linux-kernel - [PATCH v5 01/10] dt-bindings: olpc,xo1.75-ec: Add OLPC XO-1.75 EC bindings

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Message-Id: <20190110175845.1203986-2-lkundrak@v3.sk>
Date:   Thu, 10 Jan 2019 18:58:36 +0100
From:   Lubomir Rintel <lkundrak@...sk>
To:     Andy Shevchenko <andy@...radead.org>,
        Darren Hart <dvhart@...radead.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Mark Rutland <mark.rutland@....com>,
        platform-driver-x86@...r.kernel.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Lubomir Rintel <lkundrak@...sk>, Pavel Machek <pavel@....cz>
Subject: [PATCH v5 01/10] dt-bindings: olpc,xo1.75-ec: Add OLPC XO-1.75 EC bindings

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@...sk>
Acked-by: Pavel Machek <pavel@....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

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>;
+		};
+	};
-- 
2.20.1