linux/Documentation/admin-guide/thunderbolt.rst
Linus Torvalds 07c455ee22 platform-drivers-x86 for v4.15-1
For this cycle we have quite an update for the Dell SMBIOS driver
 including WMI work to provide an interface for SMBIOS tokens via sysfs
 and WMI support for 2017+ Dell laptop models. SMM dispatcher code is
 split into a separate driver followed by a new WMI dispatcher.
 The latter provides a character device interface to user space.
 
 The pull request contains a merge of immutable branch from Wolfram Sang
 in order to apply a dependent fix to the Intel CherryTrail Battery
 Management driver.
 
 Other Intel drivers got a lot of cleanups. The Turbo Boost Max 3.0
 support is added for Intel Skylake.
 
 Peaq WMI hotkeys driver gets its own maintainer and white list of
 supported models.
 
 Silead DMI is expanded to support few additional platforms.
 
 Tablet mode via GMMS ACPI method is added to support some ThinkPad
 tablets.
 
 Two commits appear here which were previously merged during the
 v4.14-rcX cycle:
 
 - d7ca5ebf24 platform/x86: intel_pmc_ipc: Use devm_* calls in driver probe function
 - e3075fd6f8 platform/x86: intel_pmc_ipc: Use spin_lock to protect GCR updates
 
 Add driver to force WMI Thunderbolt controller power status:
  - Add driver to force WMI Thunderbolt controller power status
 
 asus-wmi:
  -  Add lightbar led support
 
 dell-laptop:
  -  Allocate buffer before rfkill use
 
 dell-smbios:
  -  fix string overflow
  -  Add filtering support
  -  Introduce dispatcher for SMM calls
  -  Add a sysfs interface for SMBIOS tokens
  -  only run if proper oem string is detected
  -  Prefix class/select with cmd_
  -  Add pr_fmt definition to driver
 
 dell-smbios-smm:
  -  test for WSMT
 
 dell-smbios-wmi:
  -  release mutex lock on WMI call failure
  -  introduce userspace interface
  -  Add new WMI dispatcher driver
 
 dell-smo8800:
  -  remove redundant assignments to byte_data
 
 dell-wmi:
  -  don't check length returned
  -  clean up wmi descriptor check
  -  increase severity of some failures
  -  Do not match on descriptor GUID modalias
  -  Label driver as handling notifications
 
 dell-*wmi*:
  -  Relay failed initial probe to dependent drivers
 
 dell-wmi-descriptor:
  -  check if memory was allocated
  -  split WMI descriptor into it's own driver
 
 fujitsu-laptop:
  -  Fix radio LED detection
  -  Don't oops when FUJ02E3 is not presnt
 
 hp_accel:
  -  Add quirk for HP ProBook 440 G4
 
 hp-wmi:
  -  Fix tablet mode detection for convertibles
 
 ideapad-laptop:
  -  Add Lenovo Yoga 920-13IKB to no_hw_rfkill dmi list
 
 intel_cht_int33fe:
  -  Update fusb302 type string, add properties
  -  make a couple of local functions static
  -  Work around BIOS bug on some devices
 
 intel-hid:
  -  Power button suspend on Dell Latitude 7275
 
 intel_ips:
  -  Convert timers to use timer_setup()
  -  Remove FSF address from GPL notice
  -  Remove unneeded fields and label
  -  Keep pointer to struct device
  -  Use PCI_VDEVICE() macro
  -  Switch to new PCI IRQ allocation API
  -  Simplify error handling via devres API
 
 intel_pmc_ipc:
  -  Revert Use MFD framework to create dependent devices
  -  Use MFD framework to create dependent devices
  -  Use spin_lock to protect GCR updates
  -  Use devm_* calls in driver probe function
 
 intel_punit_ipc:
  -  Fix resource ioremap warning
 
 intel_telemetry:
  -  Remove useless default in Kconfig
  -  Add needed inclusion
  -  cleanup redundant headers
  -  Fix typos
  -  Fix load failure info
 
 intel_telemetry_debugfs:
  -  Use standard ARRAY_SIZE() macro
 
 intel_turbo_max_3:
  -  Add Skylake platform
 
 intel-wmi-thunderbolt:
  -  Silence error cases
 
 MAINTAINERS:
  -  Add entry for the PEAQ WMI hotkeys driver
 
 mlx-platform:
  -  make a couple of structures static
 
 peaq_wmi:
  -  Fix missing terminating entry for peaq_dmi_table
 
 peaq-wmi:
  -  Remove unnecessary checks from peaq_wmi_exit
  -  Add DMI check before binding to the WMI interface
  -  Revert Blacklist Lenovo ideapad 700-15ISK
  -  Blacklist Lenovo ideapad 700-15ISK
 
 silead_dmi:
  -  Add silead, home-button property to some tablets
  -  Add entry for the Digma e200 tablet
  -  Fix GP-electronic T701 entry
  -  Add entry for the Chuwi Hi8 Pro tablet
 
 sony-laptop:
  -  Drop variable assignment in sony_nc_setup_rfkill()
  -  Fix error handling in sony_nc_setup_rfkill()
 
 thinkpad_acpi:
  -  Implement tablet mode using GMMS method
 
 tools/wmi:
  -  add a sample for dell smbios communication over WMI
 
 wmi:
  -  release mutex on module acquistion failure
  -  create userspace interface for drivers
  -  Don't allow drivers to get each other's GUIDs
  -  Add new method wmidev_evaluate_method
  -  Destroy on cleanup rather than unregister
  -  Cleanup exit routine in reverse order of init
  -  Sort include list
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Merge tag 'platform-drivers-x86-v4.15-1' of git://git.infradead.org/linux-platform-drivers-x86

Pull x86 platform driver updates from Andy Shevchenko:
 "Here is the collected material against Platform Drivers x86 subsystem.
  It's rather bit busy cycle for PDx86, mostly due to Dell SMBIOS driver
  activity

  For this cycle we have quite an update for the Dell SMBIOS driver
  including WMI work to provide an interface for SMBIOS tokens via sysfs
  and WMI support for 2017+ Dell laptop models. SMM dispatcher code is
  split into a separate driver followed by a new WMI dispatcher. The
  latter provides a character device interface to user space.

  The git history also contains a merge of immutable branch from Wolfram
  Sang in order to apply a dependent fix to the Intel CherryTrail
  Battery Management driver.

  Other Intel drivers got a lot of cleanups. The Turbo Boost Max 3.0
  support is added for Intel Skylake.

  Peaq WMI hotkeys driver gets its own maintainer and white list of
  supported models.

  Silead DMI is expanded to support few additional platforms.

  Tablet mode via GMMS ACPI method is added to support some ThinkPad
  tablets.

  new driver:
   - Add driver to force WMI Thunderbolt controller power status

  asus-wmi:
   -  Add lightbar led support

  dell-laptop:
   -  Allocate buffer before rfkill use

  dell-smbios:
   -  fix string overflow
   -  Add filtering support
   -  Introduce dispatcher for SMM calls
   -  Add a sysfs interface for SMBIOS tokens
   -  only run if proper oem string is detected
   -  Prefix class/select with cmd_
   -  Add pr_fmt definition to driver

  dell-smbios-smm:
   -  test for WSMT

  dell-smbios-wmi:
   -  release mutex lock on WMI call failure
   -  introduce userspace interface
   -  Add new WMI dispatcher driver

  dell-smo8800:
   -  remove redundant assignments to byte_data

  dell-wmi:
   -  don't check length returned
   -  clean up wmi descriptor check
   -  increase severity of some failures
   -  Do not match on descriptor GUID modalias
   -  Label driver as handling notifications

  dell-*wmi*:
   -  Relay failed initial probe to dependent drivers

  dell-wmi-descriptor:
   -  check if memory was allocated
   -  split WMI descriptor into it's own driver

  fujitsu-laptop:
   -  Fix radio LED detection
   -  Don't oops when FUJ02E3 is not presnt

  hp_accel:
   -  Add quirk for HP ProBook 440 G4

  hp-wmi:
   -  Fix tablet mode detection for convertibles

  ideapad-laptop:
   -  Add Lenovo Yoga 920-13IKB to no_hw_rfkill dmi list

  intel_cht_int33fe:
   -  Update fusb302 type string, add properties
   -  make a couple of local functions static
   -  Work around BIOS bug on some devices

  intel-hid:
   -  Power button suspend on Dell Latitude 7275

  intel_ips:
   -  Convert timers to use timer_setup()
   -  Remove FSF address from GPL notice
   -  Remove unneeded fields and label
   -  Keep pointer to struct device
   -  Use PCI_VDEVICE() macro
   -  Switch to new PCI IRQ allocation API
   -  Simplify error handling via devres API

  intel_pmc_ipc:
   -  Revert Use MFD framework to create dependent devices
   -  Use MFD framework to create dependent devices
   -  Use spin_lock to protect GCR updates
   -  Use devm_* calls in driver probe function

  intel_punit_ipc:
   -  Fix resource ioremap warning

  intel_telemetry:
   -  Remove useless default in Kconfig
   -  Add needed inclusion
   -  cleanup redundant headers
   -  Fix typos
   -  Fix load failure info

  intel_telemetry_debugfs:
   -  Use standard ARRAY_SIZE() macro

  intel_turbo_max_3:
   -  Add Skylake platform

  intel-wmi-thunderbolt:
   -  Silence error cases

  mlx-platform:
   -  make a couple of structures static

  peaq_wmi:
   -  Fix missing terminating entry for peaq_dmi_table

  peaq-wmi:
   -  Remove unnecessary checks from peaq_wmi_exit
   -  Add DMI check before binding to the WMI interface
   -  Revert Blacklist Lenovo ideapad 700-15ISK
   -  Blacklist Lenovo ideapad 700-15ISK

  silead_dmi:
   -  Add silead, home-button property to some tablets
   -  Add entry for the Digma e200 tablet
   -  Fix GP-electronic T701 entry
   -  Add entry for the Chuwi Hi8 Pro tablet

  sony-laptop:
   -  Drop variable assignment in sony_nc_setup_rfkill()
   -  Fix error handling in sony_nc_setup_rfkill()

  thinkpad_acpi:
   -  Implement tablet mode using GMMS method

  tools/wmi:
   -  add a sample for dell smbios communication over WMI

  wmi:
   -  release mutex on module acquistion failure
   -  create userspace interface for drivers
   -  Don't allow drivers to get each other's GUIDs
   -  Add new method wmidev_evaluate_method
   -  Destroy on cleanup rather than unregister
   -  Cleanup exit routine in reverse order of init
   -  Sort include list"

* tag 'platform-drivers-x86-v4.15-1' of git://git.infradead.org/linux-platform-drivers-x86: (74 commits)
  platform/x86: silead_dmi: Add silead, home-button property to some tablets
  platform/x86: dell-laptop: Allocate buffer before rfkill use
  platform/x86: dell-*wmi*: Relay failed initial probe to dependent drivers
  platform/x86: dell-wmi-descriptor: check if memory was allocated
  platform/x86: Revert intel_pmc_ipc: Use MFD framework to create dependent devices
  platform/x86: dell-smbios-wmi: release mutex lock on WMI call failure
  platform/x86: wmi: release mutex on module acquistion failure
  platform/x86: dell-smbios: fix string overflow
  platform/x86: intel_pmc_ipc: Use MFD framework to create dependent devices
  platform/x86: intel_punit_ipc: Fix resource ioremap warning
  platform/x86: dell-smo8800: remove redundant assignments to byte_data
  platform/x86: hp-wmi: Fix tablet mode detection for convertibles
  platform/x86: intel_ips: Convert timers to use timer_setup()
  platform/x86: sony-laptop: Drop variable assignment in sony_nc_setup_rfkill()
  platform/x86: sony-laptop: Fix error handling in sony_nc_setup_rfkill()
  tools/wmi: add a sample for dell smbios communication over WMI
  platform/x86: dell-smbios-wmi: introduce userspace interface
  platform/x86: wmi: create userspace interface for drivers
  platform/x86: dell-smbios: Add filtering support
  platform/x86: dell-smbios-smm: test for WSMT
  ...
2017-11-18 10:26:57 -08:00

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ReStructuredText

=============
Thunderbolt
=============
The interface presented here is not meant for end users. Instead there
should be a userspace tool that handles all the low-level details, keeps
database of the authorized devices and prompts user for new connections.
More details about the sysfs interface for Thunderbolt devices can be
found in ``Documentation/ABI/testing/sysfs-bus-thunderbolt``.
Those users who just want to connect any device without any sort of
manual work, can add following line to
``/etc/udev/rules.d/99-local.rules``::
ACTION=="add", SUBSYSTEM=="thunderbolt", ATTR{authorized}=="0", ATTR{authorized}="1"
This will authorize all devices automatically when they appear. However,
keep in mind that this bypasses the security levels and makes the system
vulnerable to DMA attacks.
Security levels and how to use them
-----------------------------------
Starting from Intel Falcon Ridge Thunderbolt controller there are 4
security levels available. The reason for these is the fact that the
connected devices can be DMA masters and thus read contents of the host
memory without CPU and OS knowing about it. There are ways to prevent
this by setting up an IOMMU but it is not always available for various
reasons.
The security levels are as follows:
none
All devices are automatically connected by the firmware. No user
approval is needed. In BIOS settings this is typically called
*Legacy mode*.
user
User is asked whether the device is allowed to be connected.
Based on the device identification information available through
``/sys/bus/thunderbolt/devices``. user then can do the decision.
In BIOS settings this is typically called *Unique ID*.
secure
User is asked whether the device is allowed to be connected. In
addition to UUID the device (if it supports secure connect) is sent
a challenge that should match the expected one based on a random key
written to ``key`` sysfs attribute. In BIOS settings this is
typically called *One time saved key*.
dponly
The firmware automatically creates tunnels for Display Port and
USB. No PCIe tunneling is done. In BIOS settings this is
typically called *Display Port Only*.
The current security level can be read from
``/sys/bus/thunderbolt/devices/domainX/security`` where ``domainX`` is
the Thunderbolt domain the host controller manages. There is typically
one domain per Thunderbolt host controller.
If the security level reads as ``user`` or ``secure`` the connected
device must be authorized by the user before PCIe tunnels are created
(e.g the PCIe device appears).
Each Thunderbolt device plugged in will appear in sysfs under
``/sys/bus/thunderbolt/devices``. The device directory carries
information that can be used to identify the particular device,
including its name and UUID.
Authorizing devices when security level is ``user`` or ``secure``
-----------------------------------------------------------------
When a device is plugged in it will appear in sysfs as follows::
/sys/bus/thunderbolt/devices/0-1/authorized - 0
/sys/bus/thunderbolt/devices/0-1/device - 0x8004
/sys/bus/thunderbolt/devices/0-1/device_name - Thunderbolt to FireWire Adapter
/sys/bus/thunderbolt/devices/0-1/vendor - 0x1
/sys/bus/thunderbolt/devices/0-1/vendor_name - Apple, Inc.
/sys/bus/thunderbolt/devices/0-1/unique_id - e0376f00-0300-0100-ffff-ffffffffffff
The ``authorized`` attribute reads 0 which means no PCIe tunnels are
created yet. The user can authorize the device by simply::
# echo 1 > /sys/bus/thunderbolt/devices/0-1/authorized
This will create the PCIe tunnels and the device is now connected.
If the device supports secure connect, and the domain security level is
set to ``secure``, it has an additional attribute ``key`` which can hold
a random 32 byte value used for authorization and challenging the device in
future connects::
/sys/bus/thunderbolt/devices/0-3/authorized - 0
/sys/bus/thunderbolt/devices/0-3/device - 0x305
/sys/bus/thunderbolt/devices/0-3/device_name - AKiTiO Thunder3 PCIe Box
/sys/bus/thunderbolt/devices/0-3/key -
/sys/bus/thunderbolt/devices/0-3/vendor - 0x41
/sys/bus/thunderbolt/devices/0-3/vendor_name - inXtron
/sys/bus/thunderbolt/devices/0-3/unique_id - dc010000-0000-8508-a22d-32ca6421cb16
Notice the key is empty by default.
If the user does not want to use secure connect it can just ``echo 1``
to the ``authorized`` attribute and the PCIe tunnels will be created in
the same way than in ``user`` security level.
If the user wants to use secure connect, the first time the device is
plugged a key needs to be created and send to the device::
# key=$(openssl rand -hex 32)
# echo $key > /sys/bus/thunderbolt/devices/0-3/key
# echo 1 > /sys/bus/thunderbolt/devices/0-3/authorized
Now the device is connected (PCIe tunnels are created) and in addition
the key is stored on the device NVM.
Next time the device is plugged in the user can verify (challenge) the
device using the same key::
# echo $key > /sys/bus/thunderbolt/devices/0-3/key
# echo 2 > /sys/bus/thunderbolt/devices/0-3/authorized
If the challenge the device returns back matches the one we expect based
on the key, the device is connected and the PCIe tunnels are created.
However, if the challenge failed no tunnels are created and error is
returned to the user.
If the user still wants to connect the device it can either approve
the device without a key or write new key and write 1 to the
``authorized`` file to get the new key stored on the device NVM.
Upgrading NVM on Thunderbolt device or host
-------------------------------------------
Since most of the functionality is handled in a firmware running on a
host controller or a device, it is important that the firmware can be
upgraded to the latest where possible bugs in it have been fixed.
Typically OEMs provide this firmware from their support site.
There is also a central site which has links where to download firmwares
for some machines:
`Thunderbolt Updates <https://thunderbolttechnology.net/updates>`_
Before you upgrade firmware on a device or host, please make sure it is
the suitable. Failing to do that may render the device (or host) in a
state where it cannot be used properly anymore without special tools!
Host NVM upgrade on Apple Macs is not supported.
Once the NVM image has been downloaded, you need to plug in a
Thunderbolt device so that the host controller appears. It does not
matter which device is connected (unless you are upgrading NVM on a
device - then you need to connect that particular device).
Note OEM-specific method to power the controller up ("force power") may
be available for your system in which case there is no need to plug in a
Thunderbolt device.
After that we can write the firmware to the non-active parts of the NVM
of the host or device. As an example here is how Intel NUC6i7KYK (Skull
Canyon) Thunderbolt controller NVM is upgraded::
# dd if=KYK_TBT_FW_0018.bin of=/sys/bus/thunderbolt/devices/0-0/nvm_non_active0/nvmem
Once the operation completes we can trigger NVM authentication and
upgrade process as follows::
# echo 1 > /sys/bus/thunderbolt/devices/0-0/nvm_authenticate
If no errors are returned, the host controller shortly disappears. Once
it comes back the driver notices it and initiates a full power cycle.
After a while the host controller appears again and this time it should
be fully functional.
We can verify that the new NVM firmware is active by running following
commands::
# cat /sys/bus/thunderbolt/devices/0-0/nvm_authenticate
0x0
# cat /sys/bus/thunderbolt/devices/0-0/nvm_version
18.0
If ``nvm_authenticate`` contains anything else than 0x0 it is the error
code from the last authentication cycle, which means the authentication
of the NVM image failed.
Note names of the NVMem devices ``nvm_activeN`` and ``nvm_non_activeN``
depends on the order they are registered in the NVMem subsystem. N in
the name is the identifier added by the NVMem subsystem.
Upgrading NVM when host controller is in safe mode
--------------------------------------------------
If the existing NVM is not properly authenticated (or is missing) the
host controller goes into safe mode which means that only available
functionality is flashing new NVM image. When in this mode the reading
``nvm_version`` fails with ``ENODATA`` and the device identification
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.
Networking over Thunderbolt cable
---------------------------------
Thunderbolt technology allows software communication across two hosts
connected by a Thunderbolt cable.
It is possible to tunnel any kind of traffic over Thunderbolt link but
currently we only support Apple ThunderboltIP protocol.
If the other host is running Windows or macOS only thing you need to
do is to connect Thunderbolt cable between the two hosts, the
``thunderbolt-net`` is loaded automatically. If the other host is also
Linux you should load ``thunderbolt-net`` manually on one host (it does
not matter which one)::
# modprobe thunderbolt-net
This triggers module load on the other host automatically. If the driver
is built-in to the kernel image, there is no need to do anything.
The driver will create one virtual ethernet interface per Thunderbolt
port which are named like ``thunderbolt0`` and so on. From this point
you can either use standard userspace tools like ``ifconfig`` to
configure the interface or let your GUI to handle it automatically.
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.