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wolfTPM/hal/tpm_io_uboot.c

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/* tpm_io_uboot.c
*
* Copyright (C) 2006-2026 wolfSSL Inc.
*
* This file is part of wolfTPM.
*
* wolfTPM 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 3 of the License, or
* (at your option) any later version.
*
* wolfTPM 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
*/
/* This example shows IO interfaces for U-boot using raw SPI
* For Raspberry Pi 4 with Infineon SLB9672 TPM HAT
* Reference: https://github.com/wolfSSL/wolfTPM/pull/451
*/
#include <wolftpm/tpm2.h>
#include <wolftpm/tpm2_tis.h>
#include "tpm_io.h"
/******************************************************************************/
/* --- BEGIN IO Callback Logic -- */
/******************************************************************************/
/* Included via tpm_io.c if WOLFTPM_INCLUDE_IO_FILE is defined */
#ifdef WOLFTPM_INCLUDE_IO_FILE
#if ! (defined(WOLFTPM_LINUX_DEV) || \
defined(WOLFTPM_SWTPM) || \
defined(WOLFTPM_WINAPI) )
/* Use the max speed by default - see tpm2_types.h for chip specific max values */
#ifndef TPM2_SPI_HZ
#define TPM2_SPI_HZ TPM2_SPI_MAX_HZ
#endif
#if defined(__UBOOT__)
#include <config.h>
#include <spi.h>
#include <asm/io.h>
#include <dm/device.h>
#include <dm/device-internal.h>
#include <dm/uclass.h>
/* SPI bus and chip select configuration for TPM
* These can be overridden in user_settings.h or board config
* Official Raspberry Pi tpm-slb9670 overlay uses CE1 (GPIO7) */
#ifndef TPM_SPI_BUS
#define TPM_SPI_BUS 0
#endif
#ifndef TPM_SPI_CS
#define TPM_SPI_CS 1 /* CE1 (GPIO7) - matches Linux tpm-slb9670 overlay */
#endif
#ifndef TPM_SPI_MAX_HZ
#define TPM_SPI_MAX_HZ 1000000 /* 1 MHz - safe default */
#endif
#define TPM_SPI_MODE SPI_MODE_0 /* Mode 0 (CPOL=0, CPHA=0) */
/* Maximum SPI frame size */
#define MAX_SPI_FRAMESIZE 64
/* Static SPI device handles */
static struct udevice *g_spi_bus = NULL;
static struct spi_slave *g_spi_slave = NULL;
static int g_spi_initialized = 0;
/* Initialize SPI for TPM communication */
static int uboot_spi_init(void)
{
int ret;
if (g_spi_initialized) {
return 0;
}
#ifdef DEBUG_WOLFTPM
printf("wolfTPM: Initializing SPI bus=%d, cs=%d, hz=%d\n",
TPM_SPI_BUS, TPM_SPI_CS, TPM_SPI_MAX_HZ);
#endif
/* Get or create SPI bus and slave device */
ret = _spi_get_bus_and_cs(TPM_SPI_BUS, TPM_SPI_CS,
TPM_SPI_MAX_HZ, TPM_SPI_MODE,
"spi_generic_drv", "wolftpm_spi",
&g_spi_bus, &g_spi_slave);
if (ret != 0) {
#ifdef DEBUG_WOLFTPM
printf("wolfTPM: SPI init failed: %d\n", ret);
#endif
return ret;
}
g_spi_initialized = 1;
#ifdef DEBUG_WOLFTPM
printf("wolfTPM: SPI initialized successfully\n");
#endif
return 0;
}
/* Raw SPI transfer for wolfTPM TIS layer
* This is called by wolfTPM's TIS implementation for register read/write.
* The txBuf/rxBuf contain TIS-formatted SPI data including the 4-byte header.
*/
int TPM2_IoCb_Uboot_SPI(TPM2_CTX* ctx, const byte* txBuf,
byte* rxBuf, word16 xferSz, void* userCtx)
{
int ret;
#ifdef WOLFTPM_CHECK_WAIT_STATE
int timeout = TPM_SPI_WAIT_RETRY;
byte tmp_rx;
#endif
(void)ctx;
(void)userCtx;
/* Initialize SPI if needed */
ret = uboot_spi_init();
if (ret != 0) {
return TPM_RC_FAILURE;
}
/* Claim the SPI bus */
ret = spi_claim_bus(g_spi_slave);
if (ret != 0) {
#ifdef DEBUG_WOLFTPM
printf("wolfTPM: Failed to claim SPI bus: %d\n", ret);
#endif
return TPM_RC_FAILURE;
}
#ifdef WOLFTPM_CHECK_WAIT_STATE
/* Send TIS header first (4 bytes) with CS held */
ret = spi_xfer(g_spi_slave, TPM_TIS_HEADER_SZ * 8,
txBuf, rxBuf, SPI_XFER_BEGIN);
if (ret != 0) {
#ifdef DEBUG_WOLFTPM
printf("wolfTPM: SPI header xfer failed: %d\n", ret);
#endif
/* End the transaction so a driver that holds CS does not leave
* it active for the next request */
spi_xfer(g_spi_slave, 0, NULL, NULL, SPI_XFER_END);
ret = TPM_RC_FAILURE;
goto cleanup;
}
/* Check for wait state - TPM holds ready bit low if busy */
if ((rxBuf[TPM_TIS_HEADER_SZ - 1] & TPM_TIS_READY_MASK) == 0) {
/* Poll for ready */
do {
ret = spi_xfer(g_spi_slave, 8, NULL, &tmp_rx, 0);
if (ret != 0) {
break;
}
if (tmp_rx & TPM_TIS_READY_MASK) {
break;
}
} while (--timeout > 0);
if (timeout <= 0 || ret != 0) {
#ifdef DEBUG_WOLFTPM
printf("wolfTPM: SPI wait state timeout\n");
#endif
/* Deassert CS */
spi_xfer(g_spi_slave, 0, NULL, NULL, SPI_XFER_END);
ret = TPM_RC_FAILURE;
goto cleanup;
}
}
/* Transfer remainder of data with CS deasserted at end */
if (xferSz > TPM_TIS_HEADER_SZ) {
ret = spi_xfer(g_spi_slave, (xferSz - TPM_TIS_HEADER_SZ) * 8,
&txBuf[TPM_TIS_HEADER_SZ],
&rxBuf[TPM_TIS_HEADER_SZ],
SPI_XFER_END);
} else {
/* Just deassert CS if no more data */
ret = spi_xfer(g_spi_slave, 0, NULL, NULL, SPI_XFER_END);
}
#else
/* No wait state handling - send entire message at once */
ret = spi_xfer(g_spi_slave, xferSz * 8, txBuf, rxBuf,
SPI_XFER_BEGIN | SPI_XFER_END);
#endif /* WOLFTPM_CHECK_WAIT_STATE */
if (ret != 0) {
ret = TPM_RC_FAILURE;
} else {
ret = TPM_RC_SUCCESS;
}
#ifdef WOLFTPM_CHECK_WAIT_STATE
cleanup:
#endif
spi_release_bus(g_spi_slave);
return ret;
}
#endif /* __UBOOT__ */
#endif /* WOLFTPM_LINUX_DEV || WOLFTPM_SWTPM || WOLFTPM_WINAPI */
#endif /* WOLFTPM_INCLUDE_IO_FILE */
/******************************************************************************/
/* --- END IO Callback Logic -- */
/******************************************************************************/
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