[PATCH 01/17] ARM: MMU: add a Non-cacheable Normal executable memory type

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From: Paul Walmsley <paul@xxxxxxxxx>

Add a Non-cacheable Normal ARM executable memory type,
MT_MEMORY_NONCACHED.  This is needed for the OMAP3 SDRAM clock change
code, which must run from SRAM.  The SRAM must be marked as
non-cacheable memory to avoid dirty cache line writebacks to SDRAM
while the SDRAM controller is paused.

Signed-off-by: Paul Walmsley <paul@xxxxxxxxx>
---
 arch/arm/include/asm/mach/map.h |    1 +
 arch/arm/mm/mmu.c               |   23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/arch/arm/include/asm/mach/map.h b/arch/arm/include/asm/mach/map.h
index 39d949b..58cf91f 100644
--- a/arch/arm/include/asm/mach/map.h
+++ b/arch/arm/include/asm/mach/map.h
@@ -26,6 +26,7 @@ struct map_desc {
 #define MT_HIGH_VECTORS		8
 #define MT_MEMORY		9
 #define MT_ROM			10
+#define MT_MEMORY_NONCACHED	11
 
 #ifdef CONFIG_MMU
 extern void iotable_init(struct map_desc *, int);
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 7f36c82..9ad6413 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -242,6 +242,10 @@ static struct mem_type mem_types[] = {
 		.prot_sect = PMD_TYPE_SECT,
 		.domain    = DOMAIN_KERNEL,
 	},
+	[MT_MEMORY_NONCACHED] = {
+		.prot_sect = PMD_TYPE_SECT | PMD_SECT_AP_WRITE,
+		.domain    = DOMAIN_KERNEL,
+	},
 };
 
 const struct mem_type *get_mem_type(unsigned int type)
@@ -405,9 +409,28 @@ static void __init build_mem_type_table(void)
 		kern_pgprot |= L_PTE_SHARED;
 		vecs_pgprot |= L_PTE_SHARED;
 		mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
+		mem_types[MT_MEMORY_NONCACHED].prot_sect |= PMD_SECT_S;
 #endif
 	}
 
+	/*
+	 * Non-cacheable Normal - intended for memory areas that must
+	 * not cause cache line evictions when used
+	 */
+	if (cpu_arch >= CPU_ARCH_ARMv6) {
+		if (cpu_arch >= CPU_ARCH_ARMv7 && (cr & CR_TRE)) {
+			/* Non-cacheable Normal is XCB = 001 */
+			mem_types[MT_MEMORY_NONCACHED].prot_sect |=
+				PMD_SECT_BUFFERED;
+		} else {
+			/* For both ARMv6 and non-TEX-remapping ARMv7 */
+			mem_types[MT_MEMORY_NONCACHED].prot_sect |=
+				PMD_SECT_TEX(1);
+		}
+	} else {
+		mem_types[MT_MEMORY_NONCACHED].prot_sect |= PMD_SECT_BUFFERABLE;
+	}
+
 	for (i = 0; i < 16; i++) {
 		unsigned long v = pgprot_val(protection_map[i]);
 		protection_map[i] = __pgprot(v | user_pgprot);
-- 
1.5.4.3

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