[media] mt9p031: Add support for regulators

Enable the regulators when powering the sensor up, and disable them when
powering it down.
The regulators are mandatory. Boards that don't allow controlling the
sensor power lines must provide fixed voltage regulators.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/i2c/mt9p031.c

@@ -19,6 +19,7 @@
 #include <linux/i2c.h>
 #include <linux/log2.h>
 #include <linux/pm.h>
+#include <linux/regulator/consumer.h>
 #include <linux/slab.h>
 #include <linux/videodev2.h>
 
@@ -121,6 +122,10 @@ struct mt9p031 {
 	struct mutex power_lock; /* lock to protect power_count */
 	int power_count;
 
+	struct regulator *vaa;
+	struct regulator *vdd;
+	struct regulator *vdd_io;
+
 	enum mt9p031_model model;
 	struct aptina_pll pll;
 	int reset;
@@ -264,6 +269,11 @@ static int mt9p031_power_on(struct mt9p031 *mt9p031)
 		usleep_range(1000, 2000);
 	}
 
+	/* Bring up the supplies */
+	regulator_enable(mt9p031->vdd);
+	regulator_enable(mt9p031->vdd_io);
+	regulator_enable(mt9p031->vaa);
+
 	/* Emable clock */
 	if (mt9p031->pdata->set_xclk)
 		mt9p031->pdata->set_xclk(&mt9p031->subdev,
@@ -285,6 +295,10 @@ static void mt9p031_power_off(struct mt9p031 *mt9p031)
 		usleep_range(1000, 2000);
 	}
 
+	regulator_disable(mt9p031->vaa);
+	regulator_disable(mt9p031->vdd_io);
+	regulator_disable(mt9p031->vdd);
+
 	if (mt9p031->pdata->set_xclk)
 		mt9p031->pdata->set_xclk(&mt9p031->subdev, 0);
 }
@@ -937,6 +951,16 @@ static int mt9p031_probe(struct i2c_client *client,
 	mt9p031->model = did->driver_data;
 	mt9p031->reset = -1;
 
+	mt9p031->vaa = devm_regulator_get(&client->dev, "vaa");
+	mt9p031->vdd = devm_regulator_get(&client->dev, "vdd");
+	mt9p031->vdd_io = devm_regulator_get(&client->dev, "vdd_io");
+
+	if (IS_ERR(mt9p031->vaa) || IS_ERR(mt9p031->vdd) ||
+	    IS_ERR(mt9p031->vdd_io)) {
+		dev_err(&client->dev, "Unable to get regulators\n");
+		return -ENODEV;
+	}
+
 	v4l2_ctrl_handler_init(&mt9p031->ctrls, ARRAY_SIZE(mt9p031_ctrls) + 6);
 
 	v4l2_ctrl_new_std(&mt9p031->ctrls, &mt9p031_ctrl_ops,