linux-kernel - [PATCH 5/9] serial: omap-serial: add support for rs485 RTS delays in microseconds

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Date:   Wed, 20 Feb 2019 16:27:27 +0100
From:   Martin Kepplinger <martin.kepplinger@...zinger.com>
To:     <gregkh@...uxfoundation.org>, <robh+dt@...nel.org>,
        <mark.rutland@....com>, <jslaby@...e.com>, <corbet@....net>,
        <richard.genoud@...il.com>, <nicolas.ferre@...rochip.com>,
        <alexandre.belloni@...tlin.com>, <ludovic.desroches@...rochip.com>,
        <mcoquelin.stm32@...il.com>, <alexandre.torgue@...com>,
        <linux-serial@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-stm32@...md-mailman.stormreply.com>
CC:     <linux-kernel@...r.kernel.org>
Subject: [PATCH 5/9] serial: omap-serial: add support for rs485 RTS delays in microseconds

Read struct serial_rs485's flag SER_RS485_DELAY_IN_USEC and apply the delay
accordingly.

Signed-off-by: Martin Kepplinger <martin.kepplinger@...zinger.com>
---
 drivers/tty/serial/omap-serial.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 6420ae581a80..adcd75ce5112 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -310,7 +310,11 @@ static void serial_omap_stop_tx(struct uart_port *port)
 			res = (port->rs485.flags & SER_RS485_RTS_AFTER_SEND) ?
 				1 : 0;
 			if (gpio_get_value(up->rts_gpio) != res) {
-				if (port->rs485.delay_rts_after_send > 0)
+				if (port->rs485.delay_rts_after_send > 0 &&
+				    port->rs485.flags & SER_RS485_DELAY_IN_USEC)
+					udelay(
+					port->rs485.delay_rts_after_send);
+				else if (port->rs485.delay_rts_after_send > 0)
 					mdelay(
 					port->rs485.delay_rts_after_send);
 				gpio_set_value(up->rts_gpio, res);
@@ -420,7 +424,11 @@ static void serial_omap_start_tx(struct uart_port *port)
 		res = (port->rs485.flags & SER_RS485_RTS_ON_SEND) ? 1 : 0;
 		if (gpio_get_value(up->rts_gpio) != res) {
 			gpio_set_value(up->rts_gpio, res);
-			if (port->rs485.delay_rts_before_send > 0)
+			if (port->rs485.delay_rts_before_send > 0 &&
+			    port->rs485.flags & SER_RS485_DELAY_IN_USEC)
+				udelay(port->rs485.delay_rts_before_send);
+			else if (port->rs485.delay_rts_before_send > 0 &&
+				 !(port->rs485.flags & SER_RS485_DELAY_IN_USEC)
 				mdelay(port->rs485.delay_rts_before_send);
 		}
 	}
@@ -1407,8 +1415,17 @@ serial_omap_config_rs485(struct uart_port *port, struct serial_rs485 *rs485)
 	serial_out(up, UART_IER, 0);
 
 	/* 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);
+	if (port->rs485.flags & SER_RS485_DELAY_IN_USEC) {
+		rs485->delay_rts_before_send = min(rs485->delay_rts_before_send,
+						   100000U);
+		rs485->delay_rts_after_send  = min(rs485->delay_rts_after_send,
+						   100000U);
+	} else {
+		rs485->delay_rts_before_send = min(rs485->delay_rts_before_send,
+						   100);
+		rs485->delay_rts_after_send  = min(rs485->delay_rts_after_send,
+						   100U);
+	}
 
 	/* store new config */
 	port->rs485 = *rs485;
-- 
2.20.1


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