1/*
2 *  linux/arch/arm/mm/dma-mapping.c
3 *
4 *  Copyright (C) 2000-2004 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 *  DMA uncached mapping support.
11 */
12#include <linux/module.h>
13#include <linux/mm.h>
14#include <linux/gfp.h>
15#include <linux/errno.h>
16#include <linux/list.h>
17#include <linux/init.h>
18#include <linux/device.h>
19#include <linux/dma-mapping.h>
20#include <linux/highmem.h>
21#include <linux/slab.h>
22
23#include <asm/memory.h>
24#include <asm/highmem.h>
25#include <asm/cacheflush.h>
26#include <asm/tlbflush.h>
27#include <asm/sizes.h>
28#include <asm/mach/arch.h>
29
30#include "mm.h"
31
32static u64 get_coherent_dma_mask(struct device *dev)
33{
34	u64 mask = (u64)arm_dma_limit;
35
36	if (dev) {
37		mask = dev->coherent_dma_mask;
38
39		/*
40		 * Sanity check the DMA mask - it must be non-zero, and
41		 * must be able to be satisfied by a DMA allocation.
42		 */
43		if (mask == 0) {
44			dev_warn(dev, "coherent DMA mask is unset\n");
45			return 0;
46		}
47
48		if ((~mask) & (u64)arm_dma_limit) {
49			dev_warn(dev, "coherent DMA mask %#llx is smaller "
50				 "than system GFP_DMA mask %#llx\n",
51				 mask, (u64)arm_dma_limit);
52			return 0;
53		}
54	}
55
56	return mask;
57}
58
59/*
60 * Allocate a DMA buffer for 'dev' of size 'size' using the
61 * specified gfp mask.  Note that 'size' must be page aligned.
62 */
63static struct page *__dma_alloc_buffer(struct device *dev, size_t size, gfp_t gfp)
64{
65	unsigned long order = get_order(size);
66	struct page *page, *p, *e;
67	void *ptr;
68	u64 mask = get_coherent_dma_mask(dev);
69
70#ifdef CONFIG_DMA_API_DEBUG
71	u64 limit = (mask + 1) & ~mask;
72	if (limit && size >= limit) {
73		dev_warn(dev, "coherent allocation too big (requested %#x mask %#llx)\n",
74			size, mask);
75		return NULL;
76	}
77#endif
78
79	if (!mask)
80		return NULL;
81
82	if (mask < 0xffffffffULL)
83		gfp |= GFP_DMA;
84
85	page = alloc_pages(gfp, order);
86	if (!page)
87		return NULL;
88
89	/*
90	 * Now split the huge page and free the excess pages
91	 */
92	split_page(page, order);
93	for (p = page + (size >> PAGE_SHIFT), e = page + (1 << order); p < e; p++)
94		__free_page(p);
95
96	/*
97	 * Ensure that the allocated pages are zeroed, and that any data
98	 * lurking in the kernel direct-mapped region is invalidated.
99	 */
100	ptr = page_address(page);
101	memset(ptr, 0, size);
102	dmac_flush_range(ptr, ptr + size);
103	outer_flush_range(__pa(ptr), __pa(ptr) + size);
104
105	return page;
106}
107
108/*
109 * Free a DMA buffer.  'size' must be page aligned.
110 */
111static void __dma_free_buffer(struct page *page, size_t size)
112{
113	struct page *e = page + (size >> PAGE_SHIFT);
114
115	while (page < e) {
116		__free_page(page);
117		page++;
118	}
119}
120
121#ifdef CONFIG_MMU
122
123#define CONSISTENT_OFFSET(x)	(((unsigned long)(x) - consistent_base) >> PAGE_SHIFT)
124#define CONSISTENT_PTE_INDEX(x) (((unsigned long)(x) - consistent_base) >> PMD_SHIFT)
125
126/*
127 * These are the page tables (2MB each) covering uncached, DMA consistent allocations
128 */
129static pte_t **consistent_pte;
130
131#define DEFAULT_CONSISTENT_DMA_SIZE SZ_2M
132
133unsigned long consistent_base = CONSISTENT_END - DEFAULT_CONSISTENT_DMA_SIZE;
134
135void __init init_consistent_dma_size(unsigned long size)
136{
137	unsigned long base = CONSISTENT_END - ALIGN(size, SZ_2M);
138
139	BUG_ON(consistent_pte); /* Check we're called before DMA region init */
140	BUG_ON(base < VMALLOC_END);
141
142	/* Grow region to accommodate specified size  */
143	if (base < consistent_base)
144		consistent_base = base;
145}
146
147#include "vmregion.h"
148
149static struct arm_vmregion_head consistent_head = {
150	.vm_lock	= __SPIN_LOCK_UNLOCKED(&consistent_head.vm_lock),
151	.vm_list	= LIST_HEAD_INIT(consistent_head.vm_list),
152	.vm_end		= CONSISTENT_END,
153};
154
155#ifdef CONFIG_HUGETLB_PAGE
156#error ARM Coherent DMA allocator does not (yet) support huge TLB
157#endif
158
159/*
160 * Initialise the consistent memory allocation.
161 */
162static int __init consistent_init(void)
163{
164	int ret = 0;
165	pgd_t *pgd;
166	pud_t *pud;
167	pmd_t *pmd;
168	pte_t *pte;
169	int i = 0;
170	unsigned long base = consistent_base;
171	unsigned long num_ptes = (CONSISTENT_END - base) >> PMD_SHIFT;
172
173	consistent_pte = kmalloc(num_ptes * sizeof(pte_t), GFP_KERNEL);
174	if (!consistent_pte) {
175		pr_err("%s: no memory\n", __func__);
176		return -ENOMEM;
177	}
178
179	pr_debug("DMA memory: 0x%08lx - 0x%08lx:\n", base, CONSISTENT_END);
180	consistent_head.vm_start = base;
181
182	do {
183		pgd = pgd_offset(&init_mm, base);
184
185		pud = pud_alloc(&init_mm, pgd, base);
186		if (!pud) {
187			printk(KERN_ERR "%s: no pud tables\n", __func__);
188			ret = -ENOMEM;
189			break;
190		}
191
192		pmd = pmd_alloc(&init_mm, pud, base);
193		if (!pmd) {
194			printk(KERN_ERR "%s: no pmd tables\n", __func__);
195			ret = -ENOMEM;
196			break;
197		}
198		WARN_ON(!pmd_none(*pmd));
199
200		pte = pte_alloc_kernel(pmd, base);
201		if (!pte) {
202			printk(KERN_ERR "%s: no pte tables\n", __func__);
203			ret = -ENOMEM;
204			break;
205		}
206
207		consistent_pte[i++] = pte;
208		base += PMD_SIZE;
209	} while (base < CONSISTENT_END);
210
211	return ret;
212}
213
214core_initcall(consistent_init);
215
216static void *
217__dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot,
218	const void *caller)
219{
220	struct arm_vmregion *c;
221	size_t align;
222	int bit;
223
224	if (!consistent_pte) {
225		printk(KERN_ERR "%s: not initialised\n", __func__);
226		dump_stack();
227		return NULL;
228	}
229
230	/*
231	 * Align the virtual region allocation - maximum alignment is
232	 * a section size, minimum is a page size.  This helps reduce
233	 * fragmentation of the DMA space, and also prevents allocations
234	 * smaller than a section from crossing a section boundary.
235	 */
236	bit = fls(size - 1);
237	if (bit > SECTION_SHIFT)
238		bit = SECTION_SHIFT;
239	align = 1 << bit;
240
241	/*
242	 * Allocate a virtual address in the consistent mapping region.
243	 */
244	c = arm_vmregion_alloc(&consistent_head, align, size,
245			    gfp & ~(__GFP_DMA | __GFP_HIGHMEM), caller);
246	if (c) {
247		pte_t *pte;
248		int idx = CONSISTENT_PTE_INDEX(c->vm_start);
249		u32 off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
250
251		pte = consistent_pte[idx] + off;
252		c->vm_pages = page;
253
254		do {
255			BUG_ON(!pte_none(*pte));
256
257			set_pte_ext(pte, mk_pte(page, prot), 0);
258			page++;
259			pte++;
260			off++;
261			if (off >= PTRS_PER_PTE) {
262				off = 0;
263				pte = consistent_pte[++idx];
264			}
265		} while (size -= PAGE_SIZE);
266
267		dsb();
268
269		return (void *)c->vm_start;
270	}
271	return NULL;
272}
273
274static void __dma_free_remap(void *cpu_addr, size_t size)
275{
276	struct arm_vmregion *c;
277	unsigned long addr;
278	pte_t *ptep;
279	int idx;
280	u32 off;
281
282	c = arm_vmregion_find_remove(&consistent_head, (unsigned long)cpu_addr);
283	if (!c) {
284		printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
285		       __func__, cpu_addr);
286		dump_stack();
287		return;
288	}
289
290	if ((c->vm_end - c->vm_start) != size) {
291		printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
292		       __func__, c->vm_end - c->vm_start, size);
293		dump_stack();
294		size = c->vm_end - c->vm_start;
295	}
296
297	idx = CONSISTENT_PTE_INDEX(c->vm_start);
298	off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
299	ptep = consistent_pte[idx] + off;
300	addr = c->vm_start;
301	do {
302		pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
303
304		ptep++;
305		addr += PAGE_SIZE;
306		off++;
307		if (off >= PTRS_PER_PTE) {
308			off = 0;
309			ptep = consistent_pte[++idx];
310		}
311
312		if (pte_none(pte) || !pte_present(pte))
313			printk(KERN_CRIT "%s: bad page in kernel page table\n",
314			       __func__);
315	} while (size -= PAGE_SIZE);
316
317	flush_tlb_kernel_range(c->vm_start, c->vm_end);
318
319	arm_vmregion_free(&consistent_head, c);
320}
321
322#else	/* !CONFIG_MMU */
323
324#define __dma_alloc_remap(page, size, gfp, prot, c)	page_address(page)
325#define __dma_free_remap(addr, size)			do { } while (0)
326
327#endif	/* CONFIG_MMU */
328
329static void *
330__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
331	    pgprot_t prot, const void *caller)
332{
333	struct page *page;
334	void *addr;
335
336	/*
337	 * Following is a work-around (a.k.a. hack) to prevent pages
338	 * with __GFP_COMP being passed to split_page() which cannot
339	 * handle them.  The real problem is that this flag probably
340	 * should be 0 on ARM as it is not supported on this
341	 * platform; see CONFIG_HUGETLBFS.
342	 */
343	gfp &= ~(__GFP_COMP);
344
345	*handle = ~0;
346	size = PAGE_ALIGN(size);
347
348	page = __dma_alloc_buffer(dev, size, gfp);
349	if (!page)
350		return NULL;
351
352	if (!arch_is_coherent())
353		addr = __dma_alloc_remap(page, size, gfp, prot, caller);
354	else
355		addr = page_address(page);
356
357	if (addr)
358		*handle = pfn_to_dma(dev, page_to_pfn(page));
359	else
360		__dma_free_buffer(page, size);
361
362	return addr;
363}
364
365/*
366 * Allocate DMA-coherent memory space and return both the kernel remapped
367 * virtual and bus address for that space.
368 */
369void *
370dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
371{
372	void *memory;
373
374	if (dma_alloc_from_coherent(dev, size, handle, &memory))
375		return memory;
376
377	return __dma_alloc(dev, size, handle, gfp,
378			   pgprot_dmacoherent(pgprot_kernel),
379			   __builtin_return_address(0));
380}
381EXPORT_SYMBOL(dma_alloc_coherent);
382
383/*
384 * Allocate a writecombining region, in much the same way as
385 * dma_alloc_coherent above.
386 */
387void *
388dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
389{
390	return __dma_alloc(dev, size, handle, gfp,
391			   pgprot_writecombine(pgprot_kernel),
392			   __builtin_return_address(0));
393}
394EXPORT_SYMBOL(dma_alloc_writecombine);
395
396static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
397		    void *cpu_addr, dma_addr_t dma_addr, size_t size)
398{
399	int ret = -ENXIO;
400#ifdef CONFIG_MMU
401	unsigned long user_size, kern_size;
402	struct arm_vmregion *c;
403
404	user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
405
406	c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr);
407	if (c) {
408		unsigned long off = vma->vm_pgoff;
409
410		kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT;
411
412		if (off < kern_size &&
413		    user_size <= (kern_size - off)) {
414			ret = remap_pfn_range(vma, vma->vm_start,
415					      page_to_pfn(c->vm_pages) + off,
416					      user_size << PAGE_SHIFT,
417					      vma->vm_page_prot);
418		}
419	}
420#endif	/* CONFIG_MMU */
421
422	return ret;
423}
424
425int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
426		      void *cpu_addr, dma_addr_t dma_addr, size_t size)
427{
428	vma->vm_page_prot = pgprot_dmacoherent(vma->vm_page_prot);
429	return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
430}
431EXPORT_SYMBOL(dma_mmap_coherent);
432
433int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
434			  void *cpu_addr, dma_addr_t dma_addr, size_t size)
435{
436	vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
437	return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
438}
439EXPORT_SYMBOL(dma_mmap_writecombine);
440
441/*
442 * free a page as defined by the above mapping.
443 * Must not be called with IRQs disabled.
444 */
445void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
446{
447	WARN_ON(irqs_disabled());
448
449	if (dma_release_from_coherent(dev, get_order(size), cpu_addr))
450		return;
451
452	size = PAGE_ALIGN(size);
453
454	if (!arch_is_coherent())
455		__dma_free_remap(cpu_addr, size);
456
457	__dma_free_buffer(pfn_to_page(dma_to_pfn(dev, handle)), size);
458}
459EXPORT_SYMBOL(dma_free_coherent);
460
461/*
462 * Make an area consistent for devices.
463 * Note: Drivers should NOT use this function directly, as it will break
464 * platforms with CONFIG_DMABOUNCE.
465 * Use the driver DMA support - see dma-mapping.h (dma_sync_*)
466 */
467void ___dma_single_cpu_to_dev(const void *kaddr, size_t size,
468	enum dma_data_direction dir)
469{
470	unsigned long paddr;
471
472	BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size - 1));
473
474	dmac_map_area(kaddr, size, dir);
475
476	paddr = __pa(kaddr);
477	if (dir == DMA_FROM_DEVICE) {
478		outer_inv_range(paddr, paddr + size);
479	} else {
480		outer_clean_range(paddr, paddr + size);
481	}
482	/* FIXME: non-speculating: flush on bidirectional mappings? */
483}
484EXPORT_SYMBOL(___dma_single_cpu_to_dev);
485
486void ___dma_single_dev_to_cpu(const void *kaddr, size_t size,
487	enum dma_data_direction dir)
488{
489	BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size - 1));
490
491	/* FIXME: non-speculating: not required */
492	/* don't bother invalidating if DMA to device */
493	if (dir != DMA_TO_DEVICE) {
494		unsigned long paddr = __pa(kaddr);
495		outer_inv_range(paddr, paddr + size);
496	}
497
498	dmac_unmap_area(kaddr, size, dir);
499}
500EXPORT_SYMBOL(___dma_single_dev_to_cpu);
501
502static void dma_cache_maint_page(struct page *page, unsigned long offset,
503	size_t size, enum dma_data_direction dir,
504	void (*op)(const void *, size_t, int))
505{
506	/*
507	 * A single sg entry may refer to multiple physically contiguous
508	 * pages.  But we still need to process highmem pages individually.
509	 * If highmem is not configured then the bulk of this loop gets
510	 * optimized out.
511	 */
512	size_t left = size;
513	do {
514		size_t len = left;
515		void *vaddr;
516
517		if (PageHighMem(page)) {
518			if (len + offset > PAGE_SIZE) {
519				if (offset >= PAGE_SIZE) {
520					page += offset / PAGE_SIZE;
521					offset %= PAGE_SIZE;
522				}
523				len = PAGE_SIZE - offset;
524			}
525			vaddr = kmap_high_get(page);
526			if (vaddr) {
527				vaddr += offset;
528				op(vaddr, len, dir);
529				kunmap_high(page);
530			} else if (cache_is_vipt()) {
531				/* unmapped pages might still be cached */
532				vaddr = kmap_atomic(page);
533				op(vaddr + offset, len, dir);
534				kunmap_atomic(vaddr);
535			}
536		} else {
537			vaddr = page_address(page) + offset;
538			op(vaddr, len, dir);
539		}
540		offset = 0;
541		page++;
542		left -= len;
543	} while (left);
544}
545
546void ___dma_page_cpu_to_dev(struct page *page, unsigned long off,
547	size_t size, enum dma_data_direction dir)
548{
549	unsigned long paddr;
550
551	dma_cache_maint_page(page, off, size, dir, dmac_map_area);
552
553	paddr = page_to_phys(page) + off;
554	if (dir == DMA_FROM_DEVICE) {
555		outer_inv_range(paddr, paddr + size);
556	} else {
557		outer_clean_range(paddr, paddr + size);
558	}
559	/* FIXME: non-speculating: flush on bidirectional mappings? */
560}
561EXPORT_SYMBOL(___dma_page_cpu_to_dev);
562
563void ___dma_page_dev_to_cpu(struct page *page, unsigned long off,
564	size_t size, enum dma_data_direction dir)
565{
566	unsigned long paddr = page_to_phys(page) + off;
567
568	/* FIXME: non-speculating: not required */
569	/* don't bother invalidating if DMA to device */
570	if (dir != DMA_TO_DEVICE)
571		outer_inv_range(paddr, paddr + size);
572
573	dma_cache_maint_page(page, off, size, dir, dmac_unmap_area);
574
575	/*
576	 * Mark the D-cache clean for this page to avoid extra flushing.
577	 */
578	if (dir != DMA_TO_DEVICE && off == 0 && size >= PAGE_SIZE)
579		set_bit(PG_dcache_clean, &page->flags);
580}
581EXPORT_SYMBOL(___dma_page_dev_to_cpu);
582
583/**
584 * dma_map_sg - map a set of SG buffers for streaming mode DMA
585 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
586 * @sg: list of buffers
587 * @nents: number of buffers to map
588 * @dir: DMA transfer direction
589 *
590 * Map a set of buffers described by scatterlist in streaming mode for DMA.
591 * This is the scatter-gather version of the dma_map_single interface.
592 * Here the scatter gather list elements are each tagged with the
593 * appropriate dma address and length.  They are obtained via
594 * sg_dma_{address,length}.
595 *
596 * Device ownership issues as mentioned for dma_map_single are the same
597 * here.
598 */
599int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
600		enum dma_data_direction dir)
601{
602	struct scatterlist *s;
603	int i, j;
604
605	BUG_ON(!valid_dma_direction(dir));
606
607	for_each_sg(sg, s, nents, i) {
608		s->dma_address = __dma_map_page(dev, sg_page(s), s->offset,
609						s->length, dir);
610		if (dma_mapping_error(dev, s->dma_address))
611			goto bad_mapping;
612	}
613	debug_dma_map_sg(dev, sg, nents, nents, dir);
614	return nents;
615
616 bad_mapping:
617	for_each_sg(sg, s, i, j)
618		__dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir);
619	return 0;
620}
621EXPORT_SYMBOL(dma_map_sg);
622
623/**
624 * dma_unmap_sg - unmap a set of SG buffers mapped by dma_map_sg
625 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
626 * @sg: list of buffers
627 * @nents: number of buffers to unmap (same as was passed to dma_map_sg)
628 * @dir: DMA transfer direction (same as was passed to dma_map_sg)
629 *
630 * Unmap a set of streaming mode DMA translations.  Again, CPU access
631 * rules concerning calls here are the same as for dma_unmap_single().
632 */
633void dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
634		enum dma_data_direction dir)
635{
636	struct scatterlist *s;
637	int i;
638
639	debug_dma_unmap_sg(dev, sg, nents, dir);
640
641	for_each_sg(sg, s, nents, i)
642		__dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir);
643}
644EXPORT_SYMBOL(dma_unmap_sg);
645
646/**
647 * dma_sync_sg_for_cpu
648 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
649 * @sg: list of buffers
650 * @nents: number of buffers to map (returned from dma_map_sg)
651 * @dir: DMA transfer direction (same as was passed to dma_map_sg)
652 */
653void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
654			int nents, enum dma_data_direction dir)
655{
656	struct scatterlist *s;
657	int i;
658
659	for_each_sg(sg, s, nents, i) {
660		if (!dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0,
661					    sg_dma_len(s), dir))
662			continue;
663
664		__dma_page_dev_to_cpu(sg_page(s), s->offset,
665				      s->length, dir);
666	}
667
668	debug_dma_sync_sg_for_cpu(dev, sg, nents, dir);
669}
670EXPORT_SYMBOL(dma_sync_sg_for_cpu);
671
672/**
673 * dma_sync_sg_for_device
674 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
675 * @sg: list of buffers
676 * @nents: number of buffers to map (returned from dma_map_sg)
677 * @dir: DMA transfer direction (same as was passed to dma_map_sg)
678 */
679void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
680			int nents, enum dma_data_direction dir)
681{
682	struct scatterlist *s;
683	int i;
684
685	for_each_sg(sg, s, nents, i) {
686		if (!dmabounce_sync_for_device(dev, sg_dma_address(s), 0,
687					sg_dma_len(s), dir))
688			continue;
689
690		__dma_page_cpu_to_dev(sg_page(s), s->offset,
691				      s->length, dir);
692	}
693
694	debug_dma_sync_sg_for_device(dev, sg, nents, dir);
695}
696EXPORT_SYMBOL(dma_sync_sg_for_device);
697
698/*
699 * Return whether the given device DMA address mask can be supported
700 * properly.  For example, if your device can only drive the low 24-bits
701 * during bus mastering, then you would pass 0x00ffffff as the mask
702 * to this function.
703 */
704int dma_supported(struct device *dev, u64 mask)
705{
706	if (mask < (u64)arm_dma_limit)
707		return 0;
708	return 1;
709}
710EXPORT_SYMBOL(dma_supported);
711
712int dma_set_mask(struct device *dev, u64 dma_mask)
713{
714	if (!dev->dma_mask || !dma_supported(dev, dma_mask))
715		return -EIO;
716
717#ifndef CONFIG_DMABOUNCE
718	*dev->dma_mask = dma_mask;
719#endif
720
721	return 0;
722}
723EXPORT_SYMBOL(dma_set_mask);
724
725#define PREALLOC_DMA_DEBUG_ENTRIES	4096
726
727static int __init dma_debug_do_init(void)
728{
729#ifdef CONFIG_MMU
730	arm_vmregion_create_proc("dma-mappings", &consistent_head);
731#endif
732	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
733	return 0;
734}
735fs_initcall(dma_debug_do_init);
736