V4L/DVB (6251): Replace video-buf to a more generic approach

video-buf currently does two different tasks:

- Manages video buffers with a common code that allows
  implementing all the V4L2 different modes of buffering;

- Controls memory allocations

While the first task is generic, the second were written to support PCI DMA
Scatter/Gather needs. The original approach can't even work for those
video capture hardware that don't support scatter/gather.

I did one approach to make it more generic. While the approach worked
fine for vivi driver, it were not generic enough to handle USB needs.

This patch creates two different modules, one containing the generic
video buffer handling (videobuf-core) and another with PCI DMA S/G.
After this patch, it would be simpler to write an USB video-buf and a
non-SG DMA module.
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
http://thread.gmane.org/gmane.comp.video.video4linux/34978/focus=34981Reviewed-by: Ricardo Cerqueira <v4l@cerqueira.org>

include/media/videobuf-core.h

+/*
+ * 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/poll.h>
+#ifdef CONFIG_VIDEO_V4L1_COMPAT
+#include <linux/videodev.h>
+#endif
+#include <linux/videodev2.h>
+
+#define UNSET (-1U)
+
+
+struct videobuf_buffer;
+struct videobuf_queue;
+
+/* --------------------------------------------------------------------- */
+
+/*
+ * A small set of helper functions to manage video4linux buffers.
+ *
+ * struct videobuf_buffer holds the data structures used by the helper
+ * functions, additionally some commonly used fields for v4l buffers
+ * (width, height, lists, waitqueue) are in there.  That struct should
+ * be used as first element in the drivers buffer struct.
+ *
+ * about the mmap helpers (videobuf_mmap_*):
+ *
+ * The mmaper function allows to map any subset of contingous buffers.
+ * This includes one mmap() call for all buffers (which the original
+ * video4linux API uses) as well as one mmap() for every single buffer
+ * (which v4l2 uses).
+ *
+ * If there is a valid mapping for a buffer, buffer->baddr/bsize holds
+ * userspace address + size which can be feeded into the
+ * videobuf_dma_init_user function listed above.
+ *
+ */
+
+struct videobuf_mapping {
+	unsigned int count;
+	unsigned long start;
+	unsigned long end;
+	struct videobuf_queue *q;
+};
+
+enum videobuf_state {
+	STATE_NEEDS_INIT = 0,
+	STATE_PREPARED   = 1,
+	STATE_QUEUED     = 2,
+	STATE_ACTIVE     = 3,
+	STATE_DONE       = 4,
+	STATE_ERROR      = 5,
+	STATE_IDLE       = 6,
+};
+
+struct videobuf_buffer {
+	unsigned int            i;
+	u32                     magic;
+
+	/* info about the buffer */
+	unsigned int            width;
+	unsigned int            height;
+	unsigned int            bytesperline; /* use only if != 0 */
+	unsigned long           size;
+	unsigned int            input;
+	enum v4l2_field         field;
+	enum videobuf_state     state;
+	struct list_head        stream;  /* QBUF/DQBUF list */
+
+	/* touched by irq handler */
+	struct list_head        queue;
+	wait_queue_head_t       done;
+	unsigned int            field_count;
+	struct timeval          ts;
+
+	/* Memory type */
+	enum v4l2_memory        memory;
+
+	/* buffer size */
+	size_t                  bsize;
+
+	/* buffer offset (mmap + overlay) */
+	size_t                  boff;
+
+	/* buffer addr (userland ptr!) */
+	unsigned long           baddr;
+
+	/* Private pointer to allow specific methods to store their data */
+	int			privsize;
+	void                    *priv;
+};
+
+struct videobuf_queue_ops {
+	int (*buf_setup)(struct videobuf_queue *q,
+			 unsigned int *count, unsigned int *size);
+	int (*buf_prepare)(struct videobuf_queue *q,
+			   struct videobuf_buffer *vb,
+			   enum v4l2_field field);
+	void (*buf_queue)(struct videobuf_queue *q,
+			  struct videobuf_buffer *vb);
+	void (*buf_release)(struct videobuf_queue *q,
+			    struct videobuf_buffer *vb);
+};
+
+#define MAGIC_QTYPE_OPS	0x12261003
+
+/* Helper operations - device type dependent */
+struct videobuf_qtype_ops {
+	u32                     magic;
+
+	void* (*alloc)		(size_t size);
+	int (*iolock)		(struct videobuf_queue* q,
+				 struct videobuf_buffer *vb,
+				 struct v4l2_framebuffer *fbuf);
+	int (*mmap)		(struct videobuf_queue *q,
+				 unsigned int *count,
+				 unsigned int *size,
+				 enum v4l2_memory memory);
+	int (*sync)		(struct videobuf_queue* q,
+				 struct videobuf_buffer *buf);
+	int (*copy_to_user)	(struct videobuf_queue *q,
+				 char __user *data,
+				 size_t count,
+				 int nonblocking);
+	int (*copy_stream)	(struct videobuf_queue *q,
+				 char __user *data,
+				 size_t count,
+				 size_t pos,
+				 int vbihack,
+				 int nonblocking);
+	int (*mmap_free)	(struct videobuf_queue *q);
+	int (*mmap_mapper)	(struct videobuf_queue *q,
+				struct vm_area_struct *vma);
+	int (*is_mmapped)	(struct videobuf_buffer *buf);
+};
+
+struct videobuf_queue {
+	struct mutex               lock;
+	spinlock_t                 *irqlock;
+	void			   *dev; /* on pci, points to struct pci_dev */
+
+	enum v4l2_buf_type         type;
+	unsigned int               inputs; /* for V4L2_BUF_FLAG_INPUT */
+	unsigned int               msize;
+	enum v4l2_field            field;
+	enum v4l2_field            last;   /* for field=V4L2_FIELD_ALTERNATE */
+	struct videobuf_buffer     *bufs[VIDEO_MAX_FRAME];
+	struct videobuf_queue_ops  *ops;
+	struct videobuf_qtype_ops  *int_ops;
+
+	/* capture via mmap() + ioctl(QBUF/DQBUF) */
+	unsigned int               streaming;
+	struct list_head           stream;
+
+	/* capture via read() */
+	unsigned int               reading;
+	unsigned int               read_off;
+	struct videobuf_buffer     *read_buf;
+
+	/* driver private data */
+	void                       *priv_data;
+
+	/*FIXME: should be removed after completing the vb conversion */
+	void                       *priv_ops;
+};
+
+int videobuf_waiton(struct videobuf_buffer *vb, int non_blocking, int intr);
+int videobuf_iolock(struct videobuf_queue* q, struct videobuf_buffer *vb,
+		struct v4l2_framebuffer *fbuf);
+
+void *videobuf_alloc(struct videobuf_queue* q);
+
+void videobuf_queue_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);
+int  videobuf_queue_is_busy(struct videobuf_queue *q);
+void videobuf_queue_cancel(struct videobuf_queue *q);
+
+enum v4l2_field videobuf_next_field(struct videobuf_queue *q);
+int videobuf_reqbufs(struct videobuf_queue *q,
+		     struct v4l2_requestbuffers *req);
+int videobuf_querybuf(struct videobuf_queue *q, struct v4l2_buffer *b);
+int videobuf_qbuf(struct videobuf_queue *q,
+		  struct v4l2_buffer *b);
+int videobuf_dqbuf(struct videobuf_queue *q,
+		   struct v4l2_buffer *b, int nonblocking);
+#ifdef CONFIG_VIDEO_V4L1_COMPAT
+int videobuf_cgmbuf(struct videobuf_queue *q,
+		    struct video_mbuf *mbuf, int count);
+#endif
+int videobuf_streamon(struct videobuf_queue *q);
+int videobuf_streamoff(struct videobuf_queue *q);
+
+int videobuf_read_start(struct videobuf_queue *q);
+void videobuf_read_stop(struct videobuf_queue *q);
+ssize_t videobuf_read_stream(struct videobuf_queue *q,
+			     char __user *data, size_t count, loff_t *ppos,
+			     int vbihack, int nonblocking);
+ssize_t videobuf_read_one(struct videobuf_queue *q,
+			  char __user *data, size_t count, loff_t *ppos,
+			  int nonblocking);
+unsigned int videobuf_poll_stream(struct file *file,
+				  struct videobuf_queue *q,
+				  poll_table *wait);
+
+int videobuf_mmap_setup(struct videobuf_queue *q,
+			unsigned int bcount, unsigned int bsize,
+			enum v4l2_memory memory);
+int videobuf_mmap_free(struct videobuf_queue *q);
+int videobuf_mmap_mapper(struct videobuf_queue *q,
+			 struct vm_area_struct *vma);
+
+/* --------------------------------------------------------------------- */
+
+/*
+ * Local variables:
+ * c-basic-offset: 8
+ * End:
+ */

include/media/videobuf-dma-sg.h

+/*
+ * helper functions for PCI DMA video4linux capture buffers
+ *
+ * The functions expect the hardware being able to scatter gatter
+ * (i.e. the buffers are not linear in physical memory, but fragmented
+ * into PAGE_SIZE chunks).  They also assume the driver does not need
+ * to touch the video data.
+ *
+ * (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 <media/videobuf-core.h>
+
+/* --------------------------------------------------------------------- */
+
+/*
+ * Return a scatterlist for some page-aligned vmalloc()'ed memory
+ * block (NULL on errors).  Memory for the scatterlist is allocated
+ * using kmalloc.  The caller must free the memory.
+ */
+struct scatterlist* videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages);
+
+/*
+ * Return a scatterlist for a an array of userpages (NULL on errors).
+ * Memory for the scatterlist is allocated using kmalloc.  The caller
+ * must free the memory.
+ */
+struct scatterlist* videobuf_pages_to_sg(struct page **pages, int nr_pages,
+					 int offset);
+
+/* --------------------------------------------------------------------- */
+
+/*
+ * A small set of helper functions to manage buffers (both userland
+ * and kernel) for DMA.
+ *
+ * videobuf_dma_init_*()
+ *	creates a buffer.  The userland version takes a userspace
+ *	pointer + length.  The kernel version just wants the size and
+ *	does memory allocation too using vmalloc_32().
+ *
+ * videobuf_dma_*()
+ *	see Documentation/DMA-mapping.txt, these functions to
+ *	basically the same.  The map function does also build a
+ *	scatterlist for the buffer (and unmap frees it ...)
+ *
+ * videobuf_dma_free()
+ *	no comment ...
+ *
+ */
+
+struct videobuf_dmabuf {
+	u32                 magic;
+
+	/* for userland buffer */
+	int                 offset;
+	struct page         **pages;
+
+	/* for kernel buffers */
+	void                *vmalloc;
+
+	/* Stores the userspace pointer to vmalloc area */
+	void                *varea;
+
+	/* for overlay buffers (pci-pci dma) */
+	dma_addr_t          bus_addr;
+
+	/* common */
+	struct scatterlist  *sglist;
+	int                 sglen;
+	int                 nr_pages;
+	int                 direction;
+};
+
+struct videbuf_pci_sg_memory
+{
+	u32                 magic;
+
+	/* for mmap'ed buffers */
+	struct videobuf_mapping *map;
+	struct videobuf_dmabuf  dma;
+};
+
+/* FIXME: To be removed soon */
+typedef int (vb_map_sg_t)(void *dev, struct scatterlist *sglist, int nr_pages,
+					int direction);
+
+/* FIXME: To be removed soon */
+struct videobuf_dma_sg_ops
+{
+	vb_map_sg_t	*vb_map_sg;
+	vb_map_sg_t	*vb_dma_sync_sg;
+	vb_map_sg_t	*vb_unmap_sg;
+
+};
+
+void videobuf_dma_init(struct videobuf_dmabuf *dma);
+int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
+			   unsigned long data, unsigned long size);
+int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
+			     int nr_pages);
+int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
+			      dma_addr_t addr, int nr_pages);
+int videobuf_dma_free(struct videobuf_dmabuf *dma);
+
+int videobuf_dma_map(struct videobuf_queue* q,struct videobuf_dmabuf *dma);
+int videobuf_dma_sync(struct videobuf_queue* q,struct videobuf_dmabuf *dma);
+int videobuf_dma_unmap(struct videobuf_queue* q,struct videobuf_dmabuf *dma);
+struct videobuf_dmabuf *videobuf_to_dma (struct videobuf_buffer *buf);
+
+void *videobuf_pci_alloc (size_t size);
+
+void videobuf_queue_pci_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);
+
+	/*FIXME: these variants are used only on *-alsa code, where videobuf is
+	 * used without queue
+	 */
+int videobuf_pci_dma_map(struct pci_dev *pci,struct videobuf_dmabuf *dma);
+int videobuf_pci_dma_unmap(struct pci_dev *pci,struct videobuf_dmabuf *dma);
+
+/* FIXME: temporary routine for vivi and tm6000, while lacking implementation
+ * of videobuf-vmalloc
+ */
+void videobuf_set_pci_ops (struct videobuf_queue* q,
+				struct videobuf_dma_sg_ops *ops);
+