// 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      = sizeof(struct ftpm_tee_private),
};