set_arch_dma_coherent_ops is called from of_dma_configure in order to
swizzle the architectural dma-mapping functions over to a cache-coherent
implementation. This is currently implemented only for ARM.

In anticipation of re-using this mechanism for IOMMU-backed dma-mapping
ops too, this patch replaces the function with a broader
arch_setup_dma_ops callback which will be extended in future.

Signed-off-by: Will Deacon <will.dea...@arm.com>
---
 arch/arm/include/asm/dma-mapping.h |  8 ++++----
 drivers/of/platform.c              | 31 +++++++++++++------------------
 include/linux/dma-mapping.h        |  7 ++-----
 3 files changed, 19 insertions(+), 27 deletions(-)

diff --git a/arch/arm/include/asm/dma-mapping.h 
b/arch/arm/include/asm/dma-mapping.h
index 85738b200023..dc3420e77758 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -121,12 +121,12 @@ static inline unsigned long dma_max_pfn(struct device 
*dev)
 }
 #define dma_max_pfn(dev) dma_max_pfn(dev)
 
-static inline int set_arch_dma_coherent_ops(struct device *dev)
+static inline void arch_setup_dma_ops(struct device *dev, bool coherent)
 {
-       set_dma_ops(dev, &arm_coherent_dma_ops);
-       return 0;
+       if (coherent)
+               set_dma_ops(dev, &arm_coherent_dma_ops);
 }
-#define set_arch_dma_coherent_ops(dev) set_arch_dma_coherent_ops(dev)
+#define arch_setup_dma_ops arch_setup_dma_ops
 
 static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
 {
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 3b64d0bf5bba..ff1f4e9afccb 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -164,6 +164,8 @@ static void of_dma_configure(struct device *dev)
 {
        u64 dma_addr, paddr, size;
        int ret;
+       bool coherent;
+       unsigned long offset;
 
        /*
         * Set default dma-mask to 32 bit. Drivers are expected to setup
@@ -178,28 +180,21 @@ static void of_dma_configure(struct device *dev)
        if (!dev->dma_mask)
                dev->dma_mask = &dev->coherent_dma_mask;
 
-       /*
-        * if dma-coherent property exist, call arch hook to setup
-        * dma coherent operations.
-        */
-       if (of_dma_is_coherent(dev->of_node)) {
-               set_arch_dma_coherent_ops(dev);
-               dev_dbg(dev, "device is dma coherent\n");
-       }
-
-       /*
-        * if dma-ranges property doesn't exist - just return else
-        * setup the dma offset
-        */
        ret = of_dma_get_range(dev->of_node, &dma_addr, &paddr, &size);
        if (ret < 0) {
-               dev_dbg(dev, "no dma range information to setup\n");
-               return;
+               dma_addr = offset = 0;
+               size = dev->coherent_dma_mask;
+       } else {
+               offset = PFN_DOWN(paddr - dma_addr);
+               dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", dev->dma_pfn_offset);
        }
+       dev->dma_pfn_offset = offset;
+
+       coherent = of_dma_is_coherent(dev->of_node);
+       dev_dbg(dev, "device is%sdma coherent\n",
+               coherent ? " " : " not ");
 
-       /* DMA ranges found. Calculate and set dma_pfn_offset */
-       dev->dma_pfn_offset = PFN_DOWN(paddr - dma_addr);
-       dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", dev->dma_pfn_offset);
+       arch_setup_dma_ops(dev, coherent);
 }
 
 /**
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index d5d388160f42..8a1560f95d4a 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -129,11 +129,8 @@ static inline int dma_coerce_mask_and_coherent(struct 
device *dev, u64 mask)
 
 extern u64 dma_get_required_mask(struct device *dev);
 
-#ifndef set_arch_dma_coherent_ops
-static inline int set_arch_dma_coherent_ops(struct device *dev)
-{
-       return 0;
-}
+#ifndef arch_setup_dma_ops
+static inline void arch_setup_dma_ops(struct device *dev, bool coherent) { }
 #endif
 
 static inline unsigned int dma_get_max_seg_size(struct device *dev)
-- 
2.1.1

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