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 <filesystem>
 
#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)
      : UART(&_read_port, &_write_port),
        write_sem_(0),
        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);
 
    if (std::filesystem::exists(dev_path) == false)
    {
      XR_LOG_ERROR("Cannot find UART device: %s", dev_path);
      ASSERT(false);
    }
 
    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_ = {.baudrate = baudrate,
               .parity = parity,
               .data_bits = data_bits,
               .stop_bits = stop_bits};
 
    SetConfig(config_);
 
    _read_port = ReadFun;
    _write_port = WriteFun;
 
    rx_thread_.Create<LinuxUART *>(
        this, [](LinuxUART *self) { self->RxLoop(); }, "rx_uart", 8192,
        Thread::Priority::REALTIME);
 
    tx_thread_.Create<LinuxUART *>(
        this, [](LinuxUART *self) { self->TxLoop(); }, "tx_uart", 8192,
        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)
      : UART(&_read_port, &_write_port),
        write_sem_(0),
        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, device_path_))
    {
      XR_LOG_WARN("Cannot find USB TTY device with VID=%s PID=%s, retrying...",
                  vid.c_str(), pid.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_);
      ASSERT(false);
    }
 
    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_ = {.baudrate = baudrate,
               .parity = parity,
               .data_bits = data_bits,
               .stop_bits = stop_bits};
 
    SetConfig(config_);
 
    _read_port = ReadFun;
    _write_port = WriteFun;
 
    rx_thread_.Create<LinuxUART *>(
        this, [](LinuxUART *self) { self->RxLoop(); }, "rx_uart", 8192,
        Thread::Priority::REALTIME);
 
    tx_thread_.Create<LinuxUART *>(
        this, [](LinuxUART *self) { self->TxLoop(); }, "tx_uart", 8192,
        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::string full = std::filesystem::canonical(entry.path());
      if (full == tty_name)
      {
        return entry.path();  // 返回符号链接路径
      }
    }
    return "";  // 没找到
  }
 
  static bool FindUSBTTYByVidPid(const std::string &target_vid,
                                 const std::string &target_pid, 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;
    bool found = false;
 
    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");
 
        if (vid && pid && target_vid == vid && target_pid == pid)
        {
          const char *devnode = udev_device_get_devnode(tty_dev);
          if (devnode)
          {
            tty_path = devnode;
            found = true;
            udev_device_unref(tty_dev);
            break;
          }
        }
      }
 
      udev_device_unref(tty_dev);
    }
 
    udev_enumerate_unref(enumerate);
    udev_unref(udev);
    return found;
  }
 
  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 &port) { return ErrorCode::EMPTY; }
 
  static ErrorCode WriteFun(WritePort &port)
  {
    auto uart = CONTAINER_OF(&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, written);
        }
        else
        {
          ASSERT(false);
          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;
  WritePort _write_port;
};
 
}  // namespace LibXR