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>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/avr32/lib/board.c b/arch/avr32/lib/board.c
index 9e741d22e2..aa589bb4b0 100644
--- a/arch/avr32/lib/board.c
+++ b/arch/avr32/lib/board.c
@@ -33,6 +33,7 @@
 
 #include <asm/initcalls.h>
 #include <asm/sections.h>
+#include <asm/arch/mmu.h>
 
 #ifndef CONFIG_IDENT_STRING
 #define CONFIG_IDENT_STRING ""
@@ -265,6 +266,9 @@ void board_init_r(gd_t *new_gd, ulong dest_addr)
 	gd->flags |= GD_FLG_RELOC;
 	gd->reloc_off = dest_addr - CONFIG_SYS_MONITOR_BASE;
 
+	/* Enable the MMU so that we can keep u-boot simple */
+	mmu_init_r(dest_addr);
+
 	board_early_init_r();
 
 	monitor_flash_len = _edata - _text;