serial: imx: implement handshaking using gpios with the mctrl_gpio helpertopic/serial-handshaking

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

2 files changed, 70 insertions, 20 deletions

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index c0ed0c733c9d..dc40ffb61b25 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -574,6 +574,7 @@ config SERIAL_IMX
 	depends on ARCH_MXC || COMPILE_TEST
 	select SERIAL_CORE
 	select RATIONAL
+	select SERIAL_MCTRL_GPIO if GPIOLIB
 	help
 	  If you have a machine based on a Motorola IMX CPU you
 	  can enable its onboard serial port by enabling this option.
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 0a58fd07c840..c2a38eb38805 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -44,6 +44,8 @@
 #include <linux/platform_data/serial-imx.h>
 #include <linux/platform_data/dma-imx.h>
 
+#include "serial_mctrl_gpio.h"
+
 /* Register definitions */
 #define URXD0 0x0  /* Receiver Register */
 #define URTX0 0x40 /* Transmitter Register */
@@ -208,6 +210,8 @@ struct imx_port {
 	struct clk		*clk_per;
 	const struct imx_uart_data *devdata;
 
+	struct mctrl_gpios *gpios;
+
 	/* DMA fields */
 	unsigned int		dma_is_inited:1;
 	unsigned int		dma_is_enabled:1;
@@ -310,6 +314,26 @@ static void imx_port_ucrs_restore(struct uart_port *port,
 }
 #endif
 
+static void imx_port_rts_active(struct imx_port *sport, unsigned long *ucr2)
+{
+	*ucr2 &= ~UCR2_CTSC;
+	*ucr2 |= UCR2_CTS;
+
+	mctrl_gpio_set(sport->gpios, sport->port.mctrl | TIOCM_RTS);
+}
+
+static void imx_port_rts_inactive(struct imx_port *sport, unsigned long *ucr2)
+{
+	*ucr2 &= ~(UCR2_CTSC | UCR2_CTS);
+
+	mctrl_gpio_set(sport->gpios, sport->port.mctrl & ~TIOCM_RTS);
+}
+
+static void imx_port_rts_auto(struct imx_port *sport, unsigned long *ucr2)
+{
+	*ucr2 |= UCR2_CTSC;
+}
+
 /*
  * interrupts disabled on entry
  */
@@ -333,9 +357,9 @@ static void imx_stop_tx(struct uart_port *port)
 	    readl(port->membase + USR2) & USR2_TXDC) {
 		temp = readl(port->membase + UCR2);
 		if (port->rs485.flags & SER_RS485_RTS_AFTER_SEND)
-			temp &= ~UCR2_CTS;
+			imx_port_rts_inactive(sport, &temp);
 		else
-			temp |= UCR2_CTS;
+			imx_port_rts_active(sport, &temp);
 		writel(temp, port->membase + UCR2);
 
 		temp = readl(port->membase + UCR4);
@@ -377,6 +401,8 @@ static void imx_enable_ms(struct uart_port *port)
 	struct imx_port *sport = (struct imx_port *)port;
 
 	mod_timer(&sport->timer, jiffies);
+
+	mctrl_gpio_enable_ms(sport->gpios);
 }
 
 static void imx_dma_tx(struct imx_port *sport);
@@ -536,14 +562,14 @@ static void imx_start_tx(struct uart_port *port)
 	unsigned long temp;
 
 	if (port->rs485.flags & SER_RS485_ENABLED) {
-		/* enable transmitter and shifter empty irq */
 		temp = readl(port->membase + UCR2);
 		if (port->rs485.flags & SER_RS485_RTS_ON_SEND)
-			temp &= ~UCR2_CTS;
+			imx_port_rts_inactive(sport, &temp);
 		else
-			temp |= UCR2_CTS;
+			imx_port_rts_active(sport, &temp);
 		writel(temp, port->membase + UCR2);
 
+		/* enable transmitter and shifter empty irq */
 		temp = readl(port->membase + UCR4);
 		temp |= UCR4_TCEN;
 		writel(temp, port->membase + UCR4);
@@ -754,9 +780,8 @@ static unsigned int imx_tx_empty(struct uart_port *port)
 /*
  * We have a modem side uart, so the meanings of RTS and CTS are inverted.
  */
-static unsigned int imx_get_mctrl(struct uart_port *port)
+static unsigned int imx_get_hwmctrl(struct imx_port *sport)
 {
-	struct imx_port *sport = (struct imx_port *)port;
 	unsigned int tmp = TIOCM_DSR;
 	unsigned usr1 = readl(sport->port.membase + USR1);
 
@@ -774,6 +799,16 @@ static unsigned int imx_get_mctrl(struct uart_port *port)
 	return tmp;
 }
 
+static unsigned int imx_get_mctrl(struct uart_port *port)
+{
+	struct imx_port *sport = (struct imx_port *)port;
+	unsigned int ret = imx_get_hwmctrl(sport);
+
+	mctrl_gpio_get(sport->gpios, &ret);
+
+	return ret;
+}
+
 static void imx_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
 	struct imx_port *sport = (struct imx_port *)port;
@@ -796,6 +831,8 @@ static void imx_set_mctrl(struct uart_port *port, unsigned int mctrl)
 	if (mctrl & TIOCM_LOOP)
 		temp |= UTS_LOOP;
 	writel(temp, sport->port.membase + uts_reg(sport));
+
+	mctrl_gpio_set(sport->gpios, mctrl);
 }
 
 /*
@@ -828,7 +865,7 @@ static void imx_mctrl_check(struct imx_port *sport)
 {
 	unsigned int status, changed;
 
-	status = imx_get_mctrl(&sport->port);
+	status = imx_get_hwmctrl(sport);
 	changed = status ^ sport->old_status;
 
 	if (changed == 0)
@@ -1212,6 +1249,8 @@ static void imx_shutdown(struct uart_port *port)
 		imx_uart_dma_exit(sport);
 	}
 
+	mctrl_gpio_disable_ms(sport->gpios);
+
 	spin_lock_irqsave(&sport->port.lock, flags);
 	temp = readl(sport->port.membase + UCR2);
 	temp &= ~(UCR2_TXEN);
@@ -1289,9 +1328,10 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
 {
 	struct imx_port *sport = (struct imx_port *)port;
 	unsigned long flags;
-	unsigned int ucr2, old_ucr1, old_txrxen, baud, quot;
+	unsigned long ucr2, old_ucr1, old_txrxen;
+	unsigned int baud, quot;
 	unsigned int old_csize = old ? old->c_cflag & CSIZE : CS8;
-	unsigned int div, ufcr;
+	unsigned long div, ufcr;
 	unsigned long num, denom;
 	uint64_t tdiv64;
 
@@ -1320,11 +1360,13 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
 				 * it under manual control and keep transmitter
 				 * disabled.
 				 */
-				if (!(port->rs485.flags &
-				      SER_RS485_RTS_AFTER_SEND))
-					ucr2 |= UCR2_CTS;
+				if (port->rs485.flags &
+				    SER_RS485_RTS_AFTER_SEND)
+					imx_port_rts_inactive(sport, &ucr2);
+				else
+					imx_port_rts_active(sport, &ucr2);
 			} else {
-				ucr2 |= UCR2_CTSC;
+				imx_port_rts_auto(sport, &ucr2);
 			}
 
 			/* Can we enable the DMA support? */
@@ -1334,10 +1376,14 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
 		} else {
 			termios->c_cflag &= ~CRTSCTS;
 		}
-	} else if (port->rs485.flags & SER_RS485_ENABLED)
+	} else if (port->rs485.flags & SER_RS485_ENABLED) {
 		/* disable transmitter */
-		if (!(port->rs485.flags & SER_RS485_RTS_AFTER_SEND))
-			ucr2 |= UCR2_CTS;
+		if (port->rs485.flags & SER_RS485_RTS_AFTER_SEND)
+			imx_port_rts_inactive(sport, &ucr2);
+		else
+			imx_port_rts_active(sport, &ucr2);
+	}
+
 
 	if (termios->c_cflag & CSTOPB)
 		ucr2 |= UCR2_STPB;
@@ -1580,11 +1626,10 @@ static int imx_rs485_config(struct uart_port *port,
 
 		/* disable transmitter */
 		temp = readl(sport->port.membase + UCR2);
-		temp &= ~UCR2_CTSC;
 		if (rs485conf->flags & SER_RS485_RTS_AFTER_SEND)
-			temp &= ~UCR2_CTS;
+			imx_port_rts_inactive(sport, &temp);
 		else
-			temp |= UCR2_CTS;
+			imx_port_rts_active(sport, &temp);
 		writel(temp, sport->port.membase + UCR2);
 	}
 
@@ -1920,6 +1965,10 @@ static int serial_imx_probe(struct platform_device *pdev)
 	sport->timer.function = imx_timeout;
 	sport->timer.data     = (unsigned long)sport;
 
+	sport->gpios = mctrl_gpio_init(&sport->port, 0);
+	if (IS_ERR(sport->gpios))
+		return PTR_ERR(sport->gpios);
+
 	sport->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
 	if (IS_ERR(sport->clk_ipg)) {
 		ret = PTR_ERR(sport->clk_ipg);