linux-kernel - Re: [PATCH v6 2/2] dt-bindings: power: supply: add support for MAX77759 fuel gauge

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Message-ID: <20250915-presoak-answering-2df6fca532ad@spud>
Date: Mon, 15 Sep 2025 18:31:11 +0100
From: Conor Dooley <conor@...nel.org>
To: t.antoine@...ouvain.be
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Sebastian Reichel <sre@...nel.org>,
	Peter Griffin <peter.griffin@...aro.org>,
	André Draszik <andre.draszik@...aro.org>,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v6 2/2] dt-bindings: power: supply: add support for
 MAX77759 fuel gauge

On Mon, Sep 15, 2025 at 12:14:11PM +0200, Thomas Antoine via B4 Relay wrote:
> From: Thomas Antoine <t.antoine@...ouvain.be>
> 
> The Maxim MAX77759 is a companion PMIC for USB Type-C. It contains
> Battery Charger, Fuel Gauge, temperature sensors, USB Type-C Port
> Controller (TCPC), NVMEM, and additional GPIO interfaces
> 
> Use max77759-fg compatible to avoid conflict with drivers for other
> functions.
> 
> The battery node is used to pass the REPCAP and ICHGTERM values
> needed for the initialization of the fuel gauge.
> 
> The nvmem cells are used to get initialization values and to backup
> the learning and the number of cycles. It should work out of the box
> with gs101-oriole and gs101-raven which were previously running
> Android.
> 
> Signed-off-by: Thomas Antoine <t.antoine@...ouvain.be>
> ---
>  .../bindings/power/supply/maxim,max77759.yaml      | 78 ++++++++++++++++++++++
>  1 file changed, 78 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/power/supply/maxim,max77759.yaml b/Documentation/devicetree/bindings/power/supply/maxim,max77759.yaml
> new file mode 100644
> index 0000000000000000000000000000000000000000..4d45739fcaf26273ec57b60049d6d0421df38efb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/supply/maxim,max77759.yaml
> @@ -0,0 +1,78 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/power/supply/maxim,max77759.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Maxim Integrated MAX77759 fuel gauge
> +
> +maintainers:
> +  - Thomas Antoine <t.antoine@...ouvain.be>
> +
> +allOf:
> +  - $ref: power-supply.yaml#
> +
> +properties:
> +  compatible:
> +    const: maxim,max77759-fg

Compatible doesn't match the filename, why?
I assume the "fg" is fuel-gauge, but can this device be anything else?

> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  shunt-resistor-micro-ohms:
> +    description: The value of the current sense resistor in microohms.
> +
> +  monitored-battery:
> +    description: |
> +      The fuel gauge needs the following battery properties:
> +      - charge-full-design-microamp-hours
> +      - charge-term-current-microamp
> +
> +  nvmem-cells:
> +    maxItems: 1
> +    description: |
> +      Saved fuel gauge state. This state will be used during the initialization
> +      and saved on exit. It must be initialized beforehand.
> +      Its layout must be composed of
> +        - RCOMP0 (characterization of the open-circuit voltage)
> +        - TCOMPO (temperature compensation information)
> +        - FULLCAPREP (reported full capacity)
> +        - QRTABLE00, QRTABLE10, QRTABLE20, QRTABLE30 (cell capacity information)
> +        - cv_mixcap (remaining capacity of the cell without empty compensation)
> +        - cv_halftime (time-to-full characterization time constant)
> +      They must all be aligned on 2 bytes. A valid CRC8 checksum must
> +      also be found at the end (polynomial x^8 + x^2 + x + 1).
> +
> +  nvmem-cell-names:
> +    const: fg_state
> +
> +required:
> +  - compatible
> +  - reg
> +  - shunt-resistor-micro-ohms
> +  - monitored-battery
> +  - nvmem-cells
> +  - nvmem-cell-names
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +    i2c {
> +      #address-cells = <1>;
> +      #size-cells = <0>;
> +
> +      fuel-gauge@36 {
> +        compatible = "maxim,max77759-fg";
> +        reg = <0x36>;
> +        interrupts-extended = <&gpa9 3 IRQ_TYPE_LEVEL_LOW>;
> +        shunt-resistor-micro-ohms = <5000>;
> +        monitored-battery = <&battery>;
> +        nvmem-cells = <&fg_state>;
> +        nvmem-cell-names = "fg_state";
> +      };
> +    };
> 
> -- 
> 2.51.0
> 
> 

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