[PATCH] v4l: new videobuf helper module

This patch adds a helper module to manage pci dma buffers for video
frames.  I've recently started writing a driver for another frame
grabber / TV card chip and tried to separate out common code to avoid
duplicating code.  The bttv core update (next mail) depends this patch.

drivers/media/video/Makefile

@@ -25,7 +25,7 @@ O_TARGET := video.o
 # All of the (potential) objects that export symbols.
 # This list comes from 'grep -l EXPORT_SYMBOL *.[hc]'.
 
-export-objs     :=	i2c-old.o videodev.o bttv-if.o cpia.o
+export-objs     :=	i2c-old.o videodev.o bttv-if.o cpia.o video-buf.o
 
 list-multi	:=	bttv.o zoran.o
 bttv-objs	:=	bttv-driver.o bttv-cards.o bttv-if.o
@@ -35,7 +35,7 @@ obj-$(CONFIG_VIDEO_DEV) += videodev.o
 
 obj-$(CONFIG_BUS_I2C) += i2c-old.o
 obj-$(CONFIG_VIDEO_BT848) += bttv.o msp3400.o tvaudio.o \
-	tda7432.o tda9875.o tuner.o
+	tda7432.o tda9875.o tuner.o video-buf.o
 obj-$(CONFIG_SOUND_TVMIXER) += tvmixer.o
 
 obj-$(CONFIG_VIDEO_ZR36120) += zoran.o

drivers/media/video/video-buf.h

+/*
+ * generic helper functions for video4linux capture buffers, to handle
+ * memory management and PCI DMA.  Right now bttv + saa7134 use it.
+ *
+ * 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 (thus it is probably not useful for USB as
+ * data often must be uncompressed by the drivers).
+ * 
+ * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
+ *
+ * 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/videodev.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 locked iobuf (NULL on errors).  Memory
+ * for the scatterlist is allocated using kmalloc.  The caller must
+ * free the memory.
+ */
+struct scatterlist* videobuf_iobuf_to_sg(struct kiobuf *iobuf);
+
+/* --------------------------------------------------------------------- */
+
+/*
+ * A small set of helper functions to manage buffers (both userland
+ * and kernel) for DMA.
+ *
+ * videobuf_init_*_dmabuf()
+ *	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_pci_*_dmabuf()
+ *	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_free_dmabuf()
+ *	no comment ...
+ *
+ */
+
+struct videobuf_dmabuf {
+	/* for userland buffer */
+	struct kiobuf       *iobuf;
+
+	/* for kernel buffers */
+	void                *vmalloc;
+
+	/* common */
+	struct scatterlist  *sglist;
+	int                 sglen;
+	int                 nr_pages;
+	int                 direction;
+};
+
+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_pci_map(struct pci_dev *dev, struct videobuf_dmabuf *dma);
+int videobuf_dma_pci_sync(struct pci_dev *dev,
+			  struct videobuf_dmabuf *dma);
+int videobuf_dma_pci_unmap(struct pci_dev *dev, struct videobuf_dmabuf *dma);
+int videobuf_dma_free(struct videobuf_dmabuf *dma);
+
+/* --------------------------------------------------------------------- */
+
+/*
+ * 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_buffer;
+typedef void (*videobuf_buffer_free)(struct file *file,
+				     struct videobuf_buffer *vb);
+
+struct videobuf_mapping {
+	int count;
+	int highmem_ok;
+	unsigned long start;
+	unsigned long end;
+	struct videobuf_buffer **buflist;
+};
+
+#define VBUF_FIELD_EVEN  1
+#define VBUF_FIELD_ODD   2
+#define VBUF_FIELD_INTER 4
+
+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 {
+	int                     i;
+
+	/* info about the buffer */
+	int                     type;
+	int                     width;
+	int                     height;
+	long                    size;
+	int                     field;
+	enum videobuf_state     state;
+	struct videobuf_dmabuf  dma;
+	struct list_head        stream;  /* QBUF/DQBUF list */
+
+	/* for mmap'ed buffers */
+	unsigned long  boff;             /* buffer offset (mmap) */
+	unsigned long  bsize;            /* buffer size */
+	unsigned long  baddr;            /* buffer addr (userland ptr!) */
+	struct videobuf_mapping *map;
+	videobuf_buffer_free    free;
+
+	/* touched by irq handler */
+	struct list_head        queue;
+	wait_queue_head_t       done;
+	int                     field_count;
+#ifdef HAVE_V4L2
+	stamp_t                 ts;
+#endif
+};
+
+void* videobuf_alloc(int size, int type);
+int videobuf_waiton(struct videobuf_buffer *vb, int non_blocking, int intr);
+int videobuf_iolock(struct pci_dev *pci, struct videobuf_buffer *vb);
+#ifdef HAVE_V4L2
+void videobuf_status(struct v4l2_buffer *b, struct videobuf_buffer *vb);
+#endif
+
+int videobuf_mmap_setup(struct file *file, struct videobuf_buffer **buflist,
+			int msize, int bcount, int bsize, int type,
+			videobuf_buffer_free free);
+int videobuf_mmap_free(struct file *file, struct videobuf_buffer **buflist);
+int videobuf_mmap_mapper(struct vm_area_struct *vma,
+			 struct videobuf_buffer **buflist);
+
+/*
+ * Local variables:
+ * c-basic-offset: 8
+ * End:
+ */