linux-kernel - Re: [PATCH] dt-bindings: nvmem: nxp,lpc1850-otp: convert to DT schema

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Message-ID: <0ff7932a-c210-4d7a-9405-a77db0f349e7@mleia.com>
Date: Mon, 26 Jan 2026 15:28:53 +0200
From: Vladimir Zapolskiy <vz@...ia.com>
To: Akhila YS <akhilayalmati@...il.com>,
 Srinivas Kandagatla <srini@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dt-bindings: nvmem: nxp,lpc1850-otp: convert to DT schema

Hello Akhila.

On 1/23/26 17:19, Akhila YS wrote:
> Convert NXP LPC18xx OTP memory controller binding to YAML format.
> 
> Signed-off-by: Akhila YS <akhilayalmati@...il.com>
> ---
>   .../devicetree/bindings/nvmem/lpc1850-otp.txt      | 20 ---------
>   .../devicetree/bindings/nvmem/nxp,lpc1850-otp.yaml | 51 ++++++++++++++++++++++
>   2 files changed, 51 insertions(+), 20 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/nvmem/lpc1850-otp.txt b/Documentation/devicetree/bindings/nvmem/lpc1850-otp.txt
> deleted file mode 100644
> index 853b6a754644..000000000000
> --- a/Documentation/devicetree/bindings/nvmem/lpc1850-otp.txt
> +++ /dev/null
> @@ -1,20 +0,0 @@
> -* NXP LPC18xx OTP memory
> -
> -Internal OTP (One Time Programmable) memory for NXP LPC18xx/43xx devices.
> -
> -Required properties:
> -  - compatible: Should be "nxp,lpc1850-otp"
> -  - reg: Must contain an entry with the physical base address and length
> -    for each entry in reg-names.
> -  - address-cells: must be set to 1.
> -  - size-cells: must be set to 1.
> -
> -See nvmem.txt for more information.
> -
> -Example:
> -  otp: otp@...45000 {
> -    compatible = "nxp,lpc1850-otp";
> -    reg = <0x40045000 0x1000>;
> -    #address-cells = <1>;
> -    #size-cells = <1>;
> -  };
> diff --git a/Documentation/devicetree/bindings/nvmem/nxp,lpc1850-otp.yaml b/Documentation/devicetree/bindings/nvmem/nxp,lpc1850-otp.yaml
> new file mode 100644
> index 000000000000..d37e928e7a35
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/nvmem/nxp,lpc1850-otp.yaml
> @@ -0,0 +1,51 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/nvmem/nxp,lpc1850-otp.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: NXP LPC18xx / LPC43xx One-Time Programmable (OTP) memory
> +
> +maintainers:
> +  - Srinivas Kandagatla <srini@...nel.org>

You may add me as a maintainer, the change is not catched by the "lpc18xx"
file name pattern from a record in the MAINTAINERS file, but essentially
it's an NXP LPC18xx/LPC43xx related change.

> +
> +description:
> +  The internal OTP memory in NXP LPC18xx and LPC43xx microcontrollers
> +  provides a dedicated non-volatile storage area designed for permanent,
> +  one-time configuration and data storage.The OTP controller manages write

Please remove all info after the first sentence.

> +  protection, programming sequencing, and error detection mechanisms to
> +  guarantee reliable and safe permanent programming under software control.

What is the source of the information above? I don't quite understand what
is "error detection mechanisms" here etc. OTP controller functions are
defined in SoC ROM, and it is unrelated to the described OTP memory region.

> +
> +allOf:
> +  - $ref: nvmem.yaml#
> +
> +properties:
> +  compatible:
> +    const: nxp,lpc1850-otp
> +
> +  reg:
> +    maxItems: 1
> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 1

This comes from nvmem.yaml

> +
> +required:
> +  - compatible
> +  - reg
> +  - "#address-cells"
> +  - "#size-cells"

Please drop #address-cells/#size-cells from the list of the required
properties.

So far there is no user of this device tree node, and "nvmem-layout"
mechanism may be preferred in future.

> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    otp@...45000 {
> +        compatible = "nxp,lpc1850-otp";
> +        reg = <0x40045000 0x1000>;
> +        #address-cells = <1>;
> +        #size-cells = <1>;
> +    };
> +...
> 

-- 
Best wishes,
Vladimir