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

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This source file includes following definitions.
int_cos
int_goertzel
freq_magnitude
noise_magnitude
detect_a2_a2m_eiaj
detect_btsc
read_rds_samples
cx88_dsp_detect_stereo_sap
   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Stereo and SAP detection for cx88
   4  *
   5  *  Copyright (c) 2009 Marton Balint <cus@fazekas.hu>
   6  */
   7 
   8 #include "cx88.h"
   9 #include "cx88-reg.h"
  10 
  11 #include <linux/slab.h>
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/jiffies.h>
  15 #include <asm/div64.h>
  16 
  17 #define INT_PI                  ((s32)(3.141592653589 * 32768.0))
  18 
  19 #define compat_remainder(a, b) \
  20          ((float)(((s32)((a) * 100)) % ((s32)((b) * 100))) / 100.0)
  21 
  22 #define baseband_freq(carrier, srate, tone) ((s32)( \
  23          (compat_remainder(carrier + tone, srate)) / srate * 2 * INT_PI))
  24 
  25 /*
  26  * We calculate the baseband frequencies of the carrier and the pilot tones
  27  * based on the the sampling rate of the audio rds fifo.
  28  */
  29 
  30 #define FREQ_A2_CARRIER         baseband_freq(54687.5, 2689.36, 0.0)
  31 #define FREQ_A2_DUAL            baseband_freq(54687.5, 2689.36, 274.1)
  32 #define FREQ_A2_STEREO          baseband_freq(54687.5, 2689.36, 117.5)
  33 
  34 /*
  35  * The frequencies below are from the reference driver. They probably need
  36  * further adjustments, because they are not tested at all. You may even need
  37  * to play a bit with the registers of the chip to select the proper signal
  38  * for the input of the audio rds fifo, and measure it's sampling rate to
  39  * calculate the proper baseband frequencies...
  40  */
  41 
  42 #define FREQ_A2M_CARRIER        ((s32)(2.114516 * 32768.0))
  43 #define FREQ_A2M_DUAL           ((s32)(2.754916 * 32768.0))
  44 #define FREQ_A2M_STEREO         ((s32)(2.462326 * 32768.0))
  45 
  46 #define FREQ_EIAJ_CARRIER       ((s32)(1.963495 * 32768.0)) /* 5pi/8  */
  47 #define FREQ_EIAJ_DUAL          ((s32)(2.562118 * 32768.0))
  48 #define FREQ_EIAJ_STEREO        ((s32)(2.601053 * 32768.0))
  49 
  50 #define FREQ_BTSC_DUAL          ((s32)(1.963495 * 32768.0)) /* 5pi/8  */
  51 #define FREQ_BTSC_DUAL_REF      ((s32)(1.374446 * 32768.0)) /* 7pi/16 */
  52 
  53 #define FREQ_BTSC_SAP           ((s32)(2.471532 * 32768.0))
  54 #define FREQ_BTSC_SAP_REF       ((s32)(1.730072 * 32768.0))
  55 
  56 /* The spectrum of the signal should be empty between these frequencies. */
  57 #define FREQ_NOISE_START        ((s32)(0.100000 * 32768.0))
  58 #define FREQ_NOISE_END          ((s32)(1.200000 * 32768.0))
  59 
  60 static unsigned int dsp_debug;
  61 module_param(dsp_debug, int, 0644);
  62 MODULE_PARM_DESC(dsp_debug, "enable audio dsp debug messages");
  63 
  64 #define dprintk(level, fmt, arg...) do {                                \
  65         if (dsp_debug >= level)                                         \
  66                 printk(KERN_DEBUG pr_fmt("%s: dsp:" fmt),               \
  67                         __func__, ##arg);                               \
  68 } while (0)
  69 
  70 static s32 int_cos(u32 x)
  71 {
  72         u32 t2, t4, t6, t8;
  73         s32 ret;
  74         u16 period = x / INT_PI;
  75 
  76         if (period % 2)
  77                 return -int_cos(x - INT_PI);
  78         x = x % INT_PI;
  79         if (x > INT_PI / 2)
  80                 return -int_cos(INT_PI / 2 - (x % (INT_PI / 2)));
  81         /*
  82          * Now x is between 0 and INT_PI/2.
  83          * To calculate cos(x) we use it's Taylor polinom.
  84          */
  85         t2 = x * x / 32768 / 2;
  86         t4 = t2 * x / 32768 * x / 32768 / 3 / 4;
  87         t6 = t4 * x / 32768 * x / 32768 / 5 / 6;
  88         t8 = t6 * x / 32768 * x / 32768 / 7 / 8;
  89         ret = 32768 - t2 + t4 - t6 + t8;
  90         return ret;
  91 }
  92 
  93 static u32 int_goertzel(s16 x[], u32 N, u32 freq)
  94 {
  95         /*
  96          * We use the Goertzel algorithm to determine the power of the
  97          * given frequency in the signal
  98          */
  99         s32 s_prev = 0;
 100         s32 s_prev2 = 0;
 101         s32 coeff = 2 * int_cos(freq);
 102         u32 i;
 103 
 104         u64 tmp;
 105         u32 divisor;
 106 
 107         for (i = 0; i < N; i++) {
 108                 s32 s = x[i] + ((s64)coeff * s_prev / 32768) - s_prev2;
 109 
 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         /*
 118          * XXX: N must be low enough so that N*N fits in s32.
 119          * Else we need two divisions.
 120          */
 121         divisor = N * N;
 122         do_div(tmp, divisor);
 123 
 124         return (u32)tmp;
 125 }
 126 
 127 static u32 freq_magnitude(s16 x[], u32 N, u32 freq)
 128 {
 129         u32 sum = int_goertzel(x, N, freq);
 130 
 131         return (u32)int_sqrt(sum);
 132 }
 133 
 134 static u32 noise_magnitude(s16 x[], u32 N, u32 freq_start, u32 freq_end)
 135 {
 136         int i;
 137         u32 sum = 0;
 138         u32 freq_step;
 139         int samples = 5;
 140 
 141         if (N > 192) {
 142                 /* The last 192 samples are enough for noise detection */
 143                 x += (N - 192);
 144                 N = 192;
 145         }
 146 
 147         freq_step = (freq_end - freq_start) / (samples - 1);
 148 
 149         for (i = 0; i < samples; i++) {
 150                 sum += int_goertzel(x, N, freq_start);
 151                 freq_start += freq_step;
 152         }
 153 
 154         return (u32)int_sqrt(sum / samples);
 155 }
 156 
 157 static s32 detect_a2_a2m_eiaj(struct cx88_core *core, s16 x[], u32 N)
 158 {
 159         s32 carrier, stereo, dual, noise;
 160         s32 carrier_freq, stereo_freq, dual_freq;
 161         s32 ret;
 162 
 163         switch (core->tvaudio) {
 164         case WW_BG:
 165         case WW_DK:
 166                 carrier_freq = FREQ_A2_CARRIER;
 167                 stereo_freq = FREQ_A2_STEREO;
 168                 dual_freq = FREQ_A2_DUAL;
 169                 break;
 170         case WW_M:
 171                 carrier_freq = FREQ_A2M_CARRIER;
 172                 stereo_freq = FREQ_A2M_STEREO;
 173                 dual_freq = FREQ_A2M_DUAL;
 174                 break;
 175         case WW_EIAJ:
 176                 carrier_freq = FREQ_EIAJ_CARRIER;
 177                 stereo_freq = FREQ_EIAJ_STEREO;
 178                 dual_freq = FREQ_EIAJ_DUAL;
 179                 break;
 180         default:
 181                 pr_warn("unsupported audio mode %d for %s\n",
 182                         core->tvaudio, __func__);
 183                 return UNSET;
 184         }
 185 
 186         carrier = freq_magnitude(x, N, carrier_freq);
 187         stereo  = freq_magnitude(x, N, stereo_freq);
 188         dual    = freq_magnitude(x, N, dual_freq);
 189         noise   = noise_magnitude(x, N, FREQ_NOISE_START, FREQ_NOISE_END);
 190 
 191         dprintk(1,
 192                 "detect a2/a2m/eiaj: carrier=%d, stereo=%d, dual=%d, noise=%d\n",
 193                 carrier, stereo, dual, noise);
 194 
 195         if (stereo > dual)
 196                 ret = V4L2_TUNER_SUB_STEREO;
 197         else
 198                 ret = V4L2_TUNER_SUB_LANG1 | V4L2_TUNER_SUB_LANG2;
 199 
 200         if (core->tvaudio == WW_EIAJ) {
 201                 /* EIAJ checks may need adjustments */
 202                 if ((carrier > max(stereo, dual) * 2) &&
 203                     (carrier < max(stereo, dual) * 6) &&
 204                     (carrier > 20 && carrier < 200) &&
 205                     (max(stereo, dual) > min(stereo, dual))) {
 206                         /*
 207                          * For EIAJ the carrier is always present,
 208                          * so we probably don't need noise detection
 209                          */
 210                         return ret;
 211                 }
 212         } else {
 213                 if ((carrier > max(stereo, dual) * 2) &&
 214                     (carrier < max(stereo, dual) * 8) &&
 215                     (carrier > 20 && carrier < 200) &&
 216                     (noise < 10) &&
 217                     (max(stereo, dual) > min(stereo, dual) * 2)) {
 218                         return ret;
 219                 }
 220         }
 221         return V4L2_TUNER_SUB_MONO;
 222 }
 223 
 224 static s32 detect_btsc(struct cx88_core *core, s16 x[], u32 N)
 225 {
 226         s32 sap_ref = freq_magnitude(x, N, FREQ_BTSC_SAP_REF);
 227         s32 sap = freq_magnitude(x, N, FREQ_BTSC_SAP);
 228         s32 dual_ref = freq_magnitude(x, N, FREQ_BTSC_DUAL_REF);
 229         s32 dual = freq_magnitude(x, N, FREQ_BTSC_DUAL);
 230 
 231         dprintk(1, "detect btsc: dual_ref=%d, dual=%d, sap_ref=%d, sap=%d\n",
 232                 dual_ref, dual, sap_ref, sap);
 233         /* FIXME: Currently not supported */
 234         return UNSET;
 235 }
 236 
 237 static s16 *read_rds_samples(struct cx88_core *core, u32 *N)
 238 {
 239         const struct sram_channel *srch = &cx88_sram_channels[SRAM_CH27];
 240         s16 *samples;
 241 
 242         unsigned int i;
 243         unsigned int bpl = srch->fifo_size / AUD_RDS_LINES;
 244         unsigned int spl = bpl / 4;
 245         unsigned int sample_count = spl * (AUD_RDS_LINES - 1);
 246 
 247         u32 current_address = cx_read(srch->ptr1_reg);
 248         u32 offset = (current_address - srch->fifo_start + bpl);
 249 
 250         dprintk(1,
 251                 "read RDS samples: current_address=%08x (offset=%08x), sample_count=%d, aud_intstat=%08x\n",
 252                 current_address,
 253                 current_address - srch->fifo_start, sample_count,
 254                 cx_read(MO_AUD_INTSTAT));
 255         samples = kmalloc_array(sample_count, sizeof(*samples), GFP_KERNEL);
 256         if (!samples)
 257                 return NULL;
 258 
 259         *N = sample_count;
 260 
 261         for (i = 0; i < sample_count; i++)  {
 262                 offset = offset % (AUD_RDS_LINES * bpl);
 263                 samples[i] = cx_read(srch->fifo_start + offset);
 264                 offset += 4;
 265         }
 266 
 267         dprintk(2, "RDS samples dump: %*ph\n", sample_count, samples);
 268 
 269         return samples;
 270 }
 271 
 272 s32 cx88_dsp_detect_stereo_sap(struct cx88_core *core)
 273 {
 274         s16 *samples;
 275         u32 N = 0;
 276         s32 ret = UNSET;
 277 
 278         /* If audio RDS fifo is disabled, we can't read the samples */
 279         if (!(cx_read(MO_AUD_DMACNTRL) & 0x04))
 280                 return ret;
 281         if (!(cx_read(AUD_CTL) & EN_FMRADIO_EN_RDS))
 282                 return ret;
 283 
 284         /* Wait at least 500 ms after an audio standard change */
 285         if (time_before(jiffies, core->last_change + msecs_to_jiffies(500)))
 286                 return ret;
 287 
 288         samples = read_rds_samples(core, &N);
 289 
 290         if (!samples)
 291                 return ret;
 292 
 293         switch (core->tvaudio) {
 294         case WW_BG:
 295         case WW_DK:
 296         case WW_EIAJ:
 297         case WW_M:
 298                 ret = detect_a2_a2m_eiaj(core, samples, N);
 299                 break;
 300         case WW_BTSC:
 301                 ret = detect_btsc(core, samples, N);
 302                 break;
 303         case WW_NONE:
 304         case WW_I:
 305         case WW_L:
 306         case WW_I2SPT:
 307         case WW_FM:
 308         case WW_I2SADC:
 309                 break;
 310         }
 311 
 312         kfree(samples);
 313 
 314         if (ret != UNSET)
 315                 dprintk(1, "stereo/sap detection result:%s%s%s\n",
 316                         (ret & V4L2_TUNER_SUB_MONO) ? " mono" : "",
 317                         (ret & V4L2_TUNER_SUB_STEREO) ? " stereo" : "",
 318                         (ret & V4L2_TUNER_SUB_LANG2) ? " dual" : "");
 319 
 320         return ret;
 321 }
 322 EXPORT_SYMBOL(cx88_dsp_detect_stereo_sap);
 323
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root/drivers/media/pci/cx88/cx88-dsp.c

DEFINITIONS
