From 17b8f2a3fdca29a9b296642fb3f6ad3c39ffc7d3 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Uwe=20Kleine-K=C3=B6nig?= Date: Tue, 24 Feb 2015 11:17:11 +0100 Subject: [PATCH] serial: imx: add support for half duplex rs485 MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The transmitter is expected to be controlled by the UART's RTS pin. Signed-off-by: Uwe Kleine-König Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/imx.c | 107 ++++++++++++++++++++++++++++++++++----- 1 file changed, 95 insertions(+), 12 deletions(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 6dc1d2781b86..ddfb672d0152 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -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 (mctrl & TIOCM_RTS) - temp |= UCR2_CTS | UCR2_CTSC; - - writel(temp, sport->port.membase + UCR2); + 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; - ucr2 |= UCR2_CTSC; + + 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; -- 2.20.1