[PATCH v2 13/15] ARM: ARM64: implement dma_alloc_writecombine()

[Sascha Hauer <s.hauer@pengutronix.de>]

We currently only have dma_alloc_writecombine() for aarch32. Implement
it for aarch64 as it is useful for mapping framebuffer memory.

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 arch/arm/cpu/mmu_64.c | 11 ++++++++++-
 arch/arm/cpu/mmu_64.h | 15 ++++++---------
 2 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/arch/arm/cpu/mmu_64.c b/arch/arm/cpu/mmu_64.c
index 7c7834201b..7854f71f4c 100644
--- a/arch/arm/cpu/mmu_64.c
+++ b/arch/arm/cpu/mmu_64.c
@@ -24,6 +24,8 @@
 
 #include "mmu_64.h"
 
+#define ARCH_MAP_WRITECOMBINE  ((unsigned)-1)
+
 static uint64_t *get_ttb(void)
 {
 	return (uint64_t *)get_ttbr(current_el());
@@ -172,9 +174,11 @@ static unsigned long get_pte_attrs(unsigned flags)
 	case MAP_CACHED:
 		return CACHED_MEM;
 	case MAP_UNCACHED:
-		return attrs_uncached_mem();
+		return attrs_xn() | UNCACHED_MEM;
 	case MAP_FAULT:
 		return 0x0;
+	case ARCH_MAP_WRITECOMBINE:
+		return attrs_xn() | MEM_ALLOC_WRITECOMBINE;
 	default:
 		return ~0UL;
 	}
@@ -295,6 +299,11 @@ void dma_flush_range(void *ptr, size_t size)
 	v8_flush_dcache_range(start, end);
 }
 
+void *dma_alloc_writecombine(size_t size, dma_addr_t *dma_handle)
+{
+	return dma_alloc_map(size, dma_handle, ARCH_MAP_WRITECOMBINE);
+}
+
 static void init_range(size_t total_level0_tables)
 {
 	uint64_t *ttb = get_ttb();
diff --git a/arch/arm/cpu/mmu_64.h b/arch/arm/cpu/mmu_64.h
index e3959e4407..d3c39dabb5 100644
--- a/arch/arm/cpu/mmu_64.h
+++ b/arch/arm/cpu/mmu_64.h
@@ -8,22 +8,19 @@
 #define UNCACHED_MEM    (PTE_BLOCK_MEMTYPE(MT_DEVICE_nGnRnE) | \
 			 PTE_BLOCK_OUTER_SHARE | \
 			 PTE_BLOCK_AF)
+#define MEM_ALLOC_WRITECOMBINE	(PTE_BLOCK_MEMTYPE(MT_NORMAL_NC) | \
+				 PTE_BLOCK_OUTER_SHARE | \
+				 PTE_BLOCK_AF)
 
-static inline unsigned long attrs_uncached_mem(void)
+static inline unsigned long attrs_xn(void)
 {
-	unsigned long attrs = UNCACHED_MEM;
-
 	switch (current_el()) {
 	case 3:
 	case 2:
-		attrs |= PTE_BLOCK_UXN;
-		break;
+		return PTE_BLOCK_UXN;
 	default:
-		attrs |= PTE_BLOCK_UXN | PTE_BLOCK_PXN;
-		break;
+		return PTE_BLOCK_UXN | PTE_BLOCK_PXN;
 	}
-
-	return attrs;
 }
 
 /*

-- 
2.39.5