Commit f7d4ad98 authored by Guenter Roeck's avatar Guenter Roeck Committed by Linus Walleij
Browse files

gpiolib: Export gpiochip_request_own_desc and gpiochip_free_own_desc 



Both functions were introduced to let gpio drivers request their own
gpio pins. Without exporting the functions, this can however only be
used by gpio drivers built into the kernel.

Secondary impact is that the functions can not currently be used by
platform initialization code associated with the gpio-pca953x driver.
This code permits auto-export of gpio pins through platform data, but
if this functionality is used, the module can no longer be unloaded due
to the problem solved with the introduction of gpiochip_request_own_desc
and gpiochip_free_own_desc.

Export both function so they can be used from modules and from
platform initialization code.

Reviewed-by: default avatarAlexandre Courbot <acourbot@nvidia.com>
Reviewed-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent d82da797

Documentation/gpio/driver.txt

+21 −0
Original line number Original line Diff line number Diff line
@@ -167,3 +167,24 @@ is released: 
When implementing an irqchip inside a GPIO driver, these two functions should

When implementing an irqchip inside a GPIO driver, these two functions should

typically be called in the .startup() and .shutdown() callbacks from the

typically be called in the .startup() and .shutdown() callbacks from the

irqchip.

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.

drivers/gpio/gpiolib.c

+2 −0
Original line number Original line Diff line number Diff line
@@ -897,6 +897,7 @@ int gpiochip_request_own_desc(struct gpio_desc *desc, const char *label) 




	return __gpiod_request(desc, label);

	return __gpiod_request(desc, label);

}

}

EXPORT_SYMBOL_GPL(gpiochip_request_own_desc);





/**

/**

 * gpiochip_free_own_desc - Free GPIO requested by the chip driver

 * 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)

	if (desc)

		__gpiod_free(desc);

		__gpiod_free(desc);

}

}

EXPORT_SYMBOL_GPL(gpiochip_free_own_desc);





/* Drivers MUST set GPIO direction before making get/set calls.  In

/* Drivers MUST set GPIO direction before making get/set calls.  In

 * some cases this is done in early boot, before IRQs are enabled.

 * some cases this is done in early boot, before IRQs are enabled.

drivers/gpio/gpiolib.h

+0 −3
Original line number Original line Diff line number Diff line
@@ -45,9 +45,6 @@ acpi_get_gpiod_by_index(struct device *dev, int index, 
}

}

#endif

#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,

struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np,

		   const char *list_name, int index, enum of_gpio_flags *flags);

		   const char *list_name, int index, enum of_gpio_flags *flags);

include/linux/gpio/driver.h

+3 −0
Original line number Original line Diff line number Diff line
@@ -220,6 +220,9 @@ int gpiochip_irqchip_add(struct gpio_chip *gpiochip, 




#endif /* CONFIG_GPIO_IRQCHIP */

#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 */

#else /* CONFIG_GPIOLIB */





static inline struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)

static inline struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)

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