[PATCH v3 1/8] rsb: Add generic Reduced Serial Bus (RSB) controller binding documentation

[Chen-Yu Tsai <wens@csie.org>]

Reduced Serial Bus is a proprietary 2-line push-pull serial bus
supporting multiple slave devices.

It was developed by Allwinner, Inc. and used by Allwinner and X-Powers,
Inc. for their line of PMICs and other peripheral ICs.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
 Documentation/devicetree/bindings/rsb/rsb.txt | 50 +++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rsb/rsb.txt

diff --git a/Documentation/devicetree/bindings/rsb/rsb.txt b/Documentation/devicetree/bindings/rsb/rsb.txt
new file mode 100644
index 000000000000..0b027948ca9c
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+Reduced Serial Bus (RSB) Controller
+
+This document defines a generic set of bindings for use by RSB controllers.
+A controller is modelled in device tree as a node with zero or more child
+nodes, each representing a unique slave device on the bus.
+
+Required properties:
+
+ - #address-cells : must be 2
+ - #size-cells : must be 0
+
+Optional properties:
+
+ - clock-frequency : Desired bus clock frequency in Hz. Maximum is 20 MHz.
+
+Child nodes:
+
+An RSB controller node can contain zero or more child nodes representing
+slave devices on the bus.  Child 'reg' properties are specified as a
+runtime address, hardware address pair. The hardware address is hardwired
+in the device, which can normally be found in the datasheet. The runtime
+address is set by software. No 2 devices on the same bus shall have the
+same runtime address.
+
+Valid runtime addresses - There are only 15 valid runtime addresses:
+
+    0x17, 0x2d, 0x3a, 0x4e, 0x59, 0x63, 0x74, 0x8b,
+    0x9c, 0xa6, 0xb1, 0xc5, 0xd2, 0xe8, 0xff
+
+It is highly recommended that one choose the same runtime addresses as
+vendor BSPs use so that a) the addresses remain the same across different
+software systems, and b) addresses of supported and listed slave devices
+don't conflict with unsupported or not yet listed devices.
+
+Example:
+
+	rsb@... {
+		compatible = "...";
+		reg = <...>;
+		/* ... */
+		#address-cells = <2>;
+		#size-cells = <0>;
+
+		pmic@2d {
+			compatible = "...";
+			reg = <0x2d 0x3e3>;
+
+			/* ... */
+		};
+	};
-- 
2.5.0