ALSA: firewire-lib: add no-header packet processing

As long as investigating Fireface 400, IEC 61883-1/6 is not applied to
its packet streaming protocol. Remarks of the specific protocol are:
 * Each packet doesn't include CIP headers.
 * 64,0 and 128,0 kHz are supported.
 * The device doesn't necessarily transmit 8,000 packets per second.
 * 0, 1, 2, 3 are used as tag for rx isochronous packets, however 0 is
   used for tx isochronous packets.

On the other hand, there's a common feature. The number of data blocks
transferred in a second is the same as sampling transmission frequency.
Current ALSA IEC 61883-1/6 engine already has a method to calculate it and
this driver can utilize it for rx packets, as well as tx packets.

This commit adds support for the transferring protocol. CIP_NO_HEADERS
flag is newly added. When this flag is set:
 * Both of 0 (without CIP header) and 1 (with CIP header) are used as tag
   to handle incoming isochronous packet.
 * 0 (without CIP header) is used as tag to transfer outgoing isochronous
   packet.
 * Skip CIP header evaluation.
 * Use unique way to calculate the quadlets of isochronous packet payload.

In ALSA PCM interface, 128.0 kHz is not supported, and the ALSA
IEC 61883-1/6 engine doesn't support 64.0 kHz. These modes are dropped.

The sequence of rx packet has a remarkable quirk about tag. This will be
described in later commits.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/amdtp-stream.h

@@ -31,6 +31,7 @@
  *	allows 5 times as large as IEC 61883-6 defines.
  * @CIP_HEADER_WITHOUT_EOH: Only for in-stream. CIP Header doesn't include
  *	valid EOH.
+ * @CIP_NO_HEADERS: a lack of headers in packets
  */
 enum cip_flags {
 	CIP_NONBLOCKING		= 0x00,
@@ -42,6 +43,7 @@ enum cip_flags {
 	CIP_EMPTY_HAS_WRONG_DBC	= 0x20,
 	CIP_JUMBO_PAYLOAD	= 0x40,
 	CIP_HEADER_WITHOUT_EOH	= 0x80,
+	CIP_NO_HEADER		= 0x100,
 };
 
 /**
@@ -104,6 +106,10 @@ struct amdtp_stream {
 	struct fw_iso_context *context;
 	struct iso_packets_buffer buffer;
 	int packet_index;
+	int tag;
+	int (*handle_packet)(struct amdtp_stream *s,
+			unsigned int payload_quadlets, unsigned int cycle,
+			unsigned int index);
 
 	/* For CIP headers. */
 	unsigned int source_node_id_field;