path: root/include/media/v4l2-mem2mem.h

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Memory-to-memory device framework for Video for Linux 2.
 *
 * Helper functions for devices that use memory buffers for both source
 * and destination.
 *
 * Copyright (c) 2009 Samsung Electronics Co., Ltd.
 * Pawel Osciak, <pawel@osciak.com>
 * Marek Szyprowski, <m.szyprowski@samsung.com>
 */

#ifndef _MEDIA_V4L2_MEM2MEM_H
#define _MEDIA_V4L2_MEM2MEM_H

#include <media/videobuf2-v4l2.h>

/**
 * struct v4l2_m2m_ops - mem-to-mem device driver callbacks
 * @device_run:	required. Begin the actual job (transaction) inside this
 *		callback.
 *		The job does NOT have to end before this callback returns
 *		(and it will be the usual case). When the job finishes,
 *		v4l2_m2m_job_finish() or v4l2_m2m_buf_done_and_job_finish()
 *		has to be called.
 * @job_ready:	optional. Should return 0 if the driver does not have a job
 *		fully prepared to run yet (i.e. it will not be able to finish a
 *		transaction without sleeping). If not provided, it will be
 *		assumed that one source and one destination buffer are all
 *		that is required for the driver to perform one full transaction.
 *		This method may not sleep.
 * @job_abort:	optional. Informs the driver that it has to abort the currently
 *		running transaction as soon as possible (i.e. as soon as it can
 *		stop the device safely; e.g. in the next interrupt handler),
 *		even if the transaction would not have been finished by then.
 *		After the driver performs the necessary steps, it has to call
 *		v4l2_m2m_job_finish() or v4l2_m2m_buf_done_and_job_finish() as
 *		if the transaction ended normally.
 *		This function does not have to (and will usually not) wait
 *		until the device enters a state when it can be stopped.
 */
struct v4l2_m2m_ops {
	void (*device_run)(void *priv);
	int (*job_ready)(void *priv);
	void (*job_abort)(void *priv);
};

struct video_device;
struct v4l2_m2m_dev;

/**
 * struct v4l2_m2m_queue_ctx - represents a queue for buffers ready to be
 *	processed
 *
 * @q:		pointer to struct &vb2_queue
 * @rdy_queue:	List of V4L2 mem-to-mem queues
 * @rdy_spinlock: spin lock to protect the struct usage
 * @num_rdy:	number of buffers ready to be processed
 * @buffered:	is the queue buffered?
 *
 * Queue for buffers ready to be processed as soon as this
 * instance receives access to the device.
 */

struct v4l2_m2m_queue_ctx {
	struct vb2_queue	q;

	struct list_head	rdy_queue;
	spinlock_t		rdy_spinlock;
	u8			num_rdy;
	bool			buffered;
};

/**
 * struct v4l2_m2m_ctx - Memory to memory context structure
 *
 * @q_lock: struct &mutex lock
 * @new_frame: valid in the device_run callback: if true, then this
 *		starts a new frame; if false, then this is a new slice
 *		for an existing frame. This is always true unless
 *		V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF is set, which
 *		indicates slicing support.
 * @is_draining: indicates device is in draining phase
 * @last_src_buf: indicate the last source buffer for draining
 * @next_buf_last: next capture queud buffer will be tagged as last
 * @has_stopped: indicate the device has been stopped
 * @m2m_dev: opaque pointer to the internal data to handle M2M context
 * @cap_q_ctx: Capture (output to memory) queue context
 * @out_q_ctx: Output (input from memory) queue context
 * @queue: List of memory to memory contexts
 * @job_flags: Job queue flags, used internally by v4l2-mem2mem.c:
 *		%TRANS_QUEUED, %TRANS_RUNNING and %TRANS_ABORT.
 * @finished: Wait queue used to signalize when a job queue finished.
 * @priv: Instance private data
 *
 * The memory to memory context is specific to a file handle, NOT to e.g.
 * a device.
 */
struct v4l2_m2m_ctx {
	/* optional cap/out vb2 queues lock */
	struct mutex			*q_lock;

	bool				new_frame;

	bool				is_draining;
	struct vb2_v4l2_buffer		*last_src_buf;
	bool				next_buf_last;
	bool				has_stopped;

	/* internal use only */
	struct v4l2_m2m_dev		*m2m_dev;

	struct v4l2_m2m_queue_ctx	cap_q_ctx;

	struct v4l2_m2m_queue_ctx	out_q_ctx;

	/* For device job queue */
	struct list_head		queue;
	unsigned long			job_flags;
	wait_queue_head_t		finished;

	void				*priv;
};

/**
 * struct v4l2_m2m_buffer - Memory to memory buffer
 *
 * @vb: pointer to struct &vb2_v4l2_buffer
 * @list: list of m2m buffers
 */
struct v4l2_m2m_buffer {
	struct vb2_v4l2_buffer	vb;
	struct list_head	list;
};

/**
 * v4l2_m2m_get_curr_priv() - return driver private data for the currently
 * running instance or NULL if no instance is running
 *
 * @m2m_dev: opaque pointer to the internal data to handle M2M context
 */
void *v4l2_m2m_get_curr_priv(struct v4l2_m2m_dev *m2m_dev);

/**
 * v4l2_m2m_get_vq() - return vb2_queue for the given type
 *
 * @m2m_ctx: m2m context assigned to the instance given by struct &v4l2_m2m_ctx
 * @type: type of the V4L2 buffer, as defined by enum &v4l2_buf_type
 */
struct vb2_queue *v4l2_m2m_get_vq(struct v4l2_m2m_ctx *m2m_ctx,
				       enum v4l2_buf_type type);

/**
 * 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 given by struct &v4l2_m2m_ctx
 *
 * 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.
 *
 * If a queue is buffered (for example a decoder hardware ringbuffer that has
 * to be drained before doing streamoff), allow scheduling without v4l2 buffers
 * on that queue.
 *
 * 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.
 */
void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx *m2m_ctx);

/**
 * v4l2_m2m_job_finish() - inform the framework that a job has been finished
 * and have it clean up
 *
 * @m2m_dev: opaque pointer to the internal data to handle M2M context
 * @m2m_ctx: m2m context assigned to the instance given by struct &v4l2_m2m_ctx
 *
 * 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 &v4l2_m2m_ops->device_run
 * callback has been called on the driver. To prevent recursion, it should
 * not be called directly from the &v4l2_m2m_ops->device_run callback though.
 */
void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
			 struct v4l2_m2m_ctx *m2m_ctx);

/**
 * v4l2_m2m_buf_done_and_job_finish() - return source/destination buffers with
 * state and inform the framework that a job has been finished and have it
 * clean up
 *
 * @m2m_dev: opaque pointer to the internal data to handle M2M context
 * @m2m_ctx: m2m context assigned to the instance given by struct &v4l2_m2m_ctx
 * @state: vb2 buffer state passed to v4l2_m2m_buf_done().
 *
 * Drivers that set V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF must use this
 * function instead of job_finish() to take held buffers into account. It is
 * optional for other drivers.
 *
 * This function removes the source buffer from the ready list and returns
 * it with the given state. The same is done for the destination buffer, unless
 * it is marked 'held'. In that case the buffer is kept on the ready list.
 *
 * After that the job is finished (see job_finish()).
 *
 * This allows for multiple output buffers to be used to fill in a single
 * capture buffer. This is typically used by stateless decoders where
 * multiple e.g. H.264 slices contribute to a single decoded frame.
 */
void v4l2_m2m_buf_done_and_job_finish(struct v4l2_m2m_dev *m2m_dev,
				      struct v4l2_m2m_ctx *m2m_ctx,
				      enum vb2_buffer_state state);

static inline void
v4l2_m2m_buf_done(struct vb2_v4l2_buffer *buf, enum vb2_buffer_state state)
{
	vb2_buffer_done(&buf->vb2_buf, state);
}

/**
 * v4l2_m2m_clear_state() - clear encoding/decoding state
 *
 * @m2m_ctx: m2m context assigned to the instance given by struct &v4l2_m2m_ctx
 */
static inline void
v4l2_m2m_clear_state(struct v4l2_m2m_ctx *m2m_ctx)
{
	m2m_ctx->next_buf_last = false;
	m2m_ctx->is_draining = false;
	m2m_ctx->has_stopped = false;
}

/**
 * v4l2_m2m_mark_stopped() - set current encoding/decoding state as stopped
 *
 * @m2m_ctx: m2m context assigned to the instance given by struct &v4l2_m2m_ctx
 */
static inline void
v4l2_m2m_mark_stopped(struct v4l2_m2m_ctx *m2m_ctx)
{
	m2m_ctx->next_buf_last = false;
	m2m_ctx->is_draining = false;
	m2m_ctx->has_stopped = true;
}

/**
 * v4l2_m2m_dst_buf_is_last() - return the current encoding/decoding session
 * draining management state of next queued capture buffer
 *
 * This last capture buffer should be tagged with V4L2_BUF_FLAG_LAST to notify
 * the end of the capture session.
 *
 * @m2m_ctx: m2m context assigned to the instance given by struct &v4l2_m2m_ctx
 */
static inline bool
v4l2_m2m_dst_buf_is_last(struct v4l2_m2m_ctx *m2m_ctx)
{
	return m2m_ctx->is_draining && m2m_ctx->next_buf_last;
}

/**
 * v4l2_m2m_has_stopped() - return the current encoding/decoding session
 * stopped state
 *
 * @m2m_ctx: m2m context assigned to the instance given by struct &v4l2_m2m_ctx
 */
static inline bool
v4l2_m2m_has_stopped(struct v4l2_m2m_ctx *m2m_ctx)
{
	return m2m_ctx->has_stopped;
}

/**
 * v4l2_m2m_is_last_draining_src_buf() - return the output buffer draining
 * state in the current encoding/decoding session
 *
 * This will identify the last output buffer queued before a session stop
 * was required, leading to an actual encoding/decoding session stop state
 * in the encoding/decoding process after being processed.
 *
 * @m2m_ctx: m2m context assigned to the instance given by struct &v4l2_m2m_ctx
 * @vbuf: pointer to struct &v4l2_buffer
 */
static inline bool
v4l2_m2m_is_last_draining_src_buf(struct v4l2_m2m_ctx *m2m_ctx,
				  struct vb2_v4l2_buffer *vbuf)
{
	return m2m_ctx->is_draining && vbuf == m2m_ctx->last_src_buf;
}

/**
 * v4l2_m2m_last_buffer_done() - marks the buffer with LAST flag and DONE
 *
 * @m2m_ctx: m2m context assigned to the instance given by struct &v4l2_m2m_ctx
 * @vbuf: pointer to struct &v4l2_buffer
 */
void v4l2_m2m_last_buffer_done(struct v4l2_m2m_ctx *m2m_ctx,
			       struct vb2