xref: /linux/Documentation/devicetree/bindings/clock/arm,syscon-icst.yaml (revision 08d99b2c23dfa84ca5b5e5c194062a0550888b71) 
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,impd-vco1
70      - arm,impd-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
92examples:
93  - |
94    vco1: clock@00 {
95      compatible = "arm,impd1-vco1";
96      #clock-cells = <0>;
97      lock-offset = <0x08>;
98      vco-offset = <0x00>;
99      clocks = <&sysclk>;
100      clock-output-names = "IM-PD1-VCO1";
101    };
102
103...
104