pps: serial clients support

Adds support, by using the PPS line discipline, for the PPS sources
connected with the CD (Carrier Detect) pin of a serial port.

[akpm@linux-foundation.org: fix cast size warnings]
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, 10 insertions, 1 deletions

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 8c3dd36fe91a..78dd1e7120a9 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -491,9 +491,13 @@ uart_handle_dcd_change(struct uart_port *uport, unsigned int status)
 {
         struct uart_state *state = uport->state;
         struct tty_port *port = &state->port;
+        struct tty_ldisc *ld = tty_ldisc_ref(port->tty);
+        struct timespec ts;
 
-        uport->icount.dcd++;
+        if (ld && ld->ops->dcd_change)
+                getnstimeofday(&ts);
 
+        uport->icount.dcd++;
 #ifdef CONFIG_HARD_PPS
         if ((uport->flags & UPF_HARDPPS_CD) && status)
                 hardpps();
@@ -505,6 +509,11 @@ uart_handle_dcd_change(struct uart_port *uport, unsigned int status)
                 else if (port->tty)
                         tty_hangup(port->tty);
         }
+
+        if (ld && ld->ops->dcd_change)
+                ld->ops->dcd_change(port->tty, status, &ts);
+        if (ld)
+                tty_ldisc_deref(ld);
 }
 
 /**