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ALSA: pcm: add IEC958 channel status helper 

Add a helper to create the IEC958 channel status from an ALSA
snd_pcm_runtime structure, taking account of the sample rate and
sample size.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviwed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Russell King 2015-05-09 11:26:47 +01:00 committed by Takashi Iwai
parent 838d1631b7
commit 9203dd016a
4 changed files with 108 additions and 0 deletions
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9
include/sound/pcm_iec958.h Normal file
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@ -0,0 +1,9 @@
#ifndef __SOUND_PCM_IEC958_H
#define __SOUND_PCM_IEC958_H
#include <linux/types.h>
int snd_pcm_create_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
size_t len);
#endif

3
sound/core/Kconfig
View File

@ -9,6 +9,9 @@ config SND_PCM
config SND_PCM_ELD
bool
config SND_PCM_IEC958
bool
config SND_DMAENGINE_PCM
tristate

1
sound/core/Makefile
View File

@ -14,6 +14,7 @@ snd-pcm-y := pcm.o pcm_native.o pcm_lib.o pcm_timer.o pcm_misc.o \
pcm_memory.o memalloc.o
snd-pcm-$(CONFIG_SND_DMA_SGBUF) += sgbuf.o
snd-pcm-$(CONFIG_SND_PCM_ELD) += pcm_drm_eld.o
snd-pcm-$(CONFIG_SND_PCM_IEC958) += pcm_iec958.o
# for trace-points
CFLAGS_pcm_lib.o := -I$(src)

95
sound/core/pcm_iec958.c Normal file
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@ -0,0 +1,95 @@
/*
* PCM DRM helpers
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/export.h>
#include <linux/types.h>
#include <sound/asoundef.h>
#include <sound/pcm.h>
#include <sound/pcm_iec958.h>
/**
* snd_pcm_create_iec958_consumer - create consumer format IEC958 channel status
* @runtime: pcm runtime structure with ->rate filled in
* @cs: channel status buffer, at least four bytes
* @len: length of channel status buffer
*
* Create the consumer format channel status data in @cs of maximum size
* @len corresponding to the parameters of the PCM runtime @runtime.
*
* Drivers may wish to tweak the contents of the buffer after creation.
*
* Returns: length of buffer, or negative error code if something failed.
*/
int snd_pcm_create_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
size_t len)
{
unsigned int fs, ws;
if (len < 4)
return -EINVAL;
switch (runtime->rate) {
case 32000:
fs = IEC958_AES3_CON_FS_32000;
break;
case 44100:
fs = IEC958_AES3_CON_FS_44100;
break;
case 48000:
fs = IEC958_AES3_CON_FS_48000;
break;
case 88200:
fs = IEC958_AES3_CON_FS_88200;
break;
case 96000:
fs = IEC958_AES3_CON_FS_96000;
break;
case 176400:
fs = IEC958_AES3_CON_FS_176400;
break;
case 192000:
fs = IEC958_AES3_CON_FS_192000;
break;
default:
return -EINVAL;
}
if (len > 4) {
switch (snd_pcm_format_width(runtime->format)) {
case 16:
ws = IEC958_AES4_CON_WORDLEN_20_16;
break;
case 18:
ws = IEC958_AES4_CON_WORDLEN_22_18;
break;
case 20:
ws = IEC958_AES4_CON_WORDLEN_20_16 |
IEC958_AES4_CON_MAX_WORDLEN_24;
break;
case 24:
ws = IEC958_AES4_CON_WORDLEN_24_20 |
IEC958_AES4_CON_MAX_WORDLEN_24;
break;
default:
return -EINVAL;
}
}
memset(cs, 0, len);
cs[0] = IEC958_AES0_CON_NOT_COPYRIGHT | IEC958_AES0_CON_EMPHASIS_NONE;
cs[1] = IEC958_AES1_CON_GENERAL;
cs[2] = IEC958_AES2_CON_SOURCE_UNSPEC | IEC958_AES2_CON_CHANNEL_UNSPEC;
cs[3] = IEC958_AES3_CON_CLOCK_1000PPM | fs;
if (len > 4)
cs[4] = ws;
return len;
}
EXPORT_SYMBOL(snd_pcm_create_iec958_consumer);