[PATCH v2 4/5] dt: add of_platform_populate() for creating device from the device tree

[Grant Likely <grant.likely@secretlab.ca>]

of_platform_populate() is similar to of_platform_bus_probe() except
that it strictly enforces that all device nodes must have a compatible
property, and it can be used to register devices (not buses) which are
children of the root node.

This patch also modifies MPC5200 support to use the new function.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
 arch/powerpc/platforms/52xx/mpc52xx_common.c |   10 ++---
 drivers/of/platform.c                        |   54 ++++++++++++++++++++++++--
 include/linux/of_platform.h                  |    3 +
 3 files changed, 57 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/platforms/52xx/mpc52xx_common.c b/arch/powerpc/platforms/52xx/mpc52xx_common.c
index 41f3a7e..5767a8a 100644
--- a/arch/powerpc/platforms/52xx/mpc52xx_common.c
+++ b/arch/powerpc/platforms/52xx/mpc52xx_common.c
@@ -97,13 +97,11 @@ struct mpc52xx_gpio_wkup __iomem *wkup_gpio;
  *					of the localplus bus to the of_platform
  *					bus.
  */
-void __init
-mpc52xx_declare_of_platform_devices(void)
+void __init mpc52xx_declare_of_platform_devices(void)
 {
-	/* Find every child of the SOC node and add it to of_platform */
-	if (of_platform_bus_probe(NULL, mpc52xx_bus_ids, NULL))
-		printk(KERN_ERR __FILE__ ": "
-			"Error while probing of_platform bus\n");
+	/* Find all the 'platform' devices and register them. */
+	if (of_platform_populate(NULL, mpc52xx_bus_ids, NULL))
+		pr_err(__FILE__ ": Error while populating devices from DT\n");
 }
 
 /*
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 63d3cb7..9b785be 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -221,19 +221,26 @@ EXPORT_SYMBOL(of_platform_device_create);
  */
 static int of_platform_bus_create(struct device_node *bus,
 				  const struct of_device_id *matches,
-				  struct device *parent)
+				  struct device *parent, bool strict)
 {
 	struct device_node *child;
 	struct platform_device *dev;
 	int rc = 0;
 
+	/* Make sure it has a compatible property */
+	if (strict && (!of_get_property(bus, "compatible", NULL))) {
+		pr_debug("%s() - skipping %s, no compatible prop\n",
+			 __func__, bus->full_name);
+		return 0;
+	}
+
 	dev = of_platform_device_create(bus, NULL, parent);
 	if (!dev || !of_match_node(matches, bus))
 		return 0;
 
 	for_each_child_of_node(bus, child) {
 		pr_debug("   create child: %s\n", child->full_name);
-		rc = of_platform_bus_create(child, matches, &dev->dev);
+		rc = of_platform_bus_create(child, matches, &dev->dev, strict);
 		if (rc) {
 			of_node_put(child);
 			break;
@@ -267,11 +274,11 @@ int of_platform_bus_probe(struct device_node *root,
 
 	/* Do a self check of bus type, if there's a match, create children */
 	if (of_match_node(matches, root)) {
-		rc = of_platform_bus_create(root, matches, parent);
+		rc = of_platform_bus_create(root, matches, parent, false);
 	} else for_each_child_of_node(root, child) {
 		if (!of_match_node(matches, child))
 			continue;
-		rc = of_platform_bus_create(child, matches, parent);
+		rc = of_platform_bus_create(child, matches, parent, false);
 		if (rc)
 			break;
 	}
@@ -280,4 +287,43 @@ int of_platform_bus_probe(struct device_node *root,
 	return rc;
 }
 EXPORT_SYMBOL(of_platform_bus_probe);
+
+/**
+ * of_platform_populate() - Populate platform_devices from device tree data
+ * @root: parent of the first level to probe or NULL for the root of the tree
+ * @matches: match table, NULL to use the default
+ * @parent: parent to hook devices from, NULL for toplevel
+ *
+ * Similar to of_platform_bus_probe(), this function walks the device tree
+ * and creates devices from nodes.  It differs in that it follows the modern
+ * convention of requiring all device nodes to have a 'compatible' property,
+ * and it is suitable for creating devices which are children of the root
+ * node (of_platform_bus_probe will only create children of the root which
+ * are selected by the @matches argument).
+ *
+ * New board support should be using this function instead of
+ * of_platform_bus_probe().
+ *
+ * Returns 0 on success, < 0 on failure.
+ */
+int of_platform_populate(struct device_node *root,
+			const struct of_device_id *matches,
+			struct device *parent)
+{
+	struct device_node *child;
+	int rc = 0;
+
+	root = root ? of_node_get(root) : of_find_node_by_path("/");
+	if (!root)
+		return -EINVAL;
+
+	for_each_child_of_node(root, child) {
+		rc = of_platform_bus_create(child, matches, parent, true);
+		if (rc)
+			break;
+	}
+
+	of_node_put(root);
+	return rc;
+}
 #endif /* !CONFIG_SPARC */
diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h
index fb51ae3..43c723d 100644
--- a/include/linux/of_platform.h
+++ b/include/linux/of_platform.h
@@ -55,6 +55,9 @@ extern struct platform_device *of_platform_device_create(struct device_node *np,
 extern int of_platform_bus_probe(struct device_node *root,
 				 const struct of_device_id *matches,
 				 struct device *parent);
+extern int of_platform_populate(struct device_node *root,
+				const struct of_device_id *matches,
+				struct device *parent);
 #endif /* !CONFIG_SPARC */
 
 #endif /* CONFIG_OF_DEVICE */