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platform/x86: Add driver to force WMI Thunderbolt controller power status

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Current implementations of Intel Thunderbolt controllers will go
into a low power mode when not in use.

Many machines containing these controllers also have a GPIO wired up
that can force the controller awake.  This is offered via a ACPI-WMI
interface intended to be manipulated by a userspace utility.

This mechanism is provided by Intel to OEMs to include in BIOS.
It uses an industry wide GUID that is populated in a separate _WDG
entry with no binary MOF.

This interface allows software such as fwupd to wake up thunderbolt
controllers to query the firmware version or flash new firmware.

Signed-off-by: Mario Limonciello <[email protected]>
Reviewed-by: Mika Westerberg <[email protected]>
Reviewed-by: Yehezkel Bernat <[email protected]>
Signed-off-by: Darren Hart (VMware) <[email protected]>
[andy fixed merge conflicts and bump kernel version for ABI]
Signed-off-by: Andy Shevchenko <[email protected]>
This commit is contained in:
Mario Limonciello 2017-09-08 10:23:11 -05:00 • committed by Andy Shevchenko
commit ce6a90027c
6 changed files with 146 additions and 0 deletions
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15
Documentation/admin-guide/thunderbolt.rst
View file

@ -197,3 +197,18 @@ information is missing.
To recover from this mode, one needs to flash a valid NVM image to the
host host controller in the same way it is done in the previous chapter.
Forcing power
-------------
Many OEMs include a method that can be used to force the power of a
thunderbolt controller to an "On" state even if nothing is connected.
If supported by your machine this will be exposed by the WMI bus with
a sysfs attribute called "force_power".
For example the intel-wmi-thunderbolt driver exposes this attribute in:
/sys/devices/platform/PNP0C14:00/wmi_bus/wmi_bus-PNP0C14:00/86CCFD48-205E-4A77-9C48-2021CBEDE341/force_power
To force the power to on, write 1 to this attribute file.
To disable force power, write 0 to this attribute file.
Note: it's currently not possible to query the force power state of a platform.