V4L/DVB (11394): cx88: Add support for stereo and sap detection for A2

The patch implements reliable stereo and sap detection for the A2 sound
standard.  This is achieved by processing the samples of the audio RDS fifo of
the cx2388x chip. A2M, EIAJ and BTSC stereo/sap detection is also possible with
this new approach, but it's not implemented yet. Stereo detection when alsa
handles the sound also does not work yet.

Signed-off-by: Marton Balint <cus@fazekas.hu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 299 insertions, 0 deletions

diff --git a/drivers/media/video/cx88/cx88-dsp.c b/drivers/media/video/cx88/cx88-dsp.c
new file mode 100644
index 000000000000..a78286e853c3
--- /dev/null
+++ b/drivers/media/video/cx88/cx88-dsp.c
@@ -0,0 +1,299 @@
+/*
+ *
+ *  Stereo and SAP detection for cx88
+ *
+ *  Copyright (c) 2009 Marton Balint <cus@fazekas.hu>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/jiffies.h>
+
+#include "cx88.h"
+#include "cx88-reg.h"
+
+#define INT_PI			((s32)(3.141592653589 * 32768.0))
+
+#define compat_remainder(a, b) \
+	 ((float)(((s32)((a)*100))%((s32)((b)*100)))/100.0)
+
+#define baseband_freq(carrier, srate, tone) ((s32)( \
+	 (compat_remainder(carrier + tone, srate)) / srate * 2 * INT_PI))
+
+/* We calculate the baseband frequencies of the carrier and the pilot tones
+ * based on the the sampling rate of the audio rds fifo. */
+
+#define FREQ_A2_CARRIER         baseband_freq(54687.5, 2689.36, 0.0)
+#define FREQ_A2_DUAL            baseband_freq(54687.5, 2689.36, 274.1)
+#define FREQ_A2_STEREO          baseband_freq(54687.5, 2689.36, 117.5)
+
+/* The frequencies below are from the reference driver. They probably need
+ * further adjustments, because they are not tested at all. You may even need
+ * to play a bit with the registers of the chip to select the proper signal
+ * for the input of the audio rds fifo, and measure it's sampling rate to
+ * calculate the proper baseband frequencies... */
+
+#define FREQ_A2M_CARRIER	((s32)(2.114516 * 32768.0))
+#define FREQ_A2M_DUAL		((s32)(2.754916 * 32768.0))
+#define FREQ_A2M_STEREO		((s32)(2.462326 * 32768.0))
+
+#define FREQ_EIAJ_CARRIER	((s32)(1.963495 * 32768.0)) /* 5pi/8  */
+#define FREQ_EIAJ_DUAL		((s32)(2.562118 * 32768.0))
+#define FREQ_EIAJ_STEREO	((s32)(2.601053 * 32768.0))
+
+#define FREQ_BTSC_DUAL		((s32)(1.963495 * 32768.0)) /* 5pi/8  */
+#define FREQ_BTSC_DUAL_REF	((s32)(1.374446 * 32768.0)) /* 7pi/16 */
+
+#define FREQ_BTSC_SAP		((s32)(2.471532 * 32768.0))
+#define FREQ_BTSC_SAP_REF	((s32)(1.730072 * 32768.0))
+
+/* The spectrum of the signal should be empty between these frequencies. */
+#define FREQ_NOISE_START	((s32)(0.100000 * 32768.0))
+#define FREQ_NOISE_END		((s32)(1.200000 * 32768.0))
+
+static unsigned int dsp_debug;
+module_param(dsp_debug, int, 0644);
+MODULE_PARM_DESC(dsp_debug, "enable audio dsp debug messages");
+
+#define dprintk(level, fmt, arg...)	if (dsp_debug >= level) \
+	printk(KERN_DEBUG "%s/0: " fmt, core->name , ## arg)
+
+static s32 int_cos(u32 x)
+{
+	u32 t2, t4, t6, t8;
+	s32 ret;
+	u16 period = x / INT_PI;
+	if (period % 2)
+		return -int_cos(x - INT_PI);
+	x = x % INT_PI;
+	if (x > INT_PI/2)
+		return -int_cos(INT_PI/2 - (x % (INT_PI/2)));
+	/* Now x is between 0 and INT_PI/2.
+	 * To calculate cos(x) we use it's Taylor polinom. */
+	t2 = x*x/32768/2;
+	t4 = t2*x/32768*x/32768/3/4;
+	t6 = t4*x/32768*x/32768/5/6;
+	t8 = t6*x/32768*x/32768/7/8;
+	ret = 32768-t2+t4-t6+t8;
+	return ret;
+}
+
+static u32 int_goertzel(s16 x[], u32 N, u32 freq)
+{
+	/* We use the Goertzel algorithm to determine the power of the
+	 * given frequency in the signal */
+	s32 s_prev = 0;
+	s32 s_prev2 = 0;
+	s32 coeff = 2*int_cos(freq);
+	u32 i;
+	for (i = 0; i < N; i++) {
+		s32 s = x[i] + ((s64)coeff*s_prev/32768) - s_prev2;
+		s_prev2 = s_prev;
+		s_prev = s;
+	}
+	return (u32)(((s64)s_prev2*s_prev2 + (s64)s_prev*s_prev -
+		      (s64)coeff*s_prev2*s_prev/32768)/N/N);
+}
+
+static u32 freq_magnitude(s16 x[], u32 N, u32 freq)
+{
+	u32 sum = int_goertzel(x, N, freq);
+	return (u32)int_sqrt(sum);
+}
+
+static u32 noise_magnitude(s16 x[], u32 N, u32 freq_start, u32 freq_end)
+{
+	int i;
+	u32 sum = 0;
+	u32 freq_step;
+	int samples = 5;
+
+	if (N > 192) {
+		/* The last 192 samples are enough for noise detection */
+		x += (N-192);
+		N = 192;
+	}
+
+	freq_step = (freq_end - freq_start) / (samples - 1);
+
+	for (i = 0; i < samples; i++) {
+		sum += int_goertzel(x, N, freq_start);
+		freq_start += freq_step;
+	}
+
+	return (u32)int_sqrt(sum / samples);
+}
+
+static s32 detect_a2_a2m_eiaj(struct cx88_core *core, s16 x[], u32 N)
+{
+	s32 carrier, stereo, dual, noise;
+	s32 carrier_freq, stereo_freq, dual_freq;
+	s32 ret;
+
+	switch (core->tvaudio) {
+	case WW_BG:
+	case WW_DK:
+		carrier_freq = FREQ_A2_CARRIER;
+		stereo_freq = FREQ_A2_STEREO;
+		dual_freq = FREQ_A2_DUAL;
+		break;
+	case WW_M:
+		carrier_freq = FREQ_A2M_CARRIER;
+		stereo_freq = FREQ_A2M_STEREO;
+		dual_freq = FREQ_A2M_DUAL;
+		break;
+	case WW_EIAJ:
+		carrier_freq = FREQ_EIAJ_CARRIER;
+		stereo_freq = FREQ_EIAJ_STEREO;
+		dual_freq = FREQ_EIAJ_DUAL;
+		break;
+	default:
+		printk(KERN_WARNING "%s/0: unsupported audio mode %d for %s\n",
+		       core->name, core->tvaudio, __func__);
+		return UNSET;
+	}
+
+	carrier = freq_magnitude(x, N, carrier_freq);
+	stereo  = freq_magnitude(x, N, stereo_freq);
+	dual    = freq_magnitude(x, N, dual_freq);
+	noise   = noise_magnitude(x, N, FREQ_NOISE_START, FREQ_NOISE_END);
+
+	dprintk(1, "detect a2/a2m/eiaj: carrier=%d, stereo=%d, dual=%d, "
+		   "noise=%d\n", carrier, stereo, dual, noise);
+
+	if (stereo > dual)
+		ret = V4L2_TUNER_SUB_STEREO;
+	else
+		ret = V4L2_TUNER_SUB_LANG1 | V4L2_TUNER_SUB_LANG2;
+
+	if (core->tvaudio == WW_EIAJ) {
+		/* EIAJ checks may need adjustments */
+		if ((carrier > max(stereo, dual)*2) &&
+		    (carrier < max(stereo, dual)*6) &&
+		    (carrier > 20 && carrier < 200) &&
+		    (max(stereo, dual) > min(stereo, dual))) {
+			/* For EIAJ the carrier is always present,
+			   so we probably don't need noise detection */
+			return ret;
+		}
+	} else {
+		if ((carrier > max(stereo, dual)*2) &&
+		    (carrier < max(stereo, dual)*8) &&
+		    (carrier > 20 && carrier < 200) &&
+		    (noise < 10) &&
+		    (max(stereo, dual) > min(stereo, dual)*2)) {
+			return ret;
+		}
+	}
+	return V4L2_TUNER_SUB_MONO;
+}
+
+static s32 detect_btsc(struct cx88_core *core, s16 x[], u32 N)
+{
+	s32 sap_ref = freq_magnitude(x, N, FREQ_BTSC_SAP_REF);
+	s32 sap = freq_magnitude(x, N, FREQ_BTSC_SAP);
+	s32 dual_ref = freq_magnitude(x, N, FREQ_BTSC_DUAL_REF);
+	s32 dual = freq_magnitude(x, N, FREQ_BTSC_DUAL);
+	dprintk(1, "detect btsc: dual_ref=%d, dual=%d, sap_ref=%d, sap=%d"
+		   "\n", dual_ref, dual, sap_ref, sap);
+	/* FIXME: Currently not supported */
+	return UNSET;
+}
+
+static s16 *read_rds_samples(struct cx88_core *core, u32 *N)
+{
+	struct sram_channel *srch = &cx88_sram_channels[SRAM_CH27];
+	s16 *samples;
+
+	unsigned int i;
+	unsigned int bpl = srch->fifo_size/AUD_RDS_LINES;
+	unsigned int spl = bpl/4;
+	unsigned int sample_count = spl*(AUD_RDS_LINES-1);
+
+	u32 current_address = cx_read(srch->ptr1_reg);
+	u32 offset = (current_address - srch->fifo_start + bpl);
+
+	dprintk(1, "read RDS samples: current_address=%08x (offset=%08x), "
+		"sample_count=%d, aud_intstat=%08x\n", current_address,
+		current_address - srch->fifo_start, sample_count,
+		cx_read(MO_AUD_INTSTAT));
+
+	samples = kmalloc(sizeof(s16)*sample_count, GFP_KERNEL);
+	if (!samples)
+		return NULL;
+
+	*N = sample_count;
+
+	for (i = 0; i < sample_count; i++)  {
+		offset = offset % (AUD_RDS_LINES*bpl);
+		samples[i] = cx_read(srch->fifo_start + offset);
+		offset += 4;
+	}
+
+	if (dsp_debug >= 2) {
+		dprintk(2, "RDS samples dump: ");
+		for (i = 0; i < sample_count; i++)
+			printk("%hd ", samples[i]);
+		printk(".\n");
+	}
+
+	return samples;
+}
+
+s32 cx88_dsp_detect_stereo_sap(struct cx88_core *core)
+{
+	s16 *samples;
+	u32 N = 0;
+	s32 ret = UNSET;
+
+	/* If audio RDS fifo is disabled, we can't read the samples */
+	if (!(cx_read(MO_AUD_DMACNTRL) & 0x04))
+		return ret;
+	if (!(cx_read(AUD_CTL) & EN_FMRADIO_EN_RDS))
+		return ret;
+
+	/* Wait at least 500 ms after an audio standard change */
+	if (time_before(jiffies, core->last_change + msecs_to_jiffies(500)))
+		return ret;
+
+	samples = read_rds_samples(core, &N);
+
+	if (!samples)
+		return ret;
+
+	switch (core->tvaudio) {
+	case WW_BG:
+	case WW_DK:
+		ret = detect_a2_a2m_eiaj(core, samples, N);
+		break;
+	case WW_BTSC:
+		ret = detect_btsc(core, samples, N);
+		break;
+	}
+
+	kfree(samples);
+
+	if (UNSET != ret)
+		dprintk(1, "stereo/sap detection result:%s%s%s\n",
+			   (ret & V4L2_TUNER_SUB_MONO) ? " mono" : "",
+			   (ret & V4L2_TUNER_SUB_STEREO) ? " stereo" : "",
+			   (ret & V4L2_TUNER_SUB_LANG2) ? " dual" : "");
+
+	return ret;
+}
+EXPORT_SYMBOL(cx88_dsp_detect_stereo_sap);
+