scripts/liberty: Accept target output file as argument

Instead of giving the library and corner to gnerate, you can provide
the target .lib file you want generated and this will pick the right
parameters to generate that file

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

scripts/python-skywater-pdk/skywater_pdk/liberty.py

@@ -194,6 +194,36 @@ def top_corner_file(libname, corner, corner_type: TimingType, directory_prefix =
           corner_type=corner_type.file)
 
 
+def top_liberty_file(libname, corner, corner_type: TimingType, directory_prefix = "timing"):
+    """
+
+    >>> top_liberty_file("sky130_fd_sc_hd", "ff_100C_1v65", TimingType.ccsnoise)
+    'timing/sky130_fd_sc_hd__ff_100C_1v65_ccsnoise.lib'
+    >>> top_liberty_file("sky130_fd_sc_hd", "ff_100C_1v65", TimingType.basic)
+    'timing/sky130_fd_sc_hd__ff_100C_1v65.lib'
+    >>> top_liberty_file("sky130_fd_sc_hd", "ff_100C_1v65", TimingType.basic, "")
+    'sky130_fd_sc_hd__ff_100C_1v65.lib'
+
+    """
+    return top_corner_file(libname, corner, corner_type, directory_prefix).replace('.lib.json', '.lib')
+
+
+def top_liberty_file_split(fname):
+    """
+    Splits a fully specified top liberty file name into library / corner / corner_type
+
+    >>> top_liberty_file_split('timing/sky130_fd_sc_hd__ff_100C_1v65_ccsnoise.lib')
+    ('sky130_fd_sc_hd', 'ff_100C_1v65', <TimingType.ccsnoise: 3>)
+    >>> top_liberty_file_split('timing/sky130_fd_sc_hd__ff_100C_1v65.lib')
+    ('sky130_fd_sc_hd', 'ff_100C_1v65', <TimingType.basic: 1>)
+
+    """
+    m = re.match('(.*)__(.*)\.lib', os.path.basename(fname))
+    if m is None:
+        return None
+    return ( m.group(1), *TimingType.parse(m.group(2)) )
+
+
 def collect(library_dir) -> Tuple[Dict[str, TimingType], List[str]]:
     """Collect the available timing information in corners.
 
@@ -337,7 +367,7 @@ remove_ccsnoise_from_library = remove_ccsnoise_from_dict
 
 def generate(library_dir, lib, corner, ocorner_type, icorner_type, cells, output_directory):
     output_directory_prefix = None if output_directory else "timing"
-    top_fname = top_corner_file(lib, corner, ocorner_type, output_directory_prefix).replace('.lib.json', '.lib')
+    top_fname = top_liberty_file(lib, corner, ocorner_type, output_directory_prefix)
     output_directory = output_directory if output_directory else library_dir
     top_fpath = os.path.join(output_directory, top_fname)
 
@@ -1133,14 +1163,28 @@ def main():
 
     retcode = 0
 
-    lib, corners, all_cells = collect(libdir)
+    if libdir.is_dir():
+        # libdir is a directory, collect available corners and process specified ones
+        if args.ccsnoise:
+            output_corner_type = TimingType.ccsnoise
+        elif args.leakage:
+            output_corner_type = TimingType.leakage
+        else:
+            output_corner_type = TimingType.basic
+
+    elif libdir.suffix == '.lib':
+        # libdir is directly the liberty target file to generate, derive params from it
+        s = top_liberty_file_split(libdir.name)
+
+        libdir = libdir.parents[1]
+        args.corner = [ s[1] ]
+        output_corner_type = s[2]
 
-    if args.ccsnoise:
-        output_corner_type = TimingType.ccsnoise
-    elif args.leakage:
-        output_corner_type = TimingType.leakage
     else:
-        output_corner_type = TimingType.basic
+        msg_err("Invalid library path (neither source directory or liberty library target")
+        return 1
+
+    lib, corners, all_cells = collect(libdir)
 
     if args.corner == ['all']:
         args.corner = list(sorted(k for k, (v0, v1) in corners.items() if output_corner_type in v0))