media: ad5820: Add support for enable pin

This patch adds support for a programmable enable pin. It can be used in
situations where the ANA-vcc is not configurable (dummy-regulator), or
just to have a more fine control of the power saving.

The use of the enable pin is optional.
Signed-off-by: Ricardo Ribalda Delgado <ribalda@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/i2c/Kconfig

@@ -975,7 +975,7 @@ if MEDIA_CAMERA_SUPPORT
 
 config VIDEO_AD5820
 	tristate "AD5820 lens voice coil support"
-	depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER
+	depends on GPIOLIB && I2C && VIDEO_V4L2 && MEDIA_CONTROLLER
 	help
 	  This is a driver for the AD5820 camera lens voice coil.
 	  It is used for example in Nokia N900 (RX-51).

drivers/media/i2c/ad5820.c

@@ -19,6 +19,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/regulator/consumer.h>
+#include <linux/gpio/consumer.h>
 
 #include <media/v4l2-ctrls.h>
 #include <media/v4l2-device.h>
@@ -47,6 +48,8 @@ struct ad5820_device {
 	u32 focus_ramp_time;
 	u32 focus_ramp_mode;
 
+	struct gpio_desc *enable_gpio;
+
 	struct mutex power_lock;
 	int power_count;
 
@@ -114,6 +117,8 @@ static int ad5820_power_off(struct ad5820_device *coil, bool standby)
 		ret = ad5820_update_hw(coil);
 	}
 
+	gpiod_set_value_cansleep(coil->enable_gpio, 0);
+
 	ret2 = regulator_disable(coil->vana);
 	if (ret)
 		return ret;
@@ -128,6 +133,8 @@ static int ad5820_power_on(struct ad5820_device *coil, bool restore)
 	if (ret < 0)
 		return ret;
 
+	gpiod_set_value_cansleep(coil->enable_gpio, 1);
+
 	if (restore) {
 		/* Restore the hardware settings. */
 		coil->standby = false;
@@ -138,6 +145,7 @@ static int ad5820_power_on(struct ad5820_device *coil, bool restore)
 	return 0;
 
 fail:
+	gpiod_set_value_cansleep(coil->enable_gpio, 0);
 	coil->standby = true;
 	regulator_disable(coil->vana);
 
@@ -304,6 +312,15 @@ static int ad5820_probe(struct i2c_client *client,
 		return ret;
 	}
 
+	coil->enable_gpio = devm_gpiod_get_optional(&client->dev, "enable",
+						    GPIOD_OUT_LOW);
+	if (IS_ERR(coil->enable_gpio)) {
+		ret = PTR_ERR(coil->enable_gpio);
+		if (ret != -EPROBE_DEFER)
+			dev_err(&client->dev, "could not get enable gpio\n");
+		return ret;
+	}
+
 	mutex_init(&coil->power_lock);
 
 	v4l2_i2c_subdev_init(&coil->subdev, client, &ad5820_ops);