facility is inherently dangerous, it is disabled by default
for all devices except hubs. For more information, see
Documentation/usb/persist.txt.
+
+What: /sys/bus/usb/device/.../power/connected_duration
+Date: January 2008
+KernelVersion: 2.6.25
+Contact: Sarah Sharp <sarah.a.sharp@intel.com>
+Description:
+ If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file
+ is present. When read, it returns the total time (in msec)
+ that the USB device has been connected to the machine. This
+ file is read-only.
+Users:
+ PowerTOP <power@bughost.org>
+ http://www.lesswatts.org/projects/powertop/
+
+What: /sys/bus/usb/device/.../power/active_duration
+Date: January 2008
+KernelVersion: 2.6.25
+Contact: Sarah Sharp <sarah.a.sharp@intel.com>
+Description:
+ If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file
+ is present. When read, it returns the total time (in msec)
+ that the USB device has been active, i.e. not in a suspended
+ state. This file is read-only.
+
+ Tools can use this file and the connected_duration file to
+ compute the percentage of time that a device has been active.
+ For example,
+ echo $((100 * `cat active_duration` / `cat connected_duration`))
+ will give an integer percentage. Note that this does not
+ account for counter wrap.
+Users:
+ PowerTOP <power@bughost.org>
+ http://www.lesswatts.org/projects/powertop/
+
+What: /sys/bus/usb/device/<busnum>-<devnum>...:<config num>-<interface num>/supports_autosuspend
+Date: January 2008
+KernelVersion: 2.6.27
+Contact: Sarah Sharp <sarah.a.sharp@intel.com>
+Description:
+ When read, this file returns 1 if the interface driver
+ for this interface supports autosuspend. It also
+ returns 1 if no driver has claimed this interface, as an
+ unclaimed interface will not stop the device from being
+ autosuspended if all other interface drivers are idle.
+ The file returns 0 if autosuspend support has not been
+ added to the driver.
+Users:
+ USB PM tool
+ git://git.moblin.org/users/sarah/usb-pm-tool/
+
+What: /sys/bus/usb/device/.../authorized
+Date: July 2008
+KernelVersion: 2.6.26
+Contact: David Vrabel <david.vrabel@csr.com>
+Description:
+ Authorized devices are available for use by device
+ drivers, non-authorized one are not. By default, wired
+ USB devices are authorized.
+
+ Certified Wireless USB devices are not authorized
+ initially and should be (by writing 1) after the
+ device has been authenticated.
+
+What: /sys/bus/usb/device/.../wusb_cdid
+Date: July 2008
+KernelVersion: 2.6.27
+Contact: David Vrabel <david.vrabel@csr.com>
+Description:
+ For Certified Wireless USB devices only.
+
+ A devices's CDID, as 16 space-separated hex octets.
+
+What: /sys/bus/usb/device/.../wusb_ck
+Date: July 2008
+KernelVersion: 2.6.27
+Contact: David Vrabel <david.vrabel@csr.com>
+Description:
+ For Certified Wireless USB devices only.
+
+ Write the device's connection key (CK) to start the
+ authentication of the device. The CK is 16
+ space-separated hex octets.
+
+What: /sys/bus/usb/device/.../wusb_disconnect
+Date: July 2008
+KernelVersion: 2.6.27
+Contact: David Vrabel <david.vrabel@csr.com>
+Description:
+ For Certified Wireless USB devices only.
+
+ Write a 1 to force the device to disconnect
+ (equivalent to unplugging a wired USB device).