Root/arch/arm/common/dmabounce.c

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
47struct 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
61struct dmabounce_pool {
62    unsigned long size;
63    struct dma_pool *pool;
64#ifdef STATS
65    unsigned long allocs;
66#endif
67};
68
69struct 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
85static 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
99static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL);
100#endif
101
102
103/* allocate a 'safe' buffer and keep track of it */
104static inline struct safe_buffer *
105alloc_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 */
165static inline struct safe_buffer *
166find_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
183static inline void
184free_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
207static 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
222static 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_single_cpu_to_dev(ptr, size, dir);
281    }
282
283    return dma_addr;
284}
285
286static 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             * Since we may have written to a page cache page,
312             * we need to ensure that the data will be coherent
313             * with user mappings.
314             */
315            __cpuc_flush_dcache_area(ptr, size);
316        }
317        free_safe_buffer(dev->archdata.dmabounce, buf);
318    } else {
319        __dma_single_dev_to_cpu(dma_to_virt(dev, dma_addr), size, dir);
320    }
321}
322
323/* ************************************************** */
324
325/*
326 * see if a buffer address is in an 'unsafe' range. if it is
327 * allocate a 'safe' buffer and copy the unsafe buffer into it.
328 * substitute the safe buffer for the unsafe one.
329 * (basically move the buffer from an unsafe area to a safe one)
330 */
331dma_addr_t dma_map_single(struct device *dev, void *ptr, size_t size,
332        enum dma_data_direction dir)
333{
334    dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
335        __func__, ptr, size, dir);
336
337    BUG_ON(!valid_dma_direction(dir));
338
339    return map_single(dev, ptr, size, dir);
340}
341EXPORT_SYMBOL(dma_map_single);
342
343/*
344 * see if a mapped address was really a "safe" buffer and if so, copy
345 * the data from the safe buffer back to the unsafe buffer and free up
346 * the safe buffer. (basically return things back to the way they
347 * should be)
348 */
349void dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
350        enum dma_data_direction dir)
351{
352    dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
353        __func__, (void *) dma_addr, size, dir);
354
355    unmap_single(dev, dma_addr, size, dir);
356}
357EXPORT_SYMBOL(dma_unmap_single);
358
359dma_addr_t dma_map_page(struct device *dev, struct page *page,
360        unsigned long offset, size_t size, enum dma_data_direction dir)
361{
362    dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
363        __func__, page, offset, size, dir);
364
365    BUG_ON(!valid_dma_direction(dir));
366
367    if (PageHighMem(page)) {
368        dev_err(dev, "DMA buffer bouncing of HIGHMEM pages "
369                 "is not supported\n");
370        return ~0;
371    }
372
373    return map_single(dev, page_address(page) + offset, size, dir);
374}
375EXPORT_SYMBOL(dma_map_page);
376
377/*
378 * see if a mapped address was really a "safe" buffer and if so, copy
379 * the data from the safe buffer back to the unsafe buffer and free up
380 * the safe buffer. (basically return things back to the way they
381 * should be)
382 */
383void dma_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
384        enum dma_data_direction dir)
385{
386    dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
387        __func__, (void *) dma_addr, size, dir);
388
389    unmap_single(dev, dma_addr, size, dir);
390}
391EXPORT_SYMBOL(dma_unmap_page);
392
393int dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
394        unsigned long off, size_t sz, enum dma_data_direction dir)
395{
396    struct safe_buffer *buf;
397
398    dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
399        __func__, addr, off, sz, dir);
400
401    buf = find_safe_buffer_dev(dev, addr, __func__);
402    if (!buf)
403        return 1;
404
405    BUG_ON(buf->direction != dir);
406
407    dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
408        __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
409        buf->safe, buf->safe_dma_addr);
410
411    DO_STATS(dev->archdata.dmabounce->bounce_count++);
412
413    if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
414        dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
415            __func__, buf->safe + off, buf->ptr + off, sz);
416        memcpy(buf->ptr + off, buf->safe + off, sz);
417    }
418    return 0;
419}
420EXPORT_SYMBOL(dmabounce_sync_for_cpu);
421
422int dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
423        unsigned long off, size_t sz, enum dma_data_direction dir)
424{
425    struct safe_buffer *buf;
426
427    dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
428        __func__, addr, off, sz, dir);
429
430    buf = find_safe_buffer_dev(dev, addr, __func__);
431    if (!buf)
432        return 1;
433
434    BUG_ON(buf->direction != dir);
435
436    dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
437        __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
438        buf->safe, buf->safe_dma_addr);
439
440    DO_STATS(dev->archdata.dmabounce->bounce_count++);
441
442    if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
443        dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
444            __func__,buf->ptr + off, buf->safe + off, sz);
445        memcpy(buf->safe + off, buf->ptr + off, sz);
446    }
447    return 0;
448}
449EXPORT_SYMBOL(dmabounce_sync_for_device);
450
451static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
452        const char *name, unsigned long size)
453{
454    pool->size = size;
455    DO_STATS(pool->allocs = 0);
456    pool->pool = dma_pool_create(name, dev, size,
457                     0 /* byte alignment */,
458                     0 /* no page-crossing issues */);
459
460    return pool->pool ? 0 : -ENOMEM;
461}
462
463int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
464        unsigned long large_buffer_size)
465{
466    struct dmabounce_device_info *device_info;
467    int ret;
468
469    device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
470    if (!device_info) {
471        dev_err(dev,
472            "Could not allocated dmabounce_device_info\n");
473        return -ENOMEM;
474    }
475
476    ret = dmabounce_init_pool(&device_info->small, dev,
477                  "small_dmabounce_pool", small_buffer_size);
478    if (ret) {
479        dev_err(dev,
480            "dmabounce: could not allocate DMA pool for %ld byte objects\n",
481            small_buffer_size);
482        goto err_free;
483    }
484
485    if (large_buffer_size) {
486        ret = dmabounce_init_pool(&device_info->large, dev,
487                      "large_dmabounce_pool",
488                      large_buffer_size);
489        if (ret) {
490            dev_err(dev,
491                "dmabounce: could not allocate DMA pool for %ld byte objects\n",
492                large_buffer_size);
493            goto err_destroy;
494        }
495    }
496
497    device_info->dev = dev;
498    INIT_LIST_HEAD(&device_info->safe_buffers);
499    rwlock_init(&device_info->lock);
500
501#ifdef STATS
502    device_info->total_allocs = 0;
503    device_info->map_op_count = 0;
504    device_info->bounce_count = 0;
505    device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
506#endif
507
508    dev->archdata.dmabounce = device_info;
509
510    dev_info(dev, "dmabounce: registered device\n");
511
512    return 0;
513
514 err_destroy:
515    dma_pool_destroy(device_info->small.pool);
516 err_free:
517    kfree(device_info);
518    return ret;
519}
520EXPORT_SYMBOL(dmabounce_register_dev);
521
522void dmabounce_unregister_dev(struct device *dev)
523{
524    struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
525
526    dev->archdata.dmabounce = NULL;
527
528    if (!device_info) {
529        dev_warn(dev,
530             "Never registered with dmabounce but attempting"
531             "to unregister!\n");
532        return;
533    }
534
535    if (!list_empty(&device_info->safe_buffers)) {
536        dev_err(dev,
537            "Removing from dmabounce with pending buffers!\n");
538        BUG();
539    }
540
541    if (device_info->small.pool)
542        dma_pool_destroy(device_info->small.pool);
543    if (device_info->large.pool)
544        dma_pool_destroy(device_info->large.pool);
545
546#ifdef STATS
547    if (device_info->attr_res == 0)
548        device_remove_file(dev, &dev_attr_dmabounce_stats);
549#endif
550
551    kfree(device_info);
552
553    dev_info(dev, "dmabounce: device unregistered\n");
554}
555EXPORT_SYMBOL(dmabounce_unregister_dev);
556
557MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
558MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
559MODULE_LICENSE("GPL");
560

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