[ot] scripts/opentitan: cfggen.py: Load OTP scrambling keys from SV

Parse the hard-coded OTP scrambling key constants out of the relevant SV
partition SV files into the generated OT configuration files, so that
they can be used in the OTP.

Signed-off-by: Alex Jones <[email protected]>

Author: AlexJones0

python/qemu/ot/otp/const.py

@@ -203,9 +203,16 @@ def get_digests(self) -> list[str]:
         except KeyError as exc:
             raise ValueError("No 'digest' enum found") from exc
 
+    def get_scrambling_keys(self) -> list[str]:
+        """Return a list of parsed scrambling keys for secret partitions."""
+        try:
+            return list(self._enums['key'])
+        except KeyError as exc:
+            raise ValueError("No 'key' enum found") from exc
+
     def get_digest_pair(self, name: str, prefix: str) -> dict[str, str]:
         """Return a dict of digest pair.
-           :param name: one of the enumerated values, see #get_enums
+           :param name: one of the enumerated values, see #get_digests
            :param prefix: the prefix to add to each dict key.
         """
         try:
@@ -221,6 +228,22 @@ def get_digest_pair(self, name: str, prefix: str) -> dict[str, str]:
                 odict[oname] = values[idx]
         return odict
 
+    def get_scrambling_key(self, name: str) -> str:
+        """Get the value of a scrambling key.
+           :param name: One of the enumerated values, see #get_scrambling_keys
+        """
+        try:
+            idx = self._enums['key'][name]
+        except KeyError as exc:
+            raise ValueError(f'Unknown scrambling key {name}') from exc
+        try:
+            key_values = self._consts['key']
+        except KeyError as exc:
+            raise ValueError('No scrambling key constants found') from exc
+        if len(key_values) <= idx:
+            raise ValueError(f'No such key {name} in the key array') from exc
+        return key_values[idx]
+
     def get_partition_inv_defaults(self, partition: int) -> Optional[str]:
         """Return the invalid default values for a partition, if any.
            Partitions with only digest defaults are considered without default

scripts/opentitan/cfggen.py

@@ -313,6 +313,10 @@ def prepare(self) -> None:
                 continue
             pair = self._otpconst.get_digest_pair(digest, prefix)
             otp_ctrl.update(pair)
+        for key in self._otpconst.get_scrambling_keys():
+            key_value = self._otpconst.get_scrambling_key(key)
+            key = key.removesuffix("key") + "_scramble_key"
+            otp_ctrl[key] = key_value
         idx = 0
         while True:
             try: