Re: [PATCH v3 3/3] input: rotary-encoder: add DT bindings

[Daniel Mack <zonque@gmail.com>]

On 31.07.2012 08:12, Dmitry Torokhov wrote:
> Still, I do not line the copying of pdata over, maybe we coudl have
> something like the patch below?

[...]

> diff --git a/drivers/input/misc/rotary_encoder.c b/drivers/input/misc/rotary_encoder.c
> index ea51265..0f9d746 100644
> --- a/drivers/input/misc/rotary_encoder.c
> +++ b/drivers/input/misc/rotary_encoder.c
> @@ -24,6 +24,8 @@
>  #include <linux/gpio.h>
>  #include <linux/rotary_encoder.h>
>  #include <linux/slab.h>
> +#include <linux/of_platform.h>
> +#include <linux/of_gpio.h>
>  
>  #define DRV_NAME "rotary-encoder"
>  
> @@ -140,6 +142,56 @@ static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
>  	return IRQ_HANDLED;
>  }
>  
> +#ifdef CONFIG_OF
> +static struct of_device_id rotary_encoder_of_match[] = {
> +	{ .compatible = "rotary-encoder", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
> +
> +static struct rotary_encoder_platform_data * __devinit
> +rotary_encoder_parse_dt(struct device *dev)
> +{
> +	const struct of_device_id *of_id =
> +				of_match_device(rotary_encoder_of_match, dev);
> +	struct device_node *np = dev->of_node;
> +	struct rotary_encoder_platform_data *pdata;
> +	enum of_gpio_flags flags;
> +
> +	if (!of_id || !np)
> +		return NULL;
> +
> +	pdata = kzalloc(sizeof(struct rotary_encoder_platform_data),
> +			GFP_KERNEL);
> +	if (!pdata)
> +		return ERR_PTR(-ENOMEM);
> +
> +	of_property_read_u32(np, "rotary-encoder,steps", &pdata->steps);
> +	of_property_read_u32(np, "linux,axis", &pdata->axis);
> +
> +	pdata->gpio_a = of_get_gpio_flags(np, 0, &flags);
> +	pdata->inverted_a = flags & OF_GPIO_ACTIVE_LOW;
> +
> +	pdata->gpio_b = of_get_gpio_flags(np, 1, &flags);
> +	pdata->inverted_b = flags & OF_GPIO_ACTIVE_LOW;
> +
> +	pdata->relative_axis = !!of_get_property(np,
> +					"rotary-encoder,relative-axis", NULL);
> +	pdata->rollover = !!of_get_property(np,
> +					"rotary-encoder,rollover", NULL);
> +	pdata->half_period = !!of_get_property(np,
> +					"rotary-encoder,half-period", NULL))

Syntax error.

> +
> +	return pdata;
> +}
> +#else
> +static inline struct rotary_encoder_platform_data *
> +rotary_encoder_parse_dt(struct device *dev)
> +{
> +	return NULL;
> +}
> +#endif
> +
>  static int __devinit rotary_encoder_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -150,14 +202,19 @@ static int __devinit rotary_encoder_probe(struct platform_device *pdev)
>  	int err;
>  
>  	if (!pdata) {
> -		dev_err(&pdev->dev, "missing platform data\n");
> -		return -ENOENT;
> +		pdata = rotary_encoder_parse_dt(dev);
> +		if (IS_ERR(pdata))
> +			return PTR_ERR(pdata);
> +
> +		if (!pdata) {
> +			dev_err(dev, "missing platform data\n");
> +			return -EINVAL;
> +		}

Well, then you would only parse DT parameters in case of no kernel
provided struct. I thought you were up to a solution where board file
data could override just parts of the DT provided information. But I
don't think the latter would be any useful anyway, so I'm happy with
your solution :)


Thanks for your help,
Daniel