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/persist 18Date: May 2007 19KernelVersion: 2.6.23 20Contact: Alan Stern <stern@rowland.harvard.edu> 21Description: 22 If CONFIG_USB_PERSIST is set, then each USB device directory 23 will contain a file named power/persist. The file holds a 24 boolean value (0 or 1) indicating whether or not the 25 "USB-Persist" facility is enabled for the device. Since the 26 facility is inherently dangerous, it is disabled by default 27 for all devices except hubs. For more information, see 28 Documentation/usb/persist.txt. 29 30What: /sys/bus/usb/device/.../power/connected_duration 31Date: January 2008 32KernelVersion: 2.6.25 33Contact: Sarah Sharp <sarah.a.sharp@intel.com> 34Description: 35 If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file 36 is present. When read, it returns the total time (in msec) 37 that the USB device has been connected to the machine. This 38 file is read-only. 39Users: 40 PowerTOP <power@bughost.org> 41 http://www.lesswatts.org/projects/powertop/ 42 43What: /sys/bus/usb/device/.../power/active_duration 44Date: January 2008 45KernelVersion: 2.6.25 46Contact: Sarah Sharp <sarah.a.sharp@intel.com> 47Description: 48 If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file 49 is present. When read, it returns the total time (in msec) 50 that the USB device has been active, i.e. not in a suspended 51 state. This file is read-only. 52 53 Tools can use this file and the connected_duration file to 54 compute the percentage of time that a device has been active. 55 For example, 56 echo $((100 * `cat active_duration` / `cat connected_duration`)) 57 will give an integer percentage. Note that this does not 58 account for counter wrap. 59Users: 60 PowerTOP <power@bughost.org> 61 http://www.lesswatts.org/projects/powertop/ 62 63What: /sys/bus/usb/device/<busnum>-<devnum>...:<config num>-<interface num>/supports_autosuspend 64Date: January 2008 65KernelVersion: 2.6.27 66Contact: Sarah Sharp <sarah.a.sharp@intel.com> 67Description: 68 When read, this file returns 1 if the interface driver 69 for this interface supports autosuspend. It also 70 returns 1 if no driver has claimed this interface, as an 71 unclaimed interface will not stop the device from being 72 autosuspended if all other interface drivers are idle. 73 The file returns 0 if autosuspend support has not been 74 added to the driver. 75Users: 76 USB PM tool 77 git://git.moblin.org/users/sarah/usb-pm-tool/ 78 79What: /sys/bus/usb/device/.../authorized 80Date: July 2008 81KernelVersion: 2.6.26 82Contact: David Vrabel <david.vrabel@csr.com> 83Description: 84 Authorized devices are available for use by device 85 drivers, non-authorized one are not. By default, wired 86 USB devices are authorized. 87 88 Certified Wireless USB devices are not authorized 89 initially and should be (by writing 1) after the 90 device has been authenticated. 91 92What: /sys/bus/usb/device/.../wusb_cdid 93Date: July 2008 94KernelVersion: 2.6.27 95Contact: David Vrabel <david.vrabel@csr.com> 96Description: 97 For Certified Wireless USB devices only. 98 99 A devices's CDID, as 16 space-separated hex octets. 100 101What: /sys/bus/usb/device/.../wusb_ck 102Date: July 2008 103KernelVersion: 2.6.27 104Contact: David Vrabel <david.vrabel@csr.com> 105Description: 106 For Certified Wireless USB devices only. 107 108 Write the device's connection key (CK) to start the 109 authentication of the device. The CK is 16 110 space-separated hex octets. 111 112What: /sys/bus/usb/device/.../wusb_disconnect 113Date: July 2008 114KernelVersion: 2.6.27 115Contact: David Vrabel <david.vrabel@csr.com> 116Description: 117 For Certified Wireless USB devices only. 118 119 Write a 1 to force the device to disconnect 120 (equivalent to unplugging a wired USB device). 121 122What: /sys/bus/usb/drivers/.../new_id 123Date: October 2011 124Contact: linux-usb@vger.kernel.org 125Description: 126 Writing a device ID to this file will attempt to 127 dynamically add a new device ID to a USB device driver. 128 This may allow the driver to support more hardware than 129 was included in the driver's static device ID support 130 table at compile time. The format for the device ID is: 131 idVendor idProduct bInterfaceClass. 132 The vendor ID and device ID fields are required, the 133 interface class is optional. 134 Upon successfully adding an ID, the driver will probe 135 for the device and attempt to bind to it. For example: 136 # echo "8086 10f5" > /sys/bus/usb/drivers/foo/new_id 137 138 Reading from this file will list all dynamically added 139 device IDs in the same format, with one entry per 140 line. For example: 141 # cat /sys/bus/usb/drivers/foo/new_id 142 8086 10f5 143 dead beef 06 144 f00d cafe 145 146 The list will be truncated at PAGE_SIZE bytes due to 147 sysfs restrictions. 148 149What: /sys/bus/usb-serial/drivers/.../new_id 150Date: October 2011 151Contact: linux-usb@vger.kernel.org 152Description: 153 For serial USB drivers, this attribute appears under the 154 extra bus folder "usb-serial" in sysfs; apart from that 155 difference, all descriptions from the entry 156 "/sys/bus/usb/drivers/.../new_id" apply. 157 158What: /sys/bus/usb/drivers/.../remove_id 159Date: November 2009 160Contact: CHENG Renquan <rqcheng@smu.edu.sg> 161Description: 162 Writing a device ID to this file will remove an ID 163 that was dynamically added via the new_id sysfs entry. 164 The format for the device ID is: 165 idVendor idProduct. After successfully 166 removing an ID, the driver will no longer support the 167 device. This is useful to ensure auto probing won't 168 match the driver to the device. For example: 169 # echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id 170 171 Reading from this file will list the dynamically added 172 device IDs, exactly like reading from the entry 173 "/sys/bus/usb/drivers/.../new_id" 174 175What: /sys/bus/usb/device/.../avoid_reset_quirk 176Date: December 2009 177Contact: Oliver Neukum <oliver@neukum.org> 178Description: 179 Writing 1 to this file tells the kernel that this 180 device will morph into another mode when it is reset. 181 Drivers will not use reset for error handling for 182 such devices. 183Users: 184 usb_modeswitch 185 186What: /sys/bus/usb/devices/.../power/usb2_hardware_lpm 187Date: September 2011 188Contact: Andiry Xu <andiry.xu@amd.com> 189Description: 190 If CONFIG_USB_SUSPEND is set and a USB 2.0 lpm-capable device 191 is plugged in to a xHCI host which support link PM, it will 192 perform a LPM test; if the test is passed and host supports 193 USB2 hardware LPM (xHCI 1.0 feature), USB2 hardware LPM will 194 be enabled for the device and the USB device directory will 195 contain a file named power/usb2_hardware_lpm. The file holds 196 a string value (enable or disable) indicating whether or not 197 USB2 hardware LPM is enabled for the device. Developer can 198 write y/Y/1 or n/N/0 to the file to enable/disable the 199 feature. 200 201What: /sys/bus/usb/devices/.../removable 202Date: February 2012 203Contact: Matthew Garrett <mjg@redhat.com> 204Description: 205 Some information about whether a given USB device is 206 physically fixed to the platform can be inferred from a 207 combination of hub decriptor bits and platform-specific data 208 such as ACPI. This file will read either "removable" or 209 "fixed" if the information is available, and "unknown" 210 otherwise.