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authorFabio Estevam <fabio.estevam@nxp.com>2017-01-30 09:12:11 -0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-01-31 10:54:58 +0100
commit1a613626d2895f4f6b95a3b0a6413e52e00b5f95 (patch)
tree3e99a29f2287675072b10bbb187d7883fde6dd16 /drivers/tty
parentaa42db44f6705334c6130103492484ea3c7199b3 (diff)
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.c20
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);
}