linux uart驱动及应用

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1、#defineTTY_MAJOR4#defineTTYAUX_MAJOR5Tty:终端设备的统称。一般分为：控制台、串口和pty./dev/ttySn:串行端口终端（串口），串行端口被看做字符设备。4:66（设备号）->../../devices/platform/serial8250/tty/ttyS24:67->../../devices/platform/serial8250/tty/ttyS34:68->../../devices/platform/serial8250/tty/ttyS4echotest>/dev/ttyS2

2、可接串口来测试ttyS2。Pty:pseudotty虚拟（伪）终端pts(pseudo-terminalslave)与ptmx(pseudo-terminalmaster)配合使用实现pty。打开一个伪terminal,那么将会在devpts文件系统/dev/pts下创建一个对应的pts字符文件。通过tty命令（或者whoami）查看当前终端，可以看出此伪terminal对应着pts3。再打开一个伪terminal：此伪terminal对应着pts4.两个终端间传输信息：/dev/tty:就是当前使用的终端。设备号：5:0tty可以是

3、pts3，也可以是tty1。控制台终端：tty0:代表当前使用的控制台终端。设备号4:0.Ubuntu下：图像界面下通过Ctrl+Alt+F1—F6可以切换到tty1到tty6。Ctrl+Alt+F7切会图像界面。Pts3发送到tty1。/dev/console是指向当前console。设备号5:1----------------------------------------------------------------------------------------------------------Tty核心：structtt

4、y_driver*alloc_tty_driver(intlines){structtty_driver*driver;driver=kzalloc(sizeof(structtty_driver),GFP_KERNEL);if(driver){kref_init(&driver->kref);driver->magic=TTY_DRIVER_MAGIC;driver->num=lines;（次设备个数）/*laterwe'llmoveallocationoftableshere*/}returndriver;}//分配一个结构体tt

5、y_driver，初始化其magic、num。inttty_register_driver(structtty_driver*driver){if(!(driver->flags&TTY_DRIVER_DEVPTS_MEM)&&driver->num){p=kzalloc(driver->num*2*sizeof(void*),GFP_KERNEL);}if(!driver->major){error=alloc_chrdev_region(&dev,driver->minor_start,driver->num,driver->na

6、me);}else{dev=MKDEV(driver->major,driver->minor_start);error=register_chrdev_region(dev,driver->num,driver->name);}//如果没有指定主设备号，则分配并注册，否则直接注册设备号。if(p){driver->ttys=(structtty_struct**)p;driver->termios=(structktermios**)(p+driver->num);}else{driver->ttys=NULL;driver->te

7、rmios=NULL;}cdev_init(&driver->cdev,&tty_fops);//初始化设备操作函数集。driver->cdev.owner=driver->owner;error=cdev_add(&driver->cdev,dev,driver->num);//注册字符设备。mutex_lock(&tty_mutex);list_add(&driver->tty_drivers,&tty_drivers);//此driver->tty_drivers加到链表tty_drivers上mutex_unlock(&tty

8、_mutex);if(!(driver->flags&TTY_DRIVER_DYNAMIC_DEV)){for(i=0;inum;i++){d=tty_register_device(driver,i,