[PATCH 11/13] sound/core: add IEC958 channel status helper

[Mark Brown]

On Sat, May 09, 2015 at 11:26:47AM +0100, Russell King wrote:
> 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.

This also looks good to me from an interface point of view:

Reviwed-by: Mark Brown 
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[PATCH 11/13] sound/core: add IEC958 channel status helper

[Russell King]

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 
---
 include/sound/pcm_iec958.h |  9 +
 sound/core/Kconfig |  3 ++
 sound/core/Makefile|  1 +
 sound/core/pcm_iec958.c| 95 ++
 4 files changed, 108 insertions(+)
 create mode 100644 include/sound/pcm_iec958.h
 create mode 100644 sound/core/pcm_iec958.c

diff --git a/include/sound/pcm_iec958.h b/include/sound/pcm_iec958.h
new file mode 100644
index ..0eed397aca8e
--- /dev/null
+++ b/include/sound/pcm_iec958.h
@@ -0,0 +1,9 @@
+#ifndef __SOUND_PCM_IEC958_H
+#define __SOUND_PCM_IEC958_H
+
+#include 
+
+int snd_pcm_create_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
+   size_t len);
+
+#endif
diff --git a/sound/core/Kconfig b/sound/core/Kconfig
index b534c8a6046b..1507469425ec 100644
--- a/sound/core/Kconfig
+++ b/sound/core/Kconfig
@@ -9,6 +9,9 @@ config SND_PCM
 config SND_PCM_ELD
bool

+config SND_PCM_IEC958
+   bool
+
 config SND_DMAENGINE_PCM
tristate

diff --git a/sound/core/Makefile b/sound/core/Makefile
index 591b49157b4d..2b925fcc95ea 100644
--- a/sound/core/Makefile
+++ b/sound/core/Makefile
@@ -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)
diff --git a/sound/core/pcm_iec958.c b/sound/core/pcm_iec958.c
new file mode 100644
index ..36b2d7aca1bd
--- /dev/null
+++ b/sound/core/pcm_iec958.c
@@ -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 
+#include 
+#include 
+#include 
+#include 
+
+/**
+ * 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);
-- 
1.8.3.1