iommu: tegra/gart: Add device tree support

This commit adds device tree support for the GART hardware available on
NVIDIA Tegra 20 SoCs.
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

Documentation/devicetree/bindings/iommu/nvidia,tegra20-gart.txt

+NVIDIA Tegra 20 GART
+
+Required properties:
+- compatible: "nvidia,tegra20-gart"
+- reg: Two pairs of cells specifying the physical address and size of
+  the memory controller registers and the GART aperture respectively.
+
+Example:
+
+	gart: gart@7000f000 {
+		compatible = "nvidia,tegra20-gart";
+		reg = < 0x7000f000 0x00000100    /* controller registers */
+		        0x58000000 0x02000000 >; /* GART aperture */
+	};

drivers/iommu/tegra-gart.c

@@ -29,6 +29,7 @@
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/iommu.h>
+#include <linux/of.h>
 
 #include <asm/cacheflush.h>
 
@@ -422,6 +423,14 @@ const struct dev_pm_ops tegra_gart_pm_ops = {
 	.resume		= tegra_gart_resume,
 };
 
+#ifdef CONFIG_OF
+static struct of_device_id tegra_gart_of_match[] __devinitdata = {
+	{ .compatible = "nvidia,tegra20-gart", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, tegra_gart_of_match);
+#endif
+
 static struct platform_driver tegra_gart_driver = {
 	.probe		= tegra_gart_probe,
 	.remove		= tegra_gart_remove,
@@ -429,6 +438,7 @@ static struct platform_driver tegra_gart_driver = {
 		.owner	= THIS_MODULE,
 		.name	= "tegra-gart",
 		.pm	= &tegra_gart_pm_ops,
+		.of_match_table = of_match_ptr(tegra_gart_of_match),
 	},
 };
 
@@ -448,4 +458,5 @@ module_exit(tegra_gart_exit);
 
 MODULE_DESCRIPTION("IOMMU API for GART in Tegra20");
 MODULE_AUTHOR("Hiroshi DOYU <hdoyu@nvidia.com>");
+MODULE_ALIAS("platform:tegra-gart");
 MODULE_LICENSE("GPL v2");