CR50: implement _cpri__StirRandom as a no-op.

Stirring the random pool on CR50 is not currently
supported, so just implement as a no-op.

TEST=none
BRANCH=none
BUG=chrome-os-partner:43025,chrome-os-partner:47524

Change-Id: I32b0144737139e524d4f71a11cc9d4ad939cd9cb
Signed-off-by: nagendra modadugu <ngm@google.com>
Reviewed-on: https://chromium-review.googlesource.com/324620
Commit-Ready: Nagendra Modadugu <ngm@google.com>
Tested-by: Nagendra Modadugu <ngm@google.com>
Reviewed-by: Bill Richardson <wfrichar@chromium.org>

3 files changed, 12 insertions, 8 deletions

diff --git a/board/cr50/build.mk b/board/cr50/build.mk
index c2efe7e907..67a2e94eff 100644
--- a/board/cr50/build.mk
+++ b/board/cr50/build.mk
@@ -36,6 +36,7 @@ board-y += tpm2/hash_data.o
 board-y += tpm2/platform.o
 board-y += tpm2/rsa.o
 board-y += tpm2/stubs.o
+board-y += tpm2/trng.o
 
 # Build and link with an external library
 EXTLIB := $(realpath ../../third_party/tpm2)
diff --git a/board/cr50/tpm2/stubs.c b/board/cr50/tpm2/stubs.c
index 3583a466e9..37259d49fd 100644
--- a/board/cr50/tpm2/stubs.c
+++ b/board/cr50/tpm2/stubs.c
@@ -145,14 +145,6 @@ BOOL _cpri__Startup(
   return 1;
 }
 
-CRYPT_RESULT _cpri__StirRandom(
-  INT32 entropySize,
-  BYTE * entropy)
-{
-  ecprintf("%s called\n", __func__);
-  return CRYPT_FAIL;
-}
-
 CRYPT_RESULT _cpri__TestKeyRSA(
   TPM2B * d,                    //   OUT: the address to receive the
   // private exponent
diff --git a/board/cr50/tpm2/trng.c b/board/cr50/tpm2/trng.c
new file mode 100644
index 0000000000..7cce13ff1c
--- /dev/null
+++ b/board/cr50/tpm2/trng.c
@@ -0,0 +1,11 @@
+/* Copyright 2016 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "CryptoEngine.h"
+
+CRYPT_RESULT _cpri__StirRandom(int32_t num, uint8_t *entropy)
+{
+	return CRYPT_SUCCESS;     /* NO-OP on CR50. */
+}