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SubjectRe: [PATCH 14/22] gpiolib: make cdev a build option
On Tue, Jun 23, 2020 at 6:02 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> Make the gpiolib-cdev module a build option. This allows the CDEV
> interface to be removed from the kernel to reduce kernel size in
> applications where is it not required, and provides the parent for
> other other CDEV interface specific build options to follow.
>
> Suggested-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> Signed-off-by: Kent Gibson <warthog618@gmail.com>
>
> ---
> drivers/gpio/Kconfig | 16 ++++++++++++++--
> drivers/gpio/Makefile | 2 +-
> drivers/gpio/gpiolib-cdev.h | 15 +++++++++++++++
> 3 files changed, 30 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index c6b5c65c8405..affc1524bc2c 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -66,8 +66,20 @@ config GPIO_SYSFS
>
> This ABI is deprecated. If you want to use GPIO from userspace,
> use the character device /dev/gpiochipN with the appropriate
> - ioctl() operations instead. The character device is always
> - available.
> + ioctl() operations instead.
> +
> +config GPIO_CDEV
> + bool "/dev/gpiochipN (character device interface)"
> + default y
> + help
> + Say Y here to add the character device /dev/gpiochipN interface
> + for GPIOs. The character device allows userspace to control GPIOs
> + using ioctl() operations.
> +
> + Only say N is you are sure that the GPIO character device is not
> + required.
> +
> + If unsure, say Y.
>
> config GPIO_GENERIC
> depends on HAS_IOMEM # Only for IOMEM drivers
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index ef666cfef9d0..45eb09808d12 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -7,8 +7,8 @@ obj-$(CONFIG_GPIOLIB) += gpiolib.o
> obj-$(CONFIG_GPIOLIB) += gpiolib-devres.o
> obj-$(CONFIG_GPIOLIB) += gpiolib-legacy.o
> obj-$(CONFIG_GPIOLIB) += gpiolib-devprop.o
> -obj-$(CONFIG_GPIOLIB) += gpiolib-cdev.o
> obj-$(CONFIG_OF_GPIO) += gpiolib-of.o
> +obj-$(CONFIG_GPIO_CDEV) += gpiolib-cdev.o
> obj-$(CONFIG_GPIO_SYSFS) += gpiolib-sysfs.o
> obj-$(CONFIG_GPIO_ACPI) += gpiolib-acpi.o
>
> diff --git a/drivers/gpio/gpiolib-cdev.h b/drivers/gpio/gpiolib-cdev.h
> index 973578e7ad10..19a4e3d57120 100644
> --- a/drivers/gpio/gpiolib-cdev.h
> +++ b/drivers/gpio/gpiolib-cdev.h
> @@ -5,7 +5,22 @@
>
> #include <linux/device.h>
>
> +#ifdef CONFIG_GPIO_CDEV
> +
> int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt);
> void gpiolib_cdev_unregister(struct gpio_device *gdev);
>
> +#else
> +
> +static inline int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
> +{
> + return 0;
> +}
> +
> +static inline void gpiolib_cdev_unregister(struct gpio_device *gdev)
> +{
> +}
> +
> +#endif /* CONFIG_GPIO_CDEV */
> +
> #endif /* GPIOLIB_CDEV_H */
> --
> 2.27.0
>

I know Linus doesn't like this, but I'm personally in favor of adding
this as long as it's enabled by default.

Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

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