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
get_dma_direct_offset(struct device * dev)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
dma_direct_alloc_coherent(struct device * dev,size_t size,dma_addr_t * dma_handle,gfp_t flag)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
dma_direct_free_coherent(struct device * dev,size_t size,void * vaddr,dma_addr_t dma_handle)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
dma_direct_map_sg(struct device * dev,struct scatterlist * sgl,int nents,enum dma_data_direction direction,struct dma_attrs * attrs)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
dma_direct_unmap_sg(struct device * dev,struct scatterlist * sg,int nents,enum dma_data_direction direction,struct dma_attrs * attrs)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
dma_direct_dma_supported(struct device * dev,u64 mask)92 static int dma_direct_dma_supported(struct device *dev, u64 mask)
93 {
94 return 1;
95 }
96
dma_direct_map_page(struct device * dev,struct page * page,unsigned long offset,size_t size,enum dma_data_direction direction,struct dma_attrs * attrs)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
dma_direct_unmap_page(struct device * dev,dma_addr_t dma_address,size_t size,enum dma_data_direction direction,struct dma_attrs * attrs)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
dma_direct_sync_single_for_cpu(struct device * dev,dma_addr_t dma_handle,size_t size,enum dma_data_direction direction)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
dma_direct_sync_single_for_device(struct device * dev,dma_addr_t dma_handle,size_t size,enum dma_data_direction direction)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
dma_direct_sync_sg_for_cpu(struct device * dev,struct scatterlist * sgl,int nents,enum dma_data_direction direction)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
dma_direct_sync_sg_for_device(struct device * dev,struct scatterlist * sgl,int nents,enum dma_data_direction direction)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
dma_init(void)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