1 /* 2 * helper functions for SG DMA video4linux capture buffers 3 * 4 * The functions expect the hardware being able to scatter gather 5 * (i.e. the buffers are not linear in physical memory, but fragmented 6 * into PAGE_SIZE chunks). They also assume the driver does not need 7 * to touch the video data. 8 * 9 * (c) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org> 10 * 11 * Highly based on video-buf written originally by: 12 * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org> 13 * (c) 2006 Mauro Carvalho Chehab, <mchehab@infradead.org> 14 * (c) 2006 Ted Walther and John Sokol 15 * 16 * This program is free software; you can redistribute it and/or modify 17 * it under the terms of the GNU General Public License as published by 18 * the Free Software Foundation; either version 2 19 */ 20 #ifndef _VIDEOBUF_DMA_SG_H 21 #define _VIDEOBUF_DMA_SG_H 22 23 #include <media/videobuf-core.h> 24 25 /* --------------------------------------------------------------------- */ 26 27 /* 28 * A small set of helper functions to manage buffers (both userland 29 * and kernel) for DMA. 30 * 31 * videobuf_dma_init_*() 32 * creates a buffer. The userland version takes a userspace 33 * pointer + length. The kernel version just wants the size and 34 * does memory allocation too using vmalloc_32(). 35 * 36 * videobuf_dma_*() 37 * see Documentation/DMA-API-HOWTO.txt, these functions to 38 * basically the same. The map function does also build a 39 * scatterlist for the buffer (and unmap frees it ...) 40 * 41 * videobuf_dma_free() 42 * no comment ... 43 * 44 */ 45 46 struct videobuf_dmabuf { 47 u32 magic; 48 49 /* for userland buffer */ 50 int offset; 51 size_t size; 52 struct page **pages; 53 54 /* for kernel buffers */ 55 void *vaddr; 56 struct page **vaddr_pages; 57 dma_addr_t *dma_addr; 58 struct device *dev; 59 60 /* for overlay buffers (pci-pci dma) */ 61 dma_addr_t bus_addr; 62 63 /* common */ 64 struct scatterlist *sglist; 65 int sglen; 66 int nr_pages; 67 int direction; 68 }; 69 70 struct videobuf_dma_sg_memory { 71 u32 magic; 72 73 /* for mmap'ed buffers */ 74 struct videobuf_dmabuf dma; 75 }; 76 77 /* 78 * Scatter-gather DMA buffer API. 79 * 80 * These functions provide a simple way to create a page list and a 81 * scatter-gather list from a kernel, userspace of physical address and map the 82 * memory for DMA operation. 83 * 84 * Despite the name, this is totally unrelated to videobuf, except that 85 * videobuf-dma-sg uses the same API internally. 86 */ 87 void videobuf_dma_init(struct videobuf_dmabuf *dma); 88 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction, 89 unsigned long data, unsigned long size); 90 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction, 91 int nr_pages); 92 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction, 93 dma_addr_t addr, int nr_pages); 94 int videobuf_dma_free(struct videobuf_dmabuf *dma); 95 96 int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma); 97 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma); 98 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf); 99 100 void *videobuf_sg_alloc(size_t size); 101 102 void videobuf_queue_sg_init(struct videobuf_queue *q, 103 const struct videobuf_queue_ops *ops, 104 struct device *dev, 105 spinlock_t *irqlock, 106 enum v4l2_buf_type type, 107 enum v4l2_field field, 108 unsigned int msize, 109 void *priv, 110 struct mutex *ext_lock); 111 112 #endif /* _VIDEOBUF_DMA_SG_H */ 113 114