From c0466d46b7ea511f102eb6e57da59d95bf4ef95f Mon Sep 17 00:00:00 2001 From: "Ronald G. Minnich" Date: Tue, 30 Apr 2013 10:11:30 -0700 Subject: [PATCH] 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 Reviewed-on: http://review.coreboot.org/3160 Reviewed-by: Paul Menzel Tested-by: build bot (Jenkins) Reviewed-by: David Hendricks --- src/arch/armv7/include/arch/cache.h | 2 ++ src/arch/armv7/lib/mmu.c | 13 +++++++++++++ 2 files changed, 15 insertions(+) diff --git a/src/arch/armv7/include/arch/cache.h b/src/arch/armv7/include/arch/cache.h index 028cf1808d..d5c3a5b241 100644 --- a/src/arch/armv7/include/arch/cache.h +++ b/src/arch/armv7/include/arch/cache.h @@ -303,6 +303,8 @@ 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 224b566a50..82c735818e 100644 --- a/src/arch/armv7/lib/mmu.c +++ b/src/arch/armv7/lib/mmu.c @@ -39,6 +39,19 @@ 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; + tlbimvaa(i); + } +} + void mmu_config_range(unsigned long start_mb, unsigned long size_mb, enum dcache_policy policy) {