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 * Return a scatterlist for some page-aligned vmalloc()'ed memory 29 * block (NULL on errors). Memory for the scatterlist is allocated 30 * using kmalloc. The caller must free the memory. 31 */ 32 struct scatterlist *videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages); 33 34 /* 35 * Return a scatterlist for a an array of userpages (NULL on errors). 36 * Memory for the scatterlist is allocated using kmalloc. The caller 37 * must free the memory. 38 */ 39 struct scatterlist *videobuf_pages_to_sg(struct page **pages, int nr_pages, 40 int offset); 41 42 /* --------------------------------------------------------------------- */ 43 44 /* 45 * A small set of helper functions to manage buffers (both userland 46 * and kernel) for DMA. 47 * 48 * videobuf_dma_init_*() 49 * creates a buffer. The userland version takes a userspace 50 * pointer + length. The kernel version just wants the size and 51 * does memory allocation too using vmalloc_32(). 52 * 53 * videobuf_dma_*() 54 * see Documentation/PCI/PCI-DMA-mapping.txt, these functions to 55 * basically the same. The map function does also build a 56 * scatterlist for the buffer (and unmap frees it ...) 57 * 58 * videobuf_dma_free() 59 * no comment ... 60 * 61 */ 62 63 struct videobuf_dmabuf { 64 u32 magic; 65 66 /* for userland buffer */ 67 int offset; 68 struct page **pages; 69 70 /* for kernel buffers */ 71 void *vmalloc; 72 73 /* for overlay buffers (pci-pci dma) */ 74 dma_addr_t bus_addr; 75 76 /* common */ 77 struct scatterlist *sglist; 78 int sglen; 79 int nr_pages; 80 int direction; 81 }; 82 83 struct videobuf_dma_sg_memory { 84 u32 magic; 85 86 /* for mmap'ed buffers */ 87 struct videobuf_dmabuf dma; 88 }; 89 90 void videobuf_dma_init(struct videobuf_dmabuf *dma); 91 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction, 92 unsigned long data, unsigned long size); 93 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction, 94 int nr_pages); 95 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction, 96 dma_addr_t addr, int nr_pages); 97 int videobuf_dma_free(struct videobuf_dmabuf *dma); 98 99 int videobuf_dma_map(struct videobuf_queue *q, struct videobuf_dmabuf *dma); 100 int videobuf_dma_unmap(struct videobuf_queue *q, struct videobuf_dmabuf *dma); 101 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf); 102 103 void *videobuf_sg_alloc(size_t size); 104 105 void videobuf_queue_sg_init(struct videobuf_queue *q, 106 const struct videobuf_queue_ops *ops, 107 struct device *dev, 108 spinlock_t *irqlock, 109 enum v4l2_buf_type type, 110 enum v4l2_field field, 111 unsigned int msize, 112 void *priv); 113 114 /*FIXME: these variants are used only on *-alsa code, where videobuf is 115 * used without queue 116 */ 117 int videobuf_sg_dma_map(struct device *dev, struct videobuf_dmabuf *dma); 118 int videobuf_sg_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma); 119 120 #endif /* _VIDEOBUF_DMA_SG_H */ 121 122