[U-Boot] [PATCH v2 08/18] gpio: Add gpio_request_simple function

[Mario Six]

For board initialization, usage of GPIOs is sometimes needed, e.g. to
initialize certain devices such as FPGAs. But since there currently is no
device associated to the board itself, initialization routines have to
cumbersomely get GPIOs via gpio_request_by_name_nodev.

This patch adds a convenience function aimed at such scenarios, which wraps the
gpio_request_by_name_nodev and some error checking. The GPIO is identified via
its compatible string in the device tree.

Signed-off-by: Mario Six <mario.six at gdsys.cc>
---
Changes in v2:

New in v2
---
 drivers/gpio/gpio-uclass.c | 17 +++++++++++++++++
 include/asm-generic/gpio.h | 22 ++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c
index 4559739..197d987 100644
--- a/drivers/gpio/gpio-uclass.c
+++ b/drivers/gpio/gpio-uclass.c
@@ -751,6 +751,23 @@ int gpio_request_list_by_name(struct udevice *dev, const char *list_name,
 					       flags);
 }

+bool gpio_request_simple(char *name, struct gpio_desc *gpio)
+{
+	int node = fdt_node_offset_by_compatible(gd->fdt_blob, 0, name);
+	int ret;
+
+	if (node < 0)
+		return false;
+
+	ret = gpio_request_by_name_nodev(gd->fdt_blob, node, "gpios", 0, gpio,
+					 0);
+
+	if (ret < 0)
+		return false;
+
+	return dm_gpio_is_valid(gpio);
+}
+
 int gpio_get_list_count(struct udevice *dev, const char *list_name)
 {
 	int ret;
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 4aa0004..5c3e599 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -457,6 +457,28 @@ int gpio_request_list_by_name(struct udevice *dev, const char *list_name,
 			      int flags);

 /**
+ * gpio_request_simple() - Simple wrapper function to request GPIO via
+ *                         fdt compatible name
+ *
+ * Convenience method to get useable GPIO description information from a device
+ * tree declaration such as:
+ *
+ *   fpga_ready_gpio {
+ *       compatible = "generic,fpga-ready-gpio";
+ *       gpios = <&PCA22 27 0>;
+ *   };
+ *
+ * This is convenient for setting and reading GPIOs from board files (where no
+ * associated device is in play).
+ *
+ * @name: The fdt compatible string of the GPIO in question
+ * @gpio: Return the GPIO description information of the GPIO in question
+ *
+ * @return true if the operation succeeded, false if not
+ */
+bool gpio_request_simple(char *name, struct gpio_desc *gpio);
+
+/**
  * dm_gpio_request() - manually request a GPIO
  *
  * Note: This function should only be used for testing / debugging. Instead.
--
2.9.0