sound/firewire/tascam/tascam-stream.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * tascam-stream.c - a part of driver for TASCAM FireWire series
  *
  * Copyright (c) 2015 Takashi Sakamoto
  */

 #include <linux/delay.h>
 #include "tascam.h"

 #define CLOCK_STATUS_MASK      0xffff0000
 #define CLOCK_CONFIG_MASK      0x0000ffff

 #define READY_TIMEOUT_MS	4000

 static int get_clock(struct snd_tscm *tscm, u32 *data)
 {
 	int trial = 0;
 	__be32 reg;
 	int err;

 	while (trial++ < 5) {
 		err = snd_fw_transaction(tscm->unit, TCODE_READ_QUADLET_REQUEST,
 				TSCM_ADDR_BASE + TSCM_OFFSET_CLOCK_STATUS,
 				&reg, sizeof(reg), 0);
 		if (err < 0)
 			return err;

 		*data = be32_to_cpu(reg);
 		if (*data & CLOCK_STATUS_MASK)
 			break;

 		// In intermediate state after changing clock status.
 		msleep(50);
 	}

 	// Still in the intermediate state.
 	if (trial >= 5)
 		return -EAGAIN;

 	return 0;
 }

 static int set_clock(struct snd_tscm *tscm, unsigned int rate,
 		     enum snd_tscm_clock clock)
 {
 	u32 data;
 	__be32 reg;
 	int err;

 	err = get_clock(tscm, &data);
 	if (err < 0)
 		return err;
 	data &= CLOCK_CONFIG_MASK;

 	if (rate > 0) {
 		data &= 0x000000ff;
 		/* Base rate. */
 		if ((rate % 44100) == 0) {
 			data |= 0x00000100;
 			/* Multiplier. */
 			if (rate / 44100 == 2)
 				data |= 0x00008000;
 		} else if ((rate % 48000) == 0) {
 			data |= 0x00000200;
 			/* Multiplier. */
 			if (rate / 48000 == 2)
 				data |= 0x00008000;
 		} else {
 			return -EAGAIN;
 		}
 	}

 	if (clock != INT_MAX) {
 		data &= 0x0000ff00;
 		data |= clock + 1;
 	}

 	reg = cpu_to_be32(data);

 	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				 TSCM_ADDR_BASE + TSCM_OFFSET_CLOCK_STATUS,
 				 &reg, sizeof(reg), 0);
 	if (err < 0)
 		return err;

 	if (data & 0x00008000)
 		reg = cpu_to_be32(0x0000001a);
 	else
 		reg = cpu_to_be32(0x0000000d);

 	return snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				  TSCM_ADDR_BASE + TSCM_OFFSET_MULTIPLEX_MODE,
 				  &reg, sizeof(reg), 0);
 }

 int snd_tscm_stream_get_rate(struct snd_tscm *tscm, unsigned int *rate)
 {
 	u32 data;
 	int err;

 	err = get_clock(tscm, &data);
 	if (err < 0)
 		return err;

 	data = (data & 0xff000000) >> 24;

 	/* Check base rate. */
 	if ((data & 0x0f) == 0x01)
 		*rate = 44100;
 	else if ((data & 0x0f) == 0x02)
 		*rate = 48000;
 	else
 		return -EAGAIN;

 	/* Check multiplier. */
 	if ((data & 0xf0) == 0x80)
 		*rate *= 2;
 	else if ((data & 0xf0) != 0x00)
 		return -EAGAIN;

 	return err;
 }

 int snd_tscm_stream_get_clock(struct snd_tscm *tscm, enum snd_tscm_clock *clock)
 {
 	u32 data;
 	int err;

 	err = get_clock(tscm, &data);
 	if (err < 0)
 		return err;

 	*clock = ((data & 0x00ff0000) >> 16) - 1;
 	if (*clock < 0 || *clock > SND_TSCM_CLOCK_ADAT)
 		return -EIO;

 	return 0;
 }

 static int enable_data_channels(struct snd_tscm *tscm)
 {
 	__be32 reg;
 	u32 data;
 	unsigned int i;
 	int err;

 	data = 0;
 	for (i = 0; i < tscm->spec->pcm_capture_analog_channels; ++i)
 		data |= BIT(i);
 	if (tscm->spec->has_adat)
 		data |= 0x0000ff00;
 	if (tscm->spec->has_spdif)
 		data |= 0x00030000;

 	reg = cpu_to_be32(data);
 	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				 TSCM_ADDR_BASE + TSCM_OFFSET_TX_PCM_CHANNELS,
 				 &reg, sizeof(reg), 0);
 	if (err < 0)
 		return err;

 	data = 0;
 	for (i = 0; i < tscm->spec->pcm_playback_analog_channels; ++i)
 		data |= BIT(i);
 	if (tscm->spec->has_adat)
 		data |= 0x0000ff00;
 	if (tscm->spec->has_spdif)
 		data |= 0x00030000;

 	reg = cpu_to_be32(data);
 	return snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				  TSCM_ADDR_BASE + TSCM_OFFSET_RX_PCM_CHANNELS,
 				  &reg, sizeof(reg), 0);
 }

 static int set_stream_formats(struct snd_tscm *tscm, unsigned int rate)
 {
 	__be32 reg;
 	int err;

 	// Set an option for unknown purpose.
 	reg = cpu_to_be32(0x00200000);
 	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				 TSCM_ADDR_BASE + TSCM_OFFSET_SET_OPTION,
 				 &reg, sizeof(reg), 0);
 	if (err < 0)
 		return err;

 	return enable_data_channels(tscm);
 }

 static void finish_session(struct snd_tscm *tscm)
 {
 	__be32 reg;

 	reg = 0;
 	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 			   TSCM_ADDR_BASE + TSCM_OFFSET_START_STREAMING,
 			   &reg, sizeof(reg), 0);

 	reg = 0;
 	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 			   TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_RX_ON,
 			   &reg, sizeof(reg), 0);

 	// Unregister channels.
 	reg = cpu_to_be32(0x00000000);
 	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 			   TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_TX_CH,
 			   &reg, sizeof(reg), 0);
 	reg = cpu_to_be32(0x00000000);
 	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 			   TSCM_ADDR_BASE + TSCM_OFFSET_UNKNOWN,
 			   &reg, sizeof(reg), 0);
 	reg = cpu_to_be32(0x00000000);
 	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 			   TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_RX_CH,
 			   &reg, sizeof(reg), 0);
 }

 static int begin_session(struct snd_tscm *tscm)
 {
 	__be32 reg;
 	int err;

 	// Register the isochronous channel for transmitting stream.
 	reg = cpu_to_be32(tscm->tx_resources.channel);
 	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				 TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_TX_CH,
 				 &reg, sizeof(reg), 0);
 	if (err < 0)
 		return err;

 	// Unknown.
 	reg = cpu_to_be32(0x00000002);
 	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				 TSCM_ADDR_BASE + TSCM_OFFSET_UNKNOWN,
 				 &reg, sizeof(reg), 0);
 	if (err < 0)
 		return err;

 	// Register the isochronous channel for receiving stream.
 	reg = cpu_to_be32(tscm->rx_resources.channel);
 	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				 TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_RX_CH,
 				 &reg, sizeof(reg), 0);
 	if (err < 0)
 		return err;

 	reg = cpu_to_be32(0x00000001);
 	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				 TSCM_ADDR_BASE + TSCM_OFFSET_START_STREAMING,
 				 &reg, sizeof(reg), 0);
 	if (err < 0)
 		return err;

 	reg = cpu_to_be32(0x00000001);
 	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				 TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_RX_ON,
 				 &reg, sizeof(reg), 0);
 	if (err < 0)
 		return err;

 	// Set an option for unknown purpose.
 	reg = cpu_to_be32(0x00002000);
 	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				 TSCM_ADDR_BASE + TSCM_OFFSET_SET_OPTION,
 				 &reg, sizeof(reg), 0);
 	if (err < 0)
 		return err;

 	// Start multiplexing PCM samples on packets.
 	reg = cpu_to_be32(0x00000001);
 	return snd_fw_transaction(tscm->unit,
 				  TCODE_WRITE_QUADLET_REQUEST,
 				  TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_TX_ON,
 				  &reg, sizeof(reg), 0);
 }

 static int keep_resources(struct snd_tscm *tscm, unsigned int rate,
 			  struct amdtp_stream *stream)
 {
 	struct fw_iso_resources *resources;
 	int err;

 	if (stream == &tscm->tx_stream)
 		resources = &tscm->tx_resources;
 	else
 		resources = &tscm->rx_resources;

 	err = amdtp_tscm_set_parameters(stream, rate);
 	if (err < 0)
 		return err;

 	return fw_iso_resources_allocate(resources,
 				amdtp_stream_get_max_payload(stream),
 				fw_parent_device(tscm->unit)->max_speed);
 }

 static int init_stream(struct snd_tscm *tscm, struct amdtp_stream *s)
 {
 	struct fw_iso_resources *resources;
 	enum amdtp_stream_direction dir;
 	unsigned int pcm_channels;
 	int err;

 	if (s == &tscm->tx_stream) {
 		resources = &tscm->tx_resources;
 		dir = AMDTP_IN_STREAM;
 		pcm_channels = tscm->spec->pcm_capture_analog_channels;
 	} else {
 		resources = &tscm->rx_resources;
 		dir = AMDTP_OUT_STREAM;
 		pcm_channels = tscm->spec->pcm_playback_analog_channels;
 	}

 	if (tscm->spec->has_adat)
 		pcm_channels += 8;
 	if (tscm->spec->has_spdif)
 		pcm_channels += 2;

 	err = fw_iso_resources_init(resources, tscm->unit);
 	if (err < 0)
 		return err;

 	err = amdtp_tscm_init(s, tscm->unit, dir, pcm_channels);
 	if (err < 0)
 		fw_iso_resources_free(resources);

 	return err;
 }

 static void destroy_stream(struct snd_tscm *tscm, struct amdtp_stream *s)
 {
 	amdtp_stream_destroy(s);

 	if (s == &tscm->tx_stream)
 		fw_iso_resources_destroy(&tscm->tx_resources);
 	else
 		fw_iso_resources_destroy(&tscm->rx_resources);
 }

 int snd_tscm_stream_init_duplex(struct snd_tscm *tscm)
 {
 	int err;

 	err = init_stream(tscm, &tscm->tx_stream);
 	if (err < 0)
 		return err;

 	err = init_stream(tscm, &tscm->rx_stream);
 	if (err < 0) {
 		destroy_stream(tscm, &tscm->tx_stream);
 		return err;
 	}

 	err = amdtp_domain_init(&tscm->domain);
 	if (err < 0) {
 		destroy_stream(tscm, &tscm->tx_stream);
 		destroy_stream(tscm, &tscm->rx_stream);
 	}

 	return err;
 }

 // At bus reset, streaming is stopped and some registers are clear.
 void snd_tscm_stream_update_duplex(struct snd_tscm *tscm)
 {
 	amdtp_domain_stop(&tscm->domain);

 	amdtp_stream_pcm_abort(&tscm->tx_stream);
 	amdtp_stream_pcm_abort(&tscm->rx_stream);
 }

 // This function should be called before starting streams or after stopping
 // streams.
 void snd_tscm_stream_destroy_duplex(struct snd_tscm *tscm)
 {
 	amdtp_domain_destroy(&tscm->domain);

 	destroy_stream(tscm, &tscm->rx_stream);
 	destroy_stream(tscm, &tscm->tx_stream);
 }

 int snd_tscm_stream_reserve_duplex(struct snd_tscm *tscm, unsigned int rate,
 				   unsigned int frames_per_period,
 				   unsigned int frames_per_buffer)
 {
 	unsigned int curr_rate;
 	int err;

 	err = snd_tscm_stream_get_rate(tscm, &curr_rate);
 	if (err < 0)
 		return err;

 	if (tscm->substreams_counter == 0 || rate != curr_rate) {
 		amdtp_domain_stop(&tscm->domain);

 		finish_session(tscm);

 		fw_iso_resources_free(&tscm->tx_resources);
 		fw_iso_resources_free(&tscm->rx_resources);

 		err = set_clock(tscm, rate, INT_MAX);
 		if (err < 0)
 			return err;

 		err = keep_resources(tscm, rate, &tscm->tx_stream);
 		if (err < 0)
 			return err;

 		err = keep_resources(tscm, rate, &tscm->rx_stream);
 		if (err < 0) {
 			fw_iso_resources_free(&tscm->tx_resources);
 			return err;
 		}

 		err = amdtp_domain_set_events_per_period(&tscm->domain,
 					frames_per_period, frames_per_buffer);
 		if (err < 0) {
 			fw_iso_resources_free(&tscm->tx_resources);
 			fw_iso_resources_free(&tscm->rx_resources);
 			return err;
 		}

 		tscm->need_long_tx_init_skip = (rate != curr_rate);
 	}

 	return 0;
 }

 int snd_tscm_stream_start_duplex(struct snd_tscm *tscm, unsigned int rate)
 {
 	unsigned int generation = tscm->rx_resources.generation;
 	int err;

 	if (tscm->substreams_counter == 0)
 		return 0;

 	if (amdtp_streaming_error(&tscm->rx_stream) ||
 	    amdtp_streaming_error(&tscm->tx_stream)) {
 		amdtp_domain_stop(&tscm->domain);
 		finish_session(tscm);
 	}

 	if (generation != fw_parent_device(tscm->unit)->card->generation) {
 		err = fw_iso_resources_update(&tscm->tx_resources);
 		if (err < 0)
 			goto error;

 		err = fw_iso_resources_update(&tscm->rx_resources);
 		if (err < 0)
 			goto error;
 	}

 	if (!amdtp_stream_running(&tscm->rx_stream)) {
 		int spd = fw_parent_device(tscm->unit)->max_speed;
 		unsigned int tx_init_skip_cycles;

 		err = set_stream_formats(tscm, rate);
 		if (err < 0)
 			goto error;

 		err = begin_session(tscm);
 		if (err < 0)
 			goto error;

 		err = amdtp_domain_add_stream(&tscm->domain, &tscm->rx_stream,
 					      tscm->rx_resources.channel, spd);
 		if (err < 0)
 			goto error;

 		err = amdtp_domain_add_stream(&tscm->domain, &tscm->tx_stream,
 					      tscm->tx_resources.channel, spd);
 		if (err < 0)
 			goto error;

 		if (tscm->need_long_tx_init_skip)
 			tx_init_skip_cycles = 16000;
 		else
 			tx_init_skip_cycles = 0;

 		// MEMO: Just after starting packet streaming, it transfers packets without any
 		// event. Enough after receiving the sequence of packets, it multiplexes events into
 		// the packet. However, just after changing sampling transfer frequency, it stops
 		// multiplexing during packet transmission. Enough after, it restarts multiplexing
 		// again. The device ignores presentation time expressed by the value of syt field
 		// of CIP header in received packets. The sequence of the number of data blocks per
 		// packet is important for media clock recovery.
 		err = amdtp_domain_start(&tscm->domain, tx_init_skip_cycles, true, true);
 		if (err < 0)
 			return err;

 		if (!amdtp_domain_wait_ready(&tscm->domain, READY_TIMEOUT_MS)) {
 			err = -ETIMEDOUT;
 			goto error;
 		}
 	}

 	return 0;
 error:
 	amdtp_domain_stop(&tscm->domain);
 	finish_session(tscm);

 	return err;
 }

 void snd_tscm_stream_stop_duplex(struct snd_tscm *tscm)
 {
 	if (tscm->substreams_counter == 0) {
 		amdtp_domain_stop(&tscm->domain);
 		finish_session(tscm);

 		fw_iso_resources_free(&tscm->tx_resources);
 		fw_iso_resources_free(&tscm->rx_resources);

 		tscm->need_long_tx_init_skip = false;
 	}
 }

 void snd_tscm_stream_lock_changed(struct snd_tscm *tscm)
 {
 	tscm->dev_lock_changed = true;
 	wake_up(&tscm->hwdep_wait);
 }

 int snd_tscm_stream_lock_try(struct snd_tscm *tscm)
 {
 	int err;

 	spin_lock_irq(&tscm->lock);

 	/* user land lock this */
 	if (tscm->dev_lock_count < 0) {
 		err = -EBUSY;
 		goto end;
 	}

 	/* this is the first time */
 	if (tscm->dev_lock_count++ == 0)
 		snd_tscm_stream_lock_changed(tscm);
 	err = 0;
 end:
 	spin_unlock_irq(&tscm->lock);
 	return err;
 }

 void snd_tscm_stream_lock_release(struct snd_tscm *tscm)
 {
 	spin_lock_irq(&tscm->lock);

 	if (WARN_ON(tscm->dev_lock_count <= 0))
 		goto end;
 	if (--tscm->dev_lock_count == 0)
 		snd_tscm_stream_lock_changed(tscm);
 end:
 	spin_unlock_irq(&tscm->lock);
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* tascam-stream.c - a part of driver for TASCAM FireWire series
	*
	* Copyright (c) 2015 Takashi Sakamoto
	*/

	#include <linux/delay.h>
	#include "tascam.h"

	#define CLOCK_STATUS_MASK 0xffff0000
	#define CLOCK_CONFIG_MASK 0x0000ffff

	#define READY_TIMEOUT_MS 4000

	static int get_clock(struct snd_tscm tscm, u32 data)
	{
	int trial = 0;
	__be32 reg;
	int err;

	while (trial++ < 5) {
	err = snd_fw_transaction(tscm->unit, TCODE_READ_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_CLOCK_STATUS,
	&reg, sizeof(reg), 0);
	if (err < 0)
	return err;

	*data = be32_to_cpu(reg);
	if (*data & CLOCK_STATUS_MASK)
	break;

	// In intermediate state after changing clock status.
	msleep(50);
	}

	// Still in the intermediate state.
	if (trial >= 5)
	return -EAGAIN;

	return 0;
	}

	static int set_clock(struct snd_tscm *tscm, unsigned int rate,
	enum snd_tscm_clock clock)
	{
	u32 data;
	__be32 reg;
	int err;

	err = get_clock(tscm, &data);
	if (err < 0)
	return err;
	data &= CLOCK_CONFIG_MASK;

	if (rate > 0) {
	data &= 0x000000ff;
	/* Base rate. */
	if ((rate % 44100) == 0) {
	data \|= 0x00000100;
	/* Multiplier. */
	if (rate / 44100 == 2)
	data \|= 0x00008000;
	} else if ((rate % 48000) == 0) {
	data \|= 0x00000200;
	/* Multiplier. */
	if (rate / 48000 == 2)
	data \|= 0x00008000;
	} else {
	return -EAGAIN;
	}
	}

	if (clock != INT_MAX) {
	data &= 0x0000ff00;
	data \|= clock + 1;
	}

	reg = cpu_to_be32(data);

	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_CLOCK_STATUS,
	&reg, sizeof(reg), 0);
	if (err < 0)
	return err;

	if (data & 0x00008000)
	reg = cpu_to_be32(0x0000001a);
	else
	reg = cpu_to_be32(0x0000000d);

	return snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_MULTIPLEX_MODE,
	&reg, sizeof(reg), 0);
	}

	int snd_tscm_stream_get_rate(struct snd_tscm tscm, unsigned int rate)
	{
	u32 data;
	int err;

	err = get_clock(tscm, &data);
	if (err < 0)
	return err;

	data = (data & 0xff000000) >> 24;

	/* Check base rate. */
	if ((data & 0x0f) == 0x01)
	*rate = 44100;
	else if ((data & 0x0f) == 0x02)
	*rate = 48000;
	else
	return -EAGAIN;

	/* Check multiplier. */
	if ((data & 0xf0) == 0x80)
	rate = 2;
	else if ((data & 0xf0) != 0x00)
	return -EAGAIN;

	return err;
	}

	int snd_tscm_stream_get_clock(struct snd_tscm tscm, enum snd_tscm_clock clock)
	{
	u32 data;
	int err;

	err = get_clock(tscm, &data);
	if (err < 0)
	return err;

	*clock = ((data & 0x00ff0000) >> 16) - 1;
	if (clock < 0 \|\| clock > SND_TSCM_CLOCK_ADAT)
	return -EIO;

	return 0;
	}

	static int enable_data_channels(struct snd_tscm *tscm)
	{
	__be32 reg;
	u32 data;
	unsigned int i;
	int err;

	data = 0;
	for (i = 0; i < tscm->spec->pcm_capture_analog_channels; ++i)
	data \|= BIT(i);
	if (tscm->spec->has_adat)
	data \|= 0x0000ff00;
	if (tscm->spec->has_spdif)
	data \|= 0x00030000;

	reg = cpu_to_be32(data);
	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_TX_PCM_CHANNELS,
	&reg, sizeof(reg), 0);
	if (err < 0)
	return err;

	data = 0;
	for (i = 0; i < tscm->spec->pcm_playback_analog_channels; ++i)
	data \|= BIT(i);
	if (tscm->spec->has_adat)
	data \|= 0x0000ff00;
	if (tscm->spec->has_spdif)
	data \|= 0x00030000;

	reg = cpu_to_be32(data);
	return snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_RX_PCM_CHANNELS,
	&reg, sizeof(reg), 0);
	}

	static int set_stream_formats(struct snd_tscm *tscm, unsigned int rate)
	{
	__be32 reg;
	int err;

	// Set an option for unknown purpose.
	reg = cpu_to_be32(0x00200000);
	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_SET_OPTION,
	&reg, sizeof(reg), 0);
	if (err < 0)
	return err;

	return enable_data_channels(tscm);
	}

	static void finish_session(struct snd_tscm *tscm)
	{
	__be32 reg;

	reg = 0;
	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_START_STREAMING,
	&reg, sizeof(reg), 0);

	reg = 0;
	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_RX_ON,
	&reg, sizeof(reg), 0);

	// Unregister channels.
	reg = cpu_to_be32(0x00000000);
	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_TX_CH,
	&reg, sizeof(reg), 0);
	reg = cpu_to_be32(0x00000000);
	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_UNKNOWN,
	&reg, sizeof(reg), 0);
	reg = cpu_to_be32(0x00000000);
	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_RX_CH,
	&reg, sizeof(reg), 0);
	}

	static int begin_session(struct snd_tscm *tscm)
	{
	__be32 reg;
	int err;

	// Register the isochronous channel for transmitting stream.
	reg = cpu_to_be32(tscm->tx_resources.channel);
	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_TX_CH,
	&reg, sizeof(reg), 0);
	if (err < 0)
	return err;

	// Unknown.
	reg = cpu_to_be32(0x00000002);
	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_UNKNOWN,
	&reg, sizeof(reg), 0);
	if (err < 0)
	return err;

	// Register the isochronous channel for receiving stream.
	reg = cpu_to_be32(tscm->rx_resources.channel);
	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_RX_CH,
	&reg, sizeof(reg), 0);
	if (err < 0)
	return err;

	reg = cpu_to_be32(0x00000001);
	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_START_STREAMING,
	&reg, sizeof(reg), 0);
	if (err < 0)
	return err;

	reg = cpu_to_be32(0x00000001);
	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_RX_ON,
	&reg, sizeof(reg), 0);
	if (err < 0)
	return err;

	// Set an option for unknown purpose.
	reg = cpu_to_be32(0x00002000);
	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_SET_OPTION,
	&reg, sizeof(reg), 0);
	if (err < 0)
	return err;

	// Start multiplexing PCM samples on packets.
	reg = cpu_to_be32(0x00000001);
	return snd_fw_transaction(tscm->unit,
	TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_ISOC_TX_ON,
	&reg, sizeof(reg), 0);
	}

	static int keep_resources(struct snd_tscm *tscm, unsigned int rate,
	struct amdtp_stream *stream)
	{
	struct fw_iso_resources *resources;
	int err;

	if (stream == &tscm->tx_stream)
	resources = &tscm->tx_resources;
	else
	resources = &tscm->rx_resources;

	err = amdtp_tscm_set_parameters(stream, rate);
	if (err < 0)
	return err;

	return fw_iso_resources_allocate(resources,
	amdtp_stream_get_max_payload(stream),
	fw_parent_device(tscm->unit)->max_speed);
	}

	static int init_stream(struct snd_tscm tscm, struct amdtp_stream s)
	{
	struct fw_iso_resources *resources;
	enum amdtp_stream_direction dir;
	unsigned int pcm_channels;
	int err;

	if (s == &tscm->tx_stream) {
	resources = &tscm->tx_resources;
	dir = AMDTP_IN_STREAM;
	pcm_channels = tscm->spec->pcm_capture_analog_channels;
	} else {
	resources = &tscm->rx_resources;
	dir = AMDTP_OUT_STREAM;
	pcm_channels = tscm->spec->pcm_playback_analog_channels;
	}

	if (tscm->spec->has_adat)
	pcm_channels += 8;
	if (tscm->spec->has_spdif)
	pcm_channels += 2;

	err = fw_iso_resources_init(resources, tscm->unit);
	if (err < 0)
	return err;

	err = amdtp_tscm_init(s, tscm->unit, dir, pcm_channels);
	if (err < 0)
	fw_iso_resources_free(resources);

	return err;
	}

	static void destroy_stream(struct snd_tscm tscm, struct amdtp_stream s)
	{
	amdtp_stream_destroy(s);

	if (s == &tscm->tx_stream)
	fw_iso_resources_destroy(&tscm->tx_resources);
	else
	fw_iso_resources_destroy(&tscm->rx_resources);
	}

	int snd_tscm_stream_init_duplex(struct snd_tscm *tscm)
	{
	int err;

	err = init_stream(tscm, &tscm->tx_stream);
	if (err < 0)
	return err;

	err = init_stream(tscm, &tscm->rx_stream);
	if (err < 0) {
	destroy_stream(tscm, &tscm->tx_stream);
	return err;
	}

	err = amdtp_domain_init(&tscm->domain);
	if (err < 0) {
	destroy_stream(tscm, &tscm->tx_stream);
	destroy_stream(tscm, &tscm->rx_stream);
	}

	return err;
	}

	// At bus reset, streaming is stopped and some registers are clear.
	void snd_tscm_stream_update_duplex(struct snd_tscm *tscm)
	{
	amdtp_domain_stop(&tscm->domain);

	amdtp_stream_pcm_abort(&tscm->tx_stream);
	amdtp_stream_pcm_abort(&tscm->rx_stream);
	}

	// This function should be called before starting streams or after stopping
	// streams.
	void snd_tscm_stream_destroy_duplex(struct snd_tscm *tscm)
	{
	amdtp_domain_destroy(&tscm->domain);

	destroy_stream(tscm, &tscm->rx_stream);
	destroy_stream(tscm, &tscm->tx_stream);
	}

	int snd_tscm_stream_reserve_duplex(struct snd_tscm *tscm, unsigned int rate,
	unsigned int frames_per_period,
	unsigned int frames_per_buffer)
	{
	unsigned int curr_rate;
	int err;

	err = snd_tscm_stream_get_rate(tscm, &curr_rate);
	if (err < 0)
	return err;

	if (tscm->substreams_counter == 0 \|\| rate != curr_rate) {
	amdtp_domain_stop(&tscm->domain);

	finish_session(tscm);

	fw_iso_resources_free(&tscm->tx_resources);
	fw_iso_resources_free(&tscm->rx_resources);

	err = set_clock(tscm, rate, INT_MAX);
	if (err < 0)
	return err;

	err = keep_resources(tscm, rate, &tscm->tx_stream);
	if (err < 0)
	return err;

	err = keep_resources(tscm, rate, &tscm->rx_stream);
	if (err < 0) {
	fw_iso_resources_free(&tscm->tx_resources);
	return err;
	}

	err = amdtp_domain_set_events_per_period(&tscm->domain,
	frames_per_period, frames_per_buffer);
	if (err < 0) {
	fw_iso_resources_free(&tscm->tx_resources);
	fw_iso_resources_free(&tscm->rx_resources);
	return err;
	}

	tscm->need_long_tx_init_skip = (rate != curr_rate);
	}

	return 0;
	}

	int snd_tscm_stream_start_duplex(struct snd_tscm *tscm, unsigned int rate)
	{
	unsigned int generation = tscm->rx_resources.generation;
	int err;

	if (tscm->substreams_counter == 0)
	return 0;

	if (amdtp_streaming_error(&tscm->rx_stream) \|\|
	amdtp_streaming_error(&tscm->tx_stream)) {
	amdtp_domain_stop(&tscm->domain);
	finish_session(tscm);
	}

	if (generation != fw_parent_device(tscm->unit)->card->generation) {
	err = fw_iso_resources_update(&tscm->tx_resources);
	if (err < 0)
	goto error;

	err = fw_iso_resources_update(&tscm->rx_resources);
	if (err < 0)
	goto error;
	}

	if (!amdtp_stream_running(&tscm->rx_stream)) {
	int spd = fw_parent_device(tscm->unit)->max_speed;
	unsigned int tx_init_skip_cycles;

	err = set_stream_formats(tscm, rate);
	if (err < 0)
	goto error;

	err = begin_session(tscm);
	if (err < 0)
	goto error;

	err = amdtp_domain_add_stream(&tscm->domain, &tscm->rx_stream,
	tscm->rx_resources.channel, spd);
	if (err < 0)
	goto error;

	err = amdtp_domain_add_stream(&tscm->domain, &tscm->tx_stream,
	tscm->tx_resources.channel, spd);
	if (err < 0)
	goto error;

	if (tscm->need_long_tx_init_skip)
	tx_init_skip_cycles = 16000;
	else
	tx_init_skip_cycles = 0;

	// MEMO: Just after starting packet streaming, it transfers packets without any
	// event. Enough after receiving the sequence of packets, it multiplexes events into
	// the packet. However, just after changing sampling transfer frequency, it stops
	// multiplexing during packet transmission. Enough after, it restarts multiplexing
	// again. The device ignores presentation time expressed by the value of syt field
	// of CIP header in received packets. The sequence of the number of data blocks per
	// packet is important for media clock recovery.
	err = amdtp_domain_start(&tscm->domain, tx_init_skip_cycles, true, true);
	if (err < 0)
	return err;

	if (!amdtp_domain_wait_ready(&tscm->domain, READY_TIMEOUT_MS)) {
	err = -ETIMEDOUT;
	goto error;
	}
	}

	return 0;
	error:
	amdtp_domain_stop(&tscm->domain);
	finish_session(tscm);

	return err;
	}

	void snd_tscm_stream_stop_duplex(struct snd_tscm *tscm)
	{
	if (tscm->substreams_counter == 0) {
	amdtp_domain_stop(&tscm->domain);
	finish_session(tscm);

	fw_iso_resources_free(&tscm->tx_resources);
	fw_iso_resources_free(&tscm->rx_resources);

	tscm->need_long_tx_init_skip = false;
	}
	}

	void snd_tscm_stream_lock_changed(struct snd_tscm *tscm)
	{
	tscm->dev_lock_changed = true;
	wake_up(&tscm->hwdep_wait);
	}

	int snd_tscm_stream_lock_try(struct snd_tscm *tscm)
	{
	int err;

	spin_lock_irq(&tscm->lock);

	/* user land lock this */
	if (tscm->dev_lock_count < 0) {
	err = -EBUSY;
	goto end;
	}

	/* this is the first time */
	if (tscm->dev_lock_count++ == 0)
	snd_tscm_stream_lock_changed(tscm);
	err = 0;
	end:
	spin_unlock_irq(&tscm->lock);
	return err;
	}

	void snd_tscm_stream_lock_release(struct snd_tscm *tscm)
	{
	spin_lock_irq(&tscm->lock);

	if (WARN_ON(tscm->dev_lock_count <= 0))
	goto end;
	if (--tscm->dev_lock_count == 0)
	snd_tscm_stream_lock_changed(tscm);
	end:
	spin_unlock_irq(&tscm->lock);
	}