On Wed 2018-10-10 19:22:48, Lubomir Rintel wrote:
> The OLPC XO-1.75 Embedded Controller is a SPI master that uses extra
> signals for handshaking. It needs to know when is the slave (Linux)
> side's TX FIFO ready for transfer (the ready-gpio signal on the SPI
> controller node) and when does it wish to respond with a command (the
> cmd-gpio property).
>
> Signed-off-by: Lubomir Rintel <lkundrak@xxxxx>
Acked-by: Pavel Machek <pavel@xxxxxx>
> ---
> .../bindings/misc/olpc,xo1.75-ec.txt | 24 +++++++++++++++++++
> 1 file changed, 24 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/misc/olpc,xo1.75-ec.txt
>
> diff --git a/Documentation/devicetree/bindings/misc/olpc,xo1.75-ec.txt b/Documentation/devicetree/bindings/misc/olpc,xo1.75-ec.txt
> new file mode 100644
> index 000000000000..14385fee65d2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/olpc,xo1.75-ec.txt
> @@ -0,0 +1,24 @@
> +OLPC XO-1.75 Embedded Controller
> +
> +Required properties:
> +- compatible: Should be "olpc,xo1.75-ec".
> +- cmd-gpio: gpio specifier of the CMD pin
> +
> +The embedded controller requires the SPI controller driver to signal readiness
> +to receive a transfer (that is, when TX FIFO contains the response data) by
> +strobing the ACK pin with the ready signal. See the "ready-gpio" property of the
> +SSP binding as documented in:
> +<Documentation/devicetree/bindings/spi/spi-pxa2xx.txt>.
> +
> +Example:
> + &ssp3 {
> + spi-slave;
> + status = "okay";
> + ready-gpio = <&gpio 125 GPIO_ACTIVE_HIGH>;
> +
> + slave {
> + compatible = "olpc,xo1.75-ec";
> + spi-cpha;
> + cmd-gpio = <&gpio 155 GPIO_ACTIVE_HIGH>;
> + };
> + };
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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