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
 12static 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 */
 95int 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}
102EXPORT_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 */
117int 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}
123EXPORT_SYMBOL(snd_pcm_create_iec958_consumer_hw_params);