Ronald G. Minnich (rminnich@gmail.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/3160 -gerrit commit 32a3d97b1f0357e33977f65ce719fa0e27a8de83 Author: Ronald G. Minnich <rminnich@gmail.com> Date: Tue Apr 30 10:11:30 2013 -0700 ARMV7: add a function to disable MMU entries It is useful to be able to lock out certain address ranges, NULL being the most important example. void mmu_disable_range(unsigned long start_mb, unsigned long size_mb) Will allow us to lock out selected virtual addresses on MiB boundaries. As in other ARM mmu functions, the addresses and quantities are in units of MiB. Change-Id: If516ce955ee2d12c5a409f25acbb5a4b424f699b Signed-off-by: Ronald G. Minnich <rminnich@gmail.com> --- src/arch/armv7/include/arch/cache.h | 2 ++ src/arch/armv7/lib/mmu.c | 14 ++++++++++++++ 2 files changed, 16 insertions(+) diff --git a/src/arch/armv7/include/arch/cache.h b/src/arch/armv7/include/arch/cache.h index 1db86dc..df335a0 100644 --- a/src/arch/armv7/include/arch/cache.h +++ b/src/arch/armv7/include/arch/cache.h @@ -297,6 +297,8 @@ enum dcache_policy { DCACHE_WRITETHROUGH, }; +/* disable the mmu for a range. Primarily useful to lock out address 0. */ +void mmu_disable_range(unsigned long start_mb, unsigned long size_mb); /* mmu range configuration (set dcache policy) */ void mmu_config_range(unsigned long start_mb, unsigned long size_mb, enum dcache_policy policy); diff --git a/src/arch/armv7/lib/mmu.c b/src/arch/armv7/lib/mmu.c index 224b566..9d61c56 100644 --- a/src/arch/armv7/lib/mmu.c +++ b/src/arch/armv7/lib/mmu.c @@ -39,6 +39,20 @@ static uintptr_t ttb_addr; +void mmu_disable_range(unsigned long start_mb, unsigned long size_mb) +{ + unsigned int i; + uint32_t *ttb_entry = (uint32_t *)ttb_addr; + printk(BIOS_DEBUG, "Disabling: 0x%08lx:0x%08lx\n", + start_mb << 20, ((start_mb + size_mb) << 20) - 1); + + for (i = start_mb; i < start_mb + size_mb; i++) + ttb_entry[i] = 0; + + /* TODO: add helper to invalidate TLB by MVA */ + tlb_invalidate_all(); +} + void mmu_config_range(unsigned long start_mb, unsigned long size_mb, enum dcache_policy policy) {