of/gpio: Implement of_gpio_count()

This function is used to count how many GPIOs are specified for
a device node.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

drivers/of/gpio.c

@@ -79,6 +79,40 @@ int of_get_gpio_flags(struct device_node *np, int index,
 }
 EXPORT_SYMBOL(of_get_gpio_flags);
 
+/**
+ * of_gpio_count - Count GPIOs for a device
+ * @np:		device node to count GPIOs for
+ *
+ * The function returns the count of GPIOs specified for a node.
+ *
+ * Note that the empty GPIO specifiers counts too. For example,
+ *
+ * gpios = <0
+ *          &pio1 1 2
+ *          0
+ *          &pio2 3 4>;
+ *
+ * defines four GPIOs (so this function will return 4), two of which
+ * are not specified.
+ */
+unsigned int of_gpio_count(struct device_node *np)
+{
+	unsigned int cnt = 0;
+
+	do {
+		int ret;
+
+		ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells",
+						  cnt, NULL, NULL);
+		/* A hole in the gpios = <> counts anyway. */
+		if (ret < 0 && ret != -EEXIST)
+			break;
+	} while (++cnt);
+
+	return cnt;
+}
+EXPORT_SYMBOL(of_gpio_count);
+
 /**
  * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
  * @of_gc:	pointer to the of_gpio_chip structure

include/linux/of_gpio.h

@@ -65,6 +65,7 @@ static inline struct of_mm_gpio_chip *to_of_mm_gpio_chip(struct gpio_chip *gc)
 
 extern int of_get_gpio_flags(struct device_node *np, int index,
 			     enum of_gpio_flags *flags);
+extern unsigned int of_gpio_count(struct device_node *np);
 
 extern int of_mm_gpiochip_add(struct device_node *np,
 			      struct of_mm_gpio_chip *mm_gc);
@@ -81,6 +82,11 @@ static inline int of_get_gpio_flags(struct device_node *np, int index,
 	return -ENOSYS;
 }
 
+static inline unsigned int of_gpio_count(struct device_node *np)
+{
+	return 0;
+}
+
 #endif /* CONFIG_OF_GPIO */
 
 /**