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linux/sound/firewire/amdtp-stream.h
Takashi Sakamoto dec63cc8b6 ALSA: firewire-lib: handle IT/IR contexts in each software interrupt context 
In clause 6.3 of IEC 61883-6:2000, there's an explanation about processing
of presentation timestamp. In the clause, we can see "If a function block
receives a CIP, processes it and subsequently re-transmits it, then the
SYT of the outgoing CIP shall be the sum of the incoming SYT and the
processing delay." ALSA firewire stack has an implementation to partly
satisfy this specification. Developers assumed the stack to perform as an
Audio function block[1].

Following to the assumption, current implementation of ALSA firewire stack
use one software interrupt context to handle both of in/out packets. In
most case, this is processed in 1394 OHCI IR context independently of the
opposite context. Thus, this implementation uses longer CPU time in the
software interrupt context. This is not better for whole system.

Against the assumption, I confirmed that each ASIC for IEC 61883-1/6
doesn't necessarily expect it to the stack. Thus, current implementation
of ALSA firewire stack includes over-engineering.

This commit purges the implementation. As a result, packets of one
direction are handled in one software interrupt context and spends
minimum CPU time.

[1] [alsa-devel] [PATCH 0/8] [RFC] new driver for Echo Audio's Fireworks based devices
http://mailman.alsa-project.org/pipermail/alsa-devel/2013-June/062660.html

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2016-05-10 17:03:59 +02:00

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#ifndef SOUND_FIREWIRE_AMDTP_H_INCLUDED
#define SOUND_FIREWIRE_AMDTP_H_INCLUDED
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <sound/asound.h>
#include "packets-buffer.h"
/**
* enum cip_flags - describes details of the streaming protocol
* @CIP_NONBLOCKING: In non-blocking mode, each packet contains
* sample_rate/8000 samples, with rounding up or down to adjust
* for clock skew and left-over fractional samples. This should
* be used if supported by the device.
* @CIP_BLOCKING: In blocking mode, each packet contains either zero or
* SYT_INTERVAL samples, with these two types alternating so that
* the overall sample rate comes out right.
* @CIP_EMPTY_WITH_TAG0: Only for in-stream. Empty in-packets have TAG0.
* @CIP_DBC_IS_END_EVENT: Only for in-stream. The value of dbc in an in-packet
* corresponds to the end of event in the packet. Out of IEC 61883.
* @CIP_WRONG_DBS: Only for in-stream. The value of dbs is wrong in in-packets.
* The value of data_block_quadlets is used instead of reported value.
* @CIP_SKIP_DBC_ZERO_CHECK: Only for in-stream. Packets with zero in dbc is
* skipped for detecting discontinuity.
* @CIP_SKIP_INIT_DBC_CHECK: Only for in-stream. The value of dbc in first
* packet is not continuous from an initial value.
* @CIP_EMPTY_HAS_WRONG_DBC: Only for in-stream. The value of dbc in empty
* packet is wrong but the others are correct.
* @CIP_JUMBO_PAYLOAD: Only for in-stream. The number of data blocks in an
* packet is larger than IEC 61883-6 defines. Current implementation
* allows 5 times as large as IEC 61883-6 defines.
*/
enum cip_flags {
CIP_NONBLOCKING = 0x00,
CIP_BLOCKING = 0x01,
CIP_EMPTY_WITH_TAG0 = 0x02,
CIP_DBC_IS_END_EVENT = 0x04,
CIP_WRONG_DBS = 0x08,
CIP_SKIP_DBC_ZERO_CHECK = 0x10,
CIP_SKIP_INIT_DBC_CHECK = 0x20,
CIP_EMPTY_HAS_WRONG_DBC = 0x40,
CIP_JUMBO_PAYLOAD = 0x80,
};
/**
* enum cip_sfc - supported Sampling Frequency Codes (SFCs)
* @CIP_SFC_32000: 32,000 data blocks
* @CIP_SFC_44100: 44,100 data blocks
* @CIP_SFC_48000: 48,000 data blocks
* @CIP_SFC_88200: 88,200 data blocks
* @CIP_SFC_96000: 96,000 data blocks
* @CIP_SFC_176400: 176,400 data blocks
* @CIP_SFC_192000: 192,000 data blocks
* @CIP_SFC_COUNT: the number of supported SFCs
*
* These values are used to show nominal Sampling Frequency Code in
* Format Dependent Field (FDF) of AMDTP packet header. In IEC 61883-6:2002,
* this code means the number of events per second. Actually the code
* represents the number of data blocks transferred per second in an AMDTP
* stream.
*
* In IEC 61883-6:2005, some extensions were added to support more types of
* data such as 'One Bit LInear Audio', therefore the meaning of SFC became
* different depending on the types.
*
* Currently our implementation is compatible with IEC 61883-6:2002.
*/
enum cip_sfc {
CIP_SFC_32000 = 0,
CIP_SFC_44100 = 1,
CIP_SFC_48000 = 2,
CIP_SFC_88200 = 3,
CIP_SFC_96000 = 4,
CIP_SFC_176400 = 5,
CIP_SFC_192000 = 6,
CIP_SFC_COUNT
};
struct fw_unit;
struct fw_iso_context;
struct snd_pcm_substream;
struct snd_pcm_runtime;
enum amdtp_stream_direction {
AMDTP_OUT_STREAM = 0,
AMDTP_IN_STREAM
};
struct amdtp_stream;
typedef unsigned int (*amdtp_stream_process_data_blocks_t)(
struct amdtp_stream *s,
__be32 *buffer,
unsigned int data_blocks,
unsigned int *syt);
struct amdtp_stream {
struct fw_unit *unit;
enum cip_flags flags;
enum amdtp_stream_direction direction;
struct mutex mutex;
/* For packet processing. */
struct fw_iso_context *context;
struct iso_packets_buffer buffer;
int packet_index;
/* For CIP headers. */
unsigned int source_node_id_field;
unsigned int data_block_quadlets;
unsigned int data_block_counter;
unsigned int fmt;
unsigned int fdf;
/* quirk: fixed interval of dbc between previos/current packets. */
unsigned int tx_dbc_interval;
/* quirk: indicate the value of dbc field in a first packet. */
unsigned int tx_first_dbc;
/* Internal flags. */
enum cip_sfc sfc;
unsigned int syt_interval;
unsigned int transfer_delay;
unsigned int data_block_state;
unsigned int last_syt_offset;
unsigned int syt_offset_state;
/* For a PCM substream processing. */
struct snd_pcm_substream *pcm;
struct tasklet_struct period_tasklet;
unsigned int pcm_buffer_pointer;
unsigned int pcm_period_pointer;
bool pointer_flush;
/* To wait for first packet. */
bool callbacked;
wait_queue_head_t callback_wait;
/* For backends to process data blocks. */
void *protocol;
amdtp_stream_process_data_blocks_t process_data_blocks;
};
int amdtp_stream_init(struct amdtp_stream *s, struct fw_unit *unit,
enum amdtp_stream_direction dir, enum cip_flags flags,
unsigned int fmt,
amdtp_stream_process_data_blocks_t process_data_blocks,
unsigned int protocol_size);
void amdtp_stream_destroy(struct amdtp_stream *s);
int amdtp_stream_set_parameters(struct amdtp_stream *s, unsigned int rate,
unsigned int data_block_quadlets);
unsigned int amdtp_stream_get_max_payload(struct amdtp_stream *s);
int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed);
void amdtp_stream_update(struct amdtp_stream *s);
void amdtp_stream_stop(struct amdtp_stream *s);
int amdtp_stream_add_pcm_hw_constraints(struct amdtp_stream *s,
struct snd_pcm_runtime *runtime);
void amdtp_stream_pcm_prepare(struct amdtp_stream *s);
unsigned long amdtp_stream_pcm_pointer(struct amdtp_stream *s);
void amdtp_stream_pcm_abort(struct amdtp_stream *s);
extern const unsigned int amdtp_syt_intervals[CIP_SFC_COUNT];
extern const unsigned int amdtp_rate_table[CIP_SFC_COUNT];
/**
* amdtp_stream_running - check stream is running or not
* @s: the AMDTP stream
*
* If this function returns true, the stream is running.
*/
static inline bool amdtp_stream_running(struct amdtp_stream *s)
{
return !IS_ERR(s->context);
}
/**
* amdtp_streaming_error - check for streaming error
* @s: the AMDTP stream
*
* If this function returns true, the stream's packet queue has stopped due to
* an asynchronous error.
*/
static inline bool amdtp_streaming_error(struct amdtp_stream *s)
{
return s->packet_index < 0;
}
/**
* amdtp_stream_pcm_running - check PCM substream is running or not
* @s: the AMDTP stream
*
* If this function returns true, PCM substream in the AMDTP stream is running.
*/
static inline bool amdtp_stream_pcm_running(struct amdtp_stream *s)
{
return !!s->pcm;
}
/**
* amdtp_stream_pcm_trigger - start/stop playback from a PCM device
* @s: the AMDTP stream
* @pcm: the PCM device to be started, or %NULL to stop the current device
*
* Call this function on a running isochronous stream to enable the actual
* transmission of PCM data. This function should be called from the PCM
* device's .trigger callback.
*/
static inline void amdtp_stream_pcm_trigger(struct amdtp_stream *s,
struct snd_pcm_substream *pcm)
{
ACCESS_ONCE(s->pcm) = pcm;
}
static inline bool cip_sfc_is_base_44100(enum cip_sfc sfc)
{
return sfc & 1;
}
/**
* amdtp_stream_wait_callback - sleep till callbacked or timeout
* @s: the AMDTP stream
* @timeout: msec till timeout
*
* If this function return false, the AMDTP stream should be stopped.
*/
static inline bool amdtp_stream_wait_callback(struct amdtp_stream *s,
unsigned int timeout)
{
return wait_event_timeout(s->callback_wait,
s->callbacked == true,
msecs_to_jiffies(timeout)) > 0;
}
#endif
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