net: Add support for networking over Thunderbolt cable

ThunderboltIP is a protocol created by Apple to tunnel IP/ethernet
traffic over a Thunderbolt cable. The protocol consists of configuration
phase where each side sends ThunderboltIP login packets (the protocol is
determined by UUID in the XDomain packet header) over the configuration
channel. Once both sides get positive acknowledgment to their login
packet, they configure high-speed DMA path accordingly. This DMA path is
then used to transmit and receive networking traffic.

This patch creates a virtual ethernet interface the host software can
use in the same way as any other networking interface. Once the
interface is brought up successfully network packets get tunneled over
the Thunderbolt cable to the remote host and back.

The connection is terminated by sending a ThunderboltIP logout packet
over the configuration channel. We do this when the network interface is
brought down by user or the driver is unloaded.

Signed-off-by: Amir Levy <amir.jer.levy@intel.com>
Signed-off-by: Michael Jamet <michael.jamet@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/admin-guide/thunderbolt.rst

@@ -197,3 +197,27 @@ 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.

drivers/net/Kconfig

@@ -483,6 +483,18 @@ config FUJITSU_ES
 	  This driver provides support for Extended Socket network device
           on Extended Partitioning of FUJITSU PRIMEQUEST 2000 E2 series.
 
+config THUNDERBOLT_NET
+	tristate "Networking over Thunderbolt cable"
+	depends on THUNDERBOLT && INET
+	help
+	  Select this if you want to create network between two
+	  computers over a Thunderbolt cable. The driver supports Apple
+	  ThunderboltIP protocol and allows communication with any host
+	  supporting the same protocol including Windows and macOS.
+
+	  To compile this driver a module, choose M here. The module will be
+	  called thunderbolt-net.
+
 source "drivers/net/hyperv/Kconfig"
 
 endif # NETDEVICES

drivers/net/Makefile

@@ -74,3 +74,6 @@ obj-$(CONFIG_HYPERV_NET) += hyperv/
 obj-$(CONFIG_NTB_NETDEV) += ntb_netdev.o
 
 obj-$(CONFIG_FUJITSU_ES) += fjes/
+
+thunderbolt-net-y += thunderbolt.o
+obj-$(CONFIG_THUNDERBOLT_NET) += thunderbolt-net.o