From 344cee2470ff70801c95c62ab2762da0834c8c6c Mon Sep 17 00:00:00 2001
From: "Matwey V. Kornilov" <matwey@sai.msu.ru>
Date: Mon, 1 Feb 2016 21:09:22 +0300
Subject: [PATCH] tty: 8250_omap: Use software emulated RS485 direction control
Git-commit: 344cee2470ff70801c95c62ab2762da0834c8c6c
Patch-mainline: 4.6-rc1
References: bsc#983152

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 <matwey@sai.msu.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/tty/serial/8250/8250_omap.c |   31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -697,6 +697,36 @@ static void omap_8250_throttle(struct ua
 	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);
+
+	/* Clamp the delays to [0, 100ms] */
+	rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U);
+	rs485->delay_rts_after_send  = min(rs485->delay_rts_after_send, 100U);
+
+	port->rs485 = *rs485;
+
+	/*
+	 * Both serial8250_em485_init and serial8250_em485_destroy
+	 * are idempotent
+	 */
+	if (rs485->flags & SER_RS485_ENABLED) {
+		int ret = serial8250_em485_init(up);
+
+		if (ret) {
+			rs485->flags &= ~SER_RS485_ENABLED;
+			port->rs485.flags &= ~SER_RS485_ENABLED;
+		}
+		return ret;
+	}
+
+	serial8250_em485_destroy(up);
+
+	return 0;
+}
+
 static void omap_8250_unthrottle(struct uart_port *port)
 {
 	unsigned long flags;
@@ -1146,6 +1176,7 @@ static int omap8250_probe(struct platfor
 	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;
