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Commit 163ae6f3 authored by Takashi Sakamoto's avatar Takashi Sakamoto Committed by Takashi Iwai
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ALSA: firewire-digi00x: add data block processing layer 



Digi 002/003 family uses its own format for data blocks. The format is
quite similar to AM824 in IEC 61883-6, while there're some differences:

 * The Valid Bit Length (VBL) code is always 0x40 in Multi-bit Linear Audio
   (MBLA) data channel.
 * The first data channel includes MIDI messages, against IEC 61883-6
   recommendation.
 * The Counter field is always zero in MIDI conformant data channel.
 * Sequence multiplexing in IEC 61883-6 is not applied to the MIDI
   conformant data channel.
 * PCM samples are scrambled in received AMDTP packets. We call the way
   as Double-Oh-Three (DOT). The algorithm was discovered by
   Robin Gareus and Damien Zammit in 2012.

This commit adds data processing layer to satisfy these differences.

There's a quirk about transmission mode for received packets. When this
driver applies non-blocking mode to outgoing packets with isochronous
channel 2 or more, after 15 to 20 seconds since playbacking, any PCM
samples causes noisy sound on the device. With isochronous channel 0 or 1,
this doesn't occur. As long as I investigated, this quirk is not observed
when applying blocking mode to the received packets.

This driver applies blocking mode to outgoing packets, while non-blocking
mode to incoming packgets.

Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 9edf723f

sound/firewire/digi00x/Makefile

+1 −1
Original line number Diff line number Diff line 
snd-firewire-digi00x-objs := digi00x.o

snd-firewire-digi00x-objs := amdtp-dot.o digi00x.o

obj-$(CONFIG_SND_FIREWIRE_DIGI00X) += snd-firewire-digi00x.o

sound/firewire/digi00x/amdtp-dot.c

0 → 100644
+330 −0
Original line number Diff line number Diff line 
/*

 * amdtp-dot.c - a part of driver for Digidesign Digi 002/003 family

 *

 * Copyright (c) 2014-2015 Takashi Sakamoto

 * Copyright (C) 2012 Robin Gareus <robin@gareus.org>

 * Copyright (C) 2012 Damien Zammit <damien@zamaudio.com>

 *

 * Licensed under the terms of the GNU General Public License, version 2.

 */



#include <sound/pcm.h>

#include "digi00x.h"



#define CIP_FMT_AM		0x10



/* 'Clock-based rate control mode' is just supported. */

#define AMDTP_FDF_AM824		0x00



/*

 * The double-oh-three algorithm was discovered by Robin Gareus and Damien

 * Zammit in 2012, with reverse-engineering for Digi 003 Rack.

 */

struct dot_state {

	__u8 carry;

	__u8 idx;

	unsigned int off;

};



struct amdtp_dot {

	unsigned int pcm_channels;

	struct dot_state state;



	unsigned int midi_ports;



	void (*transfer_samples)(struct amdtp_stream *s,

				 struct snd_pcm_substream *pcm,

				 __be32 *buffer, unsigned int frames);

};



/*

 * double-oh-three look up table

 *

 * @param idx index byte (audio-sample data) 0x00..0xff

 * @param off channel offset shift

 * @return salt to XOR with given data

 */

#define BYTE_PER_SAMPLE (4)

#define MAGIC_DOT_BYTE (2)

#define MAGIC_BYTE_OFF(x) (((x) * BYTE_PER_SAMPLE) + MAGIC_DOT_BYTE)

static const __u8 dot_scrt(const __u8 idx, const unsigned int off)

{

	/*

	 * the length of the added pattern only depends on the lower nibble

	 * of the last non-zero data

	 */

	static const __u8 len[16] = {0, 1, 3, 5, 7, 9, 11, 13, 14,

				     12, 10, 8, 6, 4, 2, 0};



	/*

	 * the lower nibble of the salt. Interleaved sequence.

	 * this is walked backwards according to len[]

	 */

	static const __u8 nib[15] = {0x8, 0x7, 0x9, 0x6, 0xa, 0x5, 0xb, 0x4,

				     0xc, 0x3, 0xd, 0x2, 0xe, 0x1, 0xf};



	/* circular list for the salt's hi nibble. */

	static const __u8 hir[15] = {0x0, 0x6, 0xf, 0x8, 0x7, 0x5, 0x3, 0x4,

				     0xc, 0xd, 0xe, 0x1, 0x2, 0xb, 0xa};



	/*

	 * start offset for upper nibble mapping.

	 * note: 9 is /special/. In the case where the high nibble == 0x9,

	 * hir[] is not used and - coincidentally - the salt's hi nibble is

	 * 0x09 regardless of the offset.

	 */

	static const __u8 hio[16] = {0, 11, 12, 6, 7, 5, 1, 4,

				     3, 0x00, 14, 13, 8, 9, 10, 2};



	const __u8 ln = idx & 0xf;

	const __u8 hn = (idx >> 4) & 0xf;

	const __u8 hr = (hn == 0x9) ? 0x9 : hir[(hio[hn] + off) % 15];



	if (len[ln] < off)

		return 0x00;



	return ((nib[14 + off - len[ln]]) | (hr << 4));

}



static void dot_encode_step(struct dot_state *state, __be32 *const buffer)

{

	__u8 * const data = (__u8 *) buffer;



	if (data[MAGIC_DOT_BYTE] != 0x00) {

		state->off = 0;

		state->idx = data[MAGIC_DOT_BYTE] ^ state->carry;

	}

	data[MAGIC_DOT_BYTE] ^= state->carry;

	state->carry = dot_scrt(state->idx, ++(state->off));

}



int amdtp_dot_set_parameters(struct amdtp_stream *s, unsigned int rate,

			     unsigned int pcm_channels, unsigned int midi_ports)

{

	struct amdtp_dot *p = s->protocol;

	int err;



	if (amdtp_stream_running(s))

		return -EBUSY;



	/*

	 * A first data channel is for MIDI conformant data channel, the rest is

	 * Multi Bit Linear Audio data channel.

	 */

	err = amdtp_stream_set_parameters(s, rate, pcm_channels + 1);

	if (err < 0)

		return err;



	s->fdf = AMDTP_FDF_AM824 | s->sfc;



	p->pcm_channels = pcm_channels;

	p->midi_ports = midi_ports;



	return 0;

}



static void write_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,

			  __be32 *buffer, unsigned int frames)

{

	struct amdtp_dot *p = s->protocol;

	struct snd_pcm_runtime *runtime = pcm->runtime;

	unsigned int channels, remaining_frames, i, c;

	const u32 *src;



	channels = p->pcm_channels;

	src = (void *)runtime->dma_area +

			frames_to_bytes(runtime, s->pcm_buffer_pointer);

	remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;



	buffer++;

	for (i = 0; i < frames; ++i) {

		for (c = 0; c < channels; ++c) {

			buffer[c] = cpu_to_be32((*src >> 8) | 0x40000000);

			dot_encode_step(&p->state, &buffer[c]);

			src++;

		}

		buffer += s->data_block_quadlets;

		if (--remaining_frames == 0)

			src = (void *)runtime->dma_area;

	}

}



static void write_pcm_s16(struct amdtp_stream *s, struct snd_pcm_substream *pcm,

			  __be32 *buffer, unsigned int frames)

{

	struct amdtp_dot *p = s->protocol;

	struct snd_pcm_runtime *runtime = pcm->runtime;

	unsigned int channels, remaining_frames, i, c;

	const u16 *src;



	channels = p->pcm_channels;

	src = (void *)runtime->dma_area +

			frames_to_bytes(runtime, s->pcm_buffer_pointer);

	remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;



	buffer++;

	for (i = 0; i < frames; ++i) {

		for (c = 0; c < channels; ++c) {

			buffer[c] = cpu_to_be32((*src << 8) | 0x40000000);

			dot_encode_step(&p->state, &buffer[c]);

			src++;

		}

		buffer += s->data_block_quadlets;

		if (--remaining_frames == 0)

			src = (void *)runtime->dma_area;

	}

}



static void read_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,

			 __be32 *buffer, unsigned int frames)

{

	struct amdtp_dot *p = s->protocol;

	struct snd_pcm_runtime *runtime = pcm->runtime;

	unsigned int channels, remaining_frames, i, c;

	u32 *dst;



	channels = p->pcm_channels;

	dst  = (void *)runtime->dma_area +

			frames_to_bytes(runtime, s->pcm_buffer_pointer);

	remaining_frames = runtime->buffer_size - s->pcm_buffer_pointer;



	buffer++;

	for (i = 0; i < frames; ++i) {

		for (c = 0; c < channels; ++c) {

			*dst = be32_to_cpu(buffer[c]) << 8;

			dst++;

		}

		buffer += s->data_block_quadlets;

		if (--remaining_frames == 0)

			dst = (void *)runtime->dma_area;

	}

}



static void write_pcm_silence(struct amdtp_stream *s, __be32 *buffer,

			      unsigned int data_blocks)

{

	struct amdtp_dot *p = s->protocol;

	unsigned int channels, i, c;



	channels = p->pcm_channels;



	buffer++;

	for (i = 0; i < data_blocks; ++i) {

		for (c = 0; c < channels; ++c)

			buffer[c] = cpu_to_be32(0x40000000);

		buffer += s->data_block_quadlets;

	}

}



int amdtp_dot_add_pcm_hw_constraints(struct amdtp_stream *s,

				     struct snd_pcm_runtime *runtime)

{

	int err;



	/* This protocol delivers 24 bit data in 32bit data channel. */

	err = snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);

	if (err < 0)

		return err;



	return amdtp_stream_add_pcm_hw_constraints(s, runtime);

}



void amdtp_dot_set_pcm_format(struct amdtp_stream *s, snd_pcm_format_t format)

{

	struct amdtp_dot *p = s->protocol;



	if (WARN_ON(amdtp_stream_pcm_running(s)))

		return;



	switch (format) {

	default:

		WARN_ON(1);

		/* fall through */

	case SNDRV_PCM_FORMAT_S16:

		if (s->direction == AMDTP_OUT_STREAM) {

			p->transfer_samples = write_pcm_s16;

			break;

		}

		WARN_ON(1);

		/* fall through */

	case SNDRV_PCM_FORMAT_S32:

		if (s->direction == AMDTP_OUT_STREAM)

			p->transfer_samples = write_pcm_s32;

		else

			p->transfer_samples = read_pcm_s32;

		break;

	}

}



static unsigned int process_tx_data_blocks(struct amdtp_stream *s,

					   __be32 *buffer,

					   unsigned int data_blocks,

					   unsigned int *syt)

{

	struct amdtp_dot *p = (struct amdtp_dot *)s->protocol;

	struct snd_pcm_substream *pcm;

	unsigned int pcm_frames;



	pcm = ACCESS_ONCE(s->pcm);

	if (pcm) {

		p->transfer_samples(s, pcm, buffer, data_blocks);

		pcm_frames = data_blocks;

	} else {

		pcm_frames = 0;

	}



	/* A place holder for MIDI processing. */



	return pcm_frames;

}



static unsigned int process_rx_data_blocks(struct amdtp_stream *s,

					   __be32 *buffer,

					   unsigned int data_blocks,

					   unsigned int *syt)

{

	struct amdtp_dot *p = (struct amdtp_dot *)s->protocol;

	struct snd_pcm_substream *pcm;

	unsigned int pcm_frames;



	pcm = ACCESS_ONCE(s->pcm);

	if (pcm) {

		p->transfer_samples(s, pcm, buffer, data_blocks);

		pcm_frames = data_blocks;

	} else {

		write_pcm_silence(s, buffer, data_blocks);

		pcm_frames = 0;

	}



	/* A place holder for MIDI processing. */



	return pcm_frames;

}



int amdtp_dot_init(struct amdtp_stream *s, struct fw_unit *unit,

		 enum amdtp_stream_direction dir)

{

	amdtp_stream_process_data_blocks_t process_data_blocks;

	enum cip_flags flags;



	/* Use different mode between incoming/outgoing. */

	if (dir == AMDTP_IN_STREAM) {

		flags = CIP_NONBLOCKING | CIP_SKIP_INIT_DBC_CHECK;

		process_data_blocks = process_tx_data_blocks;

	} else {

		flags = CIP_BLOCKING;

		process_data_blocks = process_rx_data_blocks;

	}



	return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM,

				 process_data_blocks, sizeof(struct amdtp_dot));

}



void amdtp_dot_reset(struct amdtp_stream *s)

{

	struct amdtp_dot *p = s->protocol;



	p->state.carry = 0x00;

	p->state.idx = 0x00;

	p->state.off = 0;

}

sound/firewire/digi00x/digi00x.h

+14 −0
Original line number Diff line number Diff line
@@ -19,8 +19,12 @@ 


#include <sound/core.h>

#include <sound/initval.h>

#include <sound/pcm.h>

#include <sound/pcm_params.h>



#include "../lib.h"

#include "../iso-resources.h"

#include "../amdtp-stream.h"



struct snd_dg00x {

	struct snd_card *card;
@@ -29,4 +33,14 @@ struct snd_dg00x { 
	struct mutex mutex;

};



int amdtp_dot_init(struct amdtp_stream *s, struct fw_unit *unit,

		   enum amdtp_stream_direction dir);

int amdtp_dot_set_parameters(struct amdtp_stream *s, unsigned int rate,

			     unsigned int pcm_channels,

			     unsigned int midi_ports);

void amdtp_dot_reset(struct amdtp_stream *s);

int amdtp_dot_add_pcm_hw_constraints(struct amdtp_stream *s,

				     struct snd_pcm_runtime *runtime);

void amdtp_dot_set_pcm_format(struct amdtp_stream *s, snd_pcm_format_t format);



#endif