[SERIAL] Move make modem control signals accessible to line discplines

We also parse modem control signals in the tty layer, and fail with
EINVAL if the driver does not provide the methods.  All tty drivers
which require modem control support should be updated to provide
the new tiocmset and tiocmget methods.

4 files changed, 103 insertions, 58 deletions

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index acacb8cfe527..d494768620a5 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1691,6 +1691,55 @@ static int send_break(struct tty_struct *tty, int duration)
 	return 0;
 }
 
+static int
+tty_tiocmget(struct tty_struct *tty, struct file *file, unsigned long arg)
+{
+	int retval = -EINVAL;
+
+	if (tty->driver.tiocmget) {
+		retval = tty->driver.tiocmget(tty, file);
+
+		if (retval >= 0)
+			retval = put_user(retval, (int *)arg);
+	}
+	return retval;
+}
+
+static int
+tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
+	     unsigned long arg)
+{
+	int retval = -EINVAL;
+
+	if (tty->driver.tiocmset) {
+		unsigned int set, clear, val;
+
+		retval = get_user(val, (unsigned int *)arg);
+		if (retval)
+			return retval;
+
+		set = clear = 0;
+		switch (cmd) {
+		case TIOCMBIS:
+			set = val;
+			break;
+		case TIOCMBIC:
+			clear = val;
+			break;
+		case TIOCMSET:
+			set = val;
+			clear = ~val;
+			break;
+		}
+
+		set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2;
+		clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2;
+
+		retval = tty->driver.tiocmset(tty, file, set, clear);
+	}
+	return retval;
+}
+
 /*
  * Split this up, as gcc can choke on it otherwise..
  */
@@ -1816,6 +1865,14 @@ int tty_ioctl(struct inode * inode, struct file * file,
 			return 0;
 		case TCSBRKP:	/* support for POSIX tcsendbreak() */	
 			return send_break(tty, arg ? arg*(HZ/10) : HZ/4);
+
+		case TIOCMGET:
+			return tty_tiocmget(tty, file, arg);
+
+		case TIOCMSET:
+		case TIOCMBIC:
+		case TIOCMBIS:
+			return tty_tiocmset(tty, file, cmd, arg);
 	}
 	if (tty->driver.ioctl) {
 		int retval = (tty->driver.ioctl)(tty, file, cmd, arg);
diff --git a/drivers/net/irda/irtty-sir.c b/drivers/net/irda/irtty-sir.c
index 3049b0f6e74f..90cb66d944c3 100644
--- a/drivers/net/irda/irtty-sir.c
+++ b/drivers/net/irda/irtty-sir.c
@@ -180,32 +180,29 @@ static int irtty_change_speed(struct sir_dev *dev, unsigned speed)
 static int irtty_set_dtr_rts(struct sir_dev *dev, int dtr, int rts)
 {
 	struct sirtty_cb *priv = dev->priv;
-	int arg = 0;
+	int set = 0;
+	int clear = 0;
 
 	ASSERT(priv != NULL, return -1;);
 	ASSERT(priv->magic == IRTTY_MAGIC, return -1;);
 
-#ifdef TIOCM_OUT2 /* Not defined for ARM */
-	arg = TIOCM_OUT2;
-#endif
 	if (rts)
-		arg |= TIOCM_RTS;
+		set |= TIOCM_RTS;
+	else
+		clear |= TIOCM_RTS;
 	if (dtr)
-		arg |= TIOCM_DTR;
+		set |= TIOCM_DTR;
+	else
+		clear |= TIOCM_DTR;
 
 	/*
-	 * The ioctl() function, or actually set_modem_info() in serial.c
-	 * expects a pointer to the argument in user space. This is working
-	 * here because we are always called from the kIrDAd thread which
-	 * has set_fs(KERNEL_DS) permanently set. Therefore copy_from_user()
-	 * is happy with our arg-parameter being local here in kernel space.
+	 * We can't use ioctl() because it expects a non-null file structure,
+	 * and we don't have that here.
+	 * This function is not yet defined for all tty driver, so
+	 * let's be careful... Jean II
 	 */
-
-	lock_kernel();
-	if (priv->tty->driver.ioctl(priv->tty, NULL, TIOCMSET, (unsigned long) &arg)) { 
-		IRDA_DEBUG(2, "%s(), error doing ioctl!\n", __FUNCTION__);
-	}
-	unlock_kernel();
+	ASSERT(priv->tty->driver.tiocmset != NULL, return -1;);
+	priv->tty->driver.tiocmset(priv->tty, NULL, set, clear);
 
 	return 0;
 }
diff --git a/drivers/serial/core.c b/drivers/serial/core.c
index cd71c9e65fb0..b461093a13cc 100644
--- a/drivers/serial/core.c
+++ b/drivers/serial/core.c
@@ -873,45 +873,38 @@ static int uart_get_lsr_info(struct uart_state *state, unsigned int *value)
 	return put_user(result, value);
 }
 
-static int uart_get_modem_info(struct uart_port *port, unsigned int *value)
+static int uart_tiocmget(struct tty_struct *tty, struct file *file)
 {
-	unsigned int result = port->mctrl;
+	struct uart_state *state = tty->driver_data;
+	struct uart_port *port = state->port;
+	int result = -EIO;
 
-	result |= port->ops->get_mctrl(port);
+	down(&state->sem);
+	if ((!file || !tty_hung_up_p(file)) &&
+	    !(tty->flags & (1 << TTY_IO_ERROR))) {
+		result = port->mctrl;
+		result |= port->ops->get_mctrl(port);
+	}
+	up(&state->sem);
 
-	return put_user(result, value);
+	return result;
 }
 
 static int
-uart_set_modem_info(struct uart_port *port, unsigned int cmd,
-		    unsigned int *value)
+uart_tiocmset(struct tty_struct *tty, struct file *file,
+	      unsigned int set, unsigned int clear)
 {
-	unsigned int arg, set, clear;
-	int ret = 0;
-
-	if (get_user(arg, value))
-		return -EFAULT;
-
-	arg &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2;
+	struct uart_state *state = tty->driver_data;
+	struct uart_port *port = state->port;
+	int ret = -EIO;
 
-	set = clear = 0;
-	switch (cmd) {
-	case TIOCMBIS:
-		set = arg;
-		break;
-	case TIOCMBIC:
-		clear = arg;
-		break;
-	case TIOCMSET:
-		set = arg;
-		clear = ~arg;
-		break;
-	default:
-		ret = -EINVAL;
-		break;
-	}
-	if (ret == 0)
+	down(&state->sem);
+	if ((!file || !tty_hung_up_p(file)) &&
+	    !(tty->flags & (1 << TTY_IO_ERROR))) {
 		uart_update_mctrl(port, set, clear);
+		ret = 0;
+	}
+	up(&state->sem);
 	return ret;
 }
 
@@ -922,8 +915,12 @@ static void uart_break_ctl(struct tty_struct *tty, int break_state)
 
 	BUG_ON(!kernel_locked());
 
+	down(&state->sem);
+
 	if (port->type != PORT_UNKNOWN)
 		port->ops->break_ctl(port, break_state);
+
+	up(&state->sem);
 }
 
 static int uart_do_autoconfig(struct uart_state *state)
@@ -1130,17 +1127,6 @@ uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd,
 	 * protected against the tty being hung up.
 	 */
 	switch (cmd) {
-	case TIOCMGET:
-		ret = uart_get_modem_info(state->port, (unsigned int *)arg);
-		break;
-
-	case TIOCMBIS:
-	case TIOCMBIC:
-	case TIOCMSET:
-		ret = uart_set_modem_info(state->port, cmd,
-					  (unsigned int *)arg);
-		break;
-
 	case TIOCSERGETLSR: /* Get line status register */
 		ret = uart_get_lsr_info(state, (unsigned int *)arg);
 		break;
@@ -2162,6 +2148,8 @@ int uart_register_driver(struct uart_driver *drv)
 #ifdef CONFIG_PROC_FS
 	normal->read_proc	= uart_read_proc;
 #endif
+	normal->tiocmget	= uart_tiocmget;
+	normal->tiocmset	= uart_tiocmset;
 
 	/*
 	 * Initialise the UART state(s).
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 0070ed49813d..0e35590dc50c 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -172,6 +172,9 @@ struct tty_driver {
 			  int count, int *eof, void *data);
 	int (*write_proc)(struct file *file, const char *buffer,
 			  unsigned long count, void *data);
+	int (*tiocmget)(struct tty_struct *tty, struct file *file);
+	int (*tiocmset)(struct tty_struct *tty, struct file *file,
+			unsigned int set, unsigned int clear);
 	struct list_head tty_drivers;
 };