scsi: mpt3sas: Add hwmon support

Expose the IOC and board temperature sensors of LSI / Broadcom SAS HBAs
through hwmon. Readings come from MPI IO Unit Page 7 via the accessor added
in the preceding patch.

The same fields are exposed by Broadcom's userspace tooling through the
/dev/mpt[23]ctl ioctl path (typically root-only): IOCTemperature and
BoardTemperature in lsiutil; ROC and Controller in storcli. With this
driver, sensors(1) shows them unprivileged:

  $ sensors mpt3sas-pci-0200
  mpt3sas-pci-0200
  Adapter: PCI adapter
  IOC:          +42.0°C

Each channel is gated independently by its *TemperatureUnits field through
is_visible(); cards that populate only one sensor expose only one input
file, and cards that populate neither do not register an hwmon device.

The hwmon code is gated directly on CONFIG_HWMON. IS_REACHABLE() is used
rather than IS_ENABLED() so that SCSI_MPT3SAS=y with HWMON=m still builds;
in that configuration, the sensors are not exposed (same pattern as i915
and xe).

Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Louis Sautier <sautier.louis@gmail.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://patch.msgid.link/20260630224922.2543096-3-sautier.louis@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

0 files changed, 0 insertions, 0 deletions