feat: enhance core-STA integration and timing analysis

- Updated soc_topology.json to include new fabric links for core, DMA, native, and APB interfaces.
- Refactored retrosoc.sv to utilize generated fabric links and included necessary SVH files for better modularity.
- Improved check_clock_reset_domains.py to validate hierarchical pins and added support for positive number checks.
- Modified regress.py to include OpenSTA in the regression commands.
- Enhanced README.md in the STA directory to clarify the timing analysis flow and supported PDK profiles.
- Removed outdated gen2.sdc file and replaced it with a dynamic SDC generation approach.
- Updated opensta.mk to generate SDC files dynamically based on the current domain map and pin map.
- Created generate_sdc.py to automate SDC generation from clock/reset domain inventory.
- Added tests for generated core-STA constraints to ensure coverage of current clock domains and validate pin map integrity.
- Introduced new timing metrics and warnings for the sky130 PDK in the quality checks.

tests/test_sta_constraints.py

@@ -0,0 +1,115 @@
+"""Tests for generated core-STA constraints."""
+
+from __future__ import annotations
+
+import json
+import subprocess
+import sys
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+DOMAINS = ROOT / "rtl/mini/integration/clock_reset_domains.json"
+PIN_MAP = ROOT / "rtl/mini/pin_map/pin_map.json"
+GENERATOR = ROOT / "sta/opensta/generate_sdc.py"
+GF180_GENERATOR = ROOT / "pdk/generate_gf180_liberty.py"
+
+
+def generate(domains: Path, output: Path) -> subprocess.CompletedProcess[str]:
+    return subprocess.run(
+        [
+            sys.executable,
+            str(GENERATOR),
+            "--domains",
+            str(domains),
+            "--pin-map",
+            str(PIN_MAP),
+            "--output",
+            str(output),
+        ],
+        text=True,
+        capture_output=True,
+    )
+
+
+def test_core_sdc_covers_current_clock_domains(tmp_path: Path) -> None:
+    output = tmp_path / "retrosoc_core.sdc"
+    result = generate(DOMAINS, output)
+
+    assert result.returncode == 0, result.stderr
+    sdc = output.read_text(encoding="utf-8")
+    assert "create_clock -name clk_external -period 13.888888889" in sdc
+    assert "create_generated_clock -name clk_system" in sdc
+    assert "create_clock -name clk_audio -period 54.253472222" in sdc
+    assert "create_clock -name clk_dvp -period 41.666666667" in sdc
+    assert "u_dvp_pclk_clk_buf/clk_o" in sdc
+    assert "-group [get_clocks {clk_external clk_system}]" in sdc
+    assert "set_clock_transition 0.1 [get_clocks {clk_dvp}]" in sdc
+    assert "set_input_transition" not in sdc
+    assert "set_false_path -from $reset_ext_rst_n_i_pad" in sdc
+
+
+def test_core_sdc_rejects_pads_missing_from_the_pin_map(tmp_path: Path) -> None:
+    document = json.loads(DOMAINS.read_text(encoding="utf-8"))
+    document["domains"][3]["sta"]["source_port"] = "missing_pad"
+    invalid = tmp_path / "clock_reset_domains.json"
+    invalid.write_text(json.dumps(document), encoding="utf-8")
+
+    result = generate(invalid, tmp_path / "retrosoc_core.sdc")
+
+    assert result.returncode != 0
+    assert "source port is not declared in pin map" in result.stderr
+
+
+def test_gf180_liberty_generator_assembles_requested_io_cells(tmp_path: Path) -> None:
+    library = "gf180mcu_fd_io"
+    corner = "ss_125C_4v50"
+    source = tmp_path / "source"
+    library_dir = source / "libraries" / library / "latest"
+    liberty_dir = library_dir / "liberty"
+    cells_dir = library_dir / "cells"
+    liberty_dir.mkdir(parents=True)
+    (liberty_dir / f"{library}__{corner}.lib").write_text(
+        "library (gf180_io) {\n}\n", encoding="utf-8"
+    )
+    for cell in ("bi_t", "in_c"):
+        cell_dir = cells_dir / cell
+        cell_dir.mkdir(parents=True)
+        (cell_dir / f"{library}__{cell}__{corner}.lib").write_text(
+            f"cell ({cell}) {{}}\n", encoding="utf-8"
+        )
+
+    output_dir = tmp_path / "output"
+    result = subprocess.run(
+        [
+            sys.executable,
+            str(GF180_GENERATOR),
+            "--source",
+            str(source),
+            "--output-dir",
+            str(output_dir),
+            "--revision",
+            "locked-revision",
+            "--library",
+            library,
+            "--cell",
+            "bi_t",
+            "--cell",
+            "in_c",
+            "--corner",
+            corner,
+            "--output-name",
+            "retrosoc_io.lib",
+        ],
+        text=True,
+        capture_output=True,
+    )
+
+    assert result.returncode == 0, result.stderr
+    output = output_dir / "retrosoc_io.lib"
+    assert "library (gf180_io)" in output.read_text(encoding="utf-8")
+    assert "cell (bi_t) {}" in output.read_text(encoding="utf-8")
+    assert "cell (in_c) {}" in output.read_text(encoding="utf-8")
+    assert (output.with_suffix(".lib.revision")).read_text(encoding="utf-8") == (
+        "locked-revision\ngf180mcu_fd_io\nbi_t,in_c\n"
+    )