[Ksummit-discuss] [TECH TOPIC] Sensors and similar - subsystem interactions, divisions, bindings etc.

[Linus Walleij]

On Thu, Jul 28, 2016 at 8:08 PM, Lars-Peter Clausen <lars at metafoo.de> wrote:
> On 07/28/2016 06:46 PM, Laurent Pinchart wrote:
>> Are you aware of any GPIO
>> hardware that can be programmed to sample at a precise point in time (or
>> perhaps even periodically) ?
>
> I have such hardware. It's custom hardware, non-public at the moment.
>
> But it works like this, for each pin you can configure whether it can be
> controlled independently, like a normal GPIO, or whether the values are
> sampled/updated to/from a continuous data stream that is regularly
> clocked (basically a 1-bit ADC/DAC). This falls right on the edge
> between GPIO and IIO and I'm really torn where to put it. For now I went
> with IIO since it predates the chardev GPIO interface and because of all
> the libiio magic.

I guess either GPIO should reuse the IIO triggers, or we create something
in IIO that uses GPIO from inside the kernel and add get_multiple() as
similar to set_multiple() to the API and thus make a generic GPIO sampler
driver in IIO that can reuse the IIO triggers, while using a plain GPIO
driver as back-end. If the APIs can be made precise enough.

We can even add get_multiple_with_timestamp() if need be to be
able to contain it in gpiolib.

Yours,
Linus Walleij