of/platform: add error reporting to of_amba_device_create()

Add error reporting to of_amba_device_create() so the user knows
when (and why) some device tree nodes fail to initialize.

[ The issue was spotted on Universal C210 board (using revision 0 of
  ARM Exynos4210 SoC) on which initialization was silently failing
  for PL330 MDMA1 device tree node (it was using the wrong addres
  resulting in amba_device_add() returning -ENODEV). ]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

drivers/of/platform.c

@@ -264,8 +264,11 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
 		return NULL;
 
 	dev = amba_device_alloc(NULL, 0, 0);
-	if (!dev)
+	if (!dev) {
+		pr_err("%s(): amba_device_alloc() failed for %s\n",
+		       __func__, node->full_name);
 		return NULL;
+	}
 
 	/* setup generic device info */
 	dev->dev.coherent_dma_mask = ~0;
@@ -290,12 +293,18 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
 		dev->irq[i] = irq_of_parse_and_map(node, i);
 
 	ret = of_address_to_resource(node, 0, &dev->res);
-	if (ret)
+	if (ret) {
+		pr_err("%s(): of_address_to_resource() failed (%d) for %s\n",
+		       __func__, ret, node->full_name);
 		goto err_free;
+	}
 
 	ret = amba_device_add(dev, &iomem_resource);
-	if (ret)
+	if (ret) {
+		pr_err("%s(): amba_device_add() failed (%d) for %s\n",
+		       __func__, ret, node->full_name);
 		goto err_free;
+	}
 
 	return dev;
 
@@ -374,6 +383,10 @@ static int of_platform_bus_create(struct device_node *bus,
 	}
 
 	if (of_device_is_compatible(bus, "arm,primecell")) {
+		/*
+		 * Don't return an error here to keep compatibility with older
+		 * device tree files.
+		 */
 		of_amba_device_create(bus, bus_id, platform_data, parent);
 		return 0;
 	}