Add new tools/topo2_list_vol_kcontrols.py

Will be used in next commit to fix thesofproject#1068. See also discussion in earlier
attempt thesofproject#1068.

tools/topo2_list_vol_kcontrols.py

@@ -0,0 +1,58 @@
+#!/usr/bin/env python3
+
+"""Parses the .tplg file argument and returns a list of volume
+kcontrols, one per line.
+
+Pro tip: try using these commands _interactively_ with ipython3
+"""
+
+# Keep this script short and simple. If you want to get something else
+# from .tplg files, create another script.
+
+import sys
+from tplgtool2 import TplgBinaryFormat, TplgType, DapmType
+
+TPLG_FORMAT = TplgBinaryFormat()
+
+
+def main():
+    "Main"
+
+    parsed_tplg = TPLG_FORMAT.parse_file(sys.argv[1])
+
+    # pylint: disable=invalid-name
+    DAPMs = [
+        item for item in parsed_tplg if item.header.type == TplgType.DAPM_WIDGET.name
+    ]
+
+    for dapm in DAPMs:
+
+        gain_blocks = [b for b in dapm.blocks if b.widget.id == DapmType.PGA.name]
+
+        for gb in gain_blocks:
+            # debug
+            # print(f"{gb.widget.id}: {gb.widget.name}")
+
+            # Either 1 volume kcontrol, or 1 volume + 1 switch
+            assert gb.widget.num_kcontrols > 0
+
+            # A switch is either a DapmType.SWITCH, or DapmType.MIXER
+            # with a max = 1. Exclude switches.
+            volume_kcontrols = [
+                kc
+                for kc in gb.kcontrols
+                if kc.hdr.type == DapmType.MIXER.name and kc.body.max != 1
+            ]
+
+            assert len(volume_kcontrols) == 1
+
+            # TODO: find how the kernel makes this "topology v1 versus v2"
+            # decision and mimic it here.
+            pga_prefix = f"{gb.widget.name} " if gb.widget.name.startswith("PGA") else ""
+
+            for vkc in volume_kcontrols:
+                print(pga_prefix + vkc.hdr.name)
+
+
+if __name__ == "__main__":
+    main()