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# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/clock/arm,syscon-icst.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: ARM System Controller ICST Clocks
maintainers:
- Linus Walleij <linusw@kernel.org>
description: |
The ICS525 and ICS307 oscillators are produced by Integrated
Devices Technology (IDT). ARM integrated these oscillators deeply into their
reference designs by adding special control registers that manage such
oscillators to their system controllers.
The various ARM system controllers contain logic to serialize and initialize
an ICST clock request after a write to the 32 bit register at an offset
into the system controller. Furthermore, to even be able to alter one of
these frequencies, the system controller must first be unlocked by
writing a special token to another offset in the system controller.
Some ARM hardware contain special versions of the serial interface that only
connects the low 8 bits of the VDW (missing one bit), hard-wires RDW to
different values and sometimes also hard-wires the output divider. They
therefore have special compatible strings as per this table (the OD value is
the value on the pins, not the resulting output divider).
In the core modules and logic tiles, the ICST is a configurable clock fed
from a 24 MHz clock on the motherboard (usually the main crystal) used for
generating e.g. video clocks. It is located on the core module and there is
only one of these. This clock node must be a subnode of the core module.
Hardware variant RDW OD VDW
Integrator/AP 22 1 Bit 8 0, rest variable
integratorap-cm
Integrator/AP 46 3 Bit 8 0, rest variable
integratorap-sys
Integrator/AP 22 or 1 17 or (33 or 25 MHz)
integratorap-pci 14 1 14
Integrator/CP 22 variable Bit 8 0, rest variable
integratorcp-cm-core
Integrator/CP 22 variable Bit 8 0, rest variable
integratorcp-cm-mem
The ICST oscillator must be provided inside a system controller node.
properties:
"#clock-cells":
const: 0
compatible:
enum:
- arm,syscon-icst525
- arm,syscon-icst307
- arm,syscon-icst525-integratorap-cm
- arm,syscon-icst525-integratorap-sys
- arm,syscon-icst525-integratorap-pci
- arm,syscon-icst525-integratorcp-cm-core
- arm,syscon-icst525-integratorcp-cm-mem
- arm,integrator-cm-auxosc
- arm,versatile-cm-auxosc
- arm,impd-vco1
- arm,impd-vco2
clocks:
description: Parent clock for the ICST VCO
maxItems: 1
clock-output-names:
maxItems: 1
lock-offset:
$ref: '/schemas/types.yaml#/definitions/uint32'
description: Offset to the unlocking register for the oscillator
vco-offset:
$ref: '/schemas/types.yaml#/definitions/uint32'
description: Offset to the VCO register for the oscillator
required:
- "#clock-cells"
- compatible
- clocks
additionalProperties: false
examples:
- |
vco1: clock {
compatible = "arm,impd1-vco1";
#clock-cells = <0>;
lock-offset = <0x08>;
vco-offset = <0x00>;
clocks = <&sysclk>;
clock-output-names = "IM-PD1-VCO1";
};
...
|
