sparc/iommu: return error codes from .map_sg() ops

The .map_sg() op now expects an error code instead of zero on failure.

Returning an errno from __sbus_iommu_map_sg() results in
sbus_iommu_map_sg_gflush() and sbus_iommu_map_sg_pflush() returning an
errno, as those functions are wrappers around __sbus_iommu_map_sg().
Signed-off-by: Martin Oliveira <martin.oliveira@eideticom.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Christoph Hellwig <hch@lst.de>

arch/sparc/kernel/iommu.c

@@ -448,7 +448,7 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
 	iommu = dev->archdata.iommu;
 	strbuf = dev->archdata.stc;
 	if (nelems == 0 || !iommu)
-		return 0;
+		return -EINVAL;
 
 	spin_lock_irqsave(&iommu->lock, flags);
 
@@ -580,7 +580,7 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
 	}
 	spin_unlock_irqrestore(&iommu->lock, flags);
 
-	return 0;
+	return -EINVAL;
 }
 
 /* If contexts are being used, they are the same in all of the mappings

arch/sparc/kernel/pci_sun4v.c

@@ -486,7 +486,7 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist,
 
 	iommu = dev->archdata.iommu;
 	if (nelems == 0 || !iommu)
-		return 0;
+		return -EINVAL;
 	atu = iommu->atu;
 
 	prot = HV_PCI_MAP_ATTR_READ;
@@ -619,7 +619,7 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist,
 	}
 	local_irq_restore(flags);
 
-	return 0;
+	return -EINVAL;
 }
 
 static void dma_4v_unmap_sg(struct device *dev, struct scatterlist *sglist,

arch/sparc/mm/iommu.c

@@ -256,7 +256,7 @@ static int __sbus_iommu_map_sg(struct device *dev, struct scatterlist *sgl,
 		sg->dma_address =__sbus_iommu_map_page(dev, sg_page(sg),
 				sg->offset, sg->length, per_page_flush);
 		if (sg->dma_address == DMA_MAPPING_ERROR)
-			return 0;
+			return -EIO;
 		sg->dma_length = sg->length;
 	}