sc16is7xx: expose RTS inversion in RS-485 mode
Hardware is capable of inverting RTS signal when working
in RS-485 mode. Expose this functionality to user space.
Relay on a matching combination of standard flags
(SER_RS485_RTS_ON_SEND and SER_RS485_RTS_AFTER_SEND) to
detect when user space is requesting inverted RTS mode.
Signed-off-by: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Jon Ringle <jringle@gridpoint.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 36b3c26..468354e 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -829,16 +829,32 @@
}
static int sc16is7xx_config_rs485(struct uart_port *port,
- struct serial_rs485 *rs485)
+ struct serial_rs485 *rs485)
{
- if (port->rs485.flags & SER_RS485_ENABLED)
- sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG,
- SC16IS7XX_EFCR_AUTO_RS485_BIT,
- SC16IS7XX_EFCR_AUTO_RS485_BIT);
- else
- sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG,
- SC16IS7XX_EFCR_AUTO_RS485_BIT,
- 0);
+ const u32 mask = SC16IS7XX_EFCR_AUTO_RS485_BIT |
+ SC16IS7XX_EFCR_RTS_INVERT_BIT;
+ u32 efcr = 0;
+
+ if (rs485->flags & SER_RS485_ENABLED) {
+ bool rts_during_rx, rts_during_tx;
+
+ rts_during_rx = rs485->flags & SER_RS485_RTS_AFTER_SEND;
+ rts_during_tx = rs485->flags & SER_RS485_RTS_ON_SEND;
+
+ efcr |= SC16IS7XX_EFCR_AUTO_RS485_BIT;
+
+ if (!rts_during_rx && rts_during_tx)
+ /* default */;
+ else if (rts_during_rx && !rts_during_tx)
+ efcr |= SC16IS7XX_EFCR_RTS_INVERT_BIT;
+ else
+ dev_err(port->dev,
+ "unsupported RTS signalling on_send:%d after_send:%d - exactly one of RS485 RTS flags should be set\n",
+ rts_during_tx, rts_during_rx);
+ }
+
+ sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG, mask, efcr);
+
port->rs485 = *rs485;
return 0;