[PATCH v2 0/3] Add RP1 PWM controller support

Andrea della Porta
2026-04-10T14:07:02Z

This patchset adds support for the PWM controller found on the
Raspberry Pi RP1 southbridge. This is necessary to operate the
cooling fan connected to one of the PWM channels.

The tachometer pin for the fan speed is managed by the firmware
running on the RP1's M-core. It uses the PHASE2 register
to report the RPM, which is then exported by this driver via
syscon registers. A subsequent patch will add a new device
and driver to read the RPM and export this value via hwmon.

Subsequent patches will also add the CPU thermal zone, which
acts as a consumer of the PWM device.

Best regards,
Andrea

CHANGES in V2:

- bindings: added syscon to the description
- bindings: changed additionalProperties to unevaluatedProperties
- dts: reordered pwm node to follow the unit address ordering
- Kconfig/Makefile: renamed config option to PWM_RASPBERRYPI_RP1
- Kconfig: added dependency for syscon/regmap
- driver: added 'Limitations' and 'Datasheet' paragraphs in top comment
- driver: all macros are now prefixed by RP1_PWM_
- driver: implemented waveform callbacks instead of legacy ones
- driver: dropped hwmon device registration for fan speed (this will be
handled in a separate patch with its own driver reading the value via
syscon)
- driver: added new regmap/syscon to export the registers.
- driver: added a comment in rp1_pwm_apply_config() to describe what it does
- driver: added a comment to rp1_pwm_request() to define the purpose of the
last write
- driver: new clk_enabled flag to deal with the clock on suspend/resume path
- driver: clk_rate is now obtained during probe right after exclusive_get()
- driver/Kconfig: module is now static only and has suppress_bind_attr to
avoid racing with syscon consumer drivers and with syscon unload issue

Naushir Patuck (2):
dt-bindings: pwm: Add Raspberry Pi RP1 PWM controller
pwm: rp1: Add RP1 PWM controller driver

Stanimir Varbanov (1):
arm64: dts: broadcom: rpi-5: Add RP1 PWM node

.../bindings/pwm/raspberrypi,rp1-pwm.yaml | 54 +++
.../boot/dts/broadcom/bcm2712-rpi-5-b.dts | 12 +
arch/arm64/boot/dts/broadcom/rp1-common.dtsi | 10 +
drivers/pwm/Kconfig | 9 +
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-rp1.c | 344 ++++++++++++++++++
6 files changed, 430 insertions(+)
create mode 100644 Documentation/devicetree/bindings/pwm/raspberrypi,rp1-pwm.yaml
create mode 100644 drivers/pwm/pwm-rp1.c

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2.35.3