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-rw-r--r--Documentation/gpio/driver.txt21
-rw-r--r--drivers/gpio/gpiolib.c2
-rw-r--r--drivers/gpio/gpiolib.h3
-rw-r--r--include/linux/gpio/driver.h3
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)

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