Add TPM version checking

firmware/lib/include/rollback_index.h

 /* Copyright (c) 2010 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.
  *
  * Functions for querying, manipulating and locking rollback indices
  * stored in the TPM NVRAM.
  */
 
 #ifndef VBOOT_REFERENCE_ROLLBACK_INDEX_H_
 #define VBOOT_REFERENCE_ROLLBACK_INDEX_H_
@@ skipping 76 matching lines @@
  * global variables. */
 uint32_t RollbackS3Resume(void);
 
 /* These functions are callable from LoadFirmware().  They cannot use
  * global variables. */
 
 /* Setup must be called.  Pass developer_mode=nonzero if in developer
  * mode. */
 uint32_t RollbackFirmwareSetup(int developer_mode, uint32_t* version);
 
+/* Read may be called to get the version.  This is not necessary in
+ * the normal boot path, because RollbackFirmwareSetup() provides the
+ * same information.  It may be used in the recovery path. */
+uint32_t RollbackFirmwareRead(uint32_t* version);
+
 /* Write may be called if the versions change */
 uint32_t RollbackFirmwareWrite(uint32_t version);
 
 /* Lock must be called */
 uint32_t RollbackFirmwareLock(void);
 
 /* These functions are callable from LoadKernel().  They may use global
  * variables. */
 
 /* Recovery may be called.  If it is, this is the first time a
  * rollback function has been called this boot, so it needs to know if
  * we're in developer mode.  Pass developer_mode=nonzero if in developer
  * mode. */
 uint32_t RollbackKernelRecovery(int developer_mode);
 
-/* Read and write may be called if not in developer mode.  If called in
- * recovery mode, the effect is undefined. */
+/* Read and write may be called to read and write the kernel version. */
 uint32_t RollbackKernelRead(uint32_t* version);
 uint32_t RollbackKernelWrite(uint32_t version);
 
 /* Lock must be called.  Internally, it's ignored in recovery mode. */
 uint32_t RollbackKernelLock(void);
 
 /* The following functions are here for testing only. */
 
 /* Issue a TPM_Clear and reenable/reactivate the TPM. */
 uint32_t TPMClearAndReenable(void);
 
 #endif  /* VBOOT_REFERENCE_ROLLBACK_INDEX_H_ */