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Mon, 30 Jun 2025 05:37:29 -0700 (PDT) From: Bartosz Golaszewski Date: Mon, 30 Jun 2025 14:37:16 +0200 Subject: [PATCH v3 09/10] 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: 7bit Message-Id: <20250630-gpio-sysfs-chip-export-v3-9-b997be9b7137@linaro.org> References: <20250630-gpio-sysfs-chip-export-v3-0-b997be9b7137@linaro.org> In-Reply-To: <20250630-gpio-sysfs-chip-export-v3-0-b997be9b7137@linaro.org> To: Ahmad Fatoum , Kent Gibson , =?utf-8?q?Jan_L=C3=BCbbe?= , Marek Vasut , Geert Uytterhoeven , Linus Walleij , Andy Shevchenko , 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=8085; i=bartosz.golaszewski@linaro.org; h=from:subject:message-id; bh=9hvB6qNzFbQWyGdxmQdVykCyMJnqCezngFxsVt2KrAc=; b=owEBbQKS/ZANAwAKARGnLqAUcddyAcsmYgBoYoT+D6KsRSlzSE5FBFO0IopkSmEtskOdSw8mC 2cpQB6EoiSJAjMEAAEKAB0WIQQWnetsC8PEYBPSx58Rpy6gFHHXcgUCaGKE/gAKCRARpy6gFHHX cgtrEADSpM8n3BF7tT9RoyrQaPzRlrw7xPZ1THM3ExegvocRqZjddo6SzIiIMxMceN1haJVD8Sm bbnISjFSmQf2o99RX5dsU3GamUViEHrfZVQHl82JjXr3r7CMy2tM+THdlzEQOv4RuxlNJuVSQkj skLHDa6ox0d+aAlfwUuB+GSQ3P5F3HMHNWn8ESVsq+hi0CbHi4d7RAe5w2X2NZwtyZNUD1mg/Ur Pcw+IpEmJNjUaqHaGUjt699T7cMNCvpNHGs09VX6M7urlppzuuaYsI8J09tBkKqJ7jRHv/YbkpB 8+Y+C1M4wFNY545Bj4g7QXYl54n9e5GTTguhhzRmTbuVBybkwuXzF9gaNBJ2irdzH3PSA3dFSo8 APpdmU9QBMYOrTdsspvtFjZo72xBE+oc/RHLBEG3rmVR9KUEbhcaNWO/+IPlksHAJO5B5AMqVzq 4fmi1SPJOnllq7gF0LvwHva1mhtYSj166qV1HTdyhtwb2szBh97LZ+CwyH0pHTBupSn3NZ91nwe aQPwtdjA3WVhdimuq+LuVb9foqedAwmxiRWf3AfgykcMa6lAnG1huWRSaffwePoM/Qh9TfW9M2u CR98EoIckw6kmojWE8dpaKWOL4HSnl1eZH6FfZdZYtGiP595ygfLjYaWmEPsa4CFtESpNT7MW8R nO2hcd+EoxMCtGw== 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. Reviewed-by: Linus Walleij Signed-off-by: Bartosz Golaszewski --- 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..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 5b8ea601a3ddf0c8442589db8b1111ecb26e1221..d33fd7eeb82b2dc69861c4fc89613380df7efeea 100644 --- a/drivers/gpio/gpiolib-sysfs.c +++ b/drivers/gpio/gpiolib-sysfs.c @@ -48,7 +48,9 @@ struct gpiod_data { struct device *dev; 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; @@ -69,7 +71,9 @@ 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 */ }; /* @@ -181,7 +185,9 @@ static irqreturn_t gpio_sysfs_irq(int irq, void *priv) { struct gpiod_data *data = priv; +#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); return IRQ_HANDLED; @@ -416,6 +422,7 @@ 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) { @@ -424,6 +431,7 @@ 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) @@ -548,6 +556,7 @@ 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, @@ -555,6 +564,7 @@ static struct attribute *gpiochip_attrs[] = { NULL, }; ATTRIBUTE_GROUPS(gpiochip); +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ static struct attribute *gpiochip_ext_attrs[] = { &dev_attr_label.attr, @@ -565,6 +575,7 @@ 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) @@ -629,10 +640,13 @@ 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) @@ -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 = 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 = -ENODEV; goto err_unregister_device; } +#endif /* CONFIG_GPIO_SYSFS_LEGACY */ gdev_data = gdev_get_data(gdev); if (!gdev_data) { @@ -821,10 +837,12 @@ int gpiod_export(struct gpio_desc *desc, bool direction_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); @@ -833,12 +851,14 @@ 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 @@ -855,6 +875,7 @@ 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; @@ -871,6 +892,9 @@ 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); @@ -909,8 +933,10 @@ 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_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); @@ -967,6 +993,7 @@ 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, @@ -978,13 +1005,16 @@ 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; @@ -1004,7 +1034,9 @@ 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