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ALSA: firewire-lib: add no-header packet processing
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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>
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Takashi Sakamoto authored and Takashi Iwai committed Apr 5, 2017
1 parent ff0fb5a commit 3b196c3
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Showing 2 changed files with 81 additions and 5 deletions.
80 changes: 75 additions & 5 deletions sound/firewire/amdtp-stream.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@

/* isochronous header parameters */
#define ISO_DATA_LENGTH_SHIFT 16
#define TAG_NO_CIP_HEADER 0
#define TAG_CIP 1

/* common isochronous packet header parameters */
Expand Down Expand Up @@ -234,11 +235,15 @@ EXPORT_SYMBOL(amdtp_stream_set_parameters);
unsigned int amdtp_stream_get_max_payload(struct amdtp_stream *s)
{
unsigned int multiplier = 1;
unsigned int header_size = 0;

if (s->flags & CIP_JUMBO_PAYLOAD)
multiplier = 5;
if (!(s->flags & CIP_NO_HEADER))
header_size = 8;

return 8 + s->syt_interval * s->data_block_quadlets * 4 * multiplier;
return header_size +
s->syt_interval * s->data_block_quadlets * 4 * multiplier;
}
EXPORT_SYMBOL(amdtp_stream_get_max_payload);

Expand Down Expand Up @@ -380,7 +385,7 @@ static int queue_packet(struct amdtp_stream *s, unsigned int header_length,
goto end;

p.interrupt = IS_ALIGNED(s->packet_index + 1, INTERRUPT_INTERVAL);
p.tag = TAG_CIP;
p.tag = s->tag;
p.header_length = header_length;
if (payload_length > 0)
p.payload_length = payload_length;
Expand Down Expand Up @@ -457,6 +462,34 @@ static int handle_out_packet(struct amdtp_stream *s,
return 0;
}

static int handle_out_packet_without_header(struct amdtp_stream *s,
unsigned int payload_length, unsigned int cycle,
unsigned int index)
{
__be32 *buffer;
unsigned int syt;
unsigned int data_blocks;
unsigned int pcm_frames;
struct snd_pcm_substream *pcm;

buffer = s->buffer.packets[s->packet_index].buffer;
syt = calculate_syt(s, cycle);
data_blocks = calculate_data_blocks(s, syt);
pcm_frames = s->process_data_blocks(s, buffer, data_blocks, &syt);
s->data_block_counter = (s->data_block_counter + data_blocks) & 0xff;

payload_length = data_blocks * 4 * s->data_block_quadlets;
if (queue_out_packet(s, payload_length) < 0)
return -EIO;

pcm = ACCESS_ONCE(s->pcm);
if (pcm && pcm_frames > 0)
update_pcm_pointers(s, pcm, pcm_frames);

/* No need to return the number of handled data blocks. */
return 0;
}

static int handle_in_packet(struct amdtp_stream *s,
unsigned int payload_length, unsigned int cycle,
unsigned int index)
Expand Down Expand Up @@ -573,6 +606,30 @@ static int handle_in_packet(struct amdtp_stream *s,
return 0;
}

static int handle_in_packet_without_header(struct amdtp_stream *s,
unsigned int payload_quadlets, unsigned int cycle,
unsigned int index)
{
__be32 *buffer;
unsigned int data_blocks;
struct snd_pcm_substream *pcm;
unsigned int pcm_frames;

buffer = s->buffer.packets[s->packet_index].buffer;
data_blocks = payload_quadlets / s->data_block_quadlets;
pcm_frames = s->process_data_blocks(s, buffer, data_blocks, NULL);
s->data_block_counter = (s->data_block_counter + data_blocks) & 0xff;

if (queue_in_packet(s) < 0)
return -EIO;

pcm = ACCESS_ONCE(s->pcm);
if (pcm && pcm_frames > 0)
update_pcm_pointers(s, pcm, pcm_frames);

return 0;
}

/*
* In CYCLE_TIMER register of IEEE 1394, 7 bits are used to represent second. On
* the other hand, in DMA descriptors of 1394 OHCI, 3 bits are used to represent
Expand Down Expand Up @@ -616,7 +673,7 @@ static void out_stream_callback(struct fw_iso_context *context, u32 tstamp,

for (i = 0; i < packets; ++i) {
cycle = increment_cycle_count(cycle, 1);
if (handle_out_packet(s, 0, cycle, i) < 0) {
if (s->handle_packet(s, 0, cycle, i) < 0) {
s->packet_index = -1;
amdtp_stream_pcm_abort(s);
return;
Expand Down Expand Up @@ -663,7 +720,7 @@ static void in_stream_callback(struct fw_iso_context *context, u32 tstamp,
break;
}

if (handle_in_packet(s, payload_length, cycle, i) < 0)
if (s->handle_packet(s, payload_length, cycle, i) < 0)
break;
}

Expand Down Expand Up @@ -699,10 +756,18 @@ static void amdtp_stream_first_callback(struct fw_iso_context *context,
packets = header_length / IN_PACKET_HEADER_SIZE;
cycle = decrement_cycle_count(cycle, packets);
context->callback.sc = in_stream_callback;
if (s->flags & CIP_NO_HEADER)
s->handle_packet = handle_in_packet_without_header;
else
s->handle_packet = handle_in_packet;
} else {
packets = header_length / 4;
cycle = increment_cycle_count(cycle, QUEUE_LENGTH - packets);
context->callback.sc = out_stream_callback;
if (s->flags & CIP_NO_HEADER)
s->handle_packet = handle_out_packet_without_header;
else
s->handle_packet = handle_out_packet;
}

s->start_cycle = cycle;
Expand Down Expand Up @@ -782,6 +847,11 @@ int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)

amdtp_stream_update(s);

if (s->flags & CIP_NO_HEADER)
s->tag = TAG_NO_CIP_HEADER;
else
s->tag = TAG_CIP;

s->packet_index = 0;
do {
if (s->direction == AMDTP_IN_STREAM)
Expand All @@ -794,7 +864,7 @@ int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)

/* NOTE: TAG1 matches CIP. This just affects in stream. */
tag = FW_ISO_CONTEXT_MATCH_TAG1;
if (s->flags & CIP_EMPTY_WITH_TAG0)
if ((s->flags & CIP_EMPTY_WITH_TAG0) || (s->flags & CIP_NO_HEADER))
tag |= FW_ISO_CONTEXT_MATCH_TAG0;

s->callbacked = false;
Expand Down
6 changes: 6 additions & 0 deletions sound/firewire/amdtp-stream.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand All @@ -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,
};

/**
Expand Down Expand Up @@ -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;
Expand Down

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