[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/mach-ixp23xx/pci.c b/arch/arm/mach-ixp23xx/pci.c
index ba6b436..ac72f94 100644
--- a/arch/arm/mach-ixp23xx/pci.c
+++ b/arch/arm/mach-ixp23xx/pci.c
@@ -219,6 +219,12 @@
*IXP23XX_PCI_CPP_ADDR_BITS &= ~(1 << 1);
} else {
*IXP23XX_PCI_CPP_ADDR_BITS |= (1 << 1);
+
+ /*
+ * Enable coherency on A2 silicon.
+ */
+ if (arch_is_coherent())
+ *IXP23XX_CPP2XSI_CURR_XFER_REG3 &= ~IXP23XX_CPP2XSI_COH_OFF;
}
}