[PATCH v2 0/7] thermal: samsung: Add support for Google GS101 TMU

Tudor Ambarus
2026-01-19T12:08:54Z

Add support for the Thermal Management Unit (TMU) on the Google GS101
SoC.

The GS101 TMU implementation utilizes a hybrid architecture where
management is shared between the kernel and the Alive Clock and
Power Manager (ACPM) firmware.

Dependencies
============

- firmware patches 2, 3: required by the thermal driver (patch 4).
- bindings (patch 1): required for DTS validation.
- thermal driver patch 4: required by defconfig (patch 7) - logical
dependency.

Given the thermal driver is a new addition, I suggest everything to go
through the Samsung SoC tree, with ACKs from the Thermal maintainers.

If the Thermal maintainers prefer to take the bindings and the thermal
driver patches via their tree we'll need:
- an immutable branch containing the firmware patches (2 and 3) from the
Samsung SoC tree to serve as a base for the thermal driver.
- an immutable branch containing the bindings and the thermal driver
from the thermal tree to serve as a base for the dts and defconfig.

Architecture Overview
=====================

The hardware supports two parallel control paths. For this
implementation, responsibilities are split as follows:

1. Kernel Responsibility:
- maintain direct memory-mapped access to the interrupt pending
(INTPEND) registers to identify thermal events.
- map physical hardware interrupts to logical thermal zones.
- coordinate functional operations through the ACPM IPC protocol.

2. Firmware Responsibility (ACPM):
- handle sensor initialization and calibration.
- manage thermal thresholds and hysteresis configuration.
- perform temperature acquisition and expose data via IPC.

Sensor Mapping (One-to-Many)
============================

The SoC contains multiple physical temperature sensors, but the ACPM
firmware abstracts these into logical groups (Clusters) for reporting:

- ACPM Sensor 0 (Big Cluster): Aggregates physical sensors 0, 6, 7, 8, 9.
- ACPM Sensor 1 (Mid Cluster): Aggregates physical sensors 4, 5.
- ACPM Sensor 2 (Little Cluster): Aggregates physical sensors 1, 2.

The driver maps physical interrupt bits back to these logical parents.
When an interrupt fires, the driver checks the bitmask in the INTPEND
registers and updates the corresponding logical thermal zone.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
---
Changes in v2:
- architecture: switch from a syscon/MFD approach to a thermal-sensor
node with a phandle to the ACPM interface
- bindings: address Krzysztof's feedback, drop redundencies,
interrupts description.
- firmware: introduce devm_acpm_get_by_phandle() to standardize IPC
handle acquisition.
- thermal driver: drop compatible's data and use the static data from
the driver directly.
- defconfig, make EXYNOS_ACPM_THERMAL a module
- Link to v1: https://lore.kernel.org/r/20260114-acpm-tmu-v1-0-cfe56d93e90f@linaro.org

---
Tudor Ambarus (7):
dt-bindings: thermal: Add Google GS101 TMU
firmware: samsung: acpm: Add TMU protocol support
firmware: samsung: acpm: Add devm_acpm_get_by_phandle helper
thermal: samsung: Add support for GS101 TMU
MAINTAINERS: Add entry for Samsung Exynos ACPM thermal driver
arm64: dts: exynos: gs101: Add thermal management unit
arm64: defconfig: enable Exynos ACPM thermal support

.../bindings/thermal/google,gs101-tmu-top.yaml | 67 +++
MAINTAINERS | 8 +
arch/arm64/boot/dts/exynos/google/gs101-tmu.dtsi | 209 +++++++
arch/arm64/boot/dts/exynos/google/gs101.dtsi | 18 +
arch/arm64/configs/defconfig | 1 +
drivers/firmware/samsung/Makefile | 1 +
drivers/firmware/samsung/exynos-acpm-tmu.c | 212 +++++++
drivers/firmware/samsung/exynos-acpm-tmu.h | 33 ++
drivers/firmware/samsung/exynos-acpm.c | 35 ++
drivers/thermal/samsung/Kconfig | 16 +
drivers/thermal/samsung/Makefile | 2 +
drivers/thermal/samsung/acpm-tmu.c | 643 +++++++++++++++++++++
.../linux/firmware/samsung/exynos-acpm-protocol.h | 30 +
13 files changed, 1275 insertions(+)
---
base-commit: e2211f5d980086dd9fbdab3bcd86b715e12cae13
change-id: 20260113-acpm-tmu-27e21f0e2c3b

Best regards,
--
Tudor Ambarus <tudor.ambarus@linaro.org>