of/gpio: export of_gpio_simple_xlate

Allow GPIO drivers to use of_gpio_simple_xlate. This is useful for the
generic GPIO driver for example where gpio_chip is embedded in
bgpio_chip and doesn't need of_mm_gpio_chip but has a simple 1:1 GPIO
mapping.

Cc: Anton Vorontsov <[e-mail]>
Cc: Grant Likely <[e-mail]>
Signed-off-by: Jamie Iles <[e-mail]>
Signed-off-by: Grant Likely <[e-mail]>

drivers/of/gpio.c

···
  * gpio chips. This function performs only one sanity check: whether gpio
  * is less than ngpios (that is specified in the gpio_chip).
  */
-static int of_gpio_simple_xlate(struct gpio_chip *gc, struct device_node *np,
-				const void *gpio_spec, u32 *flags)
+int of_gpio_simple_xlate(struct gpio_chip *gc, struct device_node *np,
+			 const void *gpio_spec, u32 *flags)
 {
 	const __be32 *gpio = gpio_spec;
 	const u32 n = be32_to_cpup(gpio);
···
 
 	return n;
 }
+EXPORT_SYMBOL(of_gpio_simple_xlate);
 
 /**
  * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)

include/linux/of_gpio.h

···
 extern void of_gpiochip_add(struct gpio_chip *gc);
 extern void of_gpiochip_remove(struct gpio_chip *gc);
 extern struct gpio_chip *of_node_to_gpiochip(struct device_node *np);
+extern int of_gpio_simple_xlate(struct gpio_chip *gc, struct device_node *np,
+				const void *gpio_spec, u32 *flags);
 
 #else /* CONFIG_OF_GPIO */
 
···
 static inline unsigned int of_gpio_count(struct device_node *np)
 {
 	return 0;
+}
+
+static inline int of_gpio_simple_xlate(struct gpio_chip *gc,
+				       struct device_node *np,
+				       const void *gpio_spec, u32 *flags)
+{
+	return -ENOSYS;
 }
 
 static inline void of_gpiochip_add(struct gpio_chip *gc) { }