path: root/drivers/media/video/videobuf-core.c

/*
 * generic helper functions for handling video4linux capture buffers
 *
 * (c) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org>
 *
 * Highly based on video-buf written originally by:
 * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
 * (c) 2006 Mauro Carvalho Chehab, <mchehab@infradead.org>
 * (c) 2006 Ted Walther and John Sokol
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/interrupt.h>

#include <media/videobuf-core.h>

#define MAGIC_BUFFER 0x20070728
#define MAGIC_CHECK(is, should)						\
	do {								\
		if (unlikely((is) != (should))) {			\
			printk(KERN_ERR					\
				"magic mismatch: %x (expected %x)\n",	\
					is, should);			\
			BUG();						\
		}							\
	} while (0)

static int debug;
module_param(debug, int, 0644);

MODULE_DESCRIPTION("helper module to manage video4linux buffers");
MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
MODULE_LICENSE("GPL");

#define dprintk(level, fmt, arg...)					\
	do {								\
		if (debug >= level)					\
			printk(KERN_DEBUG "vbuf: " fmt, ## arg);	\
	} while (0)

/* --------------------------------------------------------------------- */

#define CALL(q, f, arg...)						\
	((q->int_ops->f) ? q->int_ops->f(arg) : 0)

struct videobuf_buffer *videobuf_alloc_vb(struct videobuf_queue *q)
{
	struct videobuf_buffer *vb;

	BUG_ON(q->msize < sizeof(*vb));

	if (!q->int_ops || !q->int_ops->alloc_vb) {
		printk(KERN_ERR "No specific ops defined!\n");
		BUG();
	}

	vb = q->int_ops->alloc_vb(q->msize);
	if (NULL != vb) {
		init_waitqueue_head(&vb->done);
		vb->magic = MAGIC_BUFFER;
	}

	return vb;
}
EXPORT_SYMBOL_GPL(videobuf_alloc_vb);

static int is_state_active_or_queued(struct videobuf_queue *q, struct videobuf_buffer *vb)
{
	unsigned long flags;
	bool rc;

	spin_lock_irqsave(q->irqlock, flags);
	rc = vb->state != VIDEOBUF_ACTIVE && vb->state != VIDEOBUF_QUEUED;
	spin_unlock_irqrestore(q->irqlock, flags);
	return rc;
};

int videobuf_waiton(struct videobuf_queue *q, struct videobuf_buffer *vb,
		int non_blocking, int intr)
{
	bool is_ext_locked;
	int ret = 0;

	MAGIC_CHECK(vb->magic, MAGIC_BUFFER);

	if (non_blocking) {
		if (is_state_active_or_queued(q, vb))
			return 0;
		return -EAGAIN;
	}

	is_ext_locked = q->ext_lock && mutex_is_locked(q->ext_lock);

	/* Release vdev lock to prevent this wait from blocking outside access to
	   the device. */
	if (is_ext_locked)
		mutex_unlock(q->ext_lock);
	if (intr)
		ret = wait_event_interruptible(vb->done, is_state_active_or_queued(q, vb));
	else
		wait_event(vb->done, is_state_active_or_queued(q, vb));
	/* Relock */
	if (is_ext_locked)
		mutex_lock(q->ext_lock);

	return ret;
}
EXPORT_SYMBOL_GPL(videobuf_waiton);