[PATCH v5 01/11] dt-bindings: arm: add cznic,turris-omnia-mcu binding

["Marek Behún" <kabel@kernel.org>]

Add binding for cznic,turris-omnia-mcu, the device-tree node
representing the system-controller features provided by the MCU on the
Turris Omnia router.

Signed-off-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
Changes from v4:
- #gpio-cells changed from 2 (pin number, flags) to 3 (bank, pin number,
  flags). This is because two years ago we added device-tree fixing code
  into U-Boot [1] which adds reset-gpios to PCIe controller nodes if
  these GPIOs are controllable via MCU, and the code adds the gpio
  specifiers to have 3 cells. Implementing this driver with twocell
  specifier breaks PCIe functionality for users which have upgraded U-Boot
- added documentation for #interrupt-cells and #gpio-cells

[1] https://source.denx.de/u-boot/u-boot/-/commit/1da53ae26afc
---
 .../bindings/arm/cznic,turris-omnia-mcu.yaml  | 86 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 87 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/cznic,turris-omnia-mcu.yaml

diff --git a/Documentation/devicetree/bindings/arm/cznic,turris-omnia-mcu.yaml b/Documentation/devicetree/bindings/arm/cznic,turris-omnia-mcu.yaml
new file mode 100644
index 000000000000..dd9ee21ee24d
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/cznic,turris-omnia-mcu.yaml
@@ -0,0 +1,86 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/cznic,turris-omnia-mcu.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: CZ.NIC's Turris Omnia MCU
+
+maintainers:
+  - Marek Behún <kabel@kernel.org>
+
+description:
+  The MCU on Turris Omnia acts as a system controller providing additional
+  GPIOs, interrupts, watchdog, system power off and wakeup configuration.
+
+properties:
+  compatible:
+    const: cznic,turris-omnia-mcu
+
+  reg:
+    description: MCU I2C slave address
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  interrupt-controller: true
+
+  '#interrupt-cells':
+    const: 2
+    description: |
+      The first cell specifies the interrupt number (0 to 63), the second cell
+      specifies interrupt type (which can be one of IRQ_TYPE_EDGE_RISING,
+      IRQ_TYPE_EDGE_FALLING or IRQ_TYPE_EDGE_BOTH).
+      The interrupt numbers correspond sequentially to GPIO numbers, taking the
+      GPIO banks into account:
+        IRQ number   GPIO bank   GPIO pin within bank
+           0 - 15      0           0 - 15
+          16 - 47      1           0 - 31
+          48 - 63      2           0 - 15
+      There are several exceptions:
+        IRQ number   meaning
+          11           LED panel brightness changed by button press
+          13           TRNG entropy ready
+          14           ECDSA message signature computation done
+
+  gpio-controller: true
+
+  '#gpio-cells':
+    const: 3
+    description:
+      The first cell is bank number (0, 1 or 2), the second cell is pin number
+      within the bank (0 to 15 for banks 0 and 2, 0 to 31 for bank 1), and the
+      third cell specifies consumer flags.
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - interrupt-controller
+  - gpio-controller
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        system-controller@2a {
+            compatible = "cznic,turris-omnia-mcu";
+            reg = <0x2a>;
+
+            interrupt-parent = <&gpio1>;
+            interrupts = <11 IRQ_TYPE_NONE>;
+
+            gpio-controller;
+            #gpio-cells = <3>;
+
+            interrupt-controller;
+            #interrupt-cells = <2>;
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index aa3b947fb080..89edfc2b875b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2141,6 +2141,7 @@ W:	https://www.turris.cz/
 F:	Documentation/ABI/testing/debugfs-moxtet
 F:	Documentation/ABI/testing/sysfs-bus-moxtet-devices
 F:	Documentation/ABI/testing/sysfs-firmware-turris-mox-rwtm
+F:	Documentation/devicetree/bindings/arm/cznic,turris-omnia-mcu.yaml
 F:	Documentation/devicetree/bindings/bus/moxtet.txt
 F:	Documentation/devicetree/bindings/firmware/cznic,turris-mox-rwtm.txt
 F:	Documentation/devicetree/bindings/gpio/gpio-moxtet.txt
-- 
2.43.2