riscom8.c

讲述linux的初始化过程

		interruptible_sleep_on(&port->close_wait);
		if (port->flags & ASYNC_HUP_NOTIFY)
			return -EAGAIN;
		else
			return -ERESTARTSYS;
	}

	/*
	 * If this is a callout device, then just make sure the normal
	 * device isn't being used.
	 */
	if (tty->driver.subtype == RISCOM_TYPE_CALLOUT) {
		if (port->flags & ASYNC_NORMAL_ACTIVE)
			return -EBUSY;
		if ((port->flags & ASYNC_CALLOUT_ACTIVE) &&
		    (port->flags & ASYNC_SESSION_LOCKOUT) &&
		    (port->session != current->session))
		    return -EBUSY;
		if ((port->flags & ASYNC_CALLOUT_ACTIVE) &&
		    (port->flags & ASYNC_PGRP_LOCKOUT) &&
		    (port->pgrp != current->pgrp))
		    return -EBUSY;
		port->flags |= ASYNC_CALLOUT_ACTIVE;
		return 0;
	}
	
	/*
	 * If non-blocking mode is set, or the port is not enabled,
	 * then make the check up front and then exit.
	 */
	if ((filp->f_flags & O_NONBLOCK) ||
	    (tty->flags & (1 << TTY_IO_ERROR))) {
		if (port->flags & ASYNC_CALLOUT_ACTIVE)
			return -EBUSY;
		port->flags |= ASYNC_NORMAL_ACTIVE;
		return 0;
	}

	if (port->flags & ASYNC_CALLOUT_ACTIVE) {
		if (port->normal_termios.c_cflag & CLOCAL) 
			do_clocal = 1;
	} else {
		if (C_CLOCAL(tty))  
			do_clocal = 1;
	}
	
	/*
	 * Block waiting for the carrier detect and the line to become
	 * free (i.e., not in use by the callout).  While we are in
	 * this loop, info->count is dropped by one, so that
	 * rs_close() knows when to free things.  We restore it upon
	 * exit, either normal or abnormal.
	 */
	retval = 0;
	add_wait_queue(&port->open_wait, &wait);
	cli();
	if (!tty_hung_up_p(filp))
		port->count--;
	sti();
	port->blocked_open++;
	while (1) {
		cli();
		rc_out(bp, CD180_CAR, port_No(port));
		CD = rc_in(bp, CD180_MSVR) & MSVR_CD;
		if (!(port->flags & ASYNC_CALLOUT_ACTIVE))  {
			rc_out(bp, CD180_MSVR, MSVR_RTS);
			bp->DTR &= ~(1u << port_No(port));
			rc_out(bp, RC_DTR, bp->DTR);
		}
		sti();
		set_current_state(TASK_INTERRUPTIBLE);
		if (tty_hung_up_p(filp) ||
		    !(port->flags & ASYNC_INITIALIZED)) {
			if (port->flags & ASYNC_HUP_NOTIFY)
				retval = -EAGAIN;
			else
				retval = -ERESTARTSYS;	
			break;
		}
		if (!(port->flags & ASYNC_CALLOUT_ACTIVE) &&
		    !(port->flags & ASYNC_CLOSING) &&
		    (do_clocal || CD))
			break;
		if (signal_pending(current)) {
			retval = -ERESTARTSYS;
			break;
		}
		schedule();
	}
	current->state = TASK_RUNNING;
	remove_wait_queue(&port->open_wait, &wait);
	if (!tty_hung_up_p(filp))
		port->count++;
	port->blocked_open--;
	if (retval)
		return retval;
	
	port->flags |= ASYNC_NORMAL_ACTIVE;
	return 0;
}	

static int rc_open(struct tty_struct * tty, struct file * filp)
{
	int board;
	int error;
	struct riscom_port * port;
	struct riscom_board * bp;
	unsigned long flags;
	
	board = RC_BOARD(MINOR(tty->device));
	if (board > RC_NBOARD || !(rc_board[board].flags & RC_BOARD_PRESENT))
		return -ENODEV;
	
	bp = &rc_board[board];
	port = rc_port + board * RC_NPORT + RC_PORT(MINOR(tty->device));
	if (rc_paranoia_check(port, tty->device, "rc_open"))
		return -ENODEV;
	
	if ((error = rc_setup_board(bp))) 
		return error;
		
	port->count++;
	tty->driver_data = port;
	port->tty = tty;
	
	if ((error = rc_setup_port(bp, port))) 
		return error;
	
	if ((error = block_til_ready(tty, filp, port)))
		return error;
	
	if ((port->count == 1) && (port->flags & ASYNC_SPLIT_TERMIOS)) {
		if (tty->driver.subtype == RISCOM_TYPE_NORMAL)
			*tty->termios = port->normal_termios;
		else
			*tty->termios = port->callout_termios;
		save_flags(flags); cli();
		rc_change_speed(bp, port);
		restore_flags(flags);
	}

	port->session = current->session;
	port->pgrp = current->pgrp;
	
	return 0;
}

static void rc_close(struct tty_struct * tty, struct file * filp)
{
	struct riscom_port *port = (struct riscom_port *) tty->driver_data;
	struct riscom_board *bp;
	unsigned long flags;
	unsigned long timeout;
	
	if (!port || rc_paranoia_check(port, tty->device, "close"))
		return;
	
	save_flags(flags); cli();
	if (tty_hung_up_p(filp))  {
		restore_flags(flags);
		return;
	}
	
	bp = port_Board(port);
	if ((tty->count == 1) && (port->count != 1))  {
		printk("rc%d: rc_close: bad port count;"
		       " tty->count is 1, port count is %d\n",
		       board_No(bp), port->count);
		port->count = 1;
	}
	if (--port->count < 0)  {
		printk("rc%d: rc_close: bad port count for tty%d: %d\n",
		       board_No(bp), port_No(port), port->count);
		port->count = 0;
	}
	if (port->count)  {
		restore_flags(flags);
		return;
	}
	port->flags |= ASYNC_CLOSING;
	/*
	 * Save the termios structure, since this port may have
	 * separate termios for callout and dialin.
	 */
	if (port->flags & ASYNC_NORMAL_ACTIVE)
		port->normal_termios = *tty->termios;
	if (port->flags & ASYNC_CALLOUT_ACTIVE)
		port->callout_termios = *tty->termios;
	/*
	 * Now we wait for the transmit buffer to clear; and we notify 
	 * the line discipline to only process XON/XOFF characters.
	 */
	tty->closing = 1;
	if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
		tty_wait_until_sent(tty, port->closing_wait);
	/*
	 * At this point we stop accepting input.  To do this, we
	 * disable the receive line status interrupts, and tell the
	 * interrupt driver to stop checking the data ready bit in the
	 * line status register.
	 */
	port->IER &= ~IER_RXD;
	if (port->flags & ASYNC_INITIALIZED) {
		port->IER &= ~IER_TXRDY;
		port->IER |= IER_TXEMPTY;
		rc_out(bp, CD180_CAR, port_No(port));
		rc_out(bp, CD180_IER, port->IER);
		/*
		 * Before we drop DTR, make sure the UART transmitter
		 * has completely drained; this is especially
		 * important if there is a transmit FIFO!
		 */
		timeout = jiffies+HZ;
		while(port->IER & IER_TXEMPTY)  {
			current->state = TASK_INTERRUPTIBLE;
 			schedule_timeout(port->timeout);
			if (time_after(jiffies, timeout))
				break;
		}
	}
	rc_shutdown_port(bp, port);
	if (tty->driver.flush_buffer)
		tty->driver.flush_buffer(tty);
	if (tty->ldisc.flush_buffer)
		tty->ldisc.flush_buffer(tty);
	tty->closing = 0;
	port->event = 0;
	port->tty = 0;
	if (port->blocked_open) {
		if (port->close_delay) {
			current->state = TASK_INTERRUPTIBLE;
			schedule_timeout(port->close_delay);
		}
		wake_up_interruptible(&port->open_wait);
	}
	port->flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CALLOUT_ACTIVE|
			 ASYNC_CLOSING);
	wake_up_interruptible(&port->close_wait);
	restore_flags(flags);
}

static int rc_write(struct tty_struct * tty, int from_user, 
		    const unsigned char *buf, int count)
{
	struct riscom_port *port = (struct riscom_port *)tty->driver_data;
	struct riscom_board *bp;
	int c, total = 0;
	unsigned long flags;
				
	if (rc_paranoia_check(port, tty->device, "rc_write"))
		return 0;
	
	bp = port_Board(port);

	if (!tty || !port->xmit_buf || !tmp_buf)
		return 0;

	if (from_user)
		down(&tmp_buf_sem);

	save_flags(flags);
	while (1) {
		cli();		
		c = MIN(count, MIN(SERIAL_XMIT_SIZE - port->xmit_cnt - 1,
				   SERIAL_XMIT_SIZE - port->xmit_head));
		if (c <= 0)
			break;

		if (from_user) {
			copy_from_user(tmp_buf, buf, c);
			c = MIN(c, MIN(SERIAL_XMIT_SIZE - port->xmit_cnt - 1,
				       SERIAL_XMIT_SIZE - port->xmit_head));
			memcpy(port->xmit_buf + port->xmit_head, tmp_buf, c);
		} else
			memcpy(port->xmit_buf + port->xmit_head, buf, c);
		port->xmit_head = (port->xmit_head + c) & (SERIAL_XMIT_SIZE-1);
		port->xmit_cnt += c;
		restore_flags(flags);
		buf += c;
		count -= c;
		total += c;
	}
	if (from_user)
		up(&tmp_buf_sem);
	if (port->xmit_cnt && !tty->stopped && !tty->hw_stopped &&
	    !(port->IER & IER_TXRDY)) {
		port->IER |= IER_TXRDY;
		rc_out(bp, CD180_CAR, port_No(port));
		rc_out(bp, CD180_IER, port->IER);
	}
	restore_flags(flags);
	return total;
}

static void rc_put_char(struct tty_struct * tty, unsigned char ch)
{
	struct riscom_port *port = (struct riscom_port *)tty->driver_data;
	unsigned long flags;

	if (rc_paranoia_check(port, tty->device, "rc_put_char"))
		return;

	if (!tty || !port->xmit_buf)
		return;

	save_flags(flags); cli();
	
	if (port->xmit_cnt >= SERIAL_XMIT_SIZE - 1) {
		restore_flags(flags);
		return;
	}

	port->xmit_buf[port->xmit_head++] = ch;
	port->xmit_head &= SERIAL_XMIT_SIZE - 1;
	port->xmit_cnt++;
	restore_flags(flags);
}

static void rc_flush_chars(struct tty_struct * tty)
{
	struct riscom_port *port = (struct riscom_port *)tty->driver_data;
	unsigned long flags;
				
	if (rc_paranoia_check(port, tty->device, "rc_flush_chars"))
		return;
	
	if (port->xmit_cnt <= 0 || tty->stopped || tty->hw_stopped ||
	    !port->xmit_buf)
		return;

	save_flags(flags); cli();
	port->IER |= IER_TXRDY;
	rc_out(port_Board(port), CD180_CAR, port_No(port));
	rc_out(port_Board(port), CD180_IER, port->IER);
	restore_flags(flags);
}

static int rc_write_room(struct tty_struct * tty)
{
	struct riscom_port *port = (struct riscom_port *)tty->driver_data;
	int	ret;
				
	if (rc_paranoia_check(port, tty->device, "rc_write_room"))
		return 0;

	ret = SERIAL_XMIT_SIZE - port->xmit_cnt - 1;
	if (ret < 0)
		ret = 0;
	return ret;
}

static int rc_chars_in_buffer(struct tty_struct *tty)
{
	struct riscom_port *port = (struct riscom_port *)tty->driver_data;
				
	if (rc_paranoia_check(port, tty->device, "rc_chars_in_buffer"))
		return 0;
	
	return port->xmit_cnt;
}

static void rc_flush_buffer(struct tty_struct *tty)
{
	struct riscom_port *port = (struct riscom_port *)tty->driver_data;
	unsigned long flags;
				
	if (rc_paranoia_check(port, tty->device, "rc_flush_buffer"))
		return;

	save_flags(flags); cli();
	port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
	restore_flags(flags);
	
	wake_up_interruptible(&tty->write_wait);
	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
	    tty->ldisc.write_wakeup)
		(tty->ldisc.write_wakeup)(tty);
}

static int rc_get_modem_info(struct riscom_port * port, unsigned int *value)
{
	struct riscom_board * bp;
	unsigned char status;
	unsigned int result;
	unsigned long flags;

	bp = port_Board(port);
	save_flags(flags); cli();
	rc_out(bp, CD180_CAR, port_No(port));
	status = rc_in(bp, CD180_MSVR);
	result = rc_in(bp, RC_RI) & (1u << port_No(port)) ? 0 : TIOCM_RNG;
	restore_flags(flags);
	result |= ((status & MSVR_RTS) ? TIOCM_RTS : 0)
		| ((status & MSVR_DTR) ? TIOCM_DTR : 0)
		| ((status & MSVR_CD)  ? TIOCM_CAR : 0)
		| ((status & MSVR_DSR) ? TIOCM_DSR : 0)
		| ((status & MSVR_CTS) ? TIOCM_CTS : 0);
	put_user(result, value);
	return 0;
}

static int rc_set_modem_info(struct riscom_port * port, unsigned int cmd,
			     unsigned int *value)
{
	int error;
	unsigned int arg;
	unsigned long flags;
	struct riscom_board *bp = port_Board(port);

	error = get_user(arg, value);
	if (error) 
		return error;
	switch (cmd) {
	 case TIOCMBIS: 
		if (arg & TIOCM_RTS) 
			port->MSVR |= MSVR_RTS;
		if (arg & TIOCM_DTR)
			bp->DTR &= ~(1u << port_No(port));
		break;
	case TIOCMBIC:
		if (arg & TIOCM_RTS)
			port->MSVR &= ~MSVR_RTS;
		if (arg & TIOCM_DTR)
			bp->DTR |= (1u << port_No(port));
		break;
	case TIOCMSET:
		port->MSVR = (arg & TIOCM_RTS) ? (port->MSVR | MSVR_RTS) : 
					         (port->MSVR & ~MSVR_RTS);
		bp->DTR = arg & TIOCM_DTR ? (bp->DTR &= ~(1u << port_No(port))) :
					    (bp->DTR |=  (1u << port_No(port)));
		break;
	 default:
		return -EINVAL;
	}
	save_flags(flags); cli();
	rc_out(bp, CD180_CAR, port_No(port));
	rc_out(bp, CD180_MSVR, port->MSVR);
	rc_out(bp, RC_DTR, bp->DTR);
	restore_flags(flags);
	return 0;
}

static inline void rc_send_break(struct riscom_port * port, unsigned long length)
{
	struct riscom_board *bp = port_Board(port);
	unsigned long flags;
	
	save_flags(flags); cli();
	port->break_length = RISCOM_TPS / HZ * length;
	port->COR2 |= COR2_ETC;
	port->IER  |= IER_TXRDY;
	rc_out(bp, CD180_CAR, port_No(port));
	rc_out(bp, CD180_COR2, port->COR2);
	rc_out(bp, CD180_IER, port->IER);
	rc_wait_CCR(bp);
	rc_out(bp, CD180_CCR, CCR_CORCHG2);
	rc_wait_CCR(bp);
	restore_flags(flags);
}

static inline int rc_set_serial_info(struct riscom_port * port,
				     struct serial_struct * newinfo)
{
	struct serial_struct tmp;
	struct riscom_board *bp = port_Board(port);
	int change_speed;
	unsigned long flags;
	int error;
	
	error = verify_area(VERIFY_READ, (void *) newinfo, sizeof(tmp));
	if (error)
		return error;
	copy_from_user(&tmp, newinfo, sizeof(tmp));
	
#if 0	
	if ((tmp.irq != bp->irq) ||
	    (tmp.port != bp->base) ||
	    (tmp.type != PORT_CIRRUS) ||
	    (tmp.baud_base != (RC_OSCFREQ + CD180_TPC/2) / CD180_TPC) ||
	    (tmp.custom_divisor != 0) ||
	    (tmp.xmit_fifo_size != CD180_NFIFO) ||