LXR linux/drivers/media/pci/cx88/cx88-dsp.c

   1/*
   2 *  Stereo and SAP detection for cx88
   3 *
   4 *  Copyright (c) 2009 Marton Balint <cus@fazekas.hu>
   5 *
   6 *  This program is free software; you can redistribute it and/or modify
   7 *  it under the terms of the GNU General Public License as published by
   8 *  the Free Software Foundation; either version 2 of the License, or
   9 *  (at your option) any later version.
  10 *
  11 *  This program is distributed in the hope that it will be useful,
  12 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 *  GNU General Public License for more details.
  15 */
  16
  17#include "cx88.h"
  18#include "cx88-reg.h"
  19
  20#include <linux/slab.h>
  21#include <linux/kernel.h>
  22#include <linux/module.h>
  23#include <linux/jiffies.h>
  24#include <asm/div64.h>
  25
  26#define INT_PI                  ((s32)(3.141592653589 * 32768.0))
  27
  28#define compat_remainder(a, b) \
  29         ((float)(((s32)((a) * 100)) % ((s32)((b) * 100))) / 100.0)
  30
  31#define baseband_freq(carrier, srate, tone) ((s32)( \
  32         (compat_remainder(carrier + tone, srate)) / srate * 2 * INT_PI))
  33
  34/*
  35 * We calculate the baseband frequencies of the carrier and the pilot tones
  36 * based on the the sampling rate of the audio rds fifo.
  37 */
  38
  39#define FREQ_A2_CARRIER         baseband_freq(54687.5, 2689.36, 0.0)
  40#define FREQ_A2_DUAL            baseband_freq(54687.5, 2689.36, 274.1)
  41#define FREQ_A2_STEREO          baseband_freq(54687.5, 2689.36, 117.5)
  42
  43/*
  44 * The frequencies below are from the reference driver. They probably need
  45 * further adjustments, because they are not tested at all. You may even need
  46 * to play a bit with the registers of the chip to select the proper signal
  47 * for the input of the audio rds fifo, and measure it's sampling rate to
  48 * calculate the proper baseband frequencies...
  49 */
  50
  51#define FREQ_A2M_CARRIER        ((s32)(2.114516 * 32768.0))
  52#define FREQ_A2M_DUAL           ((s32)(2.754916 * 32768.0))
  53#define FREQ_A2M_STEREO         ((s32)(2.462326 * 32768.0))
  54
  55#define FREQ_EIAJ_CARRIER       ((s32)(1.963495 * 32768.0)) /* 5pi/8  */
  56#define FREQ_EIAJ_DUAL          ((s32)(2.562118 * 32768.0))
  57#define FREQ_EIAJ_STEREO        ((s32)(2.601053 * 32768.0))
  58
  59#define FREQ_BTSC_DUAL          ((s32)(1.963495 * 32768.0)) /* 5pi/8  */
  60#define FREQ_BTSC_DUAL_REF      ((s32)(1.374446 * 32768.0)) /* 7pi/16 */
  61
  62#define FREQ_BTSC_SAP           ((s32)(2.471532 * 32768.0))
  63#define FREQ_BTSC_SAP_REF       ((s32)(1.730072 * 32768.0))
  64
  65/* The spectrum of the signal should be empty between these frequencies. */
  66#define FREQ_NOISE_START        ((s32)(0.100000 * 32768.0))
  67#define FREQ_NOISE_END          ((s32)(1.200000 * 32768.0))
  68
  69static unsigned int dsp_debug;
  70module_param(dsp_debug, int, 0644);
  71MODULE_PARM_DESC(dsp_debug, "enable audio dsp debug messages");
  72
  73#define dprintk(level, fmt, arg...) do {                                \
  74        if (dsp_debug >= level)                                         \
  75                printk(KERN_DEBUG pr_fmt("%s: dsp:" fmt),               \
  76                        __func__, ##arg);                               \
  77} while (0)
  78
  79static s32 int_cos(u32 x)
  80{
  81        u32 t2, t4, t6, t8;
  82        s32 ret;
  83        u16 period = x / INT_PI;
  84
  85        if (period % 2)
  86                return -int_cos(x - INT_PI);
  87        x = x % INT_PI;
  88        if (x > INT_PI / 2)
  89                return -int_cos(INT_PI / 2 - (x % (INT_PI / 2)));
  90        /*
  91         * Now x is between 0 and INT_PI/2.
  92         * To calculate cos(x) we use it's Taylor polinom.
  93         */
  94        t2 = x * x / 32768 / 2;
  95        t4 = t2 * x / 32768 * x / 32768 / 3 / 4;
  96        t6 = t4 * x / 32768 * x / 32768 / 5 / 6;
  97        t8 = t6 * x / 32768 * x / 32768 / 7 / 8;
  98        ret = 32768 - t2 + t4 - t6 + t8;
  99        return ret;
 100}
 101
 102static u32 int_goertzel(s16 x[], u32 N, u32 freq)
 103{
 104        /*
 105         * We use the Goertzel algorithm to determine the power of the
 106         * given frequency in the signal
 107         */
 108        s32 s_prev = 0;
 109        s32 s_prev2 = 0;
 110        s32 coeff = 2 * int_cos(freq);
 111        u32 i;
 112
 113        u64 tmp;
 114        u32 divisor;
 115
 116        for (i = 0; i < N; i++) {
 117                s32 s = x[i] + ((s64)coeff * s_prev / 32768) - s_prev2;
 118
 119                s_prev2 = s_prev;
 120                s_prev = s;
 121        }
 122
 123        tmp = (s64)s_prev2 * s_prev2 + (s64)s_prev * s_prev -
 124                      (s64)coeff * s_prev2 * s_prev / 32768;
 125
 126        /*
 127         * XXX: N must be low enough so that N*N fits in s32.
 128         * Else we need two divisions.
 129         */
 130        divisor = N * N;
 131        do_div(tmp, divisor);
 132
 133        return (u32)tmp;
 134}
 135
 136static u32 freq_magnitude(s16 x[], u32 N, u32 freq)
 137{
 138        u32 sum = int_goertzel(x, N, freq);
 139
 140        return (u32)int_sqrt(sum);
 141}
 142
 143static u32 noise_magnitude(s16 x[], u32 N, u32 freq_start, u32 freq_end)
 144{
 145        int i;
 146        u32 sum = 0;
 147        u32 freq_step;
 148        int samples = 5;
 149
 150        if (N > 192) {
 151                /* The last 192 samples are enough for noise detection */
 152                x += (N - 192);
 153                N = 192;
 154        }
 155
 156        freq_step = (freq_end - freq_start) / (samples - 1);
 157
 158        for (i = 0; i < samples; i++) {
 159                sum += int_goertzel(x, N, freq_start);
 160                freq_start += freq_step;
 161        }
 162
 163        return (u32)int_sqrt(sum / samples);
 164}
 165
 166static s32 detect_a2_a2m_eiaj(struct cx88_core *core, s16 x[], u32 N)
 167{
 168        s32 carrier, stereo, dual, noise;
 169        s32 carrier_freq, stereo_freq, dual_freq;
 170        s32 ret;
 171
 172        switch (core->tvaudio) {
 173        case WW_BG:
 174        case WW_DK:
 175                carrier_freq = FREQ_A2_CARRIER;
 176                stereo_freq = FREQ_A2_STEREO;
 177                dual_freq = FREQ_A2_DUAL;
 178                break;
 179        case WW_M:
 180                carrier_freq = FREQ_A2M_CARRIER;
 181                stereo_freq = FREQ_A2M_STEREO;
 182                dual_freq = FREQ_A2M_DUAL;
 183                break;
 184        case WW_EIAJ:
 185                carrier_freq = FREQ_EIAJ_CARRIER;
 186                stereo_freq = FREQ_EIAJ_STEREO;
 187                dual_freq = FREQ_EIAJ_DUAL;
 188                break;
 189        default:
 190                pr_warn("unsupported audio mode %d for %s\n",
 191                        core->tvaudio, __func__);
 192                return UNSET;
 193        }
 194
 195        carrier = freq_magnitude(x, N, carrier_freq);
 196        stereo  = freq_magnitude(x, N, stereo_freq);
 197        dual    = freq_magnitude(x, N, dual_freq);
 198        noise   = noise_magnitude(x, N, FREQ_NOISE_START, FREQ_NOISE_END);
 199
 200        dprintk(1,
 201                "detect a2/a2m/eiaj: carrier=%d, stereo=%d, dual=%d, noise=%d\n",
 202                carrier, stereo, dual, noise);
 203
 204        if (stereo > dual)
 205                ret = V4L2_TUNER_SUB_STEREO;
 206        else
 207                ret = V4L2_TUNER_SUB_LANG1 | V4L2_TUNER_SUB_LANG2;
 208
 209        if (core->tvaudio == WW_EIAJ) {
 210                /* EIAJ checks may need adjustments */
 211                if ((carrier > max(stereo, dual) * 2) &&
 212                    (carrier < max(stereo, dual) * 6) &&
 213                    (carrier > 20 && carrier < 200) &&
 214                    (max(stereo, dual) > min(stereo, dual))) {
 215                        /*
 216                         * For EIAJ the carrier is always present,
 217                         * so we probably don't need noise detection
 218                         */
 219                        return ret;
 220                }
 221        } else {
 222                if ((carrier > max(stereo, dual) * 2) &&
 223                    (carrier < max(stereo, dual) * 8) &&
 224                    (carrier > 20 && carrier < 200) &&
 225                    (noise < 10) &&
 226                    (max(stereo, dual) > min(stereo, dual) * 2)) {
 227                        return ret;
 228                }
 229        }
 230        return V4L2_TUNER_SUB_MONO;
 231}
 232
 233static s32 detect_btsc(struct cx88_core *core, s16 x[], u32 N)
 234{
 235        s32 sap_ref = freq_magnitude(x, N, FREQ_BTSC_SAP_REF);
 236        s32 sap = freq_magnitude(x, N, FREQ_BTSC_SAP);
 237        s32 dual_ref = freq_magnitude(x, N, FREQ_BTSC_DUAL_REF);
 238        s32 dual = freq_magnitude(x, N, FREQ_BTSC_DUAL);
 239
 240        dprintk(1, "detect btsc: dual_ref=%d, dual=%d, sap_ref=%d, sap=%d\n",
 241                dual_ref, dual, sap_ref, sap);
 242        /* FIXME: Currently not supported */
 243        return UNSET;
 244}
 245
 246static s16 *read_rds_samples(struct cx88_core *core, u32 *N)
 247{
 248        const struct sram_channel *srch = &cx88_sram_channels[SRAM_CH27];
 249        s16 *samples;
 250
 251        unsigned int i;
 252        unsigned int bpl = srch->fifo_size / AUD_RDS_LINES;
 253        unsigned int spl = bpl / 4;
 254        unsigned int sample_count = spl * (AUD_RDS_LINES - 1);
 255
 256        u32 current_address = cx_read(srch->ptr1_reg);
 257        u32 offset = (current_address - srch->fifo_start + bpl);
 258
 259        dprintk(1,
 260                "read RDS samples: current_address=%08x (offset=%08x), sample_count=%d, aud_intstat=%08x\n",
 261                current_address,
 262                current_address - srch->fifo_start, sample_count,
 263                cx_read(MO_AUD_INTSTAT));
 264        samples = kmalloc_array(sample_count, sizeof(*samples), GFP_KERNEL);
 265        if (!samples)
 266                return NULL;
 267
 268        *N = sample_count;
 269
 270        for (i = 0; i < sample_count; i++)  {
 271                offset = offset % (AUD_RDS_LINES * bpl);
 272                samples[i] = cx_read(srch->fifo_start + offset);
 273                offset += 4;
 274        }
 275
 276        dprintk(2, "RDS samples dump: %*ph\n", sample_count, samples);
 277
 278        return samples;
 279}
 280
 281s32 cx88_dsp_detect_stereo_sap(struct cx88_core *core)
 282{
 283        s16 *samples;
 284        u32 N = 0;
 285        s32 ret = UNSET;
 286
 287        /* If audio RDS fifo is disabled, we can't read the samples */
 288        if (!(cx_read(MO_AUD_DMACNTRL) & 0x04))
 289                return ret;
 290        if (!(cx_read(AUD_CTL) & EN_FMRADIO_EN_RDS))
 291                return ret;
 292
 293        /* Wait at least 500 ms after an audio standard change */
 294        if (time_before(jiffies, core->last_change + msecs_to_jiffies(500)))
 295                return ret;
 296
 297        samples = read_rds_samples(core, &N);
 298
 299        if (!samples)
 300                return ret;
 301
 302        switch (core->tvaudio) {
 303        case WW_BG:
 304        case WW_DK:
 305        case WW_EIAJ:
 306        case WW_M:
 307                ret = detect_a2_a2m_eiaj(core, samples, N);
 308                break;
 309        case WW_BTSC:
 310                ret = detect_btsc(core, samples, N);
 311                break;
 312        case WW_NONE:
 313        case WW_I:
 314        case WW_L:
 315        case WW_I2SPT:
 316        case WW_FM:
 317        case WW_I2SADC:
 318                break;
 319        }
 320
 321        kfree(samples);
 322
 323        if (ret != UNSET)
 324                dprintk(1, "stereo/sap detection result:%s%s%s\n",
 325                        (ret & V4L2_TUNER_SUB_MONO) ? " mono" : "",
 326                        (ret & V4L2_TUNER_SUB_STEREO) ? " stereo" : "",
 327                        (ret & V4L2_TUNER_SUB_LANG2) ? " dual" : "");
 328
 329        return ret;
 330}
 331EXPORT_SYMBOL(cx88_dsp_detect_stereo_sap);
 332
 333