1# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) 2%YAML 1.2 3--- 4$id: http://devicetree.org/schemas/clock/arm,syscon-icst.yaml# 5$schema: http://devicetree.org/meta-schemas/core.yaml# 6 7title: ARM System Controller ICST Clocks 8 9maintainers: 10 - Linus Walleij <linusw@kernel.org> 11 12description: | 13 The ICS525 and ICS307 oscillators are produced by Integrated 14 Devices Technology (IDT). ARM integrated these oscillators deeply into their 15 reference designs by adding special control registers that manage such 16 oscillators to their system controllers. 17 18 The various ARM system controllers contain logic to serialize and initialize 19 an ICST clock request after a write to the 32 bit register at an offset 20 into the system controller. Furthermore, to even be able to alter one of 21 these frequencies, the system controller must first be unlocked by 22 writing a special token to another offset in the system controller. 23 24 Some ARM hardware contain special versions of the serial interface that only 25 connects the low 8 bits of the VDW (missing one bit), hard-wires RDW to 26 different values and sometimes also hard-wires the output divider. They 27 therefore have special compatible strings as per this table (the OD value is 28 the value on the pins, not the resulting output divider). 29 30 In the core modules and logic tiles, the ICST is a configurable clock fed 31 from a 24 MHz clock on the motherboard (usually the main crystal) used for 32 generating e.g. video clocks. It is located on the core module and there is 33 only one of these. This clock node must be a subnode of the core module. 34 35 Hardware variant RDW OD VDW 36 37 Integrator/AP 22 1 Bit 8 0, rest variable 38 integratorap-cm 39 40 Integrator/AP 46 3 Bit 8 0, rest variable 41 integratorap-sys 42 43 Integrator/AP 22 or 1 17 or (33 or 25 MHz) 44 integratorap-pci 14 1 14 45 46 Integrator/CP 22 variable Bit 8 0, rest variable 47 integratorcp-cm-core 48 49 Integrator/CP 22 variable Bit 8 0, rest variable 50 integratorcp-cm-mem 51 52 The ICST oscillator must be provided inside a system controller node. 53 54properties: 55 "#clock-cells": 56 const: 0 57 58 compatible: 59 enum: 60 - arm,syscon-icst525 61 - arm,syscon-icst307 62 - arm,syscon-icst525-integratorap-cm 63 - arm,syscon-icst525-integratorap-sys 64 - arm,syscon-icst525-integratorap-pci 65 - arm,syscon-icst525-integratorcp-cm-core 66 - arm,syscon-icst525-integratorcp-cm-mem 67 - arm,integrator-cm-auxosc 68 - arm,versatile-cm-auxosc 69 - arm,impd1-vco1 70 - arm,impd1-vco2 71 72 clocks: 73 description: Parent clock for the ICST VCO 74 maxItems: 1 75 76 clock-output-names: 77 maxItems: 1 78 79 lock-offset: 80 $ref: '/schemas/types.yaml#/definitions/uint32' 81 description: Offset to the unlocking register for the oscillator 82 83 vco-offset: 84 $ref: '/schemas/types.yaml#/definitions/uint32' 85 description: Offset to the VCO register for the oscillator 86 87required: 88 - "#clock-cells" 89 - compatible 90 - clocks 91 92additionalProperties: false 93 94examples: 95 - | 96 vco1: clock { 97 compatible = "arm,impd1-vco1"; 98 #clock-cells = <0>; 99 lock-offset = <0x08>; 100 vco-offset = <0x00>; 101 clocks = <&sysclk>; 102 clock-output-names = "IM-PD1-VCO1"; 103 }; 104 105... 106