Cr50: Add "wp" console command to control EC_WP_L

BUG=chrome-os-partner:49959
BRANCH=none
TEST=manual

On the Cr50 console, use the "wp" command to get/set the desired
state. On the EC console, use "gpioget wp_l" to watch it change.

Change-Id: I5978e6116ad0a07a7a61a8356dc1daf79e2397d0
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/373618
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>

board/cr50/build.mk

@@ -49,6 +49,7 @@ board-y += tpm2/rsa.o
 board-y += tpm2/stubs.o
 board-y += tpm2/trng.o
 board-y += tpm2/upgrade.o
+board-y += wp.o
 
 # Build and link with an external library
 EXTLIB := $(realpath ../../third_party/tpm2)

board/cr50/wp.c

@@ -0,0 +1,32 @@
+/* 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 "common.h"
+#include "console.h"
+#include "registers.h"
+
+static int command_wp(int argc, char **argv)
+{
+	int val;
+
+	if (argc > 1) {
+		if (!parse_bool(argv[1], &val))
+			return EC_ERROR_PARAM1;
+
+		/* Invert, because active low */
+		GREG32(RBOX, EC_WP_L) = !val;
+	}
+
+	/* Invert, because active low */
+	val = !GREG32(RBOX, EC_WP_L);
+
+	ccprintf("Flash WP is %s\n", val ? "enabled" : "disabled");
+
+	return EC_SUCCESS;
+}
+DECLARE_CONSOLE_COMMAND(wp, command_wp,
+	"[bool]",
+	"Get/set the flash HW write-protect signal",
+	NULL);