[PATCH] dt-bindings: usb: Add binding for Microchip usb5744 hub controller

[Michal Simek]

The Microchip usb5744 is a SS/HS USB 3.0 hub controller with 4 ports.
The binding describes USB related aspects of the USB5744 hub, it as
well cover the option of connecting the controller as an i2c slave.
When i2c interface is connected hub needs to be initialized first.
Hub itself has fixed i2c address 0x2D but hardcoding address is not good
idea because address can be shifted by i2c address translator in the
middle.

Signed-off-by: Piyush Mehta <piyush.mehta@xxxxxxx>
Signed-off-by: Michal Simek <michal.simek@xxxxxxx>
---

It looks like that usb8041 has also an optional i2c interface which is not
covered. But it is mentioned at commit 40e58a8a7ca6 ("dt-bindings: usb:
Add binding for TI USB8041 hub controller").

i2c-bus name property was suggested by Rob at
https://lore.kernel.org/all/CAL_JsqJedhX6typpUKbnzV7CLK6UZVjq3CyG9iY_j5DLPqvVdw@xxxxxxxxxxxxxx/
and
https://lore.kernel.org/all/CAL_JsqJZBbu+UXqUNdZwg-uv0PAsNg55026PTwhKr5wQtxCjVQ@xxxxxxxxxxxxxx/

the question is if adding address like this is acceptable.
But it must be specified.

Driver will follow based on final dt-binding.

---
 .../bindings/usb/microchip,usb5744.yaml       | 85 +++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/usb/microchip,usb5744.yaml

diff --git a/Documentation/devicetree/bindings/usb/microchip,usb5744.yaml b/Documentation/devicetree/bindings/usb/microchip,usb5744.yaml
new file mode 100644
index 000000000000..fafe275a35df
--- /dev/null
+++ b/Documentation/devicetree/bindings/usb/microchip,usb5744.yaml
@@ -0,0 +1,85 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/usb/microchip,usb5744.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip USB5744 4-port Hub Controller
+
+description:
+  Microchip's USB5744 SmartHubTM IC is a 4 port, SuperSpeed (SS)/Hi-Speed (HS),
+  low power, low pin count configurable and fully compliant with the USB 3.1
+  Gen 1 specification. The USB5744 also supports Full Speed (FS) and Low Speed
+  (LS) USB signaling, offering complete coverage of all defined USB operating
+  speeds. The new SuperSpeed hubs operate in parallel with the USB 2.0
+  controller, so 5 Gbps SuperSpeed data transfers are not affected by slower
+  USB 2.0 traffic.
+
+maintainers:
+  - Piyush Mehta <piyush.mehta@xxxxxxx>
+  - Michal Simek <michal.simek@xxxxxxx>
+
+allOf:
+  - $ref: usb-device.yaml#
+
+properties:
+  compatible:
+    enum:
+      - usb424,5744
+      - usb424,2744
+
+  reg: true
+
+  reset-gpios:
+    maxItems: 1
+    description:
+      GPIO controlling the GRST# pin.
+
+  vdd-supply:
+    description:
+      VDD power supply to the hub
+
+  peer-hub:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      phandle to the peer hub on the controller.
+
+  i2c-bus:
+    maxItems: 1
+    description:
+      phandle of an I2C controller to link usb-hub for usb attach and reset
+      followed by i2c address.
+
+required:
+  - compatible
+  - reg
+  - peer-hub
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    usb {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        /* 2.0 hub on port 1 */
+        hub_2_0: hub@1 {
+          compatible = "usb424,5744";
+          reg = <1>;
+          peer-hub = <&hub_3_0>;
+          i2c-bus = <&i2c 0x2d>;
+          reset-gpios = <&gpio 3 GPIO_ACTIVE_LOW>;
+        };
+
+        /* 3.0 hub on port 2 */
+        hub_3_0: hub@2 {
+          compatible = "usb424,2744";
+          reg = <2>;
+          peer-hub = <&hub_2_0>;
+          i2c-bus = <&i2c 0x2d>;
+          reset-gpios = <&gpio 3 GPIO_ACTIVE_LOW>;
+        };
+    };
-- 
2.36.1