powerpc/pci: add dma_set_mask to pci_controller_ops

Some systems only need to deal with DMA masks for PCI devices.
For these systems, we can avoid the need for a platform hook and
instead use a pci controller based hook.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/pci-bridge.h

@@ -36,6 +36,8 @@ struct pci_controller_ops {
 					  int nvec, int type);
 	void		(*teardown_msi_irqs)(struct pci_dev *dev);
 #endif
+
+	int             (*dma_set_mask)(struct pci_dev *dev, u64 dma_mask);
 };
 
 /*

arch/powerpc/kernel/dma.c

@@ -248,6 +248,14 @@ int dma_set_mask(struct device *dev, u64 dma_mask)
 {
 	if (ppc_md.dma_set_mask)
 		return ppc_md.dma_set_mask(dev, dma_mask);
+
+	if (dev_is_pci(dev)) {
+		struct pci_dev *pdev = to_pci_dev(dev);
+		struct pci_controller *phb = pci_bus_to_host(pdev->bus);
+		if (phb->controller_ops.dma_set_mask)
+			return phb->controller_ops.dma_set_mask(pdev, dma_mask);
+	}
+
 	return __dma_set_mask(dev, dma_mask);
 }
 EXPORT_SYMBOL(dma_set_mask);