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efi: Add a function to look up existing IO memory mappings

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The EFI initialization creates virtual mappings for EFI boot services
memory, so if a driver wants to access EFI boot services memory, it
cannot call ioremap itself; doing so will trip the WARN about mapping
RAM twice.  Thus, a driver accessing EFI boot services memory must do so
via the existing mapping already created during EFI intiialization.
Since the EFI code already maintains a memory map for that memory, add a
function efi_lookup_mapped_addr to look up mappings in that memory map.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Link: http://lkml.kernel.org/r/0eb48ae012797912874919110660ad420b90268b.1348876882.git.josh@joshtriplett.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Josh Triplett 2012-09-28 17:56:08 -07:00 • committed by H. Peter Anvin
parent 785107923a
commit 7bc90e01c3
2 changed files with 29 additions and 0 deletions
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1
include/linux/efi.h
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@ -501,6 +501,7 @@ extern void efi_free_boot_services(void);
#else
static inline void efi_free_boot_services(void) {}
#endif
extern void __iomem *efi_lookup_mapped_addr(u64 phys_addr);
extern u64 efi_get_iobase (void);
extern u32 efi_mem_type (unsigned long phys_addr);
extern u64 efi_mem_attributes (unsigned long phys_addr);