[PATCH 5.15 061/123] gpiolib: check the ngpios property in core gpiolib code

Greg Kroah-Hartman
2022-12-12T13:31:26Z

From: Bartosz Golaszewski <brgl@bgdev.pl>

[ 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@bgdev.pl>
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Stable-dep-of: ec851b23084b ("gpiolib: fix memory leak in gpiochip_setup_dev()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpio/gpiolib.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

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;
--
2.35.1