gpio: add ops to set dir flags

Add the ops for GPIO driver set_dir_flags() to set the dir flags.
The user can update the direction and configuration
of each GPIO with a only call to dm_gpio_set_dir_flags() or
dm_gpio_set_dir() and respecting the configuration provided by
device tree (saved in desc->flags).

When these optional ops are absent, the gpio uclass use the mandatory
ops (direction_output, direction_input, get_value) and desc->flags
to manage only the main dir flags:
- GPIOD_IS_IN
- GPIOD_IS_OUT
- GPIOD_IS_OUT_ACTIVE
- GPIOD_ACTIVE_LOW

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c
index 84e5013..757ab71 100644
--- a/drivers/gpio/gpio-uclass.c
+++ b/drivers/gpio/gpio-uclass.c
@@ -572,11 +572,16 @@
 		return ret;
 	}
 
-	if (flags & GPIOD_IS_OUT) {
-		ret = ops->direction_output(dev, desc->offset,
-					    GPIOD_FLAGS_OUTPUT(flags));
-	} else if (flags & GPIOD_IS_IN) {
-		ret = ops->direction_input(dev, desc->offset);
+	/* GPIOD_ are directly managed by driver in set_dir_flags*/
+	if (ops->set_dir_flags) {
+		ret = ops->set_dir_flags(dev, desc->offset, flags);
+	} else {
+		if (flags & GPIOD_IS_OUT) {
+			ret = ops->direction_output(dev, desc->offset,
+						    GPIOD_FLAGS_OUTPUT(flags));
+		} else if (flags & GPIOD_IS_IN) {
+			ret = ops->direction_input(dev, desc->offset);
+		}
 	}
 
 	return ret;
@@ -1146,6 +1151,8 @@
 			ops->get_function += gd->reloc_off;
 		if (ops->xlate)
 			ops->xlate += gd->reloc_off;
+		if (ops->set_dir_flags)
+			ops->set_dir_flags += gd->reloc_off;
 		if (ops->get_dir_flags)
 			ops->get_dir_flags += gd->reloc_off;
 
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 7c1f71b..859f41a 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -299,6 +299,22 @@
 		     struct ofnode_phandle_args *args);
 
 	/**
+	 * set_dir_flags() - Set GPIO dir flags
+	 *
+	 * This function should set up the GPIO configuration according to the
+	 * information provide by the direction flags bitfield.
+	 *
+	 * This method is optional.
+	 *
+	 * @dev:	GPIO device
+	 * @offset:	GPIO offset within that device
+	 * @flags:	GPIO configuration to use
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*set_dir_flags)(struct udevice *dev, unsigned int offset,
+			     ulong flags);
+
+	/**
 	 * get_dir_flags() - Get GPIO dir flags
 	 *
 	 * This function return the GPIO direction flags used.