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authorRussell King <rmk+kernel@arm.linux.org.uk>2015-05-09 13:26:47 +0300
committerTakashi Iwai <tiwai@suse.de>2015-05-22 17:01:47 +0300
commit9203dd016a5d8ffb2eb6acdca60cd0b5dfe38c2b (patch)
treec827c3927ec50365e988f6c8934edfb54f279436 /sound/core/pcm_iec958.c
parent838d1631b766529213684f07dd71cdf2e92f0623 (diff)
downloadlinux-9203dd016a5d8ffb2eb6acdca60cd0b5dfe38c2b.tar.xz
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>
Diffstat (limited to 'sound/core/pcm_iec958.c')
-rw-r--r--sound/core/pcm_iec958.c95
1 files changed, 95 insertions, 0 deletions
diff --git a/sound/core/pcm_iec958.c b/sound/core/pcm_iec958.c
new file mode 100644
index 000000000000..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 <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);