Until this point, it has not been possible for serial applications
to toggle the UART RTS line. This can be useful with certain
configurations. For example, when using a Mezzanine on a Linaro
96board, RTS line is used to take the the on-board microcontroller
in and out of reset.
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
---
drivers/tty/serial/st-asc.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
index 379e5bd..ce46898 100644
--- a/drivers/tty/serial/st-asc.c
+++ b/drivers/tty/serial/st-asc.c
@@ -30,6 +30,7 @@
#include <linux/of_platform.h>
#include <linux/serial_core.h>
#include <linux/clk.h>
+#include <linux/gpio/consumer.h>
#define DRIVER_NAME "st-asc"
#define ASC_SERIAL_NAME "ttyAS"
@@ -38,6 +39,7 @@
struct asc_port {
struct uart_port port;
+ struct gpio_desc *rts;
struct clk *clk;
unsigned int hw_flow_control:1;
unsigned int force_m1:1;
@@ -381,12 +383,16 @@ static unsigned int asc_tx_empty(struct uart_port *port)
static void asc_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
+ struct asc_port *ascport = to_asc_port(port);
+
/*
* This routine is used for seting signals of: DTR, DCD, CTS/RTS
* We use ASC's hardware for CTS/RTS, so don't need any for that.
* Some boards have DTR and DCD implemented using PIO pins,
* code to do this should be hooked in here.
*/
+
+ gpiod_set_value(ascport->rts, mctrl & TIOCM_RTS);
}
static unsigned int asc_get_mctrl(struct uart_port *port)
@@ -731,12 +737,20 @@ MODULE_DEVICE_TABLE(of, asc_match);
static int asc_serial_probe(struct platform_device *pdev)
{
int ret;
+ struct device_node *np = pdev->dev.of_node;
struct asc_port *ascport;
+ struct gpio_desc *gpiod;
ascport = asc_of_get_asc_port(pdev);
if (!ascport)
return -ENODEV;
+ gpiod = devm_get_gpiod_from_child(&pdev->dev, "rts", &np->fwnode);
+ if (!IS_ERR(gpiod)) {
+ gpiod_direction_output(gpiod, 0);
+ ascport->rts = gpiod;
+ }
+
ret = asc_init_port(ascport, pdev);
if (ret)
return ret;
--
2.10.2
--
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