LXR linux/arch/i386/mm/boot

   1/*
   2 * arch/i386/mm/boot_ioremap.c
   3 * 
   4 * Re-map functions for early boot-time before paging_init() when the 
   5 * boot-time pagetables are still in use
   6 *
   7 * Written by Dave Hansen <haveblue@us.ibm.com>
   8 */
   9
  10
  11/*
  12 * We need to use the 2-level pagetable functions, but CONFIG_X86_PAE
  13 * keeps that from happenning.  If anyone has a better way, I'm listening.
  14 *
  15 * boot_pte_t is defined only if this all works correctly
  16 */
  17
  18#undef CONFIG_X86_PAE
  19#undef CONFIG_PARAVIRT
  20#include <asm/page.h>
  21#include <asm/pgtable.h>
  22#include <asm/tlbflush.h>
  23#include <linux/init.h>
  24#include <linux/stddef.h>
  25
  26/* 
  27 * I'm cheating here.  It is known that the two boot PTE pages are 
  28 * allocated next to each other.  I'm pretending that they're just
  29 * one big array. 
  30 */
  31
  32#define BOOT_PTE_PTRS (PTRS_PER_PTE*2)
  33
  34static unsigned long boot_pte_index(unsigned long vaddr) 
  35{
  36        return __pa(vaddr) >> PAGE_SHIFT;
  37}
  38
  39static inline boot_pte_t* boot_vaddr_to_pte(void *address)
  40{
  41        boot_pte_t* boot_pg = (boot_pte_t*)pg0;
  42        return &boot_pg[boot_pte_index((unsigned long)address)];
  43}
  44
  45/*
  46 * This is only for a caller who is clever enough to page-align
  47 * phys_addr and virtual_source, and who also has a preference
  48 * about which virtual address from which to steal ptes
  49 */
  50static void __boot_ioremap(unsigned long phys_addr, unsigned long nrpages, 
  51                    void* virtual_source)
  52{
  53        boot_pte_t* pte;
  54        int i;
  55        char *vaddr = virtual_source;
  56
  57        pte = boot_vaddr_to_pte(virtual_source);
  58        for (i=0; i < nrpages; i++, phys_addr += PAGE_SIZE, pte++) {
  59                set_pte(pte, pfn_pte(phys_addr>>PAGE_SHIFT, PAGE_KERNEL));
  60                __flush_tlb_one(&vaddr[i*PAGE_SIZE]);
  61        }
  62}
  63
  64/* the virtual space we're going to remap comes from this array */
  65#define BOOT_IOREMAP_PAGES 4
  66#define BOOT_IOREMAP_SIZE (BOOT_IOREMAP_PAGES*PAGE_SIZE)
  67static __initdata char boot_ioremap_space[BOOT_IOREMAP_SIZE]
  68                       __attribute__ ((aligned (PAGE_SIZE)));
  69
  70/*
  71 * This only applies to things which need to ioremap before paging_init()
  72 * bt_ioremap() and plain ioremap() are both useless at this point.
  73 * 
  74 * When used, we're still using the boot-time pagetables, which only
  75 * have 2 PTE pages mapping the first 8MB
  76 *
  77 * There is no unmap.  The boot-time PTE pages aren't used after boot.
  78 * If you really want the space back, just remap it yourself.
  79 * boot_ioremap(&ioremap_space-PAGE_OFFSET, BOOT_IOREMAP_SIZE)
  80 */
  81__init void* boot_ioremap(unsigned long phys_addr, unsigned long size)
  82{
  83        unsigned long last_addr, offset;
  84        unsigned int nrpages;
  85        
  86        last_addr = phys_addr + size - 1;
  87
  88        /* page align the requested address */
  89        offset = phys_addr & ~PAGE_MASK;
  90        phys_addr &= PAGE_MASK;
  91        size = PAGE_ALIGN(last_addr) - phys_addr;
  92        
  93        nrpages = size >> PAGE_SHIFT;
  94        if (nrpages > BOOT_IOREMAP_PAGES)
  95                return NULL;
  96        
  97        __boot_ioremap(phys_addr, nrpages, boot_ioremap_space);
  98
  99        return &boot_ioremap_space[offset];
 100}
 101