https://github.com/torvalds/linux
Tip revision: 22763c5cf3690a681551162c15d34d935308c8d7 authored by Linus Torvalds on 03 December 2009, 03:51:21 UTC
Linux 2.6.32
Linux 2.6.32
Tip revision: 22763c5
ioremap.c
/*
* linux/arch/arm/mm/ioremap.c
*
* Re-map IO memory to kernel address space so that we can access it.
*
* (C) Copyright 1995 1996 Linus Torvalds
*
* Hacked for ARM by Phil Blundell <philb@gnu.org>
* Hacked to allow all architectures to build, and various cleanups
* by Russell King
*
* This allows a driver to remap an arbitrary region of bus memory into
* virtual space. One should *only* use readl, writel, memcpy_toio and
* so on with such remapped areas.
*
* Because the ARM only has a 32-bit address space we can't address the
* whole of the (physical) PCI space at once. PCI huge-mode addressing
* allows us to circumvent this restriction by splitting PCI space into
* two 2GB chunks and mapping only one at a time into processor memory.
* We use MMU protection domains to trap any attempt to access the bank
* that is not currently mapped. (This isn't fully implemented yet.)
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/io.h>
#include <asm/cputype.h>
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/sizes.h>
#include <asm/mach/map.h>
#include "mm.h"
/*
* Used by ioremap() and iounmap() code to mark (super)section-mapped
* I/O regions in vm_struct->flags field.
*/
#define VM_ARM_SECTION_MAPPING 0x80000000
static int remap_area_pte(pmd_t *pmd, unsigned long addr, unsigned long end,
unsigned long phys_addr, const struct mem_type *type)
{
pgprot_t prot = __pgprot(type->prot_pte);
pte_t *pte;
pte = pte_alloc_kernel(pmd, addr);
if (!pte)
return -ENOMEM;
do {
if (!pte_none(*pte))
goto bad;
set_pte_ext(pte, pfn_pte(phys_addr >> PAGE_SHIFT, prot), 0);
phys_addr += PAGE_SIZE;
} while (pte++, addr += PAGE_SIZE, addr != end);
return 0;
bad:
printk(KERN_CRIT "remap_area_pte: page already exists\n");
BUG();
}
static inline int remap_area_pmd(pgd_t *pgd, unsigned long addr,
unsigned long end, unsigned long phys_addr,
const struct mem_type *type)
{
unsigned long next;
pmd_t *pmd;
int ret = 0;
pmd = pmd_alloc(&init_mm, pgd, addr);
if (!pmd)
return -ENOMEM;
do {
next = pmd_addr_end(addr, end);
ret = remap_area_pte(pmd, addr, next, phys_addr, type);
if (ret)
return ret;
phys_addr += next - addr;
} while (pmd++, addr = next, addr != end);
return ret;
}
static int remap_area_pages(unsigned long start, unsigned long pfn,
size_t size, const struct mem_type *type)
{
unsigned long addr = start;
unsigned long next, end = start + size;
unsigned long phys_addr = __pfn_to_phys(pfn);
pgd_t *pgd;
int err = 0;
BUG_ON(addr >= end);
pgd = pgd_offset_k(addr);
do {
next = pgd_addr_end(addr, end);
err = remap_area_pmd(pgd, addr, next, phys_addr, type);
if (err)
break;
phys_addr += next - addr;
} while (pgd++, addr = next, addr != end);
return err;
}
int ioremap_page(unsigned long virt, unsigned long phys,
const struct mem_type *mtype)
{
return remap_area_pages(virt, __phys_to_pfn(phys), PAGE_SIZE, mtype);
}
EXPORT_SYMBOL(ioremap_page);
void __check_kvm_seq(struct mm_struct *mm)
{
unsigned int seq;
do {
seq = init_mm.context.kvm_seq;
memcpy(pgd_offset(mm, VMALLOC_START),
pgd_offset_k(VMALLOC_START),
sizeof(pgd_t) * (pgd_index(VMALLOC_END) -
pgd_index(VMALLOC_START)));
mm->context.kvm_seq = seq;
} while (seq != init_mm.context.kvm_seq);
}
#ifndef CONFIG_SMP
/*
* Section support is unsafe on SMP - If you iounmap and ioremap a region,
* the other CPUs will not see this change until their next context switch.
* Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
* which requires the new ioremap'd region to be referenced, the CPU will
* reference the _old_ region.
*
* Note that get_vm_area() allocates a guard 4K page, so we need to mask
* the size back to 1MB aligned or we will overflow in the loop below.
*/
static void unmap_area_sections(unsigned long virt, unsigned long size)
{
unsigned long addr = virt, end = virt + (size & ~(SZ_1M - 1));
pgd_t *pgd;
flush_cache_vunmap(addr, end);
pgd = pgd_offset_k(addr);
do {
pmd_t pmd, *pmdp = pmd_offset(pgd, addr);
pmd = *pmdp;
if (!pmd_none(pmd)) {
/*
* Clear the PMD from the page table, and
* increment the kvm sequence so others
* notice this change.
*
* Note: this is still racy on SMP machines.
*/
pmd_clear(pmdp);
init_mm.context.kvm_seq++;
/*
* Free the page table, if there was one.
*/
if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
pte_free_kernel(&init_mm, pmd_page_vaddr(pmd));
}
addr += PGDIR_SIZE;
pgd++;
} while (addr < end);
/*
* Ensure that the active_mm is up to date - we want to
* catch any use-after-iounmap cases.
*/
if (current->active_mm->context.kvm_seq != init_mm.context.kvm_seq)
__check_kvm_seq(current->active_mm);
flush_tlb_kernel_range(virt, end);
}
static int
remap_area_sections(unsigned long virt, unsigned long pfn,
size_t size, const struct mem_type *type)
{
unsigned long addr = virt, end = virt + size;
pgd_t *pgd;
/*
* Remove and free any PTE-based mapping, and
* sync the current kernel mapping.
*/
unmap_area_sections(virt, size);
pgd = pgd_offset_k(addr);
do {
pmd_t *pmd = pmd_offset(pgd, addr);
pmd[0] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
pfn += SZ_1M >> PAGE_SHIFT;
pmd[1] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
pfn += SZ_1M >> PAGE_SHIFT;
flush_pmd_entry(pmd);
addr += PGDIR_SIZE;
pgd++;
} while (addr < end);
return 0;
}
static int
remap_area_supersections(unsigned long virt, unsigned long pfn,
size_t size, const struct mem_type *type)
{
unsigned long addr = virt, end = virt + size;
pgd_t *pgd;
/*
* Remove and free any PTE-based mapping, and
* sync the current kernel mapping.
*/
unmap_area_sections(virt, size);
pgd = pgd_offset_k(virt);
do {
unsigned long super_pmd_val, i;
super_pmd_val = __pfn_to_phys(pfn) | type->prot_sect |
PMD_SECT_SUPER;
super_pmd_val |= ((pfn >> (32 - PAGE_SHIFT)) & 0xf) << 20;
for (i = 0; i < 8; i++) {
pmd_t *pmd = pmd_offset(pgd, addr);
pmd[0] = __pmd(super_pmd_val);
pmd[1] = __pmd(super_pmd_val);
flush_pmd_entry(pmd);
addr += PGDIR_SIZE;
pgd++;
}
pfn += SUPERSECTION_SIZE >> PAGE_SHIFT;
} while (addr < end);
return 0;
}
#endif
/*
* Remap an arbitrary physical address space into the kernel virtual
* address space. Needed when the kernel wants to access high addresses
* directly.
*
* NOTE! We need to allow non-page-aligned mappings too: we will obviously
* have to convert them into an offset in a page-aligned mapping, but the
* caller shouldn't need to know that small detail.
*
* 'flags' are the extra L_PTE_ flags that you want to specify for this
* mapping. See <asm/pgtable.h> for more information.
*/
void __iomem *
__arm_ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
unsigned int mtype)
{
const struct mem_type *type;
int err;
unsigned long addr;
struct vm_struct * area;
/*
* High mappings must be supersection aligned
*/
if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SUPERSECTION_MASK))
return NULL;
type = get_mem_type(mtype);
if (!type)
return NULL;
/*
* Page align the mapping size, taking account of any offset.
*/
size = PAGE_ALIGN(offset + size);
area = get_vm_area(size, VM_IOREMAP);
if (!area)
return NULL;
addr = (unsigned long)area->addr;
#ifndef CONFIG_SMP
if (DOMAIN_IO == 0 &&
(((cpu_architecture() >= CPU_ARCH_ARMv6) && (get_cr() & CR_XP)) ||
cpu_is_xsc3()) && pfn >= 0x100000 &&
!((__pfn_to_phys(pfn) | size | addr) & ~SUPERSECTION_MASK)) {
area->flags |= VM_ARM_SECTION_MAPPING;
err = remap_area_supersections(addr, pfn, size, type);
} else if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
area->flags |= VM_ARM_SECTION_MAPPING;
err = remap_area_sections(addr, pfn, size, type);
} else
#endif
err = remap_area_pages(addr, pfn, size, type);
if (err) {
vunmap((void *)addr);
return NULL;
}
flush_cache_vmap(addr, addr + size);
return (void __iomem *) (offset + addr);
}
EXPORT_SYMBOL(__arm_ioremap_pfn);
void __iomem *
__arm_ioremap(unsigned long phys_addr, size_t size, unsigned int mtype)
{
unsigned long last_addr;
unsigned long offset = phys_addr & ~PAGE_MASK;
unsigned long pfn = __phys_to_pfn(phys_addr);
/*
* Don't allow wraparound or zero size
*/
last_addr = phys_addr + size - 1;
if (!size || last_addr < phys_addr)
return NULL;
return __arm_ioremap_pfn(pfn, offset, size, mtype);
}
EXPORT_SYMBOL(__arm_ioremap);
void __iounmap(volatile void __iomem *io_addr)
{
void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
#ifndef CONFIG_SMP
struct vm_struct **p, *tmp;
/*
* If this is a section based mapping we need to handle it
* specially as the VM subsystem does not know how to handle
* such a beast. We need the lock here b/c we need to clear
* all the mappings before the area can be reclaimed
* by someone else.
*/
write_lock(&vmlist_lock);
for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
if ((tmp->flags & VM_IOREMAP) && (tmp->addr == addr)) {
if (tmp->flags & VM_ARM_SECTION_MAPPING) {
unmap_area_sections((unsigned long)tmp->addr,
tmp->size);
}
break;
}
}
write_unlock(&vmlist_lock);
#endif
vunmap(addr);
}
EXPORT_SYMBOL(__iounmap);