[deliverable/linux.git] / arch / arm / mm / consistent.c

/*
 *  linux/arch/arm/mm/consistent.c
 *
 *  Copyright (C) 2000-2004 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  DMA uncached mapping support.
 */
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>

#include <asm/cacheflush.h>
#include <asm/io.h>
#include <asm/tlbflush.h>

#define CONSISTENT_BASE	(0xffc00000)
#define CONSISTENT_END	(0xffe00000)
#define CONSISTENT_OFFSET(x)	(((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)

/*
 * This is the page table (2MB) covering uncached, DMA consistent allocations
 */
static pte_t *consistent_pte;
static DEFINE_SPINLOCK(consistent_lock);

/*
 * VM region handling support.
 *
 * This should become something generic, handling VM region allocations for
 * vmalloc and similar (ioremap, module space, etc).
 *
 * I envisage vmalloc()'s supporting vm_struct becoming:
 *
 *  struct vm_struct {
 *    struct vm_region	region;
 *    unsigned long	flags;
 *    struct page	**pages;
 *    unsigned int	nr_pages;
 *    unsigned long	phys_addr;
 *  };
 *
 * get_vm_area() would then call vm_region_alloc with an appropriate
 * struct vm_region head (eg):
 *
 *  struct vm_region vmalloc_head = {
 *	.vm_list	= LIST_HEAD_INIT(vmalloc_head.vm_list),
 *	.vm_start	= VMALLOC_START,
 *	.vm_end		= VMALLOC_END,
 *  };
 *
 * However, vmalloc_head.vm_start is variable (typically, it is dependent on
 * the amount of RAM found at boot time.)  I would imagine that get_vm_area()
 * would have to initialise this each time prior to calling vm_region_alloc().
 */
struct vm_region {
	struct list_head	vm_list;
	unsigned long		vm_start;
	unsigned long		vm_end;
	struct page		*vm_pages;
	int			vm_active;
};

static struct vm_region consistent_head = {
	.vm_list	= LIST_HEAD_INIT(consistent_head.vm_list),
	.vm_start	= CONSISTENT_BASE,
	.vm_end		= CONSISTENT_END,
};

static struct vm_region *
vm_region_alloc(struct vm_region *head, size_t size, gfp_t gfp)
{
	unsigned long addr = head->vm_start, end = head->vm_end - size;
	unsigned long flags;
	struct vm_region *c, *new;

	new = kmalloc(sizeof(struct vm_region), gfp);
	if (!new)
		goto out;

	spin_lock_irqsave(&consistent_lock, flags);

	list_for_each_entry(c, &head->vm_list, vm_list) {
		if ((addr + size) < addr)
			goto nospc;
		if ((addr + size) <= c->vm_start)
			goto found;
		addr = c->vm_end;
		if (addr > end)
			goto nospc;
	}

 found:
	/*
	 * Insert this entry _before_ the one we found.
	 */
	list_add_tail(&new->vm_list, &c->vm_list);
	new->vm_start = addr;
	new->vm_end = addr + size;
	new->vm_active = 1;

	spin_unlock_irqrestore(&consistent_lock, flags);
	return new;

 nospc:
	spin_unlock_irqrestore(&consistent_lock, flags);
	kfree(new);
 out:
	return NULL;
}

static struct vm_region *vm_region_find(struct vm_region *head, unsigned long addr)
{
	struct vm_region *c;
	
	list_for_each_entry(c, &head->vm_list, vm_list) {
		if (c->vm_active && c->vm_start == addr)
			goto out;
	}
	c = NULL;
 out:
	return c;
}

#ifdef CONFIG_HUGETLB_PAGE
#error ARM Coherent DMA allocator does not (yet) support huge TLB
#endif

static void *
__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
	    pgprot_t prot)
{
	struct page *page;
	struct vm_region *c;
	unsigned long order;
	u64 mask = ISA_DMA_THRESHOLD, limit;

	if (!consistent_pte) {
		printk(KERN_ERR "%s: not initialised\n", __func__);
		dump_stack();
		return NULL;
	}

	if (dev) {
		mask = dev->coherent_dma_mask;

		/*
		 * Sanity check the DMA mask - it must be non-zero, and
		 * must be able to be satisfied by a DMA allocation.
		 */
		if (mask == 0) {
			dev_warn(dev, "coherent DMA mask is unset\n");
			goto no_page;
		}

		if ((~mask) & ISA_DMA_THRESHOLD) {
			dev_warn(dev, "coherent DMA mask %#llx is smaller "
				 "than system GFP_DMA mask %#llx\n",
				 mask, (unsigned long long)ISA_DMA_THRESHOLD);
			goto no_page;
		}
	}

	/*
	 * Sanity check the allocation size.
	 */
	size = PAGE_ALIGN(size);
	limit = (mask + 1) & ~mask;
	if ((limit && size >= limit) ||
	    size >= (CONSISTENT_END - CONSISTENT_BASE)) {
		printk(KERN_WARNING "coherent allocation too big "
		       "(requested %#x mask %#llx)\n", size, mask);
		goto no_page;
	}

	order = get_order(size);

	if (mask != 0xffffffff)
		gfp |= GFP_DMA;

	page = alloc_pages(gfp, order);
	if (!page)
		goto no_page;

	/*
	 * Invalidate any data that might be lurking in the
	 * kernel direct-mapped region for device DMA.
	 */
	{
		unsigned long kaddr = (unsigned long)page_address(page);
		memset(page_address(page), 0, size);
		dmac_flush_range(kaddr, kaddr + size);
	}

	/*
	 * Allocate a virtual address in the consistent mapping region.
	 */
	c = vm_region_alloc(&consistent_head, size,
			    gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
	if (c) {
		pte_t *pte = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
		struct page *end = page + (1 << order);

		c->vm_pages = page;

		/*
		 * Set the "dma handle"
		 */
		*handle = page_to_dma(dev, page);

		do {
			BUG_ON(!pte_none(*pte));

			set_page_count(page, 1);
			/*
			 * x86 does not mark the pages reserved...
			 */
			SetPageReserved(page);
			set_pte(pte, mk_pte(page, prot));
			page++;
			pte++;
		} while (size -= PAGE_SIZE);

		/*
		 * Free the otherwise unused pages.
		 */
		while (page < end) {
			set_page_count(page, 1);
			__free_page(page);
			page++;
		}

		return (void *)c->vm_start;
	}

	if (page)
		__free_pages(page, order);
 no_page:
	*handle = ~0;
	return NULL;
}

/*
 * Allocate DMA-coherent memory space and return both the kernel remapped
 * virtual and bus address for that space.
 */
void *
dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
{
	return __dma_alloc(dev, size, handle, gfp,
			   pgprot_noncached(pgprot_kernel));
}
EXPORT_SYMBOL(dma_alloc_coherent);

/*
 * Allocate a writecombining region, in much the same way as
 * dma_alloc_coherent above.
 */
void *
dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
{
	return __dma_alloc(dev, size, handle, gfp,
			   pgprot_writecombine(pgprot_kernel));
}
EXPORT_SYMBOL(dma_alloc_writecombine);

static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
		    void *cpu_addr, dma_addr_t dma_addr, size_t size)
{
	unsigned long flags, user_size, kern_size;
	struct vm_region *c;
	int ret = -ENXIO;

	user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;

	spin_lock_irqsave(&consistent_lock, flags);
	c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);
	spin_unlock_irqrestore(&consistent_lock, flags);

	if (c) {
		unsigned long off = vma->vm_pgoff;

		kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT;

		if (off < kern_size &&
		    user_size <= (kern_size - off)) {
			vma->vm_flags |= VM_RESERVED;
			ret = remap_pfn_range(vma, vma->vm_start,
					      page_to_pfn(c->vm_pages) + off,
					      user_size << PAGE_SHIFT,
					      vma->vm_page_prot);
		}
	}

	return ret;
}

int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
		      void *cpu_addr, dma_addr_t dma_addr, size_t size)
{
	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
	return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
}
EXPORT_SYMBOL(dma_mmap_coherent);

int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
			  void *cpu_addr, dma_addr_t dma_addr, size_t size)
{
	vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
	return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
}
EXPORT_SYMBOL(dma_mmap_writecombine);

/*
 * free a page as defined by the above mapping.
 * Must not be called with IRQs disabled.
 */
void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
{
	struct vm_region *c;
	unsigned long flags, addr;
	pte_t *ptep;

	WARN_ON(irqs_disabled());

	size = PAGE_ALIGN(size);

	spin_lock_irqsave(&consistent_lock, flags);
	c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);
	if (!c)
		goto no_area;

	c->vm_active = 0;
	spin_unlock_irqrestore(&consistent_lock, flags);

	if ((c->vm_end - c->vm_start) != size) {
		printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
		       __func__, c->vm_end - c->vm_start, size);
		dump_stack();
		size = c->vm_end - c->vm_start;
	}

	ptep = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
	addr = c->vm_start;
	do {
		pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
		unsigned long pfn;

		ptep++;
		addr += PAGE_SIZE;

		if (!pte_none(pte) && pte_present(pte)) {
			pfn = pte_pfn(pte);

			if (pfn_valid(pfn)) {
				struct page *page = pfn_to_page(pfn);

				/*
				 * x86 does not mark the pages reserved...
				 */
				ClearPageReserved(page);

				__free_page(page);
				continue;
			}
		}

		printk(KERN_CRIT "%s: bad page in kernel page table\n",
		       __func__);
	} while (size -= PAGE_SIZE);

	flush_tlb_kernel_range(c->vm_start, c->vm_end);

	spin_lock_irqsave(&consistent_lock, flags);
	list_del(&c->vm_list);
	spin_unlock_irqrestore(&consistent_lock, flags);

	kfree(c);
	return;

 no_area:
	spin_unlock_irqrestore(&consistent_lock, flags);
	printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
	       __func__, cpu_addr);
	dump_stack();
}
EXPORT_SYMBOL(dma_free_coherent);

/*
 * Initialise the consistent memory allocation.
 */
static int __init consistent_init(void)
{
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *pte;
	int ret = 0;

	do {
		pgd = pgd_offset(&init_mm, CONSISTENT_BASE);
		pmd = pmd_alloc(&init_mm, pgd, CONSISTENT_BASE);
		if (!pmd) {
			printk(KERN_ERR "%s: no pmd tables\n", __func__);
			ret = -ENOMEM;
			break;
		}
		WARN_ON(!pmd_none(*pmd));

		pte = pte_alloc_kernel(pmd, CONSISTENT_BASE);
		if (!pte) {
			printk(KERN_ERR "%s: no pte tables\n", __func__);
			ret = -ENOMEM;
			break;
		}

		consistent_pte = pte;
	} while (0);

	return ret;
}

core_initcall(consistent_init);

/*
 * Make an area consistent for devices.
 */
void consistent_sync(void *vaddr, size_t size, int direction)
{
	unsigned long start = (unsigned long)vaddr;
	unsigned long end   = start + size;

	switch (direction) {
	case DMA_FROM_DEVICE:		/* invalidate only */
		dmac_inv_range(start, end);
		break;
	case DMA_TO_DEVICE:		/* writeback only */
		dmac_clean_range(start, end);
		break;
	case DMA_BIDIRECTIONAL:		/* writeback and invalidate */
		dmac_flush_range(start, end);
		break;
	default:
		BUG();
	}
}
EXPORT_SYMBOL(consistent_sync);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/arch/arm/mm/consistent.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/slab.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
	21	#include <asm/cacheflush.h>
	22	#include <asm/io.h>
	23	#include <asm/tlbflush.h>
	24
	25	#define CONSISTENT_BASE (0xffc00000)
	26	#define CONSISTENT_END (0xffe00000)
	27	#define CONSISTENT_OFFSET(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
	28
	29	/*
	30	* This is the page table (2MB) covering uncached, DMA consistent allocations
	31	*/
	32	static pte_t *consistent_pte;
	33	static DEFINE_SPINLOCK(consistent_lock);
	34
	35	/*
	36	* VM region handling support.
	37	*
	38	* This should become something generic, handling VM region allocations for
	39	* vmalloc and similar (ioremap, module space, etc).
	40	*
	41	* I envisage vmalloc()'s supporting vm_struct becoming:
	42	*
	43	* struct vm_struct {
	44	* struct vm_region region;
	45	* unsigned long flags;
	46	* struct page **pages;
	47	* unsigned int nr_pages;
	48	* unsigned long phys_addr;
	49	* };
	50	*
	51	* get_vm_area() would then call vm_region_alloc with an appropriate
	52	* struct vm_region head (eg):
	53	*
	54	* struct vm_region vmalloc_head = {
	55	* .vm_list = LIST_HEAD_INIT(vmalloc_head.vm_list),
	56	* .vm_start = VMALLOC_START,
	57	* .vm_end = VMALLOC_END,
	58	* };
	59	*
	60	* However, vmalloc_head.vm_start is variable (typically, it is dependent on
	61	* the amount of RAM found at boot time.) I would imagine that get_vm_area()
	62	* would have to initialise this each time prior to calling vm_region_alloc().
	63	*/
	64	struct vm_region {
65	struct list_head vm_list;
66	unsigned long vm_start;
67	unsigned long vm_end;
68	struct page *vm_pages;
5edf71ae	69	int vm_active;
1da177e4 LT	70	};
	71
	72	static struct vm_region consistent_head = {
	73	.vm_list = LIST_HEAD_INIT(consistent_head.vm_list),
	74	.vm_start = CONSISTENT_BASE,
	75	.vm_end = CONSISTENT_END,
	76	};
	77
	78	static struct vm_region *
f9e3214a	79	vm_region_alloc(struct vm_region *head, size_t size, gfp_t gfp)
1da177e4 LT	80	{
	81	unsigned long addr = head->vm_start, end = head->vm_end - size;
	82	unsigned long flags;
	83	struct vm_region c, new;
	84
	85	new = kmalloc(sizeof(struct vm_region), gfp);
	86	if (!new)
	87	goto out;
	88
	89	spin_lock_irqsave(&consistent_lock, flags);
	90
	91	list_for_each_entry(c, &head->vm_list, vm_list) {
	92	if ((addr + size) < addr)
	93	goto nospc;
	94	if ((addr + size) <= c->vm_start)
	95	goto found;
	96	addr = c->vm_end;
	97	if (addr > end)
	98	goto nospc;
	99	}
	100
	101	found:
	102	/*
	103	* Insert this entry _before_ the one we found.
	104	*/
	105	list_add_tail(&new->vm_list, &c->vm_list);
	106	new->vm_start = addr;
	107	new->vm_end = addr + size;
5edf71ae	108	new->vm_active = 1;
1da177e4 LT	109
	110	spin_unlock_irqrestore(&consistent_lock, flags);
	111	return new;
	112
	113	nospc:
	114	spin_unlock_irqrestore(&consistent_lock, flags);
	115	kfree(new);
	116	out:
	117	return NULL;
	118	}
	119
	120	static struct vm_region vm_region_find(struct vm_region head, unsigned long addr)
	121	{
	122	struct vm_region *c;
	123
	124	list_for_each_entry(c, &head->vm_list, vm_list) {
5edf71ae	125	if (c->vm_active && c->vm_start == addr)
1da177e4 LT	126	goto out;
	127	}
	128	c = NULL;
	129	out:
	130	return c;
	131	}
	132
	133	#ifdef CONFIG_HUGETLB_PAGE
	134	#error ARM Coherent DMA allocator does not (yet) support huge TLB
	135	#endif
	136
	137	static void *
f9e3214a	138	__dma_alloc(struct device dev, size_t size, dma_addr_t handle, gfp_t gfp,
1da177e4 LT	139	pgprot_t prot)
	140	{
	141	struct page *page;
	142	struct vm_region *c;
	143	unsigned long order;
	144	u64 mask = ISA_DMA_THRESHOLD, limit;
	145
	146	if (!consistent_pte) {
	147	printk(KERN_ERR "%s: not initialised\n", __func__);
	148	dump_stack();
	149	return NULL;
	150	}
	151
	152	if (dev) {
	153	mask = dev->coherent_dma_mask;
	154
	155	/*
	156	* Sanity check the DMA mask - it must be non-zero, and
	157	* must be able to be satisfied by a DMA allocation.
	158	*/
	159	if (mask == 0) {
	160	dev_warn(dev, "coherent DMA mask is unset\n");
	161	goto no_page;
	162	}
	163
	164	if ((~mask) & ISA_DMA_THRESHOLD) {
	165	dev_warn(dev, "coherent DMA mask %#llx is smaller "
	166	"than system GFP_DMA mask %#llx\n",
	167	mask, (unsigned long long)ISA_DMA_THRESHOLD);
	168	goto no_page;
	169	}
	170	}
	171
	172	/*
	173	* Sanity check the allocation size.
	174	*/
	175	size = PAGE_ALIGN(size);
	176	limit = (mask + 1) & ~mask;
	177	if ((limit && size >= limit) \|\|
	178	size >= (CONSISTENT_END - CONSISTENT_BASE)) {
	179	printk(KERN_WARNING "coherent allocation too big "
	180	"(requested %#x mask %#llx)\n", size, mask);
	181	goto no_page;
	182	}
	183
	184	order = get_order(size);
	185
	186	if (mask != 0xffffffff)
	187	gfp \|= GFP_DMA;
	188
	189	page = alloc_pages(gfp, order);
	190	if (!page)
	191	goto no_page;
	192
	193	/*
	194	* Invalidate any data that might be lurking in the
	195	* kernel direct-mapped region for device DMA.
	196	*/
	197	{
	198	unsigned long kaddr = (unsigned long)page_address(page);
	199	memset(page_address(page), 0, size);
	200	dmac_flush_range(kaddr, kaddr + size);
	201	}
	202
203	/*
204	* Allocate a virtual address in the consistent mapping region.
205	*/
206	c = vm_region_alloc(&consistent_head, size,
207	gfp & ~(__GFP_DMA \| __GFP_HIGHMEM));
208	if (c) {
209	pte_t *pte = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
210	struct page *end = page + (1 << order);
211
212	c->vm_pages = page;
213
214	/*
215	* Set the "dma handle"
216	*/
217	*handle = page_to_dma(dev, page);
218
219	do {
220	BUG_ON(!pte_none(*pte));
221
222	set_page_count(page, 1);
223	/*
224	* x86 does not mark the pages reserved...
225	*/
226	SetPageReserved(page);
227	set_pte(pte, mk_pte(page, prot));
228	page++;
229	pte++;
230	} while (size -= PAGE_SIZE);
231
232	/*
233	* Free the otherwise unused pages.
234	*/
235	while (page < end) {
236	set_page_count(page, 1);
237	__free_page(page);
238	page++;
239	}
240
241	return (void *)c->vm_start;
242	}
243
244	if (page)
245	__free_pages(page, order);
246	no_page:
247	*handle = ~0;
248	return NULL;
249	}
250
251	/*
252	* Allocate DMA-coherent memory space and return both the kernel remapped
253	* virtual and bus address for that space.
254	*/
255	void *
f9e3214a	256	dma_alloc_coherent(struct device dev, size_t size, dma_addr_t handle, gfp_t gfp)
1da177e4 LT	257	{
	258	return __dma_alloc(dev, size, handle, gfp,
	259	pgprot_noncached(pgprot_kernel));
	260	}
	261	EXPORT_SYMBOL(dma_alloc_coherent);
	262
	263	/*
	264	* Allocate a writecombining region, in much the same way as
	265	* dma_alloc_coherent above.
	266	*/
	267	void *
f9e3214a	268	dma_alloc_writecombine(struct device dev, size_t size, dma_addr_t handle, gfp_t gfp)
1da177e4 LT	269	{
	270	return __dma_alloc(dev, size, handle, gfp,
	271	pgprot_writecombine(pgprot_kernel));
	272	}
	273	EXPORT_SYMBOL(dma_alloc_writecombine);
	274
	275	static int dma_mmap(struct device dev, struct vm_area_struct vma,
	276	void *cpu_addr, dma_addr_t dma_addr, size_t size)
	277	{
	278	unsigned long flags, user_size, kern_size;
	279	struct vm_region *c;
	280	int ret = -ENXIO;
	281
	282	user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
	283
	284	spin_lock_irqsave(&consistent_lock, flags);
	285	c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);
	286	spin_unlock_irqrestore(&consistent_lock, flags);
	287
	288	if (c) {
	289	unsigned long off = vma->vm_pgoff;
	290
	291	kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT;
	292
	293	if (off < kern_size &&
	294	user_size <= (kern_size - off)) {
	295	vma->vm_flags \|= VM_RESERVED;
	296	ret = remap_pfn_range(vma, vma->vm_start,
	297	page_to_pfn(c->vm_pages) + off,
	298	user_size << PAGE_SHIFT,
	299	vma->vm_page_prot);
	300	}
	301	}
	302
	303	return ret;
	304	}
	305
	306	int dma_mmap_coherent(struct device dev, struct vm_area_struct vma,
	307	void *cpu_addr, dma_addr_t dma_addr, size_t size)
	308	{
	309	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
	310	return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
	311	}
	312	EXPORT_SYMBOL(dma_mmap_coherent);
	313
	314	int dma_mmap_writecombine(struct device dev, struct vm_area_struct vma,
	315	void *cpu_addr, dma_addr_t dma_addr, size_t size)
	316	{
	317	vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
	318	return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
	319	}
	320	EXPORT_SYMBOL(dma_mmap_writecombine);
	321
	322	/*
	323	* free a page as defined by the above mapping.
5edf71ae	324	* Must not be called with IRQs disabled.
1da177e4 LT	325	*/
	326	void dma_free_coherent(struct device dev, size_t size, void cpu_addr, dma_addr_t handle)
	327	{
	328	struct vm_region *c;
	329	unsigned long flags, addr;
	330	pte_t *ptep;
	331
5edf71ae RK	332	WARN_ON(irqs_disabled());
5edf71ae RK	333
1da177e4 LT	334	size = PAGE_ALIGN(size);
	335
	336	spin_lock_irqsave(&consistent_lock, flags);
1da177e4 LT	337	c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);
	338	if (!c)
	339	goto no_area;
	340
5edf71ae RK	341	c->vm_active = 0;
	342	spin_unlock_irqrestore(&consistent_lock, flags);
	343
1da177e4 LT	344	if ((c->vm_end - c->vm_start) != size) {
	345	printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
	346	__func__, c->vm_end - c->vm_start, size);
	347	dump_stack();
	348	size = c->vm_end - c->vm_start;
	349	}
	350
	351	ptep = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
	352	addr = c->vm_start;
	353	do {
	354	pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
	355	unsigned long pfn;
	356
	357	ptep++;
	358	addr += PAGE_SIZE;
	359
	360	if (!pte_none(pte) && pte_present(pte)) {
	361	pfn = pte_pfn(pte);
	362
	363	if (pfn_valid(pfn)) {
	364	struct page *page = pfn_to_page(pfn);
	365
	366	/*
	367	* x86 does not mark the pages reserved...
	368	*/
	369	ClearPageReserved(page);
	370
	371	__free_page(page);
	372	continue;
	373	}
	374	}
	375
	376	printk(KERN_CRIT "%s: bad page in kernel page table\n",
	377	__func__);
	378	} while (size -= PAGE_SIZE);
	379
	380	flush_tlb_kernel_range(c->vm_start, c->vm_end);
	381
5edf71ae	382	spin_lock_irqsave(&consistent_lock, flags);
1da177e4	383	list_del(&c->vm_list);
1da177e4 LT	384	spin_unlock_irqrestore(&consistent_lock, flags);
	385
	386	kfree(c);
	387	return;
	388
	389	no_area:
	390	spin_unlock_irqrestore(&consistent_lock, flags);
	391	printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
	392	__func__, cpu_addr);
	393	dump_stack();
	394	}
	395	EXPORT_SYMBOL(dma_free_coherent);
	396
	397	/*
	398	* Initialise the consistent memory allocation.
	399	*/
	400	static int __init consistent_init(void)
	401	{
	402	pgd_t *pgd;
	403	pmd_t *pmd;
	404	pte_t *pte;
	405	int ret = 0;
	406
1da177e4 LT	407	do {
	408	pgd = pgd_offset(&init_mm, CONSISTENT_BASE);
	409	pmd = pmd_alloc(&init_mm, pgd, CONSISTENT_BASE);
	410	if (!pmd) {
	411	printk(KERN_ERR "%s: no pmd tables\n", __func__);
	412	ret = -ENOMEM;
	413	break;
	414	}
	415	WARN_ON(!pmd_none(*pmd));
	416
872fec16	417	pte = pte_alloc_kernel(pmd, CONSISTENT_BASE);
1da177e4 LT	418	if (!pte) {
	419	printk(KERN_ERR "%s: no pte tables\n", __func__);
	420	ret = -ENOMEM;
	421	break;
	422	}
	423
	424	consistent_pte = pte;
	425	} while (0);
	426
1da177e4 LT	427	return ret;
	428	}
	429
	430	core_initcall(consistent_init);
	431
	432	/*
	433	* Make an area consistent for devices.
	434	*/
	435	void consistent_sync(void *vaddr, size_t size, int direction)
	436	{
	437	unsigned long start = (unsigned long)vaddr;
	438	unsigned long end = start + size;
	439
	440	switch (direction) {
	441	case DMA_FROM_DEVICE: /* invalidate only */
	442	dmac_inv_range(start, end);
	443	break;
	444	case DMA_TO_DEVICE: /* writeback only */
	445	dmac_clean_range(start, end);
	446	break;
	447	case DMA_BIDIRECTIONAL: /* writeback and invalidate */
	448	dmac_flush_range(start, end);
	449	break;
	450	default:
	451	BUG();
	452	}
	453	}
	454	EXPORT_SYMBOL(consistent_sync);