[PATCH] add modalias file for of_devices to sysfs

[Olaf Hering]

modalias files are supposed to be there for every node.
They allow module autoloading, and it is possible to match required kernel modules.
Tested on Efika:

	==> /sys/devices/f0000000.builtin/f0003a00.ata/devspec <==
	/builtin at F0000000/ata at F0003A00

	==> /sys/devices/f0000000.builtin/f0003a00.ata/modalias <==
	of:NataTataCmpc5200b-ataCmpc5200-ata

Also add a newline to the 'devspec' file output.

Signed-off-by: Olaf Hering <olaf at aepfle.de>

---
 arch/powerpc/kernel/of_device.c   |   47 ++++++++++++++++++++++++++++----------
 arch/powerpc/kernel/of_platform.c |    3 ++
 2 files changed, 38 insertions(+), 12 deletions(-)

Index: b/arch/powerpc/kernel/of_device.c
===================================================================
--- a/arch/powerpc/kernel/of_device.c
+++ b/arch/powerpc/kernel/of_device.c
@@ -72,16 +72,47 @@ void of_dev_put(struct of_device *dev)
 		put_device(&dev->dev);
 }
 
-static ssize_t dev_show_devspec(struct device *dev,
+static ssize_t devspec_show(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	struct of_device *ofdev;
 
 	ofdev = to_of_device(dev);
-	return sprintf(buf, "%s", ofdev->node->full_name);
+	return sprintf(buf, "%s\n", ofdev->node->full_name);
 }
 
-static DEVICE_ATTR(devspec, S_IRUGO, dev_show_devspec, NULL);
+static ssize_t modalias_show (struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	struct of_device *ofdev;
+	const char *compat;
+	int cplen;
+	int length;
+
+	ofdev = to_of_device(dev);
+	compat = get_property(ofdev->node, "compatible", &cplen);
+	if (!compat) compat = "", cplen = 1;
+	length = sprintf (buf, "of:N%sT%s", ofdev->node->name, ofdev->node->type);
+	buf += length;
+	while (cplen > 0) {
+		int l;
+		l = sprintf (buf, "C%s", compat);
+		length += l;
+		buf += l;
+		l = strlen (compat) + 1;
+		compat += l;
+		cplen -= l;
+	}
+	length += sprintf (buf, "\n");
+
+	return length;
+}
+
+struct device_attribute of_platform_device_attrs[] = {
+	__ATTR_RO(devspec),
+	__ATTR_RO(modalias),
+	__ATTR_NULL
+};
 
 /**
  * of_release_dev - free an of device structure when all users of it are finished.
@@ -101,21 +132,13 @@ void of_release_dev(struct device *dev)
 
 int of_device_register(struct of_device *ofdev)
 {
-	int rc;
-
 	BUG_ON(ofdev->node == NULL);
 
-	rc = device_register(&ofdev->dev);
-	if (rc)
-		return rc;
-
-	return device_create_file(&ofdev->dev, &dev_attr_devspec);
+	return device_register(&ofdev->dev);
 }
 
 void of_device_unregister(struct of_device *ofdev)
 {
-	device_remove_file(&ofdev->dev, &dev_attr_devspec);
-
 	device_unregister(&ofdev->dev);
 }
 
Index: b/arch/powerpc/kernel/of_platform.c
===================================================================
--- a/arch/powerpc/kernel/of_platform.c
+++ b/arch/powerpc/kernel/of_platform.c
@@ -130,6 +130,8 @@ static int of_platform_device_resume(str
 	return error;
 }
 
+extern struct device_attribute of_platform_device_attrs[];
+
 struct bus_type of_platform_bus_type = {
        .name	= "of_platform",
        .match	= of_platform_bus_match,
@@ -137,6 +139,7 @@ struct bus_type of_platform_bus_type = {
        .remove	= of_platform_device_remove,
        .suspend	= of_platform_device_suspend,
        .resume	= of_platform_device_resume,
+       .dev_attrs = of_platform_device_attrs,
 };
 EXPORT_SYMBOL(of_platform_bus_type);