gpio: Export devm_gpiod_get_from_of_node() for consumers

We have been holding back on adding an API for fetching GPIO handles
directly from device nodes, strongly preferring to get it from the
spawn devices instead.

The fwnode interface however already contains an API for doing this,
as it is used for opaque device tree nodes or ACPI nodes for getting
handles to LEDs and keys that use GPIO: those are specified as one
child per LED/key in the device tree and are not individual devices.

However regulators present a special problem as they already have
helper functions to traverse the device tree from a regulator node
and two levels down to fill in data, and as it already traverses
GPIO nodes in its own way, and already holds a pointer to each
regulators device tree node, it makes most sense to export an
API to fetch the GPIO descriptor directly from the node.

We only support the devm_* version for now, hopefully no non-devres
version will be needed.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 6e9228b94437..0ae9f991ede1 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -193,6 +193,12 @@ void gpiod_set_array_value_complex(bool raw, bool can_sleep,
 				   struct gpio_desc **desc_array,
 				   int *value_array);
 
+/* This is just passed between gpiolib and devres */
+struct gpio_desc *gpiod_get_from_of_node(struct device_node *node,
+					 const char *propname, int index,
+					 enum gpiod_flags dflags,
+					 const char *label);
+
 extern struct spinlock gpio_lock;
 extern struct list_head gpio_devices;