/*
 * ff-protocol-ff800.c - a part of driver for RME Fireface series
 *
 * Copyright (c) 2018 Takashi Sakamoto
 *
 * Licensed under the terms of the GNU General Public License, version 2.
 */

#include <linux/delay.h>

#include "ff.h"

#define FF800_STF		0x0000fc88f000
#define FF800_RX_PACKET_FORMAT	0x0000fc88f004
#define FF800_ALLOC_TX_STREAM	0x0000fc88f008
#define FF800_ISOC_COMM_START	0x0000fc88f00c
#define   FF800_TX_S800_FLAG	0x00000800
#define FF800_ISOC_COMM_STOP	0x0000fc88f010

#define FF800_TX_PACKET_ISOC_CH	0x0000801c0008

static int allocate_rx_resources(struct snd_ff *ff)
{
	u32 data;
	__le32 reg;
	int err;

	// Controllers should allocate isochronous resources for rx stream.
	err = fw_iso_resources_allocate(&ff->rx_resources,
				amdtp_stream_get_max_payload(&ff->rx_stream),
				fw_parent_device(ff->unit)->max_speed);
	if (err < 0)
		return err;

	// Set isochronous channel and the number of quadlets of rx packets.
	data = ff->rx_stream.data_block_quadlets << 3;
	data = (data << 8) | ff->rx_resources.channel;
	reg = cpu_to_le32(data);
	return snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
				FF800_RX_PACKET_FORMAT, &reg, sizeof(reg), 0);
}

static int allocate_tx_resources(struct snd_ff *ff)
{
	__le32 reg;
	unsigned int count;
	unsigned int tx_isoc_channel;
	int err;

	reg = cpu_to_le32(ff->tx_stream.data_block_quadlets);
	err = snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
				 FF800_ALLOC_TX_STREAM, &reg, sizeof(reg), 0);
	if (err < 0)
		return err;

	// Wait till the format of tx packet is available.
	count = 0;
	while (count++ < 10) {
		u32 data;
		err = snd_fw_transaction(ff->unit, TCODE_READ_QUADLET_REQUEST,
				FF800_TX_PACKET_ISOC_CH, &reg, sizeof(reg), 0);
		if (err < 0)
			return err;

		data = le32_to_cpu(reg);
		if (data != 0xffffffff) {
			tx_isoc_channel = data;
			break;
		}

		msleep(50);
	}
	if (count >= 10)
		return -ETIMEDOUT;

	// NOTE: this is a makeshift to start OHCI 1394 IR context in the
	// channel. On the other hand, 'struct fw_iso_resources.allocated' is
	// not true and it's not deallocated at stop.
	ff->tx_resources.channel = tx_isoc_channel;

	return 0;
}

static int ff800_begin_session(struct snd_ff *ff, unsigned int rate)
{
	__le32 reg;
	int err;

	reg = cpu_to_le32(rate);
	err = snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
				 FF800_STF, &reg, sizeof(reg), 0);
	if (err < 0)
		return err;

	// If starting isochronous communication immediately, change of STF has
	// no effect. In this case, the communication runs based on former STF.
	// Let's sleep for a bit.
	msleep(100);

	err = allocate_rx_resources(ff);
	if (err < 0)
		return err;

	err = allocate_tx_resources(ff);
	if (err < 0)
		return err;

	reg = cpu_to_le32(0x80000000);
	reg |= cpu_to_le32(ff->tx_stream.data_block_quadlets);
	if (fw_parent_device(ff->unit)->max_speed == SCODE_800)
		reg |= cpu_to_le32(FF800_TX_S800_FLAG);
	return snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
				 FF800_ISOC_COMM_START, &reg, sizeof(reg), 0);
}

static void ff800_finish_session(struct snd_ff *ff)
{
	__le32 reg;

	reg = cpu_to_le32(0x80000000);
	snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
			   FF800_ISOC_COMM_STOP, &reg, sizeof(reg), 0);
}

static void ff800_handle_midi_msg(struct snd_ff *ff, __le32 *buf, size_t length)
{
	int i;

	for (i = 0; i < length / 4; i++) {
		u8 byte = le32_to_cpu(buf[i]) & 0xff;
		struct snd_rawmidi_substream *substream;

		substream = READ_ONCE(ff->tx_midi_substreams[0]);
		if (substream)
			snd_rawmidi_receive(substream, &byte, 1);
	}
}

const struct snd_ff_protocol snd_ff_protocol_ff800 = {
	.handle_midi_msg	= ff800_handle_midi_msg,
	.begin_session		= ff800_begin_session,
	.finish_session		= ff800_finish_session,
};