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