ha-core/homeassistant/components/hdmi_cec/services.yaml

power_on:
select_device:
  fields:
    device:
      required: true
      example: '"switch.hdmi_1" or "1.1.0.0" or "01:10"'
      selector:
        text:
send_command:
  fields:
    att:
      example: [0, 2]
      selector:
        object:
    cmd:
      example: 144 or "0x90"
      selector:
        text:
    dst:
      example: 5 or "0x5"
      selector:
        text:
    raw:
      example: '"10:36"'
      selector:
        text:
    src:
      example: 12 or "0xc"
      selector:
        text:
standby:
update:
volume:
  fields:
    down:
      selector:
        number:
          min: 1
          max: 100
    mute:
      selector:
        select:
          options:
            - "off"
            - "on"
            - "toggle"
    up:
      selector:
        number:
          min: 1
          max: 100