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Diffstat (limited to 'Documentation/ABI/testing/sysfs-bus-usb')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-usb | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb new file mode 100644 index 000000000..08d456e07 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-usb @@ -0,0 +1,278 @@ +What: /sys/bus/usb/devices/INTERFACE/authorized +Date: August 2015 +Description: + This allows to authorize (1) or deauthorize (0) + individual interfaces instead a whole device + in contrast to the device authorization. + If a deauthorized interface will be authorized + so the driver probing must be triggered manually + by writing INTERFACE to /sys/bus/usb/drivers_probe + This allows to avoid side-effects with drivers + that need multiple interfaces. + A deauthorized interface cannot be probed or claimed. + +What: /sys/bus/usb/devices/usbX/interface_authorized_default +Date: August 2015 +Description: + This is used as value that determines if interfaces + would be authorized by default. + The value can be 1 or 0. It's by default 1. + +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). + +What: /sys/bus/usb/drivers/.../new_id +Date: October 2011 +Contact: linux-usb@vger.kernel.org +Description: + Writing a device ID to this file will attempt to + dynamically add a new device ID to a USB device driver. + This may allow the driver to support more hardware than + was included in the driver's static device ID support + table at compile time. The format for the device ID is: + idVendor idProduct bInterfaceClass RefIdVendor RefIdProduct + The vendor ID and device ID fields are required, the + rest is optional. The Ref* tuple can be used to tell the + driver to use the same driver_data for the new device as + it is used for the reference device. + Upon successfully adding an ID, the driver will probe + for the device and attempt to bind to it. For example: + # echo "8086 10f5" > /sys/bus/usb/drivers/foo/new_id + + Here add a new device (0458:7045) using driver_data from + an already supported device (0458:704c): + # echo "0458 7045 0 0458 704c" > /sys/bus/usb/drivers/foo/new_id + + Reading from this file will list all dynamically added + device IDs in the same format, with one entry per + line. For example: + # cat /sys/bus/usb/drivers/foo/new_id + 8086 10f5 + dead beef 06 + f00d cafe + + The list will be truncated at PAGE_SIZE bytes due to + sysfs restrictions. + +What: /sys/bus/usb-serial/drivers/.../new_id +Date: October 2011 +Contact: linux-usb@vger.kernel.org +Description: + For serial USB drivers, this attribute appears under the + extra bus folder "usb-serial" in sysfs; apart from that + difference, all descriptions from the entry + "/sys/bus/usb/drivers/.../new_id" apply. + +What: /sys/bus/usb/drivers/.../remove_id +Date: November 2009 +Contact: CHENG Renquan <rqcheng@smu.edu.sg> +Description: + Writing a device ID to this file will remove an ID + that was dynamically added via the new_id sysfs entry. + The format for the device ID is: + idVendor idProduct. After successfully + removing an ID, the driver will no longer support the + device. This is useful to ensure auto probing won't + match the driver to the device. For example: + # echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id + + Reading from this file will list the dynamically added + device IDs, exactly like reading from the entry + "/sys/bus/usb/drivers/.../new_id" + +What: /sys/bus/usb/devices/.../power/usb2_hardware_lpm +Date: September 2011 +Contact: Andiry Xu <andiry.xu@amd.com> +Description: + If CONFIG_PM is set and a USB 2.0 lpm-capable device is plugged + in to a xHCI host which support link PM, it will perform a LPM + test; if the test is passed and host supports USB2 hardware LPM + (xHCI 1.0 feature), USB2 hardware LPM will be enabled for the + device and the USB device directory will contain a file named + power/usb2_hardware_lpm. The file holds a string value (enable + or disable) indicating whether or not USB2 hardware LPM is + enabled for the device. Developer can write y/Y/1 or n/N/0 to + the file to enable/disable the feature. + +What: /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u1 + /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u2 +Date: November 2015 +Contact: Kevin Strasser <kevin.strasser@linux.intel.com> + Lu Baolu <baolu.lu@linux.intel.com> +Description: + If CONFIG_PM is set and a USB 3.0 lpm-capable device is plugged + in to a xHCI host which supports link PM, it will check if U1 + and U2 exit latencies have been set in the BOS descriptor; if + the check is passed and the host supports USB3 hardware LPM, + USB3 hardware LPM will be enabled for the device and the USB + device directory will contain two files named + power/usb3_hardware_lpm_u1 and power/usb3_hardware_lpm_u2. These + files hold a string value (enable or disable) indicating whether + or not USB3 hardware LPM U1 or U2 is enabled for the device. + +What: /sys/bus/usb/devices/.../removable +Date: February 2012 +Contact: Matthew Garrett <mjg@redhat.com> +Description: + Some information about whether a given USB device is + physically fixed to the platform can be inferred from a + combination of hub descriptor bits and platform-specific data + such as ACPI. This file will read either "removable" or + "fixed" if the information is available, and "unknown" + otherwise. + +What: /sys/bus/usb/devices/.../ltm_capable +Date: July 2012 +Contact: Sarah Sharp <sarah.a.sharp@linux.intel.com> +Description: + USB 3.0 devices may optionally support Latency Tolerance + Messaging (LTM). They indicate their support by setting a bit + in the bmAttributes field of their SuperSpeed BOS descriptors. + If that bit is set for the device, ltm_capable will read "yes". + If the device doesn't support LTM, the file will read "no". + The file will be present for all speeds of USB devices, and will + always read "no" for USB 1.1 and USB 2.0 devices. + +What: /sys/bus/usb/devices/.../(hub interface)/portX +Date: August 2012 +Contact: Lan Tianyu <tianyu.lan@intel.com> +Description: + The /sys/bus/usb/devices/.../(hub interface)/portX + is usb port device's sysfs directory. + +What: /sys/bus/usb/devices/.../(hub interface)/portX/connect_type +Date: January 2013 +Contact: Lan Tianyu <tianyu.lan@intel.com> +Description: + Some platforms provide usb port connect types through ACPI. + This attribute is to expose these information to user space. + The file will read "hotplug", "wired" and "not used" if the + information is available, and "unknown" otherwise. + +What: /sys/bus/usb/devices/.../(hub interface)/portX/quirks +Date: May 2018 +Contact: Nicolas Boichat <drinkcat@chromium.org> +Description: + In some cases, we care about time-to-active for devices + connected on a specific port (e.g. non-standard USB port like + pogo pins), where the device to be connected is known in + advance, and behaves well according to the specification. + This attribute is a bit-field that controls the behavior of + a specific port: + - Bit 0 of this field selects the "old" enumeration scheme, + as it is considerably faster (it only causes one USB reset + instead of 2). + The old enumeration scheme can also be selected globally + using /sys/module/usbcore/parameters/old_scheme_first, but + it is often not desirable as the new scheme was introduced to + increase compatibility with more devices. + - Bit 1 reduces TRSTRCY to the 10 ms that are required by the + USB 2.0 specification, instead of the 50 ms that are normally + used to help make enumeration work better on some high speed + devices. + +What: /sys/bus/usb/devices/.../(hub interface)/portX/over_current_count +Date: February 2018 +Contact: Richard Leitner <richard.leitner@skidata.com> +Description: + Most hubs are able to detect over-current situations on their + ports and report them to the kernel. This attribute is to expose + the number of over-current situation occurred on a specific port + to user space. This file will contain an unsigned 32 bit value + which wraps to 0 after its maximum is reached. + +What: /sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit +Date: November 2015 +Contact: Lu Baolu <baolu.lu@linux.intel.com> +Description: + Some USB3.0 devices are not friendly to USB3 LPM. usb3_lpm_permit + attribute allows enabling/disabling usb3 lpm of a port. It takes + effect both before and after a usb device is enumerated. Supported + values are "0" if both u1 and u2 are NOT permitted, "u1" if only u1 + is permitted, "u2" if only u2 is permitted, "u1_u2" if both u1 and + u2 are permitted. + +What: /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout +Date: May 2013 +Contact: Mathias Nyman <mathias.nyman@linux.intel.com> +Description: + USB 2.0 devices may support hardware link power management (LPM) + L1 sleep state. The usb2_lpm_l1_timeout attribute allows + tuning the timeout for L1 inactivity timer (LPM timer), e.g. + needed inactivity time before host requests the device to go to L1 sleep. + Useful for power management tuning. + Supported values are 0 - 65535 microseconds. + +What: /sys/bus/usb/devices/.../power/usb2_lpm_besl +Date: May 2013 +Contact: Mathias Nyman <mathias.nyman@linux.intel.com> +Description: + USB 2.0 devices that support hardware link power management (LPM) + L1 sleep state now use a best effort service latency value (BESL) to + indicate the best effort to resumption of service to the device after the + initiation of the resume event. + If the device does not have a preferred besl value then the host can select + one instead. This usb2_lpm_besl attribute allows to tune the host selected besl + value in order to tune power saving and service latency. + + Supported values are 0 - 15. + More information on how besl values map to microseconds can be found in + USB 2.0 ECN Errata for Link Power Management, section 4.10) + +What: /sys/bus/usb/devices/.../rx_lanes +Date: March 2018 +Contact: Mathias Nyman <mathias.nyman@linux.intel.com> +Description: + Number of rx lanes the device is using. + USB 3.2 adds Dual-lane support, 2 rx and 2 tx lanes over Type-C. + Inter-Chip SSIC devices support asymmetric lanes up to 4 lanes per + direction. Devices before USB 3.2 are single lane (rx_lanes = 1) + +What: /sys/bus/usb/devices/.../tx_lanes +Date: March 2018 +Contact: Mathias Nyman <mathias.nyman@linux.intel.com> +Description: + Number of tx lanes the device is using. + USB 3.2 adds Dual-lane support, 2 rx and 2 tx -lanes over Type-C. + Inter-Chip SSIC devices support asymmetric lanes up to 4 lanes per + direction. Devices before USB 3.2 are single lane (tx_lanes = 1) |