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nilfs2: fix oopses with doubly mounted snapshots
[linux-2.6/mini2440.git] / arch / arm / common / dmabounce.c
blob734ac9135998d9efffb0a1b84c3a82416b31d325
1 /*
2 * arch/arm/common/dmabounce.c
3 *
4 * Special dma_{map/unmap/dma_sync}_* routines for systems that have
5 * limited DMA windows. These functions utilize bounce buffers to
6 * copy data to/from buffers located outside the DMA region. This
7 * only works for systems in which DMA memory is at the bottom of
8 * RAM, the remainder of memory is at the top and the DMA memory
9 * can be marked as ZONE_DMA. Anything beyond that such as discontiguous
10 * DMA windows will require custom implementations that reserve memory
11 * areas at early bootup.
12 *
13 * Original version by Brad Parker (brad@heeltoe.com)
14 * Re-written by Christopher Hoover <ch@murgatroid.com>
15 * Made generic by Deepak Saxena <dsaxena@plexity.net>
16 *
17 * Copyright (C) 2002 Hewlett Packard Company.
18 * Copyright (C) 2004 MontaVista Software, Inc.
19 *
20 * This program is free software; you can redistribute it and/or
21 * modify it under the terms of the GNU General Public License
22 * version 2 as published by the Free Software Foundation.
23 */
24
25 #include <linux/module.h>
26 #include <linux/init.h>
27 #include <linux/slab.h>
28 #include <linux/page-flags.h>
29 #include <linux/device.h>
30 #include <linux/dma-mapping.h>
31 #include <linux/dmapool.h>
32 #include <linux/list.h>
33 #include <linux/scatterlist.h>
34
35 #include <asm/cacheflush.h>
36
37 #undef STATS
38
39 #ifdef STATS
40 #define DO_STATS(X) do { X ; } while (0)
41 #else
42 #define DO_STATS(X) do { } while (0)
43 #endif
44
45 /* ************************************************** */
46
47 struct safe_buffer {
48 struct list_head node;
49
50 /* original request */
51 void *ptr;
52 size_t size;
53 int direction;
54
55 /* safe buffer info */
56 struct dmabounce_pool *pool;
57 void *safe;
58 dma_addr_t safe_dma_addr;
59 };
60
61 struct dmabounce_pool {
62 unsigned long size;
63 struct dma_pool *pool;
64 #ifdef STATS
65 unsigned long allocs;
66 #endif
67 };
68
69 struct dmabounce_device_info {
70 struct device *dev;
71 struct list_head safe_buffers;
72 #ifdef STATS
73 unsigned long total_allocs;
74 unsigned long map_op_count;
75 unsigned long bounce_count;
76 int attr_res;
77 #endif
78 struct dmabounce_pool small;
79 struct dmabounce_pool large;
80
81 rwlock_t lock;
82 };
83
84 #ifdef STATS
85 static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr,
86 char *buf)
87 {
88 struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
89 return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n",
90 device_info->small.allocs,
91 device_info->large.allocs,
92 device_info->total_allocs - device_info->small.allocs -
93 device_info->large.allocs,
94 device_info->total_allocs,
95 device_info->map_op_count,
96 device_info->bounce_count);
97 }
98
99 static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL);
100 #endif
101
102
103 /* allocate a 'safe' buffer and keep track of it */
104 static inline struct safe_buffer *
105 alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
106 size_t size, enum dma_data_direction dir)
107 {
108 struct safe_buffer *buf;
109 struct dmabounce_pool *pool;
110 struct device *dev = device_info->dev;
111 unsigned long flags;
112
113 dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
114 __func__, ptr, size, dir);
115
116 if (size <= device_info->small.size) {
117 pool = &device_info->small;
118 } else if (size <= device_info->large.size) {
119 pool = &device_info->large;
120 } else {
121 pool = NULL;
122 }
123
124 buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
125 if (buf == NULL) {
126 dev_warn(dev, "%s: kmalloc failed\n", __func__);
127 return NULL;
128 }
129
130 buf->ptr = ptr;
131 buf->size = size;
132 buf->direction = dir;
133 buf->pool = pool;
134
135 if (pool) {
136 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC,
137 &buf->safe_dma_addr);
138 } else {
139 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr,
140 GFP_ATOMIC);
141 }
142
143 if (buf->safe == NULL) {
144 dev_warn(dev,
145 "%s: could not alloc dma memory (size=%d)\n",
146 __func__, size);
147 kfree(buf);
148 return NULL;
149 }
150
151 #ifdef STATS
152 if (pool)
153 pool->allocs++;
154 device_info->total_allocs++;
155 #endif
156
157 write_lock_irqsave(&device_info->lock, flags);
158 list_add(&buf->node, &device_info->safe_buffers);
159 write_unlock_irqrestore(&device_info->lock, flags);
160
161 return buf;
162 }
163
164 /* determine if a buffer is from our "safe" pool */
165 static inline struct safe_buffer *
166 find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
167 {
168 struct safe_buffer *b, *rb = NULL;
169 unsigned long flags;
170
171 read_lock_irqsave(&device_info->lock, flags);
172
173 list_for_each_entry(b, &device_info->safe_buffers, node)
174 if (b->safe_dma_addr == safe_dma_addr) {
175 rb = b;
176 break;
177 }
178
179 read_unlock_irqrestore(&device_info->lock, flags);
180 return rb;
181 }
182
183 static inline void
184 free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
185 {
186 unsigned long flags;
187
188 dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
189
190 write_lock_irqsave(&device_info->lock, flags);
191
192 list_del(&buf->node);
193
194 write_unlock_irqrestore(&device_info->lock, flags);
195
196 if (buf->pool)
197 dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr);
198 else
199 dma_free_coherent(device_info->dev, buf->size, buf->safe,
200 buf->safe_dma_addr);
201
202 kfree(buf);
203 }
204
205 /* ************************************************** */
206
207 static struct safe_buffer *find_safe_buffer_dev(struct device *dev,
208 dma_addr_t dma_addr, const char *where)
209 {
210 if (!dev || !dev->archdata.dmabounce)
211 return NULL;
212 if (dma_mapping_error(dev, dma_addr)) {
213 if (dev)
214 dev_err(dev, "Trying to %s invalid mapping\n", where);
215 else
216 pr_err("unknown device: Trying to %s invalid mapping\n", where);
217 return NULL;
218 }
219 return find_safe_buffer(dev->archdata.dmabounce, dma_addr);
220 }
221
222 static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
223 enum dma_data_direction dir)
224 {
225 struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
226 dma_addr_t dma_addr;
227 int needs_bounce = 0;
228
229 if (device_info)
230 DO_STATS ( device_info->map_op_count++ );
231
232 dma_addr = virt_to_dma(dev, ptr);
233
234 if (dev->dma_mask) {
235 unsigned long mask = *dev->dma_mask;
236 unsigned long limit;
237
238 limit = (mask + 1) & ~mask;
239 if (limit && size > limit) {
240 dev_err(dev, "DMA mapping too big (requested %#x "
241 "mask %#Lx)\n", size, *dev->dma_mask);
242 return ~0;
243 }
244
245 /*
246 * Figure out if we need to bounce from the DMA mask.
247 */
248 needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask;
249 }
250
251 if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr, size))) {
252 struct safe_buffer *buf;
253
254 buf = alloc_safe_buffer(device_info, ptr, size, dir);
255 if (buf == 0) {
256 dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
257 __func__, ptr);
258 return 0;
259 }
260
261 dev_dbg(dev,
262 "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
263 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
264 buf->safe, buf->safe_dma_addr);
265
266 if ((dir == DMA_TO_DEVICE) ||
267 (dir == DMA_BIDIRECTIONAL)) {
268 dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
269 __func__, ptr, buf->safe, size);
270 memcpy(buf->safe, ptr, size);
271 }
272 ptr = buf->safe;
273
274 dma_addr = buf->safe_dma_addr;
275 } else {
276 /*
277 * We don't need to sync the DMA buffer since
278 * it was allocated via the coherent allocators.
279 */
280 dma_cache_maint(ptr, size, dir);
281 }
282
283 return dma_addr;
284 }
285
286 static inline void unmap_single(struct device *dev, dma_addr_t dma_addr,
287 size_t size, enum dma_data_direction dir)
288 {
289 struct safe_buffer *buf = find_safe_buffer_dev(dev, dma_addr, "unmap");
290
291 if (buf) {
292 BUG_ON(buf->size != size);
293 BUG_ON(buf->direction != dir);
294
295 dev_dbg(dev,
296 "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
297 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
298 buf->safe, buf->safe_dma_addr);
299
300 DO_STATS(dev->archdata.dmabounce->bounce_count++);
301
302 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
303 void *ptr = buf->ptr;
304
305 dev_dbg(dev,
306 "%s: copy back safe %p to unsafe %p size %d\n",
307 __func__, buf->safe, ptr, size);
308 memcpy(ptr, buf->safe, size);
309
310 /*
311 * DMA buffers must have the same cache properties
312 * as if they were really used for DMA - which means
313 * data must be written back to RAM. Note that
314 * we don't use dmac_flush_range() here for the
315 * bidirectional case because we know the cache
316 * lines will be coherent with the data written.
317 */
318 dmac_clean_range(ptr, ptr + size);
319 outer_clean_range(__pa(ptr), __pa(ptr) + size);
320 }
321 free_safe_buffer(dev->archdata.dmabounce, buf);
322 }
323 }
324
325 /* ************************************************** */
326
327 /*
328 * see if a buffer address is in an 'unsafe' range. if it is
329 * allocate a 'safe' buffer and copy the unsafe buffer into it.
330 * substitute the safe buffer for the unsafe one.
331 * (basically move the buffer from an unsafe area to a safe one)
332 */
333 dma_addr_t dma_map_single(struct device *dev, void *ptr, size_t size,
334 enum dma_data_direction dir)
335 {
336 dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
337 __func__, ptr, size, dir);
338
339 BUG_ON(!valid_dma_direction(dir));
340
341 return map_single(dev, ptr, size, dir);
342 }
343 EXPORT_SYMBOL(dma_map_single);
344
345 dma_addr_t dma_map_page(struct device *dev, struct page *page,
346 unsigned long offset, size_t size, enum dma_data_direction dir)
347 {
348 dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
349 __func__, page, offset, size, dir);
350
351 BUG_ON(!valid_dma_direction(dir));
352
353 if (PageHighMem(page)) {
354 dev_err(dev, "DMA buffer bouncing of HIGHMEM pages "
355 "is not supported\n");
356 return ~0;
357 }
358
359 return map_single(dev, page_address(page) + offset, size, dir);
360 }
361 EXPORT_SYMBOL(dma_map_page);
362
363 /*
364 * see if a mapped address was really a "safe" buffer and if so, copy
365 * the data from the safe buffer back to the unsafe buffer and free up
366 * the safe buffer. (basically return things back to the way they
367 * should be)
368 */
369
370 void dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
371 enum dma_data_direction dir)
372 {
373 dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
374 __func__, (void *) dma_addr, size, dir);
375
376 unmap_single(dev, dma_addr, size, dir);
377 }
378 EXPORT_SYMBOL(dma_unmap_single);
379
380 int dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
381 unsigned long off, size_t sz, enum dma_data_direction dir)
382 {
383 struct safe_buffer *buf;
384
385 dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
386 __func__, addr, off, sz, dir);
387
388 buf = find_safe_buffer_dev(dev, addr, __func__);
389 if (!buf)
390 return 1;
391
392 BUG_ON(buf->direction != dir);
393
394 dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
395 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
396 buf->safe, buf->safe_dma_addr);
397
398 DO_STATS(dev->archdata.dmabounce->bounce_count++);
399
400 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
401 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
402 __func__, buf->safe + off, buf->ptr + off, sz);
403 memcpy(buf->ptr + off, buf->safe + off, sz);
404 }
405 return 0;
406 }
407 EXPORT_SYMBOL(dmabounce_sync_for_cpu);
408
409 int dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
410 unsigned long off, size_t sz, enum dma_data_direction dir)
411 {
412 struct safe_buffer *buf;
413
414 dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
415 __func__, addr, off, sz, dir);
416
417 buf = find_safe_buffer_dev(dev, addr, __func__);
418 if (!buf)
419 return 1;
420
421 BUG_ON(buf->direction != dir);
422
423 dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
424 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
425 buf->safe, buf->safe_dma_addr);
426
427 DO_STATS(dev->archdata.dmabounce->bounce_count++);
428
429 if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
430 dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
431 __func__,buf->ptr + off, buf->safe + off, sz);
432 memcpy(buf->safe + off, buf->ptr + off, sz);
433 }
434 return 0;
435 }
436 EXPORT_SYMBOL(dmabounce_sync_for_device);
437
438 static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
439 const char *name, unsigned long size)
440 {
441 pool->size = size;
442 DO_STATS(pool->allocs = 0);
443 pool->pool = dma_pool_create(name, dev, size,
444 0 /* byte alignment */,
445 0 /* no page-crossing issues */);
446
447 return pool->pool ? 0 : -ENOMEM;
448 }
449
450 int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
451 unsigned long large_buffer_size)
452 {
453 struct dmabounce_device_info *device_info;
454 int ret;
455
456 device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
457 if (!device_info) {
458 dev_err(dev,
459 "Could not allocated dmabounce_device_info\n");
460 return -ENOMEM;
461 }
462
463 ret = dmabounce_init_pool(&device_info->small, dev,
464 "small_dmabounce_pool", small_buffer_size);
465 if (ret) {
466 dev_err(dev,
467 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
468 small_buffer_size);
469 goto err_free;
470 }
471
472 if (large_buffer_size) {
473 ret = dmabounce_init_pool(&device_info->large, dev,
474 "large_dmabounce_pool",
475 large_buffer_size);
476 if (ret) {
477 dev_err(dev,
478 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
479 large_buffer_size);
480 goto err_destroy;
481 }
482 }
483
484 device_info->dev = dev;
485 INIT_LIST_HEAD(&device_info->safe_buffers);
486 rwlock_init(&device_info->lock);
487
488 #ifdef STATS
489 device_info->total_allocs = 0;
490 device_info->map_op_count = 0;
491 device_info->bounce_count = 0;
492 device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
493 #endif
494
495 dev->archdata.dmabounce = device_info;
496
497 dev_info(dev, "dmabounce: registered device\n");
498
499 return 0;
500
501 err_destroy:
502 dma_pool_destroy(device_info->small.pool);
503 err_free:
504 kfree(device_info);
505 return ret;
506 }
507 EXPORT_SYMBOL(dmabounce_register_dev);
508
509 void dmabounce_unregister_dev(struct device *dev)
510 {
511 struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
512
513 dev->archdata.dmabounce = NULL;
514
515 if (!device_info) {
516 dev_warn(dev,
517 "Never registered with dmabounce but attempting"
518 "to unregister!\n");
519 return;
520 }
521
522 if (!list_empty(&device_info->safe_buffers)) {
523 dev_err(dev,
524 "Removing from dmabounce with pending buffers!\n");
525 BUG();
526 }
527
528 if (device_info->small.pool)
529 dma_pool_destroy(device_info->small.pool);
530 if (device_info->large.pool)
531 dma_pool_destroy(device_info->large.pool);
532
533 #ifdef STATS
534 if (device_info->attr_res == 0)
535 device_remove_file(dev, &dev_attr_dmabounce_stats);
536 #endif
537
538 kfree(device_info);
539
540 dev_info(dev, "dmabounce: device unregistered\n");
541 }
542 EXPORT_SYMBOL(dmabounce_unregister_dev);
543
544 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
545 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
546 MODULE_LICENSE("GPL");
Support for the Chinese Samsung S3C2440 based development boards