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 <linux/bug.h> 15 16 /* 17 * Generic direct DMA implementation 18 * 19 * This implementation supports a per-device offset that can be applied if 20 * the address at which memory is visible to devices is not 0. Platform code 21 * can set archdata.dma_data to an unsigned long holding the offset. By 22 * default the offset is PCI_DRAM_OFFSET. 23 */ 24 25 static unsigned long get_dma_direct_offset(struct device *dev) 26 { 27 if (likely(dev)) 28 return (unsigned long)dev->archdata.dma_data; 29 30 return PCI_DRAM_OFFSET; /* FIXME Not sure if is correct */ 31 } 32 33 #define NOT_COHERENT_CACHE 34 35 static void *dma_direct_alloc_coherent(struct device *dev, size_t size, 36 dma_addr_t *dma_handle, gfp_t flag, 37 struct dma_attrs *attrs) 38 { 39 #ifdef NOT_COHERENT_CACHE 40 return consistent_alloc(flag, size, dma_handle); 41 #else 42 void *ret; 43 struct page *page; 44 int node = dev_to_node(dev); 45 46 /* ignore region specifiers */ 47 flag &= ~(__GFP_HIGHMEM); 48 49 page = alloc_pages_node(node, flag, get_order(size)); 50 if (page == NULL) 51 return NULL; 52 ret = page_address(page); 53 memset(ret, 0, size); 54 *dma_handle = virt_to_phys(ret) + get_dma_direct_offset(dev); 55 56 return ret; 57 #endif 58 } 59 60 static void dma_direct_free_coherent(struct device *dev, size_t size, 61 void *vaddr, dma_addr_t dma_handle, 62 struct dma_attrs *attrs) 63 { 64 #ifdef NOT_COHERENT_CACHE 65 consistent_free(size, vaddr); 66 #else 67 free_pages((unsigned long)vaddr, get_order(size)); 68 #endif 69 } 70 71 static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, 72 int nents, enum dma_data_direction direction, 73 struct dma_attrs *attrs) 74 { 75 struct scatterlist *sg; 76 int i; 77 78 /* FIXME this part of code is untested */ 79 for_each_sg(sgl, sg, nents, i) { 80 sg->dma_address = sg_phys(sg) + get_dma_direct_offset(dev); 81 __dma_sync(page_to_phys(sg_page(sg)) + sg->offset, 82 sg->length, direction); 83 } 84 85 return nents; 86 } 87 88 static void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sg, 89 int nents, enum dma_data_direction direction, 90 struct dma_attrs *attrs) 91 { 92 } 93 94 static int dma_direct_dma_supported(struct device *dev, u64 mask) 95 { 96 return 1; 97 } 98 99 static inline dma_addr_t dma_direct_map_page(struct device *dev, 100 struct page *page, 101 unsigned long offset, 102 size_t size, 103 enum dma_data_direction direction, 104 struct dma_attrs *attrs) 105 { 106 __dma_sync(page_to_phys(page) + offset, size, direction); 107 return page_to_phys(page) + offset + get_dma_direct_offset(dev); 108 } 109 110 static inline void dma_direct_unmap_page(struct device *dev, 111 dma_addr_t dma_address, 112 size_t size, 113 enum dma_data_direction direction, 114 struct dma_attrs *attrs) 115 { 116 /* There is not necessary to do cache cleanup 117 * 118 * phys_to_virt is here because in __dma_sync_page is __virt_to_phys and 119 * dma_address is physical address 120 */ 121 __dma_sync(dma_address, size, direction); 122 } 123 124 static inline void 125 dma_direct_sync_single_for_cpu(struct device *dev, 126 dma_addr_t dma_handle, size_t size, 127 enum dma_data_direction direction) 128 { 129 /* 130 * It's pointless to flush the cache as the memory segment 131 * is given to the CPU 132 */ 133 134 if (direction == DMA_FROM_DEVICE) 135 __dma_sync(dma_handle, size, direction); 136 } 137 138 static inline void 139 dma_direct_sync_single_for_device(struct device *dev, 140 dma_addr_t dma_handle, size_t size, 141 enum dma_data_direction direction) 142 { 143 /* 144 * It's pointless to invalidate the cache if the device isn't 145 * supposed to write to the relevant region 146 */ 147 148 if (direction == DMA_TO_DEVICE) 149 __dma_sync(dma_handle, size, direction); 150 } 151 152 static inline void 153 dma_direct_sync_sg_for_cpu(struct device *dev, 154 struct scatterlist *sgl, int nents, 155 enum dma_data_direction direction) 156 { 157 struct scatterlist *sg; 158 int i; 159 160 /* FIXME this part of code is untested */ 161 if (direction == DMA_FROM_DEVICE) 162 for_each_sg(sgl, sg, nents, i) 163 __dma_sync(sg->dma_address, sg->length, direction); 164 } 165 166 static inline void 167 dma_direct_sync_sg_for_device(struct device *dev, 168 struct scatterlist *sgl, int nents, 169 enum dma_data_direction direction) 170 { 171 struct scatterlist *sg; 172 int i; 173 174 /* FIXME this part of code is untested */ 175 if (direction == DMA_TO_DEVICE) 176 for_each_sg(sgl, sg, nents, i) 177 __dma_sync(sg->dma_address, sg->length, direction); 178 } 179 180 struct dma_map_ops dma_direct_ops = { 181 .alloc = dma_direct_alloc_coherent, 182 .free = dma_direct_free_coherent, 183 .map_sg = dma_direct_map_sg, 184 .unmap_sg = dma_direct_unmap_sg, 185 .dma_supported = dma_direct_dma_supported, 186 .map_page = dma_direct_map_page, 187 .unmap_page = dma_direct_unmap_page, 188 .sync_single_for_cpu = dma_direct_sync_single_for_cpu, 189 .sync_single_for_device = dma_direct_sync_single_for_device, 190 .sync_sg_for_cpu = dma_direct_sync_sg_for_cpu, 191 .sync_sg_for_device = dma_direct_sync_sg_for_device, 192 }; 193 EXPORT_SYMBOL(dma_direct_ops); 194 195 /* Number of entries preallocated for DMA-API debugging */ 196 #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16) 197 198 static int __init dma_init(void) 199 { 200 dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES); 201 202 return 0; 203 } 204 fs_initcall(dma_init); 205