typecd/port.cc

// Copyright 2020 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "typecd/port.h"

#include <base/files/file_util.h>
#include <base/logging.h>
#include <base/strings/string_util.h>
#include <re2/re2.h>

namespace {

constexpr char kDataRoleDRPRegex[] = R"(.*\[(\w+)\].*)";
constexpr uint16_t kDPAltModeSID = 0xff01;
constexpr uint16_t kTBTAltModeVID = 0x8087;

constexpr uint32_t kIDHeaderVDOModalOperationBitField = (1 << 26);

}  // namespace

namespace typecd {

Port::Port(const base::FilePath& syspath, int port_num)
    : syspath_(syspath), port_num_(port_num) {
  LOG(INFO) << "Port " << port_num_ << " enumerated.";
}

void Port::AddCable(const base::FilePath& path) {
  if (cable_) {
    LOG(WARNING) << "Cable already exists for port " << port_num_;
    return;
  }
  cable_ = std::make_unique<Cable>(path);

  LOG(INFO) << "Cable enumerated for port " << port_num_;
}

void Port::RemoveCable() {
  if (!cable_) {
    LOG(WARNING) << "No partner present for port " << port_num_;
    return;
  }
  cable_.reset();

  LOG(INFO) << "Cable removed for port " << port_num_;
}

void Port::AddPartner(const base::FilePath& path) {
  if (partner_) {
    LOG(WARNING) << "Partner already exists for port " << port_num_;
    return;
  }
  partner_ = std::make_unique<Partner>(path);

  LOG(INFO) << "Partner enumerated for port " << port_num_;
}

void Port::RemovePartner() {
  if (!partner_) {
    LOG(WARNING) << "No partner present for port " << port_num_;
    return;
  }
  partner_.reset();

  LOG(INFO) << "Partner removed for port " << port_num_;
}

void Port::AddRemovePartnerAltMode(const base::FilePath& path, bool added) {
  if (!partner_) {
    LOG(WARNING) << "Trying to add alt mode for non-existent partner on port "
                 << port_num_;
    return;
  }

  if (added) {
    if (!partner_->AddAltMode(path))
      LOG(ERROR) << "Failed to add alt mode for port " << port_num_
                 << " at path " << path;
  } else {
    partner_->RemoveAltMode(path);
  }
}

std::string Port::GetDataRole() {
  std::string data_role;
  std::string sysfs_str;
  auto path = syspath_.Append("data_role");

  if (!base::ReadFileToString(path, &sysfs_str)) {
    LOG(ERROR) << "Couldn't read sysfs path " << path;
    goto end;
  }

  // First check for a dual role port, in which case the current role is in
  // box-brackets. For example: [host] device
  if (!RE2::FullMatch(sysfs_str, kDataRoleDRPRegex, &data_role)) {
    LOG(INFO)
        << "Couldn't determine role, assuming DRP(Dual Role Port) for port "
        << port_num_;
  }

  if (data_role == "")
    data_role = sysfs_str;

  base::TrimWhitespaceASCII(data_role, base::TRIM_ALL, &data_role);

  if (data_role != "host" && data_role != "device")
    data_role = "";

end:
  return data_role;
}

bool Port::CanEnterDPAltMode() {
  if (!IsPartnerAltModePresent(kDPAltModeSID)) {
    LOG(INFO) << "DP alt mode not supported by partner.";
    return false;
  }

  return true;
}

// Mode entry check for TBT compatibility mode.
// Ref:
//   USB Type-C Connector Spec, release 2.0
//   Figure F-1.
bool Port::CanEnterTBTCompatibilityMode() {
  if (!cable_) {
    LOG(ERROR) << "No cable object registered, can't enter TBT Compat mode.";
    return false;
  }

  // Check if the Cable meets TBT3 speed requirements.
  if (!cable_->TBT3PDIdentityCheck())
    return false;

  // Check if the partner supports Modal Operation
  // Ref:
  //   USB PD spec, rev 3.0, v2.0.
  //   Table 6-29
  auto partner_idh = partner_->GetIdHeaderVDO();
  if (!(partner_idh & kIDHeaderVDOModalOperationBitField)) {
    return false;
  }

  // Check if the partner supports TBT compatibility mode.
  if (!IsPartnerAltModePresent(kTBTAltModeVID)) {
    LOG(INFO) << "TBT Compat mode not supported by partner.";
    return false;
  }

  return true;
}

bool Port::IsPartnerAltModePresent(uint16_t altmode_sid) {
  auto num_alt_modes = partner_->GetNumAltModes();
  for (int i = 0; i < num_alt_modes; i++) {
    auto alt_mode = partner_->GetAltMode(i);
    if (!alt_mode)
      continue;
    if (alt_mode->GetSVID() == altmode_sid)
      return true;
  }

  return false;
}

}  // namespace typecd