[media] v4l: add videobuf2 Video for Linux 2 driver framework

Videobuf2 is a Video for Linux 2 API-compatible driver framework for
multimedia devices. It acts as an intermediate layer between userspace
applications and device drivers. It also provides low-level, modular
memory management functions for drivers.

Videobuf2 eases driver development, reduces drivers' code size and aids in
proper and consistent implementation of V4L2 API in drivers.

Videobuf2 memory management backend is fully modular. This allows custom
memory management routines for devices and platforms with non-standard
memory management requirements to be plugged in, without changing the
high-level buffer management functions and API.

The framework provides:
- implementations of streaming I/O V4L2 ioctls and file operations
- high-level video buffer, video queue and state management functions
- video buffer memory allocation and management

Signed-off-by: Pawel Osciak <p.osciak@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
CC: Pawel Osciak <pawel@osciak.com>
Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 371 insertions, 0 deletions

diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
new file mode 100644
index 000000000000..1dafac05ce1a
--- /dev/null
+++ b/include/media/videobuf2-core.h
@@ -0,0 +1,371 @@
+/*
+ * videobuf2-core.h - V4L2 driver helper framework
+ *
+ * Copyright (C) 2010 Samsung Electronics
+ *
+ * Author: Pawel Osciak <p.osciak@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.
+ */
+#ifndef _MEDIA_VIDEOBUF2_CORE_H
+#define _MEDIA_VIDEOBUF2_CORE_H
+
+#include <linux/mm_types.h>
+#include <linux/mutex.h>
+#include <linux/poll.h>
+#include <linux/videodev2.h>
+
+struct vb2_alloc_ctx;
+
+/**
+ * struct vb2_mem_ops - memory handling/memory allocator operations
+ * @alloc:	allocate video memory and, optionally, allocator private data,
+ *		return NULL on failure or a pointer to allocator private,
+ *		per-buffer data on success; the returned private structure
+ *		will then be passed as buf_priv argument to other ops in this
+ *		structure
+ * @put:	inform the allocator that the buffer will no longer be used;
+ *		usually will result in the allocator freeing the buffer (if
+ *		no other users of this buffer are present); the buf_priv
+ *		argument is the allocator private per-buffer structure
+ *		previously returned from the alloc callback
+ * @get_userptr: acquire userspace memory for a hardware operation; used for
+ *		 USERPTR memory types; vaddr is the address passed to the
+ *		 videobuf layer when queuing a video buffer of USERPTR type;
+ *		 should return an allocator private per-buffer structure
+ *		 associated with the buffer on success, NULL on failure;
+ *		 the returned private structure will then be passed as buf_priv
+ *		 argument to other ops in this structure
+ * @put_userptr: inform the allocator that a USERPTR buffer will no longer
+ *		 be used
+ * @vaddr:	return a kernel virtual address to a given memory buffer
+ *		associated with the passed private structure or NULL if no
+ *		such mapping exists
+ * @cookie:	return allocator specific cookie for a given memory buffer
+ *		associated with the passed private structure or NULL if not
+ *		available
+ * @num_users:	return the current number of users of a memory buffer;
+ *		return 1 if the videobuf layer (or actually the driver using
+ *		it) is the only user
+ * @mmap:	setup a userspace mapping for a given memory buffer under
+ *		the provided virtual memory region
+ *
+ * Required ops for USERPTR types: get_userptr, put_userptr.
+ * Required ops for MMAP types: alloc, put, num_users, mmap.
+ */
+struct vb2_mem_ops {
+	void		*(*alloc)(void *alloc_ctx, unsigned long size);
+	void		(*put)(void *buf_priv);
+
+	void		*(*get_userptr)(void *alloc_ctx, unsigned long vaddr,
+					unsigned long size, int write);
+	void		(*put_userptr)(void *buf_priv);
+
+	void		*(*vaddr)(void *buf_priv);
+	void		*(*cookie)(void *buf_priv);
+
+	unsigned int	(*num_users)(void *buf_priv);
+
+	int		(*mmap)(void *buf_priv, struct vm_area_struct *vma);
+};
+
+struct vb2_plane {
+	void			*mem_priv;
+	int			mapped:1;
+};
+
+/**
+ * enum vb2_io_modes - queue access methods
+ * @VB2_MMAP:		driver supports MMAP with streaming API
+ * @VB2_USERPTR:	driver supports USERPTR with streaming API
+ * @VB2_READ:		driver supports read() style access
+ * @VB2_WRITE:		driver supports write() style access
+ */
+enum vb2_io_modes {
+	VB2_MMAP	= (1 << 0),
+	VB2_USERPTR	= (1 << 1),
+	VB2_READ	= (1 << 2),
+	VB2_WRITE	= (1 << 3),
+};
+
+/**
+ * enum vb2_fileio_flags - flags for selecting a mode of the file io emulator,
+ * by default the 'streaming' style is used by the file io emulator
+ * @VB2_FILEIO_READ_ONCE:	report EOF after reading the first buffer
+ * @VB2_FILEIO_WRITE_IMMEDIATELY:	queue buffer after each write() call
+ */
+enum vb2_fileio_flags {
+	VB2_FILEIO_READ_ONCE		= (1 << 0),
+	VB2_FILEIO_WRITE_IMMEDIATELY	= (1 << 1),
+};
+
+/**
+ * enum vb2_buffer_state - current video buffer state
+ * @VB2_BUF_STATE_DEQUEUED:	buffer under userspace control
+ * @VB2_BUF_STATE_QUEUED:	buffer queued in videobuf, but not in driver
+ * @VB2_BUF_STATE_ACTIVE:	buffer queued in driver and possibly used
+ *				in a hardware operation
+ * @VB2_BUF_STATE_DONE:		buffer returned from driver to videobuf, but
+ *				not yet dequeued to userspace
+ * @VB2_BUF_STATE_ERROR:	same as above, but the operation on the buffer
+ *				has ended with an error, which will be reported
+ *				to the userspace when it is dequeued
+ */
+enum vb2_buffer_state {
+	VB2_BUF_STATE_DEQUEUED,
+	VB2_BUF_STATE_QUEUED,
+	VB2_BUF_STATE_ACTIVE,
+	VB2_BUF_STATE_DONE,
+	VB2_BUF_STATE_ERROR,
+};
+
+struct vb2_queue;
+
+/**
+ * struct vb2_buffer - represents a video buffer
+ * @v4l2_buf:		struct v4l2_buffer associated with this buffer; can
+ *			be read by the driver and relevant entries can be
+ *			changed by the driver in case of CAPTURE types
+ *			(such as timestamp)
+ * @v4l2_planes:	struct v4l2_planes associated with this buffer; can
+ *			be read by the driver and relevant entries can be
+ *			changed by the driver in case of CAPTURE types
+ *			(such as bytesused); NOTE that even for single-planar
+ *			types, the v4l2_planes[0] struct should be used
+ *			instead of v4l2_buf for filling bytesused - drivers
+ *			should use the vb2_set_plane_payload() function for that
+ * @vb2_queue:		the queue to which this driver belongs
+ * @num_planes:		number of planes in the buffer
+ *			on an internal driver queue
+ * @state:		current buffer state; do not change
+ * @queued_entry:	entry on the queued buffers list, which holds all
+ *			buffers queued from userspace
+ * @done_entry:		entry on the list that stores all buffers ready to
+ *			be dequeued to userspace
+ * @planes:		private per-plane information; do not change
+ * @num_planes_mapped:	number of mapped planes; do not change
+ */
+struct vb2_buffer {
+	struct v4l2_buffer	v4l2_buf;
+	struct v4l2_plane	v4l2_planes[VIDEO_MAX_PLANES];
+
+	struct vb2_queue	*vb2_queue;
+
+	unsigned int		num_planes;
+
+/* Private: internal use only */
+	enum vb2_buffer_state	state;
+
+	struct list_head	queued_entry;
+	struct list_head	done_entry;
+
+	struct vb2_plane	planes[VIDEO_MAX_PLANES];
+	unsigned int		num_planes_mapped;
+};
+
+/**
+ * struct vb2_ops - driver-specific callbacks
+ *
+ * @queue_setup:	called from a VIDIOC_REQBUFS handler, before
+ *			memory allocation; driver should return the required
+ *			number of buffers in num_buffers, the required number
+ *			of planes per buffer in num_planes; the size of each
+ *			plane should be set in the sizes[] array and optional
+ *			per-plane allocator specific context in alloc_ctxs[]
+ *			array
+ * @wait_prepare:	release any locks taken while calling vb2 functions;
+ *			it is called before an ioctl needs to wait for a new
+ *			buffer to arrive; required to avoid a deadlock in
+ *			blocking access type
+ * @wait_finish:	reacquire all locks released in the previous callback;
+ *			required to continue operation after sleeping while
+ *			waiting for a new buffer to arrive
+ * @buf_init:		called once after allocating a buffer (in MMAP case)
+ *			or after acquiring a new USERPTR buffer; drivers may
+ *			perform additional buffer-related initialization;
+ *			initialization failure (return != 0) will prevent
+ *			queue setup from completing successfully; optional
+ * @buf_prepare:	called every time the buffer is queued from userspace;
+ *			drivers may perform any initialization required before
+ *			each hardware operation in this callback;
+ *			if an error is returned, the buffer will not be queued
+ *			in driver; optional
+ * @buf_finish:		called before every dequeue of the buffer back to
+ *			userspace; drivers may perform any operations required
+ *			before userspace accesses the buffer; optional
+ * @buf_cleanup:	called once before the buffer is freed; drivers may
+ *			perform any additional cleanup; optional
+ * @start_streaming:	called once before entering 'streaming' state; enables
+ *			driver to receive buffers over buf_queue() callback
+ * @stop_streaming:	called when 'streaming' state must be disabled; driver
+ *			should stop any DMA transactions or wait until they
+ *			finish and give back all buffers it got from buf_queue()
+ *			callback; may use vb2_wait_for_all_buffers() function
+ * @buf_queue:		passes buffer vb to the driver; driver may start
+ *			hardware operation on this buffer; driver should give
+ *			the buffer back by calling vb2_buffer_done() function
+ */
+struct vb2_ops {
+	int (*queue_setup)(struct vb2_queue *q, unsigned int *num_buffers,
+			   unsigned int *num_planes, unsigned long sizes[],
+			   void *alloc_ctxs[]);
+
+	void (*wait_prepare)(struct vb2_queue *q);
+	void (*wait_finish)(struct vb2_queue *q);
+
+	int (*buf_init)(struct vb2_buffer *vb);
+	int (*buf_prepare)(struct vb2_buffer *vb);
+	int (*buf_finish)(struct vb2_buffer *vb);
+	void (*buf_cleanup)(struct vb2_buffer *vb);
+
+	int (*start_streaming)(struct vb2_queue *q);
+	int (*stop_streaming)(struct vb2_queue *q);
+
+	void (*buf_queue)(struct vb2_buffer *vb);
+};
+
+/**
+ * struct vb2_queue - a videobuf queue
+ *
+ * @type:	queue type (see V4L2_BUF_TYPE_* in linux/videodev2.h
+ * @io_modes:	supported io methods (see vb2_io_modes enum)
+ * @io_flags:	additional io flags (see vb2_fileio_flags enum)
+ * @ops:	driver-specific callbacks
+ * @mem_ops:	memory allocator specific callbacks
+ * @drv_priv:	driver private data
+ * @buf_struct_size: size of the driver-specific buffer structure;
+ *		"0" indicates the driver doesn't want to use a custom buffer
+ *		structure type, so sizeof(struct vb2_buffer) will is used
+ *
+ * @memory:	current memory type used
+ * @bufs:	videobuf buffer structures
+ * @num_buffers: number of allocated/used buffers
+ * @queued_list: list of buffers currently queued from userspace
+ * @queued_count: number of buffers owned by the driver
+ * @done_list:	list of buffers ready to be dequeued to userspace
+ * @done_lock:	lock to protect done_list list
+ * @done_wq:	waitqueue for processes waiting for buffers ready to be dequeued
+ * @alloc_ctx:	memory type/allocator-specific contexts for each plane
+ * @streaming:	current streaming state
+ */
+struct vb2_queue {
+	enum v4l2_buf_type		type;
+	unsigned int			io_modes;
+	unsigned int			io_flags;
+
+	const struct vb2_ops		*ops;
+	const struct vb2_mem_ops	*mem_ops;
+	void				*drv_priv;
+	unsigned int			buf_struct_size;
+
+/* private: internal use only */
+	enum v4l2_memory		memory;
+	struct vb2_buffer		*bufs[VIDEO_MAX_FRAME];
+	unsigned int			num_buffers;
+
+	struct list_head		queued_list;
+
+	atomic_t			queued_count;
+	struct list_head		done_list;
+	spinlock_t			done_lock;
+	wait_queue_head_t		done_wq;
+
+	void				*alloc_ctx[VIDEO_MAX_PLANES];
+
+	unsigned int			streaming:1;
+};
+
+void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no);
+void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no);
+
+void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state);
+int vb2_wait_for_all_buffers(struct vb2_queue *q);
+
+int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b);
+int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req);
+
+int vb2_queue_init(struct vb2_queue *q);
+
+void vb2_queue_release(struct vb2_queue *q);
+
+int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b);
+int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking);
+
+int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type);
+int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type);
+
+int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma);
+unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait);
+
+/**
+ * vb2_is_streaming() - return streaming status of the queue
+ * @q:		videobuf queue
+ */
+static inline bool vb2_is_streaming(struct vb2_queue *q)
+{
+	return q->streaming;
+}
+
+/**
+ * vb2_is_busy() - return busy status of the queue
+ * @q:		videobuf queue
+ *
+ * This function checks if queue has any buffers allocated.
+ */
+static inline bool vb2_is_busy(struct vb2_queue *q)
+{
+	return (q->num_buffers > 0);
+}
+
+/**
+ * vb2_get_drv_priv() - return driver private data associated with the queue
+ * @q:		videobuf queue
+ */
+static inline void *vb2_get_drv_priv(struct vb2_queue *q)
+{
+	return q->drv_priv;
+}
+
+/**
+ * vb2_set_plane_payload() - set bytesused for the plane plane_no
+ * @vb:		buffer for which plane payload should be set
+ * @plane_no:	plane number for which payload should be set
+ * @size:	payload in bytes
+ */
+static inline void vb2_set_plane_payload(struct vb2_buffer *vb,
+				 unsigned int plane_no, unsigned long size)
+{
+	if (plane_no < vb->num_planes)
+		vb->v4l2_planes[plane_no].bytesused = size;
+}
+
+/**
+ * vb2_get_plane_payload() - set bytesused for the plane plane_no
+ * @vb:		buffer for which plane payload should be set
+ * @plane_no:	plane number for which payload should be set
+ * @size:	payload in bytes
+ */
+static inline unsigned long vb2_get_plane_payload(struct vb2_buffer *vb,
+				 unsigned int plane_no)
+{
+	if (plane_no < vb->num_planes)
+		return vb->v4l2_planes[plane_no].bytesused;
+	return 0;
+}
+
+/**
+ * vb2_plane_size() - return plane size in bytes
+ * @vb:		buffer for which plane size should be returned
+ * @plane_no:	plane number for which size should be returned
+ */
+static inline unsigned long
+vb2_plane_size(struct vb2_buffer *vb, unsigned int plane_no)
+{
+	if (plane_no < vb->num_planes)
+		return vb->v4l2_planes[plane_no].length;
+	return 0;
+}
+
+#endif /* _MEDIA_VIDEOBUF2_CORE_H */