linux-kernel - Re: [PATCH v7 2/6] dt-bindings: thermal: Add binding document for LVTS thermal controllers

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Message-ID: <76367ac4-15ad-553e-9c88-6464622f393f@collabora.com>
Date:   Thu, 26 May 2022 14:58:06 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Alexandre Bailon <abailon@...libre.com>, rafael@...nel.org,
        rui.zhang@...el.com, daniel.lezcano@...aro.org, amitk@...nel.org
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        khilman@...libre.com, mka@...omium.org, robh+dt@...nel.org,
        krzk+dt@...nel.org, matthias.bgg@...il.com, p.zabel@...gutronix.de,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, james.lo@...iatek.com,
        fan.chen@...iatek.com, louis.yu@...iatek.com,
        rex-bc.chen@...iatek.com
Subject: Re: [PATCH v7 2/6] dt-bindings: thermal: Add binding document for
 LVTS thermal controllers

Il 24/05/22 17:25, Alexandre Bailon ha scritto:
> This patch adds binding document for mt8192 and mt8195 thermal
> controllers.
> 
> Signed-off-by: Alexandre Bailon <abailon@...libre.com>
> ---
>   .../thermal/mediatek,mt8192-lvts.yaml         | 81 +++++++++++++++++++
>   1 file changed, 81 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/thermal/mediatek,mt8192-lvts.yaml
> 
> diff --git a/Documentation/devicetree/bindings/thermal/mediatek,mt8192-lvts.yaml b/Documentation/devicetree/bindings/thermal/mediatek,mt8192-lvts.yaml
> new file mode 100644
> index 000000000000..914c877d1f2f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/thermal/mediatek,mt8192-lvts.yaml
> @@ -0,0 +1,81 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/thermal/mediatek,mt8192-lvts.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: MediaTek SoC LVTS thermal controller
> +
> +maintainers:
> +  - Yu-Chia Chang <ethan.chang@...iatek.com>
> +  - Ben Tseng <ben.tseng@...iatek.com>
> +
> +allOf:
> +  - $ref: thermal-sensor.yaml#
> +  - $ref: /nvmem/nvmem-consumer.yaml#
> +
> +properties:
> +  compatible:
> +    enum:
> +      - mediatek,mt8192-lvts
> +      - mediatek,mt8195-lvts
> +
> +  reg:
> +    minItems: 2
> +    maxItems: 4
> +
> +  interrupts:
> +    maxItems: 2
> +
> +  clocks:
> +    maxItems: 1
> +
> +  "#thermal-sensor-cells":
> +    const: 1
> +
> +  nvmem-cells:
> +    maxItems: 2
> +    description: Calibration data for thermal sensors
> +
> +  nvmem-cell-names:
> +    items:
> +      - const: e_data1
> +      - const: e_data2

 From what I understand, each nvmem cell has calibration data for each thermal
sensor, so let's use some more descriptive names...
some ideas: "lvts1-calib" "lvts1-cal" "calib1".

Also, I think that the best option is to register one driver instance for each
hardware instance, meaning that you should have only one reg, only one nvmem-cell,
only one reset, only one interrupt. This makes it possible to have as many
LVTS instances as possible without any code adjustments in the future.

An example for MT8195:

thermal-sensor@...0b000 {
	compatible = "mediatek,mt8195-lvts";
	reg = <0 0x1100b000 0 0x1000>;
	interrupts = <GIC_SPI 169 IRQ_TYPE_LEVEL_HIGH 0>;
	#thermal-sensor-cells = <1>;
	clocks = <&infracfg_ao CLK_INFRA_AO_THERM>;
	nvmem-cells = <&lvts_e_data1>;
	nvmem-cell-names = "calibration";

	/* is this a reset for lvts1? */
	resets = <&infracfg_ao MT8195_INFRA_RST0_THERM_CTRL_SWRST>;
};

thermal-sensor@...78000 {
	compatible = "mediatek,mt8195-lvts";
	reg = <0 0x11278000 0 0x1000>;
	interrupts = <GIC_SPI 170 IRQ_TYPE_LEVEL_HIGH 0>;
	#thermal-sensor-cells = <1>;
	clocks = <&infracfg_ao CLK_INFRA_AO_THERM>;
	nvmem-cells = <&lvts_e_data2>;
	nvmem-cell-names = "calibration";

	/* is this a reset for lvts2? */
	resets = <&infracfg_ao MT8195_INFRA_RST4_THERM_CTRL_MCU_SWRST>;
};

In the future, a new MediaTek SoC may simply define more nodes..... :-)

> +
> +  resets:
> +    $ref: /schemas/types.yaml#/definitions/phandle-array
> +
> +
> +required:
> +  - '#thermal-sensor-cells'
> +  - compatible
> +  - reg
> +  - interrupts
> +  - clocks
> +  - nvmem-cells
> +  - nvmem-cell-names
> +  - resets
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/thermal/thermal.h>
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    #include <dt-bindings/clock/mt8195-clk.h>
> +    #include <dt-bindings/reset/mt8195-resets.h>
> +
> +    lvts: lvts@...0b000 {

Please use generic names: this should be thermal-sensor@...0b000

> +        compatible = "mediatek,mt8195-lvts";
> +        #thermal-sensor-cells = <1>;
> +        reg = <0 0x1100b000 0 0x1000>,
> +              <0 0x11278000 0 0x1000>;
> +        interrupts = <GIC_SPI 169 IRQ_TYPE_LEVEL_HIGH 0>,
> +                     <GIC_SPI 170 IRQ_TYPE_LEVEL_HIGH 0>;
> +        clocks = <&infracfg_ao CLK_INFRA_AO_THERM>;
> +        resets = <&infracfg_ao MT8195_INFRA_RST0_THERM_CTRL_SWRST>,
> +                 <&infracfg_ao MT8195_INFRA_RST4_THERM_CTRL_MCU_SWRST>;
> +        nvmem-cells = <&lvts_e_data1 &lvts_e_data2>;
> +        nvmem-cell-names = "e_data1","e_data2";
> +    };
> +...