[media] rtl2830: implement .read_signal_strength()

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/dvb/frontends/rtl2830.c b/drivers/media/dvb/frontends/rtl2830.c
index 2660986..6e4029d 100644 (file)
--- a/drivers/media/dvb/frontends/rtl2830.c
+++ b/drivers/media/dvb/frontends/rtl2830.c
@@ -474,8 +474,29 @@ static int rtl2830_read_ucblocks(struct dvb_frontend *fe, u32 *ucblocks)
 
 static int rtl2830_read_signal_strength(struct dvb_frontend *fe, u16 *strength)
 {
-       *strength = 0;
+       struct rtl2830_priv *priv = fe->demodulator_priv;
+       int ret;
+       u8 buf[2];
+       u16 if_agc_raw, if_agc;
+
+       ret = rtl2830_rd_regs(priv, 0x359, buf, 2);
+       if (ret)
+               goto err;
+
+       if_agc_raw = (buf[0] << 8 | buf[1]) & 0x3fff;
+
+       if (if_agc_raw & (1 << 9))
+               if_agc = -(~(if_agc_raw - 1) & 0x1ff);
+       else
+               if_agc = if_agc_raw;
+
+       *strength = (u8) (55 - if_agc / 182);
+       *strength |= *strength << 8;
+
        return 0;
+err:
+       dbg("%s: failed=%d", __func__, ret);
+       return ret;
 }
 
 static struct dvb_frontend_ops rtl2830_ops;