docs: add licensing information and attribution comments to various RTL and test files

- Updated multiple RTL files in the  and  directories to include licensing information under the Mulan PSL v2.
- Added attribution comments for contributions from ETH Zurich and University of Bologna in .
- Enhanced test files in the  directory with licensing details and ensured compliance with the Solderpad Hardware License, Version 0.51.
- Introduced a new test in  to verify the preservation of attribution for PULP HyperBus sources.

tests/test_opipsram.py

@@ -21,6 +21,34 @@ HAL_REGS = ROOT / "crt/include/retrosoc/hal/opipsram_regs.h"
 HAL_SOURCE = ROOT / "crt/src/hal/opipsram.c"
 OPIPSRAM_MODEL = ROOT / "rtl/mini/dv/model/opipsram_model.sv"
 OPIPSRAM_TB = ROOT / "tests/rtl/opipsram_tb.sv"
+PULP_HYPERBUS_COMMIT = "80de8df600edc5d7956a94c9d42f911d6e61efd7"
+PULP_SHL_LICENSE = ROOT / "licenses/PULP_Platform-SHL-0.51"
+PULP_PHY_SOURCES = {
+    ROOT / "rtl/ip/memory/opipsram_phy.sv": (
+        "src/hyperbus_phy.sv",
+        (
+            "Armin Berger <bergerar@ethz.ch>",
+            "Stephan Keck <kecks@ethz.ch>",
+            "Thomas Benz <tbenz@iis.ee.ethz.ch>",
+            "Paul Scheffler <paulsc@iis.ee.ethz.ch>",
+        ),
+    ),
+    ROOT / "rtl/ip/memory/opipsram_trx.sv": (
+        "src/hyperbus_trx.sv",
+        (
+            "Paul Scheffler <paulsc@iis.ee.ethz.ch>",
+            "Armin Berger <bergerar@ethz.ch>",
+            "Stephan Keck <kecks@ethz.ch>",
+        ),
+    ),
+    ROOT / "rtl/tech/tc_opipsram_delay.sv": (
+        "src/hyperbus_delay.sv",
+        (
+            "Thomas Benz <paulsc@iis.ee.ethz.ch>",
+            "Paul Scheffler <paulsc@iis.ee.ethz.ch>",
+        ),
+    ),
+}
 
 
 def _values(path: Path, pattern: str) -> dict[str, int]:
@@ -39,6 +67,29 @@ def _values(path: Path, pattern: str) -> dict[str, int]:
     return values
 
 
+def test_opipsram_phy_preserves_pulp_hyperbus_attribution() -> None:
+    assert PULP_SHL_LICENSE.is_file()
+    license_text = PULP_SHL_LICENSE.read_text(encoding="utf-8")
+    assert "SOLDERPAD HARDWARE LICENSE version 0.51" in license_text
+
+    for path, (source, authors) in PULP_PHY_SOURCES.items():
+        text = path.read_text(encoding="utf-8")
+        assert text.startswith("// Copyright 2023 ETH Zurich and University of Bologna.\n")
+        assert "// Solderpad Hardware License, Version 0.51, see LICENSE for details.\n" in text
+        assert "// SPDX-License-Identifier: SHL-0.51\n" in text
+        assert f"PULP Platform HyperBus v0.0.4 ({source})" in text
+        assert PULP_HYPERBUS_COMMIT in text
+        assert "Modified by retroSoC" in text
+        assert "retroSoC is licensed under Mulan PSL v2." in text
+        for author in authors:
+            assert f"// {author}\n" in text
+
+    for path in (ROOT / "docs/ip/opipsram.md", ROOT / "ATTRIBUTIONS.md", ROOT / "NOTICE"):
+        text = path.read_text(encoding="utf-8")
+        assert PULP_HYPERBUS_COMMIT in text
+        assert "SHL-0.51" in text
+
+
 def test_opipsram_protocol_model_compiles_and_runs() -> None:
     verilator = shutil.which("verilator")
     if verilator is None: