[PATCH V2 1/2] RTEMS GPIO API definition and implementation.

[André Marques]

Hello Ketul,

On 13-08-2015 13:04, Ketul Shah wrote:
> Hi Andre,
>
> Great API and happy to know that it is merged with main line.
>
> Eventually I implemented GPIO driver for BBB using this API. After 
> debugging for rtems_gpio_get_value() on BBB I found the following bug.
>
> For BBB, GPIO pin nos. varies from 0 to 32. So function return type 
> would be uint32_t instead of uint8_t.
>
> For BBB I wrote :-
>
> uint32_t rtems_gpio_bsp_get_value(uint32_t bank, uint32_t pin)
> {
>   return (mmio_read(bbb_reg(bank, AM335X_GPIO_DATAIN)) & BIT(pin));
> }
>

the rtems_gpio_bsp_get_value returns the value of a GPIO pin, which can 
only be either 0 or 1. This is not platform dependent. Any value greater 
than zero should map to 1.

I do notice that I forgot this detail in the Pi implementation too, so 
it is also returning a 32 bit value.

The reasoning for the 8-bit return is that the return will always be 
binary. 0 or non-zero, but by mapping a non-zero value to 1 may make 
more sense than outputing a 32-bit bitmask, which was the initial approach.

> Thanks.
>
> Best Regards,
> Ketul
>

--André Marques.

[snip]