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Commit 17b8f2a3 authored by Uwe Kleine-König's avatar Uwe Kleine-König Committed by Greg Kroah-Hartman
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serial: imx: add support for half duplex rs485 



The transmitter is expected to be controlled by the UART's RTS pin.

Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent afe9cbb1

drivers/tty/serial/imx.c

+95 −12
Original line number Diff line number Diff line
@@ -365,8 +365,23 @@ static void imx_stop_tx(struct uart_port *port) 
	if (sport->dma_is_enabled && sport->dma_is_txing)

		return;



	temp = readl(sport->port.membase + UCR1);

	writel(temp & ~UCR1_TXMPTYEN, sport->port.membase + UCR1);

	temp = readl(port->membase + UCR1);

	writel(temp & ~UCR1_TXMPTYEN, port->membase + UCR1);



	/* in rs485 mode disable transmitter if shifter is empty */

	if (port->rs485.flags & SER_RS485_ENABLED &&

	    readl(port->membase + USR2) & USR2_TXDC) {

		temp = readl(port->membase + UCR2);

		if (port->rs485.flags & SER_RS485_RTS_AFTER_SEND)

			temp &= ~UCR2_CTS;

		else

			temp |= UCR2_CTS;

		writel(temp, port->membase + UCR2);



		temp = readl(port->membase + UCR4);

		temp &= ~UCR4_TCEN;

		writel(temp, port->membase + UCR4);

	}

}



/*
@@ -560,6 +575,20 @@ static void imx_start_tx(struct uart_port *port) 
	struct imx_port *sport = (struct imx_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;

		else

			temp |= UCR2_CTS;

		writel(temp, port->membase + UCR2);



		temp = readl(port->membase + UCR4);

		temp |= UCR4_TCEN;

		writel(temp, port->membase + UCR4);

	}



	if (!sport->dma_is_enabled) {

		temp = readl(sport->port.membase + UCR1);

		writel(temp | UCR1_TXMPTYEN, sport->port.membase + UCR1);
@@ -715,6 +744,7 @@ static irqreturn_t imx_int(int irq, void *dev_id) 
	unsigned int sts2;



	sts = readl(sport->port.membase + USR1);

	sts2 = readl(sport->port.membase + USR2);



	if (sts & USR1_RRDY) {

		if (sport->dma_is_enabled)
@@ -723,8 +753,10 @@ static irqreturn_t imx_int(int irq, void *dev_id) 
			imx_rxint(irq, dev_id);

	}



	if (sts & USR1_TRDY &&

			readl(sport->port.membase + UCR1) & UCR1_TXMPTYEN)

	if ((sts & USR1_TRDY &&

	     readl(sport->port.membase + UCR1) & UCR1_TXMPTYEN) ||

	    (sts2 & USR2_TXDC &&

	     readl(sport->port.membase + UCR4) & UCR4_TCEN))

		imx_txint(irq, dev_id);



	if (sts & USR1_RTSD)
@@ -733,7 +765,6 @@ static irqreturn_t imx_int(int irq, void *dev_id) 
	if (sts & USR1_AWAKE)

		writel(USR1_AWAKE, sport->port.membase + USR1);



	sts2 = readl(sport->port.membase + USR2);

	if (sts2 & USR2_ORE) {

		dev_err(sport->port.dev, "Rx FIFO overrun\n");

		sport->port.icount.overrun++;
@@ -785,11 +816,13 @@ static void imx_set_mctrl(struct uart_port *port, unsigned int mctrl) 
	struct imx_port *sport = (struct imx_port *)port;

	unsigned long temp;



	temp = readl(sport->port.membase + UCR2) & ~(UCR2_CTS | UCR2_CTSC);

	if (!(port->rs485.flags & SER_RS485_ENABLED)) {

		temp = readl(sport->port.membase + UCR2);

		temp &= ~(UCR2_CTS | UCR2_CTSC);

		if (mctrl & TIOCM_RTS)

			temp |= UCR2_CTS | UCR2_CTSC;



		writel(temp, sport->port.membase + UCR2);

	}



	temp = readl(sport->port.membase + uts_reg(sport)) & ~UTS_LOOP;

	if (mctrl & TIOCM_LOOP)
@@ -1264,11 +1297,26 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios, 
	if (termios->c_cflag & CRTSCTS) {

		if (sport->have_rtscts) {

			ucr2 &= ~UCR2_IRTS;



			if (port->rs485.flags & SER_RS485_ENABLED)

				/*

				 * RTS is mandatory for rs485 operation, so keep

				 * it under manual control and keep transmitter

				 * disabled.

				 */

				if (!(port->rs485.flags &

				      SER_RS485_RTS_AFTER_SEND))

					ucr2 |= UCR2_CTS;

			else

				ucr2 |= UCR2_CTSC;



		} else {

			termios->c_cflag &= ~CRTSCTS;

		}

	}

	} else if (port->rs485.flags & SER_RS485_ENABLED)

		/* disable transmitter */

		if (!(port->rs485.flags & SER_RS485_RTS_AFTER_SEND))

			ucr2 |= UCR2_CTS;



	if (termios->c_cflag & CSTOPB)

		ucr2 |= UCR2_STPB;
@@ -1490,6 +1538,38 @@ static void imx_poll_put_char(struct uart_port *port, unsigned char c) 
}

#endif



static int imx_rs485_config(struct uart_port *port,

			    struct serial_rs485 *rs485conf)

{

	struct imx_port *sport = (struct imx_port *)port;



	/* unimplemented */

	rs485conf->delay_rts_before_send = 0;

	rs485conf->delay_rts_after_send = 0;

	rs485conf->flags |= SER_RS485_RX_DURING_TX;



	/* RTS is required to control the transmitter */

	if (!sport->have_rtscts)

		rs485conf->flags &= ~SER_RS485_ENABLED;



	if (rs485conf->flags & SER_RS485_ENABLED) {

		unsigned long temp;



		/* disable transmitter */

		temp = readl(sport->port.membase + UCR2);

		temp &= ~UCR2_CTSC;

		if (rs485conf->flags & SER_RS485_RTS_AFTER_SEND)

			temp &= ~UCR2_CTS;

		else

			temp |= UCR2_CTS;

		writel(temp, sport->port.membase + UCR2);

	}



	port->rs485 = *rs485conf;



	return 0;

}



static struct uart_ops imx_pops = {

	.tx_empty	= imx_tx_empty,

	.set_mctrl	= imx_set_mctrl,
@@ -1847,6 +1927,9 @@ static int serial_imx_probe(struct platform_device *pdev) 
	sport->port.irq = rxirq;

	sport->port.fifosize = 32;

	sport->port.ops = &imx_pops;

	sport->port.rs485_config = imx_rs485_config;

	sport->port.rs485.flags =

		SER_RS485_RTS_ON_SEND | SER_RS485_RX_DURING_TX;

	sport->port.flags = UPF_BOOT_AUTOCONF;

	init_timer(&sport->timer);

	sport->timer.function = imx_timeout;