linux-kernel - [PATCH v2 0/3] Add the System Timer Module counter

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Message-ID: <20251210052449.4154283-1-daniel.lezcano@linaro.org>
Date: Wed, 10 Dec 2025 06:24:44 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: wbg@...nel.org,
	robh@...nel.org,
	conor+dt@...nel.org,
	krzk+dt@...nel.org
Cc: s32@....com,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-iio@...r.kernel.org
Subject: [PATCH v2 0/3] Add the System Timer Module counter

The NXP S32 family provides a System Timer Module (STM), a 32-bit
free-running counter clocked from a peripheral clock. The STM includes
a prescaler and one or more compare channels generating optional
interrupts. When used as a generic hardware counter, only the main
free-running counter is required, while the compare channels are
typically unused.

On S32G2 devices, the STM is exposed as a simple counter block that
can operate continuously and be shared across subsystems such as the
Linux kernel, firmware components running on Cortex-M7 cores, or other
co-processors. The counter can be read atomically and provides a
stable timestamp source to correlate events occurring in different
execution contexts.

The Linux kernel controls the STM through a memory-mapped interface,
configuring the prescaler, enabling or disabling the counter, and
accounting for wrap-arounds. Other subsystems access the counter in
read-only mode, making it a shared timestamp reference across the
platform.

This driver adds support for the STM when used as a counter on S32G2
platforms. The device is described in the device tree using the
following compatible:

compatible = "nxp,s32g2-stm-cnt";

The driver exposes basic counter functionality: start, stop, reset,
prescaler configuration, and overflow handling.

Changelog:
	* v2
	  - Added Rob's tag
	  ** kbuild
	  - Reordered alphabetically the headers
	  - Added bitfield.h header
	  - Use DEFINE_SIMPLE_DEV_PM_OPS() and pm_sleep_ptr()

Daniel Lezcano (3):
  counters: Reorder the Makefile
  dt-bindings: counter: Add NXP System Timer Module Counter
  counter: Add STM based counter

 .../bindings/counter/nxp,s32g2-stm-cnt.yaml   |  64 +++
 drivers/counter/Kconfig                       |  10 +
 drivers/counter/Makefile                      |  21 +-
 drivers/counter/nxp-stm-cnt.c                 | 386 ++++++++++++++++++
 4 files changed, 472 insertions(+), 9 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/counter/nxp,s32g2-stm-cnt.yaml
 create mode 100644 drivers/counter/nxp-stm-cnt.c

-- 
2.43.0