path: root/drivers/media/video/v4l2-mem2mem.c

/*
 * Memory-to-memory device framework for Video for Linux 2 and videobuf.
 *
 * Helper functions for devices that use videobuf buffers for both their
 * source and destination.
 *
 * Copyright (c) 2009-2010 Samsung Electronics Co., Ltd.
 * Pawel Osciak, <p.osciak@samsung.com>
 * Marek Szyprowski, <m.szyprowski@samsung.com>
 *
 * 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 of the License, or (at your
 * option) any later version.
 */
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include <media/videobuf2-core.h>
#include <media/v4l2-mem2mem.h>

MODULE_DESCRIPTION("Mem to mem device framework for videobuf");
MODULE_AUTHOR("Pawel Osciak, <p.osciak@samsung.com>");
MODULE_LICENSE("GPL");

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

#define dprintk(fmt, arg...)						\
	do {								\
		if (debug)						\
			printk(KERN_DEBUG "%s: " fmt, __func__, ## arg);\
	} while (0)


/* Instance is already queued on the job_queue */
#define TRANS_QUEUED		(1 << 0)
/* Instance is currently running in hardware */
#define TRANS_RUNNING		(1 << 1)


/* Offset base for buffers on the destination queue - used to distinguish
 * between source and destination buffers when mmapping - they receive the same
 * offsets but for different queues */
#define DST_QUEUE_OFF_BASE	(1 << 30)


/**
 * struct v4l2_m2m_dev - per-device context
 * @curr_ctx:		currently running instance
 * @job_queue:		instances queued to run
 * @job_spinlock:	protects job_queue
 * @m2m_ops:		driver callbacks
 */
struct v4l2_m2m_dev {
	struct v4l2_m2m_ctx	*curr_ctx;

	struct list_head	job_queue;
	spinlock_t		job_spinlock;

	struct v4l2_m2m_ops	*m2m_ops;
};

static struct v4l2_m2m_queue_ctx *get_queue_ctx(struct v4l2_m2m_ctx *m2m_ctx,
						enum v4l2_buf_type type)
{
	if (V4L2_TYPE_IS_OUTPUT(type))
		return &m2m_ctx->out_q_ctx;
	else
		return &m2m_ctx->cap_q_ctx;
}

/**
 * v4l2_m2m_get_vq() - return vb2_queue for the given type
 */
struct vb2_queue *v4l2_m2m_get_vq(struct v4l2_m2m_ctx *m2m_ctx,
				       enum v4l2_buf_type type)
{
	struct v4l2_m2m_queue_ctx *q_ctx;

	q_ctx = get_queue_ctx(m2m_ctx, type);
	if (!q_ctx)
		return NULL;

	return &q_ctx->q;
}
EXPORT_SYMBOL(v4l2_m2m_get_vq);

/**
 * v4l2_m2m_next_buf() - return next buffer from the list of ready buffers
 */
void *v4l2_m2m_next_buf(struct v4l2_m2m_queue_ctx *q_ctx)
{
	struct v4l2_m2m_buffer *b = NULL;
	unsigned long flags;

	spin_lock_irqsave(&q_ctx->rdy_spinlock, flags);

	if (list_empty(&q_ctx->rdy_queue))
		goto end;

	b = list_entry(q_ctx->rdy_queue.next, struct v4l2_m2m_buffer, list);
end:
	spin_unlock_irqrestore(&q_ctx->rdy_spinlock, flags);
	return &b->vb;
}
EXPORT_SYMBOL_GPL(v4l2_m2m_next_buf);

/**
 * v4l2_m2m_buf_remove() - take off a buffer from the list of ready buffers and
 * return it
 */
void *v4l2_m2m_buf_remove(struct v4l2_m2m_queue_ctx *q_ctx)
{
	struct v4l2_m2m_buffer *b = NULL;
	unsigned long flags;

	spin_lock_irqsave(&q_ctx->rdy_spinlock, flags);
	if (!list_empty(&q_ctx->rdy_queue)) {
		b = list_entry(q_ctx->rdy_queue.next, struct v4l2_m2m_buffer,
				list);
		list_del(&b->list);
		q_ctx->num_rdy--;
	}
	spin_unlock_irqrestore(&q_ctx->rdy_spinlock, flags);

	return &b->vb;
}
EXPORT_SYMBOL_GPL(v4l2_m2m_buf_remove);

/*
 * Scheduling handlers
 */

/**
 * v4l2_m2m_get_curr_priv() - return driver private data for the currently
 * running instance or NULL if no instance is running
 */
void *v4l2_m2m_get_curr_priv(struct v4l2_m2m_dev *m2m_dev)
{
	unsigned long flags;
	void *ret = NULL;

	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
	if (m2m_dev->curr_ctx)
		ret = m2m_dev->curr_ctx->priv;
	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);

	return ret;
}
EXPORT_SYMBOL(v4l2_m2m_get_curr_priv);

/**
 * v4l2_m2m_try_run() - select next job to perform and run it if possible
 *
 * Get next transaction (if present) from the waiting jobs list and run it.
 */
static void v4l2_m2m_try_run(struct v4l2_m2m_dev *m2m_dev)
{
	unsigned long flags;

	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
	if (NULL != m2m_dev->curr_ctx) {
		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
		dprintk("Another instance is running, won't run now\n");
		return;
	}

	if (list_empty(&m2m_dev->job_queue)) {
		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
		dprintk("No job pending\n");
		return;
	}

	m2m_dev->curr_ctx = list_entry(m2m_dev->job_queue.next,
				   struct v4l2_m2m_ctx, queue);
	m2m_dev->curr_ctx->job_flags |= TRANS_RUNNING;
	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);

	m2m_dev->m2m_ops->device_run(m2m_dev->curr_ctx->priv);
}

/**
 * v4l2_m2m_try_schedule() - check whether an instance is ready to be added to
 * the pending job queue and add it if so.
 * @m2m_ctx:	m2m context assigned to the instance to be checked
 *
 * There are three basic requirements an instance has to meet to be able to run:
 * 1) at least one source buffer has to be queued,
 * 2) at least one destination buffer has to be queued,
 * 3) streaming has to be on.
 *
 * There may also be additional, custom requirements. In such case the driver
 * should supply a custom callback (job_ready in v4l2_m2m_ops) that should
 * return 1 if the instance is ready.
 * An example of the above could be an instance that requires more than one
 * src/dst buffer per transaction.
 */
static void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx *m2m_ctx)
{
	struct v4l2_m2m_dev *m2m_dev;
	unsigned long flags_job, flags;

	m2m_dev = m2m_ctx->m2m_dev;
	dprintk("Trying to schedule a job for m2m_ctx: %p\n", m2m_ctx);

	if (!m2m_ctx->out_q_ctx.q.streaming
	    || !m2m_ctx->cap_q_ctx.q.streaming) {
		dprintk("Streaming needs to be on for both queues\n");
		return;
	}

	spin_lock_irqsave(&m2m_dev->job_spinlock, flags_job);
	if (m2m_ctx->job_flags & TRANS_QUEUED) {
		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
		dprintk("On job queue already\n");
		return;
	}

	spin_lock_irqsave(&m2m_ctx->out_q_ctx.rdy_spinlock, flags);
	if (list_empty(&m2m_ctx->out_q_ctx.rdy_queue)) {
		spin_unlock_irqrestore(&m2m_ctx->out_q_ctx.rdy_spinlock, flags);
		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
		dprintk("No input buffers available\n");
		return;
	}
	if (list_empty(&m2m_ctx->cap_q_ctx.rdy_queue)) {
		spin_unlock_irqrestore(&m2m_ctx->out_q_ctx.rdy_spinlock, flags);
		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
		dprintk("No output buffers available\n");
		return;
	}
	spin_unlock_irqrestore(&m2m_ctx->out_q_ctx.rdy_spinlock, flags);

	if (m2m_dev->m2m_ops->job_ready
		&& (!m2m_dev->m2m_ops->job_ready(m2m_ctx->priv))) {
		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
		dprintk("Driver not ready\n");
		return;
	}

	list_add_tail(&m2m_ctx->queue, &m2m_dev->job_queue);
	m2m_ctx->job_flags |= TRANS_QUEUED;

	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);

	v4l2_m2m_try_run(m2m_dev);
}

/**
 * v4l2_m2m_job_finish() - inform the framework that a job has been finished
 * and have it clean up
 *
 * Called by a driver to yield back the device after it has finished with it.
 * Should be called as soon as possible after reaching a state which allows
 * other instances to take control of the device.
 *
 * This function has to be called only after device_run() callback has been
 * called on the driver. To prevent recursion, it should not be called directly
 * from the device_run() callback though.
 */
void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
			 struct v4l2_m2m_ctx *m2m_ctx)
{
	unsigned long flags;

	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
	if (!m2m_dev->curr_ctx || m2m_dev->curr_ctx != m2m_ctx) {
		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
		dprintk("Called by an instance not current