dts/bindings/pwm/infineon,xmc4xxx-ccu8-pwm.yaml

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

description: |
  Infineon XMC4XXX PWM Capture Compare Unit 8 (CCU8) module

  The PWM CCU8 module can automatically generate a high-side
  and a low-side PWM signal, where the two signals are complementary
  to each other.

  The module supports adding a dead time between the high-side and
  low-side PWM signals.

  The dead time ensures that there is a delay before the PWM state
  transitions from 0 to 1, preventing the high-side and low-side
  switches from being on simultaneously.

  There are two CCU8 modules with DTS node labels: pwm_ccu80 and
  pwm_ccu81. Each module has four slices, and each slice has
  two channels. A channel consists of a corresponding high-side
  and low-side PWM signal.

  The CCU8 modules use the CCU clock source. Each slice applies
  a separate prescaler to divide the clock. The clock divider is
  defined by the 'slice-prescaler' property. Additionally, each
  slice has a dead time prescaler, which divides the slice clock
  for the dead time counter.

  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 channel
  flag (PWM_POLARITY_NORMAL/PWM_POLARITY_INVERTED).

  The 'pwm_ccu8' node must define the following fields:
  &pwm_ccu80 {
          slice-prescaler = <15 15 15 15>;
          slice-deadtime-prescaler = <3 3 3 3>;
          channel-deadtime-high = <0 0 0 0 PWM_MSEC(100) 0 0 0>;
          channel-deadtime-low = <0 0 0 0 PWM_MSEC(100) 0 0 0>;
          pinctrl-0 = <&pwm_out_p5_9_ccu80_ch4_high &pwm_out_p0_0_ccu80_ch4_low>;
          pinctrl-names = "default";
  };

  This will configure channel 4 with a 100msec deadtime on the high
  and low side PWM signals.

  Another node can reference the PWM as follows:
  &test_node {
     ...
     pwms = <&pwm_ccu80 0 PWM_SEC(1) PWM_POLARITY_NORMAL>;
     ...
  };

  The 'pwm_out_p{PORT}_{PIN}_ccu8{MODULE_IDX}_ch{CHANNEL_IDX}_{HIGH_LOW}'
  format is used for CCU8 pinctrl nodes. 'MODULE_IDX' and 'CHANNEL_IDX'
  refer to a specific 'pwm_ccu8x' module and channel, respectively.
  'PORT/PIN' defines the GPIO that the channel connects to.
  'HIGH_LOW' indicates whether the pin is for the high or low-side signal.

  It's not necessary to specify both the high and low pinctrls. Only the low-side
  signal can, for example, be used as PWM, but note that the duty cycle of the
  low signal will be (1 - duty) as set via the API.

  Note that a slice has two channels. Channels 0/1 are in slice 0,
  channels 2/3 are in slice 1, and so on. Each channel can have its own
  duty cycle and high/low dead times. But the pulse duration applies to
  both channels. Thus, when using the PWM control api to modify the pulse width
  on a channel 0, it will also be updated for channel 1 since they are
  in the same slice.

compatible: "infineon,xmc4xxx-ccu8-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 slice.
      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.

  slice-deadtime-prescaler:
    type: array
    required: true
    description: |
      Defines the clock divider for dead time counter for each slice.
      The range for the values is [0, 3].
      Reducing prescaler value will improve dead time resolution but decrease the
      maximum dead time.

  channel-deadtime-high:
    type: array
    required: true
    description: |
      Defines the dead time in nanoseconds for the high-side PWM signal for each channel.

  channel-deadtime-low:
    type: array
    required: true
    description: |
      Defines the dead time in nanoseconds for the low-side PWM signal for each channel.

  "#pwm-cells":
    const: 3

pwm-cells:
  - channel
  - period
  - flags