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>
28 #include <linux/module.h>
30 #include <linux/dma-mapping.h>
31 #include <linux/raid/xor.h>
32 #include <linux/async_tx.h>
34 /* do_async_xor - dma map the pages and perform the xor with an engine */
35 static __async_inline struct dma_async_tx_descriptor *
36 do_async_xor(struct dma_chan *chan, struct dmaengine_unmap_data *unmap,
37 struct async_submit_ctl *submit)
39 struct dma_device *dma = chan->device;
40 struct dma_async_tx_descriptor *tx = NULL;
41 dma_async_tx_callback cb_fn_orig = submit->cb_fn;
42 void *cb_param_orig = submit->cb_param;
43 enum async_tx_flags flags_orig = submit->flags;
44 enum dma_ctrl_flags dma_flags = 0;
45 int src_cnt = unmap->to_cnt;
47 dma_addr_t dma_dest = unmap->addr[unmap->to_cnt];
48 dma_addr_t *src_list = unmap->addr;
53 submit->flags = flags_orig;
54 xor_src_cnt = min(src_cnt, (int)dma->max_xor);
55 /* if we are submitting additional xors, leave the chain open
56 * and clear the callback parameters
58 if (src_cnt > xor_src_cnt) {
59 submit->flags &= ~ASYNC_TX_ACK;
60 submit->flags |= ASYNC_TX_FENCE;
62 submit->cb_param = NULL;
64 submit->cb_fn = cb_fn_orig;
65 submit->cb_param = cb_param_orig;
68 dma_flags |= DMA_PREP_INTERRUPT;
69 if (submit->flags & ASYNC_TX_FENCE)
70 dma_flags |= DMA_PREP_FENCE;
72 /* Drivers force forward progress in case they can not provide a
76 if (src_list > unmap->addr)
77 src_list[0] = dma_dest;
78 tx = dma->device_prep_dma_xor(chan, dma_dest, src_list,
79 xor_src_cnt, unmap->len,
85 async_tx_quiesce(&submit->depend_tx);
87 /* spin wait for the preceding transactions to complete */
88 while (unlikely(!tx)) {
89 dma_async_issue_pending(chan);
90 tx = dma->device_prep_dma_xor(chan, dma_dest,
92 xor_src_cnt, unmap->len,
96 dma_set_unmap(tx, unmap);
97 async_tx_submit(chan, tx, submit);
98 submit->depend_tx = tx;
100 if (src_cnt > xor_src_cnt) {
101 /* drop completed sources */
102 src_cnt -= xor_src_cnt;
103 /* use the intermediate result a source */
105 src_list += xor_src_cnt - 1;
114 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
115 int src_cnt, size_t len, struct async_submit_ctl *submit)
123 if (submit->scribble)
124 srcs = submit->scribble;
126 srcs = (void **) src_list;
128 /* convert to buffer pointers */
129 for (i = 0; i < src_cnt; i++)
131 srcs[xor_src_cnt++] = page_address(src_list[i]) + offset;
132 src_cnt = xor_src_cnt;
133 /* set destination address */
134 dest_buf = page_address(dest) + offset;
136 if (submit->flags & ASYNC_TX_XOR_ZERO_DST)
137 memset(dest_buf, 0, len);
139 while (src_cnt > 0) {
140 /* process up to 'MAX_XOR_BLOCKS' sources */
141 xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
142 xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]);
144 /* drop completed sources */
145 src_cnt -= xor_src_cnt;
146 src_off += xor_src_cnt;
149 async_tx_sync_epilog(submit);
153 * async_xor - attempt to xor a set of blocks with a dma engine.
154 * @dest: destination page
155 * @src_list: array of source pages
156 * @offset: common src/dst offset to start transaction
157 * @src_cnt: number of source pages
158 * @len: length in bytes
159 * @submit: submission / completion modifiers
161 * honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST
163 * xor_blocks always uses the dest as a source so the
164 * ASYNC_TX_XOR_ZERO_DST flag must be set to not include dest data in
165 * the calculation. The assumption with dma eninges is that they only
166 * use the destination buffer as a source when it is explicity specified
167 * in the source list.
169 * src_list note: if the dest is also a source it must be at index zero.
170 * The contents of this array will be overwritten if a scribble region
173 struct dma_async_tx_descriptor *
174 async_xor(struct page *dest, struct page **src_list, unsigned int offset,
175 int src_cnt, size_t len, struct async_submit_ctl *submit)
177 struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR,
180 struct dma_device *device = chan ? chan->device : NULL;
181 struct dmaengine_unmap_data *unmap = NULL;
183 BUG_ON(src_cnt <= 1);
186 unmap = dmaengine_get_unmap_data(device->dev, src_cnt+1, GFP_NOIO);
188 if (unmap && is_dma_xor_aligned(device, offset, 0, len)) {
189 struct dma_async_tx_descriptor *tx;
192 /* run the xor asynchronously */
193 pr_debug("%s (async): len: %zu\n", __func__, len);
196 for (i = 0, j = 0; i < src_cnt; i++) {
200 unmap->addr[j++] = dma_map_page(device->dev, src_list[i],
201 offset, len, DMA_TO_DEVICE);
204 /* map it bidirectional as it may be re-used as a source */
205 unmap->addr[j] = dma_map_page(device->dev, dest, offset, len,
209 tx = do_async_xor(chan, unmap, submit);
210 dmaengine_unmap_put(unmap);
213 dmaengine_unmap_put(unmap);
214 /* run the xor synchronously */
215 pr_debug("%s (sync): len: %zu\n", __func__, len);
216 WARN_ONCE(chan, "%s: no space for dma address conversion\n",
219 /* in the sync case the dest is an implied source
220 * (assumes the dest is the first source)
222 if (submit->flags & ASYNC_TX_XOR_DROP_DST) {
227 /* wait for any prerequisite operations */
228 async_tx_quiesce(&submit->depend_tx);
230 do_sync_xor(dest, src_list, offset, src_cnt, len, submit);
235 EXPORT_SYMBOL_GPL(async_xor);
237 static int page_is_zero(struct page *p, unsigned int offset, size_t len)
239 return !memchr_inv(page_address(p) + offset, 0, len);
242 static inline struct dma_chan *
243 xor_val_chan(struct async_submit_ctl *submit, struct page *dest,
244 struct page **src_list, int src_cnt, size_t len)
246 #ifdef CONFIG_ASYNC_TX_DISABLE_XOR_VAL_DMA
249 return async_tx_find_channel(submit, DMA_XOR_VAL, &dest, 1, src_list,
254 * async_xor_val - attempt a xor parity check with a dma engine.
255 * @dest: destination page used if the xor is performed synchronously
256 * @src_list: array of source pages
257 * @offset: offset in pages to start transaction
258 * @src_cnt: number of source pages
259 * @len: length in bytes
260 * @result: 0 if sum == 0 else non-zero
261 * @submit: submission / completion modifiers
263 * honored flags: ASYNC_TX_ACK
265 * src_list note: if the dest is also a source it must be at index zero.
266 * The contents of this array will be overwritten if a scribble region
269 struct dma_async_tx_descriptor *
270 async_xor_val(struct page *dest, struct page **src_list, unsigned int offset,
271 int src_cnt, size_t len, enum sum_check_flags *result,
272 struct async_submit_ctl *submit)
274 struct dma_chan *chan = xor_val_chan(submit, dest, src_list, src_cnt, len);
275 struct dma_device *device = chan ? chan->device : NULL;
276 struct dma_async_tx_descriptor *tx = NULL;
277 struct dmaengine_unmap_data *unmap = NULL;
279 BUG_ON(src_cnt <= 1);
282 unmap = dmaengine_get_unmap_data(device->dev, src_cnt, GFP_NOIO);
284 if (unmap && src_cnt <= device->max_xor &&
285 is_dma_xor_aligned(device, offset, 0, len)) {
286 unsigned long dma_prep_flags = 0;
289 pr_debug("%s: (async) len: %zu\n", __func__, len);
292 dma_prep_flags |= DMA_PREP_INTERRUPT;
293 if (submit->flags & ASYNC_TX_FENCE)
294 dma_prep_flags |= DMA_PREP_FENCE;
296 for (i = 0; i < src_cnt; i++) {
297 unmap->addr[i] = dma_map_page(device->dev, src_list[i],
298 offset, len, DMA_TO_DEVICE);
303 tx = device->device_prep_dma_xor_val(chan, unmap->addr, src_cnt,
307 async_tx_quiesce(&submit->depend_tx);
310 dma_async_issue_pending(chan);
311 tx = device->device_prep_dma_xor_val(chan,
312 unmap->addr, src_cnt, len, result,
316 dma_set_unmap(tx, unmap);
317 async_tx_submit(chan, tx, submit);
319 enum async_tx_flags flags_orig = submit->flags;
321 pr_debug("%s: (sync) len: %zu\n", __func__, len);
322 WARN_ONCE(device && src_cnt <= device->max_xor,
323 "%s: no space for dma address conversion\n",
326 submit->flags |= ASYNC_TX_XOR_DROP_DST;
327 submit->flags &= ~ASYNC_TX_ACK;
329 tx = async_xor(dest, src_list, offset, src_cnt, len, submit);
331 async_tx_quiesce(&tx);
333 *result = !page_is_zero(dest, offset, len) << SUM_CHECK_P;
335 async_tx_sync_epilog(submit);
336 submit->flags = flags_orig;
338 dmaengine_unmap_put(unmap);
342 EXPORT_SYMBOL_GPL(async_xor_val);
344 MODULE_AUTHOR("Intel Corporation");
345 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
346 MODULE_LICENSE("GPL");