diff options
| author |   Baruch Siach <baruch@tkos.co.il> | 2016-02-29 14:34:10 +0200 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-04-30 09:26:55 -0700 |
| commit | 7d1cadca957d3c586fe71054ed843565013236d9 (patch) | |
| tree | 617a186a73de93d8d81fa2c808584e1642288114 /drivers/tty/serial/imx.c | |
| parent | serial: Make SERIAL_MVEBU_UART depend on ARCH_MVEBU (diff) | |
| download | linux-dev-7d1cadca957d3c586fe71054ed843565013236d9.tar.xz linux-dev-7d1cadca957d3c586fe71054ed843565013236d9.zip | |
serial: imx: support RS-485 Rx disable on Tx
Some RS-232 to RS-485 transceivers require Rx to be disabled on Tx to
avoid echo of Tx data into the Rx buffer. Specifically, the XR3160E
RS-232/RS-485/RS-422 transceiver behaves this way.
This commit disables Rx on active Tx when SER_RS485_ENABLED is active and
SER_RS485_RX_DURING_TX is disabled.
Note that this is a change in behavior of the driver. Until now
SER_RS485_RX_DURING_TX was enabled unconditionally even when disabled in
the TIOCSRS485 ioctl serial_rs485 flags field.
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/imx.c')
| -rw-r--r-- | drivers/tty/serial/imx.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 231e7d5caf6c..66cc3d198dcf 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -361,6 +361,7 @@ static void imx_stop_tx(struct uart_port *port) imx_port_rts_inactive(sport, &temp); else imx_port_rts_active(sport, &temp); + temp |= UCR2_RXEN; writel(temp, port->membase + UCR2); temp = readl(port->membase + UCR4); @@ -568,6 +569,8 @@ static void imx_start_tx(struct uart_port *port) imx_port_rts_inactive(sport, &temp); else imx_port_rts_active(sport, &temp); + if (!(port->rs485.flags & SER_RS485_RX_DURING_TX)) + temp &= ~UCR2_RXEN; writel(temp, port->membase + UCR2); /* enable transmitter and shifter empty irq */ @@ -1610,19 +1613,17 @@ static int imx_rs485_config(struct uart_port *port, struct serial_rs485 *rs485conf) { struct imx_port *sport = (struct imx_port *)port; + unsigned long temp; /* 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); if (rs485conf->flags & SER_RS485_RTS_AFTER_SEND) @@ -1632,6 +1633,14 @@ static int imx_rs485_config(struct uart_port *port, writel(temp, sport->port.membase + UCR2); } + /* Make sure Rx is enabled in case Tx is active with Rx disabled */ + if (!(rs485conf->flags & SER_RS485_ENABLED) || + rs485conf->flags & SER_RS485_RX_DURING_TX) { + temp = readl(sport->port.membase + UCR2); + temp |= UCR2_RXEN; + writel(temp, sport->port.membase + UCR2); + } + port->rs485 = *rs485conf; return 0; |