1 files changed, 110 insertions, 0 deletions
diff --git a/chip/g/dcrypto/key_ladder.c b/chip/g/dcrypto/key_ladder.c
new file mode 100644
index 0000000000..d58b961f53
--- /dev/null
+++ b/chip/g/dcrypto/key_ladder.c
@@ -0,0 +1,110 @@
+/* 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 "dcrypto.h"
+#include "internal.h"
+#include "endian.h"
+#include "registers.h"
+
+void DCRYPTO_ladder_init(void)
+{
+	/* Do not reset keyladder engine here, as before.
+	 *
+	 * Should not be needed and if it is, it is indicative
+	 * of sync error between this and sha engine usage.
+	 * Reset will make this flow work, but will have broken
+	 * the other pending sha flow.
+	 * Hence leave as is and observe the error.
+	 *
+	 * TODO: hw sha engine usage and keyladder usage cannot
+	 * interleave and should share a semaphore.
+	 */
+}
+
+int DCRYPTO_ladder_step(uint32_t cert)
+{
+	uint32_t itop;
+
+	GREG32(KEYMGR, SHA_ITOP) = 0;  /* clear status */
+
+	GREG32(KEYMGR, SHA_USE_CERT_INDEX) =
+		(cert << GC_KEYMGR_SHA_USE_CERT_INDEX_LSB) |
+		GC_KEYMGR_SHA_USE_CERT_ENABLE_MASK;
+
+	GREG32(KEYMGR, SHA_CFG_EN) =
+		GC_KEYMGR_SHA_CFG_EN_INT_EN_DONE_MASK;
+	GREG32(KEYMGR, SHA_TRIG) =
+		GC_KEYMGR_SHA_TRIG_TRIG_GO_MASK;
+
+	do {
+		itop = GREG32(KEYMGR, SHA_ITOP);
+	} while (!itop);
+
+	GREG32(KEYMGR, SHA_ITOP) = 0;  /* clear status */
+
+	return !!GREG32(KEYMGR, HKEY_ERR_FLAGS);
+}
+
+static int compute_certs(const uint32_t *certs, size_t num_certs)
+{
+	int i;
+
+	for (i = 0; i < num_certs; i++) {
+		if (DCRYPTO_ladder_step(certs[i]))
+			return 0;
+	}
+
+	return 1;
+}
+
+#define KEYMGR_CERT_0 0
+#define KEYMGR_CERT_3 3
+#define KEYMGR_CERT_4 4
+#define KEYMGR_CERT_5 5
+#define KEYMGR_CERT_7 7
+#define KEYMGR_CERT_15 15
+#define KEYMGR_CERT_20 20
+#define KEYMGR_CERT_25 25
+#define KEYMGR_CERT_26 26
+
+static const uint32_t FRK2_CERTS_PREFIX[] = {
+	KEYMGR_CERT_0,
+	KEYMGR_CERT_3,
+	KEYMGR_CERT_4,
+	KEYMGR_CERT_5,
+	KEYMGR_CERT_7,
+	KEYMGR_CERT_15,
+	KEYMGR_CERT_20,
+};
+
+static const uint32_t FRK2_CERTS_POSTFIX[] = {
+	KEYMGR_CERT_26,
+};
+
+#define MAX_MAJOR_FW_VERSION 254
+
+int DCRYPTO_ladder_compute_frk2(size_t fw_version, uint8_t *frk2)
+{
+	int i;
+
+	if (fw_version > MAX_MAJOR_FW_VERSION)
+		return 0;
+
+	DCRYPTO_ladder_init();
+
+	if (!compute_certs(FRK2_CERTS_PREFIX, ARRAY_SIZE(FRK2_CERTS_PREFIX)))
+		return 0;
+
+	for (i = 0; i < MAX_MAJOR_FW_VERSION - fw_version; i++) {
+		if (DCRYPTO_ladder_step(KEYMGR_CERT_25))
+			return 0;
+	}
+
+	if (!compute_certs(FRK2_CERTS_POSTFIX, ARRAY_SIZE(FRK2_CERTS_POSTFIX)))
+		return 0;
+
+	memcpy(frk2, (void *) GREG32_ADDR(KEYMGR, HKEY_FRR0),
+		AES256_BLOCK_CIPHER_KEY_SIZE);
+	return 1;
+}