Re: [PATCH v5] i2c-gpio: add devicetree support

[Thomas Chou]

Hi Ben,

On 02/23/2011 09:12 AM, Ben Dooks wrote:
> On Mon, Feb 14, 2011 at 10:30:10AM +0800, Thomas Chou wrote:
> > From: Albert Herranz<albert_herranz@xxxxxxxx>
> >
> > This patch adds devicetree support to i2c-gpio driver. The allocation
> > of local data is integrated to a private structure, and use devm_*
> > helper for easy cleanup.
> >
> > It is base on an earlier patch for gc-linux from
> > Albert Herranz<albert_herranz@xxxxxxxx>.
> >
> > Signed-off-by: Thomas Chou<thomas@xxxxxxxxxxxxx>
> > CC: Albert Herranz<albert_herranz@xxxxxxxx>
> > Acked-by: Haavard Skinnemoen<hskinnemoen@xxxxxxxxx>
> > ---
> > for v2.6.39
> > v2 move of nodes probing to a hook, which will be optimized out
> >       when devicetree is not used.
> >     use linux/gpio.h.
> >     move binding doc to i2c/i2c-gpio.txt.
> > v3 use speed-hz instead of udelay in dts binding.
> >     condition the devicetree probe.
> > v4 simplify private allocation.
> > v5 condition module device table export for of.

> > +/* Check if devicetree nodes exist and build platform data */
> > +static int i2c_gpio_of_probe(struct platform_device *pdev,
> > +			     struct i2c_gpio_platform_data *pdata)
> > +{
> > +	struct device_node *np = pdev->dev.of_node;
> > +	const __be32 *prop;
> > +	int sda_pin, scl_pin;
> > +	int len;
> > +
> > +	if (!np || of_gpio_count(np)<  2)
> > +		return -ENXIO;
>
> Would prefer to see different return code, most bus probe functions
> tend to drop these without signalling to the user as they assume the
> device was either never there or totally faulty.
>
> > +	sda_pin = of_get_gpio_flags(np, 0, NULL);
> > +	scl_pin = of_get_gpio_flags(np, 1, NULL);
> > +	if (sda_pin<  0 || scl_pin<  0) {
> > +		pr_err("%s: invalid GPIO pins, sda=%d/scl=%d\n",
> > +		       np->full_name, sda_pin, scl_pin);
> > +		return -ENXIO;
> > +	}
>
> see same as above.
>
> > +	pdata->sda_pin = sda_pin;
> > +	pdata->scl_pin = scl_pin;
> > +	prop = of_get_property(np, "sda-is-open-drain", NULL);
> > +	if (prop)
> > +		pdata->sda_is_open_drain = 1;
> > +	prop = of_get_property(np, "scl-is-open-drain", NULL);
> > +	if (prop)
> > +		pdata->scl_is_open_drain = 1;
> > +	prop = of_get_property(np, "scl-is-output-only", NULL);
> > +	if (prop)
> > +		pdata->scl_is_output_only = 1;
> > +	prop = of_get_property(np, "speed-hz",&len);
> > +	if (prop&&  len>= sizeof(__be32))
> > +		pdata->udelay = DIV_ROUND_UP(1000000, be32_to_cpup(prop) * 2);
> > +	prop = of_get_property(np, "timeout",&len);
> > +	if (prop&&  len>= sizeof(__be32))
> > +		pdata->timeout = msecs_to_jiffies(be32_to_cpup(prop));
> > +
> > +	return 0;
> > +}
> > +#else
> > +static int i2c_gpio_of_probe(struct platform_device *pdev,
> > +			     struct i2c_gpio_platform_data *pdata)
> > +{
> > +	return -ENXIO;
> > +}
>
> might be valid here, however can we make this NULL if no support?

Thanks. How about return NULL if no support, and return pdata if support?

- Thomas
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