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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) Microsoft Corporation
*
* Authors:
* Thirupathaiah Annapureddy <thiruan@microsoft.com>
*
* Description:
* Device Driver for a firmware TPM as described here:
* https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/
*
* A reference implementation is available here:
* https://github.com/microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM
*/
#include <common.h>
#include <dm.h>
#include <log.h>
#include <tpm-v2.h>
#include <tee.h>
#include "tpm_tis.h"
#include "tpm2_ftpm_tee.h"
/**
* ftpm_tee_transceive() - send fTPM commands and retrieve fTPM response.
* @sendbuf - address of the data to send, byte by byte
* @send_size - length of the data to send
* @recvbuf - address where to read the response, byte by byte.
* @recv_len - pointer to the size of buffer
*
* Return:
* In case of success, returns 0.
* On failure, -errno
*/
static int ftpm_tee_transceive(struct udevice *dev, const u8 *sendbuf,
size_t send_size, u8 *recvbuf,
size_t *recv_len)
{
struct ftpm_tee_private *context = dev_get_priv(dev);
int rc = 0;
size_t resp_len;
u8 *resp_buf;
struct tpm_output_header *resp_header;
struct tee_invoke_arg transceive_args;
struct tee_param command_params[4];
struct tee_shm *shm;
if (send_size > MAX_COMMAND_SIZE) {
debug("%s:send_size=%zd exceeds MAX_COMMAND_SIZE\n",
__func__, send_size);
return -EIO;
}
shm = context->shm;
memset(&transceive_args, 0, sizeof(transceive_args));
memset(command_params, 0, sizeof(command_params));
/* Invoke FTPM_OPTEE_TA_SUBMIT_COMMAND function of fTPM TA */
transceive_args = (struct tee_invoke_arg) {
.func = FTPM_OPTEE_TA_SUBMIT_COMMAND,
.session = context->session,
};
/* Fill FTPM_OPTEE_TA_SUBMIT_COMMAND parameters */
/* request */
command_params[0] = (struct tee_param) {
.attr = TEE_PARAM_ATTR_TYPE_MEMREF_INPUT,
.u.memref = {
.shm = shm,
.size = send_size,
.shm_offs = 0,
},
};
memset(command_params[0].u.memref.shm->addr, 0,
(MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE));
memcpy(command_params[0].u.memref.shm->addr, sendbuf, send_size);
/* response */
command_params[1] = (struct tee_param) {
.attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT,
.u.memref = {
.shm = shm,
.size = MAX_RESPONSE_SIZE,
.shm_offs = MAX_COMMAND_SIZE,
},
};
rc = tee_invoke_func(context->tee_dev, &transceive_args, 4,
command_params);
if ((rc < 0) || (transceive_args.ret != 0)) {
debug("%s:SUBMIT_COMMAND invoke error: 0x%x\n",
__func__, transceive_args.ret);
return (rc < 0) ? rc : transceive_args.ret;
}
resp_buf = command_params[1].u.memref.shm->addr +
command_params[1].u.memref.shm_offs;
resp_header = (struct tpm_output_header *)resp_buf;
resp_len = be32_to_cpu(resp_header->length);
/* sanity check resp_len*/
if (resp_len < TPM_HEADER_SIZE) {
debug("%s:tpm response header too small\n", __func__);
return -EIO;
}
if (resp_len > MAX_RESPONSE_SIZE) {
debug("%s:resp_len=%zd exceeds MAX_RESPONSE_SIZE\n",
__func__, resp_len);
return -EIO;
}
if (resp_len > *recv_len) {
debug("%s:response length is bigger than receive buffer\n",
__func__);
return -EIO;
}
/* sanity checks look good, copy the response */
memcpy(recvbuf, resp_buf, resp_len);
*recv_len = resp_len;
return 0;
}
static int ftpm_tee_open(struct udevice *dev)
{
struct ftpm_tee_private *context = dev_get_priv(dev);
if (context->is_open)
return -EBUSY;
context->is_open = 1;
return 0;
}
static int ftpm_tee_close(struct udevice *dev)
{
struct ftpm_tee_private *context = dev_get_priv(dev);
if (context->is_open)
context->is_open = 0;
return 0;
}
static int ftpm_tee_desc(struct udevice *dev, char *buf, int size)
{
if (size < 32)
return -ENOSPC;
return snprintf(buf, size, "Microsoft OP-TEE fTPM");
}
static int ftpm_tee_match(struct tee_version_data *vers, const void *data)
{
debug("%s:vers->gen_caps =0x%x\n", __func__, vers->gen_caps);
/*
* Currently this driver only support GP Complaint OPTEE based fTPM TA
*/
return vers->gen_caps & TEE_GEN_CAP_GP;
}
static int ftpm_tee_probe(struct udevice *dev)
{
int rc;
struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
struct ftpm_tee_private *context = dev_get_priv(dev);
struct tee_open_session_arg sess_arg;
const struct tee_optee_ta_uuid uuid = TA_FTPM_UUID;
memset(context, 0, sizeof(*context));
/* Use the TPM v2 stack */
priv->version = TPM_V2;
priv->pcr_count = 24;
priv->pcr_select_min = 3;
/* Find TEE device */
context->tee_dev = tee_find_device(NULL, ftpm_tee_match, NULL, NULL);
if (!context->tee_dev) {
debug("%s:tee_find_device failed\n", __func__);
return -ENODEV;
}
/* Open a session with the fTPM TA */
memset(&sess_arg, 0, sizeof(sess_arg));
tee_optee_ta_uuid_to_octets(sess_arg.uuid, &uuid);
rc = tee_open_session(context->tee_dev, &sess_arg, 0, NULL);
if ((rc < 0) || (sess_arg.ret != 0)) {
debug("%s:tee_open_session failed, err=%x\n",
__func__, sess_arg.ret);
return -EIO;
}
context->session = sess_arg.session;
/* Allocate dynamic shared memory with fTPM TA */
rc = tee_shm_alloc(context->tee_dev,
MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE,
0, &context->shm);
if (rc) {
debug("%s:tee_shm_alloc failed with rc = %d\n", __func__, rc);
goto out_shm_alloc;
}
return 0;
out_shm_alloc:
tee_close_session(context->tee_dev, context->session);
return rc;
}
static int ftpm_tee_remove(struct udevice *dev)
{
struct ftpm_tee_private *context = dev_get_priv(dev);
int rc;
/* tee_pre_remove frees any leftover TEE shared memory */
/* close the existing session with fTPM TA*/
rc = tee_close_session(context->tee_dev, context->session);
debug("%s: tee_close_session - rc =%d\n", __func__, rc);
return 0;
}
static const struct tpm_ops ftpm_tee_ops = {
.open = ftpm_tee_open,
.close = ftpm_tee_close,
.get_desc = ftpm_tee_desc,
.xfer = ftpm_tee_transceive,
};
static const struct udevice_id ftpm_tee_ids[] = {
{ .compatible = "microsoft,ftpm" },
{ }
};
U_BOOT_DRIVER(ftpm_tee) = {
.name = "ftpm_tee",
.id = UCLASS_TPM,
.of_match = ftpm_tee_ids,
.ops = &ftpm_tee_ops,
.probe = ftpm_tee_probe,
.remove = ftpm_tee_remove,
.flags = DM_FLAG_OS_PREPARE,
.priv_auto_alloc_size = sizeof(struct ftpm_tee_private),
};
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