[PATCH i-g-t v2 3/6] tools/intel-gfx-fw-info: Embed fw decoding

[Lucas De Marchi <lucas.demarchi@intel.com>]

Use a factory class method to decide what class to use depending on the
magic and embed the calls to cstruct in each of them. Main motivation is
that in future the decode method will need to seek the binary as it
can't really know the version just checking the beginning of the file.

For now, keep the open/close of the file in the main function, but
eventually can be migrated as well.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
---
 tools/intel-gfx-fw-info | 73 ++++++++++++++++++++++++++++-------------
 1 file changed, 51 insertions(+), 22 deletions(-)

diff --git a/tools/intel-gfx-fw-info b/tools/intel-gfx-fw-info
index 3105144b7..0f1da8bff 100755
--- a/tools/intel-gfx-fw-info
+++ b/tools/intel-gfx-fw-info
@@ -105,8 +105,38 @@ def FIELD_GET(mask: int, value: int) -> int:
 
 
 class Fw(abc.ABC):
-    def __init__(self, fw):
-        self.fw = fw
+    def __init__(self, cparser, f):
+        self.f = f
+        self.cparser = cparser
+        self.fw = None
+
+    def checksum(self):
+        self.f.seek(0, 0)
+        return hashlib.sha256(self.f.read()).hexdigest()
+
+    def dump(self, **kw):
+        cstruct.dumpstruct(self.fw, kw)
+
+    @classmethod
+    def create(cls, f):
+        cparser = cstruct.cstruct()
+        cparser.load(CDEF)
+
+        magic = cparser.magic(f).data
+        default = None
+
+        for s in cls.__subclasses__():
+            if s.MAGIC is None:
+                default = s
+            elif s.MAGIC == magic:
+                f.seek(0, 0)
+                return s(cparser, f)
+
+        if default:
+            f.seek(0, 0)
+            return default(cparser, f)
+
+        return None
 
     @abc.abstractmethod
     def decode(self):
@@ -114,8 +144,13 @@ class Fw(abc.ABC):
 
 
 class FwCss(Fw):
+    MAGIC = None
+
     def decode(self):
-        data = []
+        self.f.seek(0, 0)
+        self.fw = self.cparser.uc_css_header(self.f)
+
+        data = ["header-type: CSS"]
 
         CSS_SW_VERSION_UC_MAJOR = 0xFF << 16
         CSS_SW_VERSION_UC_MINOR = 0xFF << 8
@@ -137,8 +172,13 @@ class FwCss(Fw):
 
 
 class FwGsc(Fw):
+    MAGIC = b"$CPD"
+
     def decode(self):
-        data = []
+        self.f.seek(0, 0)
+        self.fw = self.cparser.uc_huc_gsc_header(self.f)
+
+        data = ["header-type: GSC"]
 
         HUC_GSC_MINOR_VER_HI_MASK = 0xFF << 16
         HUC_GSC_MAJOR_VER_HI_MASK = 0xFF
@@ -167,40 +207,29 @@ def parse_args(argv: typing.List[str]) -> argparse.Namespace:
     return parser.parse_args(argv)
 
 
-def calculate_checksum(f: typing.BinaryIO) -> str:
-    return hashlib.sha256(f.read()).hexdigest()
-
-
 def main(argv: typing.List[str]) -> int:
     args = parse_args(argv)
 
-    cparser = cstruct.cstruct()
-    cparser.load(CDEF)
-
     checksum = None
 
     try:
         with open(args.filename, mode="rb") as f:
-            magic = cparser.magic(f)
-            f.seek(0, 0)
-            if magic.data == b"$CPD":
-                fw = FwGsc(cparser.uc_huc_gsc_header(f))
-            else:
-                fw = FwCss(cparser.uc_css_header(f))
+            fw = Fw.create(f)
+            if not fw:
+                logging.fatal("Unknown firmware type in '{args.filename}'")
 
+            decoded_data = fw.decode()
             if args.checksum:
-                f.seek(0, 0)
-                checksum = calculate_checksum(f)
-
+                checksum = fw.checksum()
     except FileNotFoundError as e:
         logging.fatal(e)
         return 1
 
-    print(*fw.decode(), sep="\n")
+    print(*decoded_data, sep="\n")
 
     if args.raw:
         print("raw dump:", end="")
-        cstruct.dumpstruct(fw.fw, color=sys.stdout.isatty())
+        fw.dump(color=sys.stdout.isatty())
 
     if checksum:
         print(f"checksum: {checksum}")
-- 
2.43.0