diff --git a/Documentation/devicetree/bindings/firmware/intel,ixp4xx-network-processing-engine.yaml b/Documentation/devicetree/bindings/firmware/intel,ixp4xx-network-processing-engine.yaml
index c435c9f369a4..14de9e3d5fab 100644
--- a/Documentation/devicetree/bindings/firmware/intel,ixp4xx-network-processing-engine.yaml
+++ b/Documentation/devicetree/bindings/firmware/intel,ixp4xx-network-processing-engine.yaml
@@ -45,9 +45,29 @@ additionalProperties: false
 
 examples:
   - |
+    #include <dt-bindings/gpio/gpio.h>
+
     npe: npe@c8006000 {
          compatible = "intel,ixp4xx-network-processing-engine";
          reg = <0xc8006000 0x1000>, <0xc8007000 0x1000>, <0xc8008000 0x1000>;
+         #address-cells = <1>;
+         #size-cells = <0>;
+
+         hss@0 {
+             compatible = "intel,ixp4xx-hss";
+             reg = <0>;
+             intel,npe-handle = <&npe 0>;
+             intel,queue-chl-rxtrig = <&qmgr 12>;
+             intel,queue-pkt-rx = <&qmgr 13>;
+             intel,queue-pkt-tx = <&qmgr 14>, <&qmgr 15>, <&qmgr 16>, <&qmgr 17>;
+             intel,queue-pkt-rxfree = <&qmgr 18>, <&qmgr 19>, <&qmgr 20>, <&qmgr 21>;
+             intel,queue-pkt-txdone = <&qmgr 22>;
+             cts-gpios = <&gpio0 10 GPIO_ACTIVE_LOW>;
+             rts-gpios = <&gpio0 14 GPIO_ACTIVE_LOW>;
+             dcd-gpios = <&gpio0 6 GPIO_ACTIVE_LOW>;
+             dtr-gpios = <&gpio_74 2 GPIO_ACTIVE_LOW>;
+             clk-internal-gpios = <&gpio_74 0 GPIO_ACTIVE_HIGH>;
+         };
 
          crypto {
              compatible = "intel,ixp4xx-crypto";
diff --git a/Documentation/devicetree/bindings/net/intel,ixp4xx-hss.yaml b/Documentation/devicetree/bindings/net/intel,ixp4xx-hss.yaml
new file mode 100644
index 000000000000..93d88dbb2073
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/intel,ixp4xx-hss.yaml
@@ -0,0 +1,94 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# Copyright 2021 Linaro Ltd.
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/net/intel,ixp4xx-hss.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: Intel IXP4xx V.35 WAN High Speed Serial Link (HSS)
+
+maintainers:
+  - Linus Walleij <linus.walleij@linaro.org>
+
+description: |
+  The Intel IXP4xx HSS makes use of the IXP4xx NPE (Network
+  Processing Engine) and the IXP4xx Queue Manager to process
+  V.35 Wideband Modem (WAN) links.
+
+properties:
+  compatible:
+    const: intel,ixp4xx-hss
+
+  reg:
+    maxItems: 1
+    description: The HSS instance
+
+  intel,npe-handle:
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    maxItems: 1
+    description: phandle to the NPE this HSS instance is using
+      and the instance to use in the second cell
+
+  intel,queue-chl-rxtrig:
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    maxItems: 1
+    description: phandle to the RX trigger queue on the NPE
+
+  intel,queue-pkt-rx:
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    maxItems: 1
+    description: phandle to the packet RX queue on the NPE
+
+  intel,queue-pkt-tx:
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    maxItems: 4
+    description: phandle to the packet TX0, TX1, TX2 and TX3 queues on the NPE
+
+  intel,queue-pkt-rxfree:
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    maxItems: 4
+    description: phandle to the packet RXFREE0, RXFREE1, RXFREE2 and
+      RXFREE3 queues on the NPE
+
+  intel,queue-pkt-txdone:
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    maxItems: 1
+    description: phandle to the packet TXDONE queue on the NPE
+
+  cts-gpios:
+    maxItems: 1
+    description: Clear To Send (CTS) GPIO line
+
+  rts-gpios:
+    maxItems: 1
+    description: Ready To Send (RTS) GPIO line
+
+  dcd-gpios:
+    maxItems: 1
+    description: Data Carrier Detect (DCD) GPIO line
+
+  dtr-gpios:
+    maxItems: 1
+    description: Data Terminal Ready (DTR) GPIO line
+
+  clk-internal-gpios:
+    maxItems: 1
+    description: Clock internal GPIO line, driving this high will make the HSS
+      use internal clocking as opposed to external clocking
+
+required:
+  - compatible
+  - reg
+  - intel,npe-handle
+  - intel,queue-chl-rxtrig
+  - intel,queue-pkt-rx
+  - intel,queue-pkt-tx
+  - intel,queue-pkt-rxfree
+  - intel,queue-pkt-txdone
+  - cts-gpios
+  - rts-gpios
+  - dcd-gpios
+  - dtr-gpios
+  - clk-internal-gpios
+
+additionalProperties: false
