| Message ID | 20181116162403.49854-3-lkundrak@v3.sk (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | Add support for OLPC XO 1.75 Embedded Controller | expand |
On Fri, 16 Nov 2018 17:23:48 +0100, 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@v3.sk> > Acked-by: Pavel Machek <pavel@ucw.cz> > > --- > Changes since v1: > - s/cmd-gpio/cmd-gpios/ > - s/ready-gpio/ready-gpios/ in the documentation paragraph > - Remove status = "okay" from the example > > .../bindings/misc/olpc,xo1.75-ec.txt | 23 +++++++++++++++++++ > 1 file changed, 23 insertions(+) > create mode 100644 Documentation/devicetree/bindings/misc/olpc,xo1.75-ec.txt > Reviewed-by: Rob Herring <robh@kernel.org>
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..8c4d649cdd8f --- /dev/null +++ b/Documentation/devicetree/bindings/misc/olpc,xo1.75-ec.txt @@ -0,0 +1,23 @@ +OLPC XO-1.75 Embedded Controller + +Required properties: +- compatible: Should be "olpc,xo1.75-ec". +- cmd-gpios: 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-gpios" property of the +SSP binding as documented in: +<Documentation/devicetree/bindings/spi/spi-pxa2xx.txt>. + +Example: + &ssp3 { + spi-slave; + ready-gpios = <&gpio 125 GPIO_ACTIVE_HIGH>; + + slave { + compatible = "olpc,xo1.75-ec"; + spi-cpha; + cmd-gpios = <&gpio 155 GPIO_ACTIVE_HIGH>; + }; + };