--- /dev/null
+/*
+ *
+ * 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/slab.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/jiffies.h>
+#include <asm/div64.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;
+
+ u64 tmp;
+ u32 divisor;
+
+ for (i = 0; i < N; i++) {
+ s32 s = x[i] + ((s64)coeff*s_prev/32768) - s_prev2;
+ s_prev2 = s_prev;
+ s_prev = s;
+ }
+
+ tmp = (s64)s_prev2 * s_prev2 + (s64)s_prev * s_prev -
+ (s64)coeff * s_prev2 * s_prev / 32768;
+
+ /* XXX: N must be low enough so that N*N fits in s32.
+ * Else we need two divisions. */
+ divisor = N * N;
+ do_div(tmp, divisor);
+
+ return (u32) tmp;
+}
+
+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)
+{
+ const 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:
+ case WW_EIAJ:
+ case WW_M:
+ ret = detect_a2_a2m_eiaj(core, samples, N);
+ break;
+ case WW_BTSC:
+ ret = detect_btsc(core, samples, N);
+ break;
+ case WW_NONE:
+ case WW_I:
+ case WW_L:
+ case WW_I2SPT:
+ case WW_FM:
+ case WW_I2SADC:
+ 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);
+
Code Review / kvmfornfv.git / blobdiff