drivers: uio_dmem_genirq: Don't use DMA_ERROR_CODE to indicate unmapped regions

DMA_ERROR_CODE is not defined on all architectures and is architecture
specific.  Instead, use the constant, ~0 to indicate unmapped regions.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Damian Hobson-Garcia <dhobsong@igel.co.jp>
Cc: "Hans J. Koch" <hjk@hansjkoch.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/DocBook/uio-howto.tmpl

@@ -771,7 +771,7 @@ framework to set up sysfs files for this region. Simply leave it alone.
 	<varname>/sys/class/uio/uioX/maps/mapY/*</varname>.
 	The dynmaic memory regions will be freed when the UIO device file is
 	closed. When no processes are holding the device file open, the address
-	returned to userspace is DMA_ERROR_CODE.
+	returned to userspace is ~0.
 	</para>
 </sect1>
 

drivers/uio/uio_dmem_genirq.c

@@ -29,6 +29,7 @@
 #include <linux/of_address.h>
 
 #define DRIVER_NAME "uio_dmem_genirq"
+#define DMEM_MAP_ERROR (~0)
 
 struct uio_dmem_genirq_platdata {
 	struct uio_info *uioinfo;
@@ -60,6 +61,7 @@ static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
 		addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
 				(dma_addr_t *)&uiomem->addr, GFP_KERNEL);
 		if (!addr) {
+			uiomem->addr = DMEM_MAP_ERROR;
 			ret = -ENOMEM;
 			break;
 		}
@@ -95,7 +97,7 @@ static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
 		dma_free_coherent(&priv->pdev->dev, uiomem->size,
 				priv->dmem_region_vaddr[dmem_region++],
 				uiomem->addr);
-		uiomem->addr = DMA_ERROR_CODE;
+		uiomem->addr = DMEM_MAP_ERROR;
 		++uiomem;
 	}
 
@@ -238,7 +240,7 @@ static int uio_dmem_genirq_probe(struct platform_device *pdev)
 			break;
 		}
 		uiomem->memtype = UIO_MEM_PHYS;
-		uiomem->addr = DMA_ERROR_CODE;
+		uiomem->addr = DMEM_MAP_ERROR;
 		uiomem->size = pdata->dynamic_region_sizes[i];
 		++uiomem;
 	}