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=34981
Reviewed-by: Ricardo Cerqueira <v4l@cerqueira.org>

1 files changed, 142 insertions, 0 deletions

diff --git a/include/media/videobuf-dma-sg.h b/include/media/videobuf-dma-sg.h
new file mode 100644
index 000000000000..62a3709905f3
--- /dev/null
+++ b/include/media/videobuf-dma-sg.h
@@ -0,0 +1,142 @@
+/*
+ * 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);
+