[PATCH V1 2/2] usb: serial: f81534: Implement break control

[Ji-Ze Hong (Peter Hong)]

Implement Fintek f81534 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/f81534.c | 46 +++++++++++++++++++++++++++++++++++++++------
 1 file changed, 40 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/serial/f81534.c b/drivers/usb/serial/f81534.c
index 3f47afa..9ea407d 100644
--- a/drivers/usb/serial/f81534.c
+++ b/drivers/usb/serial/f81534.c
@@ -128,11 +128,13 @@ struct f81534_serial_private {
 
 struct f81534_port_private {
        struct mutex mcr_mutex;
+       struct mutex lcr_mutex;
        struct work_struct lsr_work;
        struct usb_serial_port *port;
        unsigned long tx_empty;
        spinlock_t msr_lock;
        u8 shadow_mcr;
+       u8 shadow_lcr;
        u8 shadow_msr;
        u8 phy_num;
 };
@@ -465,6 +467,7 @@ static u32 f81534_calc_baud_divisor(u32 baudrate, u32 
clockrate)
 static int f81534_set_port_config(struct usb_serial_port *port, u32 baudrate,
                                        u8 lcr)
 {
+       struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
        u32 divisor;
        int status;
        u8 value;
@@ -493,35 +496,64 @@ static int f81534_set_port_config(struct usb_serial_port 
*port, u32 baudrate,
        }
 
        divisor = f81534_calc_baud_divisor(baudrate, F81534_MAX_BAUDRATE);
+
+       mutex_lock(&port_priv->lcr_mutex);
+
        value = UART_LCR_DLAB;
        status = f81534_set_port_register(port, F81534_LINE_CONTROL_REG,
                                                value);
        if (status) {
                dev_err(&port->dev, "%s: set LCR failed\n", __func__);
-               return status;
+               goto final;
        }
 
        value = divisor & 0xff;
        status = f81534_set_port_register(port, F81534_DIVISOR_LSB_REG, value);
        if (status) {
                dev_err(&port->dev, "%s: set DLAB LSB failed\n", __func__);
-               return status;
+               goto final;
        }
 
        value = (divisor >> 8) & 0xff;
        status = f81534_set_port_register(port, F81534_DIVISOR_MSB_REG, value);
        if (status) {
                dev_err(&port->dev, "%s: set DLAB MSB failed\n", __func__);
-               return status;
+               goto final;
        }
 
-       status = f81534_set_port_register(port, F81534_LINE_CONTROL_REG, lcr);
+       value = lcr | (port_priv->shadow_lcr & UART_LCR_SBC);
+       status = f81534_set_port_register(port, F81534_LINE_CONTROL_REG,
+                                               value);
        if (status) {
                dev_err(&port->dev, "%s: set LCR failed\n", __func__);
-               return status;
+               goto final;
        }
 
-       return 0;
+       port_priv->shadow_lcr = value;
+final:
+       mutex_unlock(&port_priv->lcr_mutex);
+       return status;
+}
+
+static void f81534_break_ctl(struct tty_struct *tty, int break_state)
+{
+       struct usb_serial_port *port = tty->driver_data;
+       struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
+       int status;
+
+       mutex_lock(&port_priv->lcr_mutex);
+
+       if (break_state)
+               port_priv->shadow_lcr |= UART_LCR_SBC;
+       else
+               port_priv->shadow_lcr &= ~UART_LCR_SBC;
+
+       status = f81534_set_port_register(port, F81534_LINE_CONTROL_REG,
+                                       port_priv->shadow_lcr);
+       if (status)
+               dev_err(&port->dev, "set break failed: %x\n", status);
+
+       mutex_unlock(&port_priv->lcr_mutex);
 }
 
 static int f81534_update_mctrl(struct usb_serial_port *port, unsigned int set,
@@ -1193,6 +1225,7 @@ static int f81534_port_probe(struct usb_serial_port *port)
 
        spin_lock_init(&port_priv->msr_lock);
        mutex_init(&port_priv->mcr_mutex);
+       mutex_init(&port_priv->lcr_mutex);
        INIT_WORK(&port_priv->lsr_work, f81534_lsr_worker);
 
        /* Assign logic-to-phy mapping */
@@ -1359,6 +1392,7 @@ static struct usb_serial_driver f81534_device = {
        .attach =               f81534_attach,
        .port_probe =           f81534_port_probe,
        .port_remove =          f81534_port_remove,
+       .break_ctl =            f81534_break_ctl,
        .dtr_rts =              f81534_dtr_rts,
        .process_read_urb =     f81534_process_read_urb,
        .ioctl =                f81534_ioctl,
-- 
2.7.4

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