[ARM] 3439/2: xsc3: add I/O coherency support
Patch from Lennert Buytenhek
This patch adds support for the I/O coherent cache available on the
xsc3. The approach is to provide a simple API to determine whether the
chipset supports coherency by calling arch_is_coherent() and then
setting the appropriate system memory PTE and PMD bits. In addition,
we call this API on dma_alloc_coherent() and dma_map_single() calls.
A generic version exists that will compile out all the coherency-related
code that is not needed on the majority of ARM systems.
Note that we do not check for coherency in the dma_alloc_writecombine()
function as that still requires a special PTE setting. We also don't
touch dma_mmap_coherent() as that is a special ARM-only API that is by
definition only used on non-coherent system.
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mm/consistent.c b/arch/arm/mm/consistent.c
index 8a1bfcd..50e6b6b 100644
--- a/arch/arm/mm/consistent.c
+++ b/arch/arm/mm/consistent.c
@@ -18,6 +18,7 @@
#include <linux/device.h>
#include <linux/dma-mapping.h>
+#include <asm/memory.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/sizes.h>
@@ -272,6 +273,17 @@
void *
dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
{
+ if (arch_is_coherent()) {
+ void *virt;
+
+ virt = kmalloc(size, gfp);
+ if (!virt)
+ return NULL;
+ *handle = virt_to_dma(dev, virt);
+
+ return virt;
+ }
+
return __dma_alloc(dev, size, handle, gfp,
pgprot_noncached(pgprot_kernel));
}
@@ -350,6 +362,11 @@
WARN_ON(irqs_disabled());
+ if (arch_is_coherent()) {
+ kfree(cpu_addr);
+ return;
+ }
+
size = PAGE_ALIGN(size);
spin_lock_irqsave(&consistent_lock, flags);
diff --git a/arch/arm/mm/mm-armv.c b/arch/arm/mm/mm-armv.c
index 5e5d05b..f14b2d0 100644
--- a/arch/arm/mm/mm-armv.c
+++ b/arch/arm/mm/mm-armv.c
@@ -389,6 +389,17 @@
kern_pgprot = user_pgprot = cp->pte;
/*
+ * Enable CPU-specific coherency if supported.
+ * (Only available on XSC3 at the moment.)
+ */
+ if (arch_is_coherent()) {
+ if (cpu_is_xsc3()) {
+ mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
+ mem_types[MT_MEMORY].prot_pte |= L_PTE_COHERENT;
+ }
+ }
+
+ /*
* ARMv6 and above have extended page tables.
*/
if (cpu_arch >= CPU_ARCH_ARMv6 && (cr & CR_XP)) {
diff --git a/arch/arm/mm/proc-xsc3.S b/arch/arm/mm/proc-xsc3.S
index b9dfce5..80873b3 100644
--- a/arch/arm/mm/proc-xsc3.S
+++ b/arch/arm/mm/proc-xsc3.S
@@ -371,7 +371,7 @@
ENTRY(cpu_xsc3_set_pte)
str r1, [r0], #-2048 @ linux version
- bic r2, r1, #0xff0
+ bic r2, r1, #0xdf0 @ Keep C, B, coherency bits
orr r2, r2, #PTE_TYPE_EXT @ extended page
eor r3, r1, #L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_WRITE | L_PTE_DIRTY