tty: Add carrier processing on close to the tty_port core

Some drivers implement this internally, others miss it out. Push the
behaviour into the core code as that way everyone will do it consistently.

Update the dtr rts method to raise or lower depending upon flags. Having a
single method in this style fits most of the implementations more cleanly than
two funtions.

We need this in place before we tackle the USB side

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 23 insertions, 4 deletions

diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index 9b8004c72686..926d4a5593fa 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -137,7 +137,7 @@ int tty_port_carrier_raised(struct tty_port *port)
 EXPORT_SYMBOL(tty_port_carrier_raised);
 
 /**
- *      tty_port_raise_dtr_rts  -       Riase DTR/RTS
+ *      tty_port_raise_dtr_rts  -       Raise DTR/RTS
  *      @port: tty port
  *
  *      Wrapper for the DTR/RTS raise logic. For the moment this is used
@@ -147,12 +147,28 @@ EXPORT_SYMBOL(tty_port_carrier_raised);
 
 void tty_port_raise_dtr_rts(struct tty_port *port)
 {
-        if (port->ops->raise_dtr_rts)
-                port->ops->raise_dtr_rts(port);
+        if (port->ops->dtr_rts)
+                port->ops->dtr_rts(port, 1);
 }
 EXPORT_SYMBOL(tty_port_raise_dtr_rts);
 
 /**
+ *      tty_port_lower_dtr_rts  -       Lower DTR/RTS
+ *      @port: tty port
+ *
+ *      Wrapper for the DTR/RTS raise logic. For the moment this is used
+ *      to hide some internal details. This will eventually become entirely
+ *      internal to the tty port.
+ */
+
+void tty_port_lower_dtr_rts(struct tty_port *port)
+{
+        if (port->ops->dtr_rts)
+                port->ops->dtr_rts(port, 0);
+}
+EXPORT_SYMBOL(tty_port_lower_dtr_rts);
+
+/**
  *      tty_port_block_til_ready        -       Waiting logic for tty open
  *      @port: the tty port being opened
  *      @tty: the tty device being bound
@@ -167,7 +183,7 @@ EXPORT_SYMBOL(tty_port_raise_dtr_rts);
  *              - port flags and counts
  *
  *      The passed tty_port must implement the carrier_raised method if it can
- *      do carrier detect and the raise_dtr_rts method if it supports software
+ *      do carrier detect and the dtr_rts method if it supports software
  *      management of these lines. Note that the dtr/rts raise is done each
  *      iteration as a hangup may have previously dropped them while we wait.
  */
@@ -302,6 +318,9 @@ void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
 
         tty_ldisc_flush(tty);
 
+        if (tty->termios->c_cflag & HUPCL)
+                tty_port_lower_dtr_rts(port);
+
         spin_lock_irqsave(&port->lock, flags);
         tty->closing = 0;