PM / wakeup: Register wakeup class kobj after device is added

The device_set_wakeup_enable() function can be called on a device that
hasn't been registered with device_add() yet. This allows the device to
be in a state where wakeup is enabled for it but the device isn't
published to userspace in sysfs yet.

After commit c8377adfa7 ("PM / wakeup: Show wakeup sources stats in
sysfs"), calling device_set_wakeup_enable() will fail for a device that
hasn't been registered with the driver core via device_add(). This is
because we try to create sysfs entries for the device and associate a
wakeup class kobject with it before the device has been registered.
Let's follow a similar approach that device_set_wakeup_capable() takes
here and register the wakeup class either from
device_set_wakeup_enable() when the device is already registered, or
from dpm_sysfs_add() when the device is being registered with the driver
core via device_add().

Fixes: c8377adfa7 ("PM / wakeup: Show wakeup sources stats in sysfs")
Reported-by: Qian Cai <cai@lca.pw>
Reviewed-by: Tri Vo <trong@android.com>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/power.h

@@ -157,4 +157,13 @@ extern int wakeup_source_sysfs_add(struct device *parent,
 				   struct wakeup_source *ws);
 extern void wakeup_source_sysfs_remove(struct wakeup_source *ws);
 
+extern int pm_wakeup_source_sysfs_add(struct device *parent);
+
+#else /* !CONFIG_PM_SLEEP */
+
+static inline int pm_wakeup_source_sysfs_add(struct device *parent)
+{
+	return 0;
+}
+
 #endif /* CONFIG_PM_SLEEP */

drivers/base/power/sysfs.c

@@ -5,6 +5,7 @@
 #include <linux/export.h>
 #include <linux/pm_qos.h>
 #include <linux/pm_runtime.h>
+#include <linux/pm_wakeup.h>
 #include <linux/atomic.h>
 #include <linux/jiffies.h>
 #include "power.h"
@@ -667,8 +668,13 @@ int dpm_sysfs_add(struct device *dev)
 		if (rc)
 			goto err_wakeup;
 	}
+	rc = pm_wakeup_source_sysfs_add(dev);
+	if (rc)
+		goto err_latency;
 	return 0;
 
+ err_latency:
+	sysfs_unmerge_group(&dev->kobj, &pm_qos_latency_tolerance_attr_group);
  err_wakeup:
 	sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
  err_runtime:

drivers/base/power/wakeup.c

@@ -220,11 +220,13 @@ struct wakeup_source *wakeup_source_register(struct device *dev,
 
 	ws = wakeup_source_create(name);
 	if (ws) {
+		if (!dev || device_is_registered(dev)) {
 			ret = wakeup_source_sysfs_add(dev, ws);
 			if (ret) {
 				wakeup_source_free(ws);
 				return NULL;
 			}
+		}
 		wakeup_source_add(ws);
 	}
 	return ws;

drivers/base/power/wakeup_stats.c

@@ -184,6 +184,19 @@ int wakeup_source_sysfs_add(struct device *parent, struct wakeup_source *ws)
 }
 EXPORT_SYMBOL_GPL(wakeup_source_sysfs_add);
 
+/**
+ * pm_wakeup_source_sysfs_add - Add wakeup_source attributes to sysfs
+ * for a device if they're missing.
+ * @parent: Device given wakeup source is associated with
+ */
+int pm_wakeup_source_sysfs_add(struct device *parent)
+{
+	if (!parent->power.wakeup || parent->power.wakeup->dev)
+		return 0;
+
+	return wakeup_source_sysfs_add(parent, parent->power.wakeup);
+}
+
 /**
  * wakeup_source_sysfs_remove - Remove wakeup_source attributes from sysfs.
  * @ws: Wakeup source to be removed from sysfs.