media: dvb-frontends/stv0367: SNR DVBv5 statistics for DVB-C and T

Add signal-to-noise-ratio as provided by the demodulator in decibel scale.
QAM/DVB-C needs some intlog calculation to have usable dB values, OFDM/
DVB-T values from the demod look alright already and are provided as-is.

Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/media/dvb-frontends/stv0367.c b/drivers/media/dvb-frontends/stv0367.c
index f266c18..fee2a15 100644 (file)
--- a/drivers/media/dvb-frontends/stv0367.c
+++ b/drivers/media/dvb-frontends/stv0367.c
@@ -25,6 +25,8 @@
 #include <linux/slab.h>
 #include <linux/i2c.h>
 
+#include "dvb_math.h"
+
 #include "stv0367.h"
 #include "stv0367_defs.h"
 #include "stv0367_regs.h"
@@ -2996,6 +2998,37 @@ static int stv0367ddb_set_frontend(struct dvb_frontend *fe)
        return -EINVAL;
 }
 
+static void stv0367ddb_read_snr(struct dvb_frontend *fe)
+{
+       struct stv0367_state *state = fe->demodulator_priv;
+       struct dtv_frontend_properties *p = &fe->dtv_property_cache;
+       int cab_pwr;
+       u32 regval, tmpval, snrval = 0;
+
+       switch (state->activedemod) {
+       case demod_ter:
+               snrval = stv0367ter_snr_readreg(fe);
+               break;
+       case demod_cab:
+               cab_pwr = stv0367cab_snr_power(fe);
+               regval = stv0367cab_snr_readreg(fe, 0);
+
+               /* prevent division by zero */
+               if (!regval)
+                       snrval = 0;
+
+               tmpval = (cab_pwr * 320) / regval;
+               snrval = ((tmpval != 0) ? (intlog2(tmpval) / 5581) : 0);
+               break;
+       default:
+               p->cnr.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
+               return;
+       }
+
+       p->cnr.stat[0].scale = FE_SCALE_DECIBEL;
+       p->cnr.stat[0].uvalue = snrval;
+}
+
 static void stv0367ddb_read_ucblocks(struct dvb_frontend *fe)
 {
        struct stv0367_state *state = fe->demodulator_priv;
@@ -3040,6 +3073,12 @@ static int stv0367ddb_read_status(struct dvb_frontend *fe,
        if (ret)
                return ret;
 
+       /* read carrier/noise when a carrier is detected */
+       if (*status & FE_HAS_CARRIER)
+               stv0367ddb_read_snr(fe);
+       else
+               p->cnr.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
+
        /* stop if demod isn't locked */
        if (!(*status & FE_HAS_LOCK)) {
                p->block_error.stat[0].scale = FE_SCALE_NOT_AVAILABLE;