linux_uart.hpp

#pragma once
 
#define termios asmtermios
#include <asm/termbits.h>
#undef termios
#include <fcntl.h>
#include <libudev.h>
#include <linux/serial.h>
#include <sys/ioctl.h>
#include <sys/select.h>
#include <termios.h>
#include <unistd.h>
 
#include <cstddef>
#include <cstdint>
#include <algorithm>
#include <filesystem>
#include <system_error>
#include <vector>
 
#include "libxr_def.hpp"
#include "libxr_rw.hpp"
#include "semaphore.hpp"
#include "uart.hpp"
 
namespace LibXR
{
class LinuxUART : public UART
{
 public:
  LinuxUART(const char* dev_path, unsigned int baudrate = 115200,
            Parity parity = Parity::NO_PARITY, uint8_t data_bits = 8,
            uint8_t stop_bits = 1, uint32_t tx_queue_size = 5, size_t buffer_size = 512,
            size_t thread_stack_size = 65536)
      : UART(&_read_port, &_write_port),
        rx_buff_(new uint8_t[buffer_size]),
        tx_buff_(new uint8_t[buffer_size]),
        buff_size_(buffer_size),
        _read_port(buffer_size),
        _write_port(tx_queue_size, buffer_size)
  {
    ASSERT(buff_size_ > 0);
 
    while (!std::filesystem::exists(dev_path))
    {
      XR_LOG_WARN("Cannot find UART device: %s, retrying...", dev_path);
      Thread::Sleep(100);
    }
 
    device_path_ = GetByPathForTTY(dev_path);
 
    fd_ = open(device_path_.c_str(), O_RDWR | O_NOCTTY);
    if (fd_ < 0)
    {
      XR_LOG_ERROR("Cannot open UART device: %s", device_path_.c_str());
      ASSERT(false);
    }
    else
    {
      XR_LOG_PASS("Open UART device: %s", device_path_.c_str());
    }
 
    config_ = {};
    config_.baudrate = baudrate;
    config_.parity = parity;
    config_.data_bits = data_bits;
    config_.stop_bits = stop_bits;
 
    SetConfig(config_);
 
    _read_port = ReadFun;
    _write_port = WriteFun;
 
    rx_thread_.Create<LinuxUART*>(
        this, [](LinuxUART* self) { self->RxLoop(); }, "rx_uart", thread_stack_size,
        Thread::Priority::REALTIME);
 
    tx_thread_.Create<LinuxUART*>(
        this, [](LinuxUART* self) { self->TxLoop(); }, "tx_uart", thread_stack_size,
        Thread::Priority::REALTIME);
  }
 
  LinuxUART(const std::string& vid, const std::string& pid,
            unsigned int baudrate = 115200, Parity parity = Parity::NO_PARITY,
            uint8_t data_bits = 8, uint8_t stop_bits = 1, uint32_t tx_queue_size = 5,
            size_t buffer_size = 512, size_t thread_stack_size = 65536)
      : LinuxUART(vid, pid, "", baudrate, parity, data_bits, stop_bits, tx_queue_size,
                  buffer_size, thread_stack_size)
  {
  }
 
  LinuxUART(const std::string& vid, const std::string& pid, const std::string& serial,
            unsigned int baudrate = 115200, Parity parity = Parity::NO_PARITY,
            uint8_t data_bits = 8, uint8_t stop_bits = 1, uint32_t tx_queue_size = 5,
            size_t buffer_size = 512, size_t thread_stack_size = 65536)
      : UART(&_read_port, &_write_port),
        rx_buff_(new uint8_t[buffer_size]),
        tx_buff_(new uint8_t[buffer_size]),
        buff_size_(buffer_size),
        _read_port(buffer_size),
        _write_port(tx_queue_size, buffer_size)
  {
    while (!FindUSBTTYByVidPid(vid, pid, serial, device_path_))
    {
      if (serial.empty())
      {
        XR_LOG_WARN("Cannot find USB TTY device with VID=%s PID=%s, retrying...",
                    vid.c_str(), pid.c_str());
      }
      else
      {
        XR_LOG_WARN("Cannot find USB TTY device with VID=%s PID=%s SERIAL=%s, retrying...",
                    vid.c_str(), pid.c_str(), serial.c_str());
      }
      Thread::Sleep(100);
    }
 
    XR_LOG_PASS("Found USB TTY: %s", device_path_.c_str());
 
    if (std::filesystem::exists(device_path_) == false)
    {
      XR_LOG_ERROR("Cannot find UART device: %s", device_path_.c_str());
      ASSERT(false);
      return;
    }
 
    device_path_ = GetByPathForTTY(device_path_);
 
    fd_ = open(device_path_.c_str(), O_RDWR | O_NOCTTY);
    if (fd_ < 0)
    {
      XR_LOG_ERROR("Cannot open UART device: %s", device_path_.c_str());
      ASSERT(false);
    }
    else
    {
      XR_LOG_PASS("Open UART device: %s", device_path_.c_str());
    }
 
    config_ = {};
    config_.baudrate = baudrate;
    config_.parity = parity;
    config_.data_bits = data_bits;
    config_.stop_bits = stop_bits;
 
    SetConfig(config_);
 
    _read_port = ReadFun;
    _write_port = WriteFun;
 
    rx_thread_.Create<LinuxUART*>(
        this, [](LinuxUART* self) { self->RxLoop(); }, "rx_uart", thread_stack_size,
        Thread::Priority::REALTIME);
 
    tx_thread_.Create<LinuxUART*>(
        this, [](LinuxUART* self) { self->TxLoop(); }, "tx_uart", thread_stack_size,
        Thread::Priority::REALTIME);
  }
 
  std::string GetByPathForTTY(const std::string& tty_name)
  {
    const std::string BASE = "/dev/serial/by-path";
    if (strncmp(tty_name.c_str(), BASE.c_str(), BASE.length()) == 0 ||
        !std::filesystem::exists(BASE))
    {
      return tty_name;
    }
    for (const auto& entry : std::filesystem::directory_iterator(BASE))
    {
      std::error_code ec;
      const auto full = std::filesystem::canonical(entry.path(), ec);
      if (ec)
      {
        continue;
      }
      if (full == tty_name)
      {
        return entry.path().string();  // 返回符号链接路径
      }
    }
    return tty_name;  // 未命中 by-path 时保留原始 tty 路径
  }
 
  static bool FindUSBTTYByVidPid(const std::string& target_vid,
                                 const std::string& target_pid,
                                 const std::string& target_serial, std::string& tty_path)
  {
    struct udev* udev = udev_new();
    if (!udev)
    {
      XR_LOG_ERROR("Cannot create udev context");
      return false;
    }
 
    struct udev_enumerate* enumerate = udev_enumerate_new(udev);
    udev_enumerate_add_match_subsystem(enumerate, "tty");
    udev_enumerate_scan_devices(enumerate);
 
    struct udev_list_entry* devices = udev_enumerate_get_list_entry(enumerate);
    struct udev_list_entry* entry = nullptr;
    std::vector<std::string> matches;
 
    udev_list_entry_foreach(entry, devices)
    {
      const char* path = udev_list_entry_get_name(entry);
      struct udev_device* tty_dev = udev_device_new_from_syspath(udev, path);
      if (!tty_dev)
      {
        continue;
      }
 
      struct udev_device* usb_dev =
          udev_device_get_parent_with_subsystem_devtype(tty_dev, "usb", "usb_device");
 
      if (usb_dev)
      {
        const char* vid = udev_device_get_sysattr_value(usb_dev, "idVendor");
        const char* pid = udev_device_get_sysattr_value(usb_dev, "idProduct");
        const char* serial = udev_device_get_sysattr_value(usb_dev, "serial");
 
        if (vid && pid && target_vid == vid && target_pid == pid &&
            (target_serial.empty() || (serial && target_serial == serial)))
        {
          const char* devnode = udev_device_get_devnode(tty_dev);
          if (devnode)
          {
            matches.emplace_back(devnode);
          }
        }
      }
 
      udev_device_unref(tty_dev);
    }
 
    udev_enumerate_unref(enumerate);
    udev_unref(udev);
    if (matches.empty())
    {
      return false;
    }
 
    std::sort(matches.begin(), matches.end());
    tty_path = matches.front();
 
    if (matches.size() > 1 && target_serial.empty())
    {
      XR_LOG_WARN(
          "Multiple USB TTY devices found with VID=%s PID=%s, using %s. Specify serial to disambiguate.",
          target_vid.c_str(), target_pid.c_str(), tty_path.c_str());
    }
 
    return true;
  }
 
  void SetLowLatency(int fd)
  {
    struct serial_struct serinfo;
    ioctl(fd, TIOCGSERIAL, &serinfo);
    serinfo.flags |= ASYNC_LOW_LATENCY;
    ioctl(fd, TIOCSSERIAL, &serinfo);
  }
 
  ErrorCode SetConfig(UART::Configuration config) override
  {
    if (&config != &config_)
    {
      config_ = config;
    }
 
    struct termios2 tio{};
    if (ioctl(fd_, TCGETS2, &tio) != 0)
    {
      return ErrorCode::INIT_ERR;
    }
 
    // 设置自定义波特率
    tio.c_cflag &= ~CBAUD;
    tio.c_cflag |= BOTHER;
    tio.c_ispeed = config.baudrate;
    tio.c_ospeed = config.baudrate;
 
    // 输入模式：关闭软件流控、特殊字符处理
    tio.c_iflag &= ~(IXON | IXOFF | IXANY | ISTRIP | IGNCR | INLCR | ICRNL
#ifdef IUCLC
                     | IUCLC
#endif
    );
 
    // 输出模式：关闭所有加工
    tio.c_oflag &= ~(OPOST
#ifdef ONLCR
                     | ONLCR
#endif
#ifdef OCRNL
                     | OCRNL
#endif
#ifdef ONOCR
                     | ONOCR
#endif
#ifdef ONLRET
                     | ONLRET
#endif
    );
 
    // 本地模式：禁用行缓冲、回显、信号中断
    tio.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
 
    // 控制模式：设置数据位、校验、停止位、流控
    tio.c_cflag &= ~CSIZE;
    switch (config.data_bits)
    {
      case 5:
        tio.c_cflag |= CS5;
        break;
      case 6:
        tio.c_cflag |= CS6;
        break;
      case 7:
        tio.c_cflag |= CS7;
        break;
      case 8:
        tio.c_cflag |= CS8;
        break;
      default:
        return ErrorCode::ARG_ERR;
    }
 
    // 停止位
    tio.c_cflag &= ~CSTOPB;
    if (config.stop_bits == 2)
    {
      tio.c_cflag |= CSTOPB;
    }
 
    // 奇偶校验
    switch (config.parity)
    {
      case UART::Parity::NO_PARITY:
        tio.c_cflag &= ~PARENB;
        break;
      case UART::Parity::EVEN:
        tio.c_cflag |= PARENB;
        tio.c_cflag &= ~PARODD;
        break;
      case UART::Parity::ODD:
        tio.c_cflag |= PARENB;
        tio.c_cflag |= PARODD;
        break;
    }
 
    // 禁用硬件流控
    tio.c_cflag &= ~CRTSCTS;
 
    // 启用本地模式、读功能
    tio.c_cflag |= (CLOCAL | CREAD);
 
    // 控制字符配置：阻塞直到读到 1 字节
    // for (int i = 0; i < NCCS; ++i) tio.c_cc[i] = 0;
    tio.c_cc[VTIME] = 0;
    tio.c_cc[VMIN] = 1;
 
    if (ioctl(fd_, TCSETS2, &tio) != 0)
    {
      return ErrorCode::INIT_ERR;
    }
 
    SetLowLatency(fd_);
 
    tcflush(fd_, TCIOFLUSH);
 
    return ErrorCode::OK;
  }
 
  static ErrorCode ReadFun(ReadPort&, bool) { return ErrorCode::EMPTY; }
 
  static ErrorCode WriteFun(WritePort& port, bool)
  {
    auto* uart = LibXR::ContainerOf(&port, &LinuxUART::_write_port);
    uart->write_sem_.Post();
    return ErrorCode::OK;
  }
 
 private:
  void RxLoop()
  {
    while (true)
    {
      if (!connected_)
      {
        close(fd_);
        fd_ = open(device_path_.c_str(), O_RDWR | O_NOCTTY);
 
        if (fd_ < 0)
        {
          XR_LOG_WARN("Cannot open UART device: %s", device_path_.c_str());
          Thread::Sleep(1000);
        }
        else
        {
          SetConfig(config_);
          XR_LOG_PASS("Reopen UART device: %s", device_path_.c_str());
          connected_ = true;
        }
      }
      auto n = read(fd_, rx_buff_, buff_size_);
      if (n > 0)
      {
        read_port_->queue_data_->PushBatch(rx_buff_, n);
        read_port_->ProcessPendingReads(false);
      }
      else
      {
        XR_LOG_WARN("Cannot read UART device: %s", device_path_.c_str());
        connected_ = false;
      }
    }
  }
 
  void TxLoop()
  {
    WriteInfoBlock info;
    while (true)
    {
      if (!connected_)
      {
        Thread::Sleep(1);
        continue;
      }
 
      if (write_sem_.Wait() != ErrorCode::OK)
      {
        continue;
      }
 
      if (write_port_->queue_info_->Pop(info) == ErrorCode::OK)
      {
        if (write_port_->queue_data_->PopBatch(tx_buff_, info.data.size_) ==
            ErrorCode::OK)
        {
          auto written = write(fd_, tx_buff_, info.data.size_);
          if (written < 0)
          {
            XR_LOG_WARN("Cannot write UART device: %s", device_path_.c_str());
            connected_ = false;
          }
          write_port_->Finish(false,
                              (written == static_cast<int>(info.data.size_))
                                  ? ErrorCode::OK
                                  : ErrorCode::FAILED,
                              info);
        }
        else
        {
          info.op.UpdateStatus(false, ErrorCode::FAILED);
        }
      }
    }
  }
 
  int fd_ = -1;
  bool connected_ = true;
  Configuration config_;
  std::string device_path_;
  Thread rx_thread_;
  Thread tx_thread_;
  uint8_t* rx_buff_ = nullptr;
  uint8_t* tx_buff_ = nullptr;
  size_t buff_size_ = 0;
  Semaphore write_sem_;
  Mutex read_mutex_;
 
  ReadPort _read_port;    // NOLINT
  WritePort _write_port;  // NOLINT
};
 
}  // namespace LibXR