[PATCH v5 4/9] OF: platform: Add OF notifier handler

[Pantelis Antoniou]

Add OF notifier handler needed for creating/destroying platform devices
according to dynamic runtime changes in the DT live tree.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
---
 drivers/base/platform.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 66 insertions(+), 3 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 9e9227e..8d64605 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -930,6 +930,56 @@ struct bus_type platform_bus_type = {
 };
 EXPORT_SYMBOL_GPL(platform_bus_type);
 
+static struct notifier_block platform_of_notifier;
+
+static int of_platform_notify(struct notifier_block *nb,
+				unsigned long action, void *arg)
+{
+	struct device_node *dn;
+	struct platform_device *pdev_parent, *pdev;
+
+	if (action == OF_RECONFIG_DYNAMIC_CREATE_DEV) {
+
+		dn = arg;
+
+		/* verify that the parent is a bus */
+		if (!of_match_node(of_default_bus_match_table, dn->parent))
+			return NOTIFY_OK;	/* not for us */
+
+		/* pdev_parent may be NULL when no bus platform device */
+		pdev_parent = of_find_device_by_node(dn->parent);
+		pdev = of_platform_device_create(dn, NULL,
+				pdev_parent ? &pdev_parent->dev : NULL);
+		of_dev_put(pdev_parent);
+
+		if (pdev == NULL) {
+			pr_err("%s: failed to create for '%s'\n",
+					__func__, dn->full_name);
+			/* of_platform_device_create tosses the error code */
+			return notifier_from_errno(-EINVAL);
+		}
+
+	} else if (action == OF_RECONFIG_DYNAMIC_DESTROY_DEV) {
+
+		dn = arg;
+
+		/* find our device by node */
+		pdev = of_find_device_by_node(dn);
+		if (pdev == NULL)
+			return NOTIFY_OK;	/* no? not meant for us */
+
+		/* unregister takes one ref away */
+		platform_device_unregister(pdev);
+
+		/* and put the reference of the find */
+		of_dev_put(pdev);
+
+	} else
+		return NOTIFY_OK;
+
+	return NOTIFY_STOP;
+}
+
 int __init platform_bus_init(void)
 {
 	int error;
@@ -938,10 +988,23 @@ int __init platform_bus_init(void)
 
 	error = device_register(&platform_bus);
 	if (error)
-		return error;
-	error =  bus_register(&platform_bus_type);
+		goto err_out;
+
+	error = bus_register(&platform_bus_type);
+	if (error)
+		goto err_unreg_dev;
+
+	platform_of_notifier.notifier_call = of_platform_notify;
+	error = of_reconfig_notifier_register(&platform_of_notifier);
 	if (error)
-		device_unregister(&platform_bus);
+		goto err_unreg_bus;
+
+	return 0;
+err_unreg_bus:
+	bus_unregister(&platform_bus_type);
+err_unreg_dev:
+	device_unregister(&platform_bus);
+err_out:
 	return error;
 }
 
-- 
1.7.12

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