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author | Lennert Buytenhek <buytenh@wantstofly.org> | 2008-09-05 13:17:11 +0100 |
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committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2008-09-06 13:13:44 +0100 |
commit | 1ad77a876da48331451698cc4172c90ab9b6372f (patch) | |
tree | e5bbb4a782e5d6c98ff140fb2bf9a05759383a68 /arch | |
parent | 65846909d684d75906269df4f5f3474e1fef568b (diff) | |
download | linux-1ad77a876da48331451698cc4172c90ab9b6372f.tar.gz linux-1ad77a876da48331451698cc4172c90ab9b6372f.tar.bz2 linux-1ad77a876da48331451698cc4172c90ab9b6372f.zip |
[ARM] 5241/1: provide ioremap_wc()
This patch provides an ARM implementation of ioremap_wc().
We use different page table attributes depending on which CPU we
are running on:
- Non-XScale ARMv5 and earlier systems: The ARMv5 ARM documents four
possible mapping types (CB=00/01/10/11). We can't use any of the
cached memory types (CB=10/11), since that breaks coherency with
peripheral devices. Both CB=00 and CB=01 are suitable for _wc, and
CB=01 (Uncached/Buffered) allows the hardware more freedom than
CB=00, so we'll use that.
(The ARMv5 ARM seems to suggest that CB=01 is allowed to delay stores
but isn't allowed to merge them, but there is no other mapping type
we can use that allows the hardware to delay and merge stores, so
we'll go with CB=01.)
- XScale v1/v2 (ARMv5): same as the ARMv5 case above, with the slight
difference that on these platforms, CB=01 actually _does_ allow
merging stores. (If you want noncoalescing bufferable behavior
on Xscale v1/v2, you need to use XCB=101.)
- Xscale v3 (ARMv5) and ARMv6+: on these systems, we use TEXCB=00100
mappings (Inner/Outer Uncacheable in xsc3 parlance, Uncached Normal
in ARMv6 parlance).
The ARMv6 ARM explicitly says that any accesses to Normal memory can
be merged, which makes Normal memory more suitable for _wc mappings
than Device or Strongly Ordered memory, as the latter two mapping
types are guaranteed to maintain transaction number, size and order.
We use the Uncached variety of Normal mappings for the same reason
that we can't use C=1 mappings on ARMv5.
The xsc3 Architecture Specification documents TEXCB=00100 as being
Uncacheable and allowing coalescing of writes, which is also just
what we need.
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/arm/include/asm/io.h | 5 | ||||
-rw-r--r-- | arch/arm/include/asm/mach/map.h | 14 | ||||
-rw-r--r-- | arch/arm/mm/mmu.c | 20 |
3 files changed, 31 insertions, 8 deletions
diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h index 94a95d7fafd6..71934856fc22 100644 --- a/arch/arm/include/asm/io.h +++ b/arch/arm/include/asm/io.h @@ -61,8 +61,9 @@ extern void __raw_readsl(const void __iomem *addr, void *data, int longlen); #define MT_DEVICE_NONSHARED 1 #define MT_DEVICE_CACHED 2 #define MT_DEVICE_IXP2000 3 +#define MT_DEVICE_WC 4 /* - * types 4 onwards can be found in asm/mach/map.h and are undefined + * types 5 onwards can be found in asm/mach/map.h and are undefined * for ioremap */ @@ -215,11 +216,13 @@ extern void _memset_io(volatile void __iomem *, int, size_t); #define ioremap(cookie,size) __arm_ioremap(cookie, size, MT_DEVICE) #define ioremap_nocache(cookie,size) __arm_ioremap(cookie, size, MT_DEVICE) #define ioremap_cached(cookie,size) __arm_ioremap(cookie, size, MT_DEVICE_CACHED) +#define ioremap_wc(cookie,size) __arm_ioremap(cookie, size, MT_DEVICE_WC) #define iounmap(cookie) __iounmap(cookie) #else #define ioremap(cookie,size) __arch_ioremap((cookie), (size), MT_DEVICE) #define ioremap_nocache(cookie,size) __arch_ioremap((cookie), (size), MT_DEVICE) #define ioremap_cached(cookie,size) __arch_ioremap((cookie), (size), MT_DEVICE_CACHED) +#define ioremap_wc(cookie,size) __arch_ioremap((cookie), (size), MT_DEVICE_WC) #define iounmap(cookie) __arch_iounmap(cookie) #endif diff --git a/arch/arm/include/asm/mach/map.h b/arch/arm/include/asm/mach/map.h index 06f583b13999..9eb936e49cc3 100644 --- a/arch/arm/include/asm/mach/map.h +++ b/arch/arm/include/asm/mach/map.h @@ -18,13 +18,13 @@ struct map_desc { unsigned int type; }; -/* types 0-3 are defined in asm/io.h */ -#define MT_CACHECLEAN 4 -#define MT_MINICLEAN 5 -#define MT_LOW_VECTORS 6 -#define MT_HIGH_VECTORS 7 -#define MT_MEMORY 8 -#define MT_ROM 9 +/* types 0-4 are defined in asm/io.h */ +#define MT_CACHECLEAN 5 +#define MT_MINICLEAN 6 +#define MT_LOW_VECTORS 7 +#define MT_HIGH_VECTORS 8 +#define MT_MEMORY 9 +#define MT_ROM 10 #define MT_NONSHARED_DEVICE MT_DEVICE_NONSHARED #define MT_IXP2000_DEVICE MT_DEVICE_IXP2000 diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 25d9a11eb617..a713e40e1f1a 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -211,6 +211,12 @@ static struct mem_type mem_types[] = { PMD_SECT_TEX(1), .domain = DOMAIN_IO, }, + [MT_DEVICE_WC] = { /* ioremap_wc */ + .prot_pte = PROT_PTE_DEVICE, + .prot_l1 = PMD_TYPE_TABLE, + .prot_sect = PROT_SECT_DEVICE, + .domain = DOMAIN_IO, + }, [MT_CACHECLEAN] = { .prot_sect = PMD_TYPE_SECT | PMD_SECT_XN, .domain = DOMAIN_KERNEL, @@ -273,6 +279,20 @@ static void __init build_mem_type_table(void) } /* + * On non-Xscale3 ARMv5-and-older systems, use CB=01 + * (Uncached/Buffered) for ioremap_wc() mappings. On XScale3 + * and ARMv6+, use TEXCB=00100 mappings (Inner/Outer Uncacheable + * in xsc3 parlance, Uncached Normal in ARMv6 parlance). + */ + if (cpu_is_xsc3() || cpu_arch >= CPU_ARCH_ARMv6) { + mem_types[MT_DEVICE_WC].prot_pte_ext |= PTE_EXT_TEX(1); + mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_TEX(1); + } else { + mem_types[MT_DEVICE_WC].prot_pte |= L_PTE_BUFFERABLE; + mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_BUFFERABLE; + } + + /* * ARMv5 and lower, bit 4 must be set for page tables. * (was: cache "update-able on write" bit on ARM610) * However, Xscale cores require this bit to be cleared. |