SERIAL: core: add hardware assisted s/w flow control support

[karo-tx-linux.git] / drivers / tty / serial / serial_core.c

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index bc2065d323b9798dcb9e313bca517ebd53702c96..bd10bbd564467eaa5fc2743d77d3b67111c469c6 100644 (file)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1213,7 +1213,19 @@ static void uart_set_termios(struct tty_struct *tty,
        struct uart_port *uport = state->uart_port;
        unsigned long flags;
        unsigned int cflag = tty->termios.c_cflag;
+       unsigned int iflag_mask = IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK;
+       bool sw_changed = false;
 
+       /*
+        * Drivers doing software flow control also need to know
+        * about changes to these input settings.
+        */
+       if (uport->flags & UPF_SOFT_FLOW) {
+               iflag_mask |= IXANY|IXON|IXOFF;
+               sw_changed =
+                  tty->termios.c_cc[VSTART] != old_termios->c_cc[VSTART] ||
+                  tty->termios.c_cc[VSTOP] != old_termios->c_cc[VSTOP];
+       }
 
        /*
         * These are the bits that are used to setup various
@@ -1221,11 +1233,11 @@ static void uart_set_termios(struct tty_struct *tty,
         * bits in c_cflag; c_[io]speed will always be set
         * appropriately by set_termios() in tty_ioctl.c
         */
-#define RELEVANT_IFLAG(iflag)  ((iflag) & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
        if ((cflag ^ old_termios->c_cflag) == 0 &&
            tty->termios.c_ospeed == old_termios->c_ospeed &&
            tty->termios.c_ispeed == old_termios->c_ispeed &&
-           RELEVANT_IFLAG(tty->termios.c_iflag ^ old_termios->c_iflag) == 0) {
+           ((tty->termios.c_iflag ^ old_termios->c_iflag) & iflag_mask) == 0 &&
+           !sw_changed) {
                return;
        }