// SPDX-License-Identifier: GPL-2.0-only
/*
 * ff-transaction.c - a part of driver for RME Fireface series
 *
 * Copyright (c) 2015-2017 Takashi Sakamoto
 */

#include "ff.h"

static void finish_transmit_midi_msg(struct snd_ff *ff, unsigned int port,
                                     int rcode)
{
        struct snd_rawmidi_substream *substream =
                                READ_ONCE(ff->rx_midi_substreams[port]);

        if (rcode_is_permanent_error(rcode)) {
                ff->rx_midi_error[port] = true;
                return;
        }

        if (rcode != RCODE_COMPLETE) {
                /* Transfer the message again, immediately. */
                ff->next_ktime[port] = 0;
                schedule_work(&ff->rx_midi_work[port]);
                return;
        }

        snd_rawmidi_transmit_ack(substream, ff->rx_bytes[port]);
        ff->rx_bytes[port] = 0;

        if (!snd_rawmidi_transmit_empty(substream))
                schedule_work(&ff->rx_midi_work[port]);
}

static void finish_transmit_midi0_msg(struct fw_card *card, int rcode,
                                      void *data, size_t length,
                                      void *callback_data)
{
        struct snd_ff *ff =
                container_of(callback_data, struct snd_ff, transactions[0]);
        finish_transmit_midi_msg(ff, 0, rcode);
}

static void finish_transmit_midi1_msg(struct fw_card *card, int rcode,
                                      void *data, size_t length,
                                      void *callback_data)
{
        struct snd_ff *ff =
                container_of(callback_data, struct snd_ff, transactions[1]);
        finish_transmit_midi_msg(ff, 1, rcode);
}

static void transmit_midi_msg(struct snd_ff *ff, unsigned int port)
{
        struct snd_rawmidi_substream *substream =
                        READ_ONCE(ff->rx_midi_substreams[port]);
        int quad_count;

        struct fw_device *fw_dev = fw_parent_device(ff->unit);
        unsigned long long addr;
        int generation;
        fw_transaction_callback_t callback;
        int tcode;

        if (substream == NULL || snd_rawmidi_transmit_empty(substream))
                return;

        if (ff->rx_bytes[port] > 0 || ff->rx_midi_error[port])
                return;

        /* Do it in next chance. */
        if (ktime_after(ff->next_ktime[port], ktime_get())) {
                schedule_work(&ff->rx_midi_work[port]);
                return;
        }

        quad_count = ff->spec->protocol->fill_midi_msg(ff, substream, port);
        if (quad_count <= 0)
                return;

        if (port == 0) {
                addr = ff->spec->midi_rx_addrs[0];
                callback = finish_transmit_midi0_msg;
        } else {
                addr = ff->spec->midi_rx_addrs[1];
                callback = finish_transmit_midi1_msg;
        }

        /* Set interval to next transaction. */
        ff->next_ktime[port] = ktime_add_ns(ktime_get(),
                        ff->rx_bytes[port] * 8 * (NSEC_PER_SEC / 31250));

        if (quad_count == 1)
                tcode = TCODE_WRITE_QUADLET_REQUEST;
        else
                tcode = TCODE_WRITE_BLOCK_REQUEST;

        /*
         * 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 = fw_dev->generation;
        smp_rmb();
        fw_send_request(fw_dev->card, &ff->transactions[port], tcode,
                        fw_dev->node_id, generation, fw_dev->max_speed,
                        addr, &ff->msg_buf[port], quad_count * 4,
                        callback, &ff->transactions[port]);
}

static void transmit_midi0_msg(struct work_struct *work)
{
        struct snd_ff *ff = container_of(work, struct snd_ff, rx_midi_work[0]);

        transmit_midi_msg(ff, 0);
}

static void transmit_midi1_msg(struct work_struct *work)
{
        struct snd_ff *ff = container_of(work, struct snd_ff, rx_midi_work[1]);

        transmit_midi_msg(ff, 1);
}

static void handle_msg(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_ff *ff = callback_data;
        __le32 *buf = data;
        u32 tstamp = fw_request_get_timestamp(request);

        fw_send_response(card, request, RCODE_COMPLETE);

        offset -= ff->async_handler.offset;

        guard(spinlock_irqsave)(&ff->lock);
        ff->spec->protocol->handle_msg(ff, (unsigned int)offset, buf, length, tstamp);
}

static int allocate_own_address(struct snd_ff *ff, int i)
{
        struct fw_address_region midi_msg_region;
        int err;

        ff->async_handler.length = ff->spec->midi_addr_range;
        ff->async_handler.address_callback = handle_msg;
        ff->async_handler.callback_data = ff;

        midi_msg_region.start = 0x000100000000ull * i;
        midi_msg_region.end = midi_msg_region.start + ff->async_handler.length;

        err = fw_core_add_address_handler(&ff->async_handler, &midi_msg_region);
        if (err >= 0) {
                /* Controllers are allowed to register this region. */
                if (ff->async_handler.offset & 0x0000ffffffff) {
                        fw_core_remove_address_handler(&ff->async_handler);
                        err = -EAGAIN;
                }
        }

        return err;
}

// Controllers are allowed to register higher 4 bytes of destination address to
// receive asynchronous transactions for MIDI messages, while the way to
// register lower 4 bytes of address is different depending on protocols. For
// details, please refer to comments in protocol implementations.
//
// This driver expects userspace applications to configure registers for the
// lower address because in most cases such registers has the other settings.
int snd_ff_transaction_reregister(struct snd_ff *ff)
{
        struct fw_card *fw_card = fw_parent_device(ff->unit)->card;
        u32 addr;
        __le32 reg;

        /*
         * Controllers are allowed to register its node ID and upper 2 byte of
         * local address to listen asynchronous transactions.
         */
        addr = (fw_card->node_id << 16) | (ff->async_handler.offset >> 32);
        reg = cpu_to_le32(addr);
        return snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
                                  ff->spec->midi_high_addr,
                                  &reg, sizeof(reg), 0);
}

int snd_ff_transaction_register(struct snd_ff *ff)
{
        int i, err;

        /*
         * Allocate in Memory Space of IEC 13213, but lower 4 byte in LSB should
         * be zero due to device specification.
         */
        for (i = 0; i < 0xffff; i++) {
                err = allocate_own_address(ff, i);
                if (err != -EBUSY && err != -EAGAIN)
                        break;
        }
        if (err < 0)
                return err;

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

        INIT_WORK(&ff->rx_midi_work[0], transmit_midi0_msg);
        INIT_WORK(&ff->rx_midi_work[1], transmit_midi1_msg);

        return 0;
}

void snd_ff_transaction_unregister(struct snd_ff *ff)
{
        __le32 reg;

        if (ff->async_handler.callback_data == NULL)
                return;
        ff->async_handler.callback_data = NULL;

        /* Release higher 4 bytes of address. */
        reg = cpu_to_le32(0x00000000);
        snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
                           ff->spec->midi_high_addr,
                           &reg, sizeof(reg), 0);

        fw_core_remove_address_handler(&ff->async_handler);
}