core.c

IXP425 平台下嵌入式LINUX的串口的驱动程序

{
	struct serial_struct new_serial;
	struct uart_state *state = info->state;
	struct uart_port *port = info->port;
	unsigned long new_port;
	unsigned int change_irq, change_port, old_flags;
	unsigned int old_custom_divisor;
	int retval = 0;

	if (copy_from_user(&new_serial, newinfo, sizeof(new_serial)))
		return -EFAULT;

	new_port = new_serial.port;
	if (HIGH_BITS_OFFSET)
		new_port += (unsigned long) new_serial.port_high << HIGH_BITS_OFFSET;

	new_serial.irq = irq_cannonicalize(new_serial.irq);

	/*
	 * This semaphore protects state->count.  It is also
	 * very useful to prevent opens.  Also, take the
	 * port configuration semaphore to make sure that a
	 * module insertion/removal doesn't change anything
	 * under us.
	 */
	down(&port_sem);
	down(&state->count_sem);

	change_irq  = new_serial.irq != port->irq;

	/*
	 * Since changing the 'type' of the port changes its resource
	 * allocations, we should treat type changes the same as
	 * IO port changes.
	 */
	change_port = new_port != port->iobase ||
		      (unsigned long)new_serial.iomem_base != port->mapbase ||
		      new_serial.hub6 != port->hub6 ||
		      new_serial.io_type != port->iotype ||
		      new_serial.iomem_reg_shift != port->regshift ||
		      new_serial.type != port->type;

	old_flags = port->flags;
	old_custom_divisor = state->custom_divisor;

	if (!capable(CAP_SYS_ADMIN)) {
		retval = -EPERM;
		if (change_irq || change_port ||
		    (new_serial.baud_base != port->uartclk / 16) ||
		    (new_serial.close_delay != state->close_delay) ||
		    (new_serial.closing_wait != state->closing_wait) ||
		    (new_serial.xmit_fifo_size != port->fifosize) ||
		    ((new_serial.flags & ~ASYNC_USR_MASK) !=
		     (port->flags & ~ASYNC_USR_MASK)))
			goto exit;
		port->flags = ((port->flags & ~ASYNC_USR_MASK) |
			       (new_serial.flags & ASYNC_USR_MASK));
		info->flags = ((info->flags & ~ASYNC_USR_MASK) |
			       (new_serial.flags & ASYNC_USR_MASK));
		state->custom_divisor = new_serial.custom_divisor;
		goto check_and_exit;
	}

	/*
	 * Ask the low level driver to verify the settings.
	 */
	if (port->ops->verify_port)
		retval = port->ops->verify_port(port, &new_serial);

	if ((new_serial.irq >= NR_IRQS) || (new_serial.irq < 0) ||
	    (new_serial.baud_base < 9600))
		retval = -EINVAL;

	if (retval)
		goto exit;

	if (change_port || change_irq) {
		retval = -EBUSY;

		/*
		 * Make sure that we are the sole user of this port.
		 */
		if (state->count > 1)
			goto exit;

		/*
		 * We need to shutdown the serial port at the old
		 * port/type/irq combination.
		 */
		uart_shutdown(info);
	}

	if (change_port) {
		unsigned long old_iobase, old_mapbase;
		unsigned int old_type, old_iotype, old_hub6, old_shift;

		old_iobase = port->iobase;
		old_mapbase = port->mapbase;
		old_type = port->type;
		old_hub6 = port->hub6;
		old_iotype = port->iotype;
		old_shift = port->regshift;

		/*
		 * Free and release old regions
		 */
		if (old_type != PORT_UNKNOWN)
			port->ops->release_port(port);

		port->iobase = new_port;
		port->type = new_serial.type;
		port->hub6 = new_serial.hub6;
		port->iotype = new_serial.io_type;
		port->regshift = new_serial.iomem_reg_shift;
		port->mapbase = (unsigned long)new_serial.iomem_base;

		/*
		 * Claim and map the new regions
		 */
		if (port->type != PORT_UNKNOWN)
			retval = port->ops->request_port(port);

		/*
		 * If we fail to request resources for the
		 * new port, try to restore the old settings.
		 */
		if (retval && old_type != PORT_UNKNOWN) {
			port->iobase = old_iobase;
			port->type = old_type;
			port->hub6 = old_hub6;
			port->iotype = old_iotype;
			port->regshift = old_shift;
			port->mapbase = old_mapbase;
			retval = port->ops->request_port(port);
			/*
			 * If we failed to restore the old settings,
			 * we fail like this.
			 */
			if (retval)
				port->type = PORT_UNKNOWN;

			/*
			 * We failed anyway.
			 */
			retval = -EBUSY;
		}
	}

	port->irq  = new_serial.irq;
	port->uartclk = new_serial.baud_base * 16;
	port->flags = ((port->flags & ~ASYNC_FLAGS) |
			(new_serial.flags & ASYNC_FLAGS));
	info->flags = ((port->flags & ~ASYNC_INTERNAL_FLAGS) |
		       (info->flags & ASYNC_INTERNAL_FLAGS));
	state->custom_divisor = new_serial.custom_divisor;
	state->close_delay = new_serial.close_delay * HZ / 100;
	state->closing_wait = new_serial.closing_wait * HZ / 100;
	info->tty->low_latency = (info->flags & ASYNC_LOW_LATENCY) ? 1 : 0;
	port->fifosize = new_serial.xmit_fifo_size;

check_and_exit:
	retval = 0;
	if (port->type == PORT_UNKNOWN)
		goto exit;
	if (info->flags & ASYNC_INITIALIZED) {
		if (((old_flags & info->flags) & ASYNC_SPD_MASK) ||
		    old_custom_divisor != state->custom_divisor) {
			uart_update_altspeed(info);
			uart_change_speed(info, NULL);
		}
	} else
		retval = uart_startup(info);
exit:
	up(&state->count_sem);
	up(&port_sem);
	return retval;
}


/*
 * uart_get_lsr_info - get line status register info
 */
static int uart_get_lsr_info(struct uart_info *info, unsigned int *value)
{
	u_int result;
	unsigned long flags;

	spin_lock_irqsave(&info->lock, flags);
	result = info->ops->tx_empty(info->port);
	spin_unlock_irqrestore(&info->lock, flags);

	/*
	 * If we're about to load something into the transmit
	 * register, we'll pretend the transmitter isn't empty to
	 * avoid a race condition (depending on when the transmit
	 * interrupt happens).
	 */
	if (info->port->x_char ||
	    ((CIRC_CNT(info->xmit.head, info->xmit.tail,
		       UART_XMIT_SIZE) > 0) &&
	     !info->tty->stopped && !info->tty->hw_stopped))
		result &= ~TIOCSER_TEMT;
	
	return put_user(result, value);
}

static int uart_get_modem_info(struct uart_info *info, unsigned int *value)
{
	unsigned int result = info->mctrl;

	result |= info->ops->get_mctrl(info->port);

	return put_user(result, value);
}

static int uart_set_modem_info(struct uart_info *info, unsigned int cmd,
			  unsigned int *value)
{
	unsigned int arg, old;
	int ret = 0;

	if (get_user(arg, value))
		return -EFAULT;

	spin_lock_irq(&info->lock);
	old = info->mctrl;
	switch (cmd) {
	case TIOCMBIS:	info->mctrl |= arg;	break;
	case TIOCMBIC:	info->mctrl &= ~arg;	break;
	case TIOCMSET:	info->mctrl = arg;	break;
	default:	ret = -EINVAL;		break;
	}
	if (old != info->mctrl)
		info->ops->set_mctrl(info->port, info->mctrl);
	spin_unlock_irq(&info->lock);
	return ret;
}

static void uart_break_ctl(struct tty_struct *tty, int break_state)
{
	struct uart_info *info = tty->driver_data;
	unsigned long flags;

	if (info->port->type != PORT_UNKNOWN) {
		spin_lock_irqsave(&info->lock, flags);
		info->ops->break_ctl(info->port, break_state);
		spin_unlock_irqrestore(&info->lock, flags);
	}
}

static int uart_do_autoconfig(struct uart_info *info)
{
	struct uart_port *port = info->port;
	int flags, ret;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	/*
	 * Take the 'count' lock.  This prevents count
	 * from incrementing, and hence any extra opens
	 * of the port while we're auto-configging.
	 */
	down(&info->state->count_sem);

	ret = -EBUSY;
	if (info->state->count == 1) {
		uart_shutdown(info);

		/*
		 * If we already have a port type configured,
		 * we must release its resources.
		 */
		if (port->type != PORT_UNKNOWN)
			port->ops->release_port(port);

		flags = UART_CONFIG_TYPE;
		if (port->flags & ASYNC_AUTO_IRQ)
			flags |= UART_CONFIG_IRQ;

		/*
		 * This will claim the ports resources if
		 * a port is found.
		 */
		port->ops->config_port(port, flags);

		ret = uart_startup(info);
	}
	up(&info->state->count_sem);
	return ret;
}

/*
 * Called from userspace.  We can use spin_lock_irq() here.
 */
static int uart_ioctl(struct tty_struct *tty, struct file *file,
			   unsigned int cmd, unsigned long arg)
{
	struct uart_info *info = tty->driver_data;
	struct uart_icount cprev, cnow;
	struct serial_icounter_struct icount;
	int ret = -ENOIOCTLCMD;

	if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
	    (cmd != TIOCSERCONFIG) && (cmd != TIOCSERGSTRUCT) &&
	    (cmd != TIOCMIWAIT) && (cmd != TIOCGICOUNT)) {
		if (tty->flags & (1 << TTY_IO_ERROR))
			return -EIO;
	}

	switch (cmd) {
		case TIOCMGET:
			ret = uart_get_modem_info(info, (unsigned int *)arg);
			break;

		case TIOCMBIS:
		case TIOCMBIC:
		case TIOCMSET:
			ret = uart_set_modem_info(info, cmd,
						  (unsigned int *)arg);
			break;

		case TIOCGSERIAL:
			ret = uart_get_info(info, (struct serial_struct *)arg);
			break;

		case TIOCSSERIAL:
			ret = uart_set_info(info, (struct serial_struct *)arg);
			break;

		case TIOCSERCONFIG:
			ret = uart_do_autoconfig(info);
			break;

		case TIOCSERGETLSR: /* Get line status register */
			ret = uart_get_lsr_info(info, (unsigned int *)arg);
			break;

		/*
		 * Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
		 * - mask passed in arg for lines of interest
		 *   (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
		 * Caller should use TIOCGICOUNT to see which one it was
		 */
		case TIOCMIWAIT:
			spin_lock_irq(&info->lock);
			/* note the counters on entry */
			cprev = info->port->icount;
			/* Force modem status interrupts on */
			info->ops->enable_ms(info->port);
			spin_unlock_irq(&info->lock);
			while (1) {
				interruptible_sleep_on(&info->delta_msr_wait);
				/* see if a signal did it */
				if (signal_pending(current)) {
					ret = -ERESTARTSYS;
					break;
				}
				spin_lock_irq(&info->lock);
				cnow = info->port->icount; /* atomic copy */
				spin_unlock_irq(&info->lock);
				if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
				    cnow.dcd == cprev.dcd && cnow.cts == cprev.cts) {
				    	ret = -EIO; /* no change => error */
				    	break;
				}
				if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
				    ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
				    ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
				    ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts))) {
				    	ret = 0;
				    	break;
				}
				cprev = cnow;
			}
			break;

		/*
		 * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
		 * Return: write counters to the user passed counter struct
		 * NB: both 1->0 and 0->1 transitions are counted except for
		 *     RI where only 0->1 is counted.
		 */
		case TIOCGICOUNT:
			spin_lock_irq(&info->lock);
			cnow = info->port->icount;
			spin_unlock_irq(&info->lock);

			icount.cts         = cnow.cts;
			icount.dsr         = cnow.dsr;
			icount.rng         = cnow.rng;
			icount.dcd         = cnow.dcd;
			icount.rx          = cnow.rx;
			icount.tx          = cnow.tx;
			icount.frame       = cnow.frame;
			icount.overrun     = cnow.overrun;
			icount.parity      = cnow.parity;
			icount.brk         = cnow.brk;
			icount.buf_overrun = cnow.buf_overrun;

			ret = copy_to_user((void *)arg, &icount, sizeof(icount))
					? -EFAULT : 0;
			break;

		case TIOCSERGWILD: /* obsolete */
		case TIOCSERSWILD: /* obsolete */
			ret = 0;
			break;

		default:
			if (info->ops->ioctl)
				ret = info->ops->ioctl(info->port, cmd, arg);
			break;
	}
	return ret;
}

static void uart_set_termios(struct tty_struct *tty, struct termios *old_termios)
{
	struct uart_info *info = tty->driver_data;
	unsigned long flags;
	unsigned int cflag = tty->termios->c_cflag;

	if ((cflag ^ old_termios->c_cflag) == 0 &&
	    RELEVENT_IFLAG(tty->termios->c_iflag ^ old_termios->c_iflag) == 0)
		return;

	uart_change_speed(info, old_termios);

	spin_lock_irqsave(&info->lock, flags);

	/* Handle transition to B0 status */
	if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD)) {
		info->mctrl &= ~(TIOCM_RTS | TIOCM_DTR);
		info->ops->set_mctrl(info->port, info->mctrl);
	}

	/* Handle transition away from B0 status */
	if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
		info->mctrl |= TIOCM_DTR;
		if (!(cflag & CRTSCTS) ||
		    !test_bit(TTY_THROTTLED, &tty->flags))
			info->mctrl |= TIOCM_RTS;
		info->ops->set_mctrl(info->port, info->mctrl);
	}

	/* Handle turning off CRTSCTS */
	if ((old_termios->c_cflag & CRTSCTS) && !(cflag & CRTSCTS)) {
		tty->hw_stopped = 0;
		__uart_start(tty);
	}
	spin_unlock_irqrestore(&info->lock, flags);

#if 0
	/*
	 * No need to wake up processes in open wait, since they
	 * sample the CLOCAL flag once, and don't recheck it.
	 * XXX  It's not clear whether the current behavior is correct
	 * or not.  Hence, this may change.....
	 */
	if (!(old_termios->c_cflag & CLOCAL) &&
	    (tty->termios->c_cflag & CLOCAL))
		wake_up_interruptible(&info->open_wait);
#endif
}

/*
 * In 2.4.5, calls to this will be serialized via the BKL in
 *  linux/drivers/char/tty_io.c:tty_release()
 *  linux/drivers/char/tty_io.c:do_tty_handup()
 */
static void uart_close(struct tty_struct *tty, struct file *filp)
{
	struct uart_driver *drv = (struct uart_driver *)tty->driver.driver_state;
	struct uart_info *info = tty->driver_data;
	struct uart_state *state;
	unsigned long flags;

	if (!info)
		return;

	state = info->state;

#ifdef DEBUG
	printk("uart_close() called\n");
#endif

	/*
	 * This is safe, as long as the BKL exists in
	 * do_tty_hangup(), and we're protected by the BKL.
	 */
	if (tty_hung_up_p(filp))
		goto done;

	down(&state->count_sem);
	spin_lock_irqsave(&info->lock, flags);
	if ((tty->count == 1) && (state->count != 1)) {
		/*
		 * Uh, oh.  tty->count is 1, which means that the tty
		 * structure will be freed.  state->count should always
		 * be one in these conditions.  If it's greater than
		 * one, we've got real problems, since it means the
		 * serial port won't be shutdown.
		 */
		printk("uart_close: bad serial port count; tty->count is 1, "
		       "state->count is %d\n", state->count);
		state->count = 1;
	}
	if (--state->count < 0) {
		printk("rs_close: bad serial port count for %s%d: %d\n",
		       tty->driver.name, info->port->line, state->count);
		state->count = 0;
	}
	if (state->count) {
		spin_unlock_irqrestore(&info->lock, flags);
		up(&state->count_sem);
		goto done;
	}
	info->flags |= ASYNC_CLOSING;
	spin_unlock_irqrestore(&info->lock, flags);
	up(&state->count_sem);

	/*
	 * Save the termios structure, since this port may have
	 * separate termios for callout and dialin.
	 */
	if (info->flags & ASYNC_NORMAL_ACTIVE)
		info->state->normal_termios = *tty->termios;
	if (info->flags & ASYNC_CALLOUT_ACTIVE)
		info->state->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 (info->state->closing_wait != ASYNC_CLOSING_WAIT_NONE)
		tty_wait_until_sent(tty, info->state->closing_wait);
	/*
	 * At this point, we stop accepting input.  To do this, we
	 * disable the receive line status interrupts.
	 */
	if (info->flags & ASYNC_INITIALIZED) {
		info->ops->stop_rx(info->port);
		/*
		 * Before we drop DTR, make sure the UART transmitter
		 * has completely drained; this is especially
		 * important if there is a transmit FIFO!
		 */
		uart_wait_until_sent(tty, info->timeout);
	}
	uart_shutdown(info);
	if (tty->driver.flush_buffer)
		tty->driver.flush_buffer(tty);
	if (tty->ldisc.flush_buffer)
		tty->ldisc.flush_buffer(tty);
	tty->closing = 0;
	info->event = 0;
	info->tty = NULL;
	if (info->blocked_open) {
		if (info->state->close_delay) {
			set_current_state(TASK_INTERRUPTIBLE);
			schedule_timeout(info->state->close_delay);
			set_current_state(TASK_RUNNING);