/*
 * ff-protocol-ff400.c - a part of driver for RME Fireface series
 *
 * Copyright (c) 2015-2017 Takashi Sakamoto
 *
 * Licensed under the terms of the GNU General Public License, version 2.
 */

#include <linux/delay.h>
#include "ff.h"

#define FF400_STF		0x000080100500ull
#define FF400_RX_PACKET_FORMAT	0x000080100504ull
#define FF400_ISOC_COMM_START	0x000080100508ull
#define FF400_TX_PACKET_FORMAT	0x00008010050cull
#define FF400_ISOC_COMM_STOP	0x000080100510ull

static int ff400_begin_session(struct snd_ff *ff, unsigned int rate)
{
	__le32 reg;
	int i, err;

	/* Check whether the given value is supported or not. */
	for (i = 0; i < CIP_SFC_COUNT; i++) {
		if (amdtp_rate_table[i] == rate)
			break;
	}
	if (i == CIP_SFC_COUNT)
		return -EINVAL;

	/* Set the number of data blocks transferred in a second. */
	reg = cpu_to_le32(rate);
	err = snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
				 FF400_STF, &reg, sizeof(reg), 0);
	if (err < 0)
		return err;

	msleep(100);

	/*
	 * Set isochronous channel and the number of quadlets of received
	 * packets.
	 */
	reg = cpu_to_le32(((ff->rx_stream.data_block_quadlets << 3) << 8) |
			  ff->rx_resources.channel);
	err = snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
				 FF400_RX_PACKET_FORMAT, &reg, sizeof(reg), 0);
	if (err < 0)
		return err;

	/*
	 * Set isochronous channel and the number of quadlets of transmitted
	 * packet.
	 */
	/* TODO: investigate the purpose of this 0x80. */
	reg = cpu_to_le32((0x80 << 24) |
			  (ff->tx_resources.channel << 5) |
			  (ff->tx_stream.data_block_quadlets));
	err = snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
				 FF400_TX_PACKET_FORMAT, &reg, sizeof(reg), 0);
	if (err < 0)
		return err;

	/* Allow to transmit packets. */
	reg = cpu_to_le32(0x00000001);
	return snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
				 FF400_ISOC_COMM_START, &reg, sizeof(reg), 0);
}

static void ff400_finish_session(struct snd_ff *ff)
{
	__le32 reg;

	reg = cpu_to_le32(0x80000000);
	snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
			   FF400_ISOC_COMM_STOP, &reg, sizeof(reg), 0);
}

static int ff400_switch_fetching_mode(struct snd_ff *ff, bool enable)
{
	__le32 *reg;
	int i;
	int err;

	reg = kcalloc(18, sizeof(__le32), GFP_KERNEL);
	if (reg == NULL)
		return -ENOMEM;

	if (!enable) {
		/*
		 * Each quadlet is corresponding to data channels in a data
		 * blocks in reverse order. Precisely, quadlets for available
		 * data channels should be enabled. Here, I take second best
		 * to fetch PCM frames from all of data channels regardless of
		 * stf.
		 */
		for (i = 0; i < 18; ++i)
			reg[i] = cpu_to_le32(0x00000001);
	}

	err = snd_fw_transaction(ff->unit, TCODE_WRITE_BLOCK_REQUEST,
				 SND_FF_REG_FETCH_PCM_FRAMES, reg,
				 sizeof(__le32) * 18, 0);
	kfree(reg);
	return err;
}

static void ff400_handle_midi_msg(struct snd_ff *ff, __le32 *buf, size_t length)
{
	int i;

	for (i = 0; i < length / 4; i++) {
		u32 quad = le32_to_cpu(buf[i]);
		u8 byte;
		unsigned int index;
		struct snd_rawmidi_substream *substream;

		/* Message in first port. */
		/*
		 * This value may represent the index of this unit when the same
		 * units are on the same IEEE 1394 bus. This driver doesn't use
		 * it.
		 */
		index = (quad >> 8) & 0xff;
		if (index > 0) {
			substream = READ_ONCE(ff->tx_midi_substreams[0]);
			if (substream != NULL) {
				byte = quad & 0xff;
				snd_rawmidi_receive(substream, &byte, 1);
			}
		}

		/* Message in second port. */
		index = (quad >> 24) & 0xff;
		if (index > 0) {
			substream = READ_ONCE(ff->tx_midi_substreams[1]);
			if (substream != NULL) {
				byte = (quad >> 16) & 0xff;
				snd_rawmidi_receive(substream, &byte, 1);
			}
		}
	}
}

const struct snd_ff_protocol snd_ff_protocol_ff400 = {
	.handle_midi_msg	= ff400_handle_midi_msg,
	.begin_session		= ff400_begin_session,
	.finish_session		= ff400_finish_session,
	.switch_fetching_mode	= ff400_switch_fetching_mode,
};