sound/firewire/tascam/tascam-transaction.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  * tascam-transaction.c - a part of driver for TASCAM FireWire series
  *
  * Copyright (c) 2015 Takashi Sakamoto
  *
  * Licensed under the terms of the GNU General Public License, version 2.
  */

 #include "tascam.h"

 /*
  * When return minus value, given argument is not MIDI status.
  * When return 0, given argument is a beginning of system exclusive.
  * When return the others, given argument is MIDI data.
  */
 static inline int calculate_message_bytes(u8 status)
 {
 	switch (status) {
 	case 0xf6:	/* Tune request. */
 	case 0xf8:	/* Timing clock. */
 	case 0xfa:	/* Start. */
 	case 0xfb:	/* Continue. */
 	case 0xfc:	/* Stop. */
 	case 0xfe:	/* Active sensing. */
 	case 0xff:	/* System reset. */
 		return 1;
 	case 0xf1:	/* MIDI time code quarter frame. */
 	case 0xf3:	/* Song select. */
 		return 2;
 	case 0xf2:	/* Song position pointer. */
 		return 3;
 	case 0xf0:	/* Exclusive. */
 		return 0;
 	case 0xf7:	/* End of exclusive. */
 		break;
 	case 0xf4:	/* Undefined. */
 	case 0xf5:	/* Undefined. */
 	case 0xf9:	/* Undefined. */
 	case 0xfd:	/* Undefined. */
 		break;
 	default:
 		switch (status & 0xf0) {
 		case 0x80:	/* Note on. */
 		case 0x90:	/* Note off. */
 		case 0xa0:	/* Polyphonic key pressure. */
 		case 0xb0:	/* Control change and Mode change. */
 		case 0xe0:	/* Pitch bend change. */
 			return 3;
 		case 0xc0:	/* Program change. */
 		case 0xd0:	/* Channel pressure. */
 			return 2;
 		default:
 		break;
 		}
 	break;
 	}

 	return -EINVAL;
 }

 static int fill_message(struct snd_fw_async_midi_port *port,
 			struct snd_rawmidi_substream *substream)
 {
 	int i, len, consume;
 	u8 *label, *msg;
 	u8 status;

 	/* The first byte is used for label, the rest for MIDI bytes. */
 	label = port->buf;
 	msg = port->buf + 1;

 	consume = snd_rawmidi_transmit_peek(substream, msg, 3);
 	if (consume == 0)
 		return 0;

 	/* On exclusive message. */
 	if (port->on_sysex) {
 		/* Seek the end of exclusives. */
 		for (i = 0; i < consume; ++i) {
 			if (msg[i] == 0xf7) {
 				port->on_sysex = false;
 				break;
 			}
 		}

 		/* At the end of exclusive message, use label 0x07. */
 		if (!port->on_sysex) {
 			consume = i + 1;
 			*label = (substream->number << 4) | 0x07;
 		/* During exclusive message, use label 0x04. */
 		} else if (consume == 3) {
 			*label = (substream->number << 4) | 0x04;
 		/* We need to fill whole 3 bytes. Go to next change. */
 		} else {
 			return 0;
 		}

 		len = consume;
 	} else {
 		/* The beginning of exclusives. */
 		if (msg[0] == 0xf0) {
 			/* Transfer it in next chance in another condition. */
 			port->on_sysex = true;
 			return 0;
 		} else {
 			/* On running-status. */
 			if ((msg[0] & 0x80) != 0x80)
 				status = port->running_status;
 			else
 				status = msg[0];

 			/* Calculate consume bytes. */
 			len = calculate_message_bytes(status);
 			if (len <= 0)
 				return 0;

 			/* On running-status. */
 			if ((msg[0] & 0x80) != 0x80) {
 				/* Enough MIDI bytes were not retrieved. */
 				if (consume < len - 1)
 					return 0;
 				consume = len - 1;

 				msg[2] = msg[1];
 				msg[1] = msg[0];
 				msg[0] = port->running_status;
 			} else {
 				/* Enough MIDI bytes were not retrieved. */
 				if (consume < len)
 					return 0;
 				consume = len;

 				port->running_status = msg[0];
 			}
 		}

 		*label = (substream->number << 4) | (msg[0] >> 4);
 	}

 	if (len > 0 && len < 3)
 		memset(msg + len, 0, 3 - len);

 	return consume;
 }

 static void async_midi_port_callback(struct fw_card *card, int rcode,
 				     void *data, size_t length,
 				     void *callback_data)
 {
 	struct snd_fw_async_midi_port *port = callback_data;
 	struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream);

 	/* This port is closed. */
 	if (substream == NULL)
 		return;

 	if (rcode == RCODE_COMPLETE)
 		snd_rawmidi_transmit_ack(substream, port->consume_bytes);
 	else if (!rcode_is_permanent_error(rcode))
 		/* To start next transaction immediately for recovery. */
 		port->next_ktime = 0;
 	else
 		/* Don't continue processing. */
 		port->error = true;

 	port->idling = true;

 	if (!snd_rawmidi_transmit_empty(substream))
 		schedule_work(&port->work);
 }

 static void midi_port_work(struct work_struct *work)
 {
 	struct snd_fw_async_midi_port *port =
 			container_of(work, struct snd_fw_async_midi_port, work);
 	struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream);
 	int generation;

 	/* Under transacting or error state. */
 	if (!port->idling || port->error)
 		return;

 	/* Nothing to do. */
 	if (substream == NULL || snd_rawmidi_transmit_empty(substream))
 		return;

 	/* Do it in next chance. */
 	if (ktime_after(port->next_ktime, ktime_get())) {
 		schedule_work(&port->work);
 		return;
 	}

 	/*
 	 * Fill the buffer. The callee must use snd_rawmidi_transmit_peek().
 	 * Later, snd_rawmidi_transmit_ack() is called.
 	 */
 	memset(port->buf, 0, 4);
 	port->consume_bytes = fill_message(port, substream);
 	if (port->consume_bytes <= 0) {
 		/* Do it in next chance, immediately. */
 		if (port->consume_bytes == 0) {
 			port->next_ktime = 0;
 			schedule_work(&port->work);
 		} else {
 			/* Fatal error. */
 			port->error = true;
 		}
 		return;
 	}

 	/* Set interval to next transaction. */
 	port->next_ktime = ktime_add_ns(ktime_get(),
 			port->consume_bytes * 8 * (NSEC_PER_SEC / 31250));

 	/* Start this transaction. */
 	port->idling = false;

 	/*
 	 * In Linux FireWire core, when generation is updated with memory
 	 * barrier, node id has already been updated. In this module, After
 	 * this smp_rmb(), load/store instructions to memory are completed.
 	 * Thus, both of generation and node id are available with recent
 	 * values. This is a light-serialization solution to handle bus reset
 	 * events on IEEE 1394 bus.
 	 */
 	generation = port->parent->generation;
 	smp_rmb();

 	fw_send_request(port->parent->card, &port->transaction,
 			TCODE_WRITE_QUADLET_REQUEST,
 			port->parent->node_id, generation,
 			port->parent->max_speed,
 			TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_RX_QUAD,
 			port->buf, 4, async_midi_port_callback,
 			port);
 }

 void snd_fw_async_midi_port_init(struct snd_fw_async_midi_port *port)
 {
 	port->idling = true;
 	port->error = false;
 	port->running_status = 0;
 	port->on_sysex = false;
 }

 static void handle_midi_tx(struct fw_card *card, struct fw_request *request,
 			   int tcode, int destination, int source,
 			   int generation, unsigned long long offset,
 			   void *data, size_t length, void *callback_data)
 {
 	struct snd_tscm *tscm = callback_data;
 	u32 *buf = (u32 *)data;
 	unsigned int messages;
 	unsigned int i;
 	unsigned int port;
 	struct snd_rawmidi_substream *substream;
 	u8 *b;
 	int bytes;

 	if (offset != tscm->async_handler.offset)
 		goto end;

 	messages = length / 8;
 	for (i = 0; i < messages; i++) {
 		b = (u8 *)(buf + i * 2);

 		port = b[0] >> 4;
 		/* TODO: support virtual MIDI ports. */
 		if (port >= tscm->spec->midi_capture_ports)
 			goto end;

 		/* Assume the message length. */
 		bytes = calculate_message_bytes(b[1]);
 		/* On MIDI data or exclusives. */
 		if (bytes <= 0) {
 			/* Seek the end of exclusives. */
 			for (bytes = 1; bytes < 4; bytes++) {
 				if (b[bytes] == 0xf7)
 					break;
 			}
 			if (bytes == 4)
 				bytes = 3;
 		}

 		substream = ACCESS_ONCE(tscm->tx_midi_substreams[port]);
 		if (substream != NULL)
 			snd_rawmidi_receive(substream, b + 1, bytes);
 	}
 end:
 	fw_send_response(card, request, RCODE_COMPLETE);
 }

 int snd_tscm_transaction_register(struct snd_tscm *tscm)
 {
 	static const struct fw_address_region resp_register_region = {
 		.start	= 0xffffe0000000ull,
 		.end	= 0xffffe000ffffull,
 	};
 	unsigned int i;
 	int err;

 	/*
 	 * Usually, two quadlets are transferred by one transaction. The first
 	 * quadlet has MIDI messages, the rest includes timestamp.
 	 * Sometimes, 8 set of the data is transferred by a block transaction.
 	 */
 	tscm->async_handler.length = 8 * 8;
 	tscm->async_handler.address_callback = handle_midi_tx;
 	tscm->async_handler.callback_data = tscm;

 	err = fw_core_add_address_handler(&tscm->async_handler,
 					  &resp_register_region);
 	if (err < 0)
 		return err;

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

 	for (i = 0; i < TSCM_MIDI_OUT_PORT_MAX; i++) {
 		tscm->out_ports[i].parent = fw_parent_device(tscm->unit);
 		tscm->out_ports[i].next_ktime = 0;
 		INIT_WORK(&tscm->out_ports[i].work, midi_port_work);
 	}

 	return err;
 error:
 	fw_core_remove_address_handler(&tscm->async_handler);
 	tscm->async_handler.callback_data = NULL;
 	return err;
 }

 /* At bus reset, these registers are cleared. */
 int snd_tscm_transaction_reregister(struct snd_tscm *tscm)
 {
 	struct fw_device *device = fw_parent_device(tscm->unit);
 	__be32 reg;
 	int err;

 	/* Register messaging address. Block transaction is not allowed. */
 	reg = cpu_to_be32((device->card->node_id << 16) |
 			  (tscm->async_handler.offset >> 32));
 	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				 TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_TX_ADDR_HI,
 				 &reg, sizeof(reg), 0);
 	if (err < 0)
 		return err;

 	reg = cpu_to_be32(tscm->async_handler.offset);
 	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				 TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_TX_ADDR_LO,
 				 &reg, sizeof(reg), 0);
 	if (err < 0)
 		return err;

 	/* Turn on messaging. */
 	reg = cpu_to_be32(0x00000001);
 	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				  TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_TX_ON,
 				  &reg, sizeof(reg), 0);
 	if (err < 0)
 		return err;

 	/* Turn on FireWire LED. */
 	reg = cpu_to_be32(0x0001008e);
 	return snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 				  TSCM_ADDR_BASE + TSCM_OFFSET_LED_POWER,
 				  &reg, sizeof(reg), 0);
 }

 void snd_tscm_transaction_unregister(struct snd_tscm *tscm)
 {
 	__be32 reg;

 	if (tscm->async_handler.callback_data == NULL)
 		return;

 	/* Turn off FireWire LED. */
 	reg = cpu_to_be32(0x0000008e);
 	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 			   TSCM_ADDR_BASE + TSCM_OFFSET_LED_POWER,
 			   &reg, sizeof(reg), 0);

 	/* Turn off messaging. */
 	reg = cpu_to_be32(0x00000000);
 	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 			   TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_TX_ON,
 			   &reg, sizeof(reg), 0);

 	/* Unregister the address. */
 	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 			   TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_TX_ADDR_HI,
 			   &reg, sizeof(reg), 0);
 	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
 			   TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_TX_ADDR_LO,
 			   &reg, sizeof(reg), 0);

 	fw_core_remove_address_handler(&tscm->async_handler);
 	tscm->async_handler.callback_data = NULL;
 }
	/*
	* tascam-transaction.c - a part of driver for TASCAM FireWire series
	*
	* Copyright (c) 2015 Takashi Sakamoto
	*
	* Licensed under the terms of the GNU General Public License, version 2.
	*/

	#include "tascam.h"

	/*
	* When return minus value, given argument is not MIDI status.
	* When return 0, given argument is a beginning of system exclusive.
	* When return the others, given argument is MIDI data.
	*/
	static inline int calculate_message_bytes(u8 status)
	{
	switch (status) {
	case 0xf6: /* Tune request. */
	case 0xf8: /* Timing clock. */
	case 0xfa: /* Start. */
	case 0xfb: /* Continue. */
	case 0xfc: /* Stop. */
	case 0xfe: /* Active sensing. */
	case 0xff: /* System reset. */
	return 1;
	case 0xf1: /* MIDI time code quarter frame. */
	case 0xf3: /* Song select. */
	return 2;
	case 0xf2: /* Song position pointer. */
	return 3;
	case 0xf0: /* Exclusive. */
	return 0;
	case 0xf7: /* End of exclusive. */
	break;
	case 0xf4: /* Undefined. */
	case 0xf5: /* Undefined. */
	case 0xf9: /* Undefined. */
	case 0xfd: /* Undefined. */
	break;
	default:
	switch (status & 0xf0) {
	case 0x80: /* Note on. */
	case 0x90: /* Note off. */
	case 0xa0: /* Polyphonic key pressure. */
	case 0xb0: /* Control change and Mode change. */
	case 0xe0: /* Pitch bend change. */
	return 3;
	case 0xc0: /* Program change. */
	case 0xd0: /* Channel pressure. */
	return 2;
	default:
	break;
	}
	break;
	}

	return -EINVAL;
	}

	static int fill_message(struct snd_fw_async_midi_port *port,
	struct snd_rawmidi_substream *substream)
	{
	int i, len, consume;
	u8 label, msg;
	u8 status;

	/* The first byte is used for label, the rest for MIDI bytes. */
	label = port->buf;
	msg = port->buf + 1;

	consume = snd_rawmidi_transmit_peek(substream, msg, 3);
	if (consume == 0)
	return 0;

	/* On exclusive message. */
	if (port->on_sysex) {
	/* Seek the end of exclusives. */
	for (i = 0; i < consume; ++i) {
	if (msg[i] == 0xf7) {
	port->on_sysex = false;
	break;
	}
	}

	/* At the end of exclusive message, use label 0x07. */
	if (!port->on_sysex) {
	consume = i + 1;
	*label = (substream->number << 4) \| 0x07;
	/* During exclusive message, use label 0x04. */
	} else if (consume == 3) {
	*label = (substream->number << 4) \| 0x04;
	/* We need to fill whole 3 bytes. Go to next change. */
	} else {
	return 0;
	}

	len = consume;
	} else {
	/* The beginning of exclusives. */
	if (msg[0] == 0xf0) {
	/* Transfer it in next chance in another condition. */
	port->on_sysex = true;
	return 0;
	} else {
	/* On running-status. */
	if ((msg[0] & 0x80) != 0x80)
	status = port->running_status;
	else
	status = msg[0];

	/* Calculate consume bytes. */
	len = calculate_message_bytes(status);
	if (len <= 0)
	return 0;

	/* On running-status. */
	if ((msg[0] & 0x80) != 0x80) {
	/* Enough MIDI bytes were not retrieved. */
	if (consume < len - 1)
	return 0;
	consume = len - 1;

	msg[2] = msg[1];
	msg[1] = msg[0];
	msg[0] = port->running_status;
	} else {
	/* Enough MIDI bytes were not retrieved. */
	if (consume < len)
	return 0;
	consume = len;

	port->running_status = msg[0];
	}
	}

	*label = (substream->number << 4) \| (msg[0] >> 4);
	}

	if (len > 0 && len < 3)
	memset(msg + len, 0, 3 - len);

	return consume;
	}

	static void async_midi_port_callback(struct fw_card *card, int rcode,
	void *data, size_t length,
	void *callback_data)
	{
	struct snd_fw_async_midi_port *port = callback_data;
	struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream);

	/* This port is closed. */
	if (substream == NULL)
	return;

	if (rcode == RCODE_COMPLETE)
	snd_rawmidi_transmit_ack(substream, port->consume_bytes);
	else if (!rcode_is_permanent_error(rcode))
	/* To start next transaction immediately for recovery. */
	port->next_ktime = 0;
	else
	/* Don't continue processing. */
	port->error = true;

	port->idling = true;

	if (!snd_rawmidi_transmit_empty(substream))
	schedule_work(&port->work);
	}

	static void midi_port_work(struct work_struct *work)
	{
	struct snd_fw_async_midi_port *port =
	container_of(work, struct snd_fw_async_midi_port, work);
	struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream);
	int generation;

	/* Under transacting or error state. */
	if (!port->idling \|\| port->error)
	return;

	/* Nothing to do. */
	if (substream == NULL \|\| snd_rawmidi_transmit_empty(substream))
	return;

	/* Do it in next chance. */
	if (ktime_after(port->next_ktime, ktime_get())) {
	schedule_work(&port->work);
	return;
	}

	/*
	* Fill the buffer. The callee must use snd_rawmidi_transmit_peek().
	* Later, snd_rawmidi_transmit_ack() is called.
	*/
	memset(port->buf, 0, 4);
	port->consume_bytes = fill_message(port, substream);
	if (port->consume_bytes <= 0) {
	/* Do it in next chance, immediately. */
	if (port->consume_bytes == 0) {
	port->next_ktime = 0;
	schedule_work(&port->work);
	} else {
	/* Fatal error. */
	port->error = true;
	}
	return;
	}

	/* Set interval to next transaction. */
	port->next_ktime = ktime_add_ns(ktime_get(),
	port->consume_bytes * 8 * (NSEC_PER_SEC / 31250));

	/* Start this transaction. */
	port->idling = false;

	/*
	* In Linux FireWire core, when generation is updated with memory
	* barrier, node id has already been updated. In this module, After
	* this smp_rmb(), load/store instructions to memory are completed.
	* Thus, both of generation and node id are available with recent
	* values. This is a light-serialization solution to handle bus reset
	* events on IEEE 1394 bus.
	*/
	generation = port->parent->generation;
	smp_rmb();

	fw_send_request(port->parent->card, &port->transaction,
	TCODE_WRITE_QUADLET_REQUEST,
	port->parent->node_id, generation,
	port->parent->max_speed,
	TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_RX_QUAD,
	port->buf, 4, async_midi_port_callback,
	port);
	}

	void snd_fw_async_midi_port_init(struct snd_fw_async_midi_port *port)
	{
	port->idling = true;
	port->error = false;
	port->running_status = 0;
	port->on_sysex = false;
	}

	static void handle_midi_tx(struct fw_card card, struct fw_request request,
	int tcode, int destination, int source,
	int generation, unsigned long long offset,
	void data, size_t length, void callback_data)
	{
	struct snd_tscm *tscm = callback_data;
	u32 buf = (u32 )data;
	unsigned int messages;
	unsigned int i;
	unsigned int port;
	struct snd_rawmidi_substream *substream;
	u8 *b;
	int bytes;

	if (offset != tscm->async_handler.offset)
	goto end;

	messages = length / 8;
	for (i = 0; i < messages; i++) {
	b = (u8 )(buf + i 2);

	port = b[0] >> 4;
	/* TODO: support virtual MIDI ports. */
	if (port >= tscm->spec->midi_capture_ports)
	goto end;

	/* Assume the message length. */
	bytes = calculate_message_bytes(b[1]);
	/* On MIDI data or exclusives. */
	if (bytes <= 0) {
	/* Seek the end of exclusives. */
	for (bytes = 1; bytes < 4; bytes++) {
	if (b[bytes] == 0xf7)
	break;
	}
	if (bytes == 4)
	bytes = 3;
	}

	substream = ACCESS_ONCE(tscm->tx_midi_substreams[port]);
	if (substream != NULL)
	snd_rawmidi_receive(substream, b + 1, bytes);
	}
	end:
	fw_send_response(card, request, RCODE_COMPLETE);
	}

	int snd_tscm_transaction_register(struct snd_tscm *tscm)
	{
	static const struct fw_address_region resp_register_region = {
	.start = 0xffffe0000000ull,
	.end = 0xffffe000ffffull,
	};
	unsigned int i;
	int err;

	/*
	* Usually, two quadlets are transferred by one transaction. The first
	* quadlet has MIDI messages, the rest includes timestamp.
	* Sometimes, 8 set of the data is transferred by a block transaction.
	*/
	tscm->async_handler.length = 8 * 8;
	tscm->async_handler.address_callback = handle_midi_tx;
	tscm->async_handler.callback_data = tscm;

	err = fw_core_add_address_handler(&tscm->async_handler,
	&resp_register_region);
	if (err < 0)
	return err;

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

	for (i = 0; i < TSCM_MIDI_OUT_PORT_MAX; i++) {
	tscm->out_ports[i].parent = fw_parent_device(tscm->unit);
	tscm->out_ports[i].next_ktime = 0;
	INIT_WORK(&tscm->out_ports[i].work, midi_port_work);
	}

	return err;
	error:
	fw_core_remove_address_handler(&tscm->async_handler);
	tscm->async_handler.callback_data = NULL;
	return err;
	}

	/* At bus reset, these registers are cleared. */
	int snd_tscm_transaction_reregister(struct snd_tscm *tscm)
	{
	struct fw_device *device = fw_parent_device(tscm->unit);
	__be32 reg;
	int err;

	/* Register messaging address. Block transaction is not allowed. */
	reg = cpu_to_be32((device->card->node_id << 16) \|
	(tscm->async_handler.offset >> 32));
	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_TX_ADDR_HI,
	&reg, sizeof(reg), 0);
	if (err < 0)
	return err;

	reg = cpu_to_be32(tscm->async_handler.offset);
	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_TX_ADDR_LO,
	&reg, sizeof(reg), 0);
	if (err < 0)
	return err;

	/* Turn on messaging. */
	reg = cpu_to_be32(0x00000001);
	err = snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_TX_ON,
	&reg, sizeof(reg), 0);
	if (err < 0)
	return err;

	/* Turn on FireWire LED. */
	reg = cpu_to_be32(0x0001008e);
	return snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_LED_POWER,
	&reg, sizeof(reg), 0);
	}

	void snd_tscm_transaction_unregister(struct snd_tscm *tscm)
	{
	__be32 reg;

	if (tscm->async_handler.callback_data == NULL)
	return;

	/* Turn off FireWire LED. */
	reg = cpu_to_be32(0x0000008e);
	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_LED_POWER,
	&reg, sizeof(reg), 0);

	/* Turn off messaging. */
	reg = cpu_to_be32(0x00000000);
	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_TX_ON,
	&reg, sizeof(reg), 0);

	/* Unregister the address. */
	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_TX_ADDR_HI,
	&reg, sizeof(reg), 0);
	snd_fw_transaction(tscm->unit, TCODE_WRITE_QUADLET_REQUEST,
	TSCM_ADDR_BASE + TSCM_OFFSET_MIDI_TX_ADDR_LO,
	&reg, sizeof(reg), 0);

	fw_core_remove_address_handler(&tscm->async_handler);
	tscm->async_handler.callback_data = NULL;
	}