| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | #include <linux/config.h> |
| 19 | #undef CONFIG_X86_PAE |
| 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 | #define boot_pte_index(address) \ |
| 34 | (((address) >> PAGE_SHIFT) & (BOOT_PTE_PTRS - 1)) |
| 35 | |
| 36 | static inline boot_pte_t* boot_vaddr_to_pte(void *address) |
| 37 | { |
| 38 | boot_pte_t* boot_pg = (boot_pte_t*)pg0; |
| 39 | return &boot_pg[boot_pte_index((unsigned long)address)]; |
| 40 | } |
| 41 | |
| 42 | /* |
| 43 | * This is only for a caller who is clever enough to page-align |
| 44 | * phys_addr and virtual_source, and who also has a preference |
| 45 | * about which virtual address from which to steal ptes |
| 46 | */ |
| 47 | static void __boot_ioremap(unsigned long phys_addr, unsigned long nrpages, |
| 48 | void* virtual_source) |
| 49 | { |
| 50 | boot_pte_t* pte; |
| 51 | int i; |
| 52 | char *vaddr = virtual_source; |
| 53 | |
| 54 | pte = boot_vaddr_to_pte(virtual_source); |
| 55 | for (i=0; i < nrpages; i++, phys_addr += PAGE_SIZE, pte++) { |
| 56 | set_pte(pte, pfn_pte(phys_addr>>PAGE_SHIFT, PAGE_KERNEL)); |
| 57 | __flush_tlb_one(&vaddr[i*PAGE_SIZE]); |
| 58 | } |
| 59 | } |
| 60 | |
| 61 | /* the virtual space we're going to remap comes from this array */ |
| 62 | #define BOOT_IOREMAP_PAGES 4 |
| 63 | #define BOOT_IOREMAP_SIZE (BOOT_IOREMAP_PAGES*PAGE_SIZE) |
| 64 | static __initdata char boot_ioremap_space[BOOT_IOREMAP_SIZE] |
| 65 | __attribute__ ((aligned (PAGE_SIZE))); |
| 66 | |
| 67 | /* |
| 68 | * This only applies to things which need to ioremap before paging_init() |
| 69 | * bt_ioremap() and plain ioremap() are both useless at this point. |
| 70 | * |
| 71 | * When used, we're still using the boot-time pagetables, which only |
| 72 | * have 2 PTE pages mapping the first 8MB |
| 73 | * |
| 74 | * There is no unmap. The boot-time PTE pages aren't used after boot. |
| 75 | * If you really want the space back, just remap it yourself. |
| 76 | * boot_ioremap(&ioremap_space-PAGE_OFFSET, BOOT_IOREMAP_SIZE) |
| 77 | */ |
| 78 | __init void* boot_ioremap(unsigned long phys_addr, unsigned long size) |
| 79 | { |
| 80 | unsigned long last_addr, offset; |
| 81 | unsigned int nrpages; |
| 82 | |
| 83 | last_addr = phys_addr + size - 1; |
| 84 | |
| 85 | /* page align the requested address */ |
| 86 | offset = phys_addr & ~PAGE_MASK; |
| 87 | phys_addr &= PAGE_MASK; |
| 88 | size = PAGE_ALIGN(last_addr) - phys_addr; |
| 89 | |
| 90 | nrpages = size >> PAGE_SHIFT; |
| 91 | if (nrpages > BOOT_IOREMAP_PAGES) |
| 92 | return NULL; |
| 93 | |
| 94 | __boot_ioremap(phys_addr, nrpages, boot_ioremap_space); |
| 95 | |
| 96 | return &boot_ioremap_space[offset]; |
| 97 | } |