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