/*
 * 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;
}