Hi all, In addition of tunneling PCIe, Display Port and USB traffic, Thunderbolt allows connecting two hosts (domains) over a Thunderbolt cable. It is possible to tunnel arbitrary data packets over such connection using high-speed DMA rings available in the Thunderbolt host controller.
In order to discover Thunderbolt services the other host supports, there is a software protocol running on top of the automatically configured control channel (ring 0). This protocol is called XDomain discovery protocol and it uses XDomain properties to describe the host (domain) and the services it supports. Once both sides have agreed what services are supported they can enable high-speed DMA rings to transfer data over the cable. This series adds support for the XDomain protocol so that we expose each remote connection as Thunderbolt XDomain device and each service as Thunderbolt service device. On top of that we create an API that allows writing drivers for these services and finally we provide an example Thunderbolt service driver that creates virtual ethernet inferface that allows tunneling networking packets over Thunderbolt cable. The API could be used for creating other Thunderbolt services, such as tunneling SCSI for example. The XDomain protocol and networking support is also available in macOS and Windows so this makes it possible to connect Linux to macOS and Windows as well. The patches are based on previous Thunderbolt networking patch series by Amir Levy and Michael Jamet, that can be found here: https://lwn.net/Articles/705998/ The main difference to that patch series is that we have the XDomain protocol running in the kernel now so there is no need for a separate userspace daemon. Note this does not affect the existing functionality, so security levels and NVM firmware upgrade continue to work as before (with the small exception that now sysfs also shows the XDomain connections and services in addition to normal Thunderbolt devices). It is also possible to connect up to 5 Thunderbolt devices and then another host, and the network driver works exactly the same. This is second version of the patch series. The previous version (v1) can be found here: https://lwn.net/Articles/734019/ Changes from the v1: * Add include/linux/thunderbolt.h to MAINTAINERS * Correct Linux version and date of new sysfs entries in Documentation/ABI/testing/sysfs-bus-thunderbolt * Move network driver from drivers/thunderbolt/net.c to drivers/net/thunderbolt.c and update it to follow coding style in drivers/net/*. * Add MAINTAINERS entry for the network driver * Minor cleanups In case someone wants to try this out, patch [16/16] adds documentation how the networking driver can be used. In short, if you connect Linux to a macOS or Windows, everything is done automatically (as those systems have the networking service enabled by default). For Linux to Linux connection one host needs to load the networking driver first (so that the other side can locate the networking service and load the corresponding driver). Amir Levy (1): net: Add support for networking over Thunderbolt cable Mika Westerberg (15): byteorder: Move {cpu_to_be32,be32_to_cpu}_array() from Thunderbolt to core thunderbolt: Add support for XDomain properties thunderbolt: Move enum tb_cfg_pkg_type to thunderbolt.h thunderbolt: Move thunderbolt domain structure to thunderbolt.h thunderbolt: Move tb_switch_phy_port_from_link() to thunderbolt.h thunderbolt: Add support for XDomain discovery protocol thunderbolt: Configure interrupt throttling for all interrupts thunderbolt: Add support for frame mode thunderbolt: Export ring handling functions to modules thunderbolt: Move ring descriptor flags to thunderbolt.h thunderbolt: Use spinlock in ring serialization thunderbolt: Use spinlock in NHI serialization thunderbolt: Add polling mode for rings thunderbolt: Add function to retrieve DMA device for the ring thunderbolt: Allocate ring HopID automatically if requested Documentation/ABI/testing/sysfs-bus-thunderbolt | 48 + Documentation/admin-guide/thunderbolt.rst | 24 + MAINTAINERS | 7 + drivers/net/Kconfig | 12 + drivers/net/Makefile | 3 + drivers/net/thunderbolt.c | 1379 ++++++++++++++++++++ drivers/thunderbolt/Makefile | 2 +- drivers/thunderbolt/ctl.c | 46 +- drivers/thunderbolt/ctl.h | 3 +- drivers/thunderbolt/domain.c | 197 ++- drivers/thunderbolt/icm.c | 218 +++- drivers/thunderbolt/nhi.c | 409 ++++-- drivers/thunderbolt/nhi.h | 141 +- drivers/thunderbolt/nhi_regs.h | 11 +- drivers/thunderbolt/property.c | 670 ++++++++++ drivers/thunderbolt/switch.c | 7 +- drivers/thunderbolt/tb.h | 88 +- drivers/thunderbolt/tb_msgs.h | 140 +- drivers/thunderbolt/xdomain.c | 1576 +++++++++++++++++++++++ include/linux/byteorder/generic.h | 16 + include/linux/mod_devicetable.h | 26 + include/linux/thunderbolt.h | 598 +++++++++ scripts/mod/devicetable-offsets.c | 7 + scripts/mod/file2alias.c | 25 + 24 files changed, 5304 insertions(+), 349 deletions(-) create mode 100644 drivers/net/thunderbolt.c create mode 100644 drivers/thunderbolt/property.c create mode 100644 drivers/thunderbolt/xdomain.c create mode 100644 include/linux/thunderbolt.h -- 2.14.1
