[PATCH v1 0/6] misc: amd-sbi: Refactor SBTSI driver with I3C support and ioctl interface

Akshay Gupta
2026-03-23T11:08:39Z

This series refactors the AMD SB-TSI (Side-Band Temperature Sensor
Interface) driver by moving it from the hwmon subsystem into the
drivers/misc/amd-sbi framework, alongside the existing SB-RMI driver.

Background:
The SB-TSI driver currently lives under drivers/hwmon/sbtsi_temp.c and
is limited to exposing temperature readings via the hwmon interface.
As AMD platforms evolve, SB-TSI access is required from multiple
consumers (hwmon, userspace via ioctl, I3C-attached devices), making
the hwmon-only placement insufficient.

This series restructures the driver into a layered design:

- tsi-core.c : core register access and ioctl/miscdevice support
- tsi-hwmon.c : hwmon sensor layer built on top of the core
- tsi.c : I2C/I3C probe and glue

Changes in this series:
1. Move core SBTSI driver from drivers/hwmon into drivers/misc/amd-sbi,
renaming sbtsi_temp.c -> sbtsi.c and wiring it into the amd-sbi
Kconfig/Makefile. The hwmon probe entry point is preserved so
existing device-tree bindings and hwmon consumers are unaffected.

2. Update the Kconfig entry to explicitly state that the driver targets
BMC-side I2C/I3C controllers (ARM/ARM64), avoiding accidental
enablement on non-BMC targets.

3. Split the hwmon sensor handling (sysfs attributes, hwmon_chip_info)
into tsi-hwmon.c so the core transport layer is not entangled with
hwmon internals, making future interface additions cleaner.

4. Extend the driver to support SB-TSI over I3C in addition to I2C.
Both buses share the same core read/write path via sbtsi_xfer();
the is_i3c flag selects the underlying transport at probe time.
Backward compatibility with existing I2C deployments is maintained.

5. Add a miscdevice (/dev/sbtsi-<addr>) and an ioctl interface
(SBTSI_IOCTL_REG_XFER_CMD) that allows root userspace to perform
SB-TSI register read/write operations through the APML protocol,
consistent with the existing SBRMI ioctl interface.

6. Document the new SBTSI miscdevice and its ioctl in
Documentation/misc-devices/amd-sbi.rst.

Testing:
Tested on AMD Genoa/Turin/Venice BMC platforms with both I2C and I3C-attached
SB-TSI targets. hwmon sysfs attributes (tempX_input, tempX_max, etc.)
and ioctl register transfers verified against hardware.

Akshay Gupta (1):
misc: amd-sbi: Update SBTSI Kconfig to clarify this is BMC driver

Prathima (5):
hwmon/misc: amd-sbi: Move core SBTSI support from hwmon to misc
misc: amd-sbi: Split SBTSI hwmon sensor handling into a separate
entity
misc: amd-sbi: Add support for SB-TSI over I3C
misc: amd-sbi: Add SBTSI ioctl register transfer interface
docs: misc: amd-sbi: Document SBTSI userspace interface

Documentation/misc-devices/amd-sbi.rst | 18 ++
drivers/hwmon/Kconfig | 10 -
drivers/hwmon/Makefile | 1 -
drivers/hwmon/sbtsi_temp.c | 250 -------------------------
drivers/misc/amd-sbi/Kconfig | 24 +++
drivers/misc/amd-sbi/Makefile | 4 +
drivers/misc/amd-sbi/tsi-core.c | 146 +++++++++++++++
drivers/misc/amd-sbi/tsi-core.h | 44 +++++
drivers/misc/amd-sbi/tsi-hwmon.c | 198 ++++++++++++++++++++
drivers/misc/amd-sbi/tsi.c | 162 ++++++++++++++++
include/uapi/misc/amd-apml.h | 23 +++
11 files changed, 619 insertions(+), 261 deletions(-)
delete mode 100644 drivers/hwmon/sbtsi_temp.c
create mode 100644 drivers/misc/amd-sbi/tsi-core.c
create mode 100644 drivers/misc/amd-sbi/tsi-core.h
create mode 100644 drivers/misc/amd-sbi/tsi-hwmon.c
create mode 100644 drivers/misc/amd-sbi/tsi.c

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2.34.1