[PATCH 2/8] dt-bindings: connector: Add MikorBUS connector

[Ayush Singh <ayush@beagleboard.org>]

Add DT bindings for mikroBUS interface. MikroBUS [0] is an open standard
developed by MikroElektronika for connecting add-on boards to
microcontrollers or microprocessors.

MikroBUS connector node will optionally act as nexus nodes for routing
GPIOs and PWM.

For GPIOs, the following pin numbering should be followed:

  0: PWM
  1: INT
  2: RX
  3: TX
  4: SCL
  5: SDA
  6: MOSI
  7: MISO
  8: SCK
  9: CS
  10: RST
  11: AN

For PWM, the PWM pin should be on channel 0.

I am not quite sure how to deal with the nexus node properties
(#gpio-cells, gpio-map, gpio-map-mask, gpio-map-pass-thru) since they
seem to conflict with upstream gpio schema (gpio-controller is a
dependency of #gpio-cells).

[0]: https://www.mikroe.com/

Signed-off-by: Ayush Singh <ayush@beagleboard.org>
---
 .../bindings/connector/mikrobus-connector.yaml     | 40 ++++++++++++++++++++++
 MAINTAINERS                                        |  5 +++
 2 files changed, 45 insertions(+)

diff --git a/Documentation/devicetree/bindings/connector/mikrobus-connector.yaml b/Documentation/devicetree/bindings/connector/mikrobus-connector.yaml
new file mode 100644
index 000000000000..603e4627076c
--- /dev/null
+++ b/Documentation/devicetree/bindings/connector/mikrobus-connector.yaml
@@ -0,0 +1,40 @@
+# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+#
+# Copyright (c) Ayush Singh <ayush@beagleboard.org>
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/connector/mikrobus-connector.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: mikroBUS add-on board socket
+
+maintainers:
+  - Ayush Singh <ayush@beagleboard.org>
+
+properties:
+  compatible:
+    const: mikrobus-connector
+
+required:
+  - compatible
+
+additionalProperties: true
+
+examples:
+  - |
+    mikrobus_connector0: mikrobus-connector0 {
+      status = "okay";
+      compatible = "mikrobus-connector";
+
+      #gpio-cells = <2>;
+      gpio-map =
+      <0 0 &main_gpio1 11 0>, <1 0 &main_gpio1 9 0>,
+      <2 0 &main_gpio1 24 0>, <3 0 &main_gpio1 25 0>,
+      <4 0 &main_gpio1 22 0>, <5 0 &main_gpio1 23 0>,
+      <6 0 &main_gpio1 7 0>, <7 0 &main_gpio1 8 0>,
+      <8 0 &main_gpio1 14 0>, <9 0 &main_gpio1 13 0>,
+      <10 0 &main_gpio1 12 0>, <11 0 &main_gpio1 10 0>;
+      gpio-map-mask = <0xf 0x0>;
+      gpio-map-pass-thru = <0x0 0x1>;
+    };
+
diff --git a/MAINTAINERS b/MAINTAINERS
index 0a3d9e17295a..0cc27446b18a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15429,6 +15429,11 @@ M:	Oliver Neukum <oliver@neukum.org>
 S:	Maintained
 F:	drivers/usb/image/microtek.*
 
+MIKROBUS CONNECTOR
+M:	Ayush Singh <ayush@beagleboard.org>
+S:	Maintained
+F:	Documentation/devicetree/bindings/connector/mikrobus-connector.yaml
+
 MIKROTIK CRS3XX 98DX3236 BOARD SUPPORT
 M:	Luka Kovacic <luka.kovacic@sartura.hr>
 M:	Luka Perkov <luka.perkov@sartura.hr>

-- 
2.46.0