3 files changed, 60 insertions, 1 deletions

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index cc93aa9..53fe049 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);
diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index 32bd130..021b1d3 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -249,6 +249,41 @@ static void remove_persist_attributes(struct device *dev)
 #ifdef	CONFIG_USB_SUSPEND
 
 static ssize_t
+show_connected_duration(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct usb_device *udev = to_usb_device(dev);
+
+	return sprintf(buf, "%u\n",
+			jiffies_to_msecs(jiffies - udev->connect_time));
+}
+
+static DEVICE_ATTR(connected_duration, S_IRUGO, show_connected_duration, NULL);
+
+/*
+ * If the device is resumed, the last time the device was suspended has
+ * been pre-subtracted from active_duration.  We add the current time to
+ * get the duration that the device was actually active.
+ *
+ * If the device is suspended, the active_duration is up-to-date.
+ */
+static ssize_t
+show_active_duration(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct usb_device *udev = to_usb_device(dev);
+	int duration;
+
+	if (udev->state != USB_STATE_SUSPENDED)
+		duration = jiffies_to_msecs(jiffies + udev->active_duration);
+	else
+		duration = jiffies_to_msecs(udev->active_duration);
+	return sprintf(buf, "%u\n", duration);
+}
+
+static DEVICE_ATTR(active_duration, S_IRUGO, show_active_duration, NULL);
+
+static ssize_t
 show_autosuspend(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	struct usb_device *udev = to_usb_device(dev);
@@ -365,6 +400,14 @@ static int add_power_attributes(struct device *dev)
 			rc = sysfs_add_file_to_group(&dev->kobj,
 					&dev_attr_level.attr,
 					power_group);
+		if (rc == 0)
+			rc = sysfs_add_file_to_group(&dev->kobj,
+					&dev_attr_connected_duration.attr,
+					power_group);
+		if (rc == 0)
+			rc = sysfs_add_file_to_group(&dev->kobj,
+					&dev_attr_active_duration.attr,
+					power_group);
 	}
 	return rc;
 }
@@ -372,6 +415,12 @@ static int add_power_attributes(struct device *dev)
 static void remove_power_attributes(struct device *dev)
 {
 	sysfs_remove_file_from_group(&dev->kobj,
+			&dev_attr_active_duration.attr,
+			power_group);
+	sysfs_remove_file_from_group(&dev->kobj,
+			&dev_attr_connected_duration.attr,
+			power_group);
+	sysfs_remove_file_from_group(&dev->kobj,
 			&dev_attr_level.attr,
 			power_group);
 	sysfs_remove_file_from_group(&dev->kobj,
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index bc5edac..fdb444d 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -339,6 +339,8 @@ usb_alloc_dev(struct usb_device *parent, struct usb_bus *bus, unsigned port1)
 	mutex_init(&dev->pm_mutex);
 	INIT_DELAYED_WORK(&dev->autosuspend, usb_autosuspend_work);
 	dev->autosuspend_delay = usb_autosuspend_delay * HZ;
+	dev->connect_time = jiffies;
+	dev->active_duration = -jiffies;
 #endif
 	if (root_hub)	/* Root hub always ok [and always wired] */
 		dev->authorized = 1;