xref: /openbmc/linux/sound/core/pcm_iec958.c (revision a06c488d)
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);
96