2 * arch/i386/mm/boot_ioremap.c
4 * Re-map functions for early boot-time before paging_init() when the
5 * boot-time pagetables are still in use
7 * Written by Dave Hansen <haveblue@us.ibm.com>
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.
15 * boot_pte_t is defined only if this all works correctly
20 #include <asm/pgtable.h>
21 #include <asm/tlbflush.h>
22 #include <linux/init.h>
23 #include <linux/stddef.h>
26 * I'm cheating here. It is known that the two boot PTE pages are
27 * allocated next to each other. I'm pretending that they're just
31 #define BOOT_PTE_PTRS (PTRS_PER_PTE*2)
32 #define boot_pte_index(address) \
33 (((address) >> PAGE_SHIFT) & (BOOT_PTE_PTRS - 1))
35 static inline boot_pte_t
* boot_vaddr_to_pte(void *address
)
37 boot_pte_t
* boot_pg
= (boot_pte_t
*)pg0
;
38 return &boot_pg
[boot_pte_index((unsigned long)address
)];
42 * This is only for a caller who is clever enough to page-align
43 * phys_addr and virtual_source, and who also has a preference
44 * about which virtual address from which to steal ptes
46 static void __boot_ioremap(unsigned long phys_addr
, unsigned long nrpages
,
51 char *vaddr
= virtual_source
;
53 pte
= boot_vaddr_to_pte(virtual_source
);
54 for (i
=0; i
< nrpages
; i
++, phys_addr
+= PAGE_SIZE
, pte
++) {
55 set_pte(pte
, pfn_pte(phys_addr
>>PAGE_SHIFT
, PAGE_KERNEL
));
56 __flush_tlb_one(&vaddr
[i
*PAGE_SIZE
]);
60 /* the virtual space we're going to remap comes from this array */
61 #define BOOT_IOREMAP_PAGES 4
62 #define BOOT_IOREMAP_SIZE (BOOT_IOREMAP_PAGES*PAGE_SIZE)
63 static __initdata
char boot_ioremap_space
[BOOT_IOREMAP_SIZE
]
64 __attribute__ ((aligned (PAGE_SIZE
)));
67 * This only applies to things which need to ioremap before paging_init()
68 * bt_ioremap() and plain ioremap() are both useless at this point.
70 * When used, we're still using the boot-time pagetables, which only
71 * have 2 PTE pages mapping the first 8MB
73 * There is no unmap. The boot-time PTE pages aren't used after boot.
74 * If you really want the space back, just remap it yourself.
75 * boot_ioremap(&ioremap_space-PAGE_OFFSET, BOOT_IOREMAP_SIZE)
77 __init
void* boot_ioremap(unsigned long phys_addr
, unsigned long size
)
79 unsigned long last_addr
, offset
;
82 last_addr
= phys_addr
+ size
- 1;
84 /* page align the requested address */
85 offset
= phys_addr
& ~PAGE_MASK
;
86 phys_addr
&= PAGE_MASK
;
87 size
= PAGE_ALIGN(last_addr
) - phys_addr
;
89 nrpages
= size
>> PAGE_SHIFT
;
90 if (nrpages
> BOOT_IOREMAP_PAGES
)
93 __boot_ioremap(phys_addr
, nrpages
, boot_ioremap_space
);
95 return &boot_ioremap_space
[offset
];