serial 架构分析

一、首先看一下uart_register_driver();

int uart_register_driver(struct uart_driver *drv)

{

     struct tty_driver *normal = NULL;

     int i, retval;

 

     BUG_ON(drv->state);

 

     /*

      * Maybe we should be using a slab cache for this, especially if

      * we have a large number of ports to handle.

      */

     drv->state = kzalloc(sizeof(struct uart_state) * drv->nr, GFP_KERNEL);

     retval = -ENOMEM;

     if (!drv->state)

         goto out;

 

     normal  = alloc_tty_driver(drv->nr);

     if (!normal)

         goto out;

 

     drv->tty_driver = normal;

 

     normal->owner      = drv->owner;

     normal->driver_name    = drv->driver_name;

     normal->name       = drv->dev_name;

     normal->major      = drv->major;

     normal->minor_start    = drv->minor;

     normal->type       = TTY_DRIVER_TYPE_SERIAL;

     normal->subtype        = SERIAL_TYPE_NORMAL;

     normal->init_termios   = tty_std_termios;

     normal->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;

     normal->init_termios.c_ispeed = normal->init_termios.c_ospeed = 9600;

     normal->flags      = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;

     normal->driver_state    = drv;

     tty_set_operations(normal, &uart_ops);

 

     /*

      * Initialise the UART state(s).

      */

     for (i = 0; i < drv->nr; i++) {

         struct uart_state *state = drv->state + i;

 

         state->close_delay     = 500;    /* .5 seconds */

         state->closing_wait    = 30000;  /* 30 seconds */

 

         mutex_init(&state->mutex);

     }

 

     retval = tty_register_driver(normal);

 out:

     if (retval < 0) {

         put_tty_driver(normal);

         kfree(drv->state);

     }

     return retval;

}
  这里的注册了drv->nr个设备节点，主设备号为drv->major，从设备号依次从drv->minor，
tty_set_operations(normal, &uart_ops)，对tty_driver操作集赋值，然后设置每个设备状态，
最后调用tty_register_driver，注册为tty设备驱动。
二、 uart_port
      调用uart_add_one_port();
     uart_port是具体设备的代表