[PATCH V3 3/3] USB: serial: f81232: implement break control

[Ji-Ze Hong (Peter Hong)]

Implement Fintek F81232 break on/off with LCR register.
It's the same with 16550A LCR register layout.

Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_ker...@gmail.com>
---
 drivers/usb/serial/f81232.c | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/serial/f81232.c b/drivers/usb/serial/f81232.c
index e7862997b6e4..9377b827313a 100644
--- a/drivers/usb/serial/f81232.c
+++ b/drivers/usb/serial/f81232.c
@@ -65,6 +65,7 @@ struct f81232_private {
        struct mutex lock;
        u8 modem_control;
        u8 modem_status;
+       u8 shadow_lcr;
        speed_t baud_base;
        struct work_struct lsr_work;
        struct work_struct interrupt_work;
@@ -377,13 +378,23 @@ static void f81232_process_read_urb(struct urb *urb)
 
 static void f81232_break_ctl(struct tty_struct *tty, int break_state)
 {
-       /* FIXME - Stubbed out for now */
+       struct usb_serial_port *port = tty->driver_data;
+       struct f81232_private *priv = usb_get_serial_port_data(port);
+       int status;
 
-       /*
-        * break_state = -1 to turn on break, and 0 to turn off break
-        * see drivers/char/tty_io.c to see it used.
-        * last_set_data_urb_value NEVER has the break bit set in it.
-        */
+       mutex_lock(&priv->lock);
+
+       if (break_state)
+               priv->shadow_lcr |= UART_LCR_SBC;
+       else
+               priv->shadow_lcr &= ~UART_LCR_SBC;
+
+       status = f81232_set_register(port, LINE_CONTROL_REGISTER,
+                                       priv->shadow_lcr);
+       if (status)
+               dev_err(&port->dev, "set break failed: %d\n", status);
+
+       mutex_unlock(&priv->lock);
 }
 
 static int f81232_find_clk(speed_t baudrate)
@@ -519,6 +530,7 @@ static int f81232_port_disable(struct usb_serial_port *port)
 static void f81232_set_termios(struct tty_struct *tty,
                struct usb_serial_port *port, struct ktermios *old_termios)
 {
+       struct f81232_private *priv = usb_get_serial_port_data(port);
        u8 new_lcr = 0;
        int status = 0;
        speed_t baudrate;
@@ -572,11 +584,16 @@ static void f81232_set_termios(struct tty_struct *tty,
                break;
        }
 
+       mutex_lock(&priv->lock);
+
+       new_lcr |= (priv->shadow_lcr & UART_LCR_SBC);
        status = f81232_set_register(port, LINE_CONTROL_REGISTER, new_lcr);
        if (status) {
                dev_err(&port->dev, "%s failed to set LCR: %d\n",
                        __func__, status);
        }
+
+       mutex_unlock(&priv->lock);
 }
 
 static int f81232_tiocmget(struct tty_struct *tty)
-- 
2.7.4