For Synopsys DesignWare 8250 uart which version >= 4.00a, there's a
valid divisor latch fraction register. The fractional divisor width is
4bits ~ 6bits. Add get_divisor() and set_divisor() hook to prepare
supporting this feature in next commit.
Signed-off-by: Jisheng Zhang <Jisheng.Zhang@xxxxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_core.c | 4 ++++
drivers/tty/serial/8250/8250_port.c | 8 ++++++++
include/linux/serial_8250.h | 7 +++++++
3 files changed, 19 insertions(+)
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 9342fc2ee7df..da0f3849bfce 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1035,6 +1035,10 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
uart->dl_read = up->dl_read;
if (up->dl_write)
uart->dl_write = up->dl_write;
+ if (up->get_divisor)
+ uart->get_divisor = up->get_divisor;
+ if (up->set_divisor)
+ uart->set_divisor = up->set_divisor;
if (uart->port.type != PORT_8250_CIR) {
if (serial8250_isa_config != NULL)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index cf541aab2bd0..0060ec54a522 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2505,6 +2505,9 @@ static unsigned int serial8250_get_divisor(struct uart_8250_port *up,
struct uart_port *port = &up->port;
unsigned int quot;
+ if (up->get_divisor)
+ return up->get_divisor(up, baud, frac);
+
/*
* Handle magic divisors for baud rates above baud_base on
* SMSC SuperIO chips.
@@ -2575,6 +2578,11 @@ static void serial8250_set_divisor(struct uart_port *port, unsigned int baud,
{
struct uart_8250_port *up = up_to_u8250p(port);
+ if (up->set_divisor) {
+ up->set_divisor(up, baud, quot, quot_frac);
+ return;
+ }
+
/* Workaround to enable 115200 baud on OMAP1510 internal ports */
if (is_omap1510_8250(up)) {
if (baud == 115200) {
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 76b9db71e489..5093c9ca0980 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -132,6 +132,13 @@ struct uart_8250_port {
/* 8250 specific callbacks */
int (*dl_read)(struct uart_8250_port *);
void (*dl_write)(struct uart_8250_port *, int);
+ unsigned int (*get_divisor)(struct uart_8250_port *up,
+ unsigned int baud,
+ unsigned int *frac);
+ void (*set_divisor)(struct uart_8250_port *up,
+ unsigned int baud,
+ unsigned int quot,
+ unsigned int quot_frac);
struct uart_8250_em485 *em485;
};
--
2.18.0
--
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