dts/bindings/pwm/infineon,xmc4xxx-ccu4-pwm.yaml

# Copyright (c) 2023 SLB
# SPDX-License-Identifier: Apache-2.0

description: |
  Infineon XMC4XXX PWM Capture Compare Unit 4 (CCU4) module

  The are four CCU4 modules with dts node labels:
  pwm_ccu40, pwm_ccu41, pwm_ccu42, pwm_ccu43.
  Each module has four slices and each slice has one channel.
  A channel is connected to a particular gpio pin, which are defined
  using pinctrl in:
  dts/arm/infineon/xmc4xxx_xxx-pinctrl.dtsi

  The CCU4 modules uses the CCU clock source. Each slice applies a separate
  prescalar which divides the clock.

  Device tree example:
  A node can define a 'pwm' field, usually referenced in a 'pwms'
  property, where the entries include the PWM module phandle,
  channel number, pulse period (in nanoseconds or set using
  PWM_XX() macros), and a channela
  flag (PWM_POLARITY_NORMAL/PWM_POLARITY_INVERTED).

  The pwm ccu4 node must define the slice-prescaler values and the pinctrl nodes:
  &pwm_ccu40 {
      slice-prescaler = <15 15 15 15>;
      pinctrl-0 = <&pwm_out_p1_1_ccu40_ch2>;
      pinctrl-names = "default";
  };

  Another node can reference the PWM as follows:
  &test_node {
     ...
     pwms = <&pwm_ccu40 0 PWM_SEC(1) PWM_POLARITY_NORMAL>;
     ...
  };

  The user must also explicitly set pinctrl properties.
  The pin should be configured with drive-push-pull bool option and hwctrl should be set
  to disabled. The drive-strength field can be set to any of the supported values:
  &pwm_out_p1_1_ccu40_ch2 {
      drive-strength = "strong-medium-edge";
      drive-push-pull;
      hwctrl = "disabled";
  };

  The CCU4 pinctrl nodes have a node labels in the format
  pwm_out_p{PORT}_{PIN}_ccu4{MODULE_IDX}_ch{CHANNEL_IDX}, where MODULE_IDX and
  CHANNEL_IDX refers to specific pwm_ccu4x module and channel, respectively.
  PORT/PIN pair defines what gpio the channel connects to.

compatible: "infineon,xmc4xxx-ccu4-pwm"

include:
  - name: base.yaml
  - name: pwm-controller.yaml
  - name: pinctrl-device.yaml

properties:
  reg:
    required: true

  pinctrl-0:
    required: true

  pinctrl-names:
    required: true

  slice-prescaler:
    type: array
    required: true
    description: |
      Defines the clock divider for each channel.
      The entry in the array will divide CCU clock by (2 << value).
      The range for the prescaler values is [0, 15].
      Reducing prescaler value will improve resolution but decrease the maximum period.

  "#pwm-cells":
    const: 3

pwm-cells:
  - channel
  - period
  - flags