[PATCH 3/3 v2] of/device: Register children with a compatible value in of_platform_bus_probe()

[Lan Chunhe]

Currently, of_platform_bus_probe() completely skips nodes which do not
explicitly match the 'matches' table passed in.  Or, if the root node
matches, then it registers all the children unconditionally.  However,
there are situations, such as registering devices from the root node,
when it is desirable to register child nodes, but only if they actually
represent devices.  For example, the root node may contain both a local
bus and a PCI device, but it also contains the chosen, aliases and cpus
nodes which don't represent real devices.

This patch changes of_platform_bus_probe() to register all nodes at the
top level if they either match the matches table (the current behaviour),
or if they have a 'compatible' value (indicating it represents a device).

Signed-off-by: Lan Chunhe <b25806 at freescale.com>
---
 drivers/of/platform.c |   28 +++++++++++++++++++++++-----
 1 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 5b4a07f..02755ab 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -714,6 +714,8 @@ int of_platform_bus_probe(struct device_node *root,
 	struct device_node *child;
 	struct platform_device *dev;
 	int rc = 0;
+	const void *compat;
+	const struct of_device_id *match;
 
 	if (WARN_ON(!matches || matches == OF_NO_DEEP_PROBE))
 		return -EINVAL;
@@ -741,16 +743,32 @@ int of_platform_bus_probe(struct device_node *root,
 		rc = of_platform_bus_create(root, matches, &dev->dev);
 		goto bail;
 	}
+
+	/*
+	 * Register each child node if either:
+	 *  a) it has a 'compatible' value indicating they are a device, or
+	 *  b) it is specified by the 'matches' table (by name or device_type)
+	 * If a node is specified in the matches table, then all its children
+	 * also get registered.
+	 */
 	for_each_child_of_node(root, child) {
-		if (!of_match_node(matches, child))
+		compat = of_get_property(child, "compatible", NULL);
+		match = of_match_node(matches, child);
+		if (!compat && !match)
 			continue;
 
-		pr_debug("  match: %s\n", child->full_name);
+		pr_debug("  register device: %s\n", child->full_name);
 		dev = of_platform_device_create(child, NULL, parent);
-		if (dev == NULL)
+		if (!dev) {
 			rc = -ENOMEM;
-		else
-			rc = of_platform_bus_create(child, matches, &dev->dev);
+			of_node_put(child);
+			break;
+		}
+		if (!match)
+			continue;
+
+		pr_debug("  register children of: %s\n", child->full_name);
+		rc = of_platform_bus_create(child, matches, &dev->dev);
 		if (rc) {
 			of_node_put(child);
 			break;
-- 
1.5.4.5