This adds a generic MCTP endpoint model that other devices may derive
from.

Also included is a very basic implementation of an NVMe-MI device,
supporting only a small subset of the required commands.

Since this all relies on i2c target mode, this can currently only be
used with an SoC that includes the Aspeed I2C controller.

The easiest way to get up and running with this, is to grab my buildroot
overlay[1] (aspeed_ast2600evb_nmi_defconfig). It includes modified a
modified dts as well as a couple of required packages.

QEMU can then be launched along these lines:

  qemu-system-arm \
    -nographic \
    -M ast2600-evb \
    -kernel output/images/zImage \
    -initrd output/images/rootfs.cpio \
    -dtb output/images/aspeed-ast2600-evb-nmi.dtb \
    -nic user,hostfwd=tcp::2222-:22 \
    -device nmi-i2c,address=0x3a \
    -serial mon:stdio

From within the booted system,

  mctp addr add 8 dev mctpi2c15
  mctp link set mctpi2c15 up
  mctp route add 9 via mctpi2c15
  mctp neigh add 9 dev mctpi2c15 lladdr 0x3a
  mi-mctp 1 9 info

Comments are very welcome!

  [1]: https://github.com/birkelund/hwtests/tree/main/br2-external

Changes since v3
~~~~~~~~~~~~~~~~

  - Inlined the POLY define in the crc8 function (Philippe)
  - Changed a bunch of fields to use registerfields.h

  - From Jonathan:
    + Added references to specs defining the structures.

  - From Corey:
    + Reworked the buffer handling (again) ;)
      Derived devices can now never write into the mctp core buffers. Instead,
      the mctp core will request a buffer pointer and copy from there.
      Internally, within the mctp core, writes to internal buffers are also
      checked.

Changes since v2
~~~~~~~~~~~~~~~~

  - Applied a bunch of feedback from Jonathan:
    + Moved a lot of internally used structs out of the include headers
      and into the source files.
    + Added spec references in various places
    + Split the patch for i2c_smbus_pec() into its own
    + Fix a compile error (and bug) in nmi-i2c.c.

  - From Corey:
    + Reworked the buffer handling. The deriving devices now returns a
      pointer to their own buffer that the mctp core copies into.
    + Added a couple of extra debugging trace events.

Changes since v1
~~~~~~~~~~~~~~~~

  - Fix SPDX-License tag for hw/nvme/nmi-i2c.c (Philippe)
  - Add some asserts to verify buffer indices (by request from Corey).
  - Drop short packets that could result in underflow (Corey)
  - Move i2c_smbus_pec() to smbus common code (Corey)
  - A couple of logic fixes (patch from Jeremy squashed in)
  - Added a patch to handle messages with dest eid 0 (Matt)
    Maybe squash this as well.

Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
---
Klaus Jensen (3):
      hw/i2c: add smbus pec utility function
      hw/i2c: add mctp core
      hw/nvme: add nvme management interface model

 MAINTAINERS                   |   7 +
 hw/arm/Kconfig                |   1 +
 hw/i2c/Kconfig                |   4 +
 hw/i2c/mctp.c                 | 428 ++++++++++++++++++++++++++++++++++++++++++
 hw/i2c/meson.build            |   1 +
 hw/i2c/smbus_master.c         |  26 +++
 hw/i2c/trace-events           |  13 ++
 hw/nvme/Kconfig               |   4 +
 hw/nvme/meson.build           |   1 +
 hw/nvme/nmi-i2c.c             | 418 +++++++++++++++++++++++++++++++++++++++++
 hw/nvme/trace-events          |   6 +
 include/hw/i2c/mctp.h         | 127 +++++++++++++
 include/hw/i2c/smbus_master.h |   2 +
 include/net/mctp.h            |  35 ++++
 14 files changed, 1073 insertions(+)
---
base-commit: b0dd9a7d6dd15a6898e9c585b521e6bec79b25aa
change-id: 20230822-nmi-i2c-d804ed5be7e6

Best regards,
-- 
Klaus Jensen <k.jensen@samsung.com>