Linux：TTY串口接收中断

Linux的串口接收中断一般都是使能的，无论是否是DMA接收。

当串口接收到数据的时候，会调用 stm32_usart_push_buffer_dma函数。在这个函数内部向用户层发送信号，然后就可以调用read方法，读取数据了。从而避免循环读取数据。

n_tty.c

// application pid, application use ioctl method to set this value
int app_pid_ttySTM2 = 0;typedef enum{IOCTL_SET_APP_PID = 0x111,
} MODULE_CMD;static int n_tty_ioctl(struct tty_struct *tty, struct file *file,unsigned int cmd, unsigned long arg)
{struct n_tty_data *ldata = tty->disc_data;int retval;printk(KERN_INFO "gpio_XXXX_ioctl:%s cmd=0x%x,arg=0x%lx\n", __func__, cmd, arg);switch (cmd) {case TIOCOUTQ:return put_user(tty_chars_in_buffer(tty), (int __user *) arg);case TIOCINQ:down_write(&tty->termios_rwsem);if (L_ICANON(tty) && !L_EXTPROC(tty))retval = inq_canon(ldata);elseretval = read_cnt(ldata);up_write(&tty->termios_rwsem);return put_user(retval, (unsigned int __user *) arg);case IOCTL_SET_APP_PID:{if(tty->index == 2){if(copy_from_user(&app_pid_ttySTM2, (int *)arg, sizeof(int))){return -EFAULT;}}return 0;}default:return n_tty_ioctl_helper(tty, file, cmd, arg);}
}

stm32-usart.c

#define SIGETX 44static void stm32_usart_push_buffer_dma(struct uart_port *port,unsigned int dma_size)
{struct stm32_port *stm32_port = to_stm32_port(port);struct tty_port *ttyport = &stm32_port->port.state->port;unsigned char *dma_start;int dma_count;struct kernel_siginfo info;struct task_struct *task = NULL;dma_start = stm32_port->rx_buf + (RX_BUF_L - stm32_port->last_res);dma_count = tty_insert_flip_string(ttyport, dma_start, dma_size);port->icount.rx += dma_count;stm32_port->last_res -= dma_count;if (stm32_port->last_res == 0)stm32_port->last_res = RX_BUF_L;if (app_pid_ttySTM2 == 0){printk(KERN_ALERT "XXXX_NOTIFIER: gpio_XXXX_handler not set user pid\n");return ;}//Sending signal to appmemset(&info, 0, sizeof(struct kernel_siginfo));info.si_signo = SIGETX;info.si_code = 0;info.si_int = 1234;printk(KERN_INFO "gpio_XXXX_handler Interrupt received from GPIO XXXX pin\n");rcu_read_lock();task = pid_task(find_vpid(app_pid_ttySTM2), PIDTYPE_PID);rcu_read_unlock();if (task == NULL) {printk(KERN_ALERT "XXXX_NOTIFIER: get_current failed\n");return;}else{printk(KERN_INFO "Sending signal to app\n");if(send_sig_info(SIGETX, &info, task) < 0) {printk(KERN_ALERT "gpio_XXXX_handler Unable to send signal\n");}}
}

应用程序：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include <getopt.h>
#include <string.h>
#include <signal.h>
#include <pthread.h>
#include <stdbool.h>#define FALSE 0
#define TRUE 1char *recchr="We received:\"";void print_usage();int speed_arr[] = {B921600, B460800, B230400, B115200, B57600, B38400, B19200,B9600, B4800, B2400, B1200, B300,
};int name_arr[] = {921600, 460800, 230400, 115200, 57600, 38400,  19200,9600,  4800,  2400,  1200,  300,
};#define SIGETX 44
int check = 0;typedef enum{IOCTL_SET_APP_PID = 0x111,
} APP_CMD;bool readyReadFlag = FALSE;void sig_event_handler(int n, siginfo_t *info, void *unused)
{printf ("sig_event_handler Received signal from kernel");if (n == SIGETX) {check = info->si_int;printf ("Received signal from kernel : Value =  %u\n", check);readyReadFlag = TRUE;}
}void set_speed(int fd, int speed)
{int   i;int   status;struct termios   Opt;tcgetattr(fd, &Opt);for ( i= 0;  i < sizeof(speed_arr) / sizeof(int);  i++) {if  (speed == name_arr[i])  {tcflush(fd, TCIOFLUSH);cfsetispeed(&Opt, speed_arr[i]);cfsetospeed(&Opt, speed_arr[i]);status = tcsetattr(fd, TCSANOW, &Opt);if  (status != 0)perror("tcsetattr fd1");return;}tcflush(fd,TCIOFLUSH);}if (i == 12){printf("\tSorry, please set the correct baud rate!\n\n");print_usage(stderr, 1);}
}
/**@brief   璁剧疆涓插彛鏁版嵁浣嶏紝鍋滄浣嶅拰鏁堥獙浣�*@param  fd     绫诲瀷  int  鎵撳紑鐨勪覆鍙ｆ枃浠跺彞鏌�**@param  databits 绫诲瀷  int 鏁版嵁浣�   鍙栧�� 涓� 7 鎴栬��8**@param  stopbits 绫诲瀷  int 鍋滄浣�   鍙栧�间负 1 鎴栬��2**@param  parity  绫诲瀷  int  鏁堥獙绫诲瀷 鍙栧�间负N,E,O,,S
*/
int set_Parity(int fd,int databits,int stopbits,int parity)
{struct termios options;if  ( tcgetattr( fd,&options)  !=  0) {perror("SetupSerial 1");return(FALSE);}options.c_cflag &= ~CSIZE ;switch (databits) /*璁剧疆鏁版嵁浣嶆暟*/ {case 7:options.c_cflag |= CS7;break;case 8:options.c_cflag |= CS8;break;default:fprintf(stderr,"Unsupported data size\n");return (FALSE);}switch (parity) {case 'n':case 'N':options.c_cflag &= ~PARENB;   /* Clear parity enable */options.c_iflag &= ~INPCK;     /* Enable parity checking */break;case 'o':case 'O':options.c_cflag |= (PARODD | PARENB);  /* 璁剧疆涓哄鏁堥獙*/options.c_iflag |= INPCK;             /* Disnable parity checking */break;case 'e':case 'E':options.c_cflag |= PARENB;     /* Enable parity */options.c_cflag &= ~PARODD;   /* 杞崲涓哄伓鏁堥獙*/options.c_iflag |= INPCK;       /* Disnable parity checking */break;case 'S':case 's':  /*as no parity*/options.c_cflag &= ~PARENB;options.c_cflag &= ~CSTOPB;break;default:fprintf(stderr,"Unsupported parity\n");return (FALSE);}/* 璁剧疆鍋滄浣�*/switch (stopbits) {case 1:options.c_cflag &= ~CSTOPB;break;case 2:options.c_cflag |= CSTOPB;break;default:fprintf(stderr,"Unsupported stop bits\n");return (FALSE);}/* Set input parity option */if (parity != 'n')options.c_iflag |= INPCK;options.c_cc[VTIME] = 150; // 15 secondsoptions.c_cc[VMIN] = 0;//options.c_lflag &= ~(ECHO | ICANON);options.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR | ICRNL | IXON);options.c_oflag &= ~OPOST;options.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);options.c_cflag &= ~(CSIZE | PARENB);tcflush(fd,TCIFLUSH); /* Update the options and do it NOW */if (tcsetattr(fd,TCSANOW,&options) != 0) {perror("SetupSerial 3");return (FALSE);}return (TRUE);
}/***@breif 鎵撳紑涓插彛
*/
int OpenDev(char *Dev)
{int fd = open( Dev, O_RDWR );         //| O_NOCTTY | O_NDELAYif (-1 == fd) { /*璁剧疆鏁版嵁浣嶆暟*/perror("Can't Open Serial Port");return -1;} elsereturn fd;
}/* The name of this program */
const char * program_name;/* Prints usage information for this program to STREAM (typically* stdout or stderr), and exit the program with EXIT_CODE. Does not* return.*/void print_usage (FILE *stream, int exit_code)
{fprintf(stream, "Usage: %s option [ dev... ] \n", program_name);fprintf(stream,"\t-h  --help     Display this usage information.\n""\t-d  --device   The device ttyS[0-3] or ttySCMA[0-1]\n""\t-b  --baudrate Set the baud rate you can select\n""\t               [230400, 115200, 57600, 38400, 19200, 9600, 4800, 2400, 1200, 300]\n""\t-s  --string   Write the device data\n");exit(exit_code);
}/**@breif  main()*/
int main(int argc, char *argv[])
{int  fd, next_option, havearg = 0;char *device;int i=0,j=0;int nread;           /* Read the counts of data */char buff[512];        /* Recvice data buffer */pid_t pid;int app_pid;struct sigaction act;//char *xmit = "1234567890"; /* Default send data */char *xmit = "0x11 0x12 0x13 0x14 0x15 0x16 0x17 0x18 0x19 0x20"; /* Default send data */char xmit_data[15] = {0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25};int speed, send_mode = 0;const char *const short_options = "hd:s:b:m:";const struct option long_options[] = {{ "help",   0, NULL, 'h'},{ "device", 1, NULL, 'd'},{ "string", 1, NULL, 's'},{ "baudrate", 1, NULL, 'b'},{ "send/recv mode", 0, NULL, 'm'},{ NULL,     0, NULL, 0  }};/* install custom signal handler */sigemptyset(&act.sa_mask);act.sa_flags = SA_NODEFER;act.sa_sigaction = sig_event_handler;sigaction(SIGETX, &act, NULL);printf("Installed signal handler for SIGETX = %d\n", SIGETX);app_pid = getpid();program_name = argv[0];do {next_option = getopt_long (argc, argv, short_options, long_options, NULL);switch (next_option) {case 'h':print_usage (stdout, 0);case 'd':device = optarg;havearg = 1;break;case 'b':speed = atoi(optarg);break;case 's':xmit = optarg;havearg = 1;break;case 'm':send_mode = atoi(optarg);break;case -1:if (havearg)  break;case '?':print_usage (stderr, 1);default:abort ();}}while(next_option != -1);sleep(1);fd = OpenDev(device);if (fd > 0) {set_speed(fd, speed);} else {fprintf(stderr, "Error opening %s: %s\n", device, strerror(errno));exit(1);}if (set_Parity(fd,8,1,'N')== FALSE) {fprintf(stderr, "Set Parity Error\n");close(fd);exit(1);}ioctl(fd, IOCTL_SET_APP_PID, &app_pid);#if 0pid = fork();if (pid < 0) {fprintf(stderr, "Error in fork!\n");} else if (pid == 0){
#endifif (send_mode){while(1) {printf("%s SEND: %s\n",device, xmit);//write(fd, xmit, strlen(xmit));write(fd, xmit_data, sizeof(xmit_data));sleep(1);i++;}}else {while(1) {if(readyReadFlag){printf("Start to read. \n");nread = read(fd, buff, sizeof(buff));if (nread > 0) {printf("RECV nread = %d\n", nread);for(int id = 0; id < nread; id++){printf("RECV[%d]: %d\n", id, buff[id]);}buff[nread] = '\0';//printf("%s RECV[%d]: %s\n", device, nread, buff);}readyReadFlag = FALSE;}sleep(1);}}close(fd);exit(0);
}

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