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>
---
.../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>;
+ };
+ };
--
2.19.0
