drivers/media/video/cx88/cx88-dsp.c

   1 /*
   2  *
   3  *  Stereo and SAP detection for cx88
   4  *
   5  *  Copyright (c) 2009 Marton Balint <cus@fazekas.hu>
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation; either version 2 of the License, or
  10  *  (at your option) any later version.
  11  *
  12  *  This program is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License
  18  *  along with this program; if not, write to the Free Software
  19  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/jiffies.h>
  25 #include <asm/div64.h>
  26
  27 #include "cx88.h"
  28 #include "cx88-reg.h"
  29
  30 #define INT_PI                  ((s32)(3.141592653589 * 32768.0))
  31
  32 #define compat_remainder(a, b) \
  33          ((float)(((s32)((a)*100))%((s32)((b)*100)))/100.0)
  34
  35 #define baseband_freq(carrier, srate, tone) ((s32)( \
  36          (compat_remainder(carrier + tone, srate)) / srate * 2 * INT_PI))
  37
  38 /* We calculate the baseband frequencies of the carrier and the pilot tones
  39  * based on the the sampling rate of the audio rds fifo. */
  40
  41 #define FREQ_A2_CARRIER         baseband_freq(54687.5, 2689.36, 0.0)
  42 #define FREQ_A2_DUAL            baseband_freq(54687.5, 2689.36, 274.1)
  43 #define FREQ_A2_STEREO          baseband_freq(54687.5, 2689.36, 117.5)
  44
  45 /* The frequencies below are from the reference driver. They probably need
  46  * further adjustments, because they are not tested at all. You may even need
  47  * to play a bit with the registers of the chip to select the proper signal
  48  * for the input of the audio rds fifo, and measure it's sampling rate to
  49  * calculate the proper baseband frequencies... */
  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
  69 static unsigned int dsp_debug;
  70 module_param(dsp_debug, int, 0644);
  71 MODULE_PARM_DESC(dsp_debug, "enable audio dsp debug messages");
  72
  73 #define dprintk(level, fmt, arg...)     if (dsp_debug >= level) \
  74         printk(KERN_DEBUG "%s/0: " fmt, core->name , ## arg)
  75
  76 static s32 int_cos(u32 x)
  77 {
  78         u32 t2, t4, t6, t8;
  79         s32 ret;
  80         u16 period = x / INT_PI;
  81         if (period % 2)
  82                 return -int_cos(x - INT_PI);
  83         x = x % INT_PI;
  84         if (x > INT_PI/2)
  85                 return -int_cos(INT_PI/2 - (x % (INT_PI/2)));
  86         /* Now x is between 0 and INT_PI/2.
  87          * To calculate cos(x) we use it's Taylor polinom. */
  88         t2 = x*x/32768/2;
  89         t4 = t2*x/32768*x/32768/3/4;
  90         t6 = t4*x/32768*x/32768/5/6;
  91         t8 = t6*x/32768*x/32768/7/8;
  92         ret = 32768-t2+t4-t6+t8;
  93         return ret;
  94 }
  95
  96 static u32 int_goertzel(s16 x[], u32 N, u32 freq)
  97 {
  98         /* We use the Goertzel algorithm to determine the power of the
  99          * given frequency in the signal */
 100         s32 s_prev = 0;
 101         s32 s_prev2 = 0;
 102         s32 coeff = 2*int_cos(freq);
 103         u32 i;
 104
 105         u64 tmp;
 106         u32 divisor;
 107
 108         for (i = 0; i < N; i++) {
 109                 s32 s = x[i] + ((s64)coeff*s_prev/32768) - s_prev2;
 110                 s_prev2 = s_prev;
 111                 s_prev = s;
 112         }
 113
 114         tmp = (s64)s_prev2 * s_prev2 + (s64)s_prev * s_prev -
 115                       (s64)coeff * s_prev2 * s_prev / 32768;
 116
 117         /* XXX: N must be low enough so that N*N fits in s32.
 118          * Else we need two divisions. */
 119         divisor = N * N;
 120         do_div(tmp, divisor);
 121
 122         return (u32) tmp;
 123 }
 124
 125 static u32 freq_magnitude(s16 x[], u32 N, u32 freq)
 126 {
 127         u32 sum = int_goertzel(x, N, freq);
 128         return (u32)int_sqrt(sum);
 129 }
 130
 131 static u32 noise_magnitude(s16 x[], u32 N, u32 freq_start, u32 freq_end)
 132 {
 133         int i;
 134         u32 sum = 0;
 135         u32 freq_step;
 136         int samples = 5;
 137
 138         if (N > 192) {
 139                 /* The last 192 samples are enough for noise detection */
 140                 x += (N-192);
 141                 N = 192;
 142         }
 143
 144         freq_step = (freq_end - freq_start) / (samples - 1);
 145
 146         for (i = 0; i < samples; i++) {
 147                 sum += int_goertzel(x, N, freq_start);
 148                 freq_start += freq_step;
 149         }
 150
 151         return (u32)int_sqrt(sum / samples);
 152 }
 153
 154 static s32 detect_a2_a2m_eiaj(struct cx88_core *core, s16 x[], u32 N)
 155 {
 156         s32 carrier, stereo, dual, noise;
 157         s32 carrier_freq, stereo_freq, dual_freq;
 158         s32 ret;
 159
 160         switch (core->tvaudio) {
 161         case WW_BG:
 162         case WW_DK:
 163                 carrier_freq = FREQ_A2_CARRIER;
 164                 stereo_freq = FREQ_A2_STEREO;
 165                 dual_freq = FREQ_A2_DUAL;
 166                 break;
 167         case WW_M:
 168                 carrier_freq = FREQ_A2M_CARRIER;
 169                 stereo_freq = FREQ_A2M_STEREO;
 170                 dual_freq = FREQ_A2M_DUAL;
 171                 break;
 172         case WW_EIAJ:
 173                 carrier_freq = FREQ_EIAJ_CARRIER;
 174                 stereo_freq = FREQ_EIAJ_STEREO;
 175                 dual_freq = FREQ_EIAJ_DUAL;
 176                 break;
 177         default:
 178                 printk(KERN_WARNING "%s/0: unsupported audio mode %d for %s\n",
 179                        core->name, core->tvaudio, __func__);
 180                 return UNSET;
 181         }
 182
 183         carrier = freq_magnitude(x, N, carrier_freq);
 184         stereo  = freq_magnitude(x, N, stereo_freq);
 185         dual    = freq_magnitude(x, N, dual_freq);
 186         noise   = noise_magnitude(x, N, FREQ_NOISE_START, FREQ_NOISE_END);
 187
 188         dprintk(1, "detect a2/a2m/eiaj: carrier=%d, stereo=%d, dual=%d, "
 189                    "noise=%d\n", carrier, stereo, dual, noise);
 190
 191         if (stereo > dual)
 192                 ret = V4L2_TUNER_SUB_STEREO;
 193         else
 194                 ret = V4L2_TUNER_SUB_LANG1 | V4L2_TUNER_SUB_LANG2;
 195
 196         if (core->tvaudio == WW_EIAJ) {
 197                 /* EIAJ checks may need adjustments */
 198                 if ((carrier > max(stereo, dual)*2) &&
 199                     (carrier < max(stereo, dual)*6) &&
 200                     (carrier > 20 && carrier < 200) &&
 201                     (max(stereo, dual) > min(stereo, dual))) {
 202                         /* For EIAJ the carrier is always present,
 203                            so we probably don't need noise detection */
 204                         return ret;
 205                 }
 206         } else {
 207                 if ((carrier > max(stereo, dual)*2) &&
 208                     (carrier < max(stereo, dual)*8) &&
 209                     (carrier > 20 && carrier < 200) &&
 210                     (noise < 10) &&
 211                     (max(stereo, dual) > min(stereo, dual)*2)) {
 212                         return ret;
 213                 }
 214         }
 215         return V4L2_TUNER_SUB_MONO;
 216 }
 217
 218 static s32 detect_btsc(struct cx88_core *core, s16 x[], u32 N)
 219 {
 220         s32 sap_ref = freq_magnitude(x, N, FREQ_BTSC_SAP_REF);
 221         s32 sap = freq_magnitude(x, N, FREQ_BTSC_SAP);
 222         s32 dual_ref = freq_magnitude(x, N, FREQ_BTSC_DUAL_REF);
 223         s32 dual = freq_magnitude(x, N, FREQ_BTSC_DUAL);
 224         dprintk(1, "detect btsc: dual_ref=%d, dual=%d, sap_ref=%d, sap=%d"
 225                    "\n", dual_ref, dual, sap_ref, sap);
 226         /* FIXME: Currently not supported */
 227         return UNSET;
 228 }
 229
 230 static s16 *read_rds_samples(struct cx88_core *core, u32 *N)
 231 {
 232         struct sram_channel *srch = &cx88_sram_channels[SRAM_CH27];
 233         s16 *samples;
 234
 235         unsigned int i;
 236         unsigned int bpl = srch->fifo_size/AUD_RDS_LINES;
 237         unsigned int spl = bpl/4;
 238         unsigned int sample_count = spl*(AUD_RDS_LINES-1);
 239
 240         u32 current_address = cx_read(srch->ptr1_reg);
 241         u32 offset = (current_address - srch->fifo_start + bpl);
 242
 243         dprintk(1, "read RDS samples: current_address=%08x (offset=%08x), "
 244                 "sample_count=%d, aud_intstat=%08x\n", current_address,
 245                 current_address - srch->fifo_start, sample_count,
 246                 cx_read(MO_AUD_INTSTAT));
 247
 248         samples = kmalloc(sizeof(s16)*sample_count, GFP_KERNEL);
 249         if (!samples)
 250                 return NULL;
 251
 252         *N = sample_count;
 253
 254         for (i = 0; i < sample_count; i++)  {
 255                 offset = offset % (AUD_RDS_LINES*bpl);
 256                 samples[i] = cx_read(srch->fifo_start + offset);
 257                 offset += 4;
 258         }
 259
 260         if (dsp_debug >= 2) {
 261                 dprintk(2, "RDS samples dump: ");
 262                 for (i = 0; i < sample_count; i++)
 263                         printk("%hd ", samples[i]);
 264                 printk(".\n");
 265         }
 266
 267         return samples;
 268 }
 269
 270 s32 cx88_dsp_detect_stereo_sap(struct cx88_core *core)
 271 {
 272         s16 *samples;
 273         u32 N = 0;
 274         s32 ret = UNSET;
 275
 276         /* If audio RDS fifo is disabled, we can't read the samples */
 277         if (!(cx_read(MO_AUD_DMACNTRL) & 0x04))
 278                 return ret;
 279         if (!(cx_read(AUD_CTL) & EN_FMRADIO_EN_RDS))
 280                 return ret;
 281
 282         /* Wait at least 500 ms after an audio standard change */
 283         if (time_before(jiffies, core->last_change + msecs_to_jiffies(500)))
 284                 return ret;
 285
 286         samples = read_rds_samples(core, &N);
 287
 288         if (!samples)
 289                 return ret;
 290
 291         switch (core->tvaudio) {
 292         case WW_BG:
 293         case WW_DK:
 294                 ret = detect_a2_a2m_eiaj(core, samples, N);
 295                 break;
 296         case WW_BTSC:
 297                 ret = detect_btsc(core, samples, N);
 298                 break;
 299         }
 300
 301         kfree(samples);
 302
 303         if (UNSET != ret)
 304                 dprintk(1, "stereo/sap detection result:%s%s%s\n",
 305                            (ret & V4L2_TUNER_SUB_MONO) ? " mono" : "",
 306                            (ret & V4L2_TUNER_SUB_STEREO) ? " stereo" : "",
 307                            (ret & V4L2_TUNER_SUB_LANG2) ? " dual" : "");
 308
 309         return ret;
 310 }
 311 EXPORT_SYMBOL(cx88_dsp_detect_stereo_sap);
 312