Re: [RFC 2.6.27 1/1] gpiolib: add support for batch set of pins

[Jaya Kumar]

On Tue, Dec 30, 2008 at 11:58 PM, Jaya Kumar <jayakumar.lkml@xxxxxxxxx> wrote:
> On Tue, Dec 30, 2008 at 11:55 PM, Robin Getz <rgetz@xxxxxxxxxxxxxxxxxxxx> wrote:
>> Yeah, I hadn't thought about spanning more than one gpio_chip. That's a good
>> point.
>
> The currently posted code already supports spanning more than one gpio_chip.

and btw, that was because the use case needed to span 2, since it
started at 58 and was 16 bits long on a platform where ngpio == 32.
this was explained at the start of the thread.

>
> +       do {
> +               chip = gpio_to_chip(gpio + i);
> +               WARN_ON(extra_checks && chip->can_sleep);
> +
> +               if (!chip->set_bus) {
> +                       while (((gpio + i) < (chip->base + chip->ngpio))
> +                               && bitwidth) {
> +                               value = values & (1 << i);
> +                               chip->set(chip, gpio + i - chip->base, value);
> +                               i++;
> +                               bitwidth--;
> +                       }
> +               } else {
> +                       value = values >> i; /* shift off the used stuff */
> +                       remwidth = ((chip->base + (int) chip->ngpio) -
> +                                       ((int) gpio + i));
> +                       width = min(bitwidth, remwidth);
> +
> +                       chip->set_bus(chip, gpio + i - chip->base, value,
> +                                       width);
> +                       i += width;
> +                       bitwidth -= width;
> +               }
> +       } while (bitwidth);
>
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