dts: bindings: add nrf-fll16m and nrf-lfclk bindings

Add bindings for nrf-fll16m and nrf-lfclk and update in-tree nodes
and boards to use them in place of the fixed-clock binding.

Signed-off-by: Bjarki Arge Andreasen <bjarki.andreasen@nordicsemi.no>

dts/bindings/clock/nordic,nrf-fll16m.yaml

@@ -0,0 +1,42 @@
+# Copyright (c) 2024 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+  Nordic FLL16M
+
+  The FLL16M can use the following clocks as clock sources:
+
+    - HFXO: The HFXO clock is used as a clock source if the
+      FLL16M mode is BYPASS, or if the FLL16M mode is
+      closed-loop and the LFXO clock is not available.
+
+    - LFXO: The LFXO clock is used as a clock source if the
+      FLL16M mode is closed-loop and the LFXO clock is
+      available.
+
+  Devicetree example:
+
+    fll16m {
+            open-loop-accuracy-ppm = <20000>;
+            closed-loop-base-accuracy-ppm = <5000>;
+            clocks = <&hfxo>, <&lfxo>;
+            clock-names = "hfxo", "lfxo";
+    };
+
+compatible: "nordic,nrf-fll16m"
+
+include: fixed-clock.yaml
+
+properties:
+  clock-frequency:
+    const: 16000000
+
+  open-loop-accuracy-ppm:
+    type: int
+    description: Clock accuracy in parts per million if open-loop clock source is used.
+
+  closed-loop-base-accuracy-ppm:
+    type: int
+    description: |
+      Base clock accuracy in parts per million if closed-loop clock source is used.
+      The actual accuracy is this property plus the accuracy of the HFXO or LFXO.

dts/bindings/clock/nordic,nrf-lfclk.yaml

@@ -0,0 +1,42 @@
+# Copyright (c) 2024 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+  nRF LFCLK (Low Frequency CLocK)
+
+  The LFCLK can use the following clocks as clock sources:
+
+    - HFXO: The HFXO clock is used as a clock source if the
+      LFCLK SYNTH mode is selected and the LFXO clock is not
+      available. The HFXO clock is used indirectly through
+      the FLL16M clock in BYPASS mode.
+
+    - LFXO: The LFXO clock is used as a clock source if the
+      LFCLK SYNTH mode is selected and the LFXO clock is
+      available. The LFXO clock is used indirectly through
+      the FLL16M clock in BYPASS mode.
+
+  Devicetree example:
+
+    lfclk {
+            lfrc-accuracy-ppm = <500>;
+            lflprc-accuracy-ppm = <1000>;
+            clocks = <&hfxo>, <&lfxo>;
+            clock-names = "hfxo", "lfxo";
+    };
+
+compatible: "nordic,nrf-lfclk"
+
+include: fixed-clock.yaml
+
+properties:
+  clock-frequency:
+    const: 32768
+
+  lfrc-accuracy-ppm:
+    type: int
+    description: Clock accuracy in parts per million if LFRC clock source is used.
+
+  lflprc-accuracy-ppm:
+    type: int
+    description: Clock accuracy in parts per million if LFLPRC clock source is used.

dts/common/nordic/nrf54h20.dtsi

@@ -156,9 +156,13 @@
 		};
 
 		fll16m: fll16m {
-			compatible = "fixed-clock";
+			compatible = "nordic,nrf-fll16m";
 			#clock-cells = <0>;
 			clock-frequency = <DT_FREQ_M(16)>;
+			open-loop-accuracy-ppm = <20000>;
+			closed-loop-base-accuracy-ppm = <5000>;
+			clocks = <&hfxo>, <&lfxo>;
+			clock-names = "hfxo", "lfxo";
 		};
 
 		hsfll120: hsfll120 {
@@ -169,9 +173,14 @@
 		};
 
 		lfclk: lfclk {
-			compatible = "fixed-clock";
+			compatible = "nordic,nrf-lfclk";
 			#clock-cells = <0>;
 			clock-frequency = <32768>;
+			status = "okay";
+			lfrc-accuracy-ppm = <500>;
+			lflprc-accuracy-ppm = <1000>;
+			clocks = <&hfxo>, <&lfxo>;
+			clock-names = "hfxo", "lfxo";
 		};
 	};