linux-kernel - Re: [PATCH 1/4] regulator: dt-bindings: Add Linear Technology LTM8054 regulator

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Message-ID: <936e16dd-d11f-4452-8942-64366f173d6f@baylibre.com>
Date: Tue, 16 Sep 2025 14:24:42 -0500
From: David Lechner <dlechner@...libre.com>
To: Romain Gantois <romain.gantois@...tlin.com>,
 Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Jonathan Cameron <jic23@...nel.org>,
 Nuno Sá <nuno.sa@...log.com>,
 Andy Shevchenko <andy@...nel.org>
Cc: Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
 linux-iio@...r.kernel.org
Subject: Re: [PATCH 1/4] regulator: dt-bindings: Add Linear Technology LTM8054
 regulator

On 9/16/25 5:24 AM, Romain Gantois wrote:
> The Linear Technology LTM8054 is a Buck-Boost voltage regulator with an
> input range of 5V to 36V and an output range of 1.2V to 36V.
> 
> The LTM8054's output voltage level is typically set using a voltage divider
> between the Vout and FB pins, the FB pin being constantly regulated to
> 1.2V.
> 
> The output current limit of the LTM8054 may be statically set by placing a
> sense resistor on a dedicated pin. This limit can then be lowered by
> controlling the voltage level on the CTL pin.
> 
> Describe the LTM8054 voltage regulator.
> 
> Signed-off-by: Romain Gantois <romain.gantois@...tlin.com>
> ---
>  .../bindings/regulator/lltc,ltm8054.yaml           | 77 ++++++++++++++++++++++
>  MAINTAINERS                                        |  5 ++
>  2 files changed, 82 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/regulator/lltc,ltm8054.yaml b/Documentation/devicetree/bindings/regulator/lltc,ltm8054.yaml
> new file mode 100644
> index 0000000000000000000000000000000000000000..4db11be178b0e662ec51f3d3d73202f8c32625d3
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/regulator/lltc,ltm8054.yaml
> @@ -0,0 +1,77 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/regulator/lltc,ltm8054.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Linear Technology LTM8054 buck-boost regulator
> +
> +maintainers:
> +  - Romain Gantois <romain.gantois@...tlin.com>
> +
> +description:
> +  This regulator operates over an input voltage range of 5V to 36V, and can
> +  output from 1.2V to 36V. The output voltage level is typically set with a
> +  voltage divider between the Vout pin and the FB pin which is internally
> +  regulated to 1.2V.
> +
> +  The output current of the LTM8054 can be limited by tying the Iout pin to a
> +  current sense resistor. This limit can be further lowered by applying a
> +  voltage below 1.2V to the CTL pin.
> +
> +allOf:
> +  - $ref: /schemas/regulator/regulator.yaml#
> +
> +properties:
> +  compatible:
> +    const: lltc,ltm8054

Looks like they got bought by Analog Devices Inc., so adi,ltm8054.

> +
> +  enable-gpios:
> +    description: GPIO connected to the RUN pin.
> +    maxItems: 1
> +
> +  lltc,fb-voltage-divider:
> +    description:
> +      An array of two integers containing the resistor values
> +      R1 and R2 of the feedback voltage divider in Ohms.
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    minItems: 2
> +    maxItems: 2
> +
> +  lltc,iout-rsense-micro-ohms:
> +    description:
> +      Value of the output current sense resistor, in micro Ohms.
> +
> +  io-channels:
> +    items:
> +      - description: DAC controlling the voltage level of the CTL pin.
> +
> +  io-channel-names:
> +    items:
> +      - const: ctl
> +
> +required:
> +  - compatible
> +  - lltc,fb-voltage-divider
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    / {

Examples usually don't have a root node. Probably explains
the bot errors. (but you should have seen the same errors
locally with make dt_binding_check.)

> +
> +        regulator {
> +            compatible = "lltc,ltm8054";
> +
> +            enable-gpios = <&gpio0 1 GPIO_ACTIVE_HIGH>;
> +
> +            lltc,fb-voltage-divider = <1000000 68000>;
> +
> +            lltc,iout-rsense-micro-ohms = <20000>;
> +
> +            io-channels = <&dac 1>;
> +            io-channel-names = "ctl";
> +        };
> +    };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index fe168477caa45799dfe07de2f54de6d6a1ce0615..7160179e6bf9d45a241582c1b6df8c0ebf6c3641 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -14517,6 +14517,11 @@ W:	https://ez.analog.com/linux-software-drivers
>  F:	Documentation/devicetree/bindings/i2c/i2c-mux-ltc4306.txt
>  F:	drivers/i2c/muxes/i2c-mux-ltc4306.c
>  
> +LTM8054 REGULATOR DRIVER
> +M:	Romain Gantois <romain.gantois@...tlin.com>
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/regulator/lltc,ltm8054.yaml
> +
>  LTP (Linux Test Project)
>  M:	Andrea Cervesato <andrea.cervesato@...e.com>
>  M:	Cyril Hrubis <chrubis@...e.cz>
>