linux-kernel - Re: [PATCH v1 12/12] nvmem: microchip-otpc: Expose UID registers as 2nd nvmem device

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Message-ID: <7938fb2b-77c4-43a8-a2dc-55dda38404b2@tuxon.dev>
Date: Sat, 24 Aug 2024 18:50:42 +0300
From: claudiu beznea <claudiu.beznea@...on.dev>
To: Alexander Dahl <ada@...rsis.com>
Cc: Christian Melki <christian.melki@...ata.com>,
 Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
 "moderated list:MICROCHIP OTPC DRIVER"
 <linux-arm-kernel@...ts.infradead.org>,
 open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 12/12] nvmem: microchip-otpc: Expose UID registers as
 2nd nvmem device



On 21.08.2024 13:59, Alexander Dahl wrote:
> For SAM9X60 the Product UID x Register containing the Unique Product ID
> is part of the OTPC registers.  We have everything at hand here to just
> create a trivial nvmem device for those.

I'm not sure what is the best option to expose this. I let it to NVMEM
maintainers.

> 
> Signed-off-by: Alexander Dahl <ada@...rsis.com>
> ---
>  drivers/nvmem/microchip-otpc.c | 41 +++++++++++++++++++++++++++++++++-
>  1 file changed, 40 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvmem/microchip-otpc.c b/drivers/nvmem/microchip-otpc.c
> index 047ca5ac6407..52af4c137204 100644
> --- a/drivers/nvmem/microchip-otpc.c
> +++ b/drivers/nvmem/microchip-otpc.c
> @@ -45,6 +45,9 @@
>  #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
> +
>  /**
>   * struct mchp_otpc - OTPC private data structure
>   * @base: base address
> @@ -249,6 +252,16 @@ 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);
> +
> +	return 0;
> +}
> +
>  static struct nvmem_config mchp_nvmem_config = {
>  	.name = MCHP_OTPC_NAME,
>  	.type = NVMEM_TYPE_OTP,
> @@ -258,6 +271,15 @@ 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,
> +	.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;
> @@ -303,8 +325,25 @@ 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)) {
> +		dev_err(&pdev->dev,
> +			"Error (%ld) registering OTP as nvmem device\n",
> +			PTR_ERR(nvmem));
> +		return PTR_ERR(nvmem);

return dev_err_probe();

> +	}
>  
> -	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)) {
> +		dev_err(&pdev->dev,
> +			"Error (%ld) registering UIDxR as nvmem device\n",
> +			PTR_ERR(nvmem));
> +		return PTR_ERR(nvmem);

return dev_err_probe();

> +	}
> +
> +	return 0;
>  }
>  
>  static const struct of_device_id __maybe_unused mchp_otpc_ids[] = {