sound/core/pcm_iec958.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  PCM DRM helpers
   4  */
   5 #include <linux/export.h>
   6 #include <linux/types.h>
   7 #include <sound/asoundef.h>
   8 #include <sound/pcm.h>
   9 #include <sound/pcm_params.h>
  10 #include <sound/pcm_iec958.h>
  11
  12 static int create_iec958_consumer(uint rate, uint sample_width,
  13                                   u8 *cs, size_t len)
  14 {
  15         unsigned int fs, ws;
  16
  17         if (len < 4)
  18                 return -EINVAL;
  19
  20         switch (rate) {
  21         case 32000:
  22                 fs = IEC958_AES3_CON_FS_32000;
  23                 break;
  24         case 44100:
  25                 fs = IEC958_AES3_CON_FS_44100;
  26                 break;
  27         case 48000:
  28                 fs = IEC958_AES3_CON_FS_48000;
  29                 break;
  30         case 88200:
  31                 fs = IEC958_AES3_CON_FS_88200;
  32                 break;
  33         case 96000:
  34                 fs = IEC958_AES3_CON_FS_96000;
  35                 break;
  36         case 176400:
  37                 fs = IEC958_AES3_CON_FS_176400;
  38                 break;
  39         case 192000:
  40                 fs = IEC958_AES3_CON_FS_192000;
  41                 break;
  42         default:
  43                 return -EINVAL;
  44         }
  45
  46         if (len > 4) {
  47                 switch (sample_width) {
  48                 case 16:
  49                         ws = IEC958_AES4_CON_WORDLEN_20_16;
  50                         break;
  51                 case 18:
  52                         ws = IEC958_AES4_CON_WORDLEN_22_18;
  53                         break;
  54                 case 20:
  55                         ws = IEC958_AES4_CON_WORDLEN_20_16 |
  56                              IEC958_AES4_CON_MAX_WORDLEN_24;
  57                         break;
  58                 case 24:
  59                 case 32: /* Assume 24-bit width for 32-bit samples. */
  60                         ws = IEC958_AES4_CON_WORDLEN_24_20 |
  61                              IEC958_AES4_CON_MAX_WORDLEN_24;
  62                         break;
  63
  64                 default:
  65                         return -EINVAL;
  66                 }
  67         }
  68
  69         memset(cs, 0, len);
  70
  71         cs[0] = IEC958_AES0_CON_NOT_COPYRIGHT | IEC958_AES0_CON_EMPHASIS_NONE;
  72         cs[1] = IEC958_AES1_CON_GENERAL;
  73         cs[2] = IEC958_AES2_CON_SOURCE_UNSPEC | IEC958_AES2_CON_CHANNEL_UNSPEC;
  74         cs[3] = IEC958_AES3_CON_CLOCK_1000PPM | fs;
  75
  76         if (len > 4)
  77                 cs[4] = ws;
  78
  79         return len;
  80 }
  81
  82 /**
  83  * snd_pcm_create_iec958_consumer - create consumer format IEC958 channel status
  84  * @runtime: pcm runtime structure with ->rate filled in
  85  * @cs: channel status buffer, at least four bytes
  86  * @len: length of channel status buffer
  87  *
  88  * Create the consumer format channel status data in @cs of maximum size
  89  * @len corresponding to the parameters of the PCM runtime @runtime.
  90  *
  91  * Drivers may wish to tweak the contents of the buffer after creation.
  92  *
  93  * Returns: length of buffer, or negative error code if something failed.
  94  */
  95 int snd_pcm_create_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
  96         size_t len)
  97 {
  98         return create_iec958_consumer(runtime->rate,
  99                                       snd_pcm_format_width(runtime->format),
 100                                       cs, len);
 101 }
 102 EXPORT_SYMBOL(snd_pcm_create_iec958_consumer);
 103
 104 /**
 105  * snd_pcm_create_iec958_consumer_hw_params - create IEC958 channel status
 106  * @hw_params: the hw_params instance for extracting rate and sample format
 107  * @cs: channel status buffer, at least four bytes
 108  * @len: length of channel status buffer
 109  *
 110  * Create the consumer format channel status data in @cs of maximum size
 111  * @len corresponding to the parameters of the PCM runtime @runtime.
 112  *
 113  * Drivers may wish to tweak the contents of the buffer after creation.
 114  *
 115  * Returns: length of buffer, or negative error code if something failed.
 116  */
 117 int snd_pcm_create_iec958_consumer_hw_params(struct snd_pcm_hw_params *params,
 118                                              u8 *cs, size_t len)
 119 {
 120         return create_iec958_consumer(params_rate(params), params_width(params),
 121                                       cs, len);
 122 }
 123 EXPORT_SYMBOL(snd_pcm_create_iec958_consumer_hw_params);