USB: Export suspend statistics

This patch exports two statistics to userspace:
/sys/bus/usb/device/.../power/connected_duration
/sys/bus/usb/device/.../power/active_duration

connected_duration is the total time (in msec) that the device has
been connected.  active_duration is the total time the device has not
been suspended.  With these two statistics, tools like PowerTOP can
calculate the percentage time that a device is active, i.e. not
suspended or auto-suspended.

Users can also use the active_duration to check if a device is actually
autosuspended.  Currently, they can set power/level to auto and
power/autosuspend to a positive timeout, but there's no way to know from
userspace if a device was actually autosuspended without looking at the
dmesg output.  These statistics will be useful in creating an automated
userspace script to test autosuspend for USB devices.

Signed-off-by: Sarah Sharp <sarah.a.sharp@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 9 insertions, 1 deletions

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index cc93aa9336fe..53fe049b40f5 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1034,8 +1034,10 @@ static void recursively_mark_NOTATTACHED(struct usb_device *udev)
 		if (udev->children[i])
 			recursively_mark_NOTATTACHED(udev->children[i]);
 	}
-	if (udev->state == USB_STATE_SUSPENDED)
+	if (udev->state == USB_STATE_SUSPENDED) {
 		udev->discon_suspended = 1;
+		udev->active_duration -= jiffies;
+	}
 	udev->state = USB_STATE_NOTATTACHED;
 }
 
@@ -1084,6 +1086,12 @@ void usb_set_device_state(struct usb_device *udev,
 			else
 				device_init_wakeup(&udev->dev, 0);
 		}
+		if (udev->state == USB_STATE_SUSPENDED &&
+			new_state != USB_STATE_SUSPENDED)
+			udev->active_duration -= jiffies;
+		else if (new_state == USB_STATE_SUSPENDED &&
+				udev->state != USB_STATE_SUSPENDED)
+			udev->active_duration += jiffies;
 		udev->state = new_state;
 	} else
 		recursively_mark_NOTATTACHED(udev);