sh: Add fixed ioremap support

Some devices need to be ioremap'd and accessed very early in the boot
process. It is not possible to use the standard ioremap() function in
this case because that requires kmalloc()'ing some virtual address space
and kmalloc() may not be available so early in boot.

This patch provides fixmap mappings that allow physical address ranges
to be remapped into the kernel address space during the early boot
stages.

Signed-off-by: Matt Fleming <matt@console-pimps.org>
This commit is contained in:
Matt Fleming 2009-11-05 07:54:17 +00:00
parent 07cad4dc1b
commit 4d35b93a66
6 changed files with 167 additions and 3 deletions

View file

@ -60,6 +60,14 @@ enum fixed_addresses {
FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
#endif
/*
* FIX_IOREMAP entries are useful for mapping physical address
* space before ioremap() is useable, e.g. really early in boot
* before kmalloc() is working.
*/
#define FIX_N_IOREMAPS 32
FIX_IOREMAP_BEGIN,
FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS,
__end_of_fixed_addresses
};