diff options
| author | Nicolas Pitre <nico@cam.org> | 2008-09-16 13:05:53 -0400 |
|---|---|---|
| committer | Gary King <GKing@nvidia.com> | 2010-02-02 15:56:15 -0800 |
| commit | 1f62c1e9ba3e2ac33b2dfa4c7b08b7cb2fc3c81e (patch) | |
| tree | daad172d9979fd3cf6bdd98262cb4def88dcf65e /arch | |
| parent | ec1c33b802243ea87310b236bad856ddc0dfd8b3 (diff) | |
[ARM] fixmap support
This is the minimum fixmap interface expected to be implemented by
architectures supporting highmem.
We have a second level page table already allocated and covering
0xfff00000-0xffffffff because the exception vector page is located
at 0xffff0000, and various cache tricks already use some entries above
0xffff0000. Therefore the PTEs covering 0xfff00000-0xfffeffff are free
to be used.
However the XScale cache flushing code already uses virtual addresses
between 0xfffe0000 and 0xfffeffff.
So this reserves the 0xfff00000-0xfffdffff range for fixmap stuff.
The Documentation/arm/memory.txt information is updated accordingly,
including the information about the actual top of DMA memory mapping
region which didn't match the code.
Signed-off-by: Nicolas Pitre <nico@marvell.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/include/asm/fixmap.h | 41 | ||||
| -rw-r--r-- | arch/arm/mm/mm.h | 3 |
2 files changed, 42 insertions, 2 deletions
diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h new file mode 100644 index 000000000000..bbae919bceb4 --- /dev/null +++ b/arch/arm/include/asm/fixmap.h @@ -0,0 +1,41 @@ +#ifndef _ASM_FIXMAP_H +#define _ASM_FIXMAP_H + +/* + * Nothing too fancy for now. + * + * On ARM we already have well known fixed virtual addresses imposed by + * the architecture such as the vector page which is located at 0xffff0000, + * therefore a second level page table is already allocated covering + * 0xfff00000 upwards. + * + * The cache flushing code in proc-xscale.S uses the virtual area between + * 0xfffe0000 and 0xfffeffff. + */ + +#define FIXADDR_START 0xfff00000UL +#define FIXADDR_TOP 0xfffe0000UL +#define FIXADDR_SIZE (FIXADDR_TOP - FIXADDR_START) + +#define FIX_KMAP_BEGIN 0 +#define FIX_KMAP_END (FIXADDR_SIZE >> PAGE_SHIFT) + +#define __fix_to_virt(x) (FIXADDR_START + ((x) << PAGE_SHIFT)) +#define __virt_to_fix(x) (((x) - FIXADDR_START) >> PAGE_SHIFT) + +extern void __this_fixmap_does_not_exist(void); + +static inline unsigned long fix_to_virt(const unsigned int idx) +{ + if (idx >= FIX_KMAP_END) + __this_fixmap_does_not_exist(); + return __fix_to_virt(idx); +} + +static inline unsigned int virt_to_fix(const unsigned long vaddr) +{ + BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); + return __virt_to_fix(vaddr); +} + +#endif diff --git a/arch/arm/mm/mm.h b/arch/arm/mm/mm.h index 95bbe112965e..c4f6f05198e0 100644 --- a/arch/arm/mm/mm.h +++ b/arch/arm/mm/mm.h @@ -1,7 +1,6 @@ -/* the upper-most page table pointer */ - #ifdef CONFIG_MMU +/* the upper-most page table pointer */ extern pmd_t *top_pmd; #define TOP_PTE(x) pte_offset_kernel(top_pmd, x) |