arm64: Add mmu context save/restore APIs

New API required by sdm845 DDR init/training protocol

TEST=build & run

Change-Id: I8442442c0588dd6fb5e461b399e48a761f7bbf29
Signed-off-by: T Michael Turney <mturney@codeaurora.org>
Reviewed-on: https://review.coreboot.org/25818
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/src/arch/arm64/armv8/mmu.c b/src/arch/arm64/armv8/mmu.c
index a24e7c6fdd..48f77ace83 100644
--- a/src/arch/arm64/armv8/mmu.c
+++ b/src/arch/arm64/armv8/mmu.c
@@ -274,6 +274,40 @@ void mmu_init(void)
 			  TCR_TBI_USED);
 }
 
+/* Func : mmu_save_context
+ * Desc : Save mmu context (registers and ttbr base).
+ */
+void mmu_save_context(struct mmu_context *mmu_context)
+{
+	assert(mmu_context);
+
+	/* Back-up MAIR_ATTRIBUTES */
+	mmu_context->mair = raw_read_mair_el3();
+
+	/* Back-up TCR value */
+	mmu_context->tcr = raw_read_tcr_el3();
+}
+
+/* Func : mmu_restore_context
+ * Desc : Restore mmu context using input backed-up context
+ */
+void mmu_restore_context(const struct mmu_context *mmu_context)
+{
+	assert(mmu_context);
+
+	/* Restore TTBR */
+	raw_write_ttbr0_el3((uintptr_t)_ttb);
+
+	/* Restore MAIR indices */
+	raw_write_mair_el3(mmu_context->mair);
+
+	/* Restore TCR flags */
+	raw_write_tcr_el3(mmu_context->tcr);
+
+	/* invalidate tlb since ttbr is updated. */
+	tlb_invalidate_all();
+}
+
 void mmu_enable(void)
 {
 	if (((get_pte(_ttb) >> BLOCK_INDEX_SHIFT) & BLOCK_INDEX_MASK)