// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * OSS compatible sequencer driver
 *
 * seq_oss_readq.c - MIDI input queue
 *
 * Copyright (C) 1998,99 Takashi Iwai <tiwai@suse.de>
 */

#include "seq_oss_readq.h"
#include "seq_oss_event.h"
#include <sound/seq_oss_legacy.h>
#include "../seq_lock.h"
#include <linux/wait.h>
#include <linux/slab.h>

/*
 * constants
 */
//#define SNDRV_SEQ_OSS_MAX_TIMEOUT     (unsigned long)(-1)
#define SNDRV_SEQ_OSS_MAX_TIMEOUT       (HZ * 3600)


/*
 * prototypes
 */


/*
 * create a read queue
 */
struct seq_oss_readq *
snd_seq_oss_readq_new(struct seq_oss_devinfo *dp, int maxlen)
{
        struct seq_oss_readq *q;

        q = kzalloc_obj(*q);
        if (!q)
                return NULL;

        q->q = kzalloc_objs(union evrec, maxlen);
        if (!q->q) {
                kfree(q);
                return NULL;
        }

        q->maxlen = maxlen;
        q->qlen = 0;
        q->head = q->tail = 0;
        init_waitqueue_head(&q->midi_sleep);
        spin_lock_init(&q->lock);
        q->pre_event_timeout = SNDRV_SEQ_OSS_MAX_TIMEOUT;
        q->input_time = (unsigned long)-1;

        return q;
}

/*
 * delete the read queue
 */
void
snd_seq_oss_readq_delete(struct seq_oss_readq *q)
{
        if (q) {
                kfree(q->q);
                kfree(q);
        }
}

/*
 * reset the read queue
 */
void
snd_seq_oss_readq_clear(struct seq_oss_readq *q)
{
        if (q->qlen) {
                q->qlen = 0;
                q->head = q->tail = 0;
        }
        /* if someone sleeping, wake'em up */
        wake_up(&q->midi_sleep);
        q->input_time = (unsigned long)-1;
}

/*
 * put a midi byte
 */
int
snd_seq_oss_readq_puts(struct seq_oss_readq *q, int dev, unsigned char *data, int len)
{
        union evrec rec;
        int result;

        memset(&rec, 0, sizeof(rec));
        rec.c[0] = SEQ_MIDIPUTC;
        rec.c[2] = dev;

        while (len-- > 0) {
                rec.c[1] = *data++;
                result = snd_seq_oss_readq_put_event(q, &rec);
                if (result < 0)
                        return result;
        }
        return 0;
}

/*
 * put MIDI sysex bytes; the event buffer may be chained, thus it has
 * to be expanded via snd_seq_dump_var_event().
 */
struct readq_sysex_ctx {
        struct seq_oss_readq *readq;
        int dev;
};

static int readq_dump_sysex(void *ptr, void *buf, int count)
{
        struct readq_sysex_ctx *ctx = ptr;

        return snd_seq_oss_readq_puts(ctx->readq, ctx->dev, buf, count);
}

int snd_seq_oss_readq_sysex(struct seq_oss_readq *q, int dev,
                            struct snd_seq_event *ev)
{
        struct readq_sysex_ctx ctx = {
                .readq = q,
                .dev = dev
        };

        if ((ev->flags & SNDRV_SEQ_EVENT_LENGTH_MASK) != SNDRV_SEQ_EVENT_LENGTH_VARIABLE)
                return 0;
        return snd_seq_dump_var_event(ev, readq_dump_sysex, &ctx);
}

/*
 * copy an event to input queue:
 * return zero if enqueued
 */
int
snd_seq_oss_readq_put_event(struct seq_oss_readq *q, union evrec *ev)
{
        guard(spinlock_irqsave)(&q->lock);
        if (q->qlen >= q->maxlen - 1)
                return -ENOMEM;

        memcpy(&q->q[q->tail], ev, sizeof(*ev));
        q->tail = (q->tail + 1) % q->maxlen;
        q->qlen++;

        /* wake up sleeper */
        wake_up(&q->midi_sleep);

        return 0;
}


/*
 * pop queue
 * caller must hold lock
 */
int
snd_seq_oss_readq_pick(struct seq_oss_readq *q, union evrec *rec)
{
        if (q->qlen == 0)
                return -EAGAIN;
        memcpy(rec, &q->q[q->head], sizeof(*rec));
        return 0;
}

/*
 * sleep until ready
 */
void
snd_seq_oss_readq_wait(struct seq_oss_readq *q)
{
        wait_event_interruptible_timeout(q->midi_sleep,
                                         (q->qlen > 0 || q->head == q->tail),
                                         q->pre_event_timeout);
}

/*
 * drain one record
 * caller must hold lock
 */
void
snd_seq_oss_readq_free(struct seq_oss_readq *q)
{
        if (q->qlen > 0) {
                q->head = (q->head + 1) % q->maxlen;
                q->qlen--;
        }
}

/*
 * polling/select:
 * return non-zero if readq is not empty.
 */
unsigned int
snd_seq_oss_readq_poll(struct seq_oss_readq *q, struct file *file, poll_table *wait)
{
        poll_wait(file, &q->midi_sleep, wait);
        return q->qlen;
}

/*
 * put a timestamp
 */
int
snd_seq_oss_readq_put_timestamp(struct seq_oss_readq *q, unsigned long curt, int seq_mode)
{
        if (curt != q->input_time) {
                union evrec rec;
                memset(&rec, 0, sizeof(rec));
                switch (seq_mode) {
                case SNDRV_SEQ_OSS_MODE_SYNTH:
                        rec.echo = (curt << 8) | SEQ_WAIT;
                        snd_seq_oss_readq_put_event(q, &rec);
                        break;
                case SNDRV_SEQ_OSS_MODE_MUSIC:
                        rec.t.code = EV_TIMING;
                        rec.t.cmd = TMR_WAIT_ABS;
                        rec.t.time = curt;
                        snd_seq_oss_readq_put_event(q, &rec);
                        break;
                }
                q->input_time = curt;
        }
        return 0;
}


#ifdef CONFIG_SND_PROC_FS
/*
 * proc interface
 */
void
snd_seq_oss_readq_info_read(struct seq_oss_readq *q, struct snd_info_buffer *buf)
{
        snd_iprintf(buf, "  read queue [%s] length = %d : tick = %ld\n",
                    (waitqueue_active(&q->midi_sleep) ? "sleeping":"running"),
                    q->qlen, q->input_time);
}
#endif /* CONFIG_SND_PROC_FS */