vboot: Add vboot for EC by EC

This patch adds vboot for EC by EC (vboot EC) for x86 systems.
When ec is transitioning s5->s3, it checks the power supply is
enough to boot AP or not. If not, it runs other checks and may
finally validate and jump to a RW image.

BUG=b:38462249
BRANCH=none
TEST=Boot Fizz on barrel jack and type-c charger.

Change-Id: I5988b0595976370c5303c45541702ae89d86fc97
Reviewed-on: https://chromium-review.googlesource.com/518254
Commit-Ready: Daisuke Nojiri <dnojiri@chromium.org>
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>

include/usb_pd.h

@@ -1494,6 +1494,13 @@ void pd_hw_init_rx(int port);
  */
 int pd_analyze_rx(int port, uint32_t *payload);
 
+/**
+ * Check if PD communication is enabled
+ *
+ * @return true if it's enabled or false otherwise
+ */
+int pd_comm_is_enabled(int port);
+
 /**
  * Get connected state
  *

include/vboot.h

@@ -0,0 +1,15 @@
+/* Copyright 2017 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.
+ */
+
+/**
+ * Verify RW image and jump to it
+ *
+ * Calling this API results in one of the followings:
+ * 1. Returns, expecting PD will provide enough power after negotiation
+ * 2. Jumps to RW (no return)
+ * 3. Returns, requesting more power
+ * 4. Returns, requesting recovery
+ */
+void vboot_ec(void);