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/*
* arch/i386/mm/boot_ioremap.c
*
* Re-map functions for early boot-time before paging_init() when the
* boot-time pagetables are still in use
*
* Written by Dave Hansen <haveblue@us.ibm.com>
*/
/*
* We need to use the 2-level pagetable functions, but CONFIG_X86_PAE
* keeps that from happenning. If anyone has a better way, I'm listening.
*
* boot_pte_t is defined only if this all works correctly
*/
#undef CONFIG_X86_PAE
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <linux/init.h>
#include <linux/stddef.h>
/*
* I'm cheating here. It is known that the two boot PTE pages are
* allocated next to each other. I'm pretending that they're just
* one big array.
*/
#define BOOT_PTE_PTRS (PTRS_PER_PTE*2)
static unsigned long boot_pte_index(unsigned long vaddr)
{
return __pa(vaddr) >> PAGE_SHIFT;
}
static inline boot_pte_t* boot_vaddr_to_pte(void *address)
{
boot_pte_t* boot_pg = (boot_pte_t*)pg0;
return &boot_pg[boot_pte_index((unsigned long)address)];
}
/*
* This is only for a caller who is clever enough to page-align
* phys_addr and virtual_source, and who also has a preference
* about which virtual address from which to steal ptes
*/
static void __boot_ioremap(unsigned long phys_addr, unsigned long nrpages,
void* virtual_source)
{
boot_pte_t* pte;
int i;
char *vaddr = virtual_source;
pte = boot_vaddr_to_pte(virtual_source);
for (i=0; i < nrpages; i++, phys_addr += PAGE_SIZE, pte++) {
set_pte(pte, pfn_pte(phys_addr>>PAGE_SHIFT, PAGE_KERNEL));
__flush_tlb_one(&vaddr[i*PAGE_SIZE]);
}
}
/* the virtual space we're going to remap comes from this array */
#define BOOT_IOREMAP_PAGES 4
#define BOOT_IOREMAP_SIZE (BOOT_IOREMAP_PAGES*PAGE_SIZE)
static __initdata char boot_ioremap_space[BOOT_IOREMAP_SIZE]
__attribute__ ((aligned (PAGE_SIZE)));
/*
* This only applies to things which need to ioremap before paging_init()
* bt_ioremap() and plain ioremap() are both useless at this point.
*
* When used, we're still using the boot-time pagetables, which only
* have 2 PTE pages mapping the first 8MB
*
* There is no unmap. The boot-time PTE pages aren't used after boot.
* If you really want the space back, just remap it yourself.
* boot_ioremap(&ioremap_space-PAGE_OFFSET, BOOT_IOREMAP_SIZE)
*/
__init void* boot_ioremap(unsigned long phys_addr, unsigned long size)
{
unsigned long last_addr, offset;
unsigned int nrpages;
last_addr = phys_addr + size - 1;
/* page align the requested address */
offset = phys_addr & ~PAGE_MASK;
phys_addr &= PAGE_MASK;
size = PAGE_ALIGN(last_addr) - phys_addr;
nrpages = size >> PAGE_SHIFT;
if (nrpages > BOOT_IOREMAP_PAGES)
return NULL;
__boot_ioremap(phys_addr, nrpages, boot_ioremap_space);
return &boot_ioremap_space[offset];
}
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