[PATCH 3/6] dt-bindings: bus: Add documentation for the Technologic Systems NBUS

[Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>]

Add binding documentation for the Technologic Systems NBUS that is used
to interface with peripherals in the FPGA of the TS-4600 SoM.

Signed-off-by: Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>
---
 Documentation/devicetree/bindings/bus/ts-nbus.txt | 50 +++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/bus/ts-nbus.txt

diff --git a/Documentation/devicetree/bindings/bus/ts-nbus.txt b/Documentation/devicetree/bindings/bus/ts-nbus.txt
new file mode 100644
index 0000000..2f777ee
--- /dev/null
+++ b/Documentation/devicetree/bindings/bus/ts-nbus.txt
@@ -0,0 +1,50 @@
+Technologic Systems NBUS
+
+The NBUS is a bus used to interface with peripherals in the Technologic
+Systems FPGA on the TS-4600 SoM.
+
+Required properties :
+ - compatible     : "technologic,ts-nbus", "simple-bus"
+ - #address-cells : must be 1
+ - #size-cells    : must be 0
+ - pws            : The PWM pin connected to the clock line on the FPGA
+ - data-gpios	  : The GPIO pin connected to the data line on the FPGA
+ - csn-gpios	  : The GPIO pin connected to the csn line on the FPGA
+ - txrx-gpios	  : The GPIO pin connected to the txrx line on the FPGA
+ - strobe-gpios	  : The GPIO pin connected to the stobe line on the FPGA
+ - ale-gpios	  : The GPIO pin connected to the ale line on the FPGA
+ - rdy-gpios	  : The GPIO pin connected to the rdy line on the FPGA
+
+Child nodes:
+
+The NBUS node can contain zero or more child nodes representing peripherals
+on the bus.
+
+Example:
+
+	nbus {
+		compatible = "technologic,ts-nbus", "simple-bus";
+		pinctrl-0 = <&nbus_pins>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		pwms = <&pwm 2 83>;
+		data-gpios   = <&gpio0 0 GPIO_ACTIVE_HIGH
+				&gpio0 1 GPIO_ACTIVE_HIGH
+				&gpio0 2 GPIO_ACTIVE_HIGH
+				&gpio0 3 GPIO_ACTIVE_HIGH
+				&gpio0 4 GPIO_ACTIVE_HIGH
+				&gpio0 5 GPIO_ACTIVE_HIGH
+				&gpio0 6 GPIO_ACTIVE_HIGH
+				&gpio0 7 GPIO_ACTIVE_HIGH>;
+		csn-gpios    = <&gpio0 16 GPIO_ACTIVE_HIGH>;
+		txrx-gpios   = <&gpio0 24 GPIO_ACTIVE_HIGH>;
+		strobe-gpios = <&gpio0 25 GPIO_ACTIVE_HIGH>;
+		ale-gpios    = <&gpio0 26 GPIO_ACTIVE_HIGH>;
+		rdy-gpios    = <&gpio0 21 GPIO_ACTIVE_HIGH>;
+
+		wdt@2a {
+			compatible = "...";
+
+			/* ... */
+		};
+	};
-- 
2.10.2