media: af9013: dvbv5 signal strength

Implement dvbv5 signal strength estimate. We know tuner dependent
-80dBm and -50dBm agc values, construct line equation and use it to
map agc value to signal strength estimate.

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

diff --git a/drivers/media/dvb-frontends/af9013.c b/drivers/media/dvb-frontends/af9013.c
index 30cf837058da8a3026f64bb7b7b55a760ab16f0b..4cb6371572c52ed09879f7c9c90ab21ed7f067ad 100644 (file)
--- a/drivers/media/dvb-frontends/af9013.c
+++ b/drivers/media/dvb-frontends/af9013.c
@@ -41,8 +41,11 @@ struct af9013_state {
        u16 snr;
        u32 bandwidth_hz;
        enum fe_status fe_status;
+       /* RF and IF AGC limits used for signal strength calc */
+       u8 strength_en, rf_agc_50, rf_agc_80, if_agc_50, if_agc_80;
        unsigned long set_frontend_jiffies;
        unsigned long read_status_jiffies;
+       unsigned long strength_jiffies;
        bool first_tune;
        bool i2c_gate_state;
        unsigned int statistics_step:3;
@@ -751,8 +754,12 @@ static int af9013_read_status(struct dvb_frontend *fe, enum fe_status *status)
 {
        struct af9013_state *state = fe->demodulator_priv;
        struct i2c_client *client = state->client;
-       int ret;
-       unsigned int utmp, utmp1;
+       struct dtv_frontend_properties *c = &fe->dtv_property_cache;
+       int ret, stmp1;
+       unsigned int utmp, utmp1, utmp2, utmp3, utmp4;
+       u8 buf[2];
+
+       dev_dbg(&client->dev, "\n");
 
        /*
         * Return status from the cache if it is younger than 2000ms with the
@@ -791,6 +798,77 @@ static int af9013_read_status(struct dvb_frontend *fe, enum fe_status *status)
                *status = utmp1;
        }
 
+       /* Signal strength */
+       switch (state->strength_en) {
+       case 0:
+               /* Check if we support signal strength */
+               ret = regmap_read(state->regmap, 0x9bee, &utmp);
+               if (ret)
+                       goto err;
+
+               if ((utmp >> 0) & 0x01) {
+                       /* Read agc values for signal strength estimation */
+                       ret = regmap_read(state->regmap, 0x9bbd, &utmp1);
+                       if (ret)
+                               goto err;
+                       ret = regmap_read(state->regmap, 0x9bd0, &utmp2);
+                       if (ret)
+                               goto err;
+                       ret = regmap_read(state->regmap, 0x9be2, &utmp3);
+                       if (ret)
+                               goto err;
+                       ret = regmap_read(state->regmap, 0x9be4, &utmp4);
+                       if (ret)
+                               goto err;
+
+                       state->rf_agc_50 = utmp1;
+                       state->rf_agc_80 = utmp2;
+                       state->if_agc_50 = utmp3;
+                       state->if_agc_80 = utmp4;
+                       dev_dbg(&client->dev,
+                               "rf_agc_50 %u, rf_agc_80 %u, if_agc_50 %u, if_agc_80 %u\n",
+                               utmp1, utmp2, utmp3, utmp4);
+
+                       state->strength_en = 1;
+               } else {
+                       /* Signal strength is not supported */
+                       state->strength_en = 2;
+                       break;
+               }
+               /* Fall through */
+       case 1:
+               if (time_is_after_jiffies(state->strength_jiffies + msecs_to_jiffies(2000)))
+                       break;
+
+               /* Read value */
+               ret = regmap_bulk_read(state->regmap, 0xd07c, buf, 2);
+               if (ret)
+                       goto err;
+
+               /*
+                * Construct line equation from tuner dependent -80/-50 dBm agc
+                * limits and use it to map current agc value to dBm estimate
+                */
+               #define agc_gain (buf[0] + buf[1])
+               #define agc_gain_50dbm (state->rf_agc_50 + state->if_agc_50)
+               #define agc_gain_80dbm (state->rf_agc_80 + state->if_agc_80)
+               stmp1 = 30000 * (agc_gain - agc_gain_80dbm) /
+                       (agc_gain_50dbm - agc_gain_80dbm) - 80000;
+
+               dev_dbg(&client->dev,
+                       "strength %d, agc_gain %d, agc_gain_50dbm %d, agc_gain_80dbm %d\n",
+                       stmp1, agc_gain, agc_gain_50dbm, agc_gain_80dbm);
+
+               state->strength_jiffies = jiffies;
+
+               c->strength.stat[0].scale = FE_SCALE_DECIBEL;
+               c->strength.stat[0].svalue = stmp1;
+               break;
+       default:
+               c->strength.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
+               break;
+       }
+
        return 0;
 err:
        dev_dbg(&client->dev, "failed %d\n", ret);
@@ -1512,6 +1590,7 @@ static int af9013_probe(struct i2c_client *client,
 
        /* Init stats to indicate which stats are supported */
        c = &state->fe.dtv_property_cache;
+       c->strength.len = 1;
        c->cnr.len = 1;
 
        dev_info(&client->dev, "Afatech AF9013 successfully attached\n");