[ot] hw/opentitan: ot_otp: make constant configurable at runtime

Signed-off-by: Emmanuel Blot <eblot@rivosinc.com>

Author: rivos-eblot

docs/opentitan/otcfg.md

@@ -20,7 +20,8 @@ Depending on the machine, the parameters may either override default constants d
 code - such as default cryptographic constants that are already exposed in the public OpenTitan
 repository - or be required in the configuration file for the matching device to become functional.
 
-Beware **not** to store such a configuration file into a public repository!
+⚠️ Beware **not** to store such a configuration file into a public repository if it contains
+   production data!
 
 ## Syntax
 
@@ -61,3 +62,29 @@ Constants can usually be retrieved from the OpenTitan autogenerated "top" HSJON
   nonce = "0123456789abcdef"
 ```
 where `<romid>` is the ROM identifier as documented [here](rom_ctrl.md#romid)
+
+### OTP controller [otp]
+
+```ini
+[ot_device "ot-otp-dj"]
+  # 256-bit scramble key, match RndCnstOtpCtrlScrmblKeyInit
+  scrmbl_key = "ffeeddccbbaa99887766554433221100ffeeddccbbaa99887766554433221100"
+  # consistency digest
+  digest_const = "ffeeddccbbaa99887766554433221100"
+  digest_iv = "0123456789abcdef"
+  # SRAM data key
+  sram_const = "ffeeddccbbaa99887766554433221100"
+  sram_iv = "0123456789abcdef"
+  # 20-byte sequence of the first non-RAW life cycle state (LC_STATE_TESTUNLOCKED0)
+  lc_state_first = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+  # 20-byte sequence of the last valid life cycle state (LC_STATE_SCRAP)
+  lc_state_last = "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
+  # 24-byte sequence for the first non-RAW transition count (#1)
+  lc_trscnt_first = "cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc"
+  # 24-byte sequence for the last transition count (#24)
+  lc_trscnt_last = "dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd"
+```
+
+Here, `digest_const` is expected to match the `--constant` argument of the [otptool.py](otptool.md)
+tool, whereas `digest_iv` is expected to match its `--iv` argument. Should those values differ,
+OpenTitan OTP controller would fail to verify the OTP partition digests.