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defxx: Use __maybe_unused rather than a local hack
[wrt350n-kernel.git] / arch / arm / common / dmabounce.c
blobb36b1e8a105d39d61d978969262787b9bbfd88a5
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/device.h>
29 #include <linux/dma-mapping.h>
30 #include <linux/dmapool.h>
31 #include <linux/list.h>
32
33 #include <asm/cacheflush.h>
34
35 #undef STATS
36
37 #ifdef STATS
38 #define DO_STATS(X) do { X ; } while (0)
39 #else
40 #define DO_STATS(X) do { } while (0)
41 #endif
42
43 /* ************************************************** */
44
45 struct safe_buffer {
46 struct list_head node;
47
48 /* original request */
49 void *ptr;
50 size_t size;
51 int direction;
52
53 /* safe buffer info */
54 struct dmabounce_pool *pool;
55 void *safe;
56 dma_addr_t safe_dma_addr;
57 };
58
59 struct dmabounce_pool {
60 unsigned long size;
61 struct dma_pool *pool;
62 #ifdef STATS
63 unsigned long allocs;
64 #endif
65 };
66
67 struct dmabounce_device_info {
68 struct device *dev;
69 struct list_head safe_buffers;
70 #ifdef STATS
71 unsigned long total_allocs;
72 unsigned long map_op_count;
73 unsigned long bounce_count;
74 int attr_res;
75 #endif
76 struct dmabounce_pool small;
77 struct dmabounce_pool large;
78
79 rwlock_t lock;
80 };
81
82 #ifdef STATS
83 static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr,
84 char *buf)
85 {
86 struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
87 return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n",
88 device_info->small.allocs,
89 device_info->large.allocs,
90 device_info->total_allocs - device_info->small.allocs -
91 device_info->large.allocs,
92 device_info->total_allocs,
93 device_info->map_op_count,
94 device_info->bounce_count);
95 }
96
97 static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL);
98 #endif
99
100
101 /* allocate a 'safe' buffer and keep track of it */
102 static inline struct safe_buffer *
103 alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
104 size_t size, enum dma_data_direction dir)
105 {
106 struct safe_buffer *buf;
107 struct dmabounce_pool *pool;
108 struct device *dev = device_info->dev;
109 unsigned long flags;
110
111 dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
112 __func__, ptr, size, dir);
113
114 if (size <= device_info->small.size) {
115 pool = &device_info->small;
116 } else if (size <= device_info->large.size) {
117 pool = &device_info->large;
118 } else {
119 pool = NULL;
120 }
121
122 buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
123 if (buf == NULL) {
124 dev_warn(dev, "%s: kmalloc failed\n", __func__);
125 return NULL;
126 }
127
128 buf->ptr = ptr;
129 buf->size = size;
130 buf->direction = dir;
131 buf->pool = pool;
132
133 if (pool) {
134 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC,
135 &buf->safe_dma_addr);
136 } else {
137 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr,
138 GFP_ATOMIC);
139 }
140
141 if (buf->safe == NULL) {
142 dev_warn(dev,
143 "%s: could not alloc dma memory (size=%d)\n",
144 __func__, size);
145 kfree(buf);
146 return NULL;
147 }
148
149 #ifdef STATS
150 if (pool)
151 pool->allocs++;
152 device_info->total_allocs++;
153 #endif
154
155 write_lock_irqsave(&device_info->lock, flags);
156
157 list_add(&buf->node, &device_info->safe_buffers);
158
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 inline dma_addr_t
208 map_single(struct device *dev, void *ptr, size_t size,
209 enum dma_data_direction dir)
210 {
211 struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
212 dma_addr_t dma_addr;
213 int needs_bounce = 0;
214
215 if (device_info)
216 DO_STATS ( device_info->map_op_count++ );
217
218 dma_addr = virt_to_dma(dev, ptr);
219
220 if (dev->dma_mask) {
221 unsigned long mask = *dev->dma_mask;
222 unsigned long limit;
223
224 limit = (mask + 1) & ~mask;
225 if (limit && size > limit) {
226 dev_err(dev, "DMA mapping too big (requested %#x "
227 "mask %#Lx)\n", size, *dev->dma_mask);
228 return ~0;
229 }
230
231 /*
232 * Figure out if we need to bounce from the DMA mask.
233 */
234 needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask;
235 }
236
237 if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr, size))) {
238 struct safe_buffer *buf;
239
240 buf = alloc_safe_buffer(device_info, ptr, size, dir);
241 if (buf == 0) {
242 dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
243 __func__, ptr);
244 return 0;
245 }
246
247 dev_dbg(dev,
248 "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
249 __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr),
250 buf->safe, (void *) buf->safe_dma_addr);
251
252 if ((dir == DMA_TO_DEVICE) ||
253 (dir == DMA_BIDIRECTIONAL)) {
254 dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
255 __func__, ptr, buf->safe, size);
256 memcpy(buf->safe, ptr, size);
257 }
258 ptr = buf->safe;
259
260 dma_addr = buf->safe_dma_addr;
261 } else {
262 /*
263 * We don't need to sync the DMA buffer since
264 * it was allocated via the coherent allocators.
265 */
266 consistent_sync(ptr, size, dir);
267 }
268
269 return dma_addr;
270 }
271
272 static inline void
273 unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
274 enum dma_data_direction dir)
275 {
276 struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
277 struct safe_buffer *buf = NULL;
278
279 /*
280 * Trying to unmap an invalid mapping
281 */
282 if (dma_mapping_error(dma_addr)) {
283 dev_err(dev, "Trying to unmap invalid mapping\n");
284 return;
285 }
286
287 if (device_info)
288 buf = find_safe_buffer(device_info, dma_addr);
289
290 if (buf) {
291 BUG_ON(buf->size != size);
292
293 dev_dbg(dev,
294 "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
295 __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr),
296 buf->safe, (void *) buf->safe_dma_addr);
297
298 DO_STATS ( device_info->bounce_count++ );
299
300 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
301 void *ptr = buf->ptr;
302
303 dev_dbg(dev,
304 "%s: copy back safe %p to unsafe %p size %d\n",
305 __func__, buf->safe, ptr, size);
306 memcpy(ptr, buf->safe, size);
307
308 /*
309 * DMA buffers must have the same cache properties
310 * as if they were really used for DMA - which means
311 * data must be written back to RAM. Note that
312 * we don't use dmac_flush_range() here for the
313 * bidirectional case because we know the cache
314 * lines will be coherent with the data written.
315 */
316 dmac_clean_range(ptr, ptr + size);
317 outer_clean_range(__pa(ptr), __pa(ptr) + size);
318 }
319 free_safe_buffer(device_info, buf);
320 }
321 }
322
323 static inline void
324 sync_single(struct device *dev, dma_addr_t dma_addr, size_t size,
325 enum dma_data_direction dir)
326 {
327 struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
328 struct safe_buffer *buf = NULL;
329
330 if (device_info)
331 buf = find_safe_buffer(device_info, dma_addr);
332
333 if (buf) {
334 /*
335 * Both of these checks from original code need to be
336 * commented out b/c some drivers rely on the following:
337 *
338 * 1) Drivers may map a large chunk of memory into DMA space
339 * but only sync a small portion of it. Good example is
340 * allocating a large buffer, mapping it, and then
341 * breaking it up into small descriptors. No point
342 * in syncing the whole buffer if you only have to
343 * touch one descriptor.
344 *
345 * 2) Buffers that are mapped as DMA_BIDIRECTIONAL are
346 * usually only synced in one dir at a time.
347 *
348 * See drivers/net/eepro100.c for examples of both cases.
349 *
350 * -ds
351 *
352 * BUG_ON(buf->size != size);
353 * BUG_ON(buf->direction != dir);
354 */
355
356 dev_dbg(dev,
357 "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
358 __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr),
359 buf->safe, (void *) buf->safe_dma_addr);
360
361 DO_STATS ( device_info->bounce_count++ );
362
363 switch (dir) {
364 case DMA_FROM_DEVICE:
365 dev_dbg(dev,
366 "%s: copy back safe %p to unsafe %p size %d\n",
367 __func__, buf->safe, buf->ptr, size);
368 memcpy(buf->ptr, buf->safe, size);
369 break;
370 case DMA_TO_DEVICE:
371 dev_dbg(dev,
372 "%s: copy out unsafe %p to safe %p, size %d\n",
373 __func__,buf->ptr, buf->safe, size);
374 memcpy(buf->safe, buf->ptr, size);
375 break;
376 case DMA_BIDIRECTIONAL:
377 BUG(); /* is this allowed? what does it mean? */
378 default:
379 BUG();
380 }
381 /*
382 * No need to sync the safe buffer - it was allocated
383 * via the coherent allocators.
384 */
385 } else {
386 consistent_sync(dma_to_virt(dev, dma_addr), size, dir);
387 }
388 }
389
390 /* ************************************************** */
391
392 /*
393 * see if a buffer address is in an 'unsafe' range. if it is
394 * allocate a 'safe' buffer and copy the unsafe buffer into it.
395 * substitute the safe buffer for the unsafe one.
396 * (basically move the buffer from an unsafe area to a safe one)
397 */
398 dma_addr_t
399 dma_map_single(struct device *dev, void *ptr, size_t size,
400 enum dma_data_direction dir)
401 {
402 dma_addr_t dma_addr;
403
404 dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
405 __func__, ptr, size, dir);
406
407 BUG_ON(dir == DMA_NONE);
408
409 dma_addr = map_single(dev, ptr, size, dir);
410
411 return dma_addr;
412 }
413
414 /*
415 * see if a mapped address was really a "safe" buffer and if so, copy
416 * the data from the safe buffer back to the unsafe buffer and free up
417 * the safe buffer. (basically return things back to the way they
418 * should be)
419 */
420
421 void
422 dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
423 enum dma_data_direction dir)
424 {
425 dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
426 __func__, (void *) dma_addr, size, dir);
427
428 BUG_ON(dir == DMA_NONE);
429
430 unmap_single(dev, dma_addr, size, dir);
431 }
432
433 int
434 dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
435 enum dma_data_direction dir)
436 {
437 int i;
438
439 dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
440 __func__, sg, nents, dir);
441
442 BUG_ON(dir == DMA_NONE);
443
444 for (i = 0; i < nents; i++, sg++) {
445 struct page *page = sg->page;
446 unsigned int offset = sg->offset;
447 unsigned int length = sg->length;
448 void *ptr = page_address(page) + offset;
449
450 sg->dma_address =
451 map_single(dev, ptr, length, dir);
452 }
453
454 return nents;
455 }
456
457 void
458 dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
459 enum dma_data_direction dir)
460 {
461 int i;
462
463 dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
464 __func__, sg, nents, dir);
465
466 BUG_ON(dir == DMA_NONE);
467
468 for (i = 0; i < nents; i++, sg++) {
469 dma_addr_t dma_addr = sg->dma_address;
470 unsigned int length = sg->length;
471
472 unmap_single(dev, dma_addr, length, dir);
473 }
474 }
475
476 void
477 dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr, size_t size,
478 enum dma_data_direction dir)
479 {
480 dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
481 __func__, (void *) dma_addr, size, dir);
482
483 sync_single(dev, dma_addr, size, dir);
484 }
485
486 void
487 dma_sync_single_for_device(struct device *dev, dma_addr_t dma_addr, size_t size,
488 enum dma_data_direction dir)
489 {
490 dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
491 __func__, (void *) dma_addr, size, dir);
492
493 sync_single(dev, dma_addr, size, dir);
494 }
495
496 void
497 dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents,
498 enum dma_data_direction dir)
499 {
500 int i;
501
502 dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
503 __func__, sg, nents, dir);
504
505 BUG_ON(dir == DMA_NONE);
506
507 for (i = 0; i < nents; i++, sg++) {
508 dma_addr_t dma_addr = sg->dma_address;
509 unsigned int length = sg->length;
510
511 sync_single(dev, dma_addr, length, dir);
512 }
513 }
514
515 void
516 dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents,
517 enum dma_data_direction dir)
518 {
519 int i;
520
521 dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
522 __func__, sg, nents, dir);
523
524 BUG_ON(dir == DMA_NONE);
525
526 for (i = 0; i < nents; i++, sg++) {
527 dma_addr_t dma_addr = sg->dma_address;
528 unsigned int length = sg->length;
529
530 sync_single(dev, dma_addr, length, dir);
531 }
532 }
533
534 static int
535 dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev, const char *name,
536 unsigned long size)
537 {
538 pool->size = size;
539 DO_STATS(pool->allocs = 0);
540 pool->pool = dma_pool_create(name, dev, size,
541 0 /* byte alignment */,
542 0 /* no page-crossing issues */);
543
544 return pool->pool ? 0 : -ENOMEM;
545 }
546
547 int
548 dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
549 unsigned long large_buffer_size)
550 {
551 struct dmabounce_device_info *device_info;
552 int ret;
553
554 device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
555 if (!device_info) {
556 printk(KERN_ERR
557 "Could not allocated dmabounce_device_info for %s",
558 dev->bus_id);
559 return -ENOMEM;
560 }
561
562 ret = dmabounce_init_pool(&device_info->small, dev,
563 "small_dmabounce_pool", small_buffer_size);
564 if (ret) {
565 dev_err(dev,
566 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
567 small_buffer_size);
568 goto err_free;
569 }
570
571 if (large_buffer_size) {
572 ret = dmabounce_init_pool(&device_info->large, dev,
573 "large_dmabounce_pool",
574 large_buffer_size);
575 if (ret) {
576 dev_err(dev,
577 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
578 large_buffer_size);
579 goto err_destroy;
580 }
581 }
582
583 device_info->dev = dev;
584 INIT_LIST_HEAD(&device_info->safe_buffers);
585 rwlock_init(&device_info->lock);
586
587 #ifdef STATS
588 device_info->total_allocs = 0;
589 device_info->map_op_count = 0;
590 device_info->bounce_count = 0;
591 device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
592 #endif
593
594 dev->archdata.dmabounce = device_info;
595
596 printk(KERN_INFO "dmabounce: registered device %s on %s bus\n",
597 dev->bus_id, dev->bus->name);
598
599 return 0;
600
601 err_destroy:
602 dma_pool_destroy(device_info->small.pool);
603 err_free:
604 kfree(device_info);
605 return ret;
606 }
607
608 void
609 dmabounce_unregister_dev(struct device *dev)
610 {
611 struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
612
613 dev->archdata.dmabounce = NULL;
614
615 if (!device_info) {
616 printk(KERN_WARNING
617 "%s: Never registered with dmabounce but attempting" \
618 "to unregister!\n", dev->bus_id);
619 return;
620 }
621
622 if (!list_empty(&device_info->safe_buffers)) {
623 printk(KERN_ERR
624 "%s: Removing from dmabounce with pending buffers!\n",
625 dev->bus_id);
626 BUG();
627 }
628
629 if (device_info->small.pool)
630 dma_pool_destroy(device_info->small.pool);
631 if (device_info->large.pool)
632 dma_pool_destroy(device_info->large.pool);
633
634 #ifdef STATS
635 if (device_info->attr_res == 0)
636 device_remove_file(dev, &dev_attr_dmabounce_stats);
637 #endif
638
639 kfree(device_info);
640
641 printk(KERN_INFO "dmabounce: device %s on %s bus unregistered\n",
642 dev->bus_id, dev->bus->name);
643 }
644
645
646 EXPORT_SYMBOL(dma_map_single);
647 EXPORT_SYMBOL(dma_unmap_single);
648 EXPORT_SYMBOL(dma_map_sg);
649 EXPORT_SYMBOL(dma_unmap_sg);
650 EXPORT_SYMBOL(dma_sync_single_for_cpu);
651 EXPORT_SYMBOL(dma_sync_single_for_device);
652 EXPORT_SYMBOL(dma_sync_sg);
653 EXPORT_SYMBOL(dmabounce_register_dev);
654 EXPORT_SYMBOL(dmabounce_unregister_dev);
655
656 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
657 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
658 MODULE_LICENSE("GPL");
WRT350N Kernel Patches