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 <redacted>
---
Changes v2 -> v3:
  - rebase on master
  - fix typo (suggested by Rob Herring)

Changes v1 -> v2:
  - rebase on master
  - remove the simple-bus compatibility as the root node will now
  populate child nodes (suggested by Rob Herring)
  - use the ts vendor prefix for gpios (suggested by Rob Herring)
---
 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 000000000000..905600adfb64
--- /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