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authorBartosz Golaszewski <bartosz.golaszewski@linaro.org>2023-09-27 17:29:25 +0300
committerBartosz Golaszewski <bartosz.golaszewski@linaro.org>2023-10-04 14:29:56 +0300
commit93548f8bbbbf5b62dbd37c8f61a037a06666787b (patch)
treec34338852cee00c40de2e10d8d1d41d306de374f /drivers/gpio/gpiolib.c
parentd62fcd9f1897d587f8f9db3f77ccae8797a44b5d (diff)
downloadlinux-93548f8bbbbf5b62dbd37c8f61a037a06666787b.tar.xz
gpiolib: provide gpio_device_get_desc()
Getting the GPIO descriptor directly from the gpio_chip struct is dangerous as we don't take the reference to the underlying GPIO device. In order to start working towards removing gpiochip_get_desc(), let's provide a safer variant that works with an existing reference to struct gpio_device. Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/gpio/gpiolib.c')
-rw-r--r--drivers/gpio/gpiolib.c40
1 files changed, 31 insertions, 9 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 0a41f6ee8d33..f4fdf620ca74 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -147,27 +147,49 @@ struct gpio_desc *gpio_to_desc(unsigned gpio)
}
EXPORT_SYMBOL_GPL(gpio_to_desc);
+/* This function is deprecated and will be removed soon, don't use. */
+struct gpio_desc *gpiochip_get_desc(struct gpio_chip *gc,
+ unsigned int hwnum)
+{
+ return gpio_device_get_desc(gc->gpiodev, hwnum);
+}
+EXPORT_SYMBOL_GPL(gpiochip_get_desc);
+
/**
- * gpiochip_get_desc - get the GPIO descriptor corresponding to the given
- * hardware number for this chip
- * @gc: GPIO chip
+ * gpio_device_get_desc() - get the GPIO descriptor corresponding to the given
+ * hardware number for this GPIO device
+ * @gdev: GPIO device to get the descriptor from
* @hwnum: hardware number of the GPIO for this chip
*
* Returns:
- * A pointer to the GPIO descriptor or ``ERR_PTR(-EINVAL)`` if no GPIO exists
- * in the given chip for the specified hardware number.
+ * A pointer to the GPIO descriptor or %EINVAL if no GPIO exists in the given
+ * chip for the specified hardware number or %ENODEV if the underlying chip
+ * already vanished.
+ *
+ * The reference count of struct gpio_device is *NOT* increased like when the
+ * GPIO is being requested for exclusive usage. It's up to the caller to make
+ * sure the GPIO device will stay alive together with the descriptor returned
+ * by this function.
*/
-struct gpio_desc *gpiochip_get_desc(struct gpio_chip *gc,
- unsigned int hwnum)
+struct gpio_desc *
+gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum)
{
- struct gpio_device *gdev = gc->gpiodev;
+ struct gpio_chip *gc;
+
+ /*
+ * FIXME: This will be locked once we protect gdev->chip everywhere
+ * with SRCU.
+ */
+ gc = gdev->chip;
+ if (!gc)
+ return ERR_PTR(-ENODEV);
if (hwnum >= gdev->ngpio)
return ERR_PTR(-EINVAL);
return &gdev->descs[hwnum];
}
-EXPORT_SYMBOL_GPL(gpiochip_get_desc);
+EXPORT_SYMBOL_GPL(gpio_device_get_desc);
/**
* desc_to_gpio - convert a GPIO descriptor to the integer namespace