gpiolib: acpi: Introduce acpi_get_and_request_gpiod() helper

We need to be able to translate GPIO resources in an ACPI device's _CRS
into GPIO descriptor array. Those are represented in _CRS as a pathname
to a GPIO device plus the pin's index number: the acpi_get_gpiod()
function is perfect for that purpose.

As it's currently only used internally within the GPIO layer, provide and
export a wrapper function that additionally holds a reference to the GPIO
device.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Daniel Scally <djrscally@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/gpio/gpiolib-acpi.c

@@ -128,6 +128,34 @@ static struct gpio_desc *acpi_get_gpiod(char *path, int pin)
 	return gpiochip_get_desc(chip, pin);
 }
 
+/**
+ * acpi_get_and_request_gpiod - Translate ACPI GPIO pin to GPIO descriptor and
+ *                              hold a refcount to the GPIO device.
+ * @path:      ACPI GPIO controller full path name, (e.g. "\\_SB.GPO1")
+ * @pin:       ACPI GPIO pin number (0-based, controller-relative)
+ * @label:     Label to pass to gpiod_request()
+ *
+ * This function is a simple pass-through to acpi_get_gpiod(), except that
+ * as it is intended for use outside of the GPIO layer (in a similar fashion to
+ * gpiod_get_index() for example) it also holds a reference to the GPIO device.
+ */
+struct gpio_desc *acpi_get_and_request_gpiod(char *path, int pin, char *label)
+{
+	struct gpio_desc *gpio;
+	int ret;
+
+	gpio = acpi_get_gpiod(path, pin);
+	if (IS_ERR(gpio))
+		return gpio;
+
+	ret = gpiod_request(gpio, label);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return gpio;
+}
+EXPORT_SYMBOL_GPL(acpi_get_and_request_gpiod);
+
 static irqreturn_t acpi_gpio_irq_handler(int irq, void *data)
 {
 	struct acpi_gpio_event *event = data;

include/linux/gpio/consumer.h

@@ -692,6 +692,8 @@ int devm_acpi_dev_add_driver_gpios(struct device *dev,
 				   const struct acpi_gpio_mapping *gpios);
 void devm_acpi_dev_remove_driver_gpios(struct device *dev);
 
+struct gpio_desc *acpi_get_and_request_gpiod(char *path, int pin, char *label);
+
 #else  /* CONFIG_GPIOLIB && CONFIG_ACPI */
 
 struct acpi_device;