src/drivers/tpm/tpm_utils.h

/*
 * Copyright 2017 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; either version 2 of
 * the License, or (at your option) any later version.
 *
 * 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 __DRIVERS_TPM_TPM_UTILS_H__
#define __DRIVERS_TPM_TPM_UTILS_H__

#include <libpayload.h>

/*
 * This structure describes the header used for TPM Vendor commands and their
 * responses. Command payload or response (if any) are concatenated with the
 * header. All values are transmitted in big endian format.
 */

struct tpm_vendor_header {
	uint16_t tag;		  /* TPM_ST_NO_SESSIONS */
	uint32_t size;		  /* including this header */
	uint32_t code;		  /* Command out, Response code back. */
	uint16_t subcommand_code; /* Vendor subcommand, not used on response. */
} __attribute__((packed));

/*
 * TPMv2 Spec mandates that vendor-specific command codes have bit 29 set,
 * while bits 15-0 indicate the command. All other bits should be zero. We
 * define one of those 16-bit command values for Cr50 purposes, and use the
 * subcommand_code in struct TpmCmdHeader to further distinguish the desired
 * operation.
 */
#define TPM_CC_VENDOR_BIT   0x20000000

/* Cr50 vendor-specific subcommand codes. 16 bits available. */
enum vendor_cmd_cc {
	VENDOR_CC_REPORT_TPM_STATE = 23,
	VENDOR_CC_GET_REC_BTN = 29,
};

#define TPM_ST_NO_SESSIONS 0x8001

static inline void marshal_u16(void *buf, u16 val) { be16enc(buf, val); }
static inline void marshal_u32(void *buf, u32 val) { be32enc(buf, val); }
static inline uint32_t unmarshal_u32(void *buf) { return be32dec(buf); }

#endif /* __DRIVERS_TPM_TPM_UTILS_H__*/