[media] hackrf: add control for RF amplifier

There is Avago MGA-81563 amplifier just right after antenna connector.
It could be turned on/off and its gain is around 12dB.
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/usb/hackrf/hackrf.c

@@ -32,6 +32,7 @@ enum {
 	CMD_BOARD_ID_READ                  = 0x0e,
 	CMD_VERSION_STRING_READ            = 0x0f,
 	CMD_SET_FREQ                       = 0x10,
+	CMD_AMP_ENABLE                     = 0x11,
 	CMD_SET_LNA_GAIN                   = 0x13,
 	CMD_SET_VGA_GAIN                   = 0x14,
 };
@@ -135,6 +136,7 @@ struct hackrf_dev {
 	struct v4l2_ctrl_handler hdl;
 	struct v4l2_ctrl *bandwidth_auto;
 	struct v4l2_ctrl *bandwidth;
+	struct v4l2_ctrl *rf_gain;
 	struct v4l2_ctrl *lna_gain;
 	struct v4l2_ctrl *if_gain;
 
@@ -166,6 +168,7 @@ static int hackrf_ctrl_msg(struct hackrf_dev *dev, u8 request, u16 value,
 	switch (request) {
 	case CMD_SET_TRANSCEIVER_MODE:
 	case CMD_SET_FREQ:
+	case CMD_AMP_ENABLE:
 	case CMD_SAMPLE_RATE_SET:
 	case CMD_BASEBAND_FILTER_BANDWIDTH_SET:
 		pipe = usb_sndctrlpipe(dev->udev, 0);
@@ -953,6 +956,22 @@ static int hackrf_set_bandwidth(struct hackrf_dev *dev)
 	return ret;
 }
 
+static int hackrf_set_rf_gain(struct hackrf_dev *dev)
+{
+	int ret;
+	u8 u8tmp;
+
+	dev_dbg(dev->dev, "rf val=%d->%d\n",
+		dev->rf_gain->cur.val, dev->rf_gain->val);
+
+	u8tmp = (dev->rf_gain->val) ? 1 : 0;
+	ret = hackrf_ctrl_msg(dev, CMD_AMP_ENABLE, u8tmp, 0, NULL, 0);
+	if (ret)
+		dev_dbg(dev->dev, "failed=%d\n", ret);
+
+	return ret;
+}
+
 static int hackrf_set_lna_gain(struct hackrf_dev *dev)
 {
 	int ret;
@@ -996,6 +1015,9 @@ static int hackrf_s_ctrl(struct v4l2_ctrl *ctrl)
 	case V4L2_CID_RF_TUNER_BANDWIDTH:
 		ret = hackrf_set_bandwidth(dev);
 		break;
+	case  V4L2_CID_RF_TUNER_RF_GAIN:
+		ret = hackrf_set_rf_gain(dev);
+		break;
 	case  V4L2_CID_RF_TUNER_LNA_GAIN:
 		ret = hackrf_set_lna_gain(dev);
 		break;
@@ -1081,13 +1103,15 @@ static int hackrf_probe(struct usb_interface *intf,
 	}
 
 	/* Register controls */
-	v4l2_ctrl_handler_init(&dev->hdl, 4);
+	v4l2_ctrl_handler_init(&dev->hdl, 5);
 	dev->bandwidth_auto = v4l2_ctrl_new_std(&dev->hdl, &hackrf_ctrl_ops,
 			V4L2_CID_RF_TUNER_BANDWIDTH_AUTO, 0, 1, 1, 1);
 	dev->bandwidth = v4l2_ctrl_new_std(&dev->hdl, &hackrf_ctrl_ops,
 			V4L2_CID_RF_TUNER_BANDWIDTH,
 			1750000, 28000000, 50000, 1750000);
 	v4l2_ctrl_auto_cluster(2, &dev->bandwidth_auto, 0, false);
+	dev->rf_gain = v4l2_ctrl_new_std(&dev->hdl, &hackrf_ctrl_ops,
+			V4L2_CID_RF_TUNER_RF_GAIN, 0, 12, 12, 0);
 	dev->lna_gain = v4l2_ctrl_new_std(&dev->hdl, &hackrf_ctrl_ops,
 			V4L2_CID_RF_TUNER_LNA_GAIN, 0, 40, 8, 0);
 	dev->if_gain = v4l2_ctrl_new_std(&dev->hdl, &hackrf_ctrl_ops,