[PATCH v1 0/3] raw/ntb: add AMD NTB support

[Raghavendra Ningoji]

This series adds support for the Non-Transparent Bridge (NTB) endpoints
integrated in AMD EPYC Embedded "Turin", "Genoa" and "Siena" processors
to the raw/ntb driver.

The NTB rawdev framework was originally written around the Intel
back-to-back topology and the built-in scratchpad handshake protocol.
Patch 1 generalizes it with a few vendor-neutral hooks so other vendors
can reuse the common code; the Intel driver is unaffected since the new
hooks fall back to the built-in paths when NULL. Patch 2 adds the AMD
hardware driver, and patch 3 documents the new support.

A few AMD-specific hardware details worth noting for reviewers:

- Primary/secondary topology. One endpoint enumerates as the primary
  (device ID 0x14c0) and the other as the secondary (0x14c3), rather
  than the Intel back-to-back model.

- Packed scratchpad handshake. The hardware exposes a single shared
  16-register scratchpad bank split into two disjoint 8-register sets
  (one per side), so the driver uses a packed handshake layout that
  fits in 8 registers, plugged in through the dev_handshake and
  read_peer_config hooks.

- Outbound translation window. AMD NTB uses an outbound translation
  window: a write to a BARxx memory-window offset is forwarded to
  (xlat_base | offset) in the peer's memory rather than
  (xlat_base + offset). The translation base must therefore be aligned
  to a power of two >= the window length so that no offset bit collides
  with a set bit in the base. This is reported to applications through a
  new mw_addr_align field in struct ntb_dev_info and honoured by the ntb
  example when reserving the memory window memzone.

- Secondary-side link status. On the secondary side the device's own
  PCIe link status does not reflect the true inter-host link, so the
  speed and width are read from the upstream switch port via sysfs.

Tested on a two-node setup (primary + secondary EPYC Embedded hosts)
with the dpdk-ntb example: the link comes up at the expected speed and
width on both sides, and file transfers are byte-correct end to end for
both small and large files.

Raghavendra Ningoji (3):
  raw/ntb: generalize framework for multiple vendors
  raw/ntb: add AMD NTB support
  doc: add AMD NTB support

 MAINTAINERS                            |   1 +
 doc/guides/rawdevs/ntb.rst             |  18 +-
 doc/guides/rel_notes/release_26_11.rst |   8 +
 drivers/raw/ntb/meson.build            |   3 +-
 drivers/raw/ntb/ntb.c                  | 115 ++--
 drivers/raw/ntb/ntb.h                  |  18 +
 drivers/raw/ntb/ntb_hw_amd.c           | 709 +++++++++++++++++++++++++
 drivers/raw/ntb/ntb_hw_amd.h           | 114 ++++
 drivers/raw/ntb/rte_pmd_ntb.h          |  10 +
 examples/ntb/ntb_fwd.c                 |  22 +-
 usertools/dpdk-devbind.py              |   4 +-
 11 files changed, 985 insertions(+), 37 deletions(-)
 create mode 100644 drivers/raw/ntb/ntb_hw_amd.c
 create mode 100644 drivers/raw/ntb/ntb_hw_amd.h

-- 
2.34.1