of/reconfig: Add OF_DYNAMIC notifier for platform_bus_type

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@konsulko.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

3 files changed, 62 insertions, 0 deletions

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index b2afc29403f9..233ececd15a3 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -1006,6 +1006,7 @@ int __init platform_bus_init(void)
         error =  bus_register(&platform_bus_type);
         if (error)
                 device_unregister(&platform_bus);
+        of_platform_register_reconfig_notifier();
         return error;
 }
 
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 656cccf0e680..cd87a36495be 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -550,4 +550,59 @@ void of_platform_depopulate(struct device *parent)
 }
 EXPORT_SYMBOL_GPL(of_platform_depopulate);
 
+#ifdef CONFIG_OF_DYNAMIC
+static int of_platform_notify(struct notifier_block *nb,
+                                unsigned long action, void *arg)
+{
+        struct of_reconfig_data *rd = arg;
+        struct platform_device *pdev_parent, *pdev;
+        bool children_left;
+
+        switch (of_reconfig_get_state_change(action, rd)) {
+        case OF_RECONFIG_CHANGE_ADD:
+                /* verify that the parent is a bus */
+                if (!of_node_check_flag(rd->dn->parent, OF_POPULATED_BUS))
+                        return NOTIFY_OK;       /* not for us */
+
+                /* pdev_parent may be NULL when no bus platform device */
+                pdev_parent = of_find_device_by_node(rd->dn->parent);
+                pdev = of_platform_device_create(rd->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__, rd->dn->full_name);
+                        /* of_platform_device_create tosses the error code */
+                        return notifier_from_errno(-EINVAL);
+                }
+                break;
+
+        case OF_RECONFIG_CHANGE_REMOVE:
+                /* find our device by node */
+                pdev = of_find_device_by_node(rd->dn);
+                if (pdev == NULL)
+                        return NOTIFY_OK;       /* no? not meant for us */
+
+                /* unregister takes one ref away */
+                of_platform_device_destroy(&pdev->dev, &children_left);
+
+                /* and put the reference of the find */
+                of_dev_put(pdev);
+                break;
+        }
+
+        return NOTIFY_OK;
+}
+
+static struct notifier_block platform_of_notifier = {
+        .notifier_call = of_platform_notify,
+};
+
+void of_platform_register_reconfig_notifier(void)
+{
+        WARN_ON(of_reconfig_notifier_register(&platform_of_notifier));
+}
+#endif /* CONFIG_OF_DYNAMIC */
+
 #endif /* CONFIG_OF_ADDRESS */
diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h
index c2b0627a2317..8a860f096c35 100644
--- a/include/linux/of_platform.h
+++ b/include/linux/of_platform.h
@@ -84,4 +84,10 @@ static inline int of_platform_populate(struct device_node *root,
 static inline void of_platform_depopulate(struct device *parent) { }
 #endif
 
+#ifdef CONFIG_OF_DYNAMIC
+extern void of_platform_register_reconfig_notifier(void);
+#else
+static inline void of_platform_register_reconfig_notifier(void) { }
+#endif
+
 #endif  /* _LINUX_OF_PLATFORM_H */