SA8255p platform abstracts resources such as resets, clocks and
regulators in firmware. The SCMI firmware exposes multiple protocols to
control such resources which are identified by protocol_id.

For this USB phy, 2 SCMI protocols are exposed by the firmware:
* power domain management protocol (protocol_id=0x11)
* performance domain management protocol (protocol_id=0x13)

The power domain has 2 indices: 'core' and 'transfer'.
* core controls the regulators, the clocks and the reset
* transfer only controls the clocks

For example, to power on/off the PHY, we should use the 'core' domain.
To disable data transfer and keeping power enabled, we should use the
'transfer' domain.

Add a new binding for the Qualcomm SA8255p Synopsys Femto High-Speed
USB PHY V2 found in SA8255P.

Note: the performance domain (0x13) exposes opaques values (0xa to 0x11)
for which we don't have any information. Since it is not mandatory
for the PHY to be functional, we have ommited it from the bindings.
We can document it (and make them part of the dt ABI) once we have more
information.

Signed-off-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
---
 .../bindings/phy/qcom,sa8255p-usb-hs-phy.yaml      | 52 ++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/Documentation/devicetree/bindings/phy/qcom,sa8255p-usb-hs-phy.yaml b/Documentation/devicetree/bindings/phy/qcom,sa8255p-usb-hs-phy.yaml
new file mode 100644
index 000000000000..fff474a8345d
--- /dev/null
+++ b/Documentation/devicetree/bindings/phy/qcom,sa8255p-usb-hs-phy.yaml
@@ -0,0 +1,52 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/qcom,sa8255p-usb-hs-phy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm SA8255p Synopsys Femto High-Speed USB PHY V2
+
+maintainers:
+  - Mattijs Korpershoek <mkorpershoek@kernel.org>
+
+properties:
+  compatible:
+    const: qcom,sa8255p-usb-hs-phy
+
+  reg:
+    maxItems: 1
+
+  "#phy-cells":
+    const: 0
+
+  power-domains:
+    maxItems: 2
+
+  power-domain-names:
+    items:
+      - const: core
+      - const: transfer
+
+required:
+  - compatible
+  - reg
+  - "#phy-cells"
+  - power-domains
+  - power-domain-names
+
+additionalProperties: false
+
+examples:
+  - |
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        phy@88e4000 {
+            compatible = "qcom,sa8255p-usb-hs-phy";
+            reg = <0x0 0x088e4000 0x0 0x120>;
+            #phy-cells = <0>;
+            power-domains = <&scmi12_pd 1>, <&scmi12_pd 0>;
+            power-domain-names = "core", "transfer";
+        };
+    };
-- 
2.55.0