drivers/mrc_cache: move mrc_cache support to drivers

There's nothing intel-specific about the current mrc_cache support.
It's logic manages saving non-volatile areas into the boot media.
Therefore, expose it to the rest of the system for any and all to
use.

BUG=b:69614064

Change-Id: I3b331c82a102f88912a3e10507a70207fb20aecc
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/22901
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/include/mrc_cache.h

@@ -0,0 +1,43 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2014 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _COMMON_MRC_CACHE_H_
+#define _COMMON_MRC_CACHE_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+enum {
+	MRC_TRAINING_DATA,
+	MRC_VARIABLE_DATA,
+};
+
+/*
+ * It's up to the caller to decide when to retrieve and stash data. There is
+ * differentiation on recovery mode CONFIG_HAS_RECOVERY_MRC_CACHE, but that's
+ * only for locating where to retrieve and save the data. If a platform doesn't
+ * want to update the data then it shouldn't stash the data for saving.
+ * Similarly, if the platform doesn't need the data for booting because of a
+ * policy don't request the data.
+ */
+
+/* Get and stash data for saving provided the type passed in. The functions
+ * return < 0 on error, 0 on success. */
+int mrc_cache_get_current(int type, uint32_t version,
+				struct region_device *rdev);
+int mrc_cache_stash_data(int type, uint32_t version, const void *data,
+			size_t size);
+
+#endif /* _COMMON_MRC_CACHE_H_ */