Patch "gpiolib: check the 'ngpios' property in core gpiolib code" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    gpiolib: check the 'ngpios' property in core gpiolib code

to the 5.15-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-check-the-ngpios-property-in-core-gpiolib-co.patch
and it can be found in the queue-5.15 subdirectory.

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



commit 41304b9a6babb076aea3507da2bf2210e7dbab68
Author: Bartosz Golaszewski <brgl@xxxxxxxx>
Date:   Thu Dec 2 14:40:34 2021 +0100

    gpiolib: check the 'ngpios' property in core gpiolib code
    
    [ Upstream commit 9dbd1ab20509e85cd3fac9479a00c59e83c08196 ]
    
    Several drivers read the 'ngpios' device property on their own, but
    since it's defined as a standard GPIO property in the device tree bindings
    anyway, it's a good candidate for generalization. If the driver didn't
    set its gc->ngpio, try to read the 'ngpios' property from the GPIO
    device's firmware node before bailing out.
    
    Signed-off-by: Bartosz Golaszewski <brgl@xxxxxxxx>
    Suggested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
    Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
    Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
    Stable-dep-of: ec851b23084b ("gpiolib: fix memory leak in gpiochip_setup_dev()")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index a87c4cd94f7a..b7b5fe151e1a 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -599,6 +599,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 	int base = gc->base;
 	unsigned int i;
 	int ret = 0;
+	u32 ngpios;
 
 	/*
 	 * First: allocate and populate the internal stat container, and
@@ -646,6 +647,26 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 		goto err_free_dev_name;
 	}
 
+	/*
+	 * Try the device properties if the driver didn't supply the number
+	 * of GPIO lines.
+	 */
+	if (gc->ngpio == 0) {
+		ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios);
+		if (ret == -ENODATA)
+			/*
+			 * -ENODATA means that there is no property found and
+			 * we want to issue the error message to the user.
+			 * Besides that, we want to return different error code
+			 * to state that supplied value is not valid.
+			 */
+			ngpios = 0;
+		else if (ret)
+			goto err_free_descs;
+
+		gc->ngpio = ngpios;
+	}
+
 	if (gc->ngpio == 0) {
 		chip_err(gc, "tried to insert a GPIO chip with zero lines\n");
 		ret = -EINVAL;