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/*
* 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.)
*
* DC21285 currently has a bug in that the PCI address extension
* register affects the address of any writes waiting in the outbound
* FIFO. Unfortunately, it is not possible to tell the DC21285 to
* flush this - flushing the area causes the bus to lock.
*/
#include <linux/vmalloc.h>
#include <asm/io.h>
static inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
unsigned long phys_addr, pgprot_t pgprot)
{
unsigned long end;
address &= ~PMD_MASK;
end = address + size;
if (end > PMD_SIZE)
end = PMD_SIZE;
do {
if (!pte_none(*pte))
printk("remap_area_pte: page already exists\n");
set_pte(pte, mk_pte_phys(phys_addr, pgprot));
address += PAGE_SIZE;
phys_addr += PAGE_SIZE;
pte++;
} while (address < end);
}
static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
unsigned long phys_addr, unsigned long flags)
{
unsigned long end;
pgprot_t pgprot;
address &= ~PGDIR_MASK;
end = address + size;
if (end > PGDIR_SIZE)
end = PGDIR_SIZE;
phys_addr -= address;
pgprot = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY | L_PTE_WRITE | flags);
do {
pte_t * pte = pte_alloc_kernel(pmd, address);
if (!pte)
return -ENOMEM;
remap_area_pte(pte, address, end - address, address + phys_addr, pgprot);
address = (address + PMD_SIZE) & PMD_MASK;
pmd++;
} while (address < end);
return 0;
}
static int remap_area_pages(unsigned long address, unsigned long phys_addr,
unsigned long size, unsigned long flags)
{
pgd_t * dir;
unsigned long end = address + size;
phys_addr -= address;
dir = pgd_offset(&init_mm, address);
flush_cache_all();
while (address < end) {
pmd_t *pmd = pmd_alloc_kernel(dir, address);
if (!pmd)
return -ENOMEM;
if (remap_area_pmd(pmd, address, end - address,
phys_addr + address, flags))
return -ENOMEM;
set_pgdir(address, *dir);
address = (address + PGDIR_SIZE) & PGDIR_MASK;
dir++;
}
flush_tlb_all();
return 0;
}
/*
* 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 include/asm-arm/proc-armv/pgtable.h for more information.
*/
void * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
{
void * addr;
struct vm_struct * area;
unsigned long offset;
/*
* Mappings have to be page-aligned
*/
offset = phys_addr & ~PAGE_MASK;
size = PAGE_ALIGN(size + offset);
/*
* Don't allow mappings that wrap..
*/
if (!size || size > phys_addr + size)
return NULL;
/*
* Ok, go for it..
*/
area = get_vm_area(size);
if (!area)
return NULL;
addr = area->addr;
if (remap_area_pages(VMALLOC_VMADDR(addr), phys_addr, size, flags)) {
vfree(addr);
return NULL;
}
return (void *) (offset + (char *)addr);
}
void iounmap(void *addr)
{
return vfree((void *) (PAGE_MASK & (unsigned long) addr));
}
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