[PATCH V4 3/3] USB: serial: f81232: implement break control

Ji-Ze Hong (Peter Hong)
2019-04-02T05:26:54Z

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_kernel@gmail.com>
---
v4:
1: no change

v3:
1: using shadow_lcr to save LCR in f81232_break_ctl()

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 37da345acafd..763a51222384 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;
bool lsr_work_resched;
struct work_struct lsr_work;
@@ -378,13 +379,23 @@ 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)
@@ -520,6 +531,7 @@ 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;
@@ -573,11 +585,16 @@ 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