Moxa PCIe serial boards requires custom break signal transmission under
RS485 mdoe. However, the current 8250 driver does not provide a way for
low-level driver to override this behavior.
This patch introduces a break_ctl() function pointer in struct
uart_port, allowing low-level drivers to customize the break signal
transmission logic. If no custom implementation is provided, the default
serial8250_do_break_ctl() function is used. This ensures that
hardware-specific break signaling can be implemented without affecting
standard behavior.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
---
drivers/tty/serial/8250/8250_core.c | 2 ++
drivers/tty/serial/8250/8250_port.c | 11 ++++++++++-
include/linux/serial_8250.h | 1 +
include/linux/serial_core.h | 1 +
4 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 68baf75bdadc..f642e8c77911 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -802,6 +802,8 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
uart->port.startup = up->port.startup;
if (up->port.shutdown)
uart->port.shutdown = up->port.shutdown;
+ if (up->port.break_ctl)
+ uart->port.break_ctl = up->port.break_ctl;
if (up->port.pm)
uart->port.pm = up->port.pm;
if (up->port.handle_break)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 38825bb80749..64896f37b75d 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2079,7 +2079,7 @@ static void serial8250_set_mctrl(struct uart_port *port, unsigned int mctrl)
serial8250_do_set_mctrl(port, mctrl);
}
-static void serial8250_break_ctl(struct uart_port *port, int break_state)
+void serial8250_do_break_ctl(struct uart_port *port, int break_state)
{
struct uart_8250_port *up = up_to_u8250p(port);
unsigned long flags;
@@ -2094,6 +2094,15 @@ static void serial8250_break_ctl(struct uart_port *port, int break_state)
uart_port_unlock_irqrestore(port, flags);
serial8250_rpm_put(up);
}
+EXPORT_SYMBOL_GPL(serial8250_do_break_ctl);
+
+static void serial8250_break_ctl(struct uart_port *port, int break_state)
+{
+ if (port->break_ctl)
+ port->break_ctl(port, break_state);
+ else
+ serial8250_do_break_ctl(port, break_state);
+}
static void wait_for_lsr(struct uart_8250_port *up, int bits)
{
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index e0717c8393d7..88996a3194de 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -192,6 +192,7 @@ void serial8250_do_shutdown(struct uart_port *port);
void serial8250_do_pm(struct uart_port *port, unsigned int state,
unsigned int oldstate);
void serial8250_do_set_mctrl(struct uart_port *port, unsigned int mctrl);
+void serial8250_do_break_ctl(struct uart_port *port, int break_state);
void serial8250_do_set_divisor(struct uart_port *port, unsigned int baud,
unsigned int quot);
int fsl8250_handle_irq(struct uart_port *port);
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 743b4afaad4c..1aa07c5187d8 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -451,6 +451,7 @@ struct uart_port {
void (*shutdown)(struct uart_port *port);
void (*throttle)(struct uart_port *port);
void (*unthrottle)(struct uart_port *port);
+ void (*break_ctl)(struct uart_port *port, int break_state);
int (*handle_irq)(struct uart_port *);
void (*pm)(struct uart_port *, unsigned int state,
unsigned int old);
--
2.45.2