timestamp: Remove HAS_PRECBMEM_TIMESTAMP_REGION Kconfig

This patch generalizes the approach previously used for ARM32
TTB_SUBTABLES to "auto-detect" whether a certain region was defined in
memlayout.ld. This allows us to get rid of the explicit Kconfig for the
TIMESTAMP region, reducing configuration redundancy and avoiding
confusion when setting up future boards.

(Removing armv4/bootblock_simple.c because it references this Kconfig
and it is a dead file that I just forgot to remove in CL:12076.)

BRANCH=None
BUG=None
TEST=Booted Oak and confirmed that all pre-RAM timestamps are still
there. Built Nyan and Falco.

Change-Id: I557a4b263018511d17baa4177963130a97ea310a
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/13652
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

1 files changed, 2 insertions, 5 deletions

diff --git a/src/arch/arm/armv7/mmu.c b/src/arch/arm/armv7/mmu.c
index 8c2f78c4d0..2cf90e75f7 100644
--- a/src/arch/arm/armv7/mmu.c
+++ b/src/arch/arm/armv7/mmu.c
@@ -118,11 +118,8 @@ typedef uint32_t pte_t;
 
 static pte_t *const ttb_buff = (void *)_ttb;
 
-/* Not all boards want to use subtables and declare them in memlayout.ld. This
- * outputs two 0x00000000 symbols if they don't, making _ttb_subtables_size 0.
- * (I would like to explicitly assign them to 0 here, but that triggers
- * https://sourceware.org/bugzilla/show_bug.cgi?id=1038 in GNU as.) */
-asm (".weak _ttb_subtables, _ettb_subtables");
+/* Not all boards want to use subtables and declare them in memlayout.ld. */
+DECLARE_OPTIONAL_REGION(ttb_subtables);
 
 static struct {
 	pte_t value;