diff options
| -rw-r--r-- | Documentation/gpio/driver.txt | 21 | ||||
| -rw-r--r-- | drivers/gpio/gpiolib.c | 2 | ||||
| -rw-r--r-- | drivers/gpio/gpiolib.h | 3 | ||||
| -rw-r--r-- | include/linux/gpio/driver.h | 3 |
4 files changed, 26 insertions, 3 deletions
diff --git a/Documentation/gpio/driver.txt b/Documentation/gpio/driver.txt index 224dbbcd1804..18790c237977 100644 --- a/Documentation/gpio/driver.txt +++ b/Documentation/gpio/driver.txt @@ -167,3 +167,24 @@ is released: When implementing an irqchip inside a GPIO driver, these two functions should typically be called in the .startup() and .shutdown() callbacks from the irqchip. + + +Requesting self-owned GPIO pins +------------------------------- + +Sometimes it is useful to allow a GPIO chip driver to request its own GPIO +descriptors through the gpiolib API. Using gpio_request() for this purpose +does not help since it pins the module to the kernel forever (it calls +try_module_get()). A GPIO driver can use the following functions instead +to request and free descriptors without being pinned to the kernel forever. + + int gpiochip_request_own_desc(struct gpio_desc *desc, const char *label) + + void gpiochip_free_own_desc(struct gpio_desc *desc) + +Descriptors requested with gpiochip_request_own_desc() must be released with +gpiochip_free_own_desc(). + +These functions must be used with care since they do not affect module use +count. Do not use the functions to request gpio descriptors not owned by the +calling driver. diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 412d64e93cfb..768f0831db18 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -897,6 +897,7 @@ int gpiochip_request_own_desc(struct gpio_desc *desc, const char *label) return __gpiod_request(desc, label); } +EXPORT_SYMBOL_GPL(gpiochip_request_own_desc); /** * gpiochip_free_own_desc - Free GPIO requested by the chip driver @@ -910,6 +911,7 @@ void gpiochip_free_own_desc(struct gpio_desc *desc) if (desc) __gpiod_free(desc); } +EXPORT_SYMBOL_GPL(gpiochip_free_own_desc); /* Drivers MUST set GPIO direction before making get/set calls. In * some cases this is done in early boot, before IRQs are enabled. diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index acbb9335f08c..7fcb645ded4c 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -45,9 +45,6 @@ acpi_get_gpiod_by_index(struct device *dev, int index, } #endif -int gpiochip_request_own_desc(struct gpio_desc *desc, const char *label); -void gpiochip_free_own_desc(struct gpio_desc *desc); - struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np, const char *list_name, int index, enum of_gpio_flags *flags); diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index c66c91682d9e..4c463fb0155e 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -220,6 +220,9 @@ int gpiochip_irqchip_add(struct gpio_chip *gpiochip, #endif /* CONFIG_GPIO_IRQCHIP */ +int gpiochip_request_own_desc(struct gpio_desc *desc, const char *label); +void gpiochip_free_own_desc(struct gpio_desc *desc); + #else /* CONFIG_GPIOLIB */ static inline struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc) |