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1/*
2 * Copyright(c) 2007 Yuri Tikhonov <yur@emcraft.com>
3 * Copyright(c) 2009 Intel Corporation
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License as published by the Free
7 * Software Foundation; either version 2 of the License, or (at your option)
8 * any later version.
9 *
10 * This program is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
13 * more details.
14 *
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc., 59
17 * Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 *
19 * The full GNU General Public License is included in this distribution in the
20 * file called COPYING.
21 */
22#include <linux/kernel.h>
23#include <linux/interrupt.h>
24#include <linux/module.h>
25#include <linux/dma-mapping.h>
26#include <linux/raid/pq.h>
27#include <linux/async_tx.h>
28#include <linux/gfp.h>
29
30/**
31 * pq_scribble_page - space to hold throwaway P or Q buffer for
32 * synchronous gen_syndrome
33 */
34static struct page *pq_scribble_page;
35
36/* the struct page *blocks[] parameter passed to async_gen_syndrome()
37 * and async_syndrome_val() contains the 'P' destination address at
38 * blocks[disks-2] and the 'Q' destination address at blocks[disks-1]
39 *
40 * note: these are macros as they are used as lvalues
41 */
42#define P(b, d) (b[d-2])
43#define Q(b, d) (b[d-1])
44
45/**
46 * do_async_gen_syndrome - asynchronously calculate P and/or Q
47 */
48static __async_inline struct dma_async_tx_descriptor *
49do_async_gen_syndrome(struct dma_chan *chan, struct page **blocks,
50 const unsigned char *scfs, unsigned int offset, int disks,
51 size_t len, dma_addr_t *dma_src,
52 struct async_submit_ctl *submit)
53{
54 struct dma_async_tx_descriptor *tx = NULL;
55 struct dma_device *dma = chan->device;
56 enum dma_ctrl_flags dma_flags = 0;
57 enum async_tx_flags flags_orig = submit->flags;
58 dma_async_tx_callback cb_fn_orig = submit->cb_fn;
59 dma_async_tx_callback cb_param_orig = submit->cb_param;
60 int src_cnt = disks - 2;
61 unsigned char coefs[src_cnt];
62 unsigned short pq_src_cnt;
63 dma_addr_t dma_dest[2];
64 int src_off = 0;
65 int idx;
66 int i;
67
68 /* DMAs use destinations as sources, so use BIDIRECTIONAL mapping */
69 if (P(blocks, disks))
70 dma_dest[0] = dma_map_page(dma->dev, P(blocks, disks), offset,
71 len, DMA_BIDIRECTIONAL);
72 else
73 dma_flags |= DMA_PREP_PQ_DISABLE_P;
74 if (Q(blocks, disks))
75 dma_dest[1] = dma_map_page(dma->dev, Q(blocks, disks), offset,
76 len, DMA_BIDIRECTIONAL);
77 else
78 dma_flags |= DMA_PREP_PQ_DISABLE_Q;
79
80 /* convert source addresses being careful to collapse 'empty'
81 * sources and update the coefficients accordingly
82 */
83 for (i = 0, idx = 0; i < src_cnt; i++) {
84 if (blocks[i] == NULL)
85 continue;
86 dma_src[idx] = dma_map_page(dma->dev, blocks[i], offset, len,
87 DMA_TO_DEVICE);
88 coefs[idx] = scfs[i];
89 idx++;
90 }
91 src_cnt = idx;
92
93 while (src_cnt > 0) {
94 submit->flags = flags_orig;
95 pq_src_cnt = min(src_cnt, dma_maxpq(dma, dma_flags));
96 /* if we are submitting additional pqs, leave the chain open,
97 * clear the callback parameters, and leave the destination
98 * buffers mapped
99 */
100 if (src_cnt > pq_src_cnt) {
101 submit->flags &= ~ASYNC_TX_ACK;
102 submit->flags |= ASYNC_TX_FENCE;
103 dma_flags |= DMA_COMPL_SKIP_DEST_UNMAP;
104 submit->cb_fn = NULL;
105 submit->cb_param = NULL;
106 } else {
107 dma_flags &= ~DMA_COMPL_SKIP_DEST_UNMAP;
108 submit->cb_fn = cb_fn_orig;
109 submit->cb_param = cb_param_orig;
110 if (cb_fn_orig)
111 dma_flags |= DMA_PREP_INTERRUPT;
112 }
113 if (submit->flags & ASYNC_TX_FENCE)
114 dma_flags |= DMA_PREP_FENCE;
115
116 /* Since we have clobbered the src_list we are committed
117 * to doing this asynchronously. Drivers force forward
118 * progress in case they can not provide a descriptor
119 */
120 for (;;) {
121 tx = dma->device_prep_dma_pq(chan, dma_dest,
122 &dma_src[src_off],
123 pq_src_cnt,
124 &coefs[src_off], len,
125 dma_flags);
126 if (likely(tx))
127 break;
128 async_tx_quiesce(&submit->depend_tx);
129 dma_async_issue_pending(chan);
130 }
131
132 async_tx_submit(chan, tx, submit);
133 submit->depend_tx = tx;
134
135 /* drop completed sources */
136 src_cnt -= pq_src_cnt;
137 src_off += pq_src_cnt;
138
139 dma_flags |= DMA_PREP_CONTINUE;
140 }
141
142 return tx;
143}
144
145/**
146 * do_sync_gen_syndrome - synchronously calculate a raid6 syndrome
147 */
148static void
149do_sync_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
150 size_t len, struct async_submit_ctl *submit)
151{
152 void **srcs;
153 int i;
154
155 if (submit->scribble)
156 srcs = submit->scribble;
157 else
158 srcs = (void **) blocks;
159
160 for (i = 0; i < disks; i++) {
161 if (blocks[i] == NULL) {
162 BUG_ON(i > disks - 3); /* P or Q can't be zero */
163 srcs[i] = (void*)raid6_empty_zero_page;
164 } else
165 srcs[i] = page_address(blocks[i]) + offset;
166 }
167 raid6_call.gen_syndrome(disks, len, srcs);
168 async_tx_sync_epilog(submit);
169}
170
171/**
172 * async_gen_syndrome - asynchronously calculate a raid6 syndrome
173 * @blocks: source blocks from idx 0..disks-3, P @ disks-2 and Q @ disks-1
174 * @offset: common offset into each block (src and dest) to start transaction
175 * @disks: number of blocks (including missing P or Q, see below)
176 * @len: length of operation in bytes
177 * @submit: submission/completion modifiers
178 *
179 * General note: This routine assumes a field of GF(2^8) with a
180 * primitive polynomial of 0x11d and a generator of {02}.
181 *
182 * 'disks' note: callers can optionally omit either P or Q (but not
183 * both) from the calculation by setting blocks[disks-2] or
184 * blocks[disks-1] to NULL. When P or Q is omitted 'len' must be <=
185 * PAGE_SIZE as a temporary buffer of this size is used in the
186 * synchronous path. 'disks' always accounts for both destination
187 * buffers. If any source buffers (blocks[i] where i < disks - 2) are
188 * set to NULL those buffers will be replaced with the raid6_zero_page
189 * in the synchronous path and omitted in the hardware-asynchronous
190 * path.
191 *
192 * 'blocks' note: if submit->scribble is NULL then the contents of
193 * 'blocks' may be overwritten to perform address conversions
194 * (dma_map_page() or page_address()).
195 */
196struct dma_async_tx_descriptor *
197async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
198 size_t len, struct async_submit_ctl *submit)
199{
200 int src_cnt = disks - 2;
201 struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ,
202 &P(blocks, disks), 2,
203 blocks, src_cnt, len);
204 struct dma_device *device = chan ? chan->device : NULL;
205 dma_addr_t *dma_src = NULL;
206
207 BUG_ON(disks > 255 || !(P(blocks, disks) || Q(blocks, disks)));
208
209 if (submit->scribble)
210 dma_src = submit->scribble;
211 else if (sizeof(dma_addr_t) <= sizeof(struct page *))
212 dma_src = (dma_addr_t *) blocks;
213
214 if (dma_src && device &&
215 (src_cnt <= dma_maxpq(device, 0) ||
216 dma_maxpq(device, DMA_PREP_CONTINUE) > 0) &&
217 is_dma_pq_aligned(device, offset, 0, len)) {
218 /* run the p+q asynchronously */
219 pr_debug("%s: (async) disks: %d len: %zu\n",
220 __func__, disks, len);
221 return do_async_gen_syndrome(chan, blocks, raid6_gfexp, offset,
222 disks, len, dma_src, submit);
223 }
224
225 /* run the pq synchronously */
226 pr_debug("%s: (sync) disks: %d len: %zu\n", __func__, disks, len);
227
228 /* wait for any prerequisite operations */
229 async_tx_quiesce(&submit->depend_tx);
230
231 if (!P(blocks, disks)) {
232 P(blocks, disks) = pq_scribble_page;
233 BUG_ON(len + offset > PAGE_SIZE);
234 }
235 if (!Q(blocks, disks)) {
236 Q(blocks, disks) = pq_scribble_page;
237 BUG_ON(len + offset > PAGE_SIZE);
238 }
239 do_sync_gen_syndrome(blocks, offset, disks, len, submit);
240
241 return NULL;
242}
243EXPORT_SYMBOL_GPL(async_gen_syndrome);
244
245static inline struct dma_chan *
246pq_val_chan(struct async_submit_ctl *submit, struct page **blocks, int disks, size_t len)
247{
248 #ifdef CONFIG_ASYNC_TX_DISABLE_PQ_VAL_DMA
249 return NULL;
250 #endif
251 return async_tx_find_channel(submit, DMA_PQ_VAL, NULL, 0, blocks,
252 disks, len);
253}
254
255/**
256 * async_syndrome_val - asynchronously validate a raid6 syndrome
257 * @blocks: source blocks from idx 0..disks-3, P @ disks-2 and Q @ disks-1
258 * @offset: common offset into each block (src and dest) to start transaction
259 * @disks: number of blocks (including missing P or Q, see below)
260 * @len: length of operation in bytes
261 * @pqres: on val failure SUM_CHECK_P_RESULT and/or SUM_CHECK_Q_RESULT are set
262 * @spare: temporary result buffer for the synchronous case
263 * @submit: submission / completion modifiers
264 *
265 * The same notes from async_gen_syndrome apply to the 'blocks',
266 * and 'disks' parameters of this routine. The synchronous path
267 * requires a temporary result buffer and submit->scribble to be
268 * specified.
269 */
270struct dma_async_tx_descriptor *
271async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
272 size_t len, enum sum_check_flags *pqres, struct page *spare,
273 struct async_submit_ctl *submit)
274{
275 struct dma_chan *chan = pq_val_chan(submit, blocks, disks, len);
276 struct dma_device *device = chan ? chan->device : NULL;
277 struct dma_async_tx_descriptor *tx;
278 unsigned char coefs[disks-2];
279 enum dma_ctrl_flags dma_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
280 dma_addr_t *dma_src = NULL;
281 int src_cnt = 0;
282
283 BUG_ON(disks < 4);
284
285 if (submit->scribble)
286 dma_src = submit->scribble;
287 else if (sizeof(dma_addr_t) <= sizeof(struct page *))
288 dma_src = (dma_addr_t *) blocks;
289
290 if (dma_src && device && disks <= dma_maxpq(device, 0) &&
291 is_dma_pq_aligned(device, offset, 0, len)) {
292 struct device *dev = device->dev;
293 dma_addr_t *pq = &dma_src[disks-2];
294 int i;
295
296 pr_debug("%s: (async) disks: %d len: %zu\n",
297 __func__, disks, len);
298 if (!P(blocks, disks))
299 dma_flags |= DMA_PREP_PQ_DISABLE_P;
300 else
301 pq[0] = dma_map_page(dev, P(blocks, disks),
302 offset, len,
303 DMA_TO_DEVICE);
304 if (!Q(blocks, disks))
305 dma_flags |= DMA_PREP_PQ_DISABLE_Q;
306 else
307 pq[1] = dma_map_page(dev, Q(blocks, disks),
308 offset, len,
309 DMA_TO_DEVICE);
310
311 if (submit->flags & ASYNC_TX_FENCE)
312 dma_flags |= DMA_PREP_FENCE;
313 for (i = 0; i < disks-2; i++)
314 if (likely(blocks[i])) {
315 dma_src[src_cnt] = dma_map_page(dev, blocks[i],
316 offset, len,
317 DMA_TO_DEVICE);
318 coefs[src_cnt] = raid6_gfexp[i];
319 src_cnt++;
320 }
321
322 for (;;) {
323 tx = device->device_prep_dma_pq_val(chan, pq, dma_src,
324 src_cnt,
325 coefs,
326 len, pqres,
327 dma_flags);
328 if (likely(tx))
329 break;
330 async_tx_quiesce(&submit->depend_tx);
331 dma_async_issue_pending(chan);
332 }
333 async_tx_submit(chan, tx, submit);
334
335 return tx;
336 } else {
337 struct page *p_src = P(blocks, disks);
338 struct page *q_src = Q(blocks, disks);
339 enum async_tx_flags flags_orig = submit->flags;
340 dma_async_tx_callback cb_fn_orig = submit->cb_fn;
341 void *scribble = submit->scribble;
342 void *cb_param_orig = submit->cb_param;
343 void *p, *q, *s;
344
345 pr_debug("%s: (sync) disks: %d len: %zu\n",
346 __func__, disks, len);
347
348 /* caller must provide a temporary result buffer and
349 * allow the input parameters to be preserved
350 */
351 BUG_ON(!spare || !scribble);
352
353 /* wait for any prerequisite operations */
354 async_tx_quiesce(&submit->depend_tx);
355
356 /* recompute p and/or q into the temporary buffer and then
357 * check to see the result matches the current value
358 */
359 tx = NULL;
360 *pqres = 0;
361 if (p_src) {
362 init_async_submit(submit, ASYNC_TX_XOR_ZERO_DST, NULL,
363 NULL, NULL, scribble);
364 tx = async_xor(spare, blocks, offset, disks-2, len, submit);
365 async_tx_quiesce(&tx);
366 p = page_address(p_src) + offset;
367 s = page_address(spare) + offset;
368 *pqres |= !!memcmp(p, s, len) << SUM_CHECK_P;
369 }
370
371 if (q_src) {
372 P(blocks, disks) = NULL;
373 Q(blocks, disks) = spare;
374 init_async_submit(submit, 0, NULL, NULL, NULL, scribble);
375 tx = async_gen_syndrome(blocks, offset, disks, len, submit);
376 async_tx_quiesce(&tx);
377 q = page_address(q_src) + offset;
378 s = page_address(spare) + offset;
379 *pqres |= !!memcmp(q, s, len) << SUM_CHECK_Q;
380 }
381
382 /* restore P, Q and submit */
383 P(blocks, disks) = p_src;
384 Q(blocks, disks) = q_src;
385
386 submit->cb_fn = cb_fn_orig;
387 submit->cb_param = cb_param_orig;
388 submit->flags = flags_orig;
389 async_tx_sync_epilog(submit);
390
391 return NULL;
392 }
393}
394EXPORT_SYMBOL_GPL(async_syndrome_val);
395
396static int __init async_pq_init(void)
397{
398 pq_scribble_page = alloc_page(GFP_KERNEL);
399
400 if (pq_scribble_page)
401 return 0;
402
403 pr_err("%s: failed to allocate required spare page\n", __func__);
404
405 return -ENOMEM;
406}
407
408static void __exit async_pq_exit(void)
409{
410 put_page(pq_scribble_page);
411}
412
413module_init(async_pq_init);
414module_exit(async_pq_exit);
415
416MODULE_DESCRIPTION("asynchronous raid6 syndrome generation/validation");
417MODULE_LICENSE("GPL");