int uart_register_driver(struct uart_driver *drv)

drivers/tty/serial/serial_core.c

/**

 *    uart_register_driver - register a driver with the uart core layer
 *    @drv: low level driver structure
 *
 *    Register a uart driver with the core driver.  We in turn register
 *    with the tty layer, and initialise the core driver per-port state.
 *
 *    We have a proc file in /proc/tty/driver which is named after the
 *    normal driver.
 *
 *    drv->port should be NULL, and the per-port structures should be
 *    registered using uart_add_one_port after this call has succeeded.

 */

int uart_register_driver(struct uart_driver *drv)
{
    struct tty_driver *normal;
    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);    //分配記憶體
    if (!drv->state)
        goto out;

    normal = alloc_tty_driver(drv->nr);        //分配tty驅動
    if (!normal)
        goto out_kfree;

    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);    //設定tty函數集

    /*
     * Initialise the UART state(s).
     */
    for (i = 0; i < drv->nr; i++) {
        struct uart_state *state = drv->state + i;
        struct tty_port *port = &state->port;

        tty_port_init(port);
        port->ops = &uart_port_ops;
        port->close_delay     = 500;    /* .5 seconds */
        port->closing_wait    = 30000;    /* 30 seconds */
        tasklet_init(&state->tlet, uart_tasklet_action,
                 (unsigned long)state);
    }

    retval = tty_register_driver(normal);        //註冊tty驅動
    if (retval >= 0)
        return retval;

    put_tty_driver(normal);
out_kfree:
    kfree(drv->state);
out:
    return -ENOMEM;
}