonGmnAPw2CUdMzQX8bTwTNZuzu ZdHxQ/6MYI95+g7r/yRAuJdfb+JflNLRU7DzJ5gINmqjwLEmkGnm6bUf2XaifWMAhE46AlzKSz0 H6MDQAmo/X41nb1uj1muSNWvsZhtUJ1ahcRJx0ZFE9VdKq3zv/YOLYQplhFJ/RsMtlXam1tQifN TkAngA5CB0hG5UGGwyrpBGPLqCpRQBl2IVmmNo49AiJ/W/dUU/upKWpSckZlsXV9uYZYfKxrkI3 5m7mGfrsCUDc6uUfc7Sf1PNzJ5vQ9jeMPRbgSs3R6kbAeE+NjhQ12nzTO6mEOPvWb3C2NLWtLug 9qnauv6FI7kHdSVXXZ6ovyHz8vKRPMTtVGDalh0vgoBsA7Jo03hzUjYoHdGr5cZzpE+cbW1l/3f zrVAHd+WKHUFS6MZH5IB4K7tqpClcXySD6rbLpbGb4J24drF3oZpVkFhNa1FAWBxv/GZ/blKlYS GaWfEM+ol316qWXYXfAUt8+3U7Lrku3L2H5dlPcOO0Z+v+ns75QH2q9Ei8sYFzO8Z6oatgqy4it /+1hiEFCF1zkHgA== X-Developer-Key: i=bartosz.golaszewski@linaro.org; a=openpgp; fpr=169DEB6C0BC3C46013D2C79F11A72EA01471D772 From: Bartosz Golaszewski 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. Signed-off-by: Bartosz Golaszewski Reviewed-by: Linus Walleij --- drivers/gpio/Kconfig | 8 ++++++++ drivers/gpio/gpiolib-sysfs.c | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+) diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index 44f922e10db2f8dcbdacf79ccd27b0fd9cd93564..d040fdd95ee4b19851057fbedbb= 023f277149c9c 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. =20 +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 37d58009a51333f7d6a8d600dbeaeb333df27ac3..0e7605fee3bd9edbe4e90d8e466= 742df11a8d579 100644 --- a/drivers/gpio/gpiolib-sysfs.c +++ b/drivers/gpio/gpiolib-sysfs.c @@ -46,7 +46,9 @@ struct gpiod_data { struct device *dev; =20 struct mutex mutex; +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) struct kernfs_node *value_class_node; +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ struct kernfs_node *value_chip_node; int irq; unsigned char irq_flags; @@ -67,7 +69,9 @@ struct gpiod_data { =20 struct gpiodev_data { struct gpio_device *gdev; +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) struct device *cdev_base; /* Class device by GPIO base */ +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ struct device *cdev_id; /* Class device by GPIO device ID */ struct list_head exported_lines; }; @@ -181,7 +185,9 @@ static irqreturn_t gpio_sysfs_irq(int irq, void *priv) { struct gpiod_data *data =3D priv; =20 +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) sysfs_notify_dirent(data->value_class_node); +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ kernfs_notify(data->value_chip_node); =20 return IRQ_HANDLED; @@ -416,6 +422,7 @@ static umode_t gpio_is_visible(struct kobject *kobj, st= ruct attribute *attr, * /ngpio ... matching gpio_chip.ngpio */ =20 +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) static ssize_t base_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -424,6 +431,7 @@ static ssize_t base_show(struct device *dev, struct dev= ice_attribute *attr, return sysfs_emit(buf, "%u\n", data->gdev->base); } static DEVICE_ATTR_RO(base); +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ =20 static ssize_t label_show(struct device *dev, struct device_attribute *att= r, char *buf) @@ -548,6 +556,7 @@ static struct device_attribute dev_attr_unexport =3D __= ATTR(unexport, 0200, NULL, chip_unexport_store); =20 +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) static struct attribute *gpiochip_attrs[] =3D { &dev_attr_base.attr, &dev_attr_label.attr, @@ -555,6 +564,7 @@ static struct attribute *gpiochip_attrs[] =3D { NULL, }; ATTRIBUTE_GROUPS(gpiochip); +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ =20 static struct attribute *gpiochip_ext_attrs[] =3D { &dev_attr_label.attr, @@ -565,6 +575,7 @@ static struct attribute *gpiochip_ext_attrs[] =3D { }; ATTRIBUTE_GROUPS(gpiochip_ext); =20 +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) /* * /sys/class/gpio/export ... write-only * integer N ... number of GPIO to export (full access) @@ -629,10 +640,13 @@ static struct attribute *gpio_class_attrs[] =3D { NULL, }; ATTRIBUTE_GROUPS(gpio_class); +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ =20 static const struct class gpio_class =3D { .name =3D "gpio", +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) .class_groups =3D gpio_class_groups, +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ }; =20 static int match_gdev(struct device *dev, const void *desc) @@ -763,6 +777,7 @@ int gpiod_export(struct gpio_desc *desc, bool direction= _may_change) * at least one known user of gpiod_export_link() in the tree. This * function still uses class_find_device() internally. */ +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) desc_data->dev =3D device_create_with_groups(&gpio_class, &gdev->dev, MKDEV(0, 0), desc_data, desc_data->attr_groups, @@ -779,6 +794,7 @@ int gpiod_export(struct gpio_desc *desc, bool direction= _may_change) status =3D -ENODEV; goto err_unregister_device; } +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ =20 gdev_data =3D gdev_get_data(gdev); if (!gdev_data) { @@ -822,10 +838,12 @@ int gpiod_export(struct gpio_desc *desc, bool directi= on_may_change) err_free_name: kfree(desc_data->attr_group.name); err_put_dirent: +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) sysfs_put(desc_data->value_class_node); 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); @@ -834,12 +852,14 @@ int gpiod_export(struct gpio_desc *desc, bool directi= on_may_change) } EXPORT_SYMBOL_GPL(gpiod_export); =20 +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) static int match_export(struct device *dev, const void *desc) { struct gpiod_data *data =3D dev_get_drvdata(dev); =20 return data->desc =3D=3D desc; } +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ =20 /** * gpiod_export_link - create a sysfs link to an exported GPIO node @@ -856,6 +876,7 @@ 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; =20 @@ -872,6 +893,9 @@ int gpiod_export_link(struct device *dev, const char *n= ame, put_device(cdev); =20 return ret; +#else + return -EOPNOTSUPP; +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ } EXPORT_SYMBOL_GPL(gpiod_export_link); =20 @@ -910,8 +934,10 @@ void gpiod_unexport(struct gpio_desc *desc) =20 list_del(&desc_data->list); clear_bit(FLAG_EXPORT, &desc->flags); +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) sysfs_put(desc_data->value_class_node); device_unregister(desc_data->dev); +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ sysfs_remove_groups(desc_data->parent, desc_data->attr_groups); kernfs_put(desc_data->value_chip_node); =20 @@ -968,6 +994,7 @@ int gpiochip_sysfs_register(struct gpio_device *gdev) =20 guard(mutex)(&sysfs_lock); =20 +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) /* use chip->base for the ID; it's already known to be unique */ data->cdev_base =3D device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), data, @@ -979,13 +1006,16 @@ int gpiochip_sysfs_register(struct gpio_device *gdev) kfree(data); return err; } +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ =20 data->cdev_id =3D 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 */ kfree(data); return PTR_ERR(data->cdev_id); } @@ -1004,7 +1034,9 @@ void gpiochip_sysfs_unregister(struct gpio_device *gd= ev) if (!data) return; =20 +#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY) device_unregister(data->cdev_base); +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ device_unregister(data->cdev_id); kfree(data); } --=20 2.48.1