Re: [PATCH 00/19] Initial USB4/Thunderbolt support for Apple M1/M2/M3 SoCs

["Joshua Peisach" <jpeisach@ubuntu.com>]

On Sun Aug 30, 2026 at 4:19 PM EDT, Sven Peter wrote:
> Hi,
>
> This series adds initial USB4/Thunderbolt support for Apple Silicon
> M1, M2 and M3 SoCs. Each USB4 capable Type-C port comes with an ACIO
> ("Apple Converged I/O") block which contains a Cortex-M3 co-processor
> and the hardware implementing the USB4 router.
>
> The NHI and DART IOMMU are part of this ACIO block as well. Instead of
> being exposed as independent always-accessible devices the main SoC bus
> only gets a 16 MiB window into ACIO's MMIO space while its co-processor
> is running. It is not entirely clear whether this is ACIO's own address
> space or a window into the co-processor's address space.
>
> This is why the device tree represents the NHI and DART as children of
> ACIO with addresses relative to that window. The driver only populates
> these children after booting the co-processor and removes them again
> before powering ACIO down. This setup is slightly unusual but matches
> both the MMIO layout and the lifetime of the devices.
>
> ACIO also has rather strict ordering requirements: it can only be
> started after the Type-C PHY has been configured for USB4/Thunderbolt
> and has to be stopped again before the PHY is powered down. It also
> needs cable details which are only known to the Type-C port controller.
> The existing Type-C mode switch cannot express the required reverse
> teardown order, so the first three patches add a separate Thunderbolt
> switch and hook it up to the CD321x port controller.
>
> The next two patches add the bindings for the NHI and ACIO. The
> following patches then prepare the Thunderbolt core for the slightly
> different NHI register layout and interrupt handling, read the USB4
> router DROM from the device tree and add quirks for functionality not
> implemented by the Apple hardware.
>
> The main driver powers up ACIO, boots the co-processor, populates
> the DART and NHI children once their MMIO regions are accessible and
> registers the NHI with the software connection manager. The last three
> patches add the device tree nodes for the M1 and M2. M3 nodes will follow
> once the rest of the stack is upstream, but the current Thunderbolt/USB4
> code has already been successfully tested on those.
>
> Right now only XDomain connections and USB3-via-USB4 tunnels are
> supported. Both PCIe and DisplayPort tunnels will come later since those
> require additional work and reverse engineering that is not done yet.
> Suspend is also not supported yet and we actually have to prevent
> suspending whenever an active connection is present because we would
> otherwise resume into an SError.
>
> This series depends on the Apple CIO reset controller [1], the ATCPHY
> USB3-via-4 pipehandler support [2] and support for specifying the DART DMA
> aperture in the device tree [3], a fix for CD321x Thunderbolt
> altmode VDOs [4], and fixes for making the DPTX capabilities read fail
> gracefully [5]. I couldn't split it any further since the remaining
> patches now directly depend upon each other.
> Except for the dts changes the series applies cleanly without these
> dependencies though.
>
> For merging it probably makes most sense if all of this (except for the
> DTS changes) is taken through the thunderbolt tree once everything's been
> reviewed.
>
> Best,
>
> Sven
>
> [1] https://patch.msgid.link/20260821-b4-cio-reset-v2-0-2d045f80a424@kernel.org
> [2] https://patch.msgid.link/20260821-b4-atcphy-usb4-v1-0-45c0b741e0c0@kernel.org
> [3] https://patch.msgid.link/20260819-iommu-apple-dart-aperture-v1-0-252703f381aa@jannau.net
> [4] https://patch.msgid.link/20260813-b4-tipd-vdo-fix-v1-1-70317f2cd554@kernel.org
> [5] https://patch.msgid.link/20260829-b4-tbt-fixes-v3-0-e1fab6ac54fe@kernel.org
>
> Signed-off-by: Sven Peter <sven@kernel.org>
> ---
> Sven Peter (19):
>       dt-bindings: usb: Add thunderbolt-switch property
>       usb: typec: Add thunderbolt switch
>       usb: typec: tipd: Hook up Thunderbolt switch for CD321x
>       dt-bindings: thunderbolt: Add Apple USB4/Thunderbolt NHI
>       dt-bindings: thunderbolt: Add Apple USB4/Thunderbolt ACIO block
>       thunderbolt: Try reading host DROM from device tree first
>       thunderbolt: Don't read the UID if we already know it
>       thunderbolt: Allocate ring HopID before requesting the ring interrupt
>       thunderbolt: Add ring_interrupt_active to tb_nhi_ops
>       thunderbolt: Make the ring register layout configurable
>       thunderbolt: Add ring_interrupt_mask to tb_nhi_ops
>       thunderbolt: Add ring_configure to tb_nhi_ops
>       thunderbolt: Add QUIRK_NO_DMA_PORT
>       thunderbolt: Add QUIRK_NO_USB3_BW_ALLOC
>       thunderbolt: Export symbols required by the Apple Silicon driver
>       thunderbolt: Add Apple Silicon support
>       arm64: dts: apple: t8103: Add USB4 ACIO and NHI
>       arm64: dts: apple: t8112: Add USB4 ACIO and NHI
>       arm64: dts: apple: t60xx: Add USB4 ACIO and NHI
>
>  .../thunderbolt/apple,t8103-usb4-acio.yaml         |  218 +++++
>  .../bindings/thunderbolt/apple,t8103-usb4-nhi.yaml |  151 +++
>  .../devicetree/bindings/usb/usb-switch.yaml        |    6 +
>  MAINTAINERS                                        |    4 +
>  arch/arm64/boot/dts/apple/t6002-j375d.dts          |   67 ++
>  arch/arm64/boot/dts/apple/t600x-dieX.dtsi          |  384 ++++++++
>  arch/arm64/boot/dts/apple/t600x-j314-j316.dtsi     |  107 ++
>  arch/arm64/boot/dts/apple/t600x-j375.dtsi          |  137 +++
>  arch/arm64/boot/dts/apple/t6022-j180d.dts          |  202 ++++
>  arch/arm64/boot/dts/apple/t6022-j475d.dts          |   10 +
>  arch/arm64/boot/dts/apple/t6022-jxxxd.dtsi         |   57 ++
>  arch/arm64/boot/dts/apple/t602x-dieX.dtsi          |  384 ++++++++
>  arch/arm64/boot/dts/apple/t8103-jxxx.dtsi          |   61 ++
>  arch/arm64/boot/dts/apple/t8103.dtsi               |  188 ++++
>  arch/arm64/boot/dts/apple/t8112-jxxx.dtsi          |   61 ++
>  arch/arm64/boot/dts/apple/t8112.dtsi               |  190 ++++
>  drivers/thunderbolt/Kconfig                        |   13 +
>  drivers/thunderbolt/Makefile                       |    3 +
>  drivers/thunderbolt/apple.c                        | 1028 ++++++++++++++++++++
>  drivers/thunderbolt/cap.c                          |    2 +
>  drivers/thunderbolt/ctl.c                          |    2 +
>  drivers/thunderbolt/domain.c                       |    2 +
>  drivers/thunderbolt/eeprom.c                       |   32 +-
>  drivers/thunderbolt/nhi.c                          |  132 ++-
>  drivers/thunderbolt/nhi.h                          |   32 +
>  drivers/thunderbolt/switch.c                       |   19 +-
>  drivers/thunderbolt/tb.c                           |   18 +
>  drivers/thunderbolt/tb.h                           |    5 +
>  drivers/thunderbolt/tunnel.c                       |   59 +-
>  drivers/usb/typec/mux.c                            |  201 ++++
>  drivers/usb/typec/mux.h                            |   12 +
>  drivers/usb/typec/tipd/core.c                      |   37 +
>  include/linux/thunderbolt.h                        |    3 +
>  include/linux/usb/typec_mux.h                      |  114 +++
>  34 files changed, 3872 insertions(+), 69 deletions(-)
> ---
> base-commit: 78bb208b99e7d3314f670710fa9ee0a793682bca
> change-id: 20260829-b4-apple-soc-tbt-a00e873a52db
>
> Best regards,
> --  
> Sven Peter <sven@kernel.org>

I unfortunately cannot test (afaik I do not have the devices) but a
glance over everything seems reasonable :)

Reviewed-by: Joshua Peisach <jpeisach@ubuntu.com>