[media] em28xx: PCTV tripleStick (292e) LNA support

External LNA between antenna connector and RF tuner is controlled
by EM28178 GPIO 0. GPIO value 1 is LNA active and value 0 is LNA
disabled.

Signed-off-by: Antti Palosaari <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/usb/em28xx/em28xx-dvb.c

···
 #endif
 }
 
+static int em28xx_pctv_292e_set_lna(struct dvb_frontend *fe)
+{
+	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
+	struct em28xx_i2c_bus *i2c_bus = fe->dvb->priv;
+	struct em28xx *dev = i2c_bus->dev;
+	u8 lna;
+
+	if (c->lna == 1)
+		lna = 0x01;
+	else
+		lna = 0x00;
+
+	return em28xx_write_reg_bits(dev, EM2874_R80_GPIO_P0_CTRL, lna, 0x01);
+}
+
 static int em28xx_mt352_terratec_xs_init(struct dvb_frontend *fe)
 {
 	/* Values extracted from a USB trace of the Terratec Windows driver */
···
 			}
 
 			dvb->i2c_client_tuner = client;
+			dvb->fe[0]->ops.set_lna = em28xx_pctv_292e_set_lna;
 		}
 		break;
 	default: