dma-mapping: replace set_arch_dma_coherent_ops with arch_setup_dma_ops

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.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

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)