dtc: dt-check-style: Handle multiple blank lines in continued properties

Properly ignore comments and report duplicated blank lines in multi-line
properties.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Link: https://patch.msgid.link/20260911-dts-style-checker-blank-lines-v1-2-85e779600d98@oss.qualcomm.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

scripts/dtc/dt-check-style

@@ -440,6 +440,12 @@ def check_blank_lines(ctx):
         if lines[i].linetype == LineType.BLANK and \
                 lines[i - 1].linetype == LineType.BLANK:
             yield (lines[i].lineno, 'consecutive blank lines')
+        prev_is_blank = lines[i].linetype == LineType.BLANK
+        for cont in lines[i].continuations:
+            if cont.linetype == LineType.BLANK and prev_is_blank:
+                yield (cont.lineno, 'consecutive blank lines')
+            prev_is_blank = cont.linetype == LineType.BLANK
+
     # Blank right after { or right before }
     for i, dl in enumerate(lines):
         if dl.linetype != LineType.BLANK:

scripts/dtc/dt-style-selftest/bad/dts-blank-lines.dts

@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+/dts-v1/;
+
+/ {
+	compatible = "example,test-board";
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	interrupt-controller@10000 {
+		compatible = "example,intc";
+
+		reg = <0x10000 0x1000>;
+
+		clocks = <1 2 3>,
+
+
+			 /* Comment is not a blank line */
+			 <4 5 6>,
+
+			 /* Comment is not a blank line */
+			 <7 8 9>;
+
+
+		interrupts = <1>;
+
+		/* Comment is not a blank line */
+		qcom,calibration-variant = "foo";
+	};
+
+
+	interrupt-controller@20000 {
+
+		compatible = "example,intc";
+		reg = <0x20000 0x1000>;
+
+	};
+};

scripts/dtc/dt-style-selftest/bad/yaml-blank-lines.yaml

@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/test-bad-blank-lines.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Test fixture with too many blank lines
+
+maintainers:
+  - Test User <test@example.com>
+
+properties:
+  compatible:
+    const: example,test-blank-lines
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    foo@1000 {
+        compatible = "example,test-blank-lines";
+
+        reg = <0x1000 0x100>;
+
+        clocks = <1 2 3>,
+
+
+                 /* Comment is not a blank line */
+                 <4 5 6>,
+
+                 /* Comment is not a blank line */
+                 <7 8 9>;
+
+
+        interrupts = <1>;
+
+        /* Comment is not a blank line */
+        qcom,calibration-variant = "foo";
+    };
+
+
+    foo@2000 {
+
+        compatible = "example,test-blank-lines";
+
+        reg = <0x2000 0x100>;
+
+    };

scripts/dtc/dt-style-selftest/expected/dts-blank-lines.dts.txt

@@ -0,0 +1,6 @@
+# mode=strict
+bad/dts-blank-lines.dts:16: [blank-lines] consecutive blank lines
+bad/dts-blank-lines.dts:23: [blank-lines] consecutive blank lines
+bad/dts-blank-lines.dts:30: [blank-lines] consecutive blank lines
+bad/dts-blank-lines.dts:32: [blank-lines] blank line at start of node body
+bad/dts-blank-lines.dts:35: [blank-lines] blank line at end of node body

scripts/dtc/dt-style-selftest/expected/yaml-blank-lines.yaml.txt

@@ -0,0 +1,6 @@
+# mode=strict
+bad/yaml-blank-lines.yaml:33: example 0 [blank-lines] consecutive blank lines
+bad/yaml-blank-lines.yaml:40: example 0 [blank-lines] consecutive blank lines
+bad/yaml-blank-lines.yaml:47: example 0 [blank-lines] consecutive blank lines
+bad/yaml-blank-lines.yaml:49: example 0 [blank-lines] blank line at start of node body
+bad/yaml-blank-lines.yaml:53: example 0 [blank-lines] blank line at end of node body