[PATCH v4 00/11] thermal: samsung: Add support for Google GS101 TMU

Tudor Ambarus
2026-04-23T15:23:00Z

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. This hybrid ACPM TMU architecture is
also present on other Samsung Exynos SoCs (e.g., AutoV920, Exynos850).

Dependencies
============
- context dependency on the ACPM fixes sent at:
Link: https://lore.kernel.org/linux-samsung-soc/20260423-acpm-fixes-sashiko-reports-v1-0-2217b790925e@linaro.org/T/#t
- cleanup and prep firmware patches 2, 3, 4, 5, 6, 7: required by the
thermal driver (patch 8).
- bindings (patch 1): required for DTS validation.
- thermal driver patch 8: required by defconfig (patch 11) - 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.
The MFD and clk maintainers are included because of the cleanup patches
(4 and 5). ACPM updated some structures that the mfd and clk client
drivers are using, so these patches shall naturally go via the Samsung
SoC tree.

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 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.
- manage thermal thresholds 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 v4: address sashiko review:
- thermal driver: avoid mixing mutex cleanup helpers with goto statements
- firmware, tmu:
- remove __packed from union acpm_tmu_msg.
- return ERR_PTR(-ENODEV) for devm_acpm_get_by_phandle when
CONFIG_EXYNOS_ACPM_PROTOCOL is disabled.
- Link to v3: https://lore.kernel.org/r/20260420-acpm-tmu-v3-0-3dc8e93f0b26@linaro.org

Changes in v3:
- thermal driver: use .set_trips() instead of .set_trip_point()
- new cleaning/prerequisite patches for firmware/acpm:
- firmware: samsung: acpm: Make acpm_ops const and access via pointer
- firmware: samsung: acpm: Drop redundant _ops suffix in acpm_ops members
- firmware: samsung: acpm: Consolidate transfer initialization helper
- firmware: acpm: TMU helpers - check return value from the firmware
- overall change: emphasize that the ACPM TMU hibrid approach applies to
other Samsung SoCs as well (Exynos850, AutoV920).
- dts: drop active trip points, update trip point values
- collect R-b tags
- Link to v2: https://lore.kernel.org/r/20260119-acpm-tmu-v2-0-e02a834f04c6@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 (11):
dt-bindings: thermal: Add Google GS101 TMU
firmware: samsung: acpm: Consolidate transfer initialization helper
firmware: samsung: acpm: Annotate rx_data->cmd with __counted_by_ptr
firmware: samsung: acpm: Drop redundant _ops suffix in acpm_ops members
firmware: samsung: acpm: Make acpm_ops const and access via pointer
firmware: samsung: acpm: Add TMU protocol support
firmware: samsung: acpm: Add devm_acpm_get_by_phandle helper
thermal: samsung: Add Exynos ACPM TMU driver GS101
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 | 68 +++
MAINTAINERS | 8 +
arch/arm64/boot/dts/exynos/google/gs101-tmu.dtsi | 136 +++++
arch/arm64/boot/dts/exynos/google/gs101.dtsi | 18 +
arch/arm64/configs/defconfig | 1 +
drivers/clk/samsung/clk-acpm.c | 8 +-
drivers/firmware/samsung/Makefile | 1 +
drivers/firmware/samsung/exynos-acpm-dvfs.c | 20 +-
drivers/firmware/samsung/exynos-acpm-pmic.c | 20 +-
drivers/firmware/samsung/exynos-acpm-tmu.c | 240 +++++++++
drivers/firmware/samsung/exynos-acpm-tmu.h | 28 ++
drivers/firmware/samsung/exynos-acpm.c | 113 +++--
drivers/firmware/samsung/exynos-acpm.h | 2 +
drivers/mfd/sec-acpm.c | 6 +-
drivers/thermal/samsung/Kconfig | 17 +
drivers/thermal/samsung/Makefile | 2 +
drivers/thermal/samsung/acpm-tmu.c | 547 +++++++++++++++++++++
.../linux/firmware/samsung/exynos-acpm-protocol.h | 32 +-
18 files changed, 1195 insertions(+), 72 deletions(-)
---
base-commit: 2e68039281932e6dc37718a1ea7cbb8e2cda42e6
change-id: 20260113-acpm-tmu-27e21f0e2c3b
prerequisite-change-id: 20260423-acpm-fixes-sashiko-reports-ae28b6ed5581:v1
prerequisite-patch-id: 18d89d0e2bc0efe2cb366746ac4db36f4682f061
prerequisite-patch-id: eb4f90add371877a1930c442c5464c4da7242889
prerequisite-patch-id: 021cd1ee6d2b93f554dd5098cd1158977294dc41
prerequisite-patch-id: b5da16b5c6d6731ea519ed68302fd52ce57c7ffa

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