Re: [PATCH 1/6] dt-bindings: clocks: add binding for generic clock-generators
From: Alexander Stein <hidden>
Date: 2024-07-10 07:02:45
Also in:
linux-clk, linux-devicetree, linux-rockchip, lkml
Hello Heiko, Am Dienstag, 9. Juli 2024, 14:31:16 CEST schrieb Heiko Stuebner:
In contrast to fixed clocks that are described as ungateable, boards sometimes use additional clock generators for things like PCIe reference clocks, that need actual supplies to get enabled and enable-gpios to be toggled for them to work.
Fixed clocks are intended to be ungateable? Where does this come from?
quoted hunk ↗ jump to hunk
This adds a binding for such clock generators that are not configurable themself, but need to handle supplies for them to work. While in a lot of cases the type of the IC used is described in board schematics, in some cases just a generic type description like "100MHz, 3.3V" might also be used. The binding therefore allows both cases. Specifying the type is of course preferred. The clock-frequency is set in devicetree, because while some clock generators have pins to decide between multipls output rates, those are generally set statically on the board-layout-level. Signed-off-by: Heiko Stuebner <heiko@sntech.de> --- .../bindings/clock/clock-generator.yaml | 62 +++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 Documentation/devicetree/bindings/clock/clock-generator.yamldiff --git a/Documentation/devicetree/bindings/clock/clock-generator.yaml b/Documentation/devicetree/bindings/clock/clock-generator.yaml new file mode 100644 index 0000000000000..f44e61e414e89 --- /dev/null +++ b/Documentation/devicetree/bindings/clock/clock-generator.yaml@@ -0,0 +1,62 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/clock/clock-generator.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Simple clock generators + +maintainers: + - Heiko Stuebner <heiko@sntech.de> + +properties: + $nodename: + anyOf: + - description: + Preferred name is 'clock-<freq>' with <freq> being the output + frequency as defined in the 'clock-frequency' property. + pattern: "^clock-([0-9]+|[a-z0-9-]+)$" + - description: Any name allowed + deprecated: true + + compatible: + oneOf: + - const: clock-generator + - items: + - enum: + - diodes,pi6c557-03b + - diodes,pi6c557-05b + - const: clock-generator + + "#clock-cells": + const: 0 + + clock-frequency: true + + clock-output-names: + maxItems: 1 + + enable-gpios: + description: + Contains a single GPIO specifier for the GPIO that enables and disables + the clock generator. + maxItems: 1 + + vdd-supply: + description: handle of the regulator that provides the supply voltage
So essentially only enable-gpios and vdd-supply is added in comparison to fixed-clock. Does it make sense to add that to the fixed-clocks instead? Similar to fixed-regulator.
+ +required: + - compatible + - "#clock-cells" + - clock-frequency
With this list it's essentially the same as fixed-clock. Best regards, Alexander
+
+additionalProperties: false
+
+examples:
+ - |
+ clock {
+ compatible = "clock-generator";
+ #clock-cells = <0>;
+ clock-frequency = <1000000000>;
+ };
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