[v5 1/2] dt-bindings: gpio: aspeed: Add SGPIO support

Linus Walleij linus.walleij at linaro.org
Tue Jul 30 07:57:16 AEST 2019

On Mon, Jul 29, 2019 at 2:19 AM Andrew Jeffery <andrew at aj.id.au> wrote:

> The behaviour is to periodically emit the state of all enabled GPIOs
> (i.e. the ngpios value), one per bus clock cycle. There's no explicit
> addressing scheme, the protocol encodes the value for a given GPIO
> by its position in the data stream relative to a pulse on the "load data"
> (LD) line, whose envelope covers the clock cycle for the last GPIO in
> the sequence. Similar to SPI the bus has both out and in lines, which
> cater to output/input GPIOs.
> A rough timing diagram for a 16-GPIO configuration looks like what
> I've pasted here:
> https://gist.github.com/amboar/c9543af1957854474b8c05ab357f0675

OK that is complex. I agree we need to keep this driver together.

Linus Walleij

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