sound/core/pcm_iec958.c

   1 /*
   2  *  PCM DRM helpers
   3  *
   4  *   This program is free software; you can redistribute it and/or modify
   5  *   it under the terms of the GNU General Public License version 2 as
   6  *   published by the Free Software Foundation.
   7  */
   8 #include <linux/export.h>
   9 #include <linux/types.h>
  10 #include <sound/asoundef.h>
  11 #include <sound/pcm.h>
  12 #include <sound/pcm_iec958.h>
  13
  14 /**
  15  * snd_pcm_create_iec958_consumer - create consumer format IEC958 channel status
  16  * @runtime: pcm runtime structure with ->rate filled in
  17  * @cs: channel status buffer, at least four bytes
  18  * @len: length of channel status buffer
  19  *
  20  * Create the consumer format channel status data in @cs of maximum size
  21  * @len corresponding to the parameters of the PCM runtime @runtime.
  22  *
  23  * Drivers may wish to tweak the contents of the buffer after creation.
  24  *
  25  * Returns: length of buffer, or negative error code if something failed.
  26  */
  27 int snd_pcm_create_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
  28         size_t len)
  29 {
  30         unsigned int fs, ws;
  31
  32         if (len < 4)
  33                 return -EINVAL;
  34
  35         switch (runtime->rate) {
  36         case 32000:
  37                 fs = IEC958_AES3_CON_FS_32000;
  38                 break;
  39         case 44100:
  40                 fs = IEC958_AES3_CON_FS_44100;
  41                 break;
  42         case 48000:
  43                 fs = IEC958_AES3_CON_FS_48000;
  44                 break;
  45         case 88200:
  46                 fs = IEC958_AES3_CON_FS_88200;
  47                 break;
  48         case 96000:
  49                 fs = IEC958_AES3_CON_FS_96000;
  50                 break;
  51         case 176400:
  52                 fs = IEC958_AES3_CON_FS_176400;
  53                 break;
  54         case 192000:
  55                 fs = IEC958_AES3_CON_FS_192000;
  56                 break;
  57         default:
  58                 return -EINVAL;
  59         }
  60
  61         if (len > 4) {
  62                 switch (snd_pcm_format_width(runtime->format)) {
  63                 case 16:
  64                         ws = IEC958_AES4_CON_WORDLEN_20_16;
  65                         break;
  66                 case 18:
  67                         ws = IEC958_AES4_CON_WORDLEN_22_18;
  68                         break;
  69                 case 20:
  70                         ws = IEC958_AES4_CON_WORDLEN_20_16 |
  71                              IEC958_AES4_CON_MAX_WORDLEN_24;
  72                         break;
  73                 case 24:
  74                         ws = IEC958_AES4_CON_WORDLEN_24_20 |
  75                              IEC958_AES4_CON_MAX_WORDLEN_24;
  76                         break;
  77
  78                 default:
  79                         return -EINVAL;
  80                 }
  81         }
  82
  83         memset(cs, 0, len);
  84
  85         cs[0] = IEC958_AES0_CON_NOT_COPYRIGHT | IEC958_AES0_CON_EMPHASIS_NONE;
  86         cs[1] = IEC958_AES1_CON_GENERAL;
  87         cs[2] = IEC958_AES2_CON_SOURCE_UNSPEC | IEC958_AES2_CON_CHANNEL_UNSPEC;
  88         cs[3] = IEC958_AES3_CON_CLOCK_1000PPM | fs;
  89
  90         if (len > 4)
  91                 cs[4] = ws;
  92
  93         return len;
  94 }
  95 EXPORT_SYMBOL(snd_pcm_create_iec958_consumer);