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 <asm/bug.h> 14 15 /* 16 * Generic direct DMA implementation 17 * 18 * This implementation supports a per-device offset that can be applied if 19 * the address at which memory is visible to devices is not 0. Platform code 20 * can set archdata.dma_data to an unsigned long holding the offset. By 21 * default the offset is PCI_DRAM_OFFSET. 22 */ 23 24 static unsigned long get_dma_direct_offset(struct device *dev) 25 { 26 if (likely(dev)) 27 return (unsigned long)dev->archdata.dma_data; 28 29 return PCI_DRAM_OFFSET; /* FIXME Not sure if is correct */ 30 } 31 32 #define NOT_COHERENT_CACHE 33 34 static void *dma_direct_alloc_coherent(struct device *dev, size_t size, 35 dma_addr_t *dma_handle, gfp_t flag) 36 { 37 #ifdef NOT_COHERENT_CACHE 38 return consistent_alloc(flag, size, dma_handle); 39 #else 40 void *ret; 41 struct page *page; 42 int node = dev_to_node(dev); 43 44 /* ignore region specifiers */ 45 flag &= ~(__GFP_HIGHMEM); 46 47 page = alloc_pages_node(node, flag, get_order(size)); 48 if (page == NULL) 49 return NULL; 50 ret = page_address(page); 51 memset(ret, 0, size); 52 *dma_handle = virt_to_phys(ret) + get_dma_direct_offset(dev); 53 54 return ret; 55 #endif 56 } 57 58 static void dma_direct_free_coherent(struct device *dev, size_t size, 59 void *vaddr, dma_addr_t dma_handle) 60 { 61 #ifdef NOT_COHERENT_CACHE 62 consistent_free(size, vaddr); 63 #else 64 free_pages((unsigned long)vaddr, get_order(size)); 65 #endif 66 } 67 68 static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, 69 int nents, enum dma_data_direction direction, 70 struct dma_attrs *attrs) 71 { 72 struct scatterlist *sg; 73 int i; 74 75 /* FIXME this part of code is untested */ 76 for_each_sg(sgl, sg, nents, i) { 77 sg->dma_address = sg_phys(sg) + get_dma_direct_offset(dev); 78 __dma_sync(page_to_phys(sg_page(sg)) + sg->offset, 79 sg->length, direction); 80 } 81 82 return nents; 83 } 84 85 static void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sg, 86 int nents, enum dma_data_direction direction, 87 struct dma_attrs *attrs) 88 { 89 } 90 91 static int dma_direct_dma_supported(struct device *dev, u64 mask) 92 { 93 return 1; 94 } 95 96 static inline dma_addr_t dma_direct_map_page(struct device *dev, 97 struct page *page, 98 unsigned long offset, 99 size_t size, 100 enum dma_data_direction direction, 101 struct dma_attrs *attrs) 102 { 103 __dma_sync(page_to_phys(page) + offset, size, direction); 104 return page_to_phys(page) + offset + get_dma_direct_offset(dev); 105 } 106 107 static inline void dma_direct_unmap_page(struct device *dev, 108 dma_addr_t dma_address, 109 size_t size, 110 enum dma_data_direction direction, 111 struct dma_attrs *attrs) 112 { 113 /* There is not necessary to do cache cleanup 114 * 115 * phys_to_virt is here because in __dma_sync_page is __virt_to_phys and 116 * dma_address is physical address 117 */ 118 __dma_sync(dma_address, size, direction); 119 } 120 121 static inline void 122 dma_direct_sync_single_for_cpu(struct device *dev, 123 dma_addr_t dma_handle, size_t size, 124 enum dma_data_direction direction) 125 { 126 /* 127 * It's pointless to flush the cache as the memory segment 128 * is given to the CPU 129 */ 130 131 if (direction == DMA_FROM_DEVICE) 132 __dma_sync(dma_handle, size, direction); 133 } 134 135 static inline void 136 dma_direct_sync_single_for_device(struct device *dev, 137 dma_addr_t dma_handle, size_t size, 138 enum dma_data_direction direction) 139 { 140 /* 141 * It's pointless to invalidate the cache if the device isn't 142 * supposed to write to the relevant region 143 */ 144 145 if (direction == DMA_TO_DEVICE) 146 __dma_sync(dma_handle, size, direction); 147 } 148 149 static inline void 150 dma_direct_sync_sg_for_cpu(struct device *dev, 151 struct scatterlist *sgl, int nents, 152 enum dma_data_direction direction) 153 { 154 struct scatterlist *sg; 155 int i; 156 157 /* FIXME this part of code is untested */ 158 if (direction == DMA_FROM_DEVICE) 159 for_each_sg(sgl, sg, nents, i) 160 __dma_sync(sg->dma_address, sg->length, direction); 161 } 162 163 static inline void 164 dma_direct_sync_sg_for_device(struct device *dev, 165 struct scatterlist *sgl, int nents, 166 enum dma_data_direction direction) 167 { 168 struct scatterlist *sg; 169 int i; 170 171 /* FIXME this part of code is untested */ 172 if (direction == DMA_TO_DEVICE) 173 for_each_sg(sgl, sg, nents, i) 174 __dma_sync(sg->dma_address, sg->length, direction); 175 } 176 177 struct dma_map_ops dma_direct_ops = { 178 .alloc_coherent = dma_direct_alloc_coherent, 179 .free_coherent = dma_direct_free_coherent, 180 .map_sg = dma_direct_map_sg, 181 .unmap_sg = dma_direct_unmap_sg, 182 .dma_supported = dma_direct_dma_supported, 183 .map_page = dma_direct_map_page, 184 .unmap_page = dma_direct_unmap_page, 185 .sync_single_for_cpu = dma_direct_sync_single_for_cpu, 186 .sync_single_for_device = dma_direct_sync_single_for_device, 187 .sync_sg_for_cpu = dma_direct_sync_sg_for_cpu, 188 .sync_sg_for_device = dma_direct_sync_sg_for_device, 189 }; 190 EXPORT_SYMBOL(dma_direct_ops); 191 192 /* Number of entries preallocated for DMA-API debugging */ 193 #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16) 194 195 static int __init dma_init(void) 196 { 197 dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES); 198 199 return 0; 200 } 201 fs_initcall(dma_init); 202