interconnect: add DM test suite

Add a test suite exercising the whole lifetime and callbacks
of interconnect with a fake 5 providers with a split node graph.

The test suite checks the calculus are right and goes to the correct
nodes, and the lifetime of the node is correct.

Link: https://patch.msgid.link/[email protected]
Signed-off-by: Neil Armstrong <[email protected]>

2 files changed, 55 insertions, 0 deletions

diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
index 13d8e498b03..0b3fc505e53 100644
--- a/arch/sandbox/dts/test.dts
+++ b/arch/sandbox/dts/test.dts
@@ -864,6 +864,42 @@
 		};
 	};
 
+	icc0: interconnect-0 {
+		compatible = "sandbox,interconnect0";
+		#interconnect-cells = <1>;
+	};
+
+	icc1: interconnect-1 {
+		compatible = "sandbox,interconnect1";
+		#interconnect-cells = <1>;
+	};
+
+	icc2: interconnect-2 {
+		compatible = "sandbox,interconnect2";
+		#interconnect-cells = <1>;
+	};
+
+	icc3: interconnect-3 {
+		compatible = "sandbox,interconnect3";
+		#interconnect-cells = <1>;
+	};
+
+	icc4: interconnect-4 {
+		compatible = "sandbox,interconnect4";
+		#interconnect-cells = <1>;
+	};
+
+	interconnect-test-0 {
+		compatible = "sandbox,interconnect-test";
+		interconnects = <&icc0 0 &icc3 0>;
+	};
+
+	interconnect-test-1 {
+		compatible = "sandbox,interconnect-test";
+		interconnects = <&icc1 0 &icc4 0>;
+		interconnect-names = "icc-path";
+	};
+
 	i2c@0 {
 		#address-cells = <1>;
 		#size-cells = <0>;
diff --git a/arch/sandbox/include/asm/interconnect.h b/arch/sandbox/include/asm/interconnect.h
new file mode 100644
index 00000000000..17065bf6a11
--- /dev/null
+++ b/arch/sandbox/include/asm/interconnect.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2025 Linaro Limited
+ */
+
+#ifndef __SANDBOX_INTERCONNECT_H
+#define __SANDBOX_INTERCONNECT_H
+
+struct udevice;
+
+int sandbox_interconnect_get_bw(struct udevice *dev, u64 *avg, u64 *peak);
+int sandbox_interconnect_test_get(struct udevice *dev, char *name);
+int sandbox_interconnect_test_get_index(struct udevice *dev, int index);
+int sandbox_interconnect_test_enable(struct udevice *dev);
+int sandbox_interconnect_test_disable(struct udevice *dev);
+int sandbox_interconnect_test_set_bw(struct udevice *dev, u32 avg_bw, u32 peak_bw);
+int sandbox_interconnect_test_put(struct udevice *dev);
+
+#endif