Documentation/ABI/testing/sysfs-bus-usb

   1 What:           /sys/bus/usb/device/.../authorized
   2 Date:           July 2008
   3 KernelVersion:  2.6.26
   4 Contact:        David Vrabel <david.vrabel@csr.com>
   5 Description:
   6                 Authorized devices are available for use by device
   7                 drivers, non-authorized one are not.  By default, wired
   8                 USB devices are authorized.
   9
  10                 Certified Wireless USB devices are not authorized
  11                 initially and should be (by writing 1) after the
  12                 device has been authenticated.
  13
  14 What:           /sys/bus/usb/device/.../wusb_cdid
  15 Date:           July 2008
  16 KernelVersion:  2.6.27
  17 Contact:        David Vrabel <david.vrabel@csr.com>
  18 Description:
  19                 For Certified Wireless USB devices only.
  20
  21                 A devices's CDID, as 16 space-separated hex octets.
  22
  23 What:           /sys/bus/usb/device/.../wusb_ck
  24 Date:           July 2008
  25 KernelVersion:  2.6.27
  26 Contact:        David Vrabel <david.vrabel@csr.com>
  27 Description:
  28                 For Certified Wireless USB devices only.
  29
  30                 Write the device's connection key (CK) to start the
  31                 authentication of the device.  The CK is 16
  32                 space-separated hex octets.
  33
  34 What:           /sys/bus/usb/device/.../wusb_disconnect
  35 Date:           July 2008
  36 KernelVersion:  2.6.27
  37 Contact:        David Vrabel <david.vrabel@csr.com>
  38 Description:
  39                 For Certified Wireless USB devices only.
  40
  41                 Write a 1 to force the device to disconnect
  42                 (equivalent to unplugging a wired USB device).
  43
  44 What:           /sys/bus/usb/drivers/.../new_id
  45 Date:           October 2011
  46 Contact:        linux-usb@vger.kernel.org
  47 Description:
  48                 Writing a device ID to this file will attempt to
  49                 dynamically add a new device ID to a USB device driver.
  50                 This may allow the driver to support more hardware than
  51                 was included in the driver's static device ID support
  52                 table at compile time. The format for the device ID is:
  53                 idVendor idProduct bInterfaceClass RefIdVendor RefIdProduct
  54                 The vendor ID and device ID fields are required, the
  55                 rest is optional. The Ref* tuple can be used to tell the
  56                 driver to use the same driver_data for the new device as
  57                 it is used for the reference device.
  58                 Upon successfully adding an ID, the driver will probe
  59                 for the device and attempt to bind to it.  For example:
  60                 # echo "8086 10f5" > /sys/bus/usb/drivers/foo/new_id
  61
  62                 Here add a new device (0458:7045) using driver_data from
  63                 an already supported device (0458:704c):
  64                 # echo "0458 7045 0 0458 704c" > /sys/bus/usb/drivers/foo/new_id
  65
  66                 Reading from this file will list all dynamically added
  67                 device IDs in the same format, with one entry per
  68                 line. For example:
  69                 # cat /sys/bus/usb/drivers/foo/new_id
  70                 8086 10f5
  71                 dead beef 06
  72                 f00d cafe
  73
  74                 The list will be truncated at PAGE_SIZE bytes due to
  75                 sysfs restrictions.
  76
  77 What:           /sys/bus/usb-serial/drivers/.../new_id
  78 Date:           October 2011
  79 Contact:        linux-usb@vger.kernel.org
  80 Description:
  81                 For serial USB drivers, this attribute appears under the
  82                 extra bus folder "usb-serial" in sysfs; apart from that
  83                 difference, all descriptions from the entry
  84                 "/sys/bus/usb/drivers/.../new_id" apply.
  85
  86 What:           /sys/bus/usb/drivers/.../remove_id
  87 Date:           November 2009
  88 Contact:        CHENG Renquan <rqcheng@smu.edu.sg>
  89 Description:
  90                 Writing a device ID to this file will remove an ID
  91                 that was dynamically added via the new_id sysfs entry.
  92                 The format for the device ID is:
  93                 idVendor idProduct.     After successfully
  94                 removing an ID, the driver will no longer support the
  95                 device.  This is useful to ensure auto probing won't
  96                 match the driver to the device.  For example:
  97                 # echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id
  98
  99                 Reading from this file will list the dynamically added
 100                 device IDs, exactly like reading from the entry
 101                 "/sys/bus/usb/drivers/.../new_id"
 102
 103 What:           /sys/bus/usb/devices/.../power/usb2_hardware_lpm
 104 Date:           September 2011
 105 Contact:        Andiry Xu <andiry.xu@amd.com>
 106 Description:
 107                 If CONFIG_PM is set and a USB 2.0 lpm-capable device is plugged
 108                 in to a xHCI host which support link PM, it will perform a LPM
 109                 test; if the test is passed and host supports USB2 hardware LPM
 110                 (xHCI 1.0 feature), USB2 hardware LPM will be enabled for the
 111                 device and the USB device directory will contain a file named
 112                 power/usb2_hardware_lpm.  The file holds a string value (enable
 113                 or disable) indicating whether or not USB2 hardware LPM is
 114                 enabled for the device. Developer can write y/Y/1 or n/N/0 to
 115                 the file to enable/disable the feature.
 116
 117 What:           /sys/bus/usb/devices/.../power/usb3_hardware_lpm
 118 Date:           June 2015
 119 Contact:        Kevin Strasser <kevin.strasser@linux.intel.com>
 120 Description:
 121                 If CONFIG_PM is set and a USB 3.0 lpm-capable device is plugged
 122                 in to a xHCI host which supports link PM, it will check if U1
 123                 and U2 exit latencies have been set in the BOS descriptor; if
 124                 the check is is passed and the host supports USB3 hardware LPM,
 125                 USB3 hardware LPM will be enabled for the device and the USB
 126                 device directory will contain a file named
 127                 power/usb3_hardware_lpm. The file holds a string value (enable
 128                 or disable) indicating whether or not USB3 hardware LPM is
 129                 enabled for the device.
 130
 131 What:           /sys/bus/usb/devices/.../removable
 132 Date:           February 2012
 133 Contact:        Matthew Garrett <mjg@redhat.com>
 134 Description:
 135                 Some information about whether a given USB device is
 136                 physically fixed to the platform can be inferred from a
 137                 combination of hub descriptor bits and platform-specific data
 138                 such as ACPI. This file will read either "removable" or
 139                 "fixed" if the information is available, and "unknown"
 140                 otherwise.
 141
 142 What:           /sys/bus/usb/devices/.../ltm_capable
 143 Date:           July 2012
 144 Contact:        Sarah Sharp <sarah.a.sharp@linux.intel.com>
 145 Description:
 146                 USB 3.0 devices may optionally support Latency Tolerance
 147                 Messaging (LTM).  They indicate their support by setting a bit
 148                 in the bmAttributes field of their SuperSpeed BOS descriptors.
 149                 If that bit is set for the device, ltm_capable will read "yes".
 150                 If the device doesn't support LTM, the file will read "no".
 151                 The file will be present for all speeds of USB devices, and will
 152                 always read "no" for USB 1.1 and USB 2.0 devices.
 153
 154 What:           /sys/bus/usb/devices/.../(hub interface)/portX
 155 Date:           August 2012
 156 Contact:        Lan Tianyu <tianyu.lan@intel.com>
 157 Description:
 158                 The /sys/bus/usb/devices/.../(hub interface)/portX
 159                 is usb port device's sysfs directory.
 160
 161 What:           /sys/bus/usb/devices/.../(hub interface)/portX/connect_type
 162 Date:           January 2013
 163 Contact:        Lan Tianyu <tianyu.lan@intel.com>
 164 Description:
 165                 Some platforms provide usb port connect types through ACPI.
 166                 This attribute is to expose these information to user space.
 167                 The file will read "hotplug", "wired" and "not used" if the
 168                 information is available, and "unknown" otherwise.
 169
 170 What:           /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
 171 Date:           May 2013
 172 Contact:        Mathias Nyman <mathias.nyman@linux.intel.com>
 173 Description:
 174                 USB 2.0 devices may support hardware link power management (LPM)
 175                 L1 sleep state. The usb2_lpm_l1_timeout attribute allows
 176                 tuning the timeout for L1 inactivity timer (LPM timer), e.g.
 177                 needed inactivity time before host requests the device to go to L1 sleep.
 178                 Useful for power management tuning.
 179                 Supported values are 0 - 65535 microseconds.
 180
 181 What:           /sys/bus/usb/devices/.../power/usb2_lpm_besl
 182 Date:           May 2013
 183 Contact:        Mathias Nyman <mathias.nyman@linux.intel.com>
 184 Description:
 185                 USB 2.0 devices that support hardware link power management (LPM)
 186                 L1 sleep state now use a best effort service latency value (BESL) to
 187                 indicate the best effort to resumption of service to the device after the
 188                 initiation of the resume event.
 189                 If the device does not have a preferred besl value then the host can select
 190                 one instead. This usb2_lpm_besl attribute allows to tune the host selected besl
 191                 value in order to tune power saving and service latency.
 192
 193                 Supported values are 0 - 15.
 194                 More information on how besl values map to microseconds can be found in
 195                 USB 2.0 ECN Errata for Link Power Management, section 4.10)