自己写的Linux下的串口操作

代码是纯C写的，大于115200的非标准波特率是和平台相关的，这里是基于PC104的，写读取操作时参考了AUPE，写非标准波特率时参考了stackoverflow的一个帖子，当时竟然忘了存了。。。

#ifndef USER_TYPE_H_#define USER_TYPE_H_#define SUCCESS0#define FAILURE1#define STRING(x)#xtypedef unsigned char  UCHAR;typedef unsigned short USHORT;typedef unsigned int   UINT;typedef unsigned long  ULONG;typedef unsigned int   uint24;#endif

#ifndef SERIAL_PORT_H_#define SERIAL_PORT_H_#include "user_type.h"/* * configuration of a serial port */struct Config{int  baudRate;      //baud rateint  dataBits;  //data bitschar parity;  //parityint  stopBits;  //stop bitsint  minToRead;  //minimum bytes to return when calling readint  timeoutBetweenBytes; //time out between bytes, unit in 100ms//baseAddr is used only when baudRate is supported nonstandard baud rateUSHORT baseAddr;  //serial port's hardware base address};/* * This function is used to check if the baud rate is supported.*@param baudRate: baud rate to check*@return:     1 if the baud rate is supported     0 otherwise*/int isSupportedBaudRate(int baudRate);/* * This function is used to get the type of given baudRate*@param baudRate: baud rate to check*@return:     0 if given baud is supported standard baud rate     1 if given baud is supported nonstandard baud rate    -1 if given baud is not supported */int getBaudRateType(int baudRate);/* * This function is used to check if the data bits is supported.*@param dataBits: data bits to check*@return:     1 if the dataBits is supported     0 otherwise*/int isSupportedDataBits(int dataBits);/* * This function is used to check if the parity is supported.*@param parity: parity to check*@return:     1 if the parity is supported     0 otherwise*/int isSupportedParity(char parity);/* * This function is used to check if the stop bits is supported.*@param stopBits: stop bits to check*@return:     1 if the stopBits is supported     0 otherwise*/int isSupportedDataBits(int stopBits);/* * This function is used to open a serial port.*@param dev:     serial port's system file path*@param mode:     "ReadOnly","WriteOnly","ReadWrite"*@param blocking: whether to set the read mode to be blocking or not*@return:     corresponding file handle if open the serial port successfully     a negative number otherwise*/int openSerialPort(const char* dev,const char* mode,int         blocking);/* * This function is used to set configuration for the serial port.*@param fd:            file handle of target serial port*@param baud:         38400, 19200, 9600, 4800, 2400, 1200, 300*@param dataBits:         7 or 8*@param stopBits:            1 or 2*@param parity:              'N' or 'E' or 'O' or 'S'*@param minToRead:       minimum bytes to return when calling read*@param timeoutBetweenBytes: time out between bytes, unit in 100ms*@return: 0 if done configuration successfully       negative numbers if error happens*/int configurateSerialPort(int fd,int baud,int dataBits,char parity,int stopBits,int minToRead,int timeoutBetweenBytes);/* * This function is used to open a serial port.*@param dev:   serial port's system file path*@param mode:  "ReadOnly","WriteOnly","ReadWrite"*@param blocking: whether to set the read mode to be blocking or not*@param pConfig: const pointer to a Config structure*@return:     corresponding file handle if open the serial port successfully     a negative number otherwise*/int openAndConfigurateSerialPort(const char* dev,const char* mode,int         blocking,const struct Config* pConfig);/* * This function is used to close a serial port. * @param fd: serial port handle * @return: * SUCCESS if successfully closed the port * FAILURE if fail to close */int closeSerialPort(int fd);/* * This function is send frame.*@param fd:    file descriptor of a serial port*@param frame: pointer of the frame*@param len:   bytes to send*@return: bytes successfully sent*/int send(int   fd,void* frame,int   len);/* * This function is receive within given time limit.*@param fd:     file descriptor of a serial port*@param buf:  pointer to where to hold bytes received*@param nbytes:  target bytes to receive*@param timeoutSec:  second part of timeout*@param timeoutMicrosec: microsecond part of timeout*@return: if time runs out before nbytes has been received, returns how many actually received else return nbytes*/int treadn(int fd, void *buf, int nbytes, int timeoutSec, int timeoutMicrosec);/* * This function is receive frame.*@param fd:    file descriptor of a serial port*@param frame: pointer to where to hold bytes received*@param maxlen: maximum bytes to receive*@return: bytes successfully read once*/int receive(int   fd,void* frame,int   maxLen);#endif /* SERIAL_PORT_H_ */

//local headers#include "user_type.h"#include "serial_port.h"//standard C headers#include <stdio.h>#include <string.h>#include <stdlib.h>#include <errno.h>//linux headers#include <unistd.h>#include <fcntl.h>#include <sys/ioctl.h>#include <linux/serial.h>#include <sys/io.h>#include <termios.h>#include <sys/time.h>int getBaudRateType(int baudRate){//if not in valid rangeif(baudRate <= 0 || baudRate > 1500000) return -1;//if supported standardif(baudRate == 110 ||   baudRate == 300 ||   baudRate == 600 ||   baudRate == 1200 ||   baudRate == 2400 ||   baudRate == 4800 ||   baudRate == 9600 ||   baudRate == 14400 ||   baudRate == 19200 ||   baudRate == 38400 ||   baudRate == 57600 ||   baudRate == 115200  ) return 0;//if supported nonstandardif(115200 % baudRate == 0 && 115200 / baudRate < 256) return 1;if(460800 % baudRate == 0 && 460800 / baudRate < 256) return 1;if(921600 % baudRate == 0 && 921600 / baudRate < 256) return 1;if(1500000 % baudRate == 0 && 1500000 / baudRate < 256) return 1;return -1;}int isSupportedBaudRate(int baudRate){return getBaudRateType(baudRate) >= 0;}int isSupportedDataBits(int dataBits){return dataBits >= 5 && dataBits <= 8;}int isSupportedParity(char parity){return parity == 'N' || parity == 'n' ||   parity == 'O' || parity == 'o' ||   parity == 'E' || parity == 'e' ||   parity == 'S' || parity == 's';}int isSupportedStopBits(int stopBits){return stopBits == 1 || stopBits == 2;}int closeSerialPort(int fd){if(0 == close(fd)) return SUCCESS;return FAILURE;}int openSerialPort(const char* dev, const char* mode, int blocking){int fd = -1;if(strcmp(mode, "ReadOnly") == 0)fd = open(dev, O_RDONLY | O_NOCTTY | O_NDELAY);else if(strcmp(mode, "WriteOnly") == 0)fd = open(dev, O_WRONLY | O_NOCTTY | O_NDELAY);else if(strcmp(mode, "ReadWrite") == 0)fd = open(dev, O_RDWR   | O_NOCTTY | O_NDELAY);elsefprintf(stderr, "error@openSerialPort: invalid open mode\n");if(fd > 0 && blocking){if(0 > fcntl(fd, F_SETFL, 0)) perror("fcntl F_SETFL");}return fd;}int configurateSerialPort(int fd, int baud, int dataBits, char parity, int stopBits, int minToRead, int timeoutBetweenBytes){struct termios config;//step 0: get current attribute of the serial portif(tcgetattr(fd, &config) != 0){fprintf(stderr, "error@configSerialPort: fail to tcgetattr(fd, &config)\n");return FAILURE;}//step 1: translate baud into a system parameterswitch(baud){case 115200: baud = B115200; break;case 57600:  baud = B57600;  break;case 38400:  baud = B38400;  break;case 19200:  baud = B19200;  break;case 9600:   baud = B9600;   break;case 4800:   baud = B4800;   break;case 2400:   baud = B2400;   break;case 1200:   baud = B1200;   break;case 300:    baud = B300;    break;case 110:    baud = B110;    break;default:fprintf(stderr, "error@configSerialPort: invalid baud rate\n");return FAILURE;}//step 2: set input/output baudif(cfsetispeed(&config, baud) != 0){fprintf(stderr, "error@configSerialPort: fail to cfsetispeed(&config, baud)\n");return FAILURE;}    if(cfsetospeed(&config, baud) != 0){    fprintf(stderr, "error@configSerialPort: fail to cfsetospeed(&config, baud)\n");return FAILURE;}//step 3: set stream attribute//to disable input software stream controlconfig.c_iflag &= ~(IXON | IXOFF | IXANY);config.c_iflag &= ~(INLCR | ICRNL | IGNCR);//to let every char for every charconfig.c_oflag  &= ~OPOST;config.c_oflag &= ~(ONLCR | OCRNL);//to make output no wait for a '\n'    config.c_lflag  &= ~(ICANON | ECHO | ECHOE | ISIG);//step 4: set data bitsconfig.c_cflag &= ~CSIZE;switch (dataBits){case 5: config.c_cflag |= CS5; break;    case 6: config.c_cflag |= CS6; break;        case 7: config.c_cflag |= CS7; break;        case 8: config.c_cflag |= CS8; break;        default:        fprintf(stderr, "error@configSerialPort: invalid data bits\n");        return FAILURE;    }//step 5: set parity    switch (parity){        case 'n': case 'N':            config.c_cflag &= ~PARENB;    /* Clear parity enable */            config.c_iflag &= ~INPCK;     /* Enable parity checking */            break;        case 'o': case 'O':            config.c_cflag |= (PARODD | PARENB); /* 设置为奇效验*/            config.c_iflag |= INPCK;             /* Disnable parity checking */            break;        case 'e': case 'E':            config.c_cflag |= PARENB;      /* Enable parity */            config.c_cflag &= ~PARODD;     /* 转换为偶效验*/            config.c_iflag |= INPCK;       /* Disnable parity checking */            break;        case 'S': case 's':            config.c_cflag &= ~PARENB;/*as no parity*/            config.c_cflag &= ~CSTOPB;            break;        default:        fprintf(stderr, "error@configSerialPort: invalid parity\n");            return FAILURE;    }//step 6: set stop bits    switch (stopBits){        case 1:            config.c_cflag &= ~CSTOPB; break;        case 2:            config.c_cflag |= CSTOPB;  break;        default:        fprintf(stderr, "error@configSerialPort: invalid stop bits\n");        return FAILURE;}//step 7: set read attributeconfig.c_cc[VMIN] = minToRead;config.c_cc[VTIME]  = timeoutBetweenBytes;//step 8: set configuration to serial portif(tcsetattr(fd, TCSANOW, &config) != 0){fprintf(stderr, "error@configSerialPort: fail to tcsetattr(fd, TCSANOW, &config)\n");return FAILURE;}//step 9: flush input/output queuesif(tcflush(fd, TCIOFLUSH) != 0){fprintf(stderr, "error@configSerialPort: fail to tcflush(fd, TCIOFLUSH)\n");return FAILURE;}return SUCCESS;}static int  getBaseBaud(int customBaud){if(customBaud <= 0) return 0;if(115200 % customBaud == 0 && 115200 / customBaud < 256) return 115200;if(460800 % customBaud == 0 && 460800 / customBaud < 256) return 460800;if(921600 % customBaud == 0 && 921600 / customBaud < 256) return 921600;if(1500000 % customBaud == 0 && 1500000 / customBaud < 256) return 1500000;return -1;}static void setSerialPortRegister(unsigned short serialPortAddr, int baseBaud, int customBaud){unsigned short enableRegAddr = serialPortAddr + 3;unsigned char DLM = 0x00, DLL = (baseBaud / customBaud) & 0xFF, tmp;//step 1: set high byte of divisor latchswitch(baseBaud){case 115200:  DLM = 0x00; break;case 460800:  DLM = 0x80; break;case 921600:  DLM = 0xC0; break;case 1500000: DLM = 0x20; break;}//step 2: change permission and change registerioperm(enableRegAddr, 1, 1);tmp = inb(enableRegAddr);outb(0x80 | tmp, enableRegAddr);ioperm(serialPortAddr, 2, 1);outb(DLL, serialPortAddr + 0);outb(DLM, serialPortAddr + 1);//step 3: retrieve permissionoutb(tmp, enableRegAddr);ioperm(enableRegAddr, 1, 0);ioperm(serialPortAddr, 2, 0);}static int openSerialPortAtNonStandardBaud(const char* dev, const char* mode, int blocking, const struct Config* pConfig){int customBaud = pConfig->baudRate, baseBaud = getBaseBaud(pConfig->baudRate);//step 0: check if customBaud is supportedif(baseBaud < 0){fprintf(stderr, "error@openSerialPortAtNonStandardBaud: invalid baud rate\n");return -1;}//step 1: open serial portint fd = openSerialPort(dev, mode, blocking);if(fd < 0) return -2;//set hardware controlstruct serial_struct ss;if(ioctl(fd, TIOCGSERIAL, &ss) < 0){fprintf(stderr, "error@openSerialPortAtNonStandardBaud: fail to ioctl(fd, TIOCGSERIAL, &ss)\n");return -3;}ss.flags = ASYNC_SPD_CUST;ss.baud_base = baseBaud;ss.custom_divisor = ss.baud_base / customBaud;//add hardware controlif(ioctl(fd, TIOCSSERIAL, &ss) < 0){fprintf(stderr, "error@openSerialPortAtNonStandardBaud: fail to ioctl(fd, TIOCSSERIAL, &ss)\n");return -4;}if(ioctl(fd, TIOCGSERIAL, &ss) < 0){fprintf(stderr, "error@openSerialPortAtNonStandardBaud: fail to ioctl(fd, TIOCGSERIAL, &ss)\n");return -5;}//step 3: set configurationif(SUCCESS != configurateSerialPort(fd, 38400,//must set baud rate to 38400 to get custom baud pConfig->dataBits, pConfig->parity, pConfig->stopBits, pConfig->minToRead, pConfig->timeoutBetweenBytes)){fprintf(stderr, "error@openSerialPortAtNonStandardBaud: fail to configurateSerialPort(...)\n");return -6;}//step 4: change register to reinterpret 38400setSerialPortRegister(pConfig->baseAddr, baseBaud, customBaud);return fd;}int openAndConfigurateSerialPort(const char* dev, const char* mode, int blocking, const struct Config* pConfig){int fd, type = getBaudRateType(pConfig->baudRate);//check if baud rate supportedif(type < 0){fprintf(stderr, "error@openSerialPort: invalid baud rate\n");return -1;}//check if data bits supportedif(!isSupportedDataBits(pConfig->dataBits)){fprintf(stderr, "error@openSerialPort: invalid data bits\n");return -2;}//check if parity supportedif(!isSupportedParity(pConfig->parity)){fprintf(stderr, "error@openSerialPort: invalid parity\n");return -3;}//check if stop bits supportedif(!isSupportedStopBits(pConfig->stopBits)){fprintf(stderr, "error@openSerialPort: invalid stop bits\n");return -4;}//baud rate is supported nonstandard baud rateif(type == 1){fd = openSerialPortAtNonStandardBaud(dev, mode, blocking, pConfig);if(fd < 0) fprintf(stderr, "error@openSerialPort: fail to openSerialPortAtNonStandardBaud(dev, mode, pConfig)\n");return fd;}//baud rate is standard baud ratefd = openSerialPort(dev, mode, blocking);if(fd < 0){fprintf(stderr, "error@openSerialPort: fail to openSerialPort(dev, mode)\n");return -5;}if(SUCCESS != configurateSerialPort(fd,pConfig->baudRate,pConfig->dataBits,pConfig->parity,pConfig->stopBits,pConfig->minToRead,pConfig->timeoutBetweenBytes)){fprintf(stderr, "error@openSerialPort: fail to configurateSerialPort(...)\n");return -6;}return fd;}int send(int fd, void* frame, int len){int nsent = 0, alreadySent = 0;for(; alreadySent < len; alreadySent += nsent){nsent = write(fd, frame + alreadySent, len - alreadySent);if(nsent <= 0){fprintf(stderr, "error@sendFrame: fail to write(fd, frame + alreadySent, len - alreadySent)\n");break;}}return alreadySent;}static int tread(int fd, void *buf, int maxSize, struct timeval* ptv){int    nfds;    fd_set readfds;    FD_ZERO(&readfds);    FD_SET(fd, &readfds);    nfds = select(fd+1, &readfds, NULL, NULL, ptv);    if(nfds <= 0){    if(nfds == 0) errno = ETIME;        return -1;    }    return read(fd, buf, maxSize);}int treadn(int fd, void *buf, int nbytes, int timeoutSec, int timeoutMicrosec){int nleft;    int nread;    struct timeval tv;    tv.tv_sec  = timeoutSec;    tv.tv_usec = timeoutMicrosec;    nleft = nbytes;    while(nleft > 0){    if((nread = tread(fd, buf, nleft, &tv)) < 0){    if (nleft == nbytes) return -1; /* error, received nothing at all return -1 */            else break; /* error, return amount received so far */        }    else if (nread == 0) break;        nleft -= nread;        buf   += nread;    }    return nbytes - nleft; /* return >= 0 */}int receive(int fd, void* frame, int maxLen){return read(fd, frame, maxLen);}