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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 {
248         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
249         struct safe_buffer *buf;
250 
251         if (device_info)
252                 DO_STATS ( device_info->map_op_count++ );
253 
254         buf = alloc_safe_buffer(device_info, ptr, size, dir);
255         if (buf == NULL) {
256                 dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
257                        __func__, ptr);
258                 return DMA_ERROR_CODE;
259         }
260 
261         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
262                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
263                 buf->safe, buf->safe_dma_addr);
264 
265         if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
266                 dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
267                         __func__, ptr, buf->safe, size);
268                 memcpy(buf->safe, ptr, size);
269         }
270 
271         return buf->safe_dma_addr;
272 }
273 
274 static inline void unmap_single(struct device *dev, struct safe_buffer *buf,
275                 size_t size, enum dma_data_direction dir)
276 {
277         BUG_ON(buf->size != size);
278         BUG_ON(buf->direction != dir);
279 
280         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
281                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
282                 buf->safe, buf->safe_dma_addr);
283 
284         DO_STATS(dev->archdata.dmabounce->bounce_count++);
285 
286         if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
287                 void *ptr = buf->ptr;
288 
289                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
290                         __func__, buf->safe, ptr, size);
291                 memcpy(ptr, buf->safe, size);
292 
293                 /*
294                  * Since we may have written to a page cache page,
295                  * we need to ensure that the data will be coherent
296                  * with user mappings.
297                  */
298                 __cpuc_flush_dcache_area(ptr, size);
299         }
300         free_safe_buffer(dev->archdata.dmabounce, buf);
301 }
302 
303 /* ************************************************** */
304 
305 /*
306  * see if a buffer address is in an 'unsafe' range.  if it is
307  * allocate a 'safe' buffer and copy the unsafe buffer into it.
308  * substitute the safe buffer for the unsafe one.
309  * (basically move the buffer from an unsafe area to a safe one)
310  */
311 static dma_addr_t dmabounce_map_page(struct device *dev, struct page *page,
312                 unsigned long offset, size_t size, enum dma_data_direction dir,
313                 struct dma_attrs *attrs)
314 {
315         dma_addr_t dma_addr;
316         int ret;
317 
318         dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
319                 __func__, page, offset, size, dir);
320 
321         dma_addr = pfn_to_dma(dev, page_to_pfn(page)) + offset;
322 
323         ret = needs_bounce(dev, dma_addr, size);
324         if (ret < 0)
325                 return DMA_ERROR_CODE;
326 
327         if (ret == 0) {
328                 arm_dma_ops.sync_single_for_device(dev, dma_addr, size, dir);
329                 return dma_addr;
330         }
331 
332         if (PageHighMem(page)) {
333                 dev_err(dev, "DMA buffer bouncing of HIGHMEM pages is not supported\n");
334                 return DMA_ERROR_CODE;
335         }
336 
337         return map_single(dev, page_address(page) + offset, size, dir);
338 }
339 
340 /*
341  * see if a mapped address was really a "safe" buffer and if so, copy
342  * the data from the safe buffer back to the unsafe buffer and free up
343  * the safe buffer.  (basically return things back to the way they
344  * should be)
345  */
346 static void dmabounce_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
347                 enum dma_data_direction dir, struct dma_attrs *attrs)
348 {
349         struct safe_buffer *buf;
350 
351         dev_dbg(dev, "%s(dma=%#x,size=%d,dir=%x)\n",
352                 __func__, dma_addr, size, dir);
353 
354         buf = find_safe_buffer_dev(dev, dma_addr, __func__);
355         if (!buf) {
356                 arm_dma_ops.sync_single_for_cpu(dev, dma_addr, size, dir);
357                 return;
358         }
359 
360         unmap_single(dev, buf, size, dir);
361 }
362 
363 static int __dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
364                 size_t sz, enum dma_data_direction dir)
365 {
366         struct safe_buffer *buf;
367         unsigned long off;
368 
369         dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n",
370                 __func__, addr, sz, dir);
371 
372         buf = find_safe_buffer_dev(dev, addr, __func__);
373         if (!buf)
374                 return 1;
375 
376         off = addr - buf->safe_dma_addr;
377 
378         BUG_ON(buf->direction != dir);
379 
380         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
381                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
382                 buf->safe, buf->safe_dma_addr);
383 
384         DO_STATS(dev->archdata.dmabounce->bounce_count++);
385 
386         if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
387                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
388                         __func__, buf->safe + off, buf->ptr + off, sz);
389                 memcpy(buf->ptr + off, buf->safe + off, sz);
390         }
391         return 0;
392 }
393 
394 static void dmabounce_sync_for_cpu(struct device *dev,
395                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
396 {
397         if (!__dmabounce_sync_for_cpu(dev, handle, size, dir))
398                 return;
399 
400         arm_dma_ops.sync_single_for_cpu(dev, handle, size, dir);
401 }
402 
403 static int __dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
404                 size_t sz, enum dma_data_direction dir)
405 {
406         struct safe_buffer *buf;
407         unsigned long off;
408 
409         dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n",
410                 __func__, addr, sz, dir);
411 
412         buf = find_safe_buffer_dev(dev, addr, __func__);
413         if (!buf)
414                 return 1;
415 
416         off = addr - buf->safe_dma_addr;
417 
418         BUG_ON(buf->direction != dir);
419 
420         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
421                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
422                 buf->safe, buf->safe_dma_addr);
423 
424         DO_STATS(dev->archdata.dmabounce->bounce_count++);
425 
426         if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
427                 dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
428                         __func__,buf->ptr + off, buf->safe + off, sz);
429                 memcpy(buf->safe + off, buf->ptr + off, sz);
430         }
431         return 0;
432 }
433 
434 static void dmabounce_sync_for_device(struct device *dev,
435                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
436 {
437         if (!__dmabounce_sync_for_device(dev, handle, size, dir))
438                 return;
439 
440         arm_dma_ops.sync_single_for_device(dev, handle, size, dir);
441 }
442 
443 static int dmabounce_set_mask(struct device *dev, u64 dma_mask)
444 {
445         if (dev->archdata.dmabounce)
446                 return 0;
447 
448         return arm_dma_ops.set_dma_mask(dev, dma_mask);
449 }
450 
451 static struct dma_map_ops dmabounce_ops = {
452         .alloc                  = arm_dma_alloc,
453         .free                   = arm_dma_free,
454         .mmap                   = arm_dma_mmap,
455         .get_sgtable            = arm_dma_get_sgtable,
456         .map_page               = dmabounce_map_page,
457         .unmap_page             = dmabounce_unmap_page,
458         .sync_single_for_cpu    = dmabounce_sync_for_cpu,
459         .sync_single_for_device = dmabounce_sync_for_device,
460         .map_sg                 = arm_dma_map_sg,
461         .unmap_sg               = arm_dma_unmap_sg,
462         .sync_sg_for_cpu        = arm_dma_sync_sg_for_cpu,
463         .sync_sg_for_device     = arm_dma_sync_sg_for_device,
464         .set_dma_mask           = dmabounce_set_mask,
465 };
466 
467 static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
468                 const char *name, unsigned long size)
469 {
470         pool->size = size;
471         DO_STATS(pool->allocs = 0);
472         pool->pool = dma_pool_create(name, dev, size,
473                                      0 /* byte alignment */,
474                                      0 /* no page-crossing issues */);
475 
476         return pool->pool ? 0 : -ENOMEM;
477 }
478 
479 int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
480                 unsigned long large_buffer_size,
481                 int (*needs_bounce_fn)(struct device *, dma_addr_t, size_t))
482 {
483         struct dmabounce_device_info *device_info;
484         int ret;
485 
486         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
487         if (!device_info) {
488                 dev_err(dev,
489                         "Could not allocated dmabounce_device_info\n");
490                 return -ENOMEM;
491         }
492 
493         ret = dmabounce_init_pool(&device_info->small, dev,
494                                   "small_dmabounce_pool", small_buffer_size);
495         if (ret) {
496                 dev_err(dev,
497                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
498                         small_buffer_size);
499                 goto err_free;
500         }
501 
502         if (large_buffer_size) {
503                 ret = dmabounce_init_pool(&device_info->large, dev,
504                                           "large_dmabounce_pool",
505                                           large_buffer_size);
506                 if (ret) {
507                         dev_err(dev,
508                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
509                                 large_buffer_size);
510                         goto err_destroy;
511                 }
512         }
513 
514         device_info->dev = dev;
515         INIT_LIST_HEAD(&device_info->safe_buffers);
516         rwlock_init(&device_info->lock);
517         device_info->needs_bounce = needs_bounce_fn;
518 
519 #ifdef STATS
520         device_info->total_allocs = 0;
521         device_info->map_op_count = 0;
522         device_info->bounce_count = 0;
523         device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
524 #endif
525 
526         dev->archdata.dmabounce = device_info;
527         set_dma_ops(dev, &dmabounce_ops);
528 
529         dev_info(dev, "dmabounce: registered device\n");
530 
531         return 0;
532 
533  err_destroy:
534         dma_pool_destroy(device_info->small.pool);
535  err_free:
536         kfree(device_info);
537         return ret;
538 }
539 EXPORT_SYMBOL(dmabounce_register_dev);
540 
541 void dmabounce_unregister_dev(struct device *dev)
542 {
543         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
544 
545         dev->archdata.dmabounce = NULL;
546         set_dma_ops(dev, NULL);
547 
548         if (!device_info) {
549                 dev_warn(dev,
550                          "Never registered with dmabounce but attempting"
551                          "to unregister!\n");
552                 return;
553         }
554 
555         if (!list_empty(&device_info->safe_buffers)) {
556                 dev_err(dev,
557                         "Removing from dmabounce with pending buffers!\n");
558                 BUG();
559         }
560 
561         if (device_info->small.pool)
562                 dma_pool_destroy(device_info->small.pool);
563         if (device_info->large.pool)
564                 dma_pool_destroy(device_info->large.pool);
565 
566 #ifdef STATS
567         if (device_info->attr_res == 0)
568                 device_remove_file(dev, &dev_attr_dmabounce_stats);
569 #endif
570 
571         kfree(device_info);
572 
573         dev_info(dev, "dmabounce: device unregistered\n");
574 }
575 EXPORT_SYMBOL(dmabounce_unregister_dev);
576 
577 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
578 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
579 MODULE_LICENSE("GPL");
580 

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