[PATCH v9 0/3] Add RP1 PWM controller support

[Andrea della Porta]

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
a function. 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 V9:

All changes are in response of Sashiko's review (where applicable),
see:
https://lore.kernel.org/all/20260908132302.358D91F00ADB@xxxxxxxxxxxxxxx/#t

- linux/bitfield.h is now explicitly included to avoid compile
  time issue related to header refactory
- synchronized the exported function to read the tachometer with
  respect to both the system PM ops and the driver unbind/unload
- reworked the error path of all functions using regmap_read. As
  a consequence, rp1_pwm_apply_config() now returns and int for
  the error.
- made u32 cast explicit for the divisor of DIV_ROUND_UP_ULL
- moved teh struct initializer in rp1_pwm_read_waveform() to the
  top of the function to avoid overwriting part of the resulting
  data.
- dropped suppress_bind_attrs flag and replaced builtin_platform_driver()
  with module_platform_driver((), since the driver can now be
  unbound/unloaded.

Link to V8:
https://lore.kernel.org/all/cover.1788872294.git.andrea.porta@xxxxxxxx/


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     |  66 +++
 .../boot/dts/broadcom/bcm2712-rpi-5-b.dts     |  12 +
 arch/arm64/boot/dts/broadcom/rp1-common.dtsi  |   9 +
 drivers/pwm/Kconfig                           |   8 +
 drivers/pwm/Makefile                          |   1 +
 drivers/pwm/pwm-rp1.c                         | 499 ++++++++++++++++++
 include/soc/bcm2835/raspberrypi-pwm-rp1.h     |  10 +
 7 files changed, 605 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/raspberrypi,rp1-pwm.yaml
 create mode 100644 drivers/pwm/pwm-rp1.c
 create mode 100644 include/soc/bcm2835/raspberrypi-pwm-rp1.h

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2.35.3