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