1 files changed, 49 insertions, 0 deletions
diff --git a/board/cr50/tpm2/trng.c b/board/cr50/tpm2/trng.c
index 7cce13ff1c..ae4312be2c 100644
--- a/board/cr50/tpm2/trng.c
+++ b/board/cr50/tpm2/trng.c
@@ -9,3 +9,52 @@ CRYPT_RESULT _cpri__StirRandom(int32_t num, uint8_t *entropy)
 {
 	return CRYPT_SUCCESS;     /* NO-OP on CR50. */
 }
+
+#ifdef CRYPTO_TEST_SETUP
+#include "endian.h"
+#include "extension.h"
+#include "trng.h"
+/*
+ * This extension command is similar to TPM2_GetRandom, but made
+ * available for CRYPTO_TEST = 1 which disables TPM.
+ * Command structure, shared out of band with the test driver running
+ * on the host:
+ *
+ * field     |    size  |                  note
+ * =========================================================================
+ * text_len  |    2     | the number of random bytes to generate, big endian
+ * type      |    1     | 0 = TRNG, other values reserved for extensions
+ */
+static enum vendor_cmd_rc trng_test(enum vendor_cmd_cc code, void *buf,
+				    size_t input_size, size_t *response_size)
+{
+	uint16_t text_len;
+	uint8_t *cmd = buf;
+	uint8_t op_type = 0;
+
+	if (input_size != sizeof(text_len) + 1) {
+		*response_size = 0;
+		return VENDOR_RC_BOGUS_ARGS;
+	}
+
+	text_len = be16toh(*(uint16_t *)cmd);
+	op_type = cmd[sizeof(text_len)];
+
+	if (text_len > *response_size) {
+		*response_size = 0;
+		return VENDOR_RC_BOGUS_ARGS;
+	}
+
+	switch (op_type) {
+	case 0:
+		rand_bytes(buf, text_len);
+		break;
+	default:
+		return VENDOR_RC_BOGUS_ARGS;
+	}
+	*response_size = text_len;
+	return VENDOR_RC_SUCCESS;
+}
+
+DECLARE_VENDOR_COMMAND(VENDOR_CC_TRNG_TEST, trng_test);
+#endif /* CRYPTO_TEST_SETUP */