[net-next-2.6.git] / arch / ppc / mm / pgtable.c

/*
 * This file contains the routines setting up the linux page tables.
 *  -- paulus
 *
 *  Derived from arch/ppc/mm/init.c:
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
 *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
 *    Copyright (C) 1996 Paul Mackerras
 *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
 *
 *  Derived from "arch/i386/mm/init.c"
 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/highmem.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/io.h>

#include "mmu_decl.h"

unsigned long ioremap_base;
unsigned long ioremap_bot;
int io_bat_index;

#if defined(CONFIG_6xx)
#define HAVE_BATS	1
#endif

extern char etext[], _stext[];

#ifdef CONFIG_SMP
extern void hash_page_sync(void);
#endif

#ifdef HAVE_BATS
extern unsigned long v_mapped_by_bats(unsigned long va);
extern unsigned long p_mapped_by_bats(unsigned long pa);
void setbat(int index, unsigned long virt, unsigned long phys,
	    unsigned int size, int flags);

#else /* !HAVE_BATS */
#define v_mapped_by_bats(x)	(0UL)
#define p_mapped_by_bats(x)	(0UL)
#endif /* HAVE_BATS */

#ifdef CONFIG_PTE_64BIT
/* 44x uses an 8kB pgdir because it has 8-byte Linux PTEs. */
#define PGDIR_ORDER	1
#else
#define PGDIR_ORDER	0
#endif

pgd_t *pgd_alloc(struct mm_struct *mm)
{
	pgd_t *ret;

	ret = (pgd_t *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, PGDIR_ORDER);
	return ret;
}

void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
	free_pages((unsigned long)pgd, PGDIR_ORDER);
}

__init_refok pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
{
	pte_t *pte;
	extern int mem_init_done;
	extern void *early_get_page(void);

	if (mem_init_done) {
		pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
	} else {
		pte = (pte_t *)early_get_page();
		if (pte)
			clear_page(pte);
	}
	return pte;
}

pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
	struct page *ptepage;

#ifdef CONFIG_HIGHPTE
	gfp_t flags = GFP_KERNEL | __GFP_HIGHMEM | __GFP_REPEAT;
#else
	gfp_t flags = GFP_KERNEL | __GFP_REPEAT;
#endif

	ptepage = alloc_pages(flags, 0);
	if (ptepage) {
		clear_highpage(ptepage);
		pgtable_page_ctor(ptepage);
	}
	return ptepage;
}

void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
{
#ifdef CONFIG_SMP
	hash_page_sync();
#endif
	free_page((unsigned long)pte);
}

void pte_free(struct mm_struct *mm, pgtable_t ptepage)
{
#ifdef CONFIG_SMP
	hash_page_sync();
#endif
	pgtable_page_dtor(ptepage);
	__free_page(ptepage);
}

#ifndef CONFIG_PHYS_64BIT
void __iomem *
ioremap(phys_addr_t addr, unsigned long size)
{
	return __ioremap(addr, size, _PAGE_NO_CACHE);
}
#else /* CONFIG_PHYS_64BIT */
void __iomem *
ioremap64(unsigned long long addr, unsigned long size)
{
	return __ioremap(addr, size, _PAGE_NO_CACHE);
}

void __iomem *
ioremap(phys_addr_t addr, unsigned long size)
{
	phys_addr_t addr64 = fixup_bigphys_addr(addr, size);

	return ioremap64(addr64, size);
}
#endif /* CONFIG_PHYS_64BIT */

void __iomem *
__ioremap(phys_addr_t addr, unsigned long size, unsigned long flags)
{
	unsigned long v, i;
	phys_addr_t p;
	int err;

	/*
	 * Choose an address to map it to.
	 * Once the vmalloc system is running, we use it.
	 * Before then, we use space going down from ioremap_base
	 * (ioremap_bot records where we're up to).
	 */
	p = addr & PAGE_MASK;
	size = PAGE_ALIGN(addr + size) - p;

	/*
	 * If the address lies within the first 16 MB, assume it's in ISA
	 * memory space
	 */
	if (p < 16*1024*1024)
		p += _ISA_MEM_BASE;

	/*
	 * Don't allow anybody to remap normal RAM that we're using.
	 * mem_init() sets high_memory so only do the check after that.
	 */
	if ( mem_init_done && (p < virt_to_phys(high_memory)) )
	{
		printk("__ioremap(): phys addr "PHYS_FMT" is RAM lr %p\n", p,
		       __builtin_return_address(0));
		return NULL;
	}

	if (size == 0)
		return NULL;

	/*
	 * Is it already mapped?  Perhaps overlapped by a previous
	 * BAT mapping.  If the whole area is mapped then we're done,
	 * otherwise remap it since we want to keep the virt addrs for
	 * each request contiguous.
	 *
	 * We make the assumption here that if the bottom and top
	 * of the range we want are mapped then it's mapped to the
	 * same virt address (and this is contiguous).
	 *  -- Cort
	 */
	if ((v = p_mapped_by_bats(p)) /*&& p_mapped_by_bats(p+size-1)*/ )
		goto out;

	if (mem_init_done) {
		struct vm_struct *area;
		area = get_vm_area(size, VM_IOREMAP);
		if (area == 0)
			return NULL;
		v = (unsigned long) area->addr;
	} else {
		v = (ioremap_bot -= size);
	}

	if ((flags & _PAGE_PRESENT) == 0)
		flags |= _PAGE_KERNEL;
	if (flags & _PAGE_NO_CACHE)
		flags |= _PAGE_GUARDED;

	/*
	 * Should check if it is a candidate for a BAT mapping
	 */

	err = 0;
	for (i = 0; i < size && err == 0; i += PAGE_SIZE)
		err = map_page(v+i, p+i, flags);
	if (err) {
		if (mem_init_done)
			vunmap((void *)v);
		return NULL;
	}

out:
	return (void __iomem *) (v + ((unsigned long)addr & ~PAGE_MASK));
}

void iounmap(volatile void __iomem *addr)
{
	/*
	 * If mapped by BATs then there is nothing to do.
	 * Calling vfree() generates a benign warning.
	 */
	if (v_mapped_by_bats((unsigned long)addr)) return;

	if (addr > high_memory && (unsigned long) addr < ioremap_bot)
		vunmap((void *) (PAGE_MASK & (unsigned long)addr));
}

void __iomem *ioport_map(unsigned long port, unsigned int len)
{
	return (void __iomem *) (port + _IO_BASE);
}

void ioport_unmap(void __iomem *addr)
{
	/* Nothing to do */
}
EXPORT_SYMBOL(ioport_map);
EXPORT_SYMBOL(ioport_unmap);

int
map_page(unsigned long va, phys_addr_t pa, int flags)
{
	pmd_t *pd;
	pte_t *pg;
	int err = -ENOMEM;

	/* Use upper 10 bits of VA to index the first level map */
	pd = pmd_offset(pgd_offset_k(va), va);
	/* Use middle 10 bits of VA to index the second-level map */
	pg = pte_alloc_kernel(pd, va);
	if (pg != 0) {
		err = 0;
		set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT, __pgprot(flags)));
		if (mem_init_done)
			flush_HPTE(0, va, pmd_val(*pd));
	}
	return err;
}

/*
 * Map in all of physical memory starting at KERNELBASE.
 */
void __init mapin_ram(void)
{
	unsigned long v, p, s, f;

	s = mmu_mapin_ram();
	v = KERNELBASE + s;
	p = PPC_MEMSTART + s;
	for (; s < total_lowmem; s += PAGE_SIZE) {
		if ((char *) v >= _stext && (char *) v < etext)
			f = _PAGE_RAM_TEXT;
		else
			f = _PAGE_RAM;
		map_page(v, p, f);
		v += PAGE_SIZE;
		p += PAGE_SIZE;
	}
}

/* is x a power of 4? */
#define is_power_of_4(x)	is_power_of_2(x) && (ffs(x) & 1)

/*
 * Set up a mapping for a block of I/O.
 * virt, phys, size must all be page-aligned.
 * This should only be called before ioremap is called.
 */
void __init io_block_mapping(unsigned long virt, phys_addr_t phys,
			     unsigned int size, int flags)
{
	int i;

	if (virt > KERNELBASE && virt < ioremap_bot)
		ioremap_bot = ioremap_base = virt;

#ifdef HAVE_BATS
	/*
	 * Use a BAT for this if possible...
	 */
	if (io_bat_index < 2 && is_power_of_2(size)
	    && (virt & (size - 1)) == 0 && (phys & (size - 1)) == 0) {
		setbat(io_bat_index, virt, phys, size, flags);
		++io_bat_index;
		return;
	}
#endif /* HAVE_BATS */

	/* No BATs available, put it in the page tables. */
	for (i = 0; i < size; i += PAGE_SIZE)
		map_page(virt + i, phys + i, flags);
}

/* Scan the real Linux page tables and return a PTE pointer for
 * a virtual address in a context.
 * Returns true (1) if PTE was found, zero otherwise.  The pointer to
 * the PTE pointer is unmodified if PTE is not found.
 */
int
get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)
{
        pgd_t	*pgd;
        pmd_t	*pmd;
        pte_t	*pte;
        int     retval = 0;

        pgd = pgd_offset(mm, addr & PAGE_MASK);
        if (pgd) {
                pmd = pmd_offset(pgd, addr & PAGE_MASK);
                if (pmd_present(*pmd)) {
                        pte = pte_offset_map(pmd, addr & PAGE_MASK);
                        if (pte) {
				retval = 1;
				*ptep = pte;
				if (pmdp)
					*pmdp = pmd;
				/* XXX caller needs to do pte_unmap, yuck */
                        }
                }
        }
        return(retval);
}

/* Find physical address for this virtual address.  Normally used by
 * I/O functions, but anyone can call it.
 */
unsigned long iopa(unsigned long addr)
{
	unsigned long pa;

	/* I don't know why this won't work on PMacs or CHRP.  It
	 * appears there is some bug, or there is some implicit
	 * mapping done not properly represented by BATs or in page
	 * tables.......I am actively working on resolving this, but
	 * can't hold up other stuff.  -- Dan
	 */
	pte_t *pte;
	struct mm_struct *mm;

	/* Check the BATs */
	pa = v_mapped_by_bats(addr);
	if (pa)
		return pa;

	/* Allow mapping of user addresses (within the thread)
	 * for DMA if necessary.
	 */
	if (addr < TASK_SIZE)
		mm = current->mm;
	else
		mm = &init_mm;

	pa = 0;
	if (get_pteptr(mm, addr, &pte, NULL)) {
		pa = (pte_val(*pte) & PAGE_MASK) | (addr & ~PAGE_MASK);
		pte_unmap(pte);
	}

	return(pa);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* This file contains the routines setting up the linux page tables.
	3	* -- paulus
	4	*
	5	* Derived from arch/ppc/mm/init.c:
	6	* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
	7	*
	8	* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
	9	* and Cort Dougan (PReP) (cort@cs.nmt.edu)
	10	* Copyright (C) 1996 Paul Mackerras
	11	* Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
	12	*
	13	* Derived from "arch/i386/mm/init.c"
	14	* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
	15	*
	16	* This program is free software; you can redistribute it and/or
	17	* modify it under the terms of the GNU General Public License
	18	* as published by the Free Software Foundation; either version
	19	* 2 of the License, or (at your option) any later version.
	20	*
	21	*/
	22
1da177e4 LT	23	#include <linux/kernel.h>
	24	#include <linux/module.h>
	25	#include <linux/types.h>
	26	#include <linux/mm.h>
	27	#include <linux/vmalloc.h>
	28	#include <linux/init.h>
	29	#include <linux/highmem.h>
	30
	31	#include <asm/pgtable.h>
	32	#include <asm/pgalloc.h>
	33	#include <asm/io.h>
	34
	35	#include "mmu_decl.h"
	36
	37	unsigned long ioremap_base;
	38	unsigned long ioremap_bot;
	39	int io_bat_index;
	40
0a26b136	41	#if defined(CONFIG_6xx)
1da177e4 LT	42	#define HAVE_BATS 1
	43	#endif
	44
1da177e4 LT	45	extern char etext[], _stext[];
	46
	47	#ifdef CONFIG_SMP
	48	extern void hash_page_sync(void);
	49	#endif
	50
	51	#ifdef HAVE_BATS
	52	extern unsigned long v_mapped_by_bats(unsigned long va);
	53	extern unsigned long p_mapped_by_bats(unsigned long pa);
	54	void setbat(int index, unsigned long virt, unsigned long phys,
	55	unsigned int size, int flags);
	56
	57	#else /* !HAVE_BATS */
	58	#define v_mapped_by_bats(x) (0UL)
	59	#define p_mapped_by_bats(x) (0UL)
	60	#endif /* HAVE_BATS */
	61
a85f6d4a	62	#ifdef CONFIG_PTE_64BIT
1da177e4 LT	63	/* 44x uses an 8kB pgdir because it has 8-byte Linux PTEs. */
	64	#define PGDIR_ORDER 1
	65	#else
	66	#define PGDIR_ORDER 0
	67	#endif
	68
	69	pgd_t pgd_alloc(struct mm_struct mm)
	70	{
	71	pgd_t *ret;
	72
	73	ret = (pgd_t *)__get_free_pages(GFP_KERNEL\|__GFP_ZERO, PGDIR_ORDER);
	74	return ret;
	75	}
	76
5e541973	77	void pgd_free(struct mm_struct mm, pgd_t pgd)
1da177e4 LT	78	{
	79	free_pages((unsigned long)pgd, PGDIR_ORDER);
	80	}
	81
c1c9889a	82	__init_refok pte_t pte_alloc_one_kernel(struct mm_struct mm, unsigned long address)
1da177e4 LT	83	{
	84	pte_t *pte;
	85	extern int mem_init_done;
	86	extern void *early_get_page(void);
	87
	88	if (mem_init_done) {
	89	pte = (pte_t *)__get_free_page(GFP_KERNEL\|__GFP_REPEAT\|__GFP_ZERO);
	90	} else {
	91	pte = (pte_t *)early_get_page();
	92	if (pte)
	93	clear_page(pte);
	94	}
	95	return pte;
	96	}
	97
2f569afd	98	pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
1da177e4 LT	99	{
	100	struct page *ptepage;
	101
	102	#ifdef CONFIG_HIGHPTE
53f9fc93	103	gfp_t flags = GFP_KERNEL \| __GFP_HIGHMEM \| __GFP_REPEAT;
1da177e4	104	#else
53f9fc93	105	gfp_t flags = GFP_KERNEL \| __GFP_REPEAT;
1da177e4 LT	106	#endif
	107
	108	ptepage = alloc_pages(flags, 0);
2f569afd	109	if (ptepage) {
1da177e4	110	clear_highpage(ptepage);
2f569afd MS	111	pgtable_page_ctor(ptepage);
2f569afd MS	112	}
1da177e4 LT	113	return ptepage;
	114	}
	115
5e541973	116	void pte_free_kernel(struct mm_struct mm, pte_t pte)
1da177e4 LT	117	{
	118	#ifdef CONFIG_SMP
	119	hash_page_sync();
	120	#endif
	121	free_page((unsigned long)pte);
	122	}
	123
2f569afd	124	void pte_free(struct mm_struct *mm, pgtable_t ptepage)
1da177e4 LT	125	{
	126	#ifdef CONFIG_SMP
	127	hash_page_sync();
	128	#endif
2f569afd	129	pgtable_page_dtor(ptepage);
1da177e4 LT	130	__free_page(ptepage);
	131	}
	132
a85f6d4a	133	#ifndef CONFIG_PHYS_64BIT
1da177e4 LT	134	void __iomem *
	135	ioremap(phys_addr_t addr, unsigned long size)
	136	{
	137	return __ioremap(addr, size, _PAGE_NO_CACHE);
	138	}
a85f6d4a	139	#else /* CONFIG_PHYS_64BIT */
1da177e4 LT	140	void __iomem *
	141	ioremap64(unsigned long long addr, unsigned long size)
	142	{
	143	return __ioremap(addr, size, _PAGE_NO_CACHE);
	144	}
	145
	146	void __iomem *
	147	ioremap(phys_addr_t addr, unsigned long size)
	148	{
	149	phys_addr_t addr64 = fixup_bigphys_addr(addr, size);
	150
	151	return ioremap64(addr64, size);
	152	}
a85f6d4a	153	#endif /* CONFIG_PHYS_64BIT */
1da177e4 LT	154
	155	void __iomem *
	156	__ioremap(phys_addr_t addr, unsigned long size, unsigned long flags)
	157	{
	158	unsigned long v, i;
	159	phys_addr_t p;
	160	int err;
	161
	162	/*
	163	* Choose an address to map it to.
	164	* Once the vmalloc system is running, we use it.
	165	* Before then, we use space going down from ioremap_base
	166	* (ioremap_bot records where we're up to).
	167	*/
	168	p = addr & PAGE_MASK;
	169	size = PAGE_ALIGN(addr + size) - p;
	170
	171	/*
	172	* If the address lies within the first 16 MB, assume it's in ISA
	173	* memory space
	174	*/
	175	if (p < 1610241024)
	176	p += _ISA_MEM_BASE;
	177
	178	/*
	179	* Don't allow anybody to remap normal RAM that we're using.
	180	* mem_init() sets high_memory so only do the check after that.
	181	*/
	182	if ( mem_init_done && (p < virt_to_phys(high_memory)) )
	183	{
a85f6d4a	184	printk("__ioremap(): phys addr "PHYS_FMT" is RAM lr %p\n", p,
1da177e4 LT	185	__builtin_return_address(0));
	186	return NULL;
	187	}
	188
	189	if (size == 0)
	190	return NULL;
	191
	192	/*
	193	* Is it already mapped? Perhaps overlapped by a previous
	194	* BAT mapping. If the whole area is mapped then we're done,
	195	* otherwise remap it since we want to keep the virt addrs for
	196	* each request contiguous.
	197	*
	198	* We make the assumption here that if the bottom and top
	199	* of the range we want are mapped then it's mapped to the
	200	* same virt address (and this is contiguous).
	201	* -- Cort
	202	*/
	203	if ((v = p_mapped_by_bats(p)) /&& p_mapped_by_bats(p+size-1)/ )
	204	goto out;
	205
1da177e4 LT	206	if (mem_init_done) {
	207	struct vm_struct *area;
	208	area = get_vm_area(size, VM_IOREMAP);
	209	if (area == 0)
	210	return NULL;
	211	v = (unsigned long) area->addr;
	212	} else {
	213	v = (ioremap_bot -= size);
	214	}
	215
	216	if ((flags & _PAGE_PRESENT) == 0)
	217	flags \|= _PAGE_KERNEL;
	218	if (flags & _PAGE_NO_CACHE)
	219	flags \|= _PAGE_GUARDED;
	220
	221	/*
	222	* Should check if it is a candidate for a BAT mapping
	223	*/
	224
	225	err = 0;
	226	for (i = 0; i < size && err == 0; i += PAGE_SIZE)
	227	err = map_page(v+i, p+i, flags);
	228	if (err) {
	229	if (mem_init_done)
	230	vunmap((void *)v);
	231	return NULL;
	232	}
	233
	234	out:
	235	return (void __iomem *) (v + ((unsigned long)addr & ~PAGE_MASK));
	236	}
	237
	238	void iounmap(volatile void __iomem *addr)
	239	{
	240	/*
	241	* If mapped by BATs then there is nothing to do.
	242	* Calling vfree() generates a benign warning.
	243	*/
	244	if (v_mapped_by_bats((unsigned long)addr)) return;
	245
	246	if (addr > high_memory && (unsigned long) addr < ioremap_bot)
	247	vunmap((void *) (PAGE_MASK & (unsigned long)addr));
	248	}
	249
	250	void __iomem *ioport_map(unsigned long port, unsigned int len)
	251	{
	252	return (void __iomem *) (port + _IO_BASE);
	253	}
	254
	255	void ioport_unmap(void __iomem *addr)
	256	{
	257	/* Nothing to do */
	258	}
	259	EXPORT_SYMBOL(ioport_map);
	260	EXPORT_SYMBOL(ioport_unmap);
	261
	262	int
	263	map_page(unsigned long va, phys_addr_t pa, int flags)
	264	{
	265	pmd_t *pd;
	266	pte_t *pg;
	267	int err = -ENOMEM;
	268
1da177e4 LT	269	/* Use upper 10 bits of VA to index the first level map */
	270	pd = pmd_offset(pgd_offset_k(va), va);
	271	/* Use middle 10 bits of VA to index the second-level map */
872fec16	272	pg = pte_alloc_kernel(pd, va);
1da177e4 LT	273	if (pg != 0) {
	274	err = 0;
	275	set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT, __pgprot(flags)));
	276	if (mem_init_done)
	277	flush_HPTE(0, va, pmd_val(*pd));
	278	}
1da177e4 LT	279	return err;
	280	}
	281
	282	/*
	283	* Map in all of physical memory starting at KERNELBASE.
	284	*/
	285	void __init mapin_ram(void)
	286	{
	287	unsigned long v, p, s, f;
	288
	289	s = mmu_mapin_ram();
	290	v = KERNELBASE + s;
	291	p = PPC_MEMSTART + s;
	292	for (; s < total_lowmem; s += PAGE_SIZE) {
	293	if ((char ) v >= _stext && (char ) v < etext)
	294	f = _PAGE_RAM_TEXT;
	295	else
	296	f = _PAGE_RAM;
	297	map_page(v, p, f);
	298	v += PAGE_SIZE;
	299	p += PAGE_SIZE;
	300	}
	301	}
	302
1da177e4	303	/* is x a power of 4? */
8dabba5d	304	#define is_power_of_4(x) is_power_of_2(x) && (ffs(x) & 1)
1da177e4 LT	305
	306	/*
	307	* Set up a mapping for a block of I/O.
	308	* virt, phys, size must all be page-aligned.
	309	* This should only be called before ioremap is called.
	310	*/
	311	void __init io_block_mapping(unsigned long virt, phys_addr_t phys,
	312	unsigned int size, int flags)
	313	{
	314	int i;
	315
	316	if (virt > KERNELBASE && virt < ioremap_bot)
	317	ioremap_bot = ioremap_base = virt;
	318
	319	#ifdef HAVE_BATS
	320	/*
	321	* Use a BAT for this if possible...
	322	*/
	323	if (io_bat_index < 2 && is_power_of_2(size)
	324	&& (virt & (size - 1)) == 0 && (phys & (size - 1)) == 0) {
	325	setbat(io_bat_index, virt, phys, size, flags);
	326	++io_bat_index;
	327	return;
	328	}
	329	#endif /* HAVE_BATS */
	330
1da177e4 LT	331	/* No BATs available, put it in the page tables. */
	332	for (i = 0; i < size; i += PAGE_SIZE)
	333	map_page(virt + i, phys + i, flags);
	334	}
	335
	336	/* Scan the real Linux page tables and return a PTE pointer for
	337	* a virtual address in a context.
	338	* Returns true (1) if PTE was found, zero otherwise. The pointer to
	339	* the PTE pointer is unmodified if PTE is not found.
	340	*/
	341	int
bab70a4a	342	get_pteptr(struct mm_struct mm, unsigned long addr, pte_t ptep, pmd_t *pmdp)
1da177e4 LT	343	{
	344	pgd_t *pgd;
	345	pmd_t *pmd;
	346	pte_t *pte;
	347	int retval = 0;
	348
	349	pgd = pgd_offset(mm, addr & PAGE_MASK);
	350	if (pgd) {
	351	pmd = pmd_offset(pgd, addr & PAGE_MASK);
	352	if (pmd_present(*pmd)) {
	353	pte = pte_offset_map(pmd, addr & PAGE_MASK);
	354	if (pte) {
	355	retval = 1;
	356	*ptep = pte;
bab70a4a ES	357	if (pmdp)
bab70a4a ES	358	*pmdp = pmd;
1da177e4 LT	359	/* XXX caller needs to do pte_unmap, yuck */
	360	}
	361	}
	362	}
	363	return(retval);
	364	}
	365
	366	/* Find physical address for this virtual address. Normally used by
	367	* I/O functions, but anyone can call it.
	368	*/
	369	unsigned long iopa(unsigned long addr)
	370	{
	371	unsigned long pa;
	372
	373	/* I don't know why this won't work on PMacs or CHRP. It
	374	* appears there is some bug, or there is some implicit
	375	* mapping done not properly represented by BATs or in page
	376	* tables.......I am actively working on resolving this, but
	377	* can't hold up other stuff. -- Dan
	378	*/
	379	pte_t *pte;
	380	struct mm_struct *mm;
	381
	382	/* Check the BATs */
	383	pa = v_mapped_by_bats(addr);
	384	if (pa)
	385	return pa;
	386
	387	/* Allow mapping of user addresses (within the thread)
	388	* for DMA if necessary.
	389	*/
	390	if (addr < TASK_SIZE)
	391	mm = current->mm;
	392	else
	393	mm = &init_mm;
	394
	395	pa = 0;
bab70a4a	396	if (get_pteptr(mm, addr, &pte, NULL)) {
1da177e4 LT	397	pa = (pte_val(*pte) & PAGE_MASK) \| (addr & ~PAGE_MASK);
	398	pte_unmap(pte);
	399	}
	400
	401	return(pa);
	402	}
	403