linux-kernel - Re: [PATCHv7 6/7] eeprom: 93xx46: extend driver to plug into the NVMEM framework

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Date:	Thu, 3 Mar 2016 00:08:15 +0200
From:	Vladimir Zapolskiy <vz@...ia.com>
To:	Andrew Lunn <andrew@...n.ch>, GregKH <greg@...ah.com>
Cc:	srinivas.kandagatla@...aro.org, maxime.ripard@...e-electrons.com,
	wsa@...-dreams.de, broonie@...nel.org,
	linux-kernel@...r.kernel.org, pantelis.antoniou@...sulko.com,
	bgolaszewski@...libre.com
Subject: Re: [PATCHv7 6/7] eeprom: 93xx46: extend driver to plug into the
 NVMEM framework

Hi Andrew,

On 26.02.2016 21:59, Andrew Lunn wrote:
> Add a regmap for accessing the EEPROM, and then use that with the
> NVMEM framework. Enable backward compatibility in the NVMEM config
> structure, so that the 'eeprom' file in sys is provided by the
> framework.
> 
> Signed-off-by: Andrew Lunn <andrew@...n.ch>
> Acked-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> ---

[snip]

>  
>  static ssize_t
> -eeprom_93xx46_bin_read(struct file *filp, struct kobject *kobj,
> -		       struct bin_attribute *bin_attr,
> -		       char *buf, loff_t off, size_t count)
> +eeprom_93xx46_read(struct eeprom_93xx46_dev *edev, char *buf,
> +		   unsigned off, size_t count)
>  {
> -	struct eeprom_93xx46_dev *edev;
> -	struct device *dev;
>  	ssize_t ret = 0;
>  
> -	dev = kobj_to_dev(kobj);
> -	edev = dev_get_drvdata(dev);
> +	if (unlikely(off >= edev->size))
> +		return 0;
> +	if ((off + count) > edev->size)
> +		count = edev->size - off;
> +	if (unlikely(!count))
> +		return count;
>  

I'm scratching my head, do you want to kind of revert
the change https://lkml.org/lkml/2015/7/26/89 ? Why?

If you know regmap_config.max_register, then all necessary
boundary checks can be done inside NVMEM core.

>  	mutex_lock(&edev->lock);
>  
> @@ -226,16 +231,17 @@ eeprom_93xx46_write_word(struct eeprom_93xx46_dev *edev,
>  }
>  
>  static ssize_t
> -eeprom_93xx46_bin_write(struct file *filp, struct kobject *kobj,
> -			struct bin_attribute *bin_attr,
> -			char *buf, loff_t off, size_t count)
> +eeprom_93xx46_write(struct eeprom_93xx46_dev *edev, const char *buf,
> +		    loff_t off, size_t count)
>  {
> -	struct eeprom_93xx46_dev *edev;
> -	struct device *dev;
>  	int i, ret, step = 1;
>  
> -	dev = kobj_to_dev(kobj);
> -	edev = dev_get_drvdata(dev);
> +	if (unlikely(off >= edev->size))
> +		return -EFBIG;
> +	if ((off + count) > edev->size)
> +		count = edev->size - off;
> +	if (unlikely(!count))
> +		return count;
>  

See a comment above.

>  	/* only write even number of bytes on 16-bit devices */
>  	if (edev->addrlen == 6) {
> @@ -272,6 +278,49 @@ eeprom_93xx46_bin_write(struct file *filp, struct kobject *kobj,
>  	return ret ? : count;
>  }
>  
> +/*
> + * Provide a regmap interface, which is registered with the NVMEM
> + * framework
> +*/
> +static int eeprom_93xx46_regmap_read(void *context, const void *reg,
> +				     size_t reg_size, void *val,
> +				     size_t val_size)
> +{
> +	struct eeprom_93xx46_dev *eeprom_93xx46 = context;
> +	off_t offset = *(u32 *)reg;
> +	int err;
> +
> +	err = eeprom_93xx46_read(eeprom_93xx46, val, offset, val_size);
> +	if (err)
> +		return err;
> +	return 0;

return eeprom_93xx46_read(eeprom_93xx46, val, offset, val_size);

> +}
> +
> +static int eeprom_93xx46_regmap_write(void *context, const void *data,
> +				      size_t count)
> +{
> +	struct eeprom_93xx46_dev *eeprom_93xx46 = context;
> +	const char *buf;
> +	u32 offset;
> +	size_t len;
> +	int err;
> +
> +	memcpy(&offset, data, sizeof(offset));
> +	buf = (const char *)data + sizeof(offset);
> +	len = count - sizeof(offset);
> +
> +	err = eeprom_93xx46_write(eeprom_93xx46, buf, offset, len);
> +	if (err)
> +		return err;
> +	return 0;

return eeprom_93xx46_write(eeprom_93xx46, buf, offset, len);

> +}
> +


--
With best wishes,
Vladimir