[PATCH RFC 09/11] sound/core: add IEC958 channel status helper

[Russell King <rmk+kernel@arm.linux.org.uk>]

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

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 include/sound/pcm_iec958.h |  9 ++++++
 sound/core/Kconfig         |  3 ++
 sound/core/Makefile        |  2 ++
 sound/core/pcm_iec958.c    | 70 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 84 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 000000000000..0eed397aca8e
--- /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 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..70ea06712ec2 100644
--- a/sound/core/Makefile
+++ b/sound/core/Makefile
@@ -14,10 +14,12 @@ 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) += snd-pcm-iec958.o
 
 # for trace-points
 CFLAGS_pcm_lib.o := -I$(src)
 
+snd-pcm-iec958-objs := pcm_iec958.o
 snd-pcm-dmaengine-objs := pcm_dmaengine.o
 
 snd-rawmidi-objs  := rawmidi.o
diff --git a/sound/core/pcm_iec958.c b/sound/core/pcm_iec958.c
new file mode 100644
index 000000000000..e1ff88a17dde
--- /dev/null
+++ b/sound/core/pcm_iec958.c
@@ -0,0 +1,70 @@
+/*
+ *  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 as published by
+ *   the Free Software Foundation; either version 2 of the License.
+ */
+#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;
+
+	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;
+	}
+
+	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;
+
+	return len;
+}
+EXPORT_SYMBOL(snd_pcm_create_iec958_consumer);
-- 
1.8.3.1