From b7c020c0dd6740a8bcbb022fb3469e3f69c95e25 Mon Sep 17 00:00:00 2001
From: Tim Trippel <ttrippel@google.com>
Date: Thu, 12 Dec 2024 14:43:08 -0800
Subject: [PATCH] [manuf] add delay to OTP writes

Allow charge pump to recover on real silicon.

Signed-off-by: Tim Trippel <ttrippel@google.com>
---
 sw/device/lib/testing/BUILD                | 1 +
 sw/device/lib/testing/otp_ctrl_testutils.c | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/sw/device/lib/testing/BUILD b/sw/device/lib/testing/BUILD
index b2f42b50813715..0e346b8d7e0e28 100644
--- a/sw/device/lib/testing/BUILD
+++ b/sw/device/lib/testing/BUILD
@@ -306,6 +306,7 @@ cc_library(
     target_compatible_with = [OPENTITAN_CPU],
     deps = [
         "//sw/device/lib/dif:otp_ctrl",
+        "//sw/device/lib/runtime:hart",
         "//sw/device/lib/runtime:ibex",
         "//sw/device/lib/runtime:log",
         "//sw/device/lib/testing/test_framework:check",
diff --git a/sw/device/lib/testing/otp_ctrl_testutils.c b/sw/device/lib/testing/otp_ctrl_testutils.c
index fda2322e4c8a08..86eb37654a625f 100644
--- a/sw/device/lib/testing/otp_ctrl_testutils.c
+++ b/sw/device/lib/testing/otp_ctrl_testutils.c
@@ -5,6 +5,7 @@
 #include "sw/device/lib/testing/otp_ctrl_testutils.h"
 
 #include "sw/device/lib/dif/dif_otp_ctrl.h"
+#include "sw/device/lib/runtime/hart.h"
 #include "sw/device/lib/runtime/ibex.h"
 #include "sw/device/lib/runtime/log.h"
 #include "sw/device/lib/testing/test_framework/check.h"
@@ -173,6 +174,9 @@ status_t otp_ctrl_testutils_dai_write32(const dif_otp_ctrl_t *otp,
     if (read_data != buffer[i]) {
       return INTERNAL();
     }
+
+    // Wait for charge pump to recover.
+    busy_spin_micros(10000);  // 10ms
   }
   return OK_STATUS();
 }
@@ -194,6 +198,9 @@ status_t otp_ctrl_testutils_dai_write64(const dif_otp_ctrl_t *otp,
     if (read_data != buffer[i]) {
       return INTERNAL();
     }
+
+    // Wait for charge pump to recover.
+    busy_spin_micros(10000);  // 10ms
   }
   return OK_STATUS();
 }