arm: use a dummy struct device for ISA DMA use of the DMA API

This gets rid of the last NULL dev argument passed to the DMA API.
Signed-off-by: Christoph Hellwig <hch@lst.de>

arch/arm/kernel/dma-isa.c

@@ -55,6 +55,12 @@ static int isa_get_dma_residue(unsigned int chan, dma_t *dma)
 	return chan < 4 ? count : (count << 1);
 }
 
+static struct device isa_dma_dev = {
+	.init_name		= "fallback device",
+	.coherent_dma_mask	= ~(dma_addr_t)0,
+	.dma_mask		= &isa_dma_dev.coherent_dma_mask,
+};
+
 static void isa_enable_dma(unsigned int chan, dma_t *dma)
 {
 	if (dma->invalid) {
@@ -89,7 +95,7 @@ static void isa_enable_dma(unsigned int chan, dma_t *dma)
 			dma->sg = &dma->buf;
 			dma->sgcount = 1;
 			dma->buf.length = dma->count;
-			dma->buf.dma_address = dma_map_single(NULL,
+			dma->buf.dma_address = dma_map_single(&isa_dma_dev,
 				dma->addr, dma->count,
 				direction);
 		}

arch/arm/mach-rpc/dma.c

@@ -151,6 +151,12 @@ static void iomd_free_dma(unsigned int chan, dma_t *dma)
 	free_irq(idma->irq, idma);
 }
 
+static struct device isa_dma_dev = {
+	.init_name		= "fallback device",
+	.coherent_dma_mask	= ~(dma_addr_t)0,
+	.dma_mask		= &isa_dma_dev.coherent_dma_mask,
+};
+
 static void iomd_enable_dma(unsigned int chan, dma_t *dma)
 {
 	struct iomd_dma *idma = container_of(dma, struct iomd_dma, dma);
@@ -168,7 +174,7 @@ static void iomd_enable_dma(unsigned int chan, dma_t *dma)
 			idma->dma.sg = &idma->dma.buf;
 			idma->dma.sgcount = 1;
 			idma->dma.buf.length = idma->dma.count;
-			idma->dma.buf.dma_address = dma_map_single(NULL,
+			idma->dma.buf.dma_address = dma_map_single(&isa_dma_dev,
 				idma->dma.addr, idma->dma.count,
 				idma->dma.dma_mode == DMA_MODE_READ ?
 				DMA_FROM_DEVICE : DMA_TO_DEVICE);