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    Subject[PATCH 5.17 484/772] gpiolib: of: Introduce hook for missing gpio-ranges
    Date
    From: Stefan Wahren <stefan.wahren@i2se.com>

    [ Upstream commit 3550bba25d5587a701e6edf20e20984d2ee72c78 ]

    Since commit 2ab73c6d8323 ("gpio: Support GPIO controllers without pin-ranges")
    the device tree nodes of GPIO controller need the gpio-ranges property to
    handle gpio-hogs. Unfortunately it's impossible to guarantee that every new
    kernel is shipped with an updated device tree binary.

    In order to provide backward compatibility with those older DTB, we need a
    callback within of_gpiochip_add_pin_range() so the relevant platform driver
    can handle this case.

    Fixes: 2ab73c6d8323 ("gpio: Support GPIO controllers without pin-ranges")
    Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
    Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
    Tested-by: Florian Fainelli <f.fainelli@gmail.com>
    Acked-by: Bartosz Golaszewski <brgl@bgdev.pl>
    Link: https://lore.kernel.org/r/20220409095129.45786-2-stefan.wahren@i2se.com
    Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/gpio/gpiolib-of.c | 5 +++++
    include/linux/gpio/driver.h | 12 ++++++++++++
    2 files changed, 17 insertions(+)

    diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
    index 775a7dadf9a3..1fcb759062c4 100644
    --- a/drivers/gpio/gpiolib-of.c
    +++ b/drivers/gpio/gpiolib-of.c
    @@ -933,6 +933,11 @@ static int of_gpiochip_add_pin_range(struct gpio_chip *chip)
    if (!np)
    return 0;

    + if (!of_property_read_bool(np, "gpio-ranges") &&
    + chip->of_gpio_ranges_fallback) {
    + return chip->of_gpio_ranges_fallback(chip, np);
    + }
    +
    group_names = of_find_property(np, group_names_propname, NULL);

    for (;; index++) {
    diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
    index f8996b46f430..9f0408222f40 100644
    --- a/include/linux/gpio/driver.h
    +++ b/include/linux/gpio/driver.h
    @@ -498,6 +498,18 @@ struct gpio_chip {
    */
    int (*of_xlate)(struct gpio_chip *gc,
    const struct of_phandle_args *gpiospec, u32 *flags);
    +
    + /**
    + * @of_gpio_ranges_fallback:
    + *
    + * Optional hook for the case that no gpio-ranges property is defined
    + * within the device tree node "np" (usually DT before introduction
    + * of gpio-ranges). So this callback is helpful to provide the
    + * necessary backward compatibility for the pin ranges.
    + */
    + int (*of_gpio_ranges_fallback)(struct gpio_chip *gc,
    + struct device_node *np);
    +
    #endif /* CONFIG_OF_GPIO */
    };

    --
    2.35.1


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