tty: rework break handling

Some hardware needs to do break handling itself and may have partial
support only. Make break_ctl return an error code. Add a tty driver flag
so you can indicate driver hardware side break support.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 8 insertions, 4 deletions

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 95ae6377d7e5..0725b1871f23 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -732,13 +732,16 @@ static void acm_tty_unthrottle(struct tty_struct *tty)
         tasklet_schedule(&acm->urb_task);
 }
 
-static void acm_tty_break_ctl(struct tty_struct *tty, int state)
+static int acm_tty_break_ctl(struct tty_struct *tty, int state)
 {
         struct acm *acm = tty->driver_data;
+        int retval;
         if (!ACM_READY(acm))
-                return;
-        if (acm_send_break(acm, state ? 0xffff : 0))
+                return -EINVAL;
+        retval = acm_send_break(acm, state ? 0xffff : 0);
+        if (retval < 0)
                 dbg("send break failed");
+        return retval;
 }
 
 static int acm_tty_tiocmget(struct tty_struct *tty, struct file *file)
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 51917b0f079a..8c2d531eedea 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -395,7 +395,7 @@ static void serial_set_termios(struct tty_struct *tty, struct ktermios *old)
                 tty_termios_copy_hw(tty->termios, old);
 }
 
-static void serial_break(struct tty_struct *tty, int break_state)
+static int serial_break(struct tty_struct *tty, int break_state)
 {
         struct usb_serial_port *port = tty->driver_data;
 
@@ -409,6 +409,7 @@ static void serial_break(struct tty_struct *tty, int break_state)
                 port->serial->type->break_ctl(tty, break_state);
                 unlock_kernel();
         }
+        return 0;
 }
 
 static int serial_read_proc(char *page, char **start, off_t off, int count,