linux-kernel - Re: [PATCH v2 3/5] misc: eeprom_93xx46: Implement eeprom

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Date:	Thu, 19 Nov 2015 07:50:37 +0200
From:	Vladimir Zapolskiy <vz@...ia.com>
To:	Cory Tusar <cory.tusar@...1solutions.com>, robh+dt@...nel.org,
	pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org, agust@...x.de,
	gregkh@...uxfoundation.org
CC:	jic23@...nel.org, broonie@...nel.org, afd@...com, andrew@...n.ch,
	Chris.Healy@....aero, Keith.Vennel@....aero,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/5] misc: eeprom_93xx46: Implement eeprom_93xx46 DT
 bindings.

Hi Cory,

On 19.11.2015 05:29, Cory Tusar wrote:
> This commit implements bindings in the eeprom_93xx46 driver allowing
> device word size and read-only attributes to be specified via
> devicetree.
> 
> Signed-off-by: Cory Tusar <cory.tusar@...1solutions.com>
> ---
>  drivers/misc/eeprom/eeprom_93xx46.c | 62 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 62 insertions(+)
> 
> diff --git a/drivers/misc/eeprom/eeprom_93xx46.c b/drivers/misc/eeprom/eeprom_93xx46.c
> index e1bf0a5..1f29d9a 100644
> --- a/drivers/misc/eeprom/eeprom_93xx46.c
> +++ b/drivers/misc/eeprom/eeprom_93xx46.c
> @@ -13,6 +13,8 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
>  #include <linux/slab.h>
>  #include <linux/spi/spi.h>
>  #include <linux/sysfs.h>
> @@ -294,12 +296,71 @@ static ssize_t eeprom_93xx46_store_erase(struct device *dev,
>  }
>  static DEVICE_ATTR(erase, S_IWUSR, NULL, eeprom_93xx46_store_erase);
>  
> +#ifdef CONFIG_OF
> +static const struct of_device_id eeprom_93xx46_of_table[] = {
> +	{ .compatible = "eeprom-93xx46", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, eeprom_93xx46_of_table);
> +

Please move this declaration closer to struct spi_driver
eeprom_93xx46_driver below.

Also you can avoid #ifdef here, if you write

   .of_match_table = of_match_ptr(eeprom_93xx46_of_table)

Whenever possible please avoid #ifdef's in .c files.

> +static int eeprom_93xx46_probe_dt(struct spi_device *spi)
> +{
> +	struct device_node *np = spi->dev.of_node;
> +	struct eeprom_93xx46_platform_data *pd;
> +	u32 tmp;
> +	int ret;
> +
> +	if (!of_match_device(eeprom_93xx46_of_table, &spi->dev))
> +		return 0;
> +
> +	pd = devm_kzalloc(&spi->dev, sizeof(*pd), GFP_KERNEL);
> +	if (!pd)
> +		return -ENOMEM;
> +
> +	ret = of_property_read_u32(np, "data-size", &tmp);
> +	if (ret < 0) {
> +		dev_err(&spi->dev, "data-size property not found\n");
> +		goto error_free;

Because you use devm_* resource allocation in .probe, just return error.

Plus I would suggest to change "data-size" property to an optional one,
here I mean that if it is omitted, then by default consider pd->flags |=
EE_ADDR8.

> +	}
> +
> +	if (tmp == 8) {
> +		pd->flags |= EE_ADDR8;
> +	} else if (tmp == 16) {
> +		pd->flags |= EE_ADDR16;
> +	} else {
> +		dev_err(&spi->dev, "invalid data-size (%d)\n", tmp);
> +		goto error_free;

Same here.

> +	}
> +
> +	if (of_property_read_bool(np, "read-only"))
> +		pd->flags |= EE_READONLY;
> +
> +	spi->dev.platform_data = pd;
> +
> +	return 1;

On success please return 0.

> +error_free:
> +	devm_kfree(&spi->dev, pd);
> +	return ret;
> +}
> +
> +#else
> +static inline int eeprom_93xx46_probe_dt(struct spi_device *spi)
> +{
> +	return 0;
> +}
> +#endif
> +

I actually don't see a point to have #ifdef CONFIG_OF here.

Instead please add a check for !spi->dev.of_node at the beginning of
eeprom_93xx46_probe_dt() or in .probe()

>  static int eeprom_93xx46_probe(struct spi_device *spi)
>  {
>  	struct eeprom_93xx46_platform_data *pd;
>  	struct eeprom_93xx46_dev *edev;
>  	int err;
>  
> +	err = eeprom_93xx46_probe_dt(spi);
> +	if (err < 0)
> +		return err;
> +
>  	pd = spi->dev.platform_data;
>  	if (!pd) {
>  		dev_err(&spi->dev, "missing platform data\n");
> @@ -370,6 +431,7 @@ static int eeprom_93xx46_remove(struct spi_device *spi)
>  static struct spi_driver eeprom_93xx46_driver = {
>  	.driver = {
>  		.name	= "93xx46",
> +		.of_match_table = eeprom_93xx46_of_table,
>  	},
>  	.probe		= eeprom_93xx46_probe,
>  	.remove		= eeprom_93xx46_remove,
> 
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