[PATCH 1/7] gpiolib: gpiolib-of: Implement device tree gpio-names based lookup

[Chen-Yu Tsai <wens@csie.org>]

This patch provides of_get_gpiod_flags_by_name(), which looks up GPIO
phandles by name only, through gpios/gpio-names, and not by index.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
 drivers/gpio/gpiolib-of.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of_gpio.h   |  3 +++
 2 files changed, 51 insertions(+)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 2024d45..5c586fa 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -97,6 +97,54 @@ struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np,
 EXPORT_SYMBOL(of_get_named_gpiod_flags);
 
 /**
+ * of_get_gpiod_flags_by_name() - Get a GPIO descriptor and flags by name
+ * @np:		device node to get GPIO from
+ * @name:	matching name of gpio phandle
+ * @flags:	a flags pointer to fill in
+ *
+ * Returns GPIO descriptor to use with Linux GPIO API, or one of the errno
+ * value on the error condition. If @flags is not NULL the function also fills
+ * in flags for the GPIO.
+ */
+struct gpio_desc *of_get_gpiod_flags_by_name(struct device_node *np,
+		const char *name, enum of_gpio_flags *flags)
+{
+	/* Return -EPROBE_DEFER to support probe() functions to be called
+	 * later when the GPIO actually becomes available
+	 */
+	struct gg_data gg_data = {
+		.flags = flags,
+		.out_gpio = ERR_PTR(-EPROBE_DEFER)
+	};
+	int index = 0;
+	int ret;
+
+	/* exit if no name given */
+	if (!name)
+		return ERR_PTR(-EINVAL);
+
+	/* .of_xlate might decide to not fill in the flags, so clear it. */
+	if (flags)
+		*flags = 0;
+
+	if (name)
+		index = of_property_match_string(np, "gpio-names", name);
+
+	ret = of_parse_phandle_with_args(np, "gpios", "#gpio-cells", index,
+					 &gg_data.gpiospec);
+
+	if (ret)
+		return ERR_PTR(ret);
+
+	gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
+
+	of_node_put(gg_data.gpiospec.np);
+
+	return gg_data.out_gpio;
+}
+EXPORT_SYMBOL(of_get_gpiod_flags_by_names);
+
+/**
  * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
  * @gc:		pointer to the gpio_chip structure
  * @np:		device node of the GPIO chip
diff --git a/include/linux/of_gpio.h b/include/linux/of_gpio.h
index f14123a..134331f 100644
--- a/include/linux/of_gpio.h
+++ b/include/linux/of_gpio.h
@@ -51,6 +51,9 @@ static inline struct of_mm_gpio_chip *to_of_mm_gpio_chip(struct gpio_chip *gc)
 extern struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np,
 		const char *list_name, int index, enum of_gpio_flags *flags);
 
+extern struct gpio_desc *of_get_gpiod_flags_by_name(struct device_node *np,
+		const char *name, enum of_gpio_flags *flags);
+
 extern int of_mm_gpiochip_add(struct device_node *np,
 			      struct of_mm_gpio_chip *mm_gc);
 
-- 
1.9.1