tile PCI RC: add dma_get_required_mask()

The standard kernel function dma_get_required_mask() uses the
highest DRAM address to determine if 32-bit or 64-bit DMA addressing
is needed.  This only works on architectures that have direct mapping
between the PA and the PCI address space, i.e. those that don't have
I/O TLBs or have I/O TLB but choose to use direct mapping.  Neither
of these are true for tilegx.  Whether to use 64-bit DMA should depend
on the PCI device's capability only, not on the amount of DRAM
installeds, so we now advertise a 64-bit DMA mask unconditionally.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/tile/include/asm/dma-mapping.h b/arch/tile/include/asm/dma-mapping.h
index 4a60059..6f522d5 100644
--- a/arch/tile/include/asm/dma-mapping.h
+++ b/arch/tile/include/asm/dma-mapping.h
@@ -20,6 +20,10 @@
 #include <linux/cache.h>
 #include <linux/io.h>
 
+#ifdef __tilegx__
+#define ARCH_HAS_DMA_GET_REQUIRED_MASK
+#endif
+
 extern struct dma_map_ops *tile_dma_map_ops;
 extern struct dma_map_ops *gx_pci_dma_map_ops;
 extern struct dma_map_ops *gx_legacy_pci_dma_map_ops;