[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / powerpc / mm / dma-noncoherent.c

/*
 *  PowerPC version derived from arch/arm/mm/consistent.c
 *    Copyright (C) 2001 Dan Malek (dmalek@jlc.net)
 *
 *  Copyright (C) 2000 Russell King
 *
 * Consistent memory allocators.  Used for DMA devices that want to
 * share uncached memory with the processor core.  The function return
 * is the virtual address and 'dma_handle' is the physical address.
 * Mostly stolen from the ARM port, with some changes for PowerPC.
 *						-- Dan
 *
 * Reorganized to get rid of the arch-specific consistent_* functions
 * and provide non-coherent implementations for the DMA API. -Matt
 *
 * Added in_interrupt() safe dma_alloc_coherent()/dma_free_coherent()
 * implementation. This is pulled straight from ARM and barely
 * modified. -Matt
 *
 * 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.
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/highmem.h>
#include <linux/dma-mapping.h>

#include <asm/tlbflush.h>

#include "mmu_decl.h"

/*
 * This address range defaults to a value that is safe for all
 * platforms which currently set CONFIG_NOT_COHERENT_CACHE. It
 * can be further configured for specific applications under
 * the "Advanced Setup" menu. -Matt
 */
#define CONSISTENT_BASE		(IOREMAP_TOP)
#define CONSISTENT_END 		(CONSISTENT_BASE + CONFIG_CONSISTENT_SIZE)
#define CONSISTENT_OFFSET(x)	(((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)

/*
 * This is the page table (2MB) covering uncached, DMA consistent allocations
 */
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 ppc_vm_region {
	struct list_head	vm_list;
	unsigned long		vm_start;
	unsigned long		vm_end;
};

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

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

	new = kmalloc(sizeof(struct ppc_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;

	spin_unlock_irqrestore(&consistent_lock, flags);
	return new;

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

static struct ppc_vm_region *ppc_vm_region_find(struct ppc_vm_region *head, unsigned long addr)
{
	struct ppc_vm_region *c;

	list_for_each_entry(c, &head->vm_list, vm_list) {
		if (c->vm_start == addr)
			goto out;
	}
	c = NULL;
 out:
	return c;
}

/*
 * 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)
{
	struct page *page;
	struct ppc_vm_region *c;
	unsigned long order;
	u64 mask = ISA_DMA_THRESHOLD, limit;

	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;
		}
	}


	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 %#Lx)\n",
		       size, mask);
		return NULL;
	}

	order = get_order(size);

	/* Might be useful if we ever have a real legacy DMA zone... */
	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);
		flush_dcache_range(kaddr, kaddr + size);
	}

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

		split_page(page, order);

		/*
		 * Set the "dma handle"
		 */
		*handle = page_to_phys(page);

		do {
			SetPageReserved(page);
			map_page(vaddr, page_to_phys(page),
				 pgprot_noncached(PAGE_KERNEL));
			page++;
			vaddr += PAGE_SIZE;
		} while (size -= PAGE_SIZE);

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

		return (void *)c->vm_start;
	}

	if (page)
		__free_pages(page, order);
 no_page:
	return NULL;
}
EXPORT_SYMBOL(__dma_alloc_coherent);

/*
 * free a page as defined by the above mapping.
 */
void __dma_free_coherent(size_t size, void *vaddr)
{
	struct ppc_vm_region *c;
	unsigned long flags, addr;
	
	size = PAGE_ALIGN(size);

	spin_lock_irqsave(&consistent_lock, flags);

	c = ppc_vm_region_find(&consistent_head, (unsigned long)vaddr);
	if (!c)
		goto no_area;

	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;
	}

	addr = c->vm_start;
	do {
		pte_t *ptep;
		unsigned long pfn;

		ptep = pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(addr),
							       addr),
						    addr),
					 addr);
		if (!pte_none(*ptep) && pte_present(*ptep)) {
			pfn = pte_pfn(*ptep);
			pte_clear(&init_mm, addr, ptep);
			if (pfn_valid(pfn)) {
				struct page *page = pfn_to_page(pfn);

				ClearPageReserved(page);
				__free_page(page);
			}
		}
		addr += PAGE_SIZE;
	} while (size -= PAGE_SIZE);

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

	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__, vaddr);
	dump_stack();
}
EXPORT_SYMBOL(__dma_free_coherent);

/*
 * make an area consistent.
 */
void __dma_sync(void *vaddr, size_t size, int direction)
{
	unsigned long start = (unsigned long)vaddr;
	unsigned long end   = start + size;

	switch (direction) {
	case DMA_NONE:
		BUG();
	case DMA_FROM_DEVICE:
		/*
		 * invalidate only when cache-line aligned otherwise there is
		 * the potential for discarding uncommitted data from the cache
		 */
		if ((start & (L1_CACHE_BYTES - 1)) || (size & (L1_CACHE_BYTES - 1)))
			flush_dcache_range(start, end);
		else
			invalidate_dcache_range(start, end);
		break;
	case DMA_TO_DEVICE:		/* writeback only */
		clean_dcache_range(start, end);
		break;
	case DMA_BIDIRECTIONAL:	/* writeback and invalidate */
		flush_dcache_range(start, end);
		break;
	}
}
EXPORT_SYMBOL(__dma_sync);

#ifdef CONFIG_HIGHMEM
/*
 * __dma_sync_page() implementation for systems using highmem.
 * In this case, each page of a buffer must be kmapped/kunmapped
 * in order to have a virtual address for __dma_sync(). This must
 * not sleep so kmap_atomic()/kunmap_atomic() are used.
 *
 * Note: yes, it is possible and correct to have a buffer extend
 * beyond the first page.
 */
static inline void __dma_sync_page_highmem(struct page *page,
		unsigned long offset, size_t size, int direction)
{
	size_t seg_size = min((size_t)(PAGE_SIZE - offset), size);
	size_t cur_size = seg_size;
	unsigned long flags, start, seg_offset = offset;
	int nr_segs = 1 + ((size - seg_size) + PAGE_SIZE - 1)/PAGE_SIZE;
	int seg_nr = 0;

	local_irq_save(flags);

	do {
		start = (unsigned long)kmap_atomic(page + seg_nr,
				KM_PPC_SYNC_PAGE) + seg_offset;

		/* Sync this buffer segment */
		__dma_sync((void *)start, seg_size, direction);
		kunmap_atomic((void *)start, KM_PPC_SYNC_PAGE);
		seg_nr++;

		/* Calculate next buffer segment size */
		seg_size = min((size_t)PAGE_SIZE, size - cur_size);

		/* Add the segment size to our running total */
		cur_size += seg_size;
		seg_offset = 0;
	} while (seg_nr < nr_segs);

	local_irq_restore(flags);
}
#endif /* CONFIG_HIGHMEM */

/*
 * __dma_sync_page makes memory consistent. identical to __dma_sync, but
 * takes a struct page instead of a virtual address
 */
void __dma_sync_page(struct page *page, unsigned long offset,
	size_t size, int direction)
{
#ifdef CONFIG_HIGHMEM
	__dma_sync_page_highmem(page, offset, size, direction);
#else
	unsigned long start = (unsigned long)page_address(page) + offset;
	__dma_sync((void *)start, size, direction);
#endif
}
EXPORT_SYMBOL(__dma_sync_page);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* PowerPC version derived from arch/arm/mm/consistent.c
	3	* Copyright (C) 2001 Dan Malek (dmalek@jlc.net)
	4	*
	5	* Copyright (C) 2000 Russell King
	6	*
	7	* Consistent memory allocators. Used for DMA devices that want to
	8	* share uncached memory with the processor core. The function return
	9	* is the virtual address and 'dma_handle' is the physical address.
	10	* Mostly stolen from the ARM port, with some changes for PowerPC.
	11	* -- Dan
	12	*
	13	* Reorganized to get rid of the arch-specific consistent_* functions
	14	* and provide non-coherent implementations for the DMA API. -Matt
	15	*
	16	* Added in_interrupt() safe dma_alloc_coherent()/dma_free_coherent()
	17	* implementation. This is pulled straight from ARM and barely
	18	* modified. -Matt
	19	*
	20	* This program is free software; you can redistribute it and/or modify
	21	* it under the terms of the GNU General Public License version 2 as
	22	* published by the Free Software Foundation.
	23	*/
	24
1da177e4	25	#include <linux/sched.h>
5a0e3ad6	26	#include <linux/slab.h>
1da177e4 LT	27	#include <linux/kernel.h>
	28	#include <linux/errno.h>
	29	#include <linux/string.h>
	30	#include <linux/types.h>
1da177e4 LT	31	#include <linux/highmem.h>
1da177e4 LT	32	#include <linux/dma-mapping.h>
1da177e4 LT	33
	34	#include <asm/tlbflush.h>
	35
8b31e49d BH	36	#include "mmu_decl.h"
8b31e49d BH	37
84532a0f BH	38	/*
	39	* This address range defaults to a value that is safe for all
	40	* platforms which currently set CONFIG_NOT_COHERENT_CACHE. It
	41	* can be further configured for specific applications under
	42	* the "Advanced Setup" menu. -Matt
	43	*/
8b31e49d BH	44	#define CONSISTENT_BASE (IOREMAP_TOP)
8b31e49d BH	45	#define CONSISTENT_END (CONSISTENT_BASE + CONFIG_CONSISTENT_SIZE)
84532a0f BH	46	#define CONSISTENT_OFFSET(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
	47
	48	/*
	49	* This is the page table (2MB) covering uncached, DMA consistent allocations
	50	*/
84532a0f BH	51	static DEFINE_SPINLOCK(consistent_lock);
	52
	53	/*
	54	* VM region handling support.
	55	*
	56	* This should become something generic, handling VM region allocations for
	57	* vmalloc and similar (ioremap, module space, etc).
	58	*
	59	* I envisage vmalloc()'s supporting vm_struct becoming:
	60	*
	61	* struct vm_struct {
	62	* struct vm_region region;
	63	* unsigned long flags;
	64	* struct page **pages;
	65	* unsigned int nr_pages;
	66	* unsigned long phys_addr;
	67	* };
	68	*
	69	* get_vm_area() would then call vm_region_alloc with an appropriate
	70	* struct vm_region head (eg):
	71	*
	72	* struct vm_region vmalloc_head = {
	73	* .vm_list = LIST_HEAD_INIT(vmalloc_head.vm_list),
	74	* .vm_start = VMALLOC_START,
	75	* .vm_end = VMALLOC_END,
	76	* };
	77	*
	78	* However, vmalloc_head.vm_start is variable (typically, it is dependent on
	79	* the amount of RAM found at boot time.) I would imagine that get_vm_area()
	80	* would have to initialise this each time prior to calling vm_region_alloc().
	81	*/
	82	struct ppc_vm_region {
	83	struct list_head vm_list;
	84	unsigned long vm_start;
	85	unsigned long vm_end;
	86	};
	87
	88	static struct ppc_vm_region consistent_head = {
	89	.vm_list = LIST_HEAD_INIT(consistent_head.vm_list),
	90	.vm_start = CONSISTENT_BASE,
	91	.vm_end = CONSISTENT_END,
	92	};
	93
	94	static struct ppc_vm_region *
	95	ppc_vm_region_alloc(struct ppc_vm_region *head, size_t size, gfp_t gfp)
	96	{
	97	unsigned long addr = head->vm_start, end = head->vm_end - size;
	98	unsigned long flags;
	99	struct ppc_vm_region c, new;
	100
	101	new = kmalloc(sizeof(struct ppc_vm_region), gfp);
	102	if (!new)
	103	goto out;
	104
	105	spin_lock_irqsave(&consistent_lock, flags);
	106
	107	list_for_each_entry(c, &head->vm_list, vm_list) {
	108	if ((addr + size) < addr)
	109	goto nospc;
	110	if ((addr + size) <= c->vm_start)
	111	goto found;
	112	addr = c->vm_end;
	113	if (addr > end)
	114	goto nospc;
115	}
116
117	found:
118	/*
119	* Insert this entry _before_ the one we found.
120	*/
121	list_add_tail(&new->vm_list, &c->vm_list);
122	new->vm_start = addr;
123	new->vm_end = addr + size;
124
125	spin_unlock_irqrestore(&consistent_lock, flags);
126	return new;
127
128	nospc:
129	spin_unlock_irqrestore(&consistent_lock, flags);
130	kfree(new);
131	out:
132	return NULL;
133	}
134
135	static struct ppc_vm_region ppc_vm_region_find(struct ppc_vm_region head, unsigned long addr)
136	{
137	struct ppc_vm_region *c;
138
139	list_for_each_entry(c, &head->vm_list, vm_list) {
140	if (c->vm_start == addr)
141	goto out;
142	}
143	c = NULL;
144	out:
145	return c;
146	}
147
1da177e4 LT	148	/*
	149	* Allocate DMA-coherent memory space and return both the kernel remapped
	150	* virtual and bus address for that space.
	151	*/
	152	void *
8b31e49d	153	__dma_alloc_coherent(struct device dev, size_t size, dma_addr_t handle, gfp_t gfp)
1da177e4 LT	154	{
1da177e4 LT	155	struct page *page;
84532a0f	156	struct ppc_vm_region *c;
1da177e4	157	unsigned long order;
8b31e49d	158	u64 mask = ISA_DMA_THRESHOLD, limit;
1da177e4	159
8b31e49d BH	160	if (dev) {
	161	mask = dev->coherent_dma_mask;
	162
	163	/*
	164	* Sanity check the DMA mask - it must be non-zero, and
	165	* must be able to be satisfied by a DMA allocation.
	166	*/
	167	if (mask == 0) {
	168	dev_warn(dev, "coherent DMA mask is unset\n");
	169	goto no_page;
	170	}
	171
	172	if ((~mask) & ISA_DMA_THRESHOLD) {
	173	dev_warn(dev, "coherent DMA mask %#llx is smaller "
	174	"than system GFP_DMA mask %#llx\n",
	175	mask, (unsigned long long)ISA_DMA_THRESHOLD);
	176	goto no_page;
	177	}
84532a0f BH	178	}
84532a0f BH	179
8b31e49d	180
1da177e4 LT	181	size = PAGE_ALIGN(size);
1da177e4 LT	182	limit = (mask + 1) & ~mask;
8b31e49d BH	183	if ((limit && size >= limit) \|\|
8b31e49d BH	184	size >= (CONSISTENT_END - CONSISTENT_BASE)) {
84532a0f BH	185	printk(KERN_WARNING "coherent allocation too big (requested %#x mask %#Lx)\n",
84532a0f BH	186	size, mask);
1da177e4 LT	187	return NULL;
	188	}
	189
	190	order = get_order(size);
	191
8b31e49d	192	/* Might be useful if we ever have a real legacy DMA zone... */
1da177e4 LT	193	if (mask != 0xffffffff)
	194	gfp \|= GFP_DMA;
	195
	196	page = alloc_pages(gfp, order);
	197	if (!page)
	198	goto no_page;
	199
	200	/*
	201	* Invalidate any data that might be lurking in the
	202	* kernel direct-mapped region for device DMA.
	203	*/
	204	{
	205	unsigned long kaddr = (unsigned long)page_address(page);
	206	memset(page_address(page), 0, size);
	207	flush_dcache_range(kaddr, kaddr + size);
	208	}
	209
	210	/*
84532a0f	211	* Allocate a virtual address in the consistent mapping region.
1da177e4	212	*/
84532a0f BH	213	c = ppc_vm_region_alloc(&consistent_head, size,
	214	gfp & ~(__GFP_DMA \| __GFP_HIGHMEM));
	215	if (c) {
	216	unsigned long vaddr = c->vm_start;
84532a0f	217	struct page *end = page + (1 << order);
1da177e4	218
84532a0f BH	219	split_page(page, order);
	220
	221	/*
	222	* Set the "dma handle"
	223	*/
	224	*handle = page_to_phys(page);
1da177e4	225
84532a0f	226	do {
84532a0f	227	SetPageReserved(page);
8b31e49d BH	228	map_page(vaddr, page_to_phys(page),
8b31e49d BH	229	pgprot_noncached(PAGE_KERNEL));
84532a0f	230	page++;
84532a0f BH	231	vaddr += PAGE_SIZE;
84532a0f BH	232	} while (size -= PAGE_SIZE);
1da177e4	233
84532a0f BH	234	/*
	235	* Free the otherwise unused pages.
	236	*/
	237	while (page < end) {
	238	__free_page(page);
	239	page++;
	240	}
	241
	242	return (void *)c->vm_start;
1da177e4 LT	243	}
	244
	245	if (page)
	246	__free_pages(page, order);
84532a0f	247	no_page:
1da177e4 LT	248	return NULL;
	249	}
	250	EXPORT_SYMBOL(__dma_alloc_coherent);
	251
	252	/*
	253	* free a page as defined by the above mapping.
	254	*/
	255	void __dma_free_coherent(size_t size, void *vaddr)
	256	{
84532a0f BH	257	struct ppc_vm_region *c;
84532a0f BH	258	unsigned long flags, addr;
8b31e49d	259
84532a0f BH	260	size = PAGE_ALIGN(size);
	261
	262	spin_lock_irqsave(&consistent_lock, flags);
	263
	264	c = ppc_vm_region_find(&consistent_head, (unsigned long)vaddr);
	265	if (!c)
	266	goto no_area;
	267
	268	if ((c->vm_end - c->vm_start) != size) {
	269	printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
	270	__func__, c->vm_end - c->vm_start, size);
	271	dump_stack();
	272	size = c->vm_end - c->vm_start;
	273	}
	274
84532a0f BH	275	addr = c->vm_start;
84532a0f BH	276	do {
8b31e49d	277	pte_t *ptep;
84532a0f BH	278	unsigned long pfn;
84532a0f BH	279
8b31e49d BH	280	ptep = pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(addr),
	281	addr),
	282	addr),
	283	addr);
	284	if (!pte_none(ptep) && pte_present(ptep)) {
	285	pfn = pte_pfn(*ptep);
	286	pte_clear(&init_mm, addr, ptep);
84532a0f BH	287	if (pfn_valid(pfn)) {
84532a0f BH	288	struct page *page = pfn_to_page(pfn);
84532a0f	289
8b31e49d	290	ClearPageReserved(page);
84532a0f	291	__free_page(page);
84532a0f BH	292	}
84532a0f BH	293	}
8b31e49d	294	addr += PAGE_SIZE;
84532a0f BH	295	} while (size -= PAGE_SIZE);
	296
	297	flush_tlb_kernel_range(c->vm_start, c->vm_end);
	298
	299	list_del(&c->vm_list);
	300
	301	spin_unlock_irqrestore(&consistent_lock, flags);
	302
	303	kfree(c);
	304	return;
	305
	306	no_area:
	307	spin_unlock_irqrestore(&consistent_lock, flags);
	308	printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
	309	__func__, vaddr);
	310	dump_stack();
1da177e4 LT	311	}
	312	EXPORT_SYMBOL(__dma_free_coherent);
	313
1da177e4 LT	314	/*
	315	* make an area consistent.
	316	*/
	317	void __dma_sync(void *vaddr, size_t size, int direction)
	318	{
	319	unsigned long start = (unsigned long)vaddr;
	320	unsigned long end = start + size;
	321
	322	switch (direction) {
	323	case DMA_NONE:
	324	BUG();
03d70617 AL	325	case DMA_FROM_DEVICE:
	326	/*
	327	* invalidate only when cache-line aligned otherwise there is
	328	* the potential for discarding uncommitted data from the cache
	329	*/
	330	if ((start & (L1_CACHE_BYTES - 1)) \|\| (size & (L1_CACHE_BYTES - 1)))
	331	flush_dcache_range(start, end);
	332	else
	333	invalidate_dcache_range(start, end);
1da177e4 LT	334	break;
	335	case DMA_TO_DEVICE: /* writeback only */
	336	clean_dcache_range(start, end);
	337	break;
	338	case DMA_BIDIRECTIONAL: /* writeback and invalidate */
	339	flush_dcache_range(start, end);
	340	break;
	341	}
	342	}
	343	EXPORT_SYMBOL(__dma_sync);
	344
	345	#ifdef CONFIG_HIGHMEM
	346	/*
	347	* __dma_sync_page() implementation for systems using highmem.
	348	* In this case, each page of a buffer must be kmapped/kunmapped
	349	* in order to have a virtual address for __dma_sync(). This must
338cec32	350	* not sleep so kmap_atomic()/kunmap_atomic() are used.
1da177e4 LT	351	*
	352	* Note: yes, it is possible and correct to have a buffer extend
	353	* beyond the first page.
	354	*/
	355	static inline void __dma_sync_page_highmem(struct page *page,
	356	unsigned long offset, size_t size, int direction)
	357	{
a0c111c6	358	size_t seg_size = min((size_t)(PAGE_SIZE - offset), size);
1da177e4 LT	359	size_t cur_size = seg_size;
1da177e4 LT	360	unsigned long flags, start, seg_offset = offset;
a0c111c6	361	int nr_segs = 1 + ((size - seg_size) + PAGE_SIZE - 1)/PAGE_SIZE;
1da177e4 LT	362	int seg_nr = 0;
	363
	364	local_irq_save(flags);
	365
	366	do {
	367	start = (unsigned long)kmap_atomic(page + seg_nr,
	368	KM_PPC_SYNC_PAGE) + seg_offset;
	369
	370	/* Sync this buffer segment */
	371	__dma_sync((void *)start, seg_size, direction);
	372	kunmap_atomic((void *)start, KM_PPC_SYNC_PAGE);
	373	seg_nr++;
	374
	375	/* Calculate next buffer segment size */
	376	seg_size = min((size_t)PAGE_SIZE, size - cur_size);
	377
	378	/* Add the segment size to our running total */
	379	cur_size += seg_size;
	380	seg_offset = 0;
	381	} while (seg_nr < nr_segs);
	382
	383	local_irq_restore(flags);
	384	}
	385	#endif /* CONFIG_HIGHMEM */
	386
	387	/*
	388	* __dma_sync_page makes memory consistent. identical to __dma_sync, but
	389	* takes a struct page instead of a virtual address
	390	*/
	391	void __dma_sync_page(struct page *page, unsigned long offset,
	392	size_t size, int direction)
	393	{
	394	#ifdef CONFIG_HIGHMEM
	395	__dma_sync_page_highmem(page, offset, size, direction);
	396	#else
	397	unsigned long start = (unsigned long)page_address(page) + offset;
	398	__dma_sync((void *)start, size, direction);
	399	#endif
	400	}
	401	EXPORT_SYMBOL(__dma_sync_page);