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/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)

void *videobuf_alloc(struct videobuf_queue *q)
{
	struct videobuf_buffer *vb;

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

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

	vb = q->int_ops->alloc(q->msize);

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

	return vb;
}

int videobuf_waiton(struct videobuf_buffer *vb, int non_blocking, int intr)
{
	int retval = 0;
	DECLARE_WAITQUEUE(wait, current);

	MAGIC_CHECK(vb->magic, MAGIC_BUFFER);
	add_wait_queue(&vb->done, &wait);
	while (vb->state == VIDEOBUF_ACTIVE || vb->state == VIDEOBUF_QUEUED) {
		if (non_blocking) {
			retval = -EAGAIN;
			break;
		}
		set_current_state(intr  ? TASK_INTERRUPTIBLE
					: TASK_UNINTERRUPTIBLE);
		if (vb->state == VIDEOBUF_ACTIVE ||
		    vb->state == VIDEOBUF_QUEUED)
			schedule();
		set_current_state(TASK_RUNNING);
		if (intr && signal_pending(current)) {
			dprintk(1, "buffer waiton: -EINTR\n");
			retval = -EINTR;
			break;
		}
	}
	remove_wait_queue(&vb->done, &wait);
	return retval;
}

int videobuf_iolock(struct videobuf_queue *q, struct videobuf_buffer *vb,
		    struct v4l2_framebuffer *fbuf)
{
	MAGIC_CHECK(vb->magic, MAGIC_BUFFER);
	MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);

	/* This is required to avoid OOPS on some cases,
	   since mmap_mapper() method should be called before _iolock.
	   On some cases, the mmap_mapper() is called only after scheduling.
	 */
	if (vb->memory == V4L2_MEMORY_MMAP) {
		wait_event_timeout(vb->done, q->is_mmapped,
				   msecs_to_jiffies(100));
		if (!q->is_mmapped) {
			printk(KERN_ERR
			       "Error: mmap_mapper() never called!\n");
			return -EINVAL;
		}
	}

	return CALL(q, iolock, q, vb, fbuf);
}

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


void videobuf_queue_core_init(struct videobuf_queue *q,
			 struct videobuf_queue_ops *ops,
			 void *dev,
			 spinlock_t *irqlock,
			 enum v4l2_buf_type type,
			 enum v4l2_field field,
			 unsigned int msize,
			 void *priv,
			 struct videobuf_qtype_ops *int_ops)
{
	memset(q, 0, sizeof(*q));
	q->irqlock   = irqlock;
	q->dev       = dev;
	q->type      = type;
	q->field     = field;
	q->msize     = msize;
	q->ops