2 * xor offload engine api
4 * Copyright © 2006, Intel Corporation.
6 * Dan Williams <dan.j.williams@intel.com>
8 * with architecture considerations by:
9 * Neil Brown <neilb@suse.de>
10 * Jeff Garzik <jeff@garzik.org>
12 * This program is free software; you can redistribute it and/or modify it
13 * under the terms and conditions of the GNU General Public License,
14 * version 2, as published by the Free Software Foundation.
16 * This program is distributed in the hope it will be useful, but WITHOUT
17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
18 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
21 * You should have received a copy of the GNU General Public License along with
22 * this program; if not, write to the Free Software Foundation, Inc.,
23 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
26 #include <linux/kernel.h>
27 #include <linux/interrupt.h>
29 #include <linux/dma-mapping.h>
30 #include <linux/raid/xor.h>
31 #include <linux/async_tx.h>
33 /* do_async_xor - dma map the pages and perform the xor with an engine */
34 static __async_inline struct dma_async_tx_descriptor *
35 do_async_xor(struct dma_chan *chan, struct page *dest, struct page **src_list,
36 unsigned int offset, int src_cnt, size_t len,
37 struct async_submit_ctl *submit)
39 struct dma_device *dma = chan->device;
40 dma_addr_t *dma_src = (dma_addr_t *) src_list;
41 struct dma_async_tx_descriptor *tx = NULL;
44 dma_async_tx_callback cb_fn_orig = submit->cb_fn;
45 void *cb_param_orig = submit->cb_param;
46 enum async_tx_flags flags_orig = submit->flags;
47 enum dma_ctrl_flags dma_flags;
51 /* map the dest bidrectional in case it is re-used as a source */
52 dma_dest = dma_map_page(dma->dev, dest, offset, len, DMA_BIDIRECTIONAL);
53 for (i = 0; i < src_cnt; i++) {
54 /* only map the dest once */
55 if (unlikely(src_list[i] == dest)) {
56 dma_src[i] = dma_dest;
59 dma_src[i] = dma_map_page(dma->dev, src_list[i], offset,
64 submit->flags = flags_orig;
66 xor_src_cnt = min(src_cnt, dma->max_xor);
67 /* if we are submitting additional xors, leave the chain open,
68 * clear the callback parameters, and leave the destination
71 if (src_cnt > xor_src_cnt) {
72 submit->flags &= ~ASYNC_TX_ACK;
73 dma_flags = DMA_COMPL_SKIP_DEST_UNMAP;
75 submit->cb_param = NULL;
77 submit->cb_fn = cb_fn_orig;
78 submit->cb_param = cb_param_orig;
81 dma_flags |= DMA_PREP_INTERRUPT;
83 /* Since we have clobbered the src_list we are committed
84 * to doing this asynchronously. Drivers force forward progress
85 * in case they can not provide a descriptor
87 tx = dma->device_prep_dma_xor(chan, dma_dest, &dma_src[src_off],
88 xor_src_cnt, len, dma_flags);
91 async_tx_quiesce(&submit->depend_tx);
93 /* spin wait for the preceeding transactions to complete */
94 while (unlikely(!tx)) {
95 dma_async_issue_pending(chan);
96 tx = dma->device_prep_dma_xor(chan, dma_dest,
102 async_tx_submit(chan, tx, submit);
103 submit->depend_tx = tx;
105 if (src_cnt > xor_src_cnt) {
106 /* drop completed sources */
107 src_cnt -= xor_src_cnt;
108 src_off += xor_src_cnt;
110 /* use the intermediate result a source */
111 dma_src[--src_off] = dma_dest;
121 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
122 int src_cnt, size_t len, struct async_submit_ctl *submit)
128 void **srcs = (void **) src_list;
130 /* reuse the 'src_list' array to convert to buffer pointers */
131 for (i = 0; i < src_cnt; i++)
132 srcs[i] = page_address(src_list[i]) + offset;
134 /* set destination address */
135 dest_buf = page_address(dest) + offset;
137 if (submit->flags & ASYNC_TX_XOR_ZERO_DST)
138 memset(dest_buf, 0, len);
140 while (src_cnt > 0) {
141 /* process up to 'MAX_XOR_BLOCKS' sources */
142 xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
143 xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]);
145 /* drop completed sources */
146 src_cnt -= xor_src_cnt;
147 src_off += xor_src_cnt;
150 async_tx_sync_epilog(submit);
154 * async_xor - attempt to xor a set of blocks with a dma engine.
155 * @dest: destination page
156 * @src_list: array of source pages
157 * @offset: common src/dst offset to start transaction
158 * @src_cnt: number of source pages
159 * @len: length in bytes
160 * @submit: submission / completion modifiers
162 * honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST
164 * xor_blocks always uses the dest as a source so the
165 * ASYNC_TX_XOR_ZERO_DST flag must be set to not include dest data in
166 * the calculation. The assumption with dma eninges is that they only
167 * use the destination buffer as a source when it is explicity specified
168 * in the source list.
170 * src_list note: if the dest is also a source it must be at index zero.
171 * The contents of this array will be overwritten if a scribble region
174 struct dma_async_tx_descriptor *
175 async_xor(struct page *dest, struct page **src_list, unsigned int offset,
176 int src_cnt, size_t len, struct async_submit_ctl *submit)
178 struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR,
181 BUG_ON(src_cnt <= 1);
184 /* run the xor asynchronously */
185 pr_debug("%s (async): len: %zu\n", __func__, len);
187 return do_async_xor(chan, dest, src_list, offset, src_cnt, len,
190 /* run the xor synchronously */
191 pr_debug("%s (sync): len: %zu\n", __func__, len);
193 /* in the sync case the dest is an implied source
194 * (assumes the dest is the first source)
196 if (submit->flags & ASYNC_TX_XOR_DROP_DST) {
201 /* wait for any prerequisite operations */
202 async_tx_quiesce(&submit->depend_tx);
204 do_sync_xor(dest, src_list, offset, src_cnt, len, submit);
209 EXPORT_SYMBOL_GPL(async_xor);
211 static int page_is_zero(struct page *p, unsigned int offset, size_t len)
213 char *a = page_address(p) + offset;
214 return ((*(u32 *) a) == 0 &&
215 memcmp(a, a + 4, len - 4) == 0);
219 * async_xor_val - attempt a xor parity check with a dma engine.
220 * @dest: destination page used if the xor is performed synchronously
221 * @src_list: array of source pages
222 * @offset: offset in pages to start transaction
223 * @src_cnt: number of source pages
224 * @len: length in bytes
225 * @result: 0 if sum == 0 else non-zero
226 * @submit: submission / completion modifiers
228 * honored flags: ASYNC_TX_ACK
230 * src_list note: if the dest is also a source it must be at index zero.
231 * The contents of this array will be overwritten if a scribble region
234 struct dma_async_tx_descriptor *
235 async_xor_val(struct page *dest, struct page **src_list, unsigned int offset,
236 int src_cnt, size_t len, u32 *result,
237 struct async_submit_ctl *submit)
239 struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR_VAL,
242 struct dma_device *device = chan ? chan->device : NULL;
243 struct dma_async_tx_descriptor *tx = NULL;
245 BUG_ON(src_cnt <= 1);
247 if (device && src_cnt <= device->max_xor) {
248 dma_addr_t *dma_src = (dma_addr_t *) src_list;
249 unsigned long dma_prep_flags;
252 pr_debug("%s: (async) len: %zu\n", __func__, len);
254 dma_prep_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
255 for (i = 0; i < src_cnt; i++)
256 dma_src[i] = dma_map_page(device->dev, src_list[i],
257 offset, len, DMA_TO_DEVICE);
259 tx = device->device_prep_dma_xor_val(chan, dma_src, src_cnt,
263 async_tx_quiesce(&submit->depend_tx);
266 dma_async_issue_pending(chan);
267 tx = device->device_prep_dma_xor_val(chan,
268 dma_src, src_cnt, len, result,
273 async_tx_submit(chan, tx, submit);
275 enum async_tx_flags flags_orig = submit->flags;
277 pr_debug("%s: (sync) len: %zu\n", __func__, len);
279 submit->flags |= ASYNC_TX_XOR_DROP_DST;
280 submit->flags &= ~ASYNC_TX_ACK;
282 tx = async_xor(dest, src_list, offset, src_cnt, len, submit);
284 async_tx_quiesce(&tx);
286 *result = page_is_zero(dest, offset, len) ? 0 : 1;
288 async_tx_sync_epilog(submit);
289 submit->flags = flags_orig;
294 EXPORT_SYMBOL_GPL(async_xor_val);
296 static int __init async_xor_init(void)
298 #ifdef CONFIG_DMA_ENGINE
299 /* To conserve stack space the input src_list (array of page pointers)
300 * is reused to hold the array of dma addresses passed to the driver.
301 * This conversion is only possible when dma_addr_t is less than the
302 * the size of a pointer. HIGHMEM64G is known to violate this
305 BUILD_BUG_ON(sizeof(dma_addr_t) > sizeof(struct page *));
311 static void __exit async_xor_exit(void)
316 module_init(async_xor_init);
317 module_exit(async_xor_exit);
319 MODULE_AUTHOR("Intel Corporation");
320 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
321 MODULE_LICENSE("GPL");