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>

diff --git a/include/sound/pcm_iec958.h b/include/sound/pcm_iec958.h
new file mode 100644 (file)
index 0000000..0eed397
--- /dev/null
+++ b/include/sound/pcm_iec958.h
@@ -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

diff --git a/sound/core/Kconfig b/sound/core/Kconfig
index b534c8a6046b1f83e6a86ce3f8366932fe264b1f..1507469425ece3a6ce7cec21264bc4231e427643 100644 (file)
--- 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 591b49157b4d49847d572e59f44ad56dbeb8fbe8..2b925fcc95eaf1bbd38e9957f88c7d8c32d26bbe 100644 (file)
--- 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 (file)
index 0000000..36b2d7a
--- /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 <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);