Hi Marco,
On Fri, Jun 02, 2023 at 09:49:21AM +0200, Marco Felsch wrote:
> The of_xlate function can be used to by drivers which need a other gpio
> encoding than:
>
> gpio = <&phandle gpio-nr gpio-flags>;
>
> The of_xlate code is as close as possible to the kernel counter part
> which makes it easier to add 'struct gpio_desc' support later on.
>
> Signed-off-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx>
> ---
> drivers/gpio/gpiolib.c | 51 ++++++++++++++++++++++++++++++++++++++
> drivers/of/of_gpio.c | 56 +++++++++++++++++++++++++++++++++---------
> include/gpio.h | 25 +++++++++++++++++++
> 3 files changed, 120 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index d1087aa583..ab9a0e30be 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -592,6 +592,43 @@ static int of_gpiochip_set_names(struct gpio_chip *chip)
> return 0;
> }
>
> +/**
> + * of_gpio_simple_xlate - translate gpiospec to the GPIO number and flags
> + * @gc: pointer to the gpio_chip structure
> + * @gpiospec: GPIO specifier as found in the device tree
> + * @flags: a flags pointer to fill in
> + *
> + * This is simple translation function, suitable for the most 1:1 mapped
> + * GPIO chips. This function performs only one sanity check: whether GPIO
> + * is less than ngpios (that is specified in the gpio_chip).
> + */
> +static int of_gpio_simple_xlate(struct gpio_chip *gc,
> + const struct of_phandle_args *gpiospec,
> + u32 *flags)
> +{
> + /*
> + * We're discouraging gpio_cells < 2, since that way you'll have to
> + * write your own xlate function (that will have to retrieve the GPIO
> + * number and the flags from a single gpio cell -- this is possible,
> + * but not recommended).
> + */
> + if (gc->of_gpio_n_cells < 2) {
> + WARN_ON(1);
> + return -EINVAL;
> + }
> +
> + if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
> + return -EINVAL;
> +
> + if (gpiospec->args[0] >= gc->ngpio)
> + return -EINVAL;
> +
> + if (flags)
> + *flags = gpiospec->args[1];
> +
> + return gc->base + gpiospec->args[0];
> +}
> +
> static int of_gpiochip_add(struct gpio_chip *chip)
> {
> struct device_node *np;
> @@ -601,6 +638,20 @@ static int of_gpiochip_add(struct gpio_chip *chip)
> if (!np)
> return 0;
>
> + if (!chip->ops->of_xlate)
> + chip->ops->of_xlate = of_gpio_simple_xlate;
> +
> + /*
> + * Seperate check since the 'struct gpio_ops' is alawys the same for
typos: s/Seperate/Separate/ and s/alawys/always/
> + * every 'struct gpio_chip' of the same instance (e.g. 'struct
> + * imx_gpio_chip').
> + */
> + if (chip->ops->of_xlate == of_gpio_simple_xlate)
> + chip->of_gpio_n_cells = 2;
> +
> + if (chip->of_gpio_n_cells > MAX_PHANDLE_ARGS)
> + return -EINVAL;
> +
> ret = of_gpiochip_set_names(chip);
> if (ret)
> return ret;
Thanks :)
