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