[v6,01/10] dt-bindings: olpc,xo1.75-ec: Add OLPC XO-1.75 EC bindings
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Message ID 20190424074353.458446-2-lkundrak@v3.sk
State Not Applicable, archived
Headers show
  • Add support for OLPC XO 1.75 Embedded Controller
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Commit Message

Lubomir Rintel April 24, 2019, 7:43 a.m. UTC
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>
Reviewed-by: Rob Herring <robh@kernel.org>

Changes since v5:
- Added Rob Herring's Reviewed-by tag

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

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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:
+	&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>;
+		};
+	};