gpiolib: provide generic request/free implementations

Provide generic request/free implementations that pinctrl aware gpio
drivers can use instead of open coding if they use a 1:1 pin to gpio
signal mapping.
Signed-off-by: Jonas Gorski <jogo@openwrt.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -15,6 +15,7 @@
 #include <linux/acpi.h>
 #include <linux/gpio/driver.h>
 #include <linux/gpio/machine.h>
+#include <linux/pinctrl/consumer.h>
 
 #include "gpiolib.h"
 
@@ -745,6 +746,28 @@ static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip) {}
 
 #endif /* CONFIG_GPIOLIB_IRQCHIP */
 
+/**
+ * gpiochip_generic_request() - request the gpio function for a pin
+ * @chip: the gpiochip owning the GPIO
+ * @offset: the offset of the GPIO to request for GPIO function
+ */
+int gpiochip_generic_request(struct gpio_chip *chip, unsigned offset)
+{
+	return pinctrl_request_gpio(chip->base + offset);
+}
+EXPORT_SYMBOL_GPL(gpiochip_generic_request);
+
+/**
+ * gpiochip_generic_free() - free the gpio function from a pin
+ * @chip: the gpiochip to request the gpio function for
+ * @offset: the offset of the GPIO to free from GPIO function
+ */
+void gpiochip_generic_free(struct gpio_chip *chip, unsigned offset)
+{
+	pinctrl_free_gpio(chip->base + offset);
+}
+EXPORT_SYMBOL_GPL(gpiochip_generic_free);
+
 #ifdef CONFIG_PINCTRL
 
 /**

include/linux/gpio/driver.h

@@ -206,6 +206,9 @@ int _gpiochip_irqchip_add(struct gpio_chip *gpiochip,
 
 #endif /* CONFIG_GPIOLIB_IRQCHIP */
 
+int gpiochip_generic_request(struct gpio_chip *chip, unsigned offset);
+void gpiochip_generic_free(struct gpio_chip *chip, unsigned offset);
+
 #ifdef CONFIG_PINCTRL
 
 /**