1 files changed, 84 insertions, 0 deletions
diff --git a/drivers/ieee1394/amdtp.h b/drivers/ieee1394/amdtp.h
new file mode 100644
index 00000000000..531f28e3ab5
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+++ b/drivers/ieee1394/amdtp.h
@@ -0,0 +1,84 @@
+/* -*- c-basic-offset: 8 -*- */
+
+#ifndef __AMDTP_H
+#define __AMDTP_H
+
+#include <asm/types.h>
+#include "ieee1394-ioctl.h"
+
+/* The userspace interface for the Audio & Music Data Transmission
+ * Protocol driver is really simple. First, open /dev/amdtp, use the
+ * ioctl to configure format, rate, dimension and either plug or
+ * channel, then start writing samples.
+ *
+ * The formats supported by the driver are listed below.
+ * AMDTP_FORMAT_RAW corresponds to the AM824 raw format, which can
+ * carry any number of channels, so use this if you're streaming
+ * multichannel audio.  The AMDTP_FORMAT_IEC958_PCM corresponds to the
+ * AM824 IEC958 encapsulation without the IEC958 data bit set, using
+ * AMDTP_FORMAT_IEC958_AC3 will transmit the samples with the data bit
+ * set, suitable for transmitting compressed AC-3 audio.
+ *
+ * The rate field specifies the transmission rate; supported values
+ * are 32000, 44100, 48000, 88200, 96000, 176400 and 192000.
+ *
+ * The dimension field specifies the dimension of the signal, that is,
+ * the number of audio channels.  Only AMDTP_FORMAT_RAW supports
+ * settings greater than 2.
+ *
+ * The mode field specifies which transmission mode to use. The AMDTP
+ * specifies two different transmission modes: blocking and
+ * non-blocking.  The blocking transmission mode always send a fixed
+ * number of samples, typically 8, 16 or 32.  To exactly match the
+ * transmission rate, the driver alternates between sending empty and
+ * non-empty packets.  In non-blocking mode, the driver transmits as
+ * small packets as possible.  For example, for a transmission rate of
+ * 44100Hz, the driver should send 5 41/80 samples in every cycle, but
+ * this is not possible so instead the driver alternates between
+ * sending 5 and 6 samples.
+ *
+ * The last thing to specify is either the isochronous channel to use
+ * or the output plug to connect to.  If you know what channel the
+ * destination device will listen on, you can specify the channel
+ * directly and use the AMDTP_IOC_CHANNEL ioctl.  However, if the
+ * destination device chooses the channel and uses the IEC61883-1 plug
+ * mechanism, you can specify an output plug to connect to.  The
+ * driver will pick up the channel number from the plug once the
+ * destination device locks the output plug control register.  In this
+ * case set the plug field and use the AMDTP_IOC_PLUG ioctl.
+ *
+ * Having configured the interface, the driver now accepts writes of
+ * regular 16 bit signed little endian samples, with the channels
+ * interleaved.  For example, 4 channels would look like:
+ *
+ *   | sample 0                                      | sample 1    ...
+ *   | ch. 0     | ch. 1     | ch. 2     | ch. 3     | ch. 0     | ...
+ *   | lsb | msb | lsb | msb | lsb | msb | lsb | msb | lsb | msb | ...
+ *
+ */
+
+enum {
+	AMDTP_FORMAT_RAW,
+	AMDTP_FORMAT_IEC958_PCM,
+	AMDTP_FORMAT_IEC958_AC3
+};
+
+enum {
+	AMDTP_MODE_BLOCKING,
+	AMDTP_MODE_NON_BLOCKING,
+};
+
+enum {
+	AMDTP_INPUT_LE16,
+	AMDTP_INPUT_BE16,
+};
+
+struct amdtp_ioctl {
+	__u32 format;
+	__u32 rate;
+	__u32 dimension;
+	__u32 mode;
+	union { __u32 channel; __u32 plug; } u;
+};
+
+#endif /* __AMDTP_H */