Patch "gpiolib: of: Introduce hook for missing gpio-ranges" has been added to the 5.18-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    gpiolib: of: Introduce hook for missing gpio-ranges

to the 5.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     gpiolib-of-introduce-hook-for-missing-gpio-ranges.patch
and it can be found in the queue-5.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit dde603cbd86ada8c2a36ee536a133b6a317b242e
Author: Stefan Wahren <stefan.wahren@xxxxxxxx>
Date:   Sat Apr 9 11:51:28 2022 +0200

    gpiolib: of: Introduce hook for missing gpio-ranges
    
    [ 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@xxxxxxxx>
    Reviewed-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
    Tested-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
    Acked-by: Bartosz Golaszewski <brgl@xxxxxxxx>
    Link: https://lore.kernel.org/r/20220409095129.45786-2-stefan.wahren@xxxxxxxx
    Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 7e5e51d49d09..6dec81b1f24b 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -931,6 +931,11 @@ 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 874aabd270c9..48d03eb4e5d8 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -501,6 +501,18 @@ 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 */
 };