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TOMOYO Linux Cross Reference
Linux/arch/arm/common/dmabounce.c

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  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         int (*needs_bounce)(struct device *, dma_addr_t, size_t);
 84 };
 85 
 86 #ifdef STATS
 87 static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr,
 88                               char *buf)
 89 {
 90         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 91         return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n",
 92                 device_info->small.allocs,
 93                 device_info->large.allocs,
 94                 device_info->total_allocs - device_info->small.allocs -
 95                         device_info->large.allocs,
 96                 device_info->total_allocs,
 97                 device_info->map_op_count,
 98                 device_info->bounce_count);
 99 }
100 
101 static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL);
102 #endif
103 
104 
105 /* allocate a 'safe' buffer and keep track of it */
106 static inline struct safe_buffer *
107 alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
108                   size_t size, enum dma_data_direction dir)
109 {
110         struct safe_buffer *buf;
111         struct dmabounce_pool *pool;
112         struct device *dev = device_info->dev;
113         unsigned long flags;
114 
115         dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
116                 __func__, ptr, size, dir);
117 
118         if (size <= device_info->small.size) {
119                 pool = &device_info->small;
120         } else if (size <= device_info->large.size) {
121                 pool = &device_info->large;
122         } else {
123                 pool = NULL;
124         }
125 
126         buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
127         if (buf == NULL) {
128                 dev_warn(dev, "%s: kmalloc failed\n", __func__);
129                 return NULL;
130         }
131 
132         buf->ptr = ptr;
133         buf->size = size;
134         buf->direction = dir;
135         buf->pool = pool;
136 
137         if (pool) {
138                 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC,
139                                            &buf->safe_dma_addr);
140         } else {
141                 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr,
142                                                GFP_ATOMIC);
143         }
144 
145         if (buf->safe == NULL) {
146                 dev_warn(dev,
147                          "%s: could not alloc dma memory (size=%d)\n",
148                          __func__, size);
149                 kfree(buf);
150                 return NULL;
151         }
152 
153 #ifdef STATS
154         if (pool)
155                 pool->allocs++;
156         device_info->total_allocs++;
157 #endif
158 
159         write_lock_irqsave(&device_info->lock, flags);
160         list_add(&buf->node, &device_info->safe_buffers);
161         write_unlock_irqrestore(&device_info->lock, flags);
162 
163         return buf;
164 }
165 
166 /* determine if a buffer is from our "safe" pool */
167 static inline struct safe_buffer *
168 find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
169 {
170         struct safe_buffer *b, *rb = NULL;
171         unsigned long flags;
172 
173         read_lock_irqsave(&device_info->lock, flags);
174 
175         list_for_each_entry(b, &device_info->safe_buffers, node)
176                 if (b->safe_dma_addr <= safe_dma_addr &&
177                     b->safe_dma_addr + b->size > safe_dma_addr) {
178                         rb = b;
179                         break;
180                 }
181 
182         read_unlock_irqrestore(&device_info->lock, flags);
183         return rb;
184 }
185 
186 static inline void
187 free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
188 {
189         unsigned long flags;
190 
191         dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
192 
193         write_lock_irqsave(&device_info->lock, flags);
194 
195         list_del(&buf->node);
196 
197         write_unlock_irqrestore(&device_info->lock, flags);
198 
199         if (buf->pool)
200                 dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr);
201         else
202                 dma_free_coherent(device_info->dev, buf->size, buf->safe,
203                                     buf->safe_dma_addr);
204 
205         kfree(buf);
206 }
207 
208 /* ************************************************** */
209 
210 static struct safe_buffer *find_safe_buffer_dev(struct device *dev,
211                 dma_addr_t dma_addr, const char *where)
212 {
213         if (!dev || !dev->archdata.dmabounce)
214                 return NULL;
215         if (dma_mapping_error(dev, dma_addr)) {
216                 dev_err(dev, "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 int needs_bounce(struct device *dev, dma_addr_t dma_addr, size_t size)
223 {
224         if (!dev || !dev->archdata.dmabounce)
225                 return 0;
226 
227         if (dev->dma_mask) {
228                 unsigned long limit, mask = *dev->dma_mask;
229 
230                 limit = (mask + 1) & ~mask;
231                 if (limit && size > limit) {
232                         dev_err(dev, "DMA mapping too big (requested %#x "
233                                 "mask %#Lx)\n", size, *dev->dma_mask);
234                         return -E2BIG;
235                 }
236 
237                 /* Figure out if we need to bounce from the DMA mask. */
238                 if ((dma_addr | (dma_addr + size - 1)) & ~mask)
239                         return 1;
240         }
241 
242         return !!dev->archdata.dmabounce->needs_bounce(dev, dma_addr, size);
243 }
244 
245 static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
246                                     enum dma_data_direction dir,
247                                     unsigned long attrs)
248 {
249         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
250         struct safe_buffer *buf;
251 
252         if (device_info)
253                 DO_STATS ( device_info->map_op_count++ );
254 
255         buf = alloc_safe_buffer(device_info, ptr, size, dir);
256         if (buf == NULL) {
257                 dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
258                        __func__, ptr);
259                 return DMA_ERROR_CODE;
260         }
261 
262         dev_dbg(dev, "%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 || dir == DMA_BIDIRECTIONAL) &&
267             !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
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 
273         return buf->safe_dma_addr;
274 }
275 
276 static inline void unmap_single(struct device *dev, struct safe_buffer *buf,
277                                 size_t size, enum dma_data_direction dir,
278                                 unsigned long attrs)
279 {
280         BUG_ON(buf->size != size);
281         BUG_ON(buf->direction != dir);
282 
283         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
284                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
285                 buf->safe, buf->safe_dma_addr);
286 
287         DO_STATS(dev->archdata.dmabounce->bounce_count++);
288 
289         if ((dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) &&
290             !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
291                 void *ptr = buf->ptr;
292 
293                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
294                         __func__, buf->safe, ptr, size);
295                 memcpy(ptr, buf->safe, size);
296 
297                 /*
298                  * Since we may have written to a page cache page,
299                  * we need to ensure that the data will be coherent
300                  * with user mappings.
301                  */
302                 __cpuc_flush_dcache_area(ptr, size);
303         }
304         free_safe_buffer(dev->archdata.dmabounce, buf);
305 }
306 
307 /* ************************************************** */
308 
309 /*
310  * see if a buffer address is in an 'unsafe' range.  if it is
311  * allocate a 'safe' buffer and copy the unsafe buffer into it.
312  * substitute the safe buffer for the unsafe one.
313  * (basically move the buffer from an unsafe area to a safe one)
314  */
315 static dma_addr_t dmabounce_map_page(struct device *dev, struct page *page,
316                 unsigned long offset, size_t size, enum dma_data_direction dir,
317                 unsigned long attrs)
318 {
319         dma_addr_t dma_addr;
320         int ret;
321 
322         dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
323                 __func__, page, offset, size, dir);
324 
325         dma_addr = pfn_to_dma(dev, page_to_pfn(page)) + offset;
326 
327         ret = needs_bounce(dev, dma_addr, size);
328         if (ret < 0)
329                 return DMA_ERROR_CODE;
330 
331         if (ret == 0) {
332                 arm_dma_ops.sync_single_for_device(dev, dma_addr, size, dir);
333                 return dma_addr;
334         }
335 
336         if (PageHighMem(page)) {
337                 dev_err(dev, "DMA buffer bouncing of HIGHMEM pages is not supported\n");
338                 return DMA_ERROR_CODE;
339         }
340 
341         return map_single(dev, page_address(page) + offset, size, dir, attrs);
342 }
343 
344 /*
345  * see if a mapped address was really a "safe" buffer and if so, copy
346  * the data from the safe buffer back to the unsafe buffer and free up
347  * the safe buffer.  (basically return things back to the way they
348  * should be)
349  */
350 static void dmabounce_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
351                 enum dma_data_direction dir, unsigned long attrs)
352 {
353         struct safe_buffer *buf;
354 
355         dev_dbg(dev, "%s(dma=%#x,size=%d,dir=%x)\n",
356                 __func__, dma_addr, size, dir);
357 
358         buf = find_safe_buffer_dev(dev, dma_addr, __func__);
359         if (!buf) {
360                 arm_dma_ops.sync_single_for_cpu(dev, dma_addr, size, dir);
361                 return;
362         }
363 
364         unmap_single(dev, buf, size, dir, attrs);
365 }
366 
367 static int __dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
368                 size_t sz, enum dma_data_direction dir)
369 {
370         struct safe_buffer *buf;
371         unsigned long off;
372 
373         dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n",
374                 __func__, addr, sz, dir);
375 
376         buf = find_safe_buffer_dev(dev, addr, __func__);
377         if (!buf)
378                 return 1;
379 
380         off = addr - buf->safe_dma_addr;
381 
382         BUG_ON(buf->direction != dir);
383 
384         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
385                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
386                 buf->safe, buf->safe_dma_addr);
387 
388         DO_STATS(dev->archdata.dmabounce->bounce_count++);
389 
390         if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
391                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
392                         __func__, buf->safe + off, buf->ptr + off, sz);
393                 memcpy(buf->ptr + off, buf->safe + off, sz);
394         }
395         return 0;
396 }
397 
398 static void dmabounce_sync_for_cpu(struct device *dev,
399                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
400 {
401         if (!__dmabounce_sync_for_cpu(dev, handle, size, dir))
402                 return;
403 
404         arm_dma_ops.sync_single_for_cpu(dev, handle, size, dir);
405 }
406 
407 static int __dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
408                 size_t sz, enum dma_data_direction dir)
409 {
410         struct safe_buffer *buf;
411         unsigned long off;
412 
413         dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n",
414                 __func__, addr, sz, dir);
415 
416         buf = find_safe_buffer_dev(dev, addr, __func__);
417         if (!buf)
418                 return 1;
419 
420         off = addr - buf->safe_dma_addr;
421 
422         BUG_ON(buf->direction != dir);
423 
424         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
425                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
426                 buf->safe, buf->safe_dma_addr);
427 
428         DO_STATS(dev->archdata.dmabounce->bounce_count++);
429 
430         if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
431                 dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
432                         __func__,buf->ptr + off, buf->safe + off, sz);
433                 memcpy(buf->safe + off, buf->ptr + off, sz);
434         }
435         return 0;
436 }
437 
438 static void dmabounce_sync_for_device(struct device *dev,
439                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
440 {
441         if (!__dmabounce_sync_for_device(dev, handle, size, dir))
442                 return;
443 
444         arm_dma_ops.sync_single_for_device(dev, handle, size, dir);
445 }
446 
447 static int dmabounce_set_mask(struct device *dev, u64 dma_mask)
448 {
449         if (dev->archdata.dmabounce)
450                 return 0;
451 
452         return arm_dma_ops.set_dma_mask(dev, dma_mask);
453 }
454 
455 static struct dma_map_ops dmabounce_ops = {
456         .alloc                  = arm_dma_alloc,
457         .free                   = arm_dma_free,
458         .mmap                   = arm_dma_mmap,
459         .get_sgtable            = arm_dma_get_sgtable,
460         .map_page               = dmabounce_map_page,
461         .unmap_page             = dmabounce_unmap_page,
462         .sync_single_for_cpu    = dmabounce_sync_for_cpu,
463         .sync_single_for_device = dmabounce_sync_for_device,
464         .map_sg                 = arm_dma_map_sg,
465         .unmap_sg               = arm_dma_unmap_sg,
466         .sync_sg_for_cpu        = arm_dma_sync_sg_for_cpu,
467         .sync_sg_for_device     = arm_dma_sync_sg_for_device,
468         .set_dma_mask           = dmabounce_set_mask,
469 };
470 
471 static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
472                 const char *name, unsigned long size)
473 {
474         pool->size = size;
475         DO_STATS(pool->allocs = 0);
476         pool->pool = dma_pool_create(name, dev, size,
477                                      0 /* byte alignment */,
478                                      0 /* no page-crossing issues */);
479 
480         return pool->pool ? 0 : -ENOMEM;
481 }
482 
483 int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
484                 unsigned long large_buffer_size,
485                 int (*needs_bounce_fn)(struct device *, dma_addr_t, size_t))
486 {
487         struct dmabounce_device_info *device_info;
488         int ret;
489 
490         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
491         if (!device_info) {
492                 dev_err(dev,
493                         "Could not allocated dmabounce_device_info\n");
494                 return -ENOMEM;
495         }
496 
497         ret = dmabounce_init_pool(&device_info->small, dev,
498                                   "small_dmabounce_pool", small_buffer_size);
499         if (ret) {
500                 dev_err(dev,
501                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
502                         small_buffer_size);
503                 goto err_free;
504         }
505 
506         if (large_buffer_size) {
507                 ret = dmabounce_init_pool(&device_info->large, dev,
508                                           "large_dmabounce_pool",
509                                           large_buffer_size);
510                 if (ret) {
511                         dev_err(dev,
512                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
513                                 large_buffer_size);
514                         goto err_destroy;
515                 }
516         }
517 
518         device_info->dev = dev;
519         INIT_LIST_HEAD(&device_info->safe_buffers);
520         rwlock_init(&device_info->lock);
521         device_info->needs_bounce = needs_bounce_fn;
522 
523 #ifdef STATS
524         device_info->total_allocs = 0;
525         device_info->map_op_count = 0;
526         device_info->bounce_count = 0;
527         device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
528 #endif
529 
530         dev->archdata.dmabounce = device_info;
531         set_dma_ops(dev, &dmabounce_ops);
532 
533         dev_info(dev, "dmabounce: registered device\n");
534 
535         return 0;
536 
537  err_destroy:
538         dma_pool_destroy(device_info->small.pool);
539  err_free:
540         kfree(device_info);
541         return ret;
542 }
543 EXPORT_SYMBOL(dmabounce_register_dev);
544 
545 void dmabounce_unregister_dev(struct device *dev)
546 {
547         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
548 
549         dev->archdata.dmabounce = NULL;
550         set_dma_ops(dev, NULL);
551 
552         if (!device_info) {
553                 dev_warn(dev,
554                          "Never registered with dmabounce but attempting"
555                          "to unregister!\n");
556                 return;
557         }
558 
559         if (!list_empty(&device_info->safe_buffers)) {
560                 dev_err(dev,
561                         "Removing from dmabounce with pending buffers!\n");
562                 BUG();
563         }
564 
565         if (device_info->small.pool)
566                 dma_pool_destroy(device_info->small.pool);
567         if (device_info->large.pool)
568                 dma_pool_destroy(device_info->large.pool);
569 
570 #ifdef STATS
571         if (device_info->attr_res == 0)
572                 device_remove_file(dev, &dev_attr_dmabounce_stats);
573 #endif
574 
575         kfree(device_info);
576 
577         dev_info(dev, "dmabounce: device unregistered\n");
578 }
579 EXPORT_SYMBOL(dmabounce_unregister_dev);
580 
581 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
582 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
583 MODULE_LICENSE("GPL");
584 

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