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 V5:

- period_tick is now capped to U32_MAX to avoid breaking
  monotonicity
- period_ticks less than 2 are set to 2
- fixed two casts in fromhw() that could led to an incorrect
  truncation/underflow
- when disabling a pwm channel, first set the polarity to
  avoid unintended quiescent level
- in probe function, fixed and error path that could leak
  an invalid pwm_chip struct


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  |   9 +
 drivers/pwm/Kconfig                           |   9 +
 drivers/pwm/Makefile                          |   1 +
 drivers/pwm/pwm-rp1.c                         | 424 ++++++++++++++++++
 6 files changed, 509 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