serial 8250: enable PPS support

Automagically function serial8250_enable_ms() is called when PPS ldisc
is selected.

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg KH <greg@kroah.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 16 insertions, 0 deletions

diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 7c4ebe6ee18b..c3db16b7afa1 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -2408,6 +2408,21 @@ serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
 }
 
 static void
+serial8250_set_ldisc(struct uart_port *port)
+{
+        int line = port->line;
+
+        if (line >= port->state->port.tty->driver->num)
+                return;
+
+        if (port->state->port.tty->ldisc->ops->num == N_PPS) {
+                port->flags |= UPF_HARDPPS_CD;
+                serial8250_enable_ms(port);
+        } else
+                port->flags &= ~UPF_HARDPPS_CD;
+}
+
+static void
 serial8250_pm(struct uart_port *port, unsigned int state,
               unsigned int oldstate)
 {
@@ -2628,6 +2643,7 @@ static struct uart_ops serial8250_pops = {
         .startup        = serial8250_startup,
         .shutdown       = serial8250_shutdown,
         .set_termios    = serial8250_set_termios,
+        .set_ldisc      = serial8250_set_ldisc,
         .pm             = serial8250_pm,
         .type           = serial8250_type,
         .release_port   = serial8250_release_port,