/*
 * 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 device *unit_dev)
{
	struct fw_unit *unit = fw_unit(unit_dev);
	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_dev);

	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)
		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_dev, scs);

	return 0;

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

static int scs_remove(struct device *dev)
{
	struct scs *scs = dev_get_drvdata(dev);

	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);

	return 0;
}

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 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,
		.remove = scs_remove,
	},
	.update   = scs_update,
	.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);
