1 /* 2 * Copyright (C) 2009-2010 PetaLogix 3 * Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corporation 4 * 5 * Provide default implementations of the DMA mapping callbacks for 6 * directly mapped busses. 7 */ 8 9 #include <linux/device.h> 10 #include <linux/dma-mapping.h> 11 #include <linux/gfp.h> 12 #include <linux/dma-debug.h> 13 #include <linux/export.h> 14 #include <asm/bug.h> 15 #include <asm/cacheflush.h> 16 17 /* 18 * Generic direct DMA implementation 19 * 20 * This implementation supports a per-device offset that can be applied if 21 * the address at which memory is visible to devices is not 0. Platform code 22 * can set archdata.dma_data to an unsigned long holding the offset. By 23 * default the offset is PCI_DRAM_OFFSET. 24 */ 25 static inline void __dma_sync_page(unsigned long paddr, unsigned long offset, 26 size_t size, enum dma_data_direction direction) 27 { 28 switch (direction) { 29 case DMA_TO_DEVICE: 30 case DMA_BIDIRECTIONAL: 31 flush_dcache_range(paddr + offset, paddr + offset + size); 32 break; 33 case DMA_FROM_DEVICE: 34 invalidate_dcache_range(paddr + offset, paddr + offset + size); 35 break; 36 default: 37 BUG(); 38 } 39 } 40 41 static unsigned long get_dma_direct_offset(struct device *dev) 42 { 43 if (likely(dev)) 44 return (unsigned long)dev->archdata.dma_data; 45 46 return PCI_DRAM_OFFSET; /* FIXME Not sure if is correct */ 47 } 48 49 #define NOT_COHERENT_CACHE 50 51 static void *dma_direct_alloc_coherent(struct device *dev, size_t size, 52 dma_addr_t *dma_handle, gfp_t flag) 53 { 54 #ifdef NOT_COHERENT_CACHE 55 return consistent_alloc(flag, size, dma_handle); 56 #else 57 void *ret; 58 struct page *page; 59 int node = dev_to_node(dev); 60 61 /* ignore region specifiers */ 62 flag &= ~(__GFP_HIGHMEM); 63 64 page = alloc_pages_node(node, flag, get_order(size)); 65 if (page == NULL) 66 return NULL; 67 ret = page_address(page); 68 memset(ret, 0, size); 69 *dma_handle = virt_to_phys(ret) + get_dma_direct_offset(dev); 70 71 return ret; 72 #endif 73 } 74 75 static void dma_direct_free_coherent(struct device *dev, size_t size, 76 void *vaddr, dma_addr_t dma_handle) 77 { 78 #ifdef NOT_COHERENT_CACHE 79 consistent_free(size, vaddr); 80 #else 81 free_pages((unsigned long)vaddr, get_order(size)); 82 #endif 83 } 84 85 static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, 86 int nents, enum dma_data_direction direction, 87 struct dma_attrs *attrs) 88 { 89 struct scatterlist *sg; 90 int i; 91 92 /* FIXME this part of code is untested */ 93 for_each_sg(sgl, sg, nents, i) { 94 sg->dma_address = sg_phys(sg) + get_dma_direct_offset(dev); 95 __dma_sync_page(page_to_phys(sg_page(sg)), sg->offset, 96 sg->length, direction); 97 } 98 99 return nents; 100 } 101 102 static void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sg, 103 int nents, enum dma_data_direction direction, 104 struct dma_attrs *attrs) 105 { 106 } 107 108 static int dma_direct_dma_supported(struct device *dev, u64 mask) 109 { 110 return 1; 111 } 112 113 static inline dma_addr_t dma_direct_map_page(struct device *dev, 114 struct page *page, 115 unsigned long offset, 116 size_t size, 117 enum dma_data_direction direction, 118 struct dma_attrs *attrs) 119 { 120 __dma_sync_page(page_to_phys(page), offset, size, direction); 121 return page_to_phys(page) + offset + get_dma_direct_offset(dev); 122 } 123 124 static inline void dma_direct_unmap_page(struct device *dev, 125 dma_addr_t dma_address, 126 size_t size, 127 enum dma_data_direction direction, 128 struct dma_attrs *attrs) 129 { 130 /* There is not necessary to do cache cleanup 131 * 132 * phys_to_virt is here because in __dma_sync_page is __virt_to_phys and 133 * dma_address is physical address 134 */ 135 __dma_sync_page(dma_address, 0 , size, direction); 136 } 137 138 struct dma_map_ops dma_direct_ops = { 139 .alloc_coherent = dma_direct_alloc_coherent, 140 .free_coherent = dma_direct_free_coherent, 141 .map_sg = dma_direct_map_sg, 142 .unmap_sg = dma_direct_unmap_sg, 143 .dma_supported = dma_direct_dma_supported, 144 .map_page = dma_direct_map_page, 145 .unmap_page = dma_direct_unmap_page, 146 }; 147 EXPORT_SYMBOL(dma_direct_ops); 148 149 /* Number of entries preallocated for DMA-API debugging */ 150 #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16) 151 152 static int __init dma_init(void) 153 { 154 dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES); 155 156 return 0; 157 } 158 fs_initcall(dma_init); 159