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gpiolib: provide gpio_device_get_desc()

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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>
This commit is contained in:
Bartosz Golaszewski
2023-09-27 16:29:25 +02:00
parent d62fcd9f18
commit 93548f8bbb
2 changed files with 36 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/gpio/gpiolib.c
+34 -12
View File
@@ -147,27 +147,49 @@ struct gpio_desc *gpio_to_desc(unsigned gpio)
}
EXPORT_SYMBOL_GPL(gpio_to_desc);
/**
* gpiochip_get_desc - get the GPIO descriptor corresponding to the given
* hardware number for this chip
* @gc: GPIO chip
* @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.
*/
/* 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)
{
struct gpio_device *gdev = gc->gpiodev;
return gpio_device_get_desc(gc->gpiodev, hwnum);
}
EXPORT_SYMBOL_GPL(gpiochip_get_desc);
/**
* 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 %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 *
gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum)
{
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
include/linux/gpio/driver.h
+2
View File
@@ -770,6 +770,8 @@ struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *gc,
void gpiochip_free_own_desc(struct gpio_desc *desc);
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);
#ifdef CONFIG_GPIOLIB