Use software emulated RS485 direction control to provide RS485 API existed in
omap_serial driver. Note that 8250_omap issues interrupt on shift register
empty which is single prerequesite for using software emulated RS485.

Signed-off-by: Matwey V. Kornilov <mat...@sai.msu.ru>
---
 drivers/tty/serial/8250/8250_omap.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_omap.c 
b/drivers/tty/serial/8250/8250_omap.c
index 826c5c4..323c0a4 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -698,6 +698,23 @@ static void omap_8250_throttle(struct uart_port *port)
        pm_runtime_put_autosuspend(port->dev);
 }
 
+static int omap_8250_rs485_config(struct uart_port *port, struct serial_rs485 
*rs485)
+{
+       struct uart_8250_port *up = up_to_u8250p(port);
+
+       if (rs485->flags & SER_RS485_ENABLED && !serial8250_em485_enabled(up)) {
+               port->rs485 = *rs485;
+               return serial8250_em485_init(up);
+       }
+
+       if (serial8250_em485_enabled(up) && !(rs485->flags & SER_RS485_ENABLED))
+               serial8250_em485_destroy(up);
+
+       port->rs485 = *rs485;
+
+       return 0;
+}
+
 static void omap_8250_unthrottle(struct uart_port *port)
 {
        unsigned long flags;
@@ -1144,6 +1161,7 @@ static int omap8250_probe(struct platform_device *pdev)
        up.port.shutdown = omap_8250_shutdown;
        up.port.throttle = omap_8250_throttle;
        up.port.unthrottle = omap_8250_unthrottle;
+       up.port.rs485_config = omap_8250_rs485_config;
 
        if (pdev->dev.of_node) {
                const struct of_device_id *id;
-- 
2.6.3

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