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| author |   Fabio Estevam <fabio.estevam@nxp.com> | 2017-01-30 09:12:11 -0200 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-01-31 10:54:58 +0100 |
| commit | 1a613626d2895f4f6b95a3b0a6413e52e00b5f95 (patch) | |
| tree | 3e99a29f2287675072b10bbb187d7883fde6dd16 /drivers/tty | |
| parent | 8250: of: remove remnants of generic of_serial driver (diff) | |
| download | linux-dev-1a613626d2895f4f6b95a3b0a6413e52e00b5f95.tar.xz linux-dev-1a613626d2895f4f6b95a3b0a6413e52e00b5f95.zip | |
serial: imx: Fix the RTS GPIO polarity in RS485 mode
On a board that needs to drive RTS GPIO high in order to enable the
transmission of a RS485 transceiver the following description is
passed in the devide tree:
&uart4 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_uart4>;
rts-gpios = <&gpio6 2 GPIO_ACTIVE_HIGH>;
status = "okay";
};
and userspace configures the uart port as follows:
/* enable RS485 mode: */
rs485conf.flags |= SER_RS485_ENABLED;
/* set logical level for RTS pin equal to 1 when sending: */
rs485conf.flags |= SER_RS485_RTS_ON_SEND;
/* set logical level for RTS pin equal to 0 after sending: */
rs485conf.flags &= ~(SER_RS485_RTS_AFTER_SEND);
However the RTS GPIO polarity observed in the oscilloscope is inverted.
When the SER_RS485_RTS_ON_SEND flag is set the imx_port_rts_active()
function should be called and following the same logic when
SER_RS485_RTS_AFTER_SEND flag is cleared the imx_port_rts_inactive()
should be called.
Do such logic change so that RS485 communication in half duplex can
work successfully when the RTS GPIO pin is passed via device tree.
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/imx.c | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 33fcc84e756b..29dd57c51706 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -377,9 +377,9 @@ 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) - imx_port_rts_inactive(sport, &temp); - else imx_port_rts_active(sport, &temp); + else + imx_port_rts_inactive(sport, &temp); temp |= UCR2_RXEN; writel(temp, port->membase + UCR2); @@ -585,9 +585,9 @@ static void imx_start_tx(struct uart_port *port) if (port->rs485.flags & SER_RS485_ENABLED) { temp = readl(port->membase + UCR2); if (port->rs485.flags & SER_RS485_RTS_ON_SEND) - imx_port_rts_inactive(sport, &temp); - else imx_port_rts_active(sport, &temp); + else + imx_port_rts_inactive(sport, &temp); if (!(port->rs485.flags & SER_RS485_RX_DURING_TX)) temp &= ~UCR2_RXEN; writel(temp, port->membase + UCR2); @@ -1477,9 +1477,9 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios, */ if (port->rs485.flags & SER_RS485_RTS_AFTER_SEND) - imx_port_rts_inactive(sport, &ucr2); - else imx_port_rts_active(sport, &ucr2); + else + imx_port_rts_inactive(sport, &ucr2); } else { imx_port_rts_auto(sport, &ucr2); } @@ -1489,9 +1489,9 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios, } else if (port->rs485.flags & SER_RS485_ENABLED) { /* disable transmitter */ if (port->rs485.flags & SER_RS485_RTS_AFTER_SEND) - imx_port_rts_inactive(sport, &ucr2); - else imx_port_rts_active(sport, &ucr2); + else + imx_port_rts_inactive(sport, &ucr2); } @@ -1733,9 +1733,9 @@ static int imx_rs485_config(struct uart_port *port, /* disable transmitter */ temp = readl(sport->port.membase + UCR2); if (rs485conf->flags & SER_RS485_RTS_AFTER_SEND) - imx_port_rts_inactive(sport, &temp); - else imx_port_rts_active(sport, &temp); + else + imx_port_rts_inactive(sport, &temp); writel(temp, sport->port.membase + UCR2); } |