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authorHaavard Skinnemoen <haavard.skinnemoen@atmel.com>2010-08-12 13:52:54 +0700
committerReinhard Meyer <u-boot@emk-elektronik.de>2010-09-03 15:13:02 +0200
commit1f36f73fe70560a2bd286a7abc8530fdc93af9ae (patch)
tree23ba61ced5254af43107e7d0de5b25b566ac78bb /arch/avr32/cpu/start.S
parent9cec2fc209a000655af77256a39ede7c7d441e56 (diff)
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avr32: Add simple paging support
Use the MMU hardware to set up 1:1 mappings between physical and virtual addresses. This allows us to bypass the cache when accessing the flash without having to do any physical-to-virtual address mapping in the CFI driver. The virtual memory mappings are defined at compile time through a sorted array of virtual memory range objects. When a TLB miss exception happens, the exception handler does a binary search through the array until it finds a matching entry and loads it into the TLB. The u-boot image itself is covered by a fixed TLB entry which is never replaced. This makes the 'saveenv' command work again on ATNGW100 and other boards using the CFI driver, hopefully without breaking any rules. Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Diffstat (limited to 'arch/avr32/cpu/start.S')
-rw-r--r--arch/avr32/cpu/start.S19
1 files changed, 13 insertions, 6 deletions
diff --git a/arch/avr32/cpu/start.S b/arch/avr32/cpu/start.S
index 99c9e06..06bf4c6 100644
--- a/arch/avr32/cpu/start.S
+++ b/arch/avr32/cpu/start.S
@@ -82,12 +82,19 @@ _evba:
.org 0x44
rjmp unknown_exception /* DTLB Modified */
- .org 0x50
- rjmp unknown_exception /* ITLB Miss */
- .org 0x60
- rjmp unknown_exception /* DTLB Miss (read) */
- .org 0x70
- rjmp unknown_exception /* DTLB Miss (write) */
+ .org 0x50 /* ITLB Miss */
+ pushm r8-r12,lr
+ rjmp 1f
+ .org 0x60 /* DTLB Miss (read) */
+ pushm r8-r12,lr
+ rjmp 1f
+ .org 0x70 /* DTLB Miss (write) */
+ pushm r8-r12,lr
+1: mov r12, sp
+ rcall mmu_handle_tlb_miss
+ popm r8-r12,lr
+ brne unknown_exception
+ rete
.size _evba, . - _evba