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authorMika Westerberg <mika.westerberg@linux.intel.com>2014-03-10 13:54:50 +0100
committerLinus Walleij <linus.walleij@linaro.org>2014-03-13 10:32:18 +0100
commit77c2d7929d7d7f0e391b17f85d2d954912ed0590 (patch)
treecc6672e8cd2f087064a510941fcb2ff3fe73c1e6 /drivers/gpio/gpiolib.h
parentMAINTAINERS: Add Broadcom GPIO maintainer (diff)
downloadlinux-77c2d7929d7d7f0e391b17f85d2d954912ed0590.tar.xz
linux-77c2d7929d7d7f0e391b17f85d2d954912ed0590.zip
gpiolib: Allow GPIO chips to request their own GPIOs
Sometimes it is useful to allow GPIO chips themselves to request GPIOs they own through gpiolib API. One use case is ACPI ASL code that should be able to toggle GPIOs through GPIO operation regions. We can't use gpio_request() because it will pin the module to the kernel forever (it calls try_module_get()). To solve this we move module refcount manipulation to gpiod_request() and let __gpiod_request() handle the actual request. This changes the sequence a bit as now try_module_get() is called outside of gpio_lock (I think this is safe, try_module_get() handles serialization it needs already). Then we provide gpiolib internal functions gpiochip_request/free_own_desc() that do the same as gpio_request() but don't manipulate module refrence count. This allows the GPIO chip driver to request and free descriptors it owns without being pinned to the kernel forever. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/gpio/gpiolib.h')
-rw-r--r--drivers/gpio/gpiolib.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 82be586c1f90..cf092941a9fd 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -43,4 +43,7 @@ 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);
+
#endif /* GPIOLIB_H */