1What: /sys/bus/usb/devices/.../power/autosuspend 2Date: March 2007 3KernelVersion: 2.6.21 4Contact: Alan Stern <stern@rowland.harvard.edu> 5Description: 6 Each USB device directory will contain a file named 7 power/autosuspend. This file holds the time (in seconds) 8 the device must be idle before it will be autosuspended. 9 0 means the device will be autosuspended as soon as 10 possible. Negative values will prevent the device from 11 being autosuspended at all, and writing a negative value 12 will resume the device if it is already suspended. 13 14 The autosuspend delay for newly-created devices is set to 15 the value of the usbcore.autosuspend module parameter. 16 17What: /sys/bus/usb/devices/.../power/level 18Date: March 2007 19KernelVersion: 2.6.21 20Contact: Alan Stern <stern@rowland.harvard.edu> 21Description: 22 Each USB device directory will contain a file named 23 power/level. This file holds a power-level setting for 24 the device, one of "on", "auto", or "suspend". 25 26 "on" means that the device is not allowed to autosuspend, 27 although normal suspends for system sleep will still 28 be honored. "auto" means the device will autosuspend 29 and autoresume in the usual manner, according to the 30 capabilities of its driver. "suspend" means the device 31 is forced into a suspended state and it will not autoresume 32 in response to I/O requests. However remote-wakeup requests 33 from the device may still be enabled (the remote-wakeup 34 setting is controlled separately by the power/wakeup 35 attribute). 36 37 During normal use, devices should be left in the "auto" 38 level. The other levels are meant for administrative uses. 39 If you want to suspend a device immediately but leave it 40 free to wake up in response to I/O requests, you should 41 write "0" to power/autosuspend. 42 43What: /sys/bus/usb/devices/.../power/persist 44Date: May 2007 45KernelVersion: 2.6.23 46Contact: Alan Stern <stern@rowland.harvard.edu> 47Description: 48 If CONFIG_USB_PERSIST is set, then each USB device directory 49 will contain a file named power/persist. The file holds a 50 boolean value (0 or 1) indicating whether or not the 51 "USB-Persist" facility is enabled for the device. Since the 52 facility is inherently dangerous, it is disabled by default 53 for all devices except hubs. For more information, see 54 Documentation/usb/persist.txt. 55 56What: /sys/bus/usb/device/.../power/connected_duration 57Date: January 2008 58KernelVersion: 2.6.25 59Contact: Sarah Sharp <sarah.a.sharp@intel.com> 60Description: 61 If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file 62 is present. When read, it returns the total time (in msec) 63 that the USB device has been connected to the machine. This 64 file is read-only. 65Users: 66 PowerTOP <power@bughost.org> 67 http://www.lesswatts.org/projects/powertop/ 68 69What: /sys/bus/usb/device/.../power/active_duration 70Date: January 2008 71KernelVersion: 2.6.25 72Contact: Sarah Sharp <sarah.a.sharp@intel.com> 73Description: 74 If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file 75 is present. When read, it returns the total time (in msec) 76 that the USB device has been active, i.e. not in a suspended 77 state. This file is read-only. 78 79 Tools can use this file and the connected_duration file to 80 compute the percentage of time that a device has been active. 81 For example, 82 echo $((100 * `cat active_duration` / `cat connected_duration`)) 83 will give an integer percentage. Note that this does not 84 account for counter wrap. 85Users: 86 PowerTOP <power@bughost.org> 87 http://www.lesswatts.org/projects/powertop/ 88 89What: /sys/bus/usb/device/<busnum>-<devnum>...:<config num>-<interface num>/supports_autosuspend 90Date: January 2008 91KernelVersion: 2.6.27 92Contact: Sarah Sharp <sarah.a.sharp@intel.com> 93Description: 94 When read, this file returns 1 if the interface driver 95 for this interface supports autosuspend. It also 96 returns 1 if no driver has claimed this interface, as an 97 unclaimed interface will not stop the device from being 98 autosuspended if all other interface drivers are idle. 99 The file returns 0 if autosuspend support has not been 100 added to the driver. 101Users: 102 USB PM tool 103 git://git.moblin.org/users/sarah/usb-pm-tool/ 104 105What: /sys/bus/usb/device/.../authorized 106Date: July 2008 107KernelVersion: 2.6.26 108Contact: David Vrabel <david.vrabel@csr.com> 109Description: 110 Authorized devices are available for use by device 111 drivers, non-authorized one are not. By default, wired 112 USB devices are authorized. 113 114 Certified Wireless USB devices are not authorized 115 initially and should be (by writing 1) after the 116 device has been authenticated. 117 118What: /sys/bus/usb/device/.../wusb_cdid 119Date: July 2008 120KernelVersion: 2.6.27 121Contact: David Vrabel <david.vrabel@csr.com> 122Description: 123 For Certified Wireless USB devices only. 124 125 A devices's CDID, as 16 space-separated hex octets. 126 127What: /sys/bus/usb/device/.../wusb_ck 128Date: July 2008 129KernelVersion: 2.6.27 130Contact: David Vrabel <david.vrabel@csr.com> 131Description: 132 For Certified Wireless USB devices only. 133 134 Write the device's connection key (CK) to start the 135 authentication of the device. The CK is 16 136 space-separated hex octets. 137 138What: /sys/bus/usb/device/.../wusb_disconnect 139Date: July 2008 140KernelVersion: 2.6.27 141Contact: David Vrabel <david.vrabel@csr.com> 142Description: 143 For Certified Wireless USB devices only. 144 145 Write a 1 to force the device to disconnect 146 (equivalent to unplugging a wired USB device). 147