On 02.06.23 09:49, 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>
Small nitpicks below, but looks good:
Reviewed-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
Thanks for reworking this! Would be great if this can go into next
before release is tagged.
> ---
> 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);
Nitpick: could have changed above to WARN_ON(gc->of_gpio_n_cells < 2)
and dropped the curlies.
> + 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
seperate, 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;
> diff --git a/drivers/of/of_gpio.c b/drivers/of/of_gpio.c
> index 76398f7542..a1fa563a35 100644
> --- a/drivers/of/of_gpio.c
> +++ b/drivers/of/of_gpio.c
> @@ -46,6 +46,44 @@ static void of_gpio_flags_quirks(struct device_node *np,
>
> }
>
> +static struct gpio_chip *of_find_gpiochip_by_xlate(
> + struct of_phandle_args *gpiospec)
> +{
> + struct gpio_chip *chip;
> + struct device *dev;
> +
> + dev = of_find_device_by_node(gpiospec->np);
> + if (!dev) {
> + pr_debug("%s: unable to find device of node %s\n",
> + __func__, gpiospec->np->full_name);
Nitpick: We have %pOF for this.
> + return NULL;
> + }
> +
> + chip = gpio_get_chip_by_dev(dev);
> + if (!chip) {
> + pr_debug("%s: unable to find gpiochip\n", __func__);
> + return NULL;
> + }
> +
> + if (chip->ops->of_xlate &&
> + chip->ops->of_xlate(chip, gpiospec, NULL) >= 0)
> + return chip;
Very nitpicky: inverting this if and turning it into an early-exit
would make code more readable. But if kernel does it that way, that's
fine too.
> +
> + pr_err("%s: failed to execute of_xlate\n", __func__);
> +
> + return NULL;
> +}
> +
> +static int of_xlate_and_get_gpiod_flags(struct gpio_chip *chip,
> + struct of_phandle_args *gpiospec,
> + enum of_gpio_flags *flags)
> +{
> + if (chip->of_gpio_n_cells != gpiospec->args_count)
> + return -EINVAL;
> +
> + return chip->ops->of_xlate(chip, gpiospec, flags);
> +}
> +
> /**
> * of_get_named_gpio_flags() - Get a GPIO number and flags to use with GPIO API
> * @np: device node to get GPIO from
> @@ -61,7 +99,7 @@ int of_get_named_gpio_flags(struct device_node *np, const char *propname,
> int index, enum of_gpio_flags *flags)
> {
> struct of_phandle_args gpiospec;
> - struct device *dev;
> + struct gpio_chip *chip;
> int ret;
>
> ret = of_parse_phandle_with_args(np, propname, "#gpio-cells",
> @@ -72,27 +110,21 @@ int of_get_named_gpio_flags(struct device_node *np, const char *propname,
> return ret;
> }
>
> - dev = of_find_device_by_node(gpiospec.np);
> - if (!dev) {
> - pr_debug("%s: unable to find device of node %s\n",
> - __func__, gpiospec.np->full_name);
> + chip = of_find_gpiochip_by_xlate(&gpiospec);
> + if (!chip) {
> ret = -EPROBE_DEFER;
> goto out;
> }
>
> - ret = gpio_get_num(dev, gpiospec.args[0]);
> - if (ret == -EPROBE_DEFER)
> - goto out;
> + ret = of_xlate_and_get_gpiod_flags(chip, &gpiospec, flags);
> if (ret < 0) {
> pr_err("%s: unable to get gpio num of device %s: %d\n",
> - __func__, dev_name(dev), ret);
> + __func__, dev_name(chip->dev), ret);
> goto out;
> }
>
> - if (flags) {
> - *flags = gpiospec.args[1];
> + if (flags)
> of_gpio_flags_quirks(np, propname, flags, index);
> - }
>
> out:
> of_node_put(gpiospec.np);
> diff --git a/include/gpio.h b/include/gpio.h
> index 5f2c16584c..d82b4505e0 100644
> --- a/include/gpio.h
> +++ b/include/gpio.h
> @@ -177,6 +177,22 @@ struct gpio_ops {
> int (*get_direction)(struct gpio_chip *chip, unsigned offset);
> int (*get)(struct gpio_chip *chip, unsigned offset);
> void (*set)(struct gpio_chip *chip, unsigned offset, int value);
> +
> +#if defined(CONFIG_OF_GPIO)
> + /*
> + * If CONFIG_OF_GPIO is enabled, then all GPIO controllers described in
> + * the device tree automatically may have an OF translation
> + */
> +
> + /**
> + * @of_xlate:
> + *
> + * Callback to translate a device tree GPIO specifier into a chip-
> + * relative GPIO number and flags.
> + */
> + int (*of_xlate)(struct gpio_chip *gc,
> + const struct of_phandle_args *gpiospec, u32 *flags);
> +#endif
> };
>
> struct gpio_chip {
> @@ -185,6 +201,15 @@ struct gpio_chip {
> int base;
> int ngpio;
>
> +#if defined(CONFIG_OF_GPIO)
> + /**
> + * @of_gpio_n_cells:
> + *
> + * Number of cells used to form the GPIO specifier.
> + */
> + unsigned int of_gpio_n_cells;
> +#endif
> +
> struct gpio_ops *ops;
>
> struct list_head list;
--
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