[media] radio-si4713: use V4L2 core lock

Simplify locking by using the V4L2 core lock mechanism. This allows us to
remove all locking from the i2c module. This will also simplify the upcoming
conversion to the control framework.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Eduardo Valentin <edubezval@gmail.com>
Tested-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/radio/radio-si4713.c

@@ -49,6 +49,7 @@ MODULE_ALIAS("platform:radio-si4713");
 struct radio_si4713_device {
 	struct v4l2_device		v4l2_dev;
 	struct video_device		radio_dev;
+	struct mutex lock;
 };
 
 /* radio_si4713_fops - file operations interface */
@@ -247,6 +248,7 @@ static int radio_si4713_pdriver_probe(struct platform_device *pdev)
 		rval = -ENOMEM;
 		goto exit;
 	}
+	mutex_init(&rsdev->lock);
 
 	rval = v4l2_device_register(&pdev->dev, &rsdev->v4l2_dev);
 	if (rval) {
@@ -272,6 +274,8 @@ static int radio_si4713_pdriver_probe(struct platform_device *pdev)
 
 	rsdev->radio_dev = radio_si4713_vdev_template;
 	rsdev->radio_dev.v4l2_dev = &rsdev->v4l2_dev;
+	/* Serialize all access to the si4713 */
+	rsdev->radio_dev.lock = &rsdev->lock;
 	video_set_drvdata(&rsdev->radio_dev, rsdev);
 	if (video_register_device(&rsdev->radio_dev, VFL_TYPE_RADIO, radio_nr)) {
 		dev_err(&pdev->dev, "Could not register video device.\n");

drivers/media/radio/si4713-i2c.h

@@ -220,7 +220,6 @@ struct si4713_device {
 	/* v4l2_subdev and i2c reference (v4l2_subdev priv data) */
 	struct v4l2_subdev sd;
 	/* private data structures */
-	struct mutex mutex;
 	struct completion work;
 	struct rds_info rds_info;
 	struct limiter_info limiter_info;