// Copyright 2021 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
library fuchsia.hardware.tpmimpl;

using zx;

/// TPM supports up to 255 localities.
alias Locality = uint8;

/// TPM registers. See "TCG PC Client Platform TPM Profile (PTP) Specification",
/// section 7.3.5 (I2C-TPM Registers) and 5.5.2.1 (FIFO Register Space
/// Addresses).
type RegisterAddress = flexible enum : uint16 {
    TPM_ACCESS = 0x4;
    TPM_INT_ENABLE = 0x8;
    TPM_INT_STATUS = 0x10;
    TPM_INT_CAPABILITY = 0x14;
    TPM_STS = 0x18;
    TPM_HASH_END = 0x20;
    TPM_DATA_FIFO = 0x24;
    TPM_HASH_START = 0x28;
    TPM_INTERFACE_ID = 0x30;
    TPM_DID_VID = 0xf00;
    TPM_RID = 0xf04;
};

/// Maximum possible amount of data that could be transferred in a single
/// transaction. Note that not all TPMs will support this amount, and the
/// TPM_INT_CAPABILITY and TPM_STS registers should be queried to get the actual
/// maximum.
const TPM_MAX_DATA_TRANSFER uint32 = 64;

/// Provides access to a TPM device.
protocol TpmImpl {
    /// Read |count| bytes from |address| in locality |locality|.
    Read(struct {
        locality Locality;
        address RegisterAddress;
        count uint32;
    }) -> (struct {
        data vector<uint8>:TPM_MAX_DATA_TRANSFER;
    }) error zx.status;

    /// Write |data| to |address| in |locality|.
    Write(struct {
        locality Locality;
        address RegisterAddress;
        data vector<uint8>:TPM_MAX_DATA_TRANSFER;
    }) -> (struct {}) error zx.status;
};