USB状态监听

1 编译监听usb状态文件

cd doc/开发使用说明/USB使用说明文档/USB状态监听/

../../../../buildroot/buildroot/output/host/bin/mips-linux-gnu-gcc usb_state.c -o  usb_state

2 usb_state 命令介绍

usb 状态：not attached、attached、powered、reconnecting、unauthenticated、default、addresssed、configured、suspended

./usb_state <udc_path> <状态>

./usb_state  /sys/class/udc/13500000.otg "suspended"

注意:udc_path 平台不同路径会有差异,x1000平台udc_path路径为/sys/class/udc/dwc2/,x2000平台udc_path路径为/sys/class/udc/13500000.otg

3 相关源码

/*
 功能：监听usb状态
*/
int main(int argc, char *argv[])
{
    int fd;
    int fd1;
    fd_set efds;
    int ret, len;
    char buf[128];
    char *usb_state = NULL;
    const char *udc_path = NULL;

    char state_buf[128];

    prg_name = argv[0];

    if (argc < 2)
        usage(-1);

    udc_path = argv[1];

    if (argc > 2)
        usb_state = argv[2];

    memset(state_buf, 0, sizeof(state_buf));
    sprintf(state_buf, "%s/state", udc_path);
    fd = open(state_buf, O_RDONLY);
    if (fd < 0) {
        printf("open %s fail\n", state_buf);
        return -1;
    }

    memset(state_buf, 0, sizeof(state_buf));
    sprintf(state_buf, "%s/power_type", udc_path);
    fd1 = open(state_buf, O_RDONLY);
    if (fd1 < 0) {
        printf("open %s fail\n", state_buf);
    }

    while (1) {
        FD_ZERO(&efds);
        FD_SET(fd, &efds);

        ret = select(fd + 1, NULL, NULL, &efds, NULL);
        if (ret == -1) {
            fprintf(stderr, "select error\n");
            break;
        }

        if (FD_ISSET(fd, &efds)) {
            if (fd1 >= 0) {
                memset(buf, 0, sizeof(buf));
                len = read(fd1, buf, sizeof(buf));
                lseek(fd1, 0, SEEK_SET);
                printf("usb power : %s\n", buf);
            }

            memset(buf, 0, sizeof(buf));
            len = read(fd, buf, sizeof(buf));
            lseek(fd, 0, SEEK_SET);
            printf("usb state : %s\n", buf);

            if (usb_state) {
                ret = strncmp(buf, usb_state, len - 1);
                if (ret == 0)
                    break;
            }

        }
    }

    close(fd);

    if (fd1 >= 0)
        close(fd1);

    return 0;
}