[U-Boot] [PATCH 5/7] dm: gpio: Add draft GPIO core and convert sandbox to use it

[Pavel Herrmann <morpheus.ibis@gmail.com>]

Hi

On Tuesday 21 August 2012 18:00:51 Marek Vasut wrote:
...snip...
> +/**
> + * gpio_request() - [COMPAT] Request GPIO
> + * gpio:	GPIO number
> + * label:	Name for the requested GPIO
> + *
> + * This function implements the API that's compatible with current
> + * GPIO API used in U-Boot. The request is forwarded to particular
> + * GPIO driver. Returns 0 on success, negative value on error.
> + */
> +int gpio_request(unsigned gpio, const char *label)
> +{
> +	struct gpio_core_entry *e = gpio_to_entry(gpio);
> +	if (!e)
> +		return -EINVAL;
> +
> +	return e->ops->gpio_request(gpio, label);
> +}
...snip...


Your core should have a driver API (as described in the core document), which 
should be in form of gpio_$fname for each $fname in the gpio_ops. on top of 
those you can have the command API, which accesses the gpio pins in a linear 
fashion (like what you have now)

the reason for this is if you have a device on gpio (say some LEDs), which 
knows (from platform data) that pins 3-6 of the parent device are connected to 
this device. in your API, this has no way of working - even if you put global 
pin numbering in the platform data, this would stop working if you had a PnP 
GPIO controllers (say USB).

regards
Pavel Herrmann