Arnd,

On 05/26/2011 08:11 AM, Arnd Bergmann wrote:

On Wednesday 25 May 2011, Rob Herring wrote:

quoted

From: Rob Herring<redacted>

Add support to the platform bus scanning to call custom device creation
functions. This enables creation of non-platform devices like amba_bus.

Cc: Jeremy Kerr<redacted>
Cc: Grant Likely<redacted>
Cc: linux at arm.linux.org.uk
Cc: arnd at arndb.de
Cc: Linus Walleij<redacted>
Signed-off-by: Rob Herring<redacted>

This creates a confusing mix of match table entries: Normally,
all entries in the match table are meant to identify child buses,
but if I read your patch correctly, you now also need to match
on the amba devices themselves, including the creation of
platform devices for each child device node under an amba
device.

We should only create devices for each matching bus and the immediate 
children of each bus. A child device of an amba device would be 
something like an i2c bus which we don't want to create devices for. Or 
am I missing something?

I don't think that was the intention. Maybe we need to pass
two match tables into of_platform_bus_probe() instead:
one to identify the buses, and another one that is used
to create the actual devices.

That was my original thinking too, but some reason I had concluded 1 
could get by with just 1 table. After more thought, I think you are 
right. In fact, I broke platform device creation with this patch. I need 
to be able to tell if no match means create a platform device (child of 
bus) or not (child of a device).

Here's an updated version with just the interesting hunk. I've tested it 
with a made up bus structure that looks something like this:

soc bus
  -plat dev
  -amba dev
  -sub-bus
    -plat dev
    -amba dev
  -plat dev

As of_platform_bus_probe is not recommended to be used by Grant, I only 
plan to add 2 match tables to of_platform_bus_populate.

@@ -234,18 +237,32 @@ static int of_platform_bus_create(struct 

device_node *bus,
  		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, strict);
-		if (rc) {
-			of_node_put(child);
-			break;
+	id = of_match_node(bus_matches, bus);
+	if (id) {
+		dev = of_platform_device_create(bus, NULL, parent);
+		if (!dev)
+			return 0;
+		for_each_child_of_node(bus, child) {
+			pr_debug("   create child: %s\n", child->full_name);
+			rc = of_platform_bus_create(child, bus_matches,
+						    dev_matches, dev, strict);
+			if (rc) {
+				of_node_put(child);
+				break;
+			}
  		}
+		return rc;
  	}
+
+	id = of_match_node(dev_matches, bus);
+	mdata = id ? id->data : NULL;
+	if (id && mdata && mdata->dev_create)
+		dev = mdata->dev_create(bus, parent);
+	else
+		dev = of_platform_device_create(bus, NULL, parent);
+	if (!dev)
+		return 0;
+
  	return rc;
  }


Rob