sound/firewire/scs1x.c - kernel/msm-4.9 - Gitiles

 /*
  * Stanton Control System 1 MIDI driver
  *
  * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
  * Licensed under the terms of the GNU General Public License, version 2.
  */

 #include <linux/device.h>
 #include <linux/firewire.h>
 #include <linux/firewire-constants.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/wait.h>
 #include <sound/core.h>
 #include <sound/initval.h>
 #include <sound/rawmidi.h>
 #include "lib.h"

 #define OUI_STANTON	0x001260
 #define MODEL_SCS_1M	0x001000
 #define MODEL_SCS_1D	0x002000

 #define HSS1394_ADDRESS			0xc007dedadadaULL
 #define HSS1394_MAX_PACKET_SIZE		64

 #define HSS1394_TAG_USER_DATA		0x00
 #define HSS1394_TAG_CHANGE_ADDRESS	0xf1

 struct scs {
 	struct snd_card *card;
 	struct fw_unit *unit;
 	struct fw_address_handler hss_handler;
 	struct fw_transaction transaction;
 	bool transaction_running;
 	bool output_idle;
 	u8 output_status;
 	u8 output_bytes;
 	bool output_escaped;
 	bool output_escape_high_nibble;
 	u8 input_escape_count;
 	struct snd_rawmidi_substream *output;
 	struct snd_rawmidi_substream *input;
 	struct tasklet_struct tasklet;
 	wait_queue_head_t idle_wait;
 	u8 *buffer;
 };

 static const u8 sysex_escape_prefix[] = {
 	0xf0,			/* SysEx begin */
 	0x00, 0x01, 0x60,	/* Stanton DJ */
 	0x48, 0x53, 0x53,	/* "HSS" */
 };

 static int scs_output_open(struct snd_rawmidi_substream *stream)
 {
 	struct scs *scs = stream->rmidi->private_data;

 	scs->output_status = 0;
 	scs->output_bytes = 1;
 	scs->output_escaped = false;

 	return 0;
 }

 static int scs_output_close(struct snd_rawmidi_substream *stream)
 {
 	return 0;
 }

 static void scs_output_trigger(struct snd_rawmidi_substream *stream, int up)
 {
 	struct scs *scs = stream->rmidi->private_data;

 	ACCESS_ONCE(scs->output) = up ? stream : NULL;
 	if (up) {
 		scs->output_idle = false;
 		tasklet_schedule(&scs->tasklet);
 	}
 }

 static void scs_write_callback(struct fw_card *card, int rcode,
 			       void *data, size_t length, void *callback_data)
 {
 	struct scs *scs = callback_data;

 	if (rcode == RCODE_GENERATION) {
 		/* TODO: retry this packet */
 	}

 	scs->transaction_running = false;
 	tasklet_schedule(&scs->tasklet);
 }

 static bool is_valid_running_status(u8 status)
 {
 	return status >= 0x80 && status <= 0xef;
 }

 static bool is_one_byte_cmd(u8 status)
 {
 	return status == 0xf6 ||
 	       status >= 0xf8;
 }

 static bool is_two_bytes_cmd(u8 status)
 {
 	return (status >= 0xc0 && status <= 0xdf) ||
 	       status == 0xf1 ||
 	       status == 0xf3;
 }

 static bool is_three_bytes_cmd(u8 status)
 {
 	return (status >= 0x80 && status <= 0xbf) ||
 	       (status >= 0xe0 && status <= 0xef) ||
 	       status == 0xf2;
 }

 static bool is_invalid_cmd(u8 status)
 {
 	return status == 0xf4 ||
 	       status == 0xf5 ||
 	       status == 0xf9 ||
 	       status == 0xfd;
 }

 static void scs_output_tasklet(unsigned long data)
 {
 	struct scs *scs = (void *)data;
 	struct snd_rawmidi_substream *stream;
 	unsigned int i;
 	u8 byte;
 	struct fw_device *dev;
 	int generation;

 	if (scs->transaction_running)
 		return;

 	stream = ACCESS_ONCE(scs->output);
 	if (!stream) {
 		scs->output_idle = true;
 		wake_up(&scs->idle_wait);
 		return;
 	}

 	i = scs->output_bytes;
 	for (;;) {
 		if (snd_rawmidi_transmit(stream, &byte, 1) != 1) {
 			scs->output_bytes = i;
 			scs->output_idle = true;
 			wake_up(&scs->idle_wait);
 			return;
 		}
 		/*
 		 * Convert from real MIDI to what I think the device expects (no
 		 * running status, one command per packet, unescaped SysExs).
 		 */
 		if (scs->output_escaped && byte < 0x80) {
 			if (scs->output_escape_high_nibble) {
 				if (i < HSS1394_MAX_PACKET_SIZE) {
 					scs->buffer[i] = byte << 4;
 					scs->output_escape_high_nibble = false;
 				}
 			} else {
 				scs->buffer[i++] |= byte & 0x0f;
 				scs->output_escape_high_nibble = true;
 			}
 		} else if (byte < 0x80) {
 			if (i == 1) {
 				if (!is_valid_running_status(scs->output_status))
 					continue;
 				scs->buffer[0] = HSS1394_TAG_USER_DATA;
 				scs->buffer[i++] = scs->output_status;
 			}
 			scs->buffer[i++] = byte;
 			if ((i == 3 && is_two_bytes_cmd(scs->output_status)) ||
 			    (i == 4 && is_three_bytes_cmd(scs->output_status)))
 				break;
 			if (i == 1 + ARRAY_SIZE(sysex_escape_prefix) &&
 			    !memcmp(scs->buffer + 1, sysex_escape_prefix,
 				    ARRAY_SIZE(sysex_escape_prefix))) {
 				scs->output_escaped = true;
 				scs->output_escape_high_nibble = true;
 				i = 0;
 			}
 			if (i >= HSS1394_MAX_PACKET_SIZE)
 				i = 1;
 		} else if (byte == 0xf7) {
 			if (scs->output_escaped) {
 				if (i >= 1 && scs->output_escape_high_nibble &&
 				    scs->buffer[0] != HSS1394_TAG_CHANGE_ADDRESS)
 					break;
 			} else {
 				if (i > 1 && scs->output_status == 0xf0) {
 					scs->buffer[i++] = 0xf7;
 					break;
 				}
 			}
 			i = 1;
 			scs->output_escaped = false;
 		} else if (!is_invalid_cmd(byte) &&
 			   byte < 0xf8) {
 			i = 1;
 			scs->buffer[0] = HSS1394_TAG_USER_DATA;
 			scs->buffer[i++] = byte;
 			scs->output_status = byte;
 			scs->output_escaped = false;
 			if (is_one_byte_cmd(byte))
 				break;
 		}
 	}
 	scs->output_bytes = 1;
 	scs->output_escaped = false;

 	scs->transaction_running = true;
 	dev = fw_parent_device(scs->unit);
 	generation = dev->generation;
 	smp_rmb(); /* node_id vs. generation */
 	fw_send_request(dev->card, &scs->transaction, TCODE_WRITE_BLOCK_REQUEST,
 			dev->node_id, generation, dev->max_speed,
 			HSS1394_ADDRESS, scs->buffer, i,
 			scs_write_callback, scs);
 }

 static void scs_output_drain(struct snd_rawmidi_substream *stream)
 {
 	struct scs *scs = stream->rmidi->private_data;

 	wait_event(scs->idle_wait, scs->output_idle);
 }

 static struct snd_rawmidi_ops output_ops = {
 	.open    = scs_output_open,
 	.close   = scs_output_close,
 	.trigger = scs_output_trigger,
 	.drain   = scs_output_drain,
 };

 static int scs_input_open(struct snd_rawmidi_substream *stream)
 {
 	struct scs *scs = stream->rmidi->private_data;

 	scs->input_escape_count = 0;

 	return 0;
 }

 static int scs_input_close(struct snd_rawmidi_substream *stream)
 {
 	return 0;
 }

 static void scs_input_trigger(struct snd_rawmidi_substream *stream, int up)
 {
 	struct scs *scs = stream->rmidi->private_data;

 	ACCESS_ONCE(scs->input) = up ? stream : NULL;
 }

 static void scs_input_escaped_byte(struct snd_rawmidi_substream *stream,
 				   u8 byte)
 {
 	u8 nibbles[2];

 	nibbles[0] = byte >> 4;
 	nibbles[1] = byte & 0x0f;
 	snd_rawmidi_receive(stream, nibbles, 2);
 }

 static void scs_input_midi_byte(struct scs *scs,
 				struct snd_rawmidi_substream *stream,
 				u8 byte)
 {
 	if (scs->input_escape_count > 0) {
 		scs_input_escaped_byte(stream, byte);
 		scs->input_escape_count--;
 		if (scs->input_escape_count == 0)
 			snd_rawmidi_receive(stream, (const u8[]) { 0xf7 }, 1);
 	} else if (byte == 0xf9) {
 		snd_rawmidi_receive(stream, sysex_escape_prefix,
 				    ARRAY_SIZE(sysex_escape_prefix));
 		scs_input_escaped_byte(stream, 0x00);
 		scs_input_escaped_byte(stream, 0xf9);
 		scs->input_escape_count = 3;
 	} else {
 		snd_rawmidi_receive(stream, &byte, 1);
 	}
 }

 static void scs_input_packet(struct scs *scs,
 			     struct snd_rawmidi_substream *stream,
 			     const u8 *data, unsigned int bytes)
 {
 	unsigned int i;

 	if (data[0] == HSS1394_TAG_USER_DATA) {
 		for (i = 1; i < bytes; ++i)
 			scs_input_midi_byte(scs, stream, data[i]);
 	} else {
 		snd_rawmidi_receive(stream, sysex_escape_prefix,
 				    ARRAY_SIZE(sysex_escape_prefix));
 		for (i = 0; i < bytes; ++i)
 			scs_input_escaped_byte(stream, data[i]);
 		snd_rawmidi_receive(stream, (const u8[]) { 0xf7 }, 1);
 	}
 }

 static struct snd_rawmidi_ops input_ops = {
 	.open    = scs_input_open,
 	.close   = scs_input_close,
 	.trigger = scs_input_trigger,
 };

 static int scs_create_midi(struct scs *scs)
 {
 	struct snd_rawmidi *rmidi;
 	int err;

 	err = snd_rawmidi_new(scs->card, "SCS.1x", 0, 1, 1, &rmidi);
 	if (err < 0)
 		return err;
 	snprintf(rmidi->name, sizeof(rmidi->name),
 		 "%s MIDI", scs->card->shortname);
 	rmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
 	                    SNDRV_RAWMIDI_INFO_INPUT |
 	                    SNDRV_RAWMIDI_INFO_DUPLEX;
 	rmidi->private_data = scs;
 	snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &output_ops);
 	snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT, &input_ops);

 	return 0;
 }

 static void handle_hss(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 scs *scs = callback_data;
 	struct snd_rawmidi_substream *stream;

 	if (offset != scs->hss_handler.offset) {
 		fw_send_response(card, request, RCODE_ADDRESS_ERROR);
 		return;
 	}
 	if (tcode != TCODE_WRITE_QUADLET_REQUEST &&
 	    tcode != TCODE_WRITE_BLOCK_REQUEST) {
 		fw_send_response(card, request, RCODE_TYPE_ERROR);
 		return;
 	}

 	if (length >= 1) {
 		stream = ACCESS_ONCE(scs->input);
 		if (stream)
 			scs_input_packet(scs, stream, data, length);
 	}

 	fw_send_response(card, request, RCODE_COMPLETE);
 }

 static int scs_init_hss_address(struct scs *scs)
 {
 	__be64 data;
 	int err;

 	data = cpu_to_be64(((u64)HSS1394_TAG_CHANGE_ADDRESS << 56) |
 			   scs->hss_handler.offset);
 	err = snd_fw_transaction(scs->unit, TCODE_WRITE_BLOCK_REQUEST,
 				 HSS1394_ADDRESS, &data, 8);
 	if (err < 0)
 		dev_err(&scs->unit->device, "HSS1394 communication failed\n");

 	return err;
 }

 static void scs_card_free(struct snd_card *card)
 {
 	struct scs *scs = card->private_data;

 	fw_core_remove_address_handler(&scs->hss_handler);
 	kfree(scs->buffer);
 }

 static int scs_probe(struct fw_unit *unit, const struct ieee1394_device_id *id)
 {
 	struct fw_device *fw_dev = fw_parent_device(unit);
 	struct snd_card *card;
 	struct scs *scs;
 	int err;

 	err = snd_card_create(-16, NULL, THIS_MODULE, sizeof(*scs), &card);
 	if (err < 0)
 		return err;
 	snd_card_set_dev(card, &unit->device);

 	scs = card->private_data;
 	scs->card = card;
 	scs->unit = unit;
 	tasklet_init(&scs->tasklet, scs_output_tasklet, (unsigned long)scs);
 	init_waitqueue_head(&scs->idle_wait);
 	scs->output_idle = true;

 	scs->buffer = kmalloc(HSS1394_MAX_PACKET_SIZE, GFP_KERNEL);
 	if (!scs->buffer) {
 		err = -ENOMEM;
 		goto err_card;
 	}

 	scs->hss_handler.length = HSS1394_MAX_PACKET_SIZE;
 	scs->hss_handler.address_callback = handle_hss;
 	scs->hss_handler.callback_data = scs;
 	err = fw_core_add_address_handler(&scs->hss_handler,
 					  &fw_high_memory_region);
 	if (err < 0)
 		goto err_buffer;

 	card->private_free = scs_card_free;

 	strcpy(card->driver, "SCS.1x");
 	strcpy(card->shortname, "SCS.1x");
 	fw_csr_string(unit->directory, CSR_MODEL,
 		      card->shortname, sizeof(card->shortname));
 	snprintf(card->longname, sizeof(card->longname),
 		 "Stanton DJ %s (GUID %08x%08x) at %s, S%d",
 		 card->shortname, fw_dev->config_rom[3], fw_dev->config_rom[4],
 		 dev_name(&unit->device), 100 << fw_dev->max_speed);
 	strcpy(card->mixername, card->shortname);

 	err = scs_init_hss_address(scs);
 	if (err < 0)
 		goto err_card;

 	err = scs_create_midi(scs);
 	if (err < 0)
 		goto err_card;

 	err = snd_card_register(card);
 	if (err < 0)
 		goto err_card;

 	dev_set_drvdata(&unit->device, scs);

 	return 0;

 err_buffer:
 	kfree(scs->buffer);
 err_card:
 	snd_card_free(card);
 	return err;
 }

 static void scs_update(struct fw_unit *unit)
 {
 	struct scs *scs = dev_get_drvdata(&unit->device);
 	__be64 data;

 	data = cpu_to_be64(((u64)HSS1394_TAG_CHANGE_ADDRESS << 56) |
 			   scs->hss_handler.offset);
 	snd_fw_transaction(scs->unit, TCODE_WRITE_BLOCK_REQUEST,
 			   HSS1394_ADDRESS, &data, 8);
 }

 static void scs_remove(struct fw_unit *unit)
 {
 	struct scs *scs = dev_get_drvdata(&unit->device);

 	snd_card_disconnect(scs->card);

 	ACCESS_ONCE(scs->output) = NULL;
 	ACCESS_ONCE(scs->input) = NULL;

 	wait_event(scs->idle_wait, scs->output_idle);

 	tasklet_kill(&scs->tasklet);

 	snd_card_free_when_closed(scs->card);
 }

 static const struct ieee1394_device_id scs_id_table[] = {
 	{
 		.match_flags = IEEE1394_MATCH_VENDOR_ID |
 		               IEEE1394_MATCH_MODEL_ID,
 		.vendor_id   = OUI_STANTON,
 		.model_id    = MODEL_SCS_1M,
 	},
 	{
 		.match_flags = IEEE1394_MATCH_VENDOR_ID |
 		               IEEE1394_MATCH_MODEL_ID,
 		.vendor_id   = OUI_STANTON,
 		.model_id    = MODEL_SCS_1D,
 	},
 	{}
 };
 MODULE_DEVICE_TABLE(ieee1394, scs_id_table);

 MODULE_DESCRIPTION("SCS.1x MIDI driver");
 MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
 MODULE_LICENSE("GPL v2");

 static struct fw_driver scs_driver = {
 	.driver = {
 		.owner  = THIS_MODULE,
 		.name   = KBUILD_MODNAME,
 		.bus    = &fw_bus_type,
 	},
 	.probe    = scs_probe,
 	.update   = scs_update,
 	.remove   = scs_remove,
 	.id_table = scs_id_table,
 };

 static int __init alsa_scs1x_init(void)
 {
 	return driver_register(&scs_driver.driver);
 }

 static void __exit alsa_scs1x_exit(void)
 {
 	driver_unregister(&scs_driver.driver);
 }

 module_init(alsa_scs1x_init);
 module_exit(alsa_scs1x_exit);
	/*
	* Stanton Control System 1 MIDI driver
	*
	* Copyright (c) Clemens Ladisch <clemens@ladisch.de>
	* Licensed under the terms of the GNU General Public License, version 2.
	*/

	#include <linux/device.h>
	#include <linux/firewire.h>
	#include <linux/firewire-constants.h>
	#include <linux/interrupt.h>
	#include <linux/module.h>
	#include <linux/mod_devicetable.h>
	#include <linux/slab.h>
	#include <linux/string.h>
	#include <linux/wait.h>
	#include <sound/core.h>
	#include <sound/initval.h>
	#include <sound/rawmidi.h>
	#include "lib.h"

	#define OUI_STANTON 0x001260
	#define MODEL_SCS_1M 0x001000
	#define MODEL_SCS_1D 0x002000

	#define HSS1394_ADDRESS 0xc007dedadadaULL
	#define HSS1394_MAX_PACKET_SIZE 64

	#define HSS1394_TAG_USER_DATA 0x00
	#define HSS1394_TAG_CHANGE_ADDRESS 0xf1

	struct scs {
	struct snd_card *card;
	struct fw_unit *unit;
	struct fw_address_handler hss_handler;
	struct fw_transaction transaction;
	bool transaction_running;
	bool output_idle;
	u8 output_status;
	u8 output_bytes;
	bool output_escaped;
	bool output_escape_high_nibble;
	u8 input_escape_count;
	struct snd_rawmidi_substream *output;
	struct snd_rawmidi_substream *input;
	struct tasklet_struct tasklet;
	wait_queue_head_t idle_wait;
	u8 *buffer;
	};

	static const u8 sysex_escape_prefix[] = {
	0xf0, /* SysEx begin */
	0x00, 0x01, 0x60, /* Stanton DJ */
	0x48, 0x53, 0x53, /* "HSS" */
	};

	static int scs_output_open(struct snd_rawmidi_substream *stream)
	{
	struct scs *scs = stream->rmidi->private_data;

	scs->output_status = 0;
	scs->output_bytes = 1;
	scs->output_escaped = false;

	return 0;
	}

	static int scs_output_close(struct snd_rawmidi_substream *stream)
	{
	return 0;
	}

	static void scs_output_trigger(struct snd_rawmidi_substream *stream, int up)
	{
	struct scs *scs = stream->rmidi->private_data;

	ACCESS_ONCE(scs->output) = up ? stream : NULL;
	if (up) {
	scs->output_idle = false;
	tasklet_schedule(&scs->tasklet);
	}
	}

	static void scs_write_callback(struct fw_card *card, int rcode,
	void data, size_t length, void callback_data)
	{
	struct scs *scs = callback_data;

	if (rcode == RCODE_GENERATION) {
	/* TODO: retry this packet */
	}

	scs->transaction_running = false;
	tasklet_schedule(&scs->tasklet);
	}

	static bool is_valid_running_status(u8 status)
	{
	return status >= 0x80 && status <= 0xef;
	}

	static bool is_one_byte_cmd(u8 status)
	{
	return status == 0xf6 \|\|
	status >= 0xf8;
	}

	static bool is_two_bytes_cmd(u8 status)
	{
	return (status >= 0xc0 && status <= 0xdf) \|\|
	status == 0xf1 \|\|
	status == 0xf3;
	}

	static bool is_three_bytes_cmd(u8 status)
	{
	return (status >= 0x80 && status <= 0xbf) \|\|
	(status >= 0xe0 && status <= 0xef) \|\|
	status == 0xf2;
	}

	static bool is_invalid_cmd(u8 status)
	{
	return status == 0xf4 \|\|
	status == 0xf5 \|\|
	status == 0xf9 \|\|
	status == 0xfd;
	}

	static void scs_output_tasklet(unsigned long data)
	{
	struct scs scs = (void )data;
	struct snd_rawmidi_substream *stream;
	unsigned int i;
	u8 byte;
	struct fw_device *dev;
	int generation;

	if (scs->transaction_running)
	return;

	stream = ACCESS_ONCE(scs->output);
	if (!stream) {
	scs->output_idle = true;
	wake_up(&scs->idle_wait);
	return;
	}

	i = scs->output_bytes;
	for (;;) {
	if (snd_rawmidi_transmit(stream, &byte, 1) != 1) {
	scs->output_bytes = i;
	scs->output_idle = true;
	wake_up(&scs->idle_wait);
	return;
	}
	/*
	* Convert from real MIDI to what I think the device expects (no
	* running status, one command per packet, unescaped SysExs).
	*/
	if (scs->output_escaped && byte < 0x80) {
	if (scs->output_escape_high_nibble) {
	if (i < HSS1394_MAX_PACKET_SIZE) {
	scs->buffer[i] = byte << 4;
	scs->output_escape_high_nibble = false;
	}
	} else {
	scs->buffer[i++] \|= byte & 0x0f;
	scs->output_escape_high_nibble = true;
	}
	} else if (byte < 0x80) {
	if (i == 1) {
	if (!is_valid_running_status(scs->output_status))
	continue;
	scs->buffer[0] = HSS1394_TAG_USER_DATA;
	scs->buffer[i++] = scs->output_status;
	}
	scs->buffer[i++] = byte;
	if ((i == 3 && is_two_bytes_cmd(scs->output_status)) \|\|
	(i == 4 && is_three_bytes_cmd(scs->output_status)))
	break;
	if (i == 1 + ARRAY_SIZE(sysex_escape_prefix) &&
	!memcmp(scs->buffer + 1, sysex_escape_prefix,
	ARRAY_SIZE(sysex_escape_prefix))) {
	scs->output_escaped = true;
	scs->output_escape_high_nibble = true;
	i = 0;
	}
	if (i >= HSS1394_MAX_PACKET_SIZE)
	i = 1;
	} else if (byte == 0xf7) {
	if (scs->output_escaped) {
	if (i >= 1 && scs->output_escape_high_nibble &&
	scs->buffer[0] != HSS1394_TAG_CHANGE_ADDRESS)
	break;
	} else {
	if (i > 1 && scs->output_status == 0xf0) {
	scs->buffer[i++] = 0xf7;
	break;
	}
	}
	i = 1;
	scs->output_escaped = false;
	} else if (!is_invalid_cmd(byte) &&
	byte < 0xf8) {
	i = 1;
	scs->buffer[0] = HSS1394_TAG_USER_DATA;
	scs->buffer[i++] = byte;
	scs->output_status = byte;
	scs->output_escaped = false;
	if (is_one_byte_cmd(byte))
	break;
	}
	}
	scs->output_bytes = 1;
	scs->output_escaped = false;

	scs->transaction_running = true;
	dev = fw_parent_device(scs->unit);
	generation = dev->generation;
	smp_rmb(); /* node_id vs. generation */
	fw_send_request(dev->card, &scs->transaction, TCODE_WRITE_BLOCK_REQUEST,
	dev->node_id, generation, dev->max_speed,
	HSS1394_ADDRESS, scs->buffer, i,
	scs_write_callback, scs);
	}

	static void scs_output_drain(struct snd_rawmidi_substream *stream)
	{
	struct scs *scs = stream->rmidi->private_data;

	wait_event(scs->idle_wait, scs->output_idle);
	}

	static struct snd_rawmidi_ops output_ops = {
	.open = scs_output_open,
	.close = scs_output_close,
	.trigger = scs_output_trigger,
	.drain = scs_output_drain,
	};

	static int scs_input_open(struct snd_rawmidi_substream *stream)
	{
	struct scs *scs = stream->rmidi->private_data;

	scs->input_escape_count = 0;

	return 0;
	}

	static int scs_input_close(struct snd_rawmidi_substream *stream)
	{
	return 0;
	}

	static void scs_input_trigger(struct snd_rawmidi_substream *stream, int up)
	{
	struct scs *scs = stream->rmidi->private_data;

	ACCESS_ONCE(scs->input) = up ? stream : NULL;
	}

	static void scs_input_escaped_byte(struct snd_rawmidi_substream *stream,
	u8 byte)
	{
	u8 nibbles[2];

	nibbles[0] = byte >> 4;
	nibbles[1] = byte & 0x0f;
	snd_rawmidi_receive(stream, nibbles, 2);
	}

	static void scs_input_midi_byte(struct scs *scs,
	struct snd_rawmidi_substream *stream,
	u8 byte)
	{
	if (scs->input_escape_count > 0) {
	scs_input_escaped_byte(stream, byte);
	scs->input_escape_count--;
	if (scs->input_escape_count == 0)
	snd_rawmidi_receive(stream, (const u8[]) { 0xf7 }, 1);
	} else if (byte == 0xf9) {
	snd_rawmidi_receive(stream, sysex_escape_prefix,
	ARRAY_SIZE(sysex_escape_prefix));
	scs_input_escaped_byte(stream, 0x00);
	scs_input_escaped_byte(stream, 0xf9);
	scs->input_escape_count = 3;
	} else {
	snd_rawmidi_receive(stream, &byte, 1);
	}
	}

	static void scs_input_packet(struct scs *scs,
	struct snd_rawmidi_substream *stream,
	const u8 *data, unsigned int bytes)
	{
	unsigned int i;

	if (data[0] == HSS1394_TAG_USER_DATA) {
	for (i = 1; i < bytes; ++i)
	scs_input_midi_byte(scs, stream, data[i]);
	} else {
	snd_rawmidi_receive(stream, sysex_escape_prefix,
	ARRAY_SIZE(sysex_escape_prefix));
	for (i = 0; i < bytes; ++i)
	scs_input_escaped_byte(stream, data[i]);
	snd_rawmidi_receive(stream, (const u8[]) { 0xf7 }, 1);
	}
	}

	static struct snd_rawmidi_ops input_ops = {
	.open = scs_input_open,
	.close = scs_input_close,
	.trigger = scs_input_trigger,
	};

	static int scs_create_midi(struct scs *scs)
	{
	struct snd_rawmidi *rmidi;
	int err;

	err = snd_rawmidi_new(scs->card, "SCS.1x", 0, 1, 1, &rmidi);
	if (err < 0)
	return err;
	snprintf(rmidi->name, sizeof(rmidi->name),
	"%s MIDI", scs->card->shortname);
	rmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT \|
	SNDRV_RAWMIDI_INFO_INPUT \|
	SNDRV_RAWMIDI_INFO_DUPLEX;
	rmidi->private_data = scs;
	snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &output_ops);
	snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT, &input_ops);

	return 0;
	}

	static void handle_hss(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 scs *scs = callback_data;
	struct snd_rawmidi_substream *stream;

	if (offset != scs->hss_handler.offset) {
	fw_send_response(card, request, RCODE_ADDRESS_ERROR);
	return;
	}
	if (tcode != TCODE_WRITE_QUADLET_REQUEST &&
	tcode != TCODE_WRITE_BLOCK_REQUEST) {
	fw_send_response(card, request, RCODE_TYPE_ERROR);
	return;
	}

	if (length >= 1) {
	stream = ACCESS_ONCE(scs->input);
	if (stream)
	scs_input_packet(scs, stream, data, length);
	}

	fw_send_response(card, request, RCODE_COMPLETE);
	}

	static int scs_init_hss_address(struct scs *scs)
	{
	__be64 data;
	int err;

	data = cpu_to_be64(((u64)HSS1394_TAG_CHANGE_ADDRESS << 56) \|
	scs->hss_handler.offset);
	err = snd_fw_transaction(scs->unit, TCODE_WRITE_BLOCK_REQUEST,
	HSS1394_ADDRESS, &data, 8);
	if (err < 0)
	dev_err(&scs->unit->device, "HSS1394 communication failed\n");

	return err;
	}

	static void scs_card_free(struct snd_card *card)
	{
	struct scs *scs = card->private_data;

	fw_core_remove_address_handler(&scs->hss_handler);
	kfree(scs->buffer);
	}

	static int scs_probe(struct fw_unit unit, const struct ieee1394_device_id id)
	{
	struct fw_device *fw_dev = fw_parent_device(unit);
	struct snd_card *card;
	struct scs *scs;
	int err;

	err = snd_card_create(-16, NULL, THIS_MODULE, sizeof(*scs), &card);
	if (err < 0)
	return err;
	snd_card_set_dev(card, &unit->device);

	scs = card->private_data;
	scs->card = card;
	scs->unit = unit;
	tasklet_init(&scs->tasklet, scs_output_tasklet, (unsigned long)scs);
	init_waitqueue_head(&scs->idle_wait);
	scs->output_idle = true;

	scs->buffer = kmalloc(HSS1394_MAX_PACKET_SIZE, GFP_KERNEL);
	if (!scs->buffer) {
	err = -ENOMEM;
	goto err_card;
	}

	scs->hss_handler.length = HSS1394_MAX_PACKET_SIZE;
	scs->hss_handler.address_callback = handle_hss;
	scs->hss_handler.callback_data = scs;
	err = fw_core_add_address_handler(&scs->hss_handler,
	&fw_high_memory_region);
	if (err < 0)
	goto err_buffer;

	card->private_free = scs_card_free;

	strcpy(card->driver, "SCS.1x");
	strcpy(card->shortname, "SCS.1x");
	fw_csr_string(unit->directory, CSR_MODEL,
	card->shortname, sizeof(card->shortname));
	snprintf(card->longname, sizeof(card->longname),
	"Stanton DJ %s (GUID %08x%08x) at %s, S%d",
	card->shortname, fw_dev->config_rom[3], fw_dev->config_rom[4],
	dev_name(&unit->device), 100 << fw_dev->max_speed);
	strcpy(card->mixername, card->shortname);

	err = scs_init_hss_address(scs);
	if (err < 0)
	goto err_card;

	err = scs_create_midi(scs);
	if (err < 0)
	goto err_card;

	err = snd_card_register(card);
	if (err < 0)
	goto err_card;

	dev_set_drvdata(&unit->device, scs);

	return 0;

	err_buffer:
	kfree(scs->buffer);
	err_card:
	snd_card_free(card);
	return err;
	}

	static void scs_update(struct fw_unit *unit)
	{
	struct scs *scs = dev_get_drvdata(&unit->device);
	__be64 data;

	data = cpu_to_be64(((u64)HSS1394_TAG_CHANGE_ADDRESS << 56) \|
	scs->hss_handler.offset);
	snd_fw_transaction(scs->unit, TCODE_WRITE_BLOCK_REQUEST,
	HSS1394_ADDRESS, &data, 8);
	}

	static void scs_remove(struct fw_unit *unit)
	{
	struct scs *scs = dev_get_drvdata(&unit->device);

	snd_card_disconnect(scs->card);

	ACCESS_ONCE(scs->output) = NULL;
	ACCESS_ONCE(scs->input) = NULL;

	wait_event(scs->idle_wait, scs->output_idle);

	tasklet_kill(&scs->tasklet);

	snd_card_free_when_closed(scs->card);
	}

	static const struct ieee1394_device_id scs_id_table[] = {
	{
	.match_flags = IEEE1394_MATCH_VENDOR_ID \|
	IEEE1394_MATCH_MODEL_ID,
	.vendor_id = OUI_STANTON,
	.model_id = MODEL_SCS_1M,
	},
	{
	.match_flags = IEEE1394_MATCH_VENDOR_ID \|
	IEEE1394_MATCH_MODEL_ID,
	.vendor_id = OUI_STANTON,
	.model_id = MODEL_SCS_1D,
	},
	{}
	};
	MODULE_DEVICE_TABLE(ieee1394, scs_id_table);

	MODULE_DESCRIPTION("SCS.1x MIDI driver");
	MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
	MODULE_LICENSE("GPL v2");

	static struct fw_driver scs_driver = {
	.driver = {
	.owner = THIS_MODULE,
	.name = KBUILD_MODNAME,
	.bus = &fw_bus_type,
	},
	.probe = scs_probe,
	.update = scs_update,
	.remove = scs_remove,
	.id_table = scs_id_table,
	};

	static int __init alsa_scs1x_init(void)
	{
	return driver_register(&scs_driver.driver);
	}

	static void __exit alsa_scs1x_exit(void)
	{
	driver_unregister(&scs_driver.driver);
	}

	module_init(alsa_scs1x_init);
	module_exit(alsa_scs1x_exit);