// SPDX-License-Identifier: GPL-2.0-only
/*
 * Line 6 Linux USB driver
 *
 * Copyright (C) 2004-2010 Markus Grabner (line6@grabner-graz.at)
 */

#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/export.h>
#include <sound/core.h>
#include <sound/rawmidi.h>

#include "driver.h"
#include "midi.h"

#define line6_rawmidi_substream_midi(substream) \
        ((struct snd_line6_midi *)((substream)->rmidi->private_data))

static int send_midi_async(struct usb_line6 *line6, unsigned char *data,
                           int length);

/*
        Pass data received via USB to MIDI.
*/
void line6_midi_receive(struct usb_line6 *line6, unsigned char *data,
                        int length)
{
        if (line6->line6midi->substream_receive)
                snd_rawmidi_receive(line6->line6midi->substream_receive,
                                    data, length);
}

/*
        Read data from MIDI buffer and transmit them via USB.
*/
static void line6_midi_transmit(struct snd_rawmidi_substream *substream)
{
        struct usb_line6 *line6 =
            line6_rawmidi_substream_midi(substream)->line6;
        struct snd_line6_midi *line6midi = line6->line6midi;
        struct midi_buffer *mb = &line6midi->midibuf_out;
        unsigned char chunk[LINE6_FALLBACK_MAXPACKETSIZE];
        int req, done;

        for (;;) {
                req = min3(line6_midibuf_bytes_free(mb), line6->max_packet_size,
                           LINE6_FALLBACK_MAXPACKETSIZE);
                done = snd_rawmidi_transmit_peek(substream, chunk, req);

                if (done == 0)
                        break;

                line6_midibuf_write(mb, chunk, done);
                snd_rawmidi_transmit_ack(substream, done);
        }

        for (;;) {
                done = line6_midibuf_read(mb, chunk,
                                          LINE6_FALLBACK_MAXPACKETSIZE,
                                          LINE6_MIDIBUF_READ_TX);

                if (done == 0)
                        break;

                send_midi_async(line6, chunk, done);
        }
}

/*
        Notification of completion of MIDI transmission.
*/
static void midi_sent(struct urb *urb)
{
        int status;
        int num;
        struct usb_line6 *line6 = (struct usb_line6 *)urb->context;

        status = urb->status;
        kfree(urb->transfer_buffer);
        usb_free_urb(urb);

        if (status == -ESHUTDOWN)
                return;

        guard(spinlock_irqsave)(&line6->line6midi->lock);
        num = --line6->line6midi->num_active_send_urbs;

        if (num == 0) {
                line6_midi_transmit(line6->line6midi->substream_transmit);
                num = line6->line6midi->num_active_send_urbs;
        }

        if (num == 0)
                wake_up(&line6->line6midi->send_wait);
}

/*
        Send an asynchronous MIDI message.
        Assumes that line6->line6midi->lock is held
        (i.e., this function is serialized).
*/
static int send_midi_async(struct usb_line6 *line6, unsigned char *data,
                           int length)
{
        struct urb *urb;
        int retval;
        unsigned char *transfer_buffer;

        urb = usb_alloc_urb(0, GFP_ATOMIC);

        if (urb == NULL)
                return -ENOMEM;

        transfer_buffer = kmemdup(data, length, GFP_ATOMIC);

        if (transfer_buffer == NULL) {
                usb_free_urb(urb);
                return -ENOMEM;
        }

        usb_fill_int_urb(urb, line6->usbdev,
                         usb_sndintpipe(line6->usbdev,
                                         line6->properties->ep_ctrl_w),
                         transfer_buffer, length, midi_sent, line6,
                         line6->interval);
        urb->actual_length = 0;
        retval = usb_urb_ep_type_check(urb);
        if (retval < 0)
                goto error;

        retval = usb_submit_urb(urb, GFP_ATOMIC);
        if (retval < 0)
                goto error;

        ++line6->line6midi->num_active_send_urbs;
        return 0;

 error:
        dev_err(line6->ifcdev, "usb_submit_urb failed\n");
        usb_free_urb(urb);
        return retval;
}

static int line6_midi_output_open(struct snd_rawmidi_substream *substream)
{
        return 0;
}

static int line6_midi_output_close(struct snd_rawmidi_substream *substream)
{
        return 0;
}

static void line6_midi_output_trigger(struct snd_rawmidi_substream *substream,
                                      int up)
{
        struct usb_line6 *line6 =
            line6_rawmidi_substream_midi(substream)->line6;

        line6->line6midi->substream_transmit = substream;
        guard(spinlock_irqsave)(&line6->line6midi->lock);

        if (line6->line6midi->num_active_send_urbs == 0)
                line6_midi_transmit(substream);
}

static void line6_midi_output_drain(struct snd_rawmidi_substream *substream)
{
        struct usb_line6 *line6 =
            line6_rawmidi_substream_midi(substream)->line6;
        struct snd_line6_midi *midi = line6->line6midi;

        wait_event_interruptible(midi->send_wait,
                                 midi->num_active_send_urbs == 0);
}

static int line6_midi_input_open(struct snd_rawmidi_substream *substream)
{
        return 0;
}

static int line6_midi_input_close(struct snd_rawmidi_substream *substream)
{
        return 0;
}

static void line6_midi_input_trigger(struct snd_rawmidi_substream *substream,
                                     int up)
{
        struct usb_line6 *line6 =
            line6_rawmidi_substream_midi(substream)->line6;

        if (up)
                line6->line6midi->substream_receive = substream;
        else
                line6->line6midi->substream_receive = NULL;
}

static const struct snd_rawmidi_ops line6_midi_output_ops = {
        .open = line6_midi_output_open,
        .close = line6_midi_output_close,
        .trigger = line6_midi_output_trigger,
        .drain = line6_midi_output_drain,
};

static const struct snd_rawmidi_ops line6_midi_input_ops = {
        .open = line6_midi_input_open,
        .close = line6_midi_input_close,
        .trigger = line6_midi_input_trigger,
};

/* Create a MIDI device */
static int snd_line6_new_midi(struct usb_line6 *line6,
                              struct snd_rawmidi **rmidi_ret)
{
        struct snd_rawmidi *rmidi;
        int err;

        err = snd_rawmidi_new(line6->card, "Line 6 MIDI", 0, 1, 1, rmidi_ret);
        if (err < 0)
                return err;

        rmidi = *rmidi_ret;
        strscpy(rmidi->id, line6->properties->id);
        strscpy(rmidi->name, line6->properties->name);

        rmidi->info_flags =
            SNDRV_RAWMIDI_INFO_OUTPUT |
            SNDRV_RAWMIDI_INFO_INPUT | SNDRV_RAWMIDI_INFO_DUPLEX;

        snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
                            &line6_midi_output_ops);
        snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT,
                            &line6_midi_input_ops);
        return 0;
}

/* MIDI device destructor */
static void snd_line6_midi_free(struct snd_rawmidi *rmidi)
{
        struct snd_line6_midi *line6midi = rmidi->private_data;

        line6_midibuf_destroy(&line6midi->midibuf_in);
        line6_midibuf_destroy(&line6midi->midibuf_out);
        kfree(line6midi);
}

/*
        Initialize the Line 6 MIDI subsystem.
*/
int line6_init_midi(struct usb_line6 *line6)
{
        int err;
        struct snd_rawmidi *rmidi;
        struct snd_line6_midi *line6midi;

        if (!(line6->properties->capabilities & LINE6_CAP_CONTROL_MIDI)) {
                /* skip MIDI initialization and report success */
                return 0;
        }

        err = snd_line6_new_midi(line6, &rmidi);
        if (err < 0)
                return err;

        line6midi = kzalloc_obj(struct snd_line6_midi);
        if (!line6midi)
                return -ENOMEM;

        rmidi->private_data = line6midi;
        rmidi->private_free = snd_line6_midi_free;

        init_waitqueue_head(&line6midi->send_wait);
        spin_lock_init(&line6midi->lock);
        line6midi->line6 = line6;

        err = line6_midibuf_init(&line6midi->midibuf_in, MIDI_BUFFER_SIZE, 0);
        if (err < 0)
                return err;

        err = line6_midibuf_init(&line6midi->midibuf_out, MIDI_BUFFER_SIZE, 1);
        if (err < 0)
                return err;

        line6->line6midi = line6midi;
        return 0;
}
EXPORT_SYMBOL_GPL(line6_init_midi);