gpiolib: add Linux-like gpiod_get() helper

Many Linux drivers use [devm_]gpiod_get to get appropriately configured
GPIO descriptors out with little code. Make porting such Linux code
easier by providing a semi-compatible gpiod_get function. Main
differences:

 - It returns a gpio index, so it can be passed to any gpio_ function
 - It's device-tree only, so it should only be used from drivers
   that themselves probe from device tree.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Link: https://lore.pengutronix.de/20210410103511.2073504-1-ahmad@a3f.at

1 files changed, 26 insertions, 0 deletions

diff --git a/include/gpiod.h b/include/gpiod.h
new file mode 100644
index 0000000000..c8b2cd47a3
--- /dev/null
+++ b/include/gpiod.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __GPIOD_H_
+#define __GPIOD_H_
+
+#include <gpio.h>
+#include <of_gpio.h>
+
+/**
+ * Optional flags that can be passed to one of gpiod_* to configure direction
+ * and output value. These values cannot be OR'd.
+ */
+enum gpiod_flags {
+	GPIOD_ASIS	= 0,
+	GPIOD_IN	= GPIOF_IN,
+	/*
+	 * To change this later to a different logic level (i.e. taking
+	 * active low into account), use gpio_direction_active()
+	 */
+	GPIOD_OUT_LOW	= GPIOF_OUT_INIT_INACTIVE,
+	GPIOD_OUT_HIGH	= GPIOF_OUT_INIT_ACTIVE,
+};
+
+/* returned gpio descriptor can be passed to any normal gpio_* function */
+int gpiod_get(struct device_d *dev, const char *_con_id, enum gpiod_flags flags);
+
+#endif