Add NV storage API to vboot reference

firmware/include/vboot_nvstorage.h

+/* Copyright (c) 2011 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.
+ */
+
+/* Non-volatile storage routines.
+ */
+
+#ifndef VBOOT_REFERENCE_NVSTORAGE_H_
+#define VBOOT_REFERENCE_NVSTORAGE_H_
+
+#define NV_BLOCK_SIZE 16  /* Size of NV storage block in bytes */
+
+typedef struct VbNvContext {
+  /* Raw NV data.  Caller must fill this before calling VbNvOpen(). */
+  uint8_t raw[NV_BLOCK_SIZE];
+  /* Flag indicating whether raw data has changed.  Set by VbNvClose() if
+   * the raw data has changed and needs to be stored to the underlying
+   * non-volatile data store. */
+  int raw_changed;
+
+  /* Internal data for NV storage routines.  Caller should not touch
+   * these fields. */
+  int regenerate_crc;
+
+} VbNvContext;
+
+
+/* Parameter type for VbNvGet(), VbNvSet(). */
+typedef enum VbNvParam {
+  VBNV_FIRMWARE_SETTINGS_RESET = 0,
+  VBNV_KERNEL_SETTINGS_RESET,
+  VBNV_DEBUG_RESET_MODE,
+  VBNV_TRY_B_COUNT,
+  VBNV_RECOVERY_REQUEST,
+  VBNV_LOCALIZATION_INDEX,
+  VBNV_KERNEL_FIELD,
+} VbNvParam;
+
+
+/* Initialize the NV storage library.  This must be called before any
+ * other functions in this library. Returns 0 if success, non-zero if
+ * error. */
+int VbNvOpen(VbNvContext* context);
+
+/* Clean up and flush changes back to the raw data.  This must be
+ * called after other functions in this library.  Caller must check
+ * context.raw_changed after calling tis function.  Returns 0 if
+ * success, non-zero if error. */
+int VbNvClose(VbNvContext* context);
+
+/* Read a NV storage parameter into *dest.  Returns 0 if success,
+ * non-zero if error. */
+int VbNvGet(VbNvContext* context, VbNvParam param, uint32_t* dest);
+
+/* Set a NV storage param to a new value.  Returns 0 if success,
+ * non-zero if error. */
+int VbNvSet(VbNvContext* context, VbNvParam param, uint32_t value);
+
+
+#endif  /* VBOOT_REFERENCE_NVSTORAGE_H_ */