[PATCH v9 2/5] dt-bindings: phy: Add documentation for Airoha AN7581 USB PHY

[Christian Marangi]

Add documentation for Airoha AN7581 USB PHY that describe the USB PHY
for the USB controller.

Airoha AN7581 SoC support a maximum of 2 USB port. The USB 2.0 mode is
always supported. The USB 3.0 mode is optional and depends on the Serdes
mode currently configured on the system for the relevant USB port.

To correctly calibrate, the USB 2.0 port require correct value in
"airoha,usb2-monitor-clk-sel" property. Both the 2 USB 2.0 port permit
selecting one of the 4 monitor clock for calibration (internal clock not
exposed to the system) but each port have only one of the 4 actually
connected in HW hence the correct value needs to be specified in DT
based on board and the physical port. Normally it's monitor clock 1 for
USB1 and monitor clock 2 for USB2.

To correctly setup the Serdes mode attached to the USB 3.0 mode, a phys
property is required with the phandle pointing to the correct Serdes port
provided by the SCU node. Providing the phys property is optional if USB
3.0 is not used.

Signed-off-by: Christian Marangi <ansuelsmth at gmail.com>
---
 .../bindings/phy/airoha,an7581-usb-phy.yaml   | 62 +++++++++++++++++++
 MAINTAINERS                                   |  6 ++
 2 files changed, 68 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/phy/airoha,an7581-usb-phy.yaml

diff --git a/Documentation/devicetree/bindings/phy/airoha,an7581-usb-phy.yaml b/Documentation/devicetree/bindings/phy/airoha,an7581-usb-phy.yaml
new file mode 100644
index 000000000000..f42e3d49a61f
--- /dev/null
+++ b/Documentation/devicetree/bindings/phy/airoha,an7581-usb-phy.yaml
@@ -0,0 +1,62 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/airoha,an7581-usb-phy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Airoha AN7581 SoC USB PHY
+
+maintainers:
+  - Christian Marangi <ansuelsmth at gmail.com>
+
+description: >
+  The Airoha AN7581 SoC USB PHY describes the USB PHY for the USB controller.
+
+  Airoha AN7581 SoC support a maximum of 2 USB port. The USB 2.0 mode is
+  always supported. The USB 3.0 mode is optional and depends on the Serdes
+  mode currently configured on the system for the relevant USB port.
+
+properties:
+  compatible:
+    const: airoha,an7581-usb-phy
+
+  reg:
+    maxItems: 1
+
+  airoha,usb2-monitor-clk-sel:
+    description: Describe what oscillator across the available 4
+      should be selected for USB 2.0 Slew Rate calibration.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [0, 1, 2, 3]
+
+  phys:
+    items:
+      - description: phandle to Serdes PHY. Optional if USB 3.0 is not used.
+
+  '#phy-cells':
+    description: The cell contains the mode, PHY_TYPE_USB2 or PHY_TYPE_USB3,
+      as defined in dt-bindings/phy/phy.h.
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - airoha,usb2-monitor-clk-sel
+  - '#phy-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/soc/airoha,scu-ssr.h>
+
+    phy at 1fac0000 {
+        compatible = "airoha,an7581-usb-phy";
+        reg = <0x1fac0000 0x10000>;
+
+        airoha,usb2-monitor-clk-sel = <1>;
+        phys = <&scu AIROHA_SCU_SERDES_USB1>;
+
+        #phy-cells = <1>;
+    };
+
diff --git a/MAINTAINERS b/MAINTAINERS
index 21c0ef0b9ce5..932044785a39 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -771,6 +771,12 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/spi/airoha,en7581-snand.yaml
 F:	drivers/spi/spi-airoha-snfi.c
 
+AIROHA USB PHY DRIVER
+M:	Christian Marangi <ansuelsmth at gmail.com>
+L:	linux-arm-kernel at lists.infradead.org (moderated for non-subscribers)
+S:	Maintained
+F:	Documentation/devicetree/bindings/phy/airoha,an7581-usb-phy.yaml
+
 AIRSPY MEDIA DRIVER
 L:	linux-media at vger.kernel.org
 S:	Orphan
-- 
2.53.0