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3243 | Serge | 1 | #ifndef _LINUX_SCATTERLIST_H |
2 | #define _LINUX_SCATTERLIST_H |
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3 | |||
4 | #include |
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5 | #include |
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6 | #include |
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7 | |||
8 | #include |
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9 | #include |
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10 | //#include |
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11 | |||
12 | struct sg_table { |
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13 | struct scatterlist *sgl; /* the list */ |
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14 | unsigned int nents; /* number of mapped entries */ |
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15 | unsigned int orig_nents; /* original size of list */ |
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16 | }; |
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17 | |||
18 | /* |
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19 | * Notes on SG table design. |
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20 | * |
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21 | * Architectures must provide an unsigned long page_link field in the |
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22 | * scatterlist struct. We use that to place the page pointer AND encode |
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23 | * information about the sg table as well. The two lower bits are reserved |
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24 | * for this information. |
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25 | * |
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26 | * If bit 0 is set, then the page_link contains a pointer to the next sg |
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27 | * table list. Otherwise the next entry is at sg + 1. |
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28 | * |
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29 | * If bit 1 is set, then this sg entry is the last element in a list. |
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30 | * |
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31 | * See sg_next(). |
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32 | * |
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33 | */ |
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34 | |||
35 | #define SG_MAGIC 0x87654321 |
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36 | |||
37 | /* |
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38 | * We overload the LSB of the page pointer to indicate whether it's |
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39 | * a valid sg entry, or whether it points to the start of a new scatterlist. |
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40 | * Those low bits are there for everyone! (thanks mason :-) |
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41 | */ |
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42 | #define sg_is_chain(sg) ((sg)->page_link & 0x01) |
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43 | #define sg_is_last(sg) ((sg)->page_link & 0x02) |
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44 | #define sg_chain_ptr(sg) \ |
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45 | ((struct scatterlist *) ((sg)->page_link & ~0x03)) |
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46 | |||
47 | /** |
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48 | * sg_assign_page - Assign a given page to an SG entry |
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49 | * @sg: SG entry |
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50 | * @page: The page |
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51 | * |
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52 | * Description: |
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53 | * Assign page to sg entry. Also see sg_set_page(), the most commonly used |
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54 | * variant. |
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55 | * |
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56 | **/ |
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57 | static inline void sg_assign_page(struct scatterlist *sg, struct page *page) |
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58 | { |
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59 | unsigned long page_link = sg->page_link & 0x3; |
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60 | |||
61 | /* |
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62 | * In order for the low bit stealing approach to work, pages |
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63 | * must be aligned at a 32-bit boundary as a minimum. |
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64 | */ |
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65 | BUG_ON((unsigned long) page & 0x03); |
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66 | #ifdef CONFIG_DEBUG_SG |
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67 | BUG_ON(sg->sg_magic != SG_MAGIC); |
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68 | BUG_ON(sg_is_chain(sg)); |
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69 | #endif |
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70 | sg->page_link = page_link | (unsigned long) page; |
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71 | } |
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72 | |||
73 | /** |
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74 | * sg_set_page - Set sg entry to point at given page |
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75 | * @sg: SG entry |
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76 | * @page: The page |
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77 | * @len: Length of data |
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78 | * @offset: Offset into page |
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79 | * |
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80 | * Description: |
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81 | * Use this function to set an sg entry pointing at a page, never assign |
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82 | * the page directly. We encode sg table information in the lower bits |
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83 | * of the page pointer. See sg_page() for looking up the page belonging |
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84 | * to an sg entry. |
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85 | * |
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86 | **/ |
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87 | static inline void sg_set_page(struct scatterlist *sg, struct page *page, |
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88 | unsigned int len, unsigned int offset) |
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89 | { |
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90 | sg_assign_page(sg, page); |
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91 | sg->offset = offset; |
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92 | sg->length = len; |
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93 | } |
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94 | |||
95 | static inline struct page *sg_page(struct scatterlist *sg) |
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96 | { |
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97 | #ifdef CONFIG_DEBUG_SG |
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98 | BUG_ON(sg->sg_magic != SG_MAGIC); |
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99 | BUG_ON(sg_is_chain(sg)); |
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100 | #endif |
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101 | return (struct page *)((sg)->page_link & ~0x3); |
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102 | } |
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103 | |||
104 | /** |
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105 | * sg_set_buf - Set sg entry to point at given data |
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106 | * @sg: SG entry |
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107 | * @buf: Data |
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108 | * @buflen: Data length |
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109 | * |
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110 | **/ |
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111 | //static inline void sg_set_buf(struct scatterlist *sg, const void *buf, |
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112 | // unsigned int buflen) |
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113 | //{ |
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114 | // sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); |
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115 | //} |
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116 | |||
117 | /* |
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118 | * Loop over each sg element, following the pointer to a new list if necessary |
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119 | */ |
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120 | #define for_each_sg(sglist, sg, nr, __i) \ |
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121 | for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg)) |
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122 | |||
123 | /** |
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124 | * sg_chain - Chain two sglists together |
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125 | * @prv: First scatterlist |
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126 | * @prv_nents: Number of entries in prv |
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127 | * @sgl: Second scatterlist |
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128 | * |
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129 | * Description: |
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130 | * Links @prv@ and @sgl@ together, to form a longer scatterlist. |
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131 | * |
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132 | **/ |
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133 | static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, |
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134 | struct scatterlist *sgl) |
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135 | { |
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136 | #ifndef ARCH_HAS_SG_CHAIN |
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137 | BUG(); |
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138 | #endif |
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139 | |||
140 | /* |
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141 | * offset and length are unused for chain entry. Clear them. |
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142 | */ |
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143 | prv[prv_nents - 1].offset = 0; |
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144 | prv[prv_nents - 1].length = 0; |
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145 | |||
146 | /* |
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147 | * Set lowest bit to indicate a link pointer, and make sure to clear |
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148 | * the termination bit if it happens to be set. |
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149 | */ |
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150 | prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02; |
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151 | } |
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152 | |||
153 | /** |
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154 | * sg_mark_end - Mark the end of the scatterlist |
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155 | * @sg: SG entryScatterlist |
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156 | * |
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157 | * Description: |
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158 | * Marks the passed in sg entry as the termination point for the sg |
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159 | * table. A call to sg_next() on this entry will return NULL. |
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160 | * |
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161 | **/ |
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162 | static inline void sg_mark_end(struct scatterlist *sg) |
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163 | { |
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164 | #ifdef CONFIG_DEBUG_SG |
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165 | BUG_ON(sg->sg_magic != SG_MAGIC); |
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166 | #endif |
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167 | /* |
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168 | * Set termination bit, clear potential chain bit |
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169 | */ |
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170 | sg->page_link |= 0x02; |
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171 | sg->page_link &= ~0x01; |
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172 | } |
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173 | |||
174 | /** |
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175 | * sg_phys - Return physical address of an sg entry |
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176 | * @sg: SG entry |
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177 | * |
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178 | * Description: |
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179 | * This calls page_to_phys() on the page in this sg entry, and adds the |
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180 | * sg offset. The caller must know that it is legal to call page_to_phys() |
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181 | * on the sg page. |
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182 | * |
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183 | **/ |
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184 | static inline dma_addr_t sg_phys(struct scatterlist *sg) |
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185 | { |
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186 | return page_to_phys(sg_page(sg)) + sg->offset; |
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187 | } |
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188 | |||
189 | /** |
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190 | * sg_virt - Return virtual address of an sg entry |
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191 | * @sg: SG entry |
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192 | * |
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193 | * Description: |
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194 | * This calls page_address() on the page in this sg entry, and adds the |
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195 | * sg offset. The caller must know that the sg page has a valid virtual |
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196 | * mapping. |
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197 | * |
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198 | **/ |
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199 | //static inline void *sg_virt(struct scatterlist *sg) |
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200 | //{ |
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201 | // return page_address(sg_page(sg)) + sg->offset; |
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202 | //} |
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203 | |||
204 | int sg_nents(struct scatterlist *sg); |
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205 | struct scatterlist *sg_next(struct scatterlist *); |
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206 | struct scatterlist *sg_last(struct scatterlist *s, unsigned int); |
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207 | void sg_init_table(struct scatterlist *, unsigned int); |
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208 | void sg_init_one(struct scatterlist *, const void *, unsigned int); |
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209 | |||
210 | typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t); |
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211 | typedef void (sg_free_fn)(struct scatterlist *, unsigned int); |
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212 | |||
213 | void __sg_free_table(struct sg_table *, unsigned int, sg_free_fn *); |
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214 | void sg_free_table(struct sg_table *); |
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215 | int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, gfp_t, |
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216 | sg_alloc_fn *); |
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217 | int sg_alloc_table(struct sg_table *, unsigned int, gfp_t); |
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218 | int sg_alloc_table_from_pages(struct sg_table *sgt, |
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219 | struct page **pages, unsigned int n_pages, |
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220 | unsigned long offset, unsigned long size, |
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221 | gfp_t gfp_mask); |
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222 | |||
223 | size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, |
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224 | void *buf, size_t buflen); |
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225 | size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, |
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226 | void *buf, size_t buflen); |
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227 | |||
228 | /* |
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229 | * Maximum number of entries that will be allocated in one piece, if |
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230 | * a list larger than this is required then chaining will be utilized. |
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231 | */ |
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232 | #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) |
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233 | |||
234 | |||
235 | /* |
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236 | * Mapping sg iterator |
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237 | * |
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238 | * Iterates over sg entries mapping page-by-page. On each successful |
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239 | * iteration, @miter->page points to the mapped page and |
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240 | * @miter->length bytes of data can be accessed at @miter->addr. As |
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241 | * long as an interation is enclosed between start and stop, the user |
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242 | * is free to choose control structure and when to stop. |
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243 | * |
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244 | * @miter->consumed is set to @miter->length on each iteration. It |
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245 | * can be adjusted if the user can't consume all the bytes in one go. |
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246 | * Also, a stopped iteration can be resumed by calling next on it. |
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247 | * This is useful when iteration needs to release all resources and |
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248 | * continue later (e.g. at the next interrupt). |
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249 | */ |
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250 | |||
251 | #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */ |
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252 | #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */ |
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253 | #define SG_MITER_FROM_SG (1 << 2) /* nop */ |
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254 | |||
255 | struct sg_mapping_iter { |
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256 | /* the following three fields can be accessed directly */ |
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257 | struct page *page; /* currently mapped page */ |
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258 | void *addr; /* pointer to the mapped area */ |
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259 | size_t length; /* length of the mapped area */ |
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260 | size_t consumed; /* number of consumed bytes */ |
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261 | |||
262 | /* these are internal states, keep away */ |
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263 | struct scatterlist *__sg; /* current entry */ |
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264 | unsigned int __nents; /* nr of remaining entries */ |
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265 | unsigned int __offset; /* offset within sg */ |
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266 | unsigned int __flags; |
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267 | }; |
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268 | |||
269 | void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, |
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270 | unsigned int nents, unsigned int flags); |
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271 | bool sg_miter_next(struct sg_mapping_iter *miter); |
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272 | void sg_miter_stop(struct sg_mapping_iter *miter); |
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273 | |||
274 | #endif /* _LINUX_SCATTERLIST_H */><>><>><>> |