[media] af9033: implement .read_snr()

Returns values as 0.1 dB resolution as preferred nowadays.
Actual resolution is 1 dB.

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

drivers/media/dvb/frontends/af9033.c

@@ -540,9 +540,56 @@ err:
 
 static int af9033_read_snr(struct dvb_frontend *fe, u16 *snr)
 {
-	*snr = 0;
+	struct af9033_state *state = fe->demodulator_priv;
+	int ret, i, len;
+	u8 buf[3], tmp;
+	u32 snr_val;
+	const struct val_snr *uninitialized_var(snr_lut);
+
+	/* read value */
+	ret = af9033_rd_regs(state, 0x80002c, buf, 3);
+	if (ret < 0)
+		goto err;
+
+	snr_val = (buf[2] << 16) | (buf[1] << 8) | buf[0];
+
+	/* read current modulation */
+	ret = af9033_rd_reg(state, 0x80f903, &tmp);
+	if (ret < 0)
+		goto err;
+
+	switch ((tmp >> 0) & 3) {
+	case 0:
+		len = ARRAY_SIZE(qpsk_snr_lut);
+		snr_lut = qpsk_snr_lut;
+		break;
+	case 1:
+		len = ARRAY_SIZE(qam16_snr_lut);
+		snr_lut = qam16_snr_lut;
+		break;
+	case 2:
+		len = ARRAY_SIZE(qam64_snr_lut);
+		snr_lut = qam64_snr_lut;
+		break;
+	default:
+		goto err;
+	}
+
+	for (i = 0; i < len; i++) {
+		tmp = snr_lut[i].snr;
+
+		if (snr_val < snr_lut[i].val)
+			break;
+	}
+
+	*snr = tmp * 10; /* dB/10 */
 
 	return 0;
+
+err:
+	pr_debug("%s: failed=%d\n", __func__, ret);
+
+	return ret;
 }
 
 static int af9033_read_signal_strength(struct dvb_frontend *fe, u16 *strength)

drivers/media/dvb/frontends/af9033_priv.h

@@ -47,6 +47,11 @@ struct clock_adc {
 	u32 adc;
 };
 
+struct val_snr {
+	u32 val;
+	u8 snr;
+};
+
 /* Xtal clock vs. ADC clock lookup table */
 static const struct clock_adc clock_adc_lut[] = {
 	{ 16384000, 20480000 },
@@ -85,6 +90,99 @@ static const struct coeff coeff_lut[] = {
 	},
 };
 
+/* QPSK SNR lookup table */
+static const struct val_snr qpsk_snr_lut[] = {
+	{ 0x0b4771,  0 },
+	{ 0x0c1aed,  1 },
+	{ 0x0d0d27,  2 },
+	{ 0x0e4d19,  3 },
+	{ 0x0e5da8,  4 },
+	{ 0x107097,  5 },
+	{ 0x116975,  6 },
+	{ 0x1252d9,  7 },
+	{ 0x131fa4,  8 },
+	{ 0x13d5e1,  9 },
+	{ 0x148e53, 10 },
+	{ 0x15358b, 11 },
+	{ 0x15dd29, 12 },
+	{ 0x168112, 13 },
+	{ 0x170b61, 14 },
+	{ 0x17a532, 15 },
+	{ 0x180f94, 16 },
+	{ 0x186ed2, 17 },
+	{ 0x18b271, 18 },
+	{ 0x18e118, 19 },
+	{ 0x18ff4b, 20 },
+	{ 0x190af1, 21 },
+	{ 0x191451, 22 },
+	{ 0xffffff, 23 },
+};
+
+/* QAM16 SNR lookup table */
+static const struct val_snr qam16_snr_lut[] = {
+	{ 0x04f0d5,  0 },
+	{ 0x05387a,  1 },
+	{ 0x0573a4,  2 },
+	{ 0x05a99e,  3 },
+	{ 0x05cc80,  4 },
+	{ 0x05eb62,  5 },
+	{ 0x05fecf,  6 },
+	{ 0x060b80,  7 },
+	{ 0x062501,  8 },
+	{ 0x064865,  9 },
+	{ 0x069604, 10 },
+	{ 0x06f356, 11 },
+	{ 0x07706a, 12 },
+	{ 0x0804d3, 13 },
+	{ 0x089d1a, 14 },
+	{ 0x093e3d, 15 },
+	{ 0x09e35d, 16 },
+	{ 0x0a7c3c, 17 },
+	{ 0x0afaf8, 18 },
+	{ 0x0b719d, 19 },
+	{ 0x0bda6a, 20 },
+	{ 0x0c0c75, 21 },
+	{ 0x0c3f7d, 22 },
+	{ 0x0c5e62, 23 },
+	{ 0x0c6c31, 24 },
+	{ 0x0c7925, 25 },
+	{ 0xffffff, 26 },
+};
+
+/* QAM64 SNR lookup table */
+static const struct val_snr qam64_snr_lut[] = {
+	{ 0x0256d0,  0 },
+	{ 0x027a65,  1 },
+	{ 0x029873,  2 },
+	{ 0x02b7fe,  3 },
+	{ 0x02cf1e,  4 },
+	{ 0x02e234,  5 },
+	{ 0x02f409,  6 },
+	{ 0x030046,  7 },
+	{ 0x030844,  8 },
+	{ 0x030a02,  9 },
+	{ 0x030cde, 10 },
+	{ 0x031031, 11 },
+	{ 0x03144c, 12 },
+	{ 0x0315dd, 13 },
+	{ 0x031920, 14 },
+	{ 0x0322d0, 15 },
+	{ 0x0339fc, 16 },
+	{ 0x0364a1, 17 },
+	{ 0x038bcc, 18 },
+	{ 0x03c7d3, 19 },
+	{ 0x0408cc, 20 },
+	{ 0x043bed, 21 },
+	{ 0x048061, 22 },
+	{ 0x04be95, 23 },
+	{ 0x04fa7d, 24 },
+	{ 0x052405, 25 },
+	{ 0x05570d, 26 },
+	{ 0x059feb, 27 },
+	{ 0x05bf38, 28 },
+	{ 0xffffff, 29 },
+};
+
 static const struct reg_val ofsm_init[] = {
 	{ 0x800051, 0x01 },
 	{ 0x800070, 0x0a },