linux-kernel - Re: [PATCH v11 char-misc-next 2/2] misc: microchip: pci1xxxx: Add support to read and write into PCI1XXXX EEPROM via NVMEM sysfs

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Message-ID: <78faf23f4f746f332dc53f7f981ac0fe@walle.cc>
Date:   Mon, 08 May 2023 08:44:04 +0200
From:   Michael Walle <michael@...le.cc>
To:     "Vaibhaav Ram T.L" <vaibhaavram.tl@...rochip.com>
Cc:     gregkh@...uxfoundation.org, arnd@...db.de,
        kumaravel.thiagarajan@...rochip.com,
        tharunkumar.pasumarthi@...rochip.com, linux-kernel@...r.kernel.org,
        linux-gpio@...r.kernel.org, UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH v11 char-misc-next 2/2] misc: microchip: pci1xxxx: Add
 support to read and write into PCI1XXXX EEPROM via NVMEM sysfs

Hi,

> @@ -219,6 +348,22 @@ static int pci1xxxx_otp_eeprom_probe(struct
> auxiliary_device *aux_dev,
>  		return -ENOMEM;
> 
>  	priv->pdev = aux_dev;
> +	priv->nvmem_config_eeprom.type = NVMEM_TYPE_EEPROM;
> +	priv->nvmem_config_eeprom.name = EEPROM_NAME;
> +	priv->nvmem_config_eeprom.dev = &aux_dev->dev;
> +	priv->nvmem_config_eeprom.owner = THIS_MODULE;
> +	priv->nvmem_config_eeprom.reg_read = pci1xxxx_eeprom_read;
> +	priv->nvmem_config_eeprom.reg_write = pci1xxxx_eeprom_write;
> +	priv->nvmem_config_eeprom.priv = priv;
> +	priv->nvmem_config_eeprom.stride = 1;
> +	priv->nvmem_config_eeprom.word_size = 1;
> +	priv->nvmem_config_eeprom.size = EEPROM_SIZE_BYTES;
> +
> +	priv->nvmem_eeprom = devm_nvmem_register(&aux_dev->dev,
> +						 &priv->nvmem_config_eeprom);
> +	if (!priv->nvmem_eeprom)
> +		return -ENOMEM;
> +
>  	priv->nvmem_config_otp.type = NVMEM_TYPE_OTP;
>  	priv->nvmem_config_otp.name = OTP_NAME;
>  	priv->nvmem_config_otp.dev = &aux_dev->dev;
> @@ -258,6 +403,9 @@ static int pci1xxxx_otp_eeprom_probe(struct
> auxiliary_device *aux_dev,
> 
>  	dev_set_drvdata(&aux_dev->dev, priv);
> 
> +	if (is_eeprom_responsive(priv))
> +		priv->is_eeprom_present = true;

What's this? The eeprom isn't there (or in whatever state), then you
still register the nvmem device, but read and write doesn't do anything
useful. You shouldn't register the device in the first place if it
is not functional.

-michael