diff options
| author | Haavard Skinnemoen <haavard.skinnemoen@atmel.com> | 2010-08-12 13:52:54 +0700 |
|---|---|---|
| committer | Reinhard Meyer <u-boot@emk-elektronik.de> | 2010-09-03 15:13:02 +0200 |
| commit | 1f36f73fe70560a2bd286a7abc8530fdc93af9ae (patch) | |
| tree | 23ba61ced5254af43107e7d0de5b25b566ac78bb /arch/avr32/cpu/start.S | |
| parent | 9cec2fc209a000655af77256a39ede7c7d441e56 (diff) | |
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.S | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/arch/avr32/cpu/start.S b/arch/avr32/cpu/start.S index 99c9e06cb8..06bf4c692d 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 |