[media] v4l: move v4l2 core into a separate directory

Currently, the v4l2 core is mixed together with other non-core drivers.
Move them into a separate directory.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 647 insertions, 0 deletions

diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c
new file mode 100644
index 000000000000..97b48318aee1
--- /dev/null
+++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
@@ -0,0 +1,647 @@
+/*
+ * 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, <pawel@osciak.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>
+#include <media/v4l2-dev.h>
+#include <media/v4l2-fh.h>
+#include <media/v4l2-event.h>
+
+MODULE_DESCRIPTION("Mem to mem device framework for videobuf");
+MODULE_AUTHOR("Pawel Osciak, <pawel@osciak.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)) {
+		spin_unlock_irqrestore(&q_ctx->rdy_spinlock, flags);
+		return NULL;
+	}
+
+	b = list_entry(q_ctx->rdy_queue.next, struct v4l2_m2m_buffer, list);
+	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)) {
+		spin_unlock_irqrestore(&q_ctx->rdy_spinlock, flags);
+		return NULL;
+	}
+	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 currently running\n");
+		return;
+	}
+
+	list_del(&m2m_dev->curr_ctx->queue);
+	m2m_dev->curr_ctx->job_flags &= ~(TRANS_QUEUED | TRANS_RUNNING);
+	wake_up(&m2m_dev->curr_ctx->finished);
+	m2m_dev->curr_ctx = NULL;
+
+	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
+
+	/* This instance might have more buffers ready, but since we do not
+	 * allow more than one job on the job_queue per instance, each has
+	 * to be scheduled separately after the previous one finishes. */
+	v4l2_m2m_try_schedule(m2m_ctx);
+	v4l2_m2m_try_run(m2m_dev);
+}
+EXPORT_SYMBOL(v4l2_m2m_job_finish);
+
+/**
+ * v4l2_m2m_reqbufs() - multi-queue-aware REQBUFS multiplexer
+ */
+int v4l2_m2m_reqbufs(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
+		     struct v4l2_requestbuffers *reqbufs)
+{
+	struct vb2_queue *vq;
+
+	vq = v4l2_m2m_get_vq(m2m_ctx, reqbufs->type);
+	return vb2_reqbufs(vq, reqbufs);
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_reqbufs);
+
+/**
+ * v4l2_m2m_querybuf() - multi-queue-aware QUERYBUF multiplexer
+ *
+ * See v4l2_m2m_mmap() documentation for details.
+ */
+int v4l2_m2m_querybuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
+		      struct v4l2_buffer *buf)
+{
+	struct vb2_queue *vq;
+	int ret = 0;
+	unsigned int i;
+
+	vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
+	ret = vb2_querybuf(vq, buf);
+
+	/* Adjust MMAP memory offsets for the CAPTURE queue */
+	if (buf->memory == V4L2_MEMORY_MMAP && !V4L2_TYPE_IS_OUTPUT(vq->type)) {
+		if (V4L2_TYPE_IS_MULTIPLANAR(vq->type)) {
+			for (i = 0; i < buf->length; ++i)
+				buf->m.planes[i].m.mem_offset
+					+= DST_QUEUE_OFF_BASE;
+		} else {
+			buf->m.offset += DST_QUEUE_OFF_BASE;
+		}
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_querybuf);
+
+/**
+ * v4l2_m2m_qbuf() - enqueue a source or destination buffer, depending on
+ * the type
+ */
+int v4l2_m2m_qbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
+		  struct v4l2_buffer *buf)
+{
+	struct vb2_queue *vq;
+	int ret;
+
+	vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
+	ret = vb2_qbuf(vq, buf);
+	if (!ret)
+		v4l2_m2m_try_schedule(m2m_ctx);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_qbuf);
+
+/**
+ * v4l2_m2m_dqbuf() - dequeue a source or destination buffer, depending on
+ * the type
+ */
+int v4l2_m2m_dqbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
+		   struct v4l2_buffer *buf)
+{
+	struct vb2_queue *vq;
+
+	vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
+	return vb2_dqbuf(vq, buf, file->f_flags & O_NONBLOCK);
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_dqbuf);
+
+/**
+ * v4l2_m2m_streamon() - turn on streaming for a video queue
+ */
+int v4l2_m2m_streamon(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
+		      enum v4l2_buf_type type)
+{
+	struct vb2_queue *vq;
+	int ret;
+
+	vq = v4l2_m2m_get_vq(m2m_ctx, type);
+	ret = vb2_streamon(vq, type);
+	if (!ret)
+		v4l2_m2m_try_schedule(m2m_ctx);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_streamon);
+
+/**
+ * v4l2_m2m_streamoff() - turn off streaming for a video queue
+ */
+int v4l2_m2m_streamoff(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
+		       enum v4l2_buf_type type)
+{
+	struct vb2_queue *vq;
+
+	vq = v4l2_m2m_get_vq(m2m_ctx, type);
+	return vb2_streamoff(vq, type);
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_streamoff);
+
+/**
+ * v4l2_m2m_poll() - poll replacement, for destination buffers only
+ *
+ * Call from the driver's poll() function. Will poll both queues. If a buffer
+ * is available to dequeue (with dqbuf) from the source queue, this will
+ * indicate that a non-blocking write can be performed, while read will be
+ * returned in case of the destination queue.
+ */
+unsigned int v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
+			   struct poll_table_struct *wait)
+{
+	struct video_device *vfd = video_devdata(file);
+	unsigned long req_events = poll_requested_events(wait);
+	struct vb2_queue *src_q, *dst_q;
+	struct vb2_buffer *src_vb = NULL, *dst_vb = NULL;
+	unsigned int rc = 0;
+	unsigned long flags;
+
+	if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags)) {
+		struct v4l2_fh *fh = file->private_data;
+
+		if (v4l2_event_pending(fh))
+			rc = POLLPRI;
+		else if (req_events & POLLPRI)
+			poll_wait(file, &fh->wait, wait);
+		if (!(req_events & (POLLOUT | POLLWRNORM | POLLIN | POLLRDNORM)))
+			return rc;
+	}
+
+	src_q = v4l2_m2m_get_src_vq(m2m_ctx);
+	dst_q = v4l2_m2m_get_dst_vq(m2m_ctx);
+
+	/*
+	 * There has to be at least one buffer queued on each queued_list, which
+	 * means either in driver already or waiting for driver to claim it
+	 * and start processing.
+	 */
+	if ((!src_q->streaming || list_empty(&src_q->queued_list))
+		&& (!dst_q->streaming || list_empty(&dst_q->queued_list))) {
+		rc |= POLLERR;
+		goto end;
+	}
+
+	if (m2m_ctx->m2m_dev->m2m_ops->unlock)
+		m2m_ctx->m2m_dev->m2m_ops->unlock(m2m_ctx->priv);
+
+	poll_wait(file, &src_q->done_wq, wait);
+	poll_wait(file, &dst_q->done_wq, wait);
+
+	if (m2m_ctx->m2m_dev->m2m_ops->lock)
+		m2m_ctx->m2m_dev->m2m_ops->lock(m2m_ctx->priv);
+
+	spin_lock_irqsave(&src_q->done_lock, flags);
+	if (!list_empty(&src_q->done_list))
+		src_vb = list_first_entry(&src_q->done_list, struct vb2_buffer,
+						done_entry);
+	if (src_vb && (src_vb->state == VB2_BUF_STATE_DONE
+			|| src_vb->state == VB2_BUF_STATE_ERROR))
+		rc |= POLLOUT | POLLWRNORM;
+	spin_unlock_irqrestore(&src_q->done_lock, flags);
+
+	spin_lock_irqsave(&dst_q->done_lock, flags);
+	if (!list_empty(&dst_q->done_list))
+		dst_vb = list_first_entry(&dst_q->done_list, struct vb2_buffer,
+						done_entry);
+	if (dst_vb && (dst_vb->state == VB2_BUF_STATE_DONE
+			|| dst_vb->state == VB2_BUF_STATE_ERROR))
+		rc |= POLLIN | POLLRDNORM;
+	spin_unlock_irqrestore(&dst_q->done_lock, flags);
+
+end:
+	return rc;
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_poll);
+
+/**
+ * v4l2_m2m_mmap() - source and destination queues-aware mmap multiplexer
+ *
+ * Call from driver's mmap() function. Will handle mmap() for both queues
+ * seamlessly for videobuffer, which will receive normal per-queue offsets and
+ * proper videobuf queue pointers. The differentiation is made outside videobuf
+ * by adding a predefined offset to buffers from one of the queues and
+ * subtracting it before passing it back to videobuf. Only drivers (and
+ * thus applications) receive modified offsets.
+ */
+int v4l2_m2m_mmap(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
+			 struct vm_area_struct *vma)
+{
+	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
+	struct vb2_queue *vq;
+
+	if (offset < DST_QUEUE_OFF_BASE) {
+		vq = v4l2_m2m_get_src_vq(m2m_ctx);
+	} else {
+		vq = v4l2_m2m_get_dst_vq(m2m_ctx);
+		vma->vm_pgoff -= (DST_QUEUE_OFF_BASE >> PAGE_SHIFT);
+	}
+
+	return vb2_mmap(vq, vma);
+}
+EXPORT_SYMBOL(v4l2_m2m_mmap);
+
+/**
+ * v4l2_m2m_init() - initialize per-driver m2m data
+ *
+ * Usually called from driver's probe() function.
+ */
+struct v4l2_m2m_dev *v4l2_m2m_init(struct v4l2_m2m_ops *m2m_ops)
+{
+	struct v4l2_m2m_dev *m2m_dev;
+
+	if (!m2m_ops)
+		return ERR_PTR(-EINVAL);
+
+	BUG_ON(!m2m_ops->device_run);
+	BUG_ON(!m2m_ops->job_abort);
+
+	m2m_dev = kzalloc(sizeof *m2m_dev, GFP_KERNEL);
+	if (!m2m_dev)
+		return ERR_PTR(-ENOMEM);
+
+	m2m_dev->curr_ctx = NULL;
+	m2m_dev->m2m_ops = m2m_ops;
+	INIT_LIST_HEAD(&m2m_dev->job_queue);
+	spin_lock_init(&m2m_dev->job_spinlock);
+
+	return m2m_dev;
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_init);
+
+/**
+ * v4l2_m2m_release() - cleans up and frees a m2m_dev structure
+ *
+ * Usually called from driver's remove() function.
+ */
+void v4l2_m2m_release(struct v4l2_m2m_dev *m2m_dev)
+{
+	kfree(m2m_dev);
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_release);
+
+/**
+ * v4l2_m2m_ctx_init() - allocate and initialize a m2m context
+ * @priv - driver's instance private data
+ * @m2m_dev - a previously initialized m2m_dev struct
+ * @vq_init - a callback for queue type-specific initialization function to be
+ * used for initializing videobuf_queues
+ *
+ * Usually called from driver's open() function.
+ */
+struct v4l2_m2m_ctx *v4l2_m2m_ctx_init(struct v4l2_m2m_dev *m2m_dev,
+		void *drv_priv,
+		int (*queue_init)(void *priv, struct vb2_queue *src_vq, struct vb2_queue *dst_vq))
+{
+	struct v4l2_m2m_ctx *m2m_ctx;
+	struct v4l2_m2m_queue_ctx *out_q_ctx, *cap_q_ctx;
+	int ret;
+
+	m2m_ctx = kzalloc(sizeof *m2m_ctx, GFP_KERNEL);
+	if (!m2m_ctx)
+		return ERR_PTR(-ENOMEM);
+
+	m2m_ctx->priv = drv_priv;
+	m2m_ctx->m2m_dev = m2m_dev;
+	init_waitqueue_head(&m2m_ctx->finished);
+
+	out_q_ctx = &m2m_ctx->out_q_ctx;
+	cap_q_ctx = &m2m_ctx->cap_q_ctx;
+
+	INIT_LIST_HEAD(&out_q_ctx->rdy_queue);
+	INIT_LIST_HEAD(&cap_q_ctx->rdy_queue);
+	spin_lock_init(&out_q_ctx->rdy_spinlock);
+	spin_lock_init(&cap_q_ctx->rdy_spinlock);
+
+	INIT_LIST_HEAD(&m2m_ctx->queue);
+
+	ret = queue_init(drv_priv, &out_q_ctx->q, &cap_q_ctx->q);
+
+	if (ret)
+		goto err;
+
+	return m2m_ctx;
+err:
+	kfree(m2m_ctx);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_ctx_init);
+
+/**
+ * v4l2_m2m_ctx_release() - release m2m context
+ *
+ * Usually called from driver's release() function.
+ */
+void v4l2_m2m_ctx_release(struct v4l2_m2m_ctx *m2m_ctx)
+{
+	struct v4l2_m2m_dev *m2m_dev;
+	unsigned long flags;
+
+	m2m_dev = m2m_ctx->m2m_dev;
+
+	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
+	if (m2m_ctx->job_flags & TRANS_RUNNING) {
+		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
+		m2m_dev->m2m_ops->job_abort(m2m_ctx->priv);
+		dprintk("m2m_ctx %p running, will wait to complete", m2m_ctx);
+		wait_event(m2m_ctx->finished, !(m2m_ctx->job_flags & TRANS_RUNNING));
+	} else if (m2m_ctx->job_flags & TRANS_QUEUED) {
+		list_del(&m2m_ctx->queue);
+		m2m_ctx->job_flags &= ~(TRANS_QUEUED | TRANS_RUNNING);
+		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
+		dprintk("m2m_ctx: %p had been on queue and was removed\n",
+			m2m_ctx);
+	} else {
+		/* Do nothing, was not on queue/running */
+		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
+	}
+
+	vb2_queue_release(&m2m_ctx->cap_q_ctx.q);
+	vb2_queue_release(&m2m_ctx->out_q_ctx.q);
+
+	kfree(m2m_ctx);
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_ctx_release);
+
+/**
+ * v4l2_m2m_buf_queue() - add a buffer to the proper ready buffers list.
+ *
+ * Call from buf_queue(), videobuf_queue_ops callback.
+ */
+void v4l2_m2m_buf_queue(struct v4l2_m2m_ctx *m2m_ctx, struct vb2_buffer *vb)
+{
+	struct v4l2_m2m_buffer *b = container_of(vb, struct v4l2_m2m_buffer, vb);
+	struct v4l2_m2m_queue_ctx *q_ctx;
+	unsigned long flags;
+
+	q_ctx = get_queue_ctx(m2m_ctx, vb->vb2_queue->type);
+	if (!q_ctx)
+		return;
+
+	spin_lock_irqsave(&q_ctx->rdy_spinlock, flags);
+	list_add_tail(&b->list, &q_ctx->rdy_queue);
+	q_ctx->num_rdy++;
+	spin_unlock_irqrestore(&q_ctx->rdy_spinlock, flags);
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_buf_queue);
+