dt-bindings: bus: Add documentation for the Technologic Systems NBUS

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>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/Documentation/devicetree/bindings/bus/ts-nbus.txt b/Documentation/devicetree/bindings/bus/ts-nbus.txt
new file mode 100644 (file)
index 0000000..2a10d06
--- /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"
+ - #address-cells      : must be 1
+ - #size-cells         : must be 0
+ - pwms                        : The PWM bound to the FPGA
+ - ts,data-gpios       : The 8 GPIO pins connected to the data lines on the FPGA
+ - ts,csn-gpios                : The GPIO pin connected to the csn line on the FPGA
+ - ts,txrx-gpios       : The GPIO pin connected to the txrx line on the FPGA
+ - ts,strobe-gpios     : The GPIO pin connected to the stobe line on the FPGA
+ - ts,ale-gpios                : The GPIO pin connected to the ale line on the FPGA
+ - ts,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";
+               pinctrl-0 = <&nbus_pins>;
+               #address-cells = <1>;
+               #size-cells = <0>;
+               pwms = <&pwm 2 83>;
+               ts,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>;
+               ts,csn-gpios    = <&gpio0 16 GPIO_ACTIVE_HIGH>;
+               ts,txrx-gpios   = <&gpio0 24 GPIO_ACTIVE_HIGH>;
+               ts,strobe-gpios = <&gpio0 25 GPIO_ACTIVE_HIGH>;
+               ts,ale-gpios    = <&gpio0 26 GPIO_ACTIVE_HIGH>;
+               ts,rdy-gpios    = <&gpio0 21 GPIO_ACTIVE_HIGH>;
+
+               watchdog@2a {
+                       compatible = "...";
+
+                       /* ... */
+               };
+       };