[PATCH v2 2/3] serial: 8250: introduce get_divisor() and set_divisor() hook

From: Jisheng Zhang
Date: Wed Jul 04 2018 - 05:04:22 EST


Add these two hooks so that they can be overridden with driver specific
implementations.

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@xxxxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_core.c | 4 ++++
drivers/tty/serial/8250/8250_port.c | 27 +++++++++++++++++++++++----
include/linux/serial_core.h | 7 +++++++
3 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 9342fc2ee7df..a0bb77290747 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1023,6 +1023,10 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
uart->port.get_mctrl = up->port.get_mctrl;
if (up->port.set_mctrl)
uart->port.set_mctrl = up->port.set_mctrl;
+ if (up->port.get_divisor)
+ uart->port.get_divisor = up->port.get_divisor;
+ if (up->port.set_divisor)
+ uart->port.set_divisor = up->port.set_divisor;
if (up->port.startup)
uart->port.startup = up->port.startup;
if (up->port.shutdown)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 709fe6b4265c..ce0dc17f18ee 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2498,9 +2498,9 @@ static unsigned int npcm_get_divisor(struct uart_8250_port *up,
return DIV_ROUND_CLOSEST(port->uartclk, 16 * baud + 2) - 2;
}

-static unsigned int serial8250_get_divisor(struct uart_port *port,
- unsigned int baud,
- unsigned int *frac)
+static unsigned int serial8250_do_get_divisor(struct uart_port *port,
+ unsigned int baud,
+ unsigned int *frac)
{
struct uart_8250_port *up = up_to_u8250p(port);
unsigned int quot;
@@ -2532,6 +2532,16 @@ static unsigned int serial8250_get_divisor(struct uart_port *port,
return quot;
}

+static unsigned int serial8250_get_divisor(struct uart_port *port,
+ unsigned int baud,
+ unsigned int *frac)
+{
+ if (port->get_divisor)
+ return port->get_divisor(port, baud, frac);
+
+ return serial8250_do_get_divisor(port, baud, frac);
+}
+
static unsigned char serial8250_compute_lcr(struct uart_8250_port *up,
tcflag_t c_cflag)
{
@@ -2570,7 +2580,7 @@ static unsigned char serial8250_compute_lcr(struct uart_8250_port *up,
return cval;
}

-static void serial8250_set_divisor(struct uart_port *port, unsigned int baud,
+static void serial8250_do_set_divisor(struct uart_port *port, unsigned int baud,
unsigned int quot, unsigned int quot_frac)
{
struct uart_8250_port *up = up_to_u8250p(port);
@@ -2603,6 +2613,15 @@ static void serial8250_set_divisor(struct uart_port *port, unsigned int baud,
}
}

+static void serial8250_set_divisor(struct uart_port *port, unsigned int baud,
+ unsigned int quot, unsigned int quot_frac)
+{
+ if (port->set_divisor)
+ port->set_divisor(port, baud, quot, quot_frac);
+ else
+ serial8250_do_set_divisor(port, baud, quot, quot_frac);
+}
+
static unsigned int serial8250_get_baud_rate(struct uart_port *port,
struct ktermios *termios,
struct ktermios *old)
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 06ea4eeb09ab..406edae44ca3 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -127,6 +127,13 @@ struct uart_port {
struct ktermios *);
unsigned int (*get_mctrl)(struct uart_port *);
void (*set_mctrl)(struct uart_port *, unsigned int);
+ unsigned int (*get_divisor)(struct uart_port *,
+ unsigned int baud,
+ unsigned int *frac);
+ void (*set_divisor)(struct uart_port *,
+ unsigned int baud,
+ unsigned int quot,
+ unsigned int quot_frac);
int (*startup)(struct uart_port *port);
void (*shutdown)(struct uart_port *port);
void (*throttle)(struct uart_port *port);
--
2.18.0