Re: [PATCH v2 6/9] nvmem: ocotp: Fix SoC ID reading for i.MX8MP

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hi,

On 11/17/25 9:35 AM, Sascha Hauer wrote:
> On i.MX8MP the SoC ID is stored at 0x420/0x430, not on 0x410/0x420 as on
> other i.MX8M SoCs. Also on i.MX8MP the SoC ID is 128bit and not 64bit
> with the upper bits stored at 0xe00/0xe10.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

As this has implications for user space (e.g. journald quotas are per
directory and machine id changes the dir), this deserves a mention in
the migration guide.

Cheers,
Ahmad

> ---
>  drivers/nvmem/ocotp.c | 33 +++++++++++++++++++++++++++------
>  1 file changed, 27 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/nvmem/ocotp.c b/drivers/nvmem/ocotp.c
> index 7bca27540417ad9ba0ce5c5f8ec43ad1c63638b9..affca938849d0d1a8dc347e3a0e1f3a380f1aab7 100644
> --- a/drivers/nvmem/ocotp.c
> +++ b/drivers/nvmem/ocotp.c
> @@ -853,17 +853,38 @@ static int imx_ocotp_init_dt(struct ocotp_priv *priv)
>  	return imx8m_feat_ctrl_init(priv->dev.parent, tester3, tester4, priv->data->feat);
>  }
>  
> +#define IMX8MP_OCOTP_UID(n)	\
> +	(OCOTP_WORD(0x420 + 0x10 * (n)) | OCOTP_BIT(0) | OCOTP_WIDTH(32))
> +#define IMX8MP_OCOTP_UID_2(n)	\
> +	(OCOTP_WORD(0xe00 + 0x10 * (n)) | OCOTP_BIT(0) | OCOTP_WIDTH(32))
> +
>  static void imx_ocotp_set_unique_machine_id(void)
>  {
> -	uint32_t unique_id_parts[UNIQUE_ID_NUM];
> -	int i;
> +	bool is_imx8mp = of_machine_is_compatible("fsl,imx8mp");
> +	uint32_t uid[4];
> +	int len;
>  
> -	for (i = 0; i < UNIQUE_ID_NUM; i++)
> -		if (imx_ocotp_read_field(OCOTP_UNIQUE_ID(i),
> -					 &unique_id_parts[i]))
> +	if (is_imx8mp) {
> +		if (imx_ocotp_read_field(IMX8MP_OCOTP_UID(0), &uid[0]))
> +			return;
> +		if (imx_ocotp_read_field(IMX8MP_OCOTP_UID(1), &uid[1]))
> +			return;
> +
> +		if (imx_ocotp_read_field(IMX8MP_OCOTP_UID_2(0), &uid[2]))
> +			return;
> +		if (imx_ocotp_read_field(IMX8MP_OCOTP_UID_2(1), &uid[3]))
>  			return;
> +		len = sizeof(uid);
> +	} else {
> +		if (imx_ocotp_read_field(OCOTP_UNIQUE_ID(0), &uid[0]))
> +			return;
> +		if (imx_ocotp_read_field(OCOTP_UNIQUE_ID(1), &uid[1]))
> +			return;
> +
> +		len = sizeof(uid) / 2;
> +	}
>  
> -	machine_id_set_hashable(unique_id_parts, sizeof(unique_id_parts));
> +	machine_id_set_hashable(uid, len);
>  }
>  
>  static int imx_ocotp_probe(struct device *dev)
> 

-- 
Pengutronix e.K.                  |                             |
Steuerwalder Str. 21              | http://www.pengutronix.de/  |
31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |