Thread (27 messages) 27 messages, 5 authors, 2026-03-22

Re: [PATCH 5/5] dt-bindings: iio: adc: xilinx-xadc: convert to YAML format

From: Krzysztof Kozlowski <krzk@kernel.org>
Date: 2026-02-21 10:38:29
Also in: linux-devicetree, linux-iio, lkml

On Fri, Feb 20, 2026 at 11:09:41AM +0530, Sai Krishna Potthuri wrote:
quoted hunk ↗ jump to hunk
Convert the xilinx-xadc.txt Devicetree binding to a YAML schema format
and remove the old text binding.

Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
---
 .../bindings/iio/adc/xilinx-xadc.txt          | 141 -------------
 .../bindings/iio/adc/xilinx-xadc.yaml         | 194 ++++++++++++++++++
 2 files changed, 194 insertions(+), 141 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt
 create mode 100644 Documentation/devicetree/bindings/iio/adc/xilinx-xadc.yaml
diff --git a/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt b/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt
deleted file mode 100644
index f42e18078376..000000000000
--- a/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt
+++ /dev/null
@@ -1,141 +0,0 @@
-Xilinx XADC device driver
-
-This binding document describes the bindings for the Xilinx 7 Series XADC as well
-as the UltraScale/UltraScale+ System Monitor.
-
-The Xilinx XADC is an ADC that can be found in the Series 7 FPGAs from Xilinx.
-The XADC has a DRP interface for communication. Currently two different
-frontends for the DRP interface exist. One that is only available on the ZYNQ
-family as a hardmacro in the SoC portion of the ZYNQ. The other one is available
-on all series 7 platforms and is a softmacro with a AXI interface. This binding
-document describes the bindings for both of them since the bindings are very
-similar.
-
-The Xilinx System Monitor is an ADC that is found in the UltraScale and
-UltraScale+ FPGAs from Xilinx. The System Monitor provides a DRP interface for
-communication. Xilinx provides a standard IP core that can be used to access the
-System Monitor through an AXI interface in the FPGA fabric. This IP core is
-called the Xilinx System Management Wizard. This document describes the bindings
-for this IP.
-
-Required properties:
-	- compatible: Should be one of
-		* "xlnx,zynq-xadc-1.00.a": When using the ZYNQ device
-		  configuration interface to interface to the XADC hardmacro.
-		* "xlnx,axi-xadc-1.00.a": When using the axi-xadc pcore to
-		  interface to the XADC hardmacro.
-		* "xlnx,system-management-wiz-1.3": When using the
-		  Xilinx System Management Wizard fabric IP core to access the
-		  UltraScale and UltraScale+ System Monitor.
-	- reg: Address and length of the register set for the device
-	- interrupts: Interrupt for the XADC control interface.
-	- clocks: When using the ZYNQ this must be the ZYNQ PCAP clock,
-	  when using the axi-xadc or the axi-system-management-wizard this must be
-	  the clock that provides the clock to the AXI bus interface of the core.
-
-Optional properties:
-	- xlnx,external-mux:
-		* "none": No external multiplexer is used, this is the default
-		  if the property is omitted.
-		* "single": External multiplexer mode is used with one
-		   multiplexer.
-		* "dual": External multiplexer mode is used with two
-		  multiplexers for simultaneous sampling.
-	- xlnx,external-mux-channel: Configures which pair of pins is used to
-	  sample data in external mux mode.
-	  Valid values for single external multiplexer mode are:
-		0: VP/VN
-		1: VAUXP[0]/VAUXN[0]
-		2: VAUXP[1]/VAUXN[1]
-		...
-		16: VAUXP[15]/VAUXN[15]
-	  Valid values for dual external multiplexer mode are:
-		1: VAUXP[0]/VAUXN[0] - VAUXP[8]/VAUXN[8]
-		2: VAUXP[1]/VAUXN[1] - VAUXP[9]/VAUXN[9]
-		...
-		8: VAUXP[7]/VAUXN[7] - VAUXP[15]/VAUXN[15]
-
-	  This property needs to be present if the device is configured for
-	  external multiplexer mode (either single or dual). If the device is
-	  not using external multiplexer mode the property is ignored.
-	- xnlx,channels: List of external channels that are connected to the ADC
-	  Required properties:
-		* #address-cells: Should be 1.
-		* #size-cells: Should be 0.
-
-	  The child nodes of this node represent the external channels which are
-	  connected to the ADC. If the property is no present no external
-	  channels will be assumed to be connected.
-
-	  Each child node represents one channel and has the following
-	  properties:
-		Required properties:
-			* reg: Pair of pins the channel is connected to.
-				0: VP/VN
-				1: VAUXP[0]/VAUXN[0]
-				2: VAUXP[1]/VAUXN[1]
-				...
-				16: VAUXP[15]/VAUXN[15]
-			  Note each channel number should only be used at most
-			  once.
-		Optional properties:
-			* xlnx,bipolar: If set the channel is used in bipolar
-			  mode.
-
-
-Examples:
-	xadc@f8007100 {
-		compatible = "xlnx,zynq-xadc-1.00.a";
-		reg = <0xf8007100 0x20>;
-		interrupts = <0 7 4>;
-		interrupt-parent = <&gic>;
-		clocks = <&pcap_clk>;
-
-		xlnx,channels {
-			#address-cells = <1>;
-			#size-cells = <0>;
-			channel@0 {
-				reg = <0>;
-			};
-			channel@1 {
-				reg = <1>;
-			};
-			channel@8 {
-				reg = <8>;
-			};
-		};
-	};
-
-	xadc@43200000 {
-		compatible = "xlnx,axi-xadc-1.00.a";
-		reg = <0x43200000 0x1000>;
-		interrupts = <0 53 4>;
-		interrupt-parent = <&gic>;
-		clocks = <&fpga1_clk>;
-
-		xlnx,channels {
-			#address-cells = <1>;
-			#size-cells = <0>;
-			channel@0 {
-				reg = <0>;
-				xlnx,bipolar;
-			};
-		};
-	};
-
-	adc@80000000 {
-		compatible = "xlnx,system-management-wiz-1.3";
-		reg = <0x80000000 0x1000>;
-		interrupts = <0 81 4>;
-		interrupt-parent = <&gic>;
-		clocks = <&fpga1_clk>;
-
-		xlnx,channels {
-			#address-cells = <1>;
-			#size-cells = <0>;
-			channel@0 {
-				reg = <0>;
-				xlnx,bipolar;
-			};
-		};
-	};
diff --git a/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.yaml b/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.yaml
new file mode 100644
index 000000000000..17508fef1f43
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.yaml
Filename matching compatible, e.g. xlnx,axi-xadc.yaml

quoted hunk ↗ jump to hunk
@@ -0,0 +1,194 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/xilinx-xadc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Xilinx XADC and System Monitor ADC
+
+description:
+  The Xilinx XADC is an ADC that can be found in the Series 7 FPGAs from Xilinx.
+  The XADC has a DRP interface for communication. Currently two different
+  frontends for the DRP interface exist. One that is only available on the ZYNQ
+  family as a hardmacro in the SoC portion of the ZYNQ. The other one is available
+  on all series 7 platforms and is a softmacro with an AXI interface.
+
+  The Xilinx System Monitor is an ADC that is found in the UltraScale and
+  UltraScale+ FPGAs from Xilinx. The System Monitor provides a DRP interface for
+  communication. Xilinx provides a standard IP core that can be used to access the
+  System Monitor through an AXI interface in the FPGA fabric. This IP core is
+  called the Xilinx System Management Wizard.
+
+  The System Management Wizard can also be accessed via I2C interface for remote
+  monitoring scenarios where the system Management Wizard is located on a different chip.
Not wrapped correctly. Please read coding style.
+
+maintainers:
+  - Lars-Peter Clausen [off-list ref]
+  - Sai Krishna Potthuri [off-list ref]
+
+properties:
+  compatible:
+    enum:
+      - xlnx,zynq-xadc-1.00.a
+      - xlnx,axi-xadc-1.00.a
+      - xlnx,system-management-wiz-1.3
+      - xlnx,system-management-wiz-1.3-remote
There was no such compatible and nothing explains why it appeared. You
cannot just add new ABI and claim it is just a conversion.
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+    description:
+      When using the ZYNQ this must be the ZYNQ PCAP clock,
+      when using the axi-xadc or the axi-system-management-wizard this must be
+      the clock that provides the clock to the AXI bus interface of the core.
+
+  xlnx,external-mux:
+    $ref: /schemas/types.yaml#/definitions/string
+    enum:
+      - none
+      - single
+      - dual
+    default: none
+    description: |
+      External multiplexer configuration:
+      - "none": No external multiplexer is used (default)
Drop "default", don't repeat constraints in free form text.
+      - "single": External multiplexer mode is used with one multiplexer
+      - "dual": External multiplexer mode is used with two multiplexers
+        for simultaneous sampling
+
+  xlnx,external-mux-channel:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 16
+    description: |
+      Configures which pair of pins is used to sample data in external mux mode.
+      Valid values for single external multiplexer mode are 0-16:
+      0: VP/VN
+      1-16: VAUXP[0-15]/VAUXN[0-15]
+      Valid values for dual external multiplexer mode are 1-8:
+      1-8: VAUXP[0-7]/VAUXN[0-7] - VAUXP[8-15]/VAUXN[8-15]
+      This property needs to be present if the device is configured for
+      external multiplexer mode (either single or dual).
+
+  xlnx,channels:
+    $ref: '#/$defs/channels'
+
+allOf:
Missing ref since you use unevaluatedProperties...
+  - if:
+      required:
+        - xlnx,external-mux
+      properties:
+        xlnx,external-mux:
+          enum:
+            - single
+            - dual
+    then:
+      required:
+        - xlnx,external-mux-channel
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
or you meant additionalProperties?
+
+$defs:
Why this is a def, not used directly? I see only one usage of this def.
+  channels:
+    type: object
+    description: List of external channels that are connected to the ADC
+    properties:
+      '#address-cells':
+        const: 1
+      '#size-cells':
+        const: 0
+
+    patternProperties:
+      "^channel@([0-9]|1[0-6])$":
+        type: object
+        properties:
+          reg:
+            minimum: 0
+            maximum: 16
+            description: |
+              Pair of pins the channel is connected to:
+                0: VP/VN
+                1-16: VAUXP[0-15]/VAUXN[0-15]
+              Note each channel number should only be used at most once.
+
+          xlnx,bipolar:
+            type: boolean
+            description: If set, the channel is used in bipolar mode
+
+        required:
+          - reg
+
+        unevaluatedProperties: false
Again, where is any $ref?
+
+    required:
+      - '#address-cells'
+      - '#size-cells'
+
+    unevaluatedProperties: false
And here, please read writing schema and writing bindings docs.
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    xadc@f8007100 {
adc

Node names should be generic. See also an explanation and list of
examples (not exhaustive) in DT specification:
https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation
If you cannot find a name matching your device, please check in kernel
sources for similar cases or you can grow the spec (via pull request to
DT spec repo).
+        compatible = "xlnx,zynq-xadc-1.00.a";
+        reg = <0xf8007100 0x20>;
+        interrupts = <0 7 4>;
Use proper defines.
+        clocks = <&pcap_clk>;
+
+        xlnx,channels {
+            #address-cells = <1>;
+            #size-cells = <0>;
+            channel@0 {
+                reg = <0>;
+            };
+            channel@1 {
+                reg = <1>;
+            };
+            channel@8 {
+                reg = <8>;
+            };
+        };
+    };
+
+  - |
+    xadc@43200000 {
One example is enough, I don't see differences here.
+        compatible = "xlnx,axi-xadc-1.00.a";
+        reg = <0x43200000 0x1000>;
+        interrupts = <0 53 4>;
+        clocks = <&fpga1_clk>;
+
+        xlnx,channels {
+            #address-cells = <1>;
+            #size-cells = <0>;
+            channel@0 {
+                reg = <0>;
+                xlnx,bipolar;
+            };
+        };
+    };
+
+  - |
+    adc@80000000 {
Again, one example is enough, unless you have multiple differences in
properties.

Best regards,
Krzysztof

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