[PATCH v5 0/4] hwmon: Add Kandou KB9002 PCIe retimer driver

[Andy Chung via B4 Relay <devnull+Andy.Chung.amd.com@kernel.org>]

The Kandou KB9002 is an 8-lane PCIe 5.0 retimer with an integrated
microcontroller that exposes an SMBus 3.0 target (with mandatory PEC)
on its sideband interface. Its firmware aggregates per-lane die
temperatures and publishes the maximum through a register window.

This series adds a hwmon driver for it. The driver reports the
aggregated maximum die temperature as temp1_input, and exposes the
running firmware version and boot status under debugfs.

The series is organised as:

  1/4  add the "kandou" vendor prefix
  2/4  trivial-devices entry for the retimer
  3/4  the driver, Kconfig/Makefile and MAINTAINERS entry
  4/4  hwmon documentation

Signed-off-by: Andy Chung <Andy.Chung@amd.com>
---
Changes in v5:
- Resend; v4 did not fully reach the lists.
- Fix the patch 1 commit message to say "Kandou AI", matching the
  vendor-prefix description.

Changes in v4:
- dt-bindings: move the binding into trivial-devices.yaml; the device
  has no device-specific properties beyond its address.
- dt-bindings: describe the vendor prefix as "Kandou AI", the current
  company name.
- Document the register endianness at the top of the driver.
- Simplify kb9002_is_visible() to return 0444.
- Drop the temp1_label attribute; the chip name is already exposed via
  the hwmon "name" attribute.
- Link to v3: https://lore.kernel.org/all/20260721-kb9002-upstream-v3-0-70563922be8d@amd.com

Changes in v3:
- Drop the private register-access mutex. The temperature read is
  already serialised by the hwmon core lock; the debugfs files
  (fw_ver, fw_load_status) now take hwmon_lock() to serialise
  against it, since they are read outside the core lock.
- Use a named initialiser for the i2c_device_id entry.
- dt-bindings: constrain the reg address range under 'items' rather
  than applying minimum/maximum to the array.
- Link to v2: https://patch.msgid.link/20260715-kb9002-upstream-v2-0-2fd390383da5@amd.com

Changes in v2:
- Drop the unconditional I2C_FUNC_I2C requirement at probe; require raw
  I2C only in the host-interface switch path, so the driver loads on
  SMBus-only adapters when the chip is already strapped to SMBus.
- kb9002_read_revid(): return immediately on a hard I2C read error
  instead of retrying the FIFO drain, avoiding needless bus traffic when
  the device is absent.
- Link to v1: https://lore.kernel.org/all/20260714-kb9002-upstream-v1-0-8fd2f0b135d8@amd.com

---
Andy Chung (4):
      dt-bindings: Add vendor prefix for Kandou
      dt-bindings: trivial-devices: Add Kandou KB9002
      hwmon: (kb9002) Add driver for Kandou KB9002 retimer
      hwmon: (kb9002) Add documentation

 .../devicetree/bindings/trivial-devices.yaml       |   2 +
 .../devicetree/bindings/vendor-prefixes.yaml       |   2 +
 Documentation/hwmon/index.rst                      |   1 +
 Documentation/hwmon/kb9002.rst                     |  64 +++
 MAINTAINERS                                        |   7 +
 drivers/hwmon/Kconfig                              |  11 +
 drivers/hwmon/Makefile                             |   1 +
 drivers/hwmon/kb9002.c                             | 460 +++++++++++++++++++++
 8 files changed, 548 insertions(+)
---
base-commit: ca078d004cf58137bcf8cb24a8b271397431ba58
change-id: 20260713-kb9002-upstream-06c686e37833

Best regards,
--  
Andy Chung <Andy.Chung@amd.com>