dma-mapping: dma-mapping.h: add dma_set_coherent_mask

dma_set_coherent_mask corresponds to pci_set_consistent_dma_mask.  This is
necessary to move to the generic device model DMA API from the PCI bus
specific API in the long term.

dma_set_coherent_mask works in the exact same way that
pci_set_consistent_dma_mask does.  So this patch also changes
pci_set_consistent_dma_mask to call dma_set_coherent_mask.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: James Bottomley <James.Bottomley@suse.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/DMA-API.txt

@@ -167,6 +167,16 @@ parameters if it is.
 
 Returns: 0 if successful and a negative error if not.
 
+int
+dma_set_coherent_mask(struct device *dev, u64 mask)
+int
+pci_set_consistent_dma_mask(struct pci_device *dev, u64 mask)
+
+Checks to see if the mask is possible and updates the device
+parameters if it is.
+
+Returns: 0 if successful and a negative error if not.
+
 u64
 dma_get_required_mask(struct device *dev)
 

drivers/pci/pci.c

@@ -2315,12 +2315,11 @@ pci_set_dma_mask(struct pci_dev *dev, u64 mask)
 int
 pci_set_consistent_dma_mask(struct pci_dev *dev, u64 mask)
 {
-	if (!pci_dma_supported(dev, mask))
-		return -EIO;
+	int ret = dma_set_coherent_mask(&dev->dev, mask);
+	if (ret)
+		return ret;
 
-	dev->dev.coherent_dma_mask = mask;
 	dev_dbg(&dev->dev, "using %dbit consistent DMA mask\n", fls64(mask));
-
 	return 0;
 }
 #endif

include/linux/dma-mapping.h

@@ -127,6 +127,14 @@ static inline u64 dma_get_mask(struct device *dev)
 	return DMA_BIT_MASK(32);
 }
 
+static inline int dma_set_coherent_mask(struct device *dev, u64 mask)
+{
+	if (!dma_supported(dev, mask))
+		return -EIO;
+	dev->coherent_dma_mask = mask;
+	return 0;
+}
+
 extern u64 dma_get_required_mask(struct device *dev);
 
 static inline unsigned int dma_get_max_seg_size(struct device *dev)