ca9c9d0c92
This patch adds two sysfs files for each usb hub port to allow userspace to control the port power policy. For an upcoming Intel xHCI roothub, this will translate into ACPI calls to completely power off or power on the port. As a reminder, when these ports are completely powered off, the USB host and device will see a physical disconnect. All future USB device connections will be lost, and the device will not be able to signal a remote wakeup. The control sysfs file can be written to with two options: "on" - port power must be on. "off" - port must be off. The state sysfs file reports usb port's power state: "on" - powered on "off" - powered off "error" - can't get power state For now, let userspace dictate the port power off policy. Future patches may add an in-kernel policy. Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Lan Tianyu <tianyu.lan@intel.com> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
254 lines
9.1 KiB
Plaintext
254 lines
9.1 KiB
Plaintext
What: /sys/bus/usb/devices/.../power/autosuspend
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Date: March 2007
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KernelVersion: 2.6.21
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Contact: Alan Stern <stern@rowland.harvard.edu>
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Description:
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Each USB device directory will contain a file named
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power/autosuspend. This file holds the time (in seconds)
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the device must be idle before it will be autosuspended.
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0 means the device will be autosuspended as soon as
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possible. Negative values will prevent the device from
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being autosuspended at all, and writing a negative value
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will resume the device if it is already suspended.
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The autosuspend delay for newly-created devices is set to
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the value of the usbcore.autosuspend module parameter.
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What: /sys/bus/usb/devices/.../power/persist
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Date: May 2007
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KernelVersion: 2.6.23
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Contact: Alan Stern <stern@rowland.harvard.edu>
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Description:
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If CONFIG_USB_PERSIST is set, then each USB device directory
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will contain a file named power/persist. The file holds a
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boolean value (0 or 1) indicating whether or not the
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"USB-Persist" facility is enabled for the device. Since the
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facility is inherently dangerous, it is disabled by default
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for all devices except hubs. For more information, see
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Documentation/usb/persist.txt.
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What: /sys/bus/usb/device/.../power/connected_duration
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Date: January 2008
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KernelVersion: 2.6.25
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Contact: Sarah Sharp <sarah.a.sharp@intel.com>
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Description:
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If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file
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is present. When read, it returns the total time (in msec)
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that the USB device has been connected to the machine. This
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file is read-only.
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Users:
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PowerTOP <power@bughost.org>
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http://www.lesswatts.org/projects/powertop/
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What: /sys/bus/usb/device/.../power/active_duration
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Date: January 2008
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KernelVersion: 2.6.25
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Contact: Sarah Sharp <sarah.a.sharp@intel.com>
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Description:
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If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file
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is present. When read, it returns the total time (in msec)
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that the USB device has been active, i.e. not in a suspended
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state. This file is read-only.
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Tools can use this file and the connected_duration file to
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compute the percentage of time that a device has been active.
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For example,
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echo $((100 * `cat active_duration` / `cat connected_duration`))
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will give an integer percentage. Note that this does not
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account for counter wrap.
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Users:
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PowerTOP <power@bughost.org>
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http://www.lesswatts.org/projects/powertop/
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What: /sys/bus/usb/device/<busnum>-<devnum>...:<config num>-<interface num>/supports_autosuspend
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Date: January 2008
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KernelVersion: 2.6.27
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Contact: Sarah Sharp <sarah.a.sharp@intel.com>
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Description:
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When read, this file returns 1 if the interface driver
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for this interface supports autosuspend. It also
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returns 1 if no driver has claimed this interface, as an
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unclaimed interface will not stop the device from being
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autosuspended if all other interface drivers are idle.
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The file returns 0 if autosuspend support has not been
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added to the driver.
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Users:
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USB PM tool
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git://git.moblin.org/users/sarah/usb-pm-tool/
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What: /sys/bus/usb/device/.../authorized
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Date: July 2008
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KernelVersion: 2.6.26
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Contact: David Vrabel <david.vrabel@csr.com>
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Description:
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Authorized devices are available for use by device
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drivers, non-authorized one are not. By default, wired
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USB devices are authorized.
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Certified Wireless USB devices are not authorized
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initially and should be (by writing 1) after the
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device has been authenticated.
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What: /sys/bus/usb/device/.../wusb_cdid
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Date: July 2008
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KernelVersion: 2.6.27
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Contact: David Vrabel <david.vrabel@csr.com>
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Description:
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For Certified Wireless USB devices only.
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A devices's CDID, as 16 space-separated hex octets.
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What: /sys/bus/usb/device/.../wusb_ck
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Date: July 2008
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KernelVersion: 2.6.27
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Contact: David Vrabel <david.vrabel@csr.com>
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Description:
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For Certified Wireless USB devices only.
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Write the device's connection key (CK) to start the
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authentication of the device. The CK is 16
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space-separated hex octets.
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What: /sys/bus/usb/device/.../wusb_disconnect
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Date: July 2008
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KernelVersion: 2.6.27
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Contact: David Vrabel <david.vrabel@csr.com>
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Description:
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For Certified Wireless USB devices only.
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Write a 1 to force the device to disconnect
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(equivalent to unplugging a wired USB device).
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What: /sys/bus/usb/drivers/.../new_id
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Date: October 2011
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Contact: linux-usb@vger.kernel.org
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Description:
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Writing a device ID to this file will attempt to
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dynamically add a new device ID to a USB device driver.
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This may allow the driver to support more hardware than
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was included in the driver's static device ID support
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table at compile time. The format for the device ID is:
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idVendor idProduct bInterfaceClass.
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The vendor ID and device ID fields are required, the
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interface class is optional.
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Upon successfully adding an ID, the driver will probe
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for the device and attempt to bind to it. For example:
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# echo "8086 10f5" > /sys/bus/usb/drivers/foo/new_id
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Reading from this file will list all dynamically added
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device IDs in the same format, with one entry per
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line. For example:
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# cat /sys/bus/usb/drivers/foo/new_id
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8086 10f5
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dead beef 06
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f00d cafe
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The list will be truncated at PAGE_SIZE bytes due to
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sysfs restrictions.
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What: /sys/bus/usb-serial/drivers/.../new_id
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Date: October 2011
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Contact: linux-usb@vger.kernel.org
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Description:
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For serial USB drivers, this attribute appears under the
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extra bus folder "usb-serial" in sysfs; apart from that
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difference, all descriptions from the entry
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"/sys/bus/usb/drivers/.../new_id" apply.
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What: /sys/bus/usb/drivers/.../remove_id
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Date: November 2009
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Contact: CHENG Renquan <rqcheng@smu.edu.sg>
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Description:
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Writing a device ID to this file will remove an ID
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that was dynamically added via the new_id sysfs entry.
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The format for the device ID is:
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idVendor idProduct. After successfully
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removing an ID, the driver will no longer support the
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device. This is useful to ensure auto probing won't
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match the driver to the device. For example:
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# echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id
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Reading from this file will list the dynamically added
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device IDs, exactly like reading from the entry
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"/sys/bus/usb/drivers/.../new_id"
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What: /sys/bus/usb/device/.../avoid_reset_quirk
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Date: December 2009
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Contact: Oliver Neukum <oliver@neukum.org>
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Description:
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Writing 1 to this file tells the kernel that this
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device will morph into another mode when it is reset.
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Drivers will not use reset for error handling for
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such devices.
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Users:
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usb_modeswitch
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What: /sys/bus/usb/devices/.../power/usb2_hardware_lpm
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Date: September 2011
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Contact: Andiry Xu <andiry.xu@amd.com>
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Description:
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If CONFIG_USB_SUSPEND is set and a USB 2.0 lpm-capable device
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is plugged in to a xHCI host which support link PM, it will
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perform a LPM test; if the test is passed and host supports
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USB2 hardware LPM (xHCI 1.0 feature), USB2 hardware LPM will
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be enabled for the device and the USB device directory will
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contain a file named power/usb2_hardware_lpm. The file holds
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a string value (enable or disable) indicating whether or not
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USB2 hardware LPM is enabled for the device. Developer can
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write y/Y/1 or n/N/0 to the file to enable/disable the
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feature.
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What: /sys/bus/usb/devices/.../removable
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Date: February 2012
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Contact: Matthew Garrett <mjg@redhat.com>
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Description:
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Some information about whether a given USB device is
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physically fixed to the platform can be inferred from a
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combination of hub descriptor bits and platform-specific data
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such as ACPI. This file will read either "removable" or
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"fixed" if the information is available, and "unknown"
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otherwise.
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What: /sys/bus/usb/devices/.../ltm_capable
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Date: July 2012
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Contact: Sarah Sharp <sarah.a.sharp@linux.intel.com>
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Description:
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USB 3.0 devices may optionally support Latency Tolerance
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Messaging (LTM). They indicate their support by setting a bit
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in the bmAttributes field of their SuperSpeed BOS descriptors.
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If that bit is set for the device, ltm_capable will read "yes".
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If the device doesn't support LTM, the file will read "no".
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The file will be present for all speeds of USB devices, and will
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always read "no" for USB 1.1 and USB 2.0 devices.
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What: /sys/bus/usb/devices/.../(hub interface)/portX
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Date: August 2012
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Contact: Lan Tianyu <tianyu.lan@intel.com>
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Description:
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The /sys/bus/usb/devices/.../(hub interface)/portX
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is usb port device's sysfs directory.
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What: /sys/bus/usb/devices/.../(hub interface)/portX/control
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Date: August 2012
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Contact: Lan Tianyu <tianyu.lan@intel.com>
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Description:
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The /sys/bus/usb/devices/.../(hub interface)/portX/control
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attribute allows user space to control the power policy on
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the usb port.
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All ports have one of the following two values for control
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"on" - port power must be on.
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"off" - port power must be off.
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What: /sys/bus/usb/devices/.../(hub interface)/portX/state
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Date: August 2012
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Contact: Lan Tianyu <tianyu.lan@intel.com>
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Description:
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The /sys/bus/usb/devices/.../(hub interface)/portX/state
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attribute allows user space to check hub port's power state.
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All ports have three following states
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"on" - port power on
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"off" - port power off
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"error" - can't get the hub port's power state
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