Re: [PATCH v2 3/5] misc: eeprom_93xx46: Implement eeprom_93xx46 DT bindings.

[Andrew F. Davis]

On 11/18/2015 11:50 PM, Vladimir Zapolskiy wrote:
> 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@xxxxxxxxxxxxxxxxx>
> > ---
> >   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.

It is referenced in the function below.

> Also you can avoid #ifdef here, if you write
>
>     .of_match_table = of_match_ptr(eeprom_93xx46_of_table)

I think this is backwards, when eeprom_93xx46_of_table is #ifdef'd
off you need to use of_match_ptr so when CONFIG_OF is not defined
you wont get an undefined reference to eeprom_93xx46_of_table.

Without the #ifdef, eeprom_93xx46_of_table will always be defined
and you can just .of_match_table = eeprom_93xx46_of_table; safely.

> 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.

Usually to avoid a lot of dead code and data when OF is not enabled.

> 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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