1 # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
4 $id: http://devicetree.org/schemas/clock/arm,syscon-icst.yaml#
5 $schema: http://devicetree.org/meta-schemas/core.yaml#
7 title: ARM System Controller ICST Clocks
10 - Linus Walleij <linusw@kernel.org>
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.
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.
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).
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.
35 Hardware variant RDW OD VDW
37 Integrator/AP 22 1 Bit 8 0, rest variable
40 Integrator/AP 46 3 Bit 8 0, rest variable
43 Integrator/AP 22 or 1 17 or (33 or 25 MHz)
44 integratorap-pci 14 1 14
46 Integrator/CP 22 variable Bit 8 0, rest variable
49 Integrator/CP 22 variable Bit 8 0, rest variable
52 The ICST oscillator must be provided inside a system controller node.
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
74 description: The VCO register
77 description: Parent clock for the ICST VCO
84 $ref: /schemas/types.yaml#/definitions/uint32
85 description: Offset to the unlocking register for the oscillator
88 $ref: /schemas/types.yaml#/definitions/uint32
89 description: Offset to the VCO register for the oscillator
97 additionalProperties: false
102 compatible = "arm,impd1-vco1";
104 lock-offset = <0x08>;
107 clock-output-names = "IM-PD1-VCO1";