arm: Add control over cachability of memory regions

Add support for adjusting the L1 cache behavior by updating the MMU
configuration. The mmu_set_region_dcache_behaviour() function allows
drivers to make these changes after the MMU is set up.

It is implemented only for ARMv7 at present.

This is needed for LCD support, where we want to make the LCD frame buffer
write-through (or off) rather than write-back.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
index 2b28a261b..78ca8e0a6 100644
--- a/arch/arm/include/asm/system.h
+++ b/arch/arm/include/asm/system.h
@@ -75,6 +75,37 @@ static inline void set_cr(unsigned int val)
 	isb();
 }
 
+/* options available for data cache on each page */
+enum dcache_option {
+	DCACHE_OFF = 0x12,
+	DCACHE_WRITETHROUGH = 0x1a,
+	DCACHE_WRITEBACK = 0x1e,
+};
+
+/* Size of an MMU section */
+enum {
+	MMU_SECTION_SHIFT	= 20,
+	MMU_SECTION_SIZE	= 1 << MMU_SECTION_SHIFT,
+};
+
+/**
+ * Change the cache settings for a region.
+ *
+ * \param start		start address of memory region to change
+ * \param size		size of memory region to change
+ * \param option	dcache option to select
+ */
+void mmu_set_region_dcache_behaviour(u32 start, int size,
+				     enum dcache_option option);
+
+/**
+ * Register an update to the page tables, and flush the TLB
+ *
+ * \param start		start address of update in page table
+ * \param stop		stop address of update in page table
+ */
+void mmu_page_table_flush(unsigned long start, unsigned long stop);
+
 #endif /* __ASSEMBLY__ */
 
 #define arch_align_stack(x) (x)