linux-kernel - Re: [PATCH v8 05/20] gpiolib: make cdev a build option

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Date:   Tue, 15 Sep 2020 13:12:58 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Kent Gibson <warthog618@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v8 05/20] gpiolib: make cdev a build option

On Wed, Sep 9, 2020 at 1:30 PM Kent Gibson <warthog618@...il.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.

In favour of tiny builds!
Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Suggested-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
> Signed-off-by: Kent Gibson <warthog618@...il.com>
> ---
>  drivers/gpio/Kconfig        | 17 +++++++++++++++--
>  drivers/gpio/Makefile       |  2 +-
>  drivers/gpio/gpiolib-cdev.h | 15 +++++++++++++++
>  3 files changed, 31 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 5cfdaf3b004d..e4debd66d71f 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -66,8 +66,21 @@ 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
> +       prompt "Character device (/dev/gpiochipN) support" if EXPERT
> +       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 if 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 4f9abff4f2dc..7c24c8d77068 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 */
> --
> 2.28.0
>


-- 
With Best Regards,
Andy Shevchenko