linux-kernel - Re: [PATCH v3 14/19] nvmem: microchip-otpc: Expose UID registers as 2nd nvmem device

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <05128a16-553d-49d5-b09d-2c3e03cb4421@tuxon.dev>
Date: Sat, 31 Jan 2026 18:11:56 +0200
From: Claudiu Beznea <claudiu.beznea@...on.dev>
To: Alexander Dahl <ada@...rsis.com>
Cc: Nicolas Ferre <nicolas.ferre@...rochip.com>,
 Alexandre Belloni <alexandre.belloni@...tlin.com>,
 Ryan Wanner <ryan.wanner@...rochip.com>,
 linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
 Srinivas Kandagatla <srini@...nel.org>
Subject: Re: [PATCH v3 14/19] nvmem: microchip-otpc: Expose UID registers as
 2nd nvmem device



On 1/20/26 17:44, Alexander Dahl wrote:
> For SAM9X60 the Product UID x Register containing the Unique Product ID
> is part of the OTPC registers. 

SAMA7G5 as well.

> We have everything at hand here to just
> create a trivial nvmem device for those.

Please massage a bit the patch description to match 
https://www.kernel.org/doc/html/v6.13/process/submitting-patches.html#describe-your-changes

> 
> Signed-off-by: Alexander Dahl <ada@...rsis.com>
> ---
> 
> Notes:
>      v3:
>      - no changes
>      
>      v2:
>      - Use dev_err_probe() for error reporting (thanks Claudiu)
>      - Move required register definition over here from removed patch
> 
>   drivers/nvmem/microchip-otpc.c | 38 +++++++++++++++++++++++++++++++++-
>   1 file changed, 37 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvmem/microchip-otpc.c b/drivers/nvmem/microchip-otpc.c
> index 34c0d7611f3e4..b35ed13b004bb 100644
> --- a/drivers/nvmem/microchip-otpc.c
> +++ b/drivers/nvmem/microchip-otpc.c
> @@ -25,10 +25,14 @@
>   #define MCHP_OTPC_HR			(0x20)
>   #define MCHP_OTPC_HR_SIZE		GENMASK(15, 8)
>   #define MCHP_OTPC_DR			(0x24)
> +#define MCHP_OTPC_UID0R			(0x60)
>   
>   #define MCHP_OTPC_NAME			"mchp-otpc"
>   #define MCHP_OTPC_SIZE			(11 * 1024)
>   
> +#define MCHP_OTPC_UID_NAME		"mchp-uid"
> +#define MCHP_OTPC_UID_SIZE		16

I think you can drop these as they are used (individually) in a single place.

> +
>   /**
>    * struct mchp_otpc - OTPC private data structure
>    * @base: base address
> @@ -230,6 +234,16 @@ static int mchp_otpc_init_packets_list(struct mchp_otpc *otpc, u32 *size)
>   	return 0;
>   }
>   
> +static int mchp_otpc_uid_read(void *priv, unsigned int offset,
> +			      void *val, size_t bytes)
> +{
> +	struct mchp_otpc *otpc = priv;
> +
> +	memcpy_fromio(val, otpc->base + MCHP_OTPC_UID0R + offset, bytes);

Include <asm-generic/logic_io.h> for this one?

> +
> +	return 0;
> +}
> +
>   static struct nvmem_config mchp_nvmem_config = {
>   	.name = MCHP_OTPC_NAME,
>   	.type = NVMEM_TYPE_OTP,
> @@ -239,6 +253,15 @@ static struct nvmem_config mchp_nvmem_config = {
>   	.reg_read = mchp_otpc_read,
>   };
>   
> +static struct nvmem_config mchp_otpc_uid_nvmem_config = {
> +	.name = MCHP_OTPC_UID_NAME,

Should the type be filled here?


> +	.read_only = true,
> +	.word_size = 4,
> +	.stride = 4,
> +	.size = MCHP_OTPC_UID_SIZE,
> +	.reg_read = mchp_otpc_uid_read,
> +};
> +
>   static int mchp_otpc_probe(struct platform_device *pdev)
>   {
>   	struct nvmem_device *nvmem;
> @@ -269,8 +292,21 @@ static int mchp_otpc_probe(struct platform_device *pdev)
>   	mchp_nvmem_config.size = size;
>   	mchp_nvmem_config.priv = otpc;
>   	nvmem = devm_nvmem_register(&pdev->dev, &mchp_nvmem_config);
> +	if (IS_ERR(nvmem)) {
> +		return dev_err_probe(&pdev->dev, PTR_ERR(nvmem),
> +				     "Error registering OTP as nvmem device\n");
> +	}
>   
> -	return PTR_ERR_OR_ZERO(nvmem);
> +	mchp_otpc_uid_nvmem_config.dev = otpc->dev;
> +	mchp_otpc_uid_nvmem_config.priv = otpc;
> +
> +	nvmem = devm_nvmem_register(&pdev->dev, &mchp_otpc_uid_nvmem_config);
> +	if (IS_ERR(nvmem)) {
> +		return dev_err_probe(&pdev->dev, PTR_ERR(nvmem),
> +				     "Error registering UIDxR as nvmem device\n");
> +	}
> +
> +	return 0;
>   }
>   
>   static const struct of_device_id __maybe_unused mchp_otpc_ids[] = {