Documentation/ABI/testing/sysfs-bus-usb

   1 What:           /sys/bus/usb/devices/INTERFACE/authorized
   2 Date:           August 2015
   3 Description:
   4                 This allows to authorize (1) or deauthorize (0)
   5                 individual interfaces instead a whole device
   6                 in contrast to the device authorization.
   7                 If a deauthorized interface will be authorized
   8                 so the driver probing must be triggered manually
   9                 by writing INTERFACE to /sys/bus/usb/drivers_probe
  10                 This allows to avoid side-effects with drivers
  11                 that need multiple interfaces.
  12                 A deauthorized interface cannot be probed or claimed.
  13
  14 What:           /sys/bus/usb/devices/usbX/interface_authorized_default
  15 Date:           August 2015
  16 Description:
  17                 This is used as value that determines if interfaces
  18                 would be authorized by default.
  19                 The value can be 1 or 0. It's by default 1.
  20
  21 What:           /sys/bus/usb/device/.../authorized
  22 Date:           July 2008
  23 KernelVersion:  2.6.26
  24 Contact:        David Vrabel <david.vrabel@csr.com>
  25 Description:
  26                 Authorized devices are available for use by device
  27                 drivers, non-authorized one are not.  By default, wired
  28                 USB devices are authorized.
  29
  30                 Certified Wireless USB devices are not authorized
  31                 initially and should be (by writing 1) after the
  32                 device has been authenticated.
  33
  34 What:           /sys/bus/usb/device/.../wusb_cdid
  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                 A devices's CDID, as 16 space-separated hex octets.
  42
  43 What:           /sys/bus/usb/device/.../wusb_ck
  44 Date:           July 2008
  45 KernelVersion:  2.6.27
  46 Contact:        David Vrabel <david.vrabel@csr.com>
  47 Description:
  48                 For Certified Wireless USB devices only.
  49
  50                 Write the device's connection key (CK) to start the
  51                 authentication of the device.  The CK is 16
  52                 space-separated hex octets.
  53
  54 What:           /sys/bus/usb/device/.../wusb_disconnect
  55 Date:           July 2008
  56 KernelVersion:  2.6.27
  57 Contact:        David Vrabel <david.vrabel@csr.com>
  58 Description:
  59                 For Certified Wireless USB devices only.
  60
  61                 Write a 1 to force the device to disconnect
  62                 (equivalent to unplugging a wired USB device).
  63
  64 What:           /sys/bus/usb/drivers/.../new_id
  65 Date:           October 2011
  66 Contact:        linux-usb@vger.kernel.org
  67 Description:
  68                 Writing a device ID to this file will attempt to
  69                 dynamically add a new device ID to a USB device driver.
  70                 This may allow the driver to support more hardware than
  71                 was included in the driver's static device ID support
  72                 table at compile time. The format for the device ID is:
  73                 idVendor idProduct bInterfaceClass RefIdVendor RefIdProduct
  74                 The vendor ID and device ID fields are required, the
  75                 rest is optional. The Ref* tuple can be used to tell the
  76                 driver to use the same driver_data for the new device as
  77                 it is used for the reference device.
  78                 Upon successfully adding an ID, the driver will probe
  79                 for the device and attempt to bind to it.  For example:
  80                 # echo "8086 10f5" > /sys/bus/usb/drivers/foo/new_id
  81
  82                 Here add a new device (0458:7045) using driver_data from
  83                 an already supported device (0458:704c):
  84                 # echo "0458 7045 0 0458 704c" > /sys/bus/usb/drivers/foo/new_id
  85
  86                 Reading from this file will list all dynamically added
  87                 device IDs in the same format, with one entry per
  88                 line. For example:
  89                 # cat /sys/bus/usb/drivers/foo/new_id
  90                 8086 10f5
  91                 dead beef 06
  92                 f00d cafe
  93
  94                 The list will be truncated at PAGE_SIZE bytes due to
  95                 sysfs restrictions.
  96
  97 What:           /sys/bus/usb-serial/drivers/.../new_id
  98 Date:           October 2011
  99 Contact:        linux-usb@vger.kernel.org
 100 Description:
 101                 For serial USB drivers, this attribute appears under the
 102                 extra bus folder "usb-serial" in sysfs; apart from that
 103                 difference, all descriptions from the entry
 104                 "/sys/bus/usb/drivers/.../new_id" apply.
 105
 106 What:           /sys/bus/usb/drivers/.../remove_id
 107 Date:           November 2009
 108 Contact:        CHENG Renquan <rqcheng@smu.edu.sg>
 109 Description:
 110                 Writing a device ID to this file will remove an ID
 111                 that was dynamically added via the new_id sysfs entry.
 112                 The format for the device ID is:
 113                 idVendor idProduct.     After successfully
 114                 removing an ID, the driver will no longer support the
 115                 device.  This is useful to ensure auto probing won't
 116                 match the driver to the device.  For example:
 117                 # echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id
 118
 119                 Reading from this file will list the dynamically added
 120                 device IDs, exactly like reading from the entry
 121                 "/sys/bus/usb/drivers/.../new_id"
 122
 123 What:           /sys/bus/usb/devices/.../power/usb2_hardware_lpm
 124 Date:           September 2011
 125 Contact:        Andiry Xu <andiry.xu@amd.com>
 126 Description:
 127                 If CONFIG_PM is set and a USB 2.0 lpm-capable device is plugged
 128                 in to a xHCI host which support link PM, it will perform a LPM
 129                 test; if the test is passed and host supports USB2 hardware LPM
 130                 (xHCI 1.0 feature), USB2 hardware LPM will be enabled for the
 131                 device and the USB device directory will contain a file named
 132                 power/usb2_hardware_lpm.  The file holds a string value (enable
 133                 or disable) indicating whether or not USB2 hardware LPM is
 134                 enabled for the device. Developer can write y/Y/1 or n/N/0 to
 135                 the file to enable/disable the feature.
 136
 137 What:           /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u1
 138                 /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u2
 139 Date:           November 2015
 140 Contact:        Kevin Strasser <kevin.strasser@linux.intel.com>
 141                 Lu Baolu <baolu.lu@linux.intel.com>
 142 Description:
 143                 If CONFIG_PM is set and a USB 3.0 lpm-capable device is plugged
 144                 in to a xHCI host which supports link PM, it will check if U1
 145                 and U2 exit latencies have been set in the BOS descriptor; if
 146                 the check is passed and the host supports USB3 hardware LPM,
 147                 USB3 hardware LPM will be enabled for the device and the USB
 148                 device directory will contain two files named
 149                 power/usb3_hardware_lpm_u1 and power/usb3_hardware_lpm_u2. These
 150                 files hold a string value (enable or disable) indicating whether
 151                 or not USB3 hardware LPM U1 or U2 is enabled for the device.
 152
 153 What:           /sys/bus/usb/devices/.../removable
 154 Date:           February 2012
 155 Contact:        Matthew Garrett <mjg@redhat.com>
 156 Description:
 157                 Some information about whether a given USB device is
 158                 physically fixed to the platform can be inferred from a
 159                 combination of hub descriptor bits and platform-specific data
 160                 such as ACPI. This file will read either "removable" or
 161                 "fixed" if the information is available, and "unknown"
 162                 otherwise.
 163
 164 What:           /sys/bus/usb/devices/.../ltm_capable
 165 Date:           July 2012
 166 Contact:        Sarah Sharp <sarah.a.sharp@linux.intel.com>
 167 Description:
 168                 USB 3.0 devices may optionally support Latency Tolerance
 169                 Messaging (LTM).  They indicate their support by setting a bit
 170                 in the bmAttributes field of their SuperSpeed BOS descriptors.
 171                 If that bit is set for the device, ltm_capable will read "yes".
 172                 If the device doesn't support LTM, the file will read "no".
 173                 The file will be present for all speeds of USB devices, and will
 174                 always read "no" for USB 1.1 and USB 2.0 devices.
 175
 176 What:           /sys/bus/usb/devices/.../(hub interface)/portX
 177 Date:           August 2012
 178 Contact:        Lan Tianyu <tianyu.lan@intel.com>
 179 Description:
 180                 The /sys/bus/usb/devices/.../(hub interface)/portX
 181                 is usb port device's sysfs directory.
 182
 183 What:           /sys/bus/usb/devices/.../(hub interface)/portX/connect_type
 184 Date:           January 2013
 185 Contact:        Lan Tianyu <tianyu.lan@intel.com>
 186 Description:
 187                 Some platforms provide usb port connect types through ACPI.
 188                 This attribute is to expose these information to user space.
 189                 The file will read "hotplug", "wired" and "not used" if the
 190                 information is available, and "unknown" otherwise.
 191
 192 What:           /sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit
 193 Date:           November 2015
 194 Contact:        Lu Baolu <baolu.lu@linux.intel.com>
 195 Description:
 196                 Some USB3.0 devices are not friendly to USB3 LPM.  usb3_lpm_permit
 197                 attribute allows enabling/disabling usb3 lpm of a port. It takes
 198                 effect both before and after a usb device is enumerated. Supported
 199                 values are "0" if both u1 and u2 are NOT permitted, "u1" if only u1
 200                 is permitted, "u2" if only u2 is permitted, "u1_u2" if both u1 and
 201                 u2 are permitted.
 202
 203 What:           /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
 204 Date:           May 2013
 205 Contact:        Mathias Nyman <mathias.nyman@linux.intel.com>
 206 Description:
 207                 USB 2.0 devices may support hardware link power management (LPM)
 208                 L1 sleep state. The usb2_lpm_l1_timeout attribute allows
 209                 tuning the timeout for L1 inactivity timer (LPM timer), e.g.
 210                 needed inactivity time before host requests the device to go to L1 sleep.
 211                 Useful for power management tuning.
 212                 Supported values are 0 - 65535 microseconds.
 213
 214 What:           /sys/bus/usb/devices/.../power/usb2_lpm_besl
 215 Date:           May 2013
 216 Contact:        Mathias Nyman <mathias.nyman@linux.intel.com>
 217 Description:
 218                 USB 2.0 devices that support hardware link power management (LPM)
 219                 L1 sleep state now use a best effort service latency value (BESL) to
 220                 indicate the best effort to resumption of service to the device after the
 221                 initiation of the resume event.
 222                 If the device does not have a preferred besl value then the host can select
 223                 one instead. This usb2_lpm_besl attribute allows to tune the host selected besl
 224                 value in order to tune power saving and service latency.
 225
 226                 Supported values are 0 - 15.
 227                 More information on how besl values map to microseconds can be found in
 228                 USB 2.0 ECN Errata for Link Power Management, section 4.10)