linux-kernel - Re: [PATCH] gpiolib: add GPIO_SET_DEBOUNCE

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Message-ID: <CACRpkdZgkKG04=MmRLjepYY+trGY3fQCx49iFk9aTC4axfaMyw@mail.gmail.com>
Date:   Tue, 28 Apr 2020 12:35:05 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Hector Bujanda <hector.bujanda@...i.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Drew Fustini <drew@...7.com>,
        Kent Gibson <warthog618@...il.com>
Cc:     "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] gpiolib: add GPIO_SET_DEBOUNCE_IOCTL

Hi Hector,

thanks for your patch!

On Sun, Apr 19, 2020 at 2:22 AM Hector Bujanda <hector.bujanda@...i.com> wrote:

> This allows calling gpiod_set_debounce function through char device ioctl.
>
> Signed-off-by: Hector Bujanda <hector.bujanda@...i.com>

(...)
> +/**
> + * struct gpioline_debounce - GPIO line debounce
> + * @line_offset: the local offset on this GPIO device, fill this in when
> + * requesting the line information from the kernel
> + * @debounce_usec: debounce in uSeconds to set for this line
> + */
> +struct gpioline_debounce {
> +       __u32 line_offset;
> +       __u32 debounce_usec;
> +};
(...)
> @@ -154,5 +165,6 @@ struct gpioevent_data {
>  #define GPIO_GET_LINEINFO_IOCTL _IOWR(0xB4, 0x02, struct gpioline_info)
>  #define GPIO_GET_LINEHANDLE_IOCTL _IOWR(0xB4, 0x03, struct gpiohandle_request)
>  #define GPIO_GET_LINEEVENT_IOCTL _IOWR(0xB4, 0x04, struct gpioevent_request)
> +#define GPIO_SET_DEBOUNCE_IOCTL _IOW(0xB4, 0x05, struct gpioline_debounce)

Please do not define a new ioctl for this: since of commit
e588bb1eae31be73fbec2b731be986a7c09635a4
"gpio: add new SET_CONFIG ioctl() to gpio chardev"
by Kent Gibson we have this:

/**
 * struct gpiohandle_config - Configuration for a GPIO handle request
 * @flags: updated flags for the requested GPIO lines, such as
 * GPIOHANDLE_REQUEST_OUTPUT, GPIOHANDLE_REQUEST_ACTIVE_LOW etc, OR:ed
 * together
 * @default_values: if the GPIOHANDLE_REQUEST_OUTPUT is set in flags,
 * this specifies the default output value, should be 0 (low) or
 * 1 (high), anything else than 0 or 1 will be interpreted as 1 (high)
 * @padding: reserved for future use and should be zero filled
 */
struct gpiohandle_config {
        __u32 flags;
        __u8 default_values[GPIOHANDLES_MAX];
        __u32 padding[4]; /* padding for future use */
};

#define GPIOHANDLE_SET_CONFIG_IOCTL _IOWR(0xB4, 0x0a, struct gpiohandle_config)

Setting debounce is just another type of config, so please use Kent's
work as a base for this.

Yours,
Linus Walleij