usbcore: add autosuspend/autoresume infrastructure

This patch (as739) adds the basic infrastructure for USB autosuspend
and autoresume.  The main features are:

	PM usage counters added to struct usb_device and struct
	usb_interface, indicating whether it's okay to autosuspend
	them or they are currently in use.

	Flag added to usb_device indicating whether the current
	suspend/resume operation originated from outside or as an
	autosuspend/autoresume.

	Flag added to usb_driver indicating whether the driver
	supports autosuspend.  If not, no device bound to the driver
	will be autosuspended.

	Mutex added to usb_device for protecting PM operations.
	Unlike the device semaphore, the locking rule for the pm_mutex
	is that you must acquire the locks going _up_ the device tree.

	New routines handling autosuspend/autoresume requests for
	interfaces and devices.

	Suspend and resume requests are propagated up the device tree
	(but not outside the USB subsystem).

	work_struct added to usb_device, for carrying out delayed
	autosuspend requests.

	Autoresume added (and autosuspend prevented) during probe and
	disconnect.

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

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index b0c0a993338f..6b029cdb8671 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -168,6 +168,10 @@ static void usb_release_dev(struct device *dev)
 
         udev = to_usb_device(dev);
 
+#ifdef  CONFIG_PM
+        cancel_delayed_work(&udev->autosuspend);
+        flush_scheduled_work();
+#endif
         usb_destroy_configuration(udev);
         usb_put_hcd(bus_to_hcd(udev->bus));
         kfree(udev->product);
@@ -176,6 +180,21 @@ static void usb_release_dev(struct device *dev)
         kfree(udev);
 }
 
+#ifdef  CONFIG_PM
+
+/* usb_autosuspend_work - callback routine to autosuspend a USB device */
+static void usb_autosuspend_work(void *_udev)
+{
+        struct usb_device       *udev = _udev;
+
+        mutex_lock_nested(&udev->pm_mutex, udev->level);
+        udev->auto_pm = 1;
+        usb_suspend_both(udev, PMSG_SUSPEND);
+        mutex_unlock(&udev->pm_mutex);
+}
+
+#endif
+
 /**
  * usb_alloc_dev - usb device constructor (usbcore-internal)
  * @parent: hub to which device is connected; null to allocate a root hub
@@ -251,6 +270,10 @@ usb_alloc_dev(struct usb_device *parent, struct usb_bus *bus, unsigned port1)
         dev->parent = parent;
         INIT_LIST_HEAD(&dev->filelist);
 
+#ifdef  CONFIG_PM
+        mutex_init(&dev->pm_mutex);
+        INIT_WORK(&dev->autosuspend, usb_autosuspend_work, dev);
+#endif
         return dev;
 }