sound/core/seq/oss/seq_oss_writeq.c

Source file repositories/reference/linux-study-clean/sound/core/seq/oss/seq_oss_writeq.c

File Facts

System
Linux kernel
Corpus path
sound/core/seq/oss/seq_oss_writeq.c
Extension
.c
Size
3412 bytes
Lines
158
Domain
Driver Families
Bucket
sound/core
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

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

#include "seq_oss_writeq.h"
#include "seq_oss_event.h"
#include "seq_oss_timer.h"
#include <sound/seq_oss_legacy.h>
#include "../seq_lock.h"
#include "../seq_clientmgr.h"
#include <linux/wait.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>


/*
 * create a write queue record
 */
struct seq_oss_writeq *
snd_seq_oss_writeq_new(struct seq_oss_devinfo *dp, int maxlen)
{
	struct seq_oss_writeq *q;
	struct snd_seq_client_pool pool;

	q = kzalloc_obj(*q);
	if (!q)
		return NULL;
	q->dp = dp;
	q->maxlen = maxlen;
	spin_lock_init(&q->sync_lock);
	q->sync_event_put = 0;
	q->sync_time = 0;
	init_waitqueue_head(&q->sync_sleep);

	memset(&pool, 0, sizeof(pool));
	pool.client = dp->cseq;
	pool.output_pool = maxlen;
	pool.output_room = maxlen / 2;

	snd_seq_oss_control(dp, SNDRV_SEQ_IOCTL_SET_CLIENT_POOL, &pool);

	return q;
}

/*
 * delete the write queue
 */
void
snd_seq_oss_writeq_delete(struct seq_oss_writeq *q)
{
	if (q) {
		snd_seq_oss_writeq_clear(q);	/* to be sure */
		kfree(q);
	}
}


/*
 * reset the write queue
 */
void
snd_seq_oss_writeq_clear(struct seq_oss_writeq *q)
{
	struct snd_seq_remove_events reset;

	memset(&reset, 0, sizeof(reset));
	reset.remove_mode = SNDRV_SEQ_REMOVE_OUTPUT; /* remove all */
	snd_seq_oss_control(q->dp, SNDRV_SEQ_IOCTL_REMOVE_EVENTS, &reset);

	/* wake up sleepers if any */
	snd_seq_oss_writeq_wakeup(q, 0);
}

/*
 * wait until the write buffer has enough room
 */
int
snd_seq_oss_writeq_sync(struct seq_oss_writeq *q)
{
	struct seq_oss_devinfo *dp = q->dp;
	abstime_t time;

	time = snd_seq_oss_timer_cur_tick(dp->timer);
	if (q->sync_time >= time)
		return 0; /* already finished */

Annotation

Implementation Notes