2 * arch/arm/common/dmabounce.c
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.
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>
17 * Copyright (C) 2002 Hewlett Packard Company.
18 * Copyright (C) 2004 MontaVista Software, Inc.
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.
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>
35 #include <asm/cacheflush.h>
40 #define DO_STATS(X) do { X ; } while (0)
42 #define DO_STATS(X) do { } while (0)
45 /* ************************************************** */
48 struct list_head node;
50 /* original request */
55 /* safe buffer info */
56 struct dmabounce_pool *pool;
58 dma_addr_t safe_dma_addr;
61 struct dmabounce_pool {
63 struct dma_pool *pool;
69 struct dmabounce_device_info {
71 struct list_head safe_buffers;
73 unsigned long total_allocs;
74 unsigned long map_op_count;
75 unsigned long bounce_count;
78 struct dmabounce_pool small;
79 struct dmabounce_pool large;
85 static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr,
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);
99 static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL);
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)
108 struct safe_buffer *buf;
109 struct dmabounce_pool *pool;
110 struct device *dev = device_info->dev;
113 dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
114 __func__, ptr, size, dir);
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;
124 buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
126 dev_warn(dev, "%s: kmalloc failed\n", __func__);
132 buf->direction = dir;
136 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC,
137 &buf->safe_dma_addr);
139 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr,
143 if (buf->safe == NULL) {
145 "%s: could not alloc dma memory (size=%d)\n",
154 device_info->total_allocs++;
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);
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)
168 struct safe_buffer *b, *rb = NULL;
171 read_lock_irqsave(&device_info->lock, flags);
173 list_for_each_entry(b, &device_info->safe_buffers, node)
174 if (b->safe_dma_addr == safe_dma_addr) {
179 read_unlock_irqrestore(&device_info->lock, flags);
184 free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
188 dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
190 write_lock_irqsave(&device_info->lock, flags);
192 list_del(&buf->node);
194 write_unlock_irqrestore(&device_info->lock, flags);
197 dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr);
199 dma_free_coherent(device_info->dev, buf->size, buf->safe,
205 /* ************************************************** */
207 static struct safe_buffer *find_safe_buffer_dev(struct device *dev,
208 dma_addr_t dma_addr, const char *where)
210 if (!dev || !dev->archdata.dmabounce)
212 if (dma_mapping_error(dev, dma_addr)) {
213 dev_err(dev, "Trying to %s invalid mapping\n", where);
216 return find_safe_buffer(dev->archdata.dmabounce, dma_addr);
219 static int needs_bounce(struct device *dev, dma_addr_t dma_addr, size_t size)
221 if (!dev || !dev->archdata.dmabounce)
225 unsigned long limit, mask = *dev->dma_mask;
227 limit = (mask + 1) & ~mask;
228 if (limit && size > limit) {
229 dev_err(dev, "DMA mapping too big (requested %#x "
230 "mask %#Lx)\n", size, *dev->dma_mask);
234 /* Figure out if we need to bounce from the DMA mask. */
235 if ((dma_addr | (dma_addr + size - 1)) & ~mask)
239 return dma_needs_bounce(dev, dma_addr, size) ? 1 : 0;
242 static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
243 enum dma_data_direction dir)
245 struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
246 struct safe_buffer *buf;
249 DO_STATS ( device_info->map_op_count++ );
251 buf = alloc_safe_buffer(device_info, ptr, size, dir);
253 dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
258 dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
259 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
260 buf->safe, buf->safe_dma_addr);
262 if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
263 dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
264 __func__, ptr, buf->safe, size);
265 memcpy(buf->safe, ptr, size);
268 return buf->safe_dma_addr;
271 static inline void unmap_single(struct device *dev, struct safe_buffer *buf,
272 size_t size, enum dma_data_direction dir)
274 BUG_ON(buf->size != size);
275 BUG_ON(buf->direction != dir);
277 dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
278 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
279 buf->safe, buf->safe_dma_addr);
281 DO_STATS(dev->archdata.dmabounce->bounce_count++);
283 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
284 void *ptr = buf->ptr;
286 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
287 __func__, buf->safe, ptr, size);
288 memcpy(ptr, buf->safe, size);
291 * Since we may have written to a page cache page,
292 * we need to ensure that the data will be coherent
293 * with user mappings.
295 __cpuc_flush_dcache_area(ptr, size);
297 free_safe_buffer(dev->archdata.dmabounce, buf);
300 /* ************************************************** */
303 * see if a buffer address is in an 'unsafe' range. if it is
304 * allocate a 'safe' buffer and copy the unsafe buffer into it.
305 * substitute the safe buffer for the unsafe one.
306 * (basically move the buffer from an unsafe area to a safe one)
308 dma_addr_t __dma_map_page(struct device *dev, struct page *page,
309 unsigned long offset, size_t size, enum dma_data_direction dir)
314 dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
315 __func__, page, offset, size, dir);
317 dma_addr = pfn_to_dma(dev, page_to_pfn(page)) + offset;
319 ret = needs_bounce(dev, dma_addr, size);
324 __dma_page_cpu_to_dev(page, offset, size, dir);
328 if (PageHighMem(page)) {
329 dev_err(dev, "DMA buffer bouncing of HIGHMEM pages is not supported\n");
333 return map_single(dev, page_address(page) + offset, size, dir);
335 EXPORT_SYMBOL(__dma_map_page);
338 * see if a mapped address was really a "safe" buffer and if so, copy
339 * the data from the safe buffer back to the unsafe buffer and free up
340 * the safe buffer. (basically return things back to the way they
343 void __dma_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
344 enum dma_data_direction dir)
346 struct safe_buffer *buf;
348 dev_dbg(dev, "%s(dma=%#x,size=%d,dir=%x)\n",
349 __func__, dma_addr, size, dir);
351 buf = find_safe_buffer_dev(dev, dma_addr, __func__);
353 __dma_page_dev_to_cpu(pfn_to_page(dma_to_pfn(dev, dma_addr)),
354 dma_addr & ~PAGE_MASK, size, dir);
358 unmap_single(dev, buf, size, dir);
360 EXPORT_SYMBOL(__dma_unmap_page);
362 int dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
363 unsigned long off, size_t sz, enum dma_data_direction dir)
365 struct safe_buffer *buf;
367 dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
368 __func__, addr, off, sz, dir);
370 buf = find_safe_buffer_dev(dev, addr, __func__);
374 BUG_ON(buf->direction != dir);
376 dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
377 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
378 buf->safe, buf->safe_dma_addr);
380 DO_STATS(dev->archdata.dmabounce->bounce_count++);
382 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
383 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
384 __func__, buf->safe + off, buf->ptr + off, sz);
385 memcpy(buf->ptr + off, buf->safe + off, sz);
389 EXPORT_SYMBOL(dmabounce_sync_for_cpu);
391 int dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
392 unsigned long off, size_t sz, enum dma_data_direction dir)
394 struct safe_buffer *buf;
396 dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
397 __func__, addr, off, sz, dir);
399 buf = find_safe_buffer_dev(dev, addr, __func__);
403 BUG_ON(buf->direction != dir);
405 dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
406 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
407 buf->safe, buf->safe_dma_addr);
409 DO_STATS(dev->archdata.dmabounce->bounce_count++);
411 if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
412 dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
413 __func__,buf->ptr + off, buf->safe + off, sz);
414 memcpy(buf->safe + off, buf->ptr + off, sz);
418 EXPORT_SYMBOL(dmabounce_sync_for_device);
420 static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
421 const char *name, unsigned long size)
424 DO_STATS(pool->allocs = 0);
425 pool->pool = dma_pool_create(name, dev, size,
426 0 /* byte alignment */,
427 0 /* no page-crossing issues */);
429 return pool->pool ? 0 : -ENOMEM;
432 int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
433 unsigned long large_buffer_size)
435 struct dmabounce_device_info *device_info;
438 device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
441 "Could not allocated dmabounce_device_info\n");
445 ret = dmabounce_init_pool(&device_info->small, dev,
446 "small_dmabounce_pool", small_buffer_size);
449 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
454 if (large_buffer_size) {
455 ret = dmabounce_init_pool(&device_info->large, dev,
456 "large_dmabounce_pool",
460 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
466 device_info->dev = dev;
467 INIT_LIST_HEAD(&device_info->safe_buffers);
468 rwlock_init(&device_info->lock);
471 device_info->total_allocs = 0;
472 device_info->map_op_count = 0;
473 device_info->bounce_count = 0;
474 device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
477 dev->archdata.dmabounce = device_info;
479 dev_info(dev, "dmabounce: registered device\n");
484 dma_pool_destroy(device_info->small.pool);
489 EXPORT_SYMBOL(dmabounce_register_dev);
491 void dmabounce_unregister_dev(struct device *dev)
493 struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
495 dev->archdata.dmabounce = NULL;
499 "Never registered with dmabounce but attempting"
504 if (!list_empty(&device_info->safe_buffers)) {
506 "Removing from dmabounce with pending buffers!\n");
510 if (device_info->small.pool)
511 dma_pool_destroy(device_info->small.pool);
512 if (device_info->large.pool)
513 dma_pool_destroy(device_info->large.pool);
516 if (device_info->attr_res == 0)
517 device_remove_file(dev, &dev_attr_dmabounce_stats);
522 dev_info(dev, "dmabounce: device unregistered\n");
524 EXPORT_SYMBOL(dmabounce_unregister_dev);
526 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
527 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
528 MODULE_LICENSE("GPL");