ARM/dma-mapping: merge __dma_supported into arm_dma_supported

Merge __dma_supported into its only caller, and move the resulting
function so that it doesn't need a forward declaration. Also mark
it static as there are no callers outside of dma-mapping.c.

Signed-off-by: Christoph Hellwig <[e-mail]>

arch/arm/include/asm/dma-iommu.h

···
 					struct dma_iommu_mapping *mapping);
 void arm_iommu_detach_device(struct device *dev);
 
-int arm_dma_supported(struct device *dev, u64 mask);
-
 #endif /* __KERNEL__ */
 #endif

arch/arm/mm/dma-mapping.c

···
 	__dma_page_cpu_to_dev(page, offset, size, dir);
 }
 
+/*
+ * Return whether the given device DMA address mask can be supported
+ * properly.  For example, if your device can only drive the low 24-bits
+ * during bus mastering, then you would pass 0x00ffffff as the mask
+ * to this function.
+ */
+static int arm_dma_supported(struct device *dev, u64 mask)
+{
+	unsigned long max_dma_pfn = min(max_pfn - 1, arm_dma_pfn_limit);
+
+	/*
+	 * Translate the device's DMA mask to a PFN limit.  This
+	 * PFN number includes the page which we can DMA to.
+	 */
+	return dma_to_pfn(dev, mask) >= max_dma_pfn;
+}
+
 const struct dma_map_ops arm_dma_ops = {
 	.alloc			= arm_dma_alloc,
 	.free			= arm_dma_free,
···
 	.get_required_mask	= dma_direct_get_required_mask,
 };
 EXPORT_SYMBOL(arm_coherent_dma_ops);
-
-static int __dma_supported(struct device *dev, u64 mask)
-{
-	unsigned long max_dma_pfn = min(max_pfn - 1, arm_dma_pfn_limit);
-
-	/*
-	 * Translate the device's DMA mask to a PFN limit.  This
-	 * PFN number includes the page which we can DMA to.
-	 */
-	if (dma_to_pfn(dev, mask) < max_dma_pfn)
-		return 0;
-	return 1;
-}
 
 static void __dma_clear_buffer(struct page *page, size_t size, int coherent_flag)
 {
···
 	for_each_sg(sg, s, nents, i)
 		ops->sync_single_for_device(dev, sg_dma_address(s), s->length,
 					    dir);
-}
-
-/*
- * Return whether the given device DMA address mask can be supported
- * properly.  For example, if your device can only drive the low 24-bits
- * during bus mastering, then you would pass 0x00ffffff as the mask
- * to this function.
- */
-int arm_dma_supported(struct device *dev, u64 mask)
-{
-	return __dma_supported(dev, mask);
 }
 
 static const struct dma_map_ops *arm_get_dma_map_ops(bool coherent)