net: mctp: Add MCTP USB transport driver

Add an implementation for DMTF DSP0283, which defines a MCTP-over-USB
transport. As per that spec, we're restricted to full speed mode,
requiring 512-byte tr

net: mctp: Add MCTP USB transport driver

Add an implementation for DMTF DSP0283, which defines a MCTP-over-USB
transport. As per that spec, we're restricted to full speed mode,
requiring 512-byte transfers.

Each MCTP-over-USB interface is a peer-to-peer link to a single MCTP
endpoint, so no physical addressing is required (of course, that MCTP
endpoint may then bridge to further MCTP endpoints). Consequently,
interfaces will report with no lladdr data:

# mctp link
dev lo index 1 address 00:00:00:00:00:00 net 1 mtu 65536 up
dev mctpusb0 index 6 address none net 1 mtu 68 up

This is a simple initial implementation, with single rx & tx urbs, and
no multi-packet tx transfers - although we do accept multi-packet rx
from the device.

Includes suggested fixes and backport reworks from Santosh Puranik
<spuranik@nvidia.com>.

Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Cc: Santosh Puranik <spuranik@nvidia.com>
Link: https://patch.msgid.link/20250221-dev-mctp-usb-v3-2-3353030fe9cc@codeconstruct.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit 0791c0327a6e4e7691d6fc5ad334c215de04dcc9)
[arj: squashed in Santosh's v6.6 rework into the backport]
Link: https://patch.msgid.link/20250507173806.5371-4-santosh.puranik.ibm@gmail.com
Signed-off-by: Santosh Puranik <santosh.puranik.ibm@gmail.com>
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>

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net: mctp i3c: Copy headers if cloned

Use skb_cow_head() prior to modifying the tx skb. This is necessary
when the skb has been cloned, to avoid modifying other shared clones.

Signed-off-by: Matt J

net: mctp i3c: Copy headers if cloned

Use skb_cow_head() prior to modifying the tx skb. This is necessary
when the skb has been cloned, to avoid modifying other shared clones.

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Fixes: c8755b29b58e ("mctp i3c: MCTP I3C driver")
Link: https://patch.msgid.link/20250306-matt-i3c-cow-head-v1-1-d5e6a5495227@codeconstruct.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit 26db9c9ee19c36a97dbb1cfef007a3c189c4c874)
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>

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mctp i3c: handle NULL header address

daddr can be NULL if there is no neighbour table entry present,
in that case the tx packet should be dropped.

saddr will usually be set by MCTP core, but check

mctp i3c: handle NULL header address

daddr can be NULL if there is no neighbour table entry present,
in that case the tx packet should be dropped.

saddr will usually be set by MCTP core, but check for NULL in case a
packet is transmitted by a different protocol.

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Fixes: c8755b29b58e ("mctp i3c: MCTP I3C driver")
Link: https://patch.msgid.link/20250304-mctp-i3c-null-v1-1-4416bbd56540@codeconstruct.com.au
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
(cherry picked from commit cf7ee25e70c6edfac4553d6b671e8b19db1d9573)
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>

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mctp i3c: fix MCTP I3C driver multi-thread issue

We found a timeout problem with the pldm command on our system. The
reason is that the MCTP-I3C driver has a race condition when receiving
multiple-

mctp i3c: fix MCTP I3C driver multi-thread issue

We found a timeout problem with the pldm command on our system. The
reason is that the MCTP-I3C driver has a race condition when receiving
multiple-packet messages in multi-thread, resulting in a wrong packet
order problem.

We identified this problem by adding a debug message to the
mctp_i3c_read function.

According to the MCTP spec, a multiple-packet message must be composed
in sequence, and if there is a wrong sequence, the whole message will be
discarded and wait for the next SOM.
For example, SOM → Pkt Seq #2 → Pkt Seq #1 → Pkt Seq #3 → EOM.

Therefore, we try to solve this problem by adding a mutex to the
mctp_i3c_read function. Before the modification, when a command
requesting a multiple-packet message response is sent consecutively, an
error usually occurs within 100 loops. After the mutex, it can go
through 40000 loops without any error, and it seems to run well.

Fixes: c8755b29b58e ("mctp i3c: MCTP I3C driver")
Signed-off-by: Leo Yang <Leo-Yang@quantatw.com>
Link: https://patch.msgid.link/20250107031529.3296094-1-Leo-Yang@quantatw.com
[pabeni@redhat.com: dropped already answered question from changelog]
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
(cherry picked from commit 2d2d4f60ed266a8f340a721102d035252606980b)
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>

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net: mctp: Expose transport binding identifier via IFLA attribute

MCTP control protocol implementations are transport binding dependent.
Endpoint discovery is mandatory based on transport binding.
M

net: mctp: Expose transport binding identifier via IFLA attribute

MCTP control protocol implementations are transport binding dependent.
Endpoint discovery is mandatory based on transport binding.
Message timing requirements are specified in each respective transport
binding specification.

However, we currently have no means to get this information from MCTP
links.

Add a IFLA_MCTP_PHYS_BINDING netlink link attribute, which represents
the transport type using the DMTF DSP0239-defined type numbers, returned
as part of RTM_GETLINK data.

We get an IFLA_MCTP_PHYS_BINDING attribute for each MCTP link, for
example:

- 0x00 (unspec) for loopback interface;
- 0x01 (SMBus/I2C) for mctpi2c%d interfaces; and
- 0x05 (serial) for mctpserial%d interfaces.

Signed-off-by: Khang Nguyen <khangng@os.amperecomputing.com>
Reviewed-by: Matt Johnston <matt@codeconstruct.com.au>
Link: https://patch.msgid.link/20241105071915.821871-1-khangng@os.amperecomputing.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit 580db513b4a9d52f306580015a1872eea0a0894e)
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>

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Merge tag 'v6.6.84' into for/openbmc/dev-6.6

This is the 6.6.84 stable release

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Merge tag 'v6.6.84' into for/openbmc/dev-6.6

This is the 6.6.84 stable release

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# gpg: Signature made Sun 23 Mar 2025 06:23:17 ACDT
# gpg: using RSA key 647F28654894E3BD457199BE38DBBDC86092693E
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# gpg: gregkh@kernel.org: Verified 13 signatures in the past 8 weeks. Encrypted
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# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg: It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 647F 2865 4894 E3BD 4571 99BE 38DB BDC8 6092 693E

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