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Mika Westerberg
6db21d817b
Introduce USB4STREAM protocol and Linux implementation. This allows two
(or more) hosts to transfer data directly over Thunderbolt/USB4 cable
through a character device without need to go through the network stack.
Any application that supports read(2) and write(2) in some form should
be able to use the device without changes. The data is sent out to the
other side over a tunnel inside Thunderbolt/USB4 fabric. The character
device is called /dev/tbstreamX where X is the minor number starting
from 0.
All stream devices need to be configured first. This is done through
ConfigFS interface. There can be multiple streams at the same time (this
depends on number of DMA rings and available HopIDs) and a single stream
supports traffic in both directions. For example there could be an
application that uses one stream as control channel and another one as
bi-directional data channel.
A real use-case for this is to take a backup as a part of recovery
initramfs tooling (no need to setup networking or have ssh or similar
tooling as part of the initramfs). Say we want to backup the disk of
host1 to host2. First Thunderbolt/USB4 cable is connected between the
hosts (there can be devices in the middle too) then the receiving side
configures the stream:
host2 # mkdir /sys/kernel/config/thunderbolt/stream/0-1.0
host2 # mkdir /sys/kernel/config/thunderbolt/stream/0-1.0/backup
host2 # echo -1 > /sys/kernel/config/thunderbolt/stream/0-1.0/backup/in_hopid
host2 # echo -1 > /sys/kernel/config/thunderbolt/stream/0-1.0/backup/out_hopid
We use automatic HopID allocation (writing -1 to HopIDs) for simplicity.
From this point forward the /dev/tbstream0 can be used pretty much as
regular file:
host2 # dd if=/dev/tbstream0 of=/tmp/host1.nvme0n1.backup-$(date +%F) bs=256k
The host that is being backed up then configures the stream accordingly:
host1 # mkdir /sys/kernel/config/thunderbolt/stream/0-503.0
host1 # mkdir /sys/kernel/config/thunderbolt/stream/0-503.0/backup
Here we take advantage of the fact that host2 also announces the active
streams through XDomain properties so the name "backup" gives us the
HopIDs. It is also possible to configure them manually in the same way
we did for host2.
Then it is just a matter of copying the data over:
host1 # dd if=/dev/nvme0n1 of=/dev/tbstream0 bs=256k
Similarly it is possible to transfer parts of the filesystem. For
example copy contents of mydir over to the host2:
host2 # gunzip < /dev/tbstream0 | tar xf -
host1 # tar cf - mydir | gzip > /dev/tbstream0
Other end of the spectrum use-case is "borrowing" laptop (host1) camera
to desktop (host2):
host2 # gst-launch-1.0 filesrc location=/dev/tbstream0 ! jpegdec ! videoconvert ! \
autovideosink
host1 # gst-launch-1.0 v4l2src device=/dev/video0 ! video/x-raw,width=1920,height=1080 ! \
jpegenc quality=90 ! filesink location=/dev/tbstream0
Once the streams are no longer needed they can be removed:
host1 # cd /sys/kernel/config/thunderbolt/stream/
host1 # rmdir -p 0-503.0/backup
host2 # cd /sys/kernel/config/thunderbolt/stream
host2 # rmdir -p 0-1.0/backup
Co-developed-by: Alan Borzeszkowski <alan.borzeszkowski@linux.intel.com>
Signed-off-by: Alan Borzeszkowski <alan.borzeszkowski@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
79 lines
2.6 KiB
Plaintext
79 lines
2.6 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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menuconfig USB4
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tristate "Unified support for USB4 and Thunderbolt"
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depends on PCI
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select APPLE_PROPERTIES if EFI_STUB && X86
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select CRC32
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select CRYPTO_LIB_SHA256
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select CRYPTO_LIB_UTILS
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select NVMEM
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help
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USB4 and Thunderbolt driver. USB4 is the public specification
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based on the Thunderbolt 3 protocol. This driver is required if
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you want to hotplug Thunderbolt and USB4 compliant devices on
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Apple hardware or on PCs with Intel Falcon Ridge or newer.
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To compile this driver a module, choose M here. The module will be
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called thunderbolt.
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if USB4
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config USB4_CONFIGFS
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def_tristate USB4
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depends on CONFIGFS_FS && !(USB4=y && CONFIGFS_FS=m)
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config USB4_DEBUGFS_WRITE
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bool "Enable write by debugfs to configuration spaces (DANGEROUS)"
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help
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Enables writing to device configuration registers through
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debugfs interface. You can use tools such as Thunderbolt/USB4
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debugging tools to access these registers. For more
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information see:
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https://github.com/intel/tbtools
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Only enable this if you know what you are doing! Never enable
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this for production systems or distro kernels.
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config USB4_DEBUGFS_MARGINING
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bool "Expose receiver lane margining operations under USB4 ports and retimers (DANGEROUS)"
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depends on DEBUG_FS
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depends on USB4_DEBUGFS_WRITE
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help
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Enables hardware and software based receiver lane margining
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support under each USB4 port and retimer, including retimers
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on the other side of the cable. Used for electrical quality
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and robustness validation during manufacturing. Should not be
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enabled by distro kernels.
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config USB4_KUNIT_TEST
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bool "KUnit tests" if !KUNIT_ALL_TESTS
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depends on USB4 && KUNIT=y
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default KUNIT_ALL_TESTS
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config USB4_DMA_TEST
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tristate "DMA traffic test driver"
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depends on DEBUG_FS
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help
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This allows sending and receiving DMA traffic through loopback
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connection. Loopback connection can be done by either special
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dongle that has TX/RX lines crossed, or by simply connecting a
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cable back to the host. Only enable this if you know what you
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are doing. Normal users and distro kernels should say N here.
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To compile this driver a module, choose M here. The module will be
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called thunderbolt_dma_test.
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config USB4_STREAM
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tristate "Stream data over Thunderbolt/USB4 cable"
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depends on USB4_CONFIGFS
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help
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This adds support for USB4STREAM protocol that allows two
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hosts to stream data directly over Thunderbolt/USB4 cable
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through /dev/tbstreamX devices.
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To compile this driver a module, choose M here. The module will be
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called thunderbolt_stream.
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endif # USB4
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