1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * xor offload engine api 4 * 5 * Copyright © 2006, Intel Corporation. 6 * 7 * Dan Williams <dan.j.williams@intel.com> 8 * 9 * with architecture considerations by: 10 * Neil Brown <neilb@suse.de> 11 * Jeff Garzik <jeff@garzik.org> 12 */ 13 #include <linux/kernel.h> 14 #include <linux/interrupt.h> 15 #include <linux/module.h> 16 #include <linux/mm.h> 17 #include <linux/dma-mapping.h> 18 #include <linux/raid/xor.h> 19 #include <linux/async_tx.h> 20 21 /* do_async_xor - dma map the pages and perform the xor with an engine */ 22 static __async_inline struct dma_async_tx_descriptor * 23 do_async_xor(struct dma_chan *chan, struct dmaengine_unmap_data *unmap, 24 struct async_submit_ctl *submit) 25 { 26 struct dma_device *dma = chan->device; 27 struct dma_async_tx_descriptor *tx = NULL; 28 dma_async_tx_callback cb_fn_orig = submit->cb_fn; 29 void *cb_param_orig = submit->cb_param; 30 enum async_tx_flags flags_orig = submit->flags; 31 enum dma_ctrl_flags dma_flags = 0; 32 int src_cnt = unmap->to_cnt; 33 int xor_src_cnt; 34 dma_addr_t dma_dest = unmap->addr[unmap->to_cnt]; 35 dma_addr_t *src_list = unmap->addr; 36 37 while (src_cnt) { 38 dma_addr_t tmp; 39 40 submit->flags = flags_orig; 41 xor_src_cnt = min(src_cnt, (int)dma->max_xor); 42 /* if we are submitting additional xors, leave the chain open 43 * and clear the callback parameters 44 */ 45 if (src_cnt > xor_src_cnt) { 46 submit->flags &= ~ASYNC_TX_ACK; 47 submit->flags |= ASYNC_TX_FENCE; 48 submit->cb_fn = NULL; 49 submit->cb_param = NULL; 50 } else { 51 submit->cb_fn = cb_fn_orig; 52 submit->cb_param = cb_param_orig; 53 } 54 if (submit->cb_fn) 55 dma_flags |= DMA_PREP_INTERRUPT; 56 if (submit->flags & ASYNC_TX_FENCE) 57 dma_flags |= DMA_PREP_FENCE; 58 59 /* Drivers force forward progress in case they can not provide a 60 * descriptor 61 */ 62 tmp = src_list[0]; 63 if (src_list > unmap->addr) 64 src_list[0] = dma_dest; 65 tx = dma->device_prep_dma_xor(chan, dma_dest, src_list, 66 xor_src_cnt, unmap->len, 67 dma_flags); 68 69 if (unlikely(!tx)) 70 async_tx_quiesce(&submit->depend_tx); 71 72 /* spin wait for the preceding transactions to complete */ 73 while (unlikely(!tx)) { 74 dma_async_issue_pending(chan); 75 tx = dma->device_prep_dma_xor(chan, dma_dest, 76 src_list, 77 xor_src_cnt, unmap->len, 78 dma_flags); 79 } 80 src_list[0] = tmp; 81 82 dma_set_unmap(tx, unmap); 83 async_tx_submit(chan, tx, submit); 84 submit->depend_tx = tx; 85 86 if (src_cnt > xor_src_cnt) { 87 /* drop completed sources */ 88 src_cnt -= xor_src_cnt; 89 /* use the intermediate result a source */ 90 src_cnt++; 91 src_list += xor_src_cnt - 1; 92 } else 93 break; 94 } 95 96 return tx; 97 } 98 99 static void 100 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset, 101 int src_cnt, size_t len, struct async_submit_ctl *submit) 102 { 103 int i; 104 int xor_src_cnt = 0; 105 int src_off = 0; 106 void *dest_buf; 107 void **srcs; 108 109 if (submit->scribble) 110 srcs = submit->scribble; 111 else 112 srcs = (void **) src_list; 113 114 /* convert to buffer pointers */ 115 for (i = 0; i < src_cnt; i++) 116 if (src_list[i]) 117 srcs[xor_src_cnt++] = page_address(src_list[i]) + offset; 118 src_cnt = xor_src_cnt; 119 /* set destination address */ 120 dest_buf = page_address(dest) + offset; 121 122 if (submit->flags & ASYNC_TX_XOR_ZERO_DST) 123 memset(dest_buf, 0, len); 124 125 while (src_cnt > 0) { 126 /* process up to 'MAX_XOR_BLOCKS' sources */ 127 xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS); 128 xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]); 129 130 /* drop completed sources */ 131 src_cnt -= xor_src_cnt; 132 src_off += xor_src_cnt; 133 } 134 135 async_tx_sync_epilog(submit); 136 } 137 138 /** 139 * async_xor - attempt to xor a set of blocks with a dma engine. 140 * @dest: destination page 141 * @src_list: array of source pages 142 * @offset: common src/dst offset to start transaction 143 * @src_cnt: number of source pages 144 * @len: length in bytes 145 * @submit: submission / completion modifiers 146 * 147 * honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST 148 * 149 * xor_blocks always uses the dest as a source so the 150 * ASYNC_TX_XOR_ZERO_DST flag must be set to not include dest data in 151 * the calculation. The assumption with dma eninges is that they only 152 * use the destination buffer as a source when it is explicity specified 153 * in the source list. 154 * 155 * src_list note: if the dest is also a source it must be at index zero. 156 * The contents of this array will be overwritten if a scribble region 157 * is not specified. 158 */ 159 struct dma_async_tx_descriptor * 160 async_xor(struct page *dest, struct page **src_list, unsigned int offset, 161 int src_cnt, size_t len, struct async_submit_ctl *submit) 162 { 163 struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR, 164 &dest, 1, src_list, 165 src_cnt, len); 166 struct dma_device *device = chan ? chan->device : NULL; 167 struct dmaengine_unmap_data *unmap = NULL; 168 169 BUG_ON(src_cnt <= 1); 170 171 if (device) 172 unmap = dmaengine_get_unmap_data(device->dev, src_cnt+1, GFP_NOWAIT); 173 174 if (unmap && is_dma_xor_aligned(device, offset, 0, len)) { 175 struct dma_async_tx_descriptor *tx; 176 int i, j; 177 178 /* run the xor asynchronously */ 179 pr_debug("%s (async): len: %zu\n", __func__, len); 180 181 unmap->len = len; 182 for (i = 0, j = 0; i < src_cnt; i++) { 183 if (!src_list[i]) 184 continue; 185 unmap->to_cnt++; 186 unmap->addr[j++] = dma_map_page(device->dev, src_list[i], 187 offset, len, DMA_TO_DEVICE); 188 } 189 190 /* map it bidirectional as it may be re-used as a source */ 191 unmap->addr[j] = dma_map_page(device->dev, dest, offset, len, 192 DMA_BIDIRECTIONAL); 193 unmap->bidi_cnt = 1; 194 195 tx = do_async_xor(chan, unmap, submit); 196 dmaengine_unmap_put(unmap); 197 return tx; 198 } else { 199 dmaengine_unmap_put(unmap); 200 /* run the xor synchronously */ 201 pr_debug("%s (sync): len: %zu\n", __func__, len); 202 WARN_ONCE(chan, "%s: no space for dma address conversion\n", 203 __func__); 204 205 /* in the sync case the dest is an implied source 206 * (assumes the dest is the first source) 207 */ 208 if (submit->flags & ASYNC_TX_XOR_DROP_DST) { 209 src_cnt--; 210 src_list++; 211 } 212 213 /* wait for any prerequisite operations */ 214 async_tx_quiesce(&submit->depend_tx); 215 216 do_sync_xor(dest, src_list, offset, src_cnt, len, submit); 217 218 return NULL; 219 } 220 } 221 EXPORT_SYMBOL_GPL(async_xor); 222 223 static int page_is_zero(struct page *p, unsigned int offset, size_t len) 224 { 225 return !memchr_inv(page_address(p) + offset, 0, len); 226 } 227 228 static inline struct dma_chan * 229 xor_val_chan(struct async_submit_ctl *submit, struct page *dest, 230 struct page **src_list, int src_cnt, size_t len) 231 { 232 #ifdef CONFIG_ASYNC_TX_DISABLE_XOR_VAL_DMA 233 return NULL; 234 #endif 235 return async_tx_find_channel(submit, DMA_XOR_VAL, &dest, 1, src_list, 236 src_cnt, len); 237 } 238 239 /** 240 * async_xor_val - attempt a xor parity check with a dma engine. 241 * @dest: destination page used if the xor is performed synchronously 242 * @src_list: array of source pages 243 * @offset: offset in pages to start transaction 244 * @src_cnt: number of source pages 245 * @len: length in bytes 246 * @result: 0 if sum == 0 else non-zero 247 * @submit: submission / completion modifiers 248 * 249 * honored flags: ASYNC_TX_ACK 250 * 251 * src_list note: if the dest is also a source it must be at index zero. 252 * The contents of this array will be overwritten if a scribble region 253 * is not specified. 254 */ 255 struct dma_async_tx_descriptor * 256 async_xor_val(struct page *dest, struct page **src_list, unsigned int offset, 257 int src_cnt, size_t len, enum sum_check_flags *result, 258 struct async_submit_ctl *submit) 259 { 260 struct dma_chan *chan = xor_val_chan(submit, dest, src_list, src_cnt, len); 261 struct dma_device *device = chan ? chan->device : NULL; 262 struct dma_async_tx_descriptor *tx = NULL; 263 struct dmaengine_unmap_data *unmap = NULL; 264 265 BUG_ON(src_cnt <= 1); 266 267 if (device) 268 unmap = dmaengine_get_unmap_data(device->dev, src_cnt, GFP_NOWAIT); 269 270 if (unmap && src_cnt <= device->max_xor && 271 is_dma_xor_aligned(device, offset, 0, len)) { 272 unsigned long dma_prep_flags = 0; 273 int i; 274 275 pr_debug("%s: (async) len: %zu\n", __func__, len); 276 277 if (submit->cb_fn) 278 dma_prep_flags |= DMA_PREP_INTERRUPT; 279 if (submit->flags & ASYNC_TX_FENCE) 280 dma_prep_flags |= DMA_PREP_FENCE; 281 282 for (i = 0; i < src_cnt; i++) { 283 unmap->addr[i] = dma_map_page(device->dev, src_list[i], 284 offset, len, DMA_TO_DEVICE); 285 unmap->to_cnt++; 286 } 287 unmap->len = len; 288 289 tx = device->device_prep_dma_xor_val(chan, unmap->addr, src_cnt, 290 len, result, 291 dma_prep_flags); 292 if (unlikely(!tx)) { 293 async_tx_quiesce(&submit->depend_tx); 294 295 while (!tx) { 296 dma_async_issue_pending(chan); 297 tx = device->device_prep_dma_xor_val(chan, 298 unmap->addr, src_cnt, len, result, 299 dma_prep_flags); 300 } 301 } 302 dma_set_unmap(tx, unmap); 303 async_tx_submit(chan, tx, submit); 304 } else { 305 enum async_tx_flags flags_orig = submit->flags; 306 307 pr_debug("%s: (sync) len: %zu\n", __func__, len); 308 WARN_ONCE(device && src_cnt <= device->max_xor, 309 "%s: no space for dma address conversion\n", 310 __func__); 311 312 submit->flags |= ASYNC_TX_XOR_DROP_DST; 313 submit->flags &= ~ASYNC_TX_ACK; 314 315 tx = async_xor(dest, src_list, offset, src_cnt, len, submit); 316 317 async_tx_quiesce(&tx); 318 319 *result = !page_is_zero(dest, offset, len) << SUM_CHECK_P; 320 321 async_tx_sync_epilog(submit); 322 submit->flags = flags_orig; 323 } 324 dmaengine_unmap_put(unmap); 325 326 return tx; 327 } 328 EXPORT_SYMBOL_GPL(async_xor_val); 329 330 MODULE_AUTHOR("Intel Corporation"); 331 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api"); 332 MODULE_LICENSE("GPL"); 333