serial_core.c

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static void uart_unthrottle(struct tty_struct *tty)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port = state->port;

	if (I_IXOFF(tty)) {
		if (port->x_char)
			port->x_char = 0;
		else
			uart_send_xchar(tty, START_CHAR(tty));
	}

	if (tty->termios->c_cflag & CRTSCTS)
		uart_set_mctrl(port, TIOCM_RTS);
}

static int uart_get_info(struct uart_state *state,
			 struct serial_struct __user *retinfo)
{
	struct uart_port *port = state->port;
	struct serial_struct tmp;

	memset(&tmp, 0, sizeof(tmp));
	tmp.type	    = port->type;
	tmp.line	    = port->line;
	tmp.port	    = port->iobase;
	if (HIGH_BITS_OFFSET)
		tmp.port_high = (long) port->iobase >> HIGH_BITS_OFFSET;
	tmp.irq		    = port->irq;
	tmp.flags	    = port->flags;
	tmp.xmit_fifo_size  = port->fifosize;
	tmp.baud_base	    = port->uartclk / 16;
	tmp.close_delay	    = state->close_delay / 10;
	tmp.closing_wait    = state->closing_wait == USF_CLOSING_WAIT_NONE ?
				ASYNC_CLOSING_WAIT_NONE :
			        state->closing_wait / 10;
	tmp.custom_divisor  = port->custom_divisor;
	tmp.hub6	    = port->hub6;
	tmp.io_type         = port->iotype;
	tmp.iomem_reg_shift = port->regshift;
	tmp.iomem_base      = (void *)port->mapbase;

	if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
		return -EFAULT;
	return 0;
}

static int uart_set_info(struct uart_state *state,
			 struct serial_struct __user *newinfo)
{
	struct serial_struct new_serial;
	struct uart_port *port = state->port;
	unsigned long new_port;
	unsigned int change_irq, change_port, closing_wait;
	unsigned int old_custom_divisor, close_delay;
	upf_t old_flags, new_flags;
	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_canonicalize(new_serial.irq);
	close_delay = new_serial.close_delay * 10;
	closing_wait = new_serial.closing_wait == ASYNC_CLOSING_WAIT_NONE ?
			USF_CLOSING_WAIT_NONE : new_serial.closing_wait * 10;

	/*
	 * 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.
	 */
	mutex_lock(&state->mutex);

	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;
	new_flags = new_serial.flags;
	old_custom_divisor = port->custom_divisor;

	if (!capable(CAP_SYS_ADMIN)) {
		retval = -EPERM;
		if (change_irq || change_port ||
		    (new_serial.baud_base != port->uartclk / 16) ||
		    (close_delay != state->close_delay) ||
		    (closing_wait != state->closing_wait) ||
		    (new_serial.xmit_fifo_size != port->fifosize) ||
		    (((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
			goto exit;
		port->flags = ((port->flags & ~UPF_USR_MASK) |
			       (new_flags & UPF_USR_MASK));
		port->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 (uart_users(state) > 1)
			goto exit;

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

	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);
		} else {
			/* Always success - Jean II */
			retval = 0;
		}

		/*
		 * 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 & ~UPF_CHANGE_MASK) |
				 (new_flags & UPF_CHANGE_MASK);
	port->custom_divisor   = new_serial.custom_divisor;
	state->close_delay     = close_delay;
	state->closing_wait    = closing_wait;
	port->fifosize         = new_serial.xmit_fifo_size;
	if (state->info->tty)
		state->info->tty->low_latency =
			(port->flags & UPF_LOW_LATENCY) ? 1 : 0;

 check_and_exit:
	retval = 0;
	if (port->type == PORT_UNKNOWN)
		goto exit;
	if (state->info->flags & UIF_INITIALIZED) {
		if (((old_flags ^ port->flags) & UPF_SPD_MASK) ||
		    old_custom_divisor != port->custom_divisor) {
			/*
			 * If they're setting up a custom divisor or speed,
			 * instead of clearing it, then bitch about it. No
			 * need to rate-limit; it's CAP_SYS_ADMIN only.
			 */
			if (port->flags & UPF_SPD_MASK) {
				char buf[64];
				printk(KERN_NOTICE
				       "%s sets custom speed on %s. This "
				       "is deprecated.\n", current->comm,
				       tty_name(state->info->tty, buf));
			}
			uart_change_speed(state, NULL);
		}
	} else
		retval = uart_startup(state, 1);
 exit:
	mutex_unlock(&state->mutex);
	return retval;
}


/*
 * uart_get_lsr_info - get line status register info.
 * Note: uart_ioctl protects us against hangups.
 */
static int uart_get_lsr_info(struct uart_state *state,
			     unsigned int __user *value)
{
	struct uart_port *port = state->port;
	unsigned int result;

	result = port->ops->tx_empty(port);

	/*
	 * 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 (port->x_char ||
	    ((uart_circ_chars_pending(&state->info->xmit) > 0) &&
	     !state->info->tty->stopped && !state->info->tty->hw_stopped))
		result &= ~TIOCSER_TEMT;
	
	return put_user(result, value);
}

static int uart_tiocmget(struct tty_struct *tty, struct file *file)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port = state->port;
	int result = -EIO;

	mutex_lock(&state->mutex);
	if ((!file || !tty_hung_up_p(file)) &&
	    !(tty->flags & (1 << TTY_IO_ERROR))) {
		result = port->mctrl;

		spin_lock_irq(&port->lock);
		result |= port->ops->get_mctrl(port);
		spin_unlock_irq(&port->lock);
	}
	mutex_unlock(&state->mutex);

	return result;
}

static int
uart_tiocmset(struct tty_struct *tty, struct file *file,
	      unsigned int set, unsigned int clear)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port = state->port;
	int ret = -EIO;

	mutex_lock(&state->mutex);
	if ((!file || !tty_hung_up_p(file)) &&
	    !(tty->flags & (1 << TTY_IO_ERROR))) {
		uart_update_mctrl(port, set, clear);
		ret = 0;
	}
	mutex_unlock(&state->mutex);
	return ret;
}

static void uart_break_ctl(struct tty_struct *tty, int break_state)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port = state->port;

	BUG_ON(!kernel_locked());

	mutex_lock(&state->mutex);

	if (port->type != PORT_UNKNOWN)
		port->ops->break_ctl(port, break_state);

	mutex_unlock(&state->mutex);
}

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

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

	/*
	 * Take the per-port semaphore.  This prevents count from
	 * changing, and hence any extra opens of the port while
	 * we're auto-configuring.
	 */
	if (mutex_lock_interruptible(&state->mutex))
		return -ERESTARTSYS;

	ret = -EBUSY;
	if (uart_users(state) == 1) {
		uart_shutdown(state);

		/*
		 * 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 & UPF_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(state, 1);
	}
	mutex_unlock(&state->mutex);
	return ret;
}

/*
 * 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
 */
static int
uart_wait_modem_status(struct uart_state *state, unsigned long arg)
{
	struct uart_port *port = state->port;
	DECLARE_WAITQUEUE(wait, current);
	struct uart_icount cprev, cnow;
	int ret;

	/*
	 * note the counters on entry
	 */
	spin_lock_irq(&port->lock);
	memcpy(&cprev, &port->icount, sizeof(struct uart_icount));

	/*
	 * Force modem status interrupts on
	 */
	port->ops->enable_ms(port);
	spin_unlock_irq(&port->lock);

	add_wait_queue(&state->info->delta_msr_wait, &wait);
	for (;;) {
		spin_lock_irq(&port->lock);
		memcpy(&cnow, &port->icount, sizeof(struct uart_icount));
		spin_unlock_irq(&port->lock);

		set_current_state(TASK_INTERRUPTIBLE);

		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;
		}

		schedule();

		/* see if a signal did it */
		if (signal_pending(current)) {
			ret = -ERESTARTSYS;
			break;
		}

		cprev = cnow;
	}

	current->state = TASK_RUNNING;
	remove_wait_queue(&state->info->delta_msr_wait, &wait);

	return ret;
}

/*
 * 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.
 */
static int uart_get_count(struct uart_state *state,
			  struct serial_icounter_struct __user *icnt)
{
	struct serial_icounter_struct icount;
	struct uart_icount cnow;
	struct uart_port *port = state->port;

	spin_lock_irq(&port->lock);
	memcpy(&cnow, &port->icount, sizeof(struct uart_icount));
	spin_unlock_irq(&port->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;

	return copy_to_user(icnt, &icount, sizeof(icount)) ? -EFAULT : 0;
}

/*
 * Called via sys_ioctl under the BKL.  We can use spin_lock_irq() here.
 */
static int
uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd,
	   unsigned long arg)
{
	struct uart_state *state = tty->driver_data;
	void __user *uarg = (void __user *)arg;
	int ret = -ENOIOCTLCMD;

	BUG_ON(!kernel_locked());

	/*
	 * These ioctls don't rely on the hardware to be present.
	 */
	switch (cmd) {
	case TIOCGSERIAL:
		ret = uart_get_info(state, uarg);
		break;

	case TIOCSSERIAL:
		ret = uart_set_info(state, uarg);
		break;

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

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

	if (ret != -ENOIOCTLCMD)
		goto out;

	if (tty->flags & (1 << TTY_IO_ERROR)) {
		ret = -EIO;
		goto out;
	}

	/*
	 * The following should only be used when hardware is present.
	 */
	switch (cmd) {
	case TIOCMIWAIT:
		ret = uart_wait_modem_status(state, arg);
		break;

	case TIOCGICOUNT:
		ret = uart_get_count(state, uarg);
		break;
	}

	if (ret != -ENOIOCTLCMD)
		goto out;

	mutex_lock(&state->mutex);

	if (tty_hung_up_p(filp)) {
		ret = -EIO;
		goto out_up;
	}

	/*
	 * All these rely on hardware being present and need to be
	 * protected against the tty being hung up.
	 */
	switch (cmd) {
	case TIOCSERGETLSR: /* Get line status register */
		ret = uart_get_lsr_info(state, uarg);
		break;

	default: {
		struct uart_port *port = state->port;
		if (port->ops->ioctl)
			ret = port->ops->ioctl(port, cmd, arg);
		break;
	}
	}
 out_up:
	mutex_unlock(&state->mutex);
 out:
	return ret;
}

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

	BUG_ON(!kernel_locked());

	/*
	 * These are the bits that are used to setup various
	 * flags in the low level driver.
	 */
#define RELEVANT_IFLAG(iflag)	((iflag) & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))

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

	uart_change_speed(state, old_termios);

	/* Handle transition to B0 status */
	if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD))
		uart_clear_mctrl(state->port, TIOCM_RTS | TIOCM_DTR);

	/* Handle transition away from B0 status */
	if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
		unsigned int mask = TIOCM_DTR;
		if (!(cflag & CRTSCTS) ||
		    !test_bit(TTY_THROTTLED, &tty->flags))
			mask |= TIOCM_RTS;
		uart_set_mctrl(state->port, mask);
	}

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

	/* Handle turning on CRTSCTS */
	if (!(old_termios->c_cflag & CRTSCTS) && (cflag & CRTSCTS)) {
		spin_lock_irqsave(&state->port->lock, flags);
		if (!(state->port->ops->get_mctrl(state->port) & TIOCM_CTS)) {