USB: separate autosuspend from external suspend

This patch (as866) adds new entry points for external USB device
suspend and resume requests, as opposed to internally-generated
autosuspend or autoresume.  It also changes the existing
remote-wakeup code paths to use the new routines, since remote wakeup
is not the same as autoresume.

As part of the change, it turns out to be necessary to do remote
wakeup of root hubs from a workqueue.  We had been using khubd, but it
does autoresume rather than an external resume.  Using the
ksuspend_usb_wq workqueue for this purpose seemed a logical choice.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 59 insertions, 23 deletions

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 8c0a7de6122..abea48de876 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1424,48 +1424,84 @@ void usb_autosuspend_work(struct work_struct *work)
 
 #endif /* CONFIG_USB_SUSPEND */
 
-static int usb_suspend(struct device *dev, pm_message_t message)
+/**
+ * usb_external_suspend_device - external suspend of a USB device and its interfaces
+ * @udev: the usb_device to suspend
+ * @msg: Power Management message describing this state transition
+ *
+ * This routine handles external suspend requests: ones not generated
+ * internally by a USB driver (autosuspend) but rather coming from the user
+ * (via sysfs) or the PM core (system sleep).  The suspend will be carried
+ * out regardless of @udev's usage counter or those of its interfaces,
+ * and regardless of whether or not remote wakeup is enabled.  Of course,
+ * interface drivers still have the option of failing the suspend (if
+ * there are unsuspended children, for example).
+ *
+ * The caller must hold @udev's device lock.
+ */
+int usb_external_suspend_device(struct usb_device *udev, pm_message_t msg)
 {
 	int	status;
 
-	if (is_usb_device(dev)) {
-		struct usb_device *udev = to_usb_device(dev);
-
-		usb_pm_lock(udev);
-		udev->auto_pm = 0;
-		status = usb_suspend_both(udev, message);
-		usb_pm_unlock(udev);
-	} else
-		status = 0;
+	usb_pm_lock(udev);
+	udev->auto_pm = 0;
+	status = usb_suspend_both(udev, msg);
+	usb_pm_unlock(udev);
 	return status;
 }
 
-static int usb_resume(struct device *dev)
+/**
+ * usb_external_resume_device - external resume of a USB device and its interfaces
+ * @udev: the usb_device to resume
+ *
+ * This routine handles external resume requests: ones not generated
+ * internally by a USB driver (autoresume) but rather coming from the user
+ * (via sysfs), the PM core (system resume), or the device itself (remote
+ * wakeup).  @udev's usage counter is unaffected.
+ *
+ * The caller must hold @udev's device lock.
+ */
+int usb_external_resume_device(struct usb_device *udev)
 {
 	int	status;
 
-	if (is_usb_device(dev)) {
-		struct usb_device *udev = to_usb_device(dev);
-
-		usb_pm_lock(udev);
-		udev->auto_pm = 0;
-		status = usb_resume_both(udev);
-		usb_pm_unlock(udev);
+	usb_pm_lock(udev);
+	udev->auto_pm = 0;
+	status = usb_resume_both(udev);
+	usb_pm_unlock(udev);
 
-		/* Rebind drivers that had no suspend method? */
-	} else
-		status = 0;
+	/* Now that the device is awake, we can start trying to autosuspend
+	 * it again. */
+	if (status == 0)
+		usb_try_autosuspend_device(udev);
 	return status;
 }
 
+static int usb_suspend(struct device *dev, pm_message_t message)
+{
+	if (!is_usb_device(dev))	/* Ignore PM for interfaces */
+		return 0;
+	return usb_external_suspend_device(to_usb_device(dev), message);
+}
+
+static int usb_resume(struct device *dev)
+{
+	if (!is_usb_device(dev))	/* Ignore PM for interfaces */
+		return 0;
+	return usb_external_resume_device(to_usb_device(dev));
+}
+
+#else
+
+#define usb_suspend	NULL
+#define usb_resume	NULL
+
 #endif /* CONFIG_PM */
 
 struct bus_type usb_bus_type = {
 	.name =		"usb",
 	.match =	usb_device_match,
 	.uevent =	usb_uevent,
-#ifdef CONFIG_PM
 	.suspend =	usb_suspend,
 	.resume =	usb_resume,
-#endif
 };