Add RTS watermark support for LPUART. The RX RTS_B output negates when
the number of empty words in the receive FIFO is greater or equal to
RTSWATER. Here set the RTSWATER to half of the rxfifo_size.
Signed-off-by: Sherry Sun <sherry.sun@xxxxxxx>
---
drivers/tty/serial/fsl_lpuart.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 2789749d3d0d..c35e49a09bcc 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -201,6 +201,7 @@
#define UARTDATA_MASK 0x3ff
#define UARTMODIR_IREN 0x00020000
+#define UARTMODIR_RTSWATER GENMASK(10, 8)
#define UARTMODIR_TXCTSSRC 0x00000020
#define UARTMODIR_TXCTSC 0x00000010
#define UARTMODIR_RXRTSE 0x00000008
@@ -1573,6 +1574,13 @@ static void lpuart32_setup_watermark(struct lpuart_port *sport)
(0x0 << UARTWATER_TXWATER_OFF);
lpuart32_write(&sport->port, val, UARTWATER);
+ /* set RTS watermark */
+ if (!uart_console(&sport->port)) {
+ val = lpuart32_read(&sport->port, UARTMODIR);
+ val |= FIELD_PREP(UARTMODIR_RTSWATER, sport->rxfifo_size >> 1);
+ lpuart32_write(&sport->port, val, UARTMODIR);
+ }
+
/* Restore cr2 */
lpuart32_write(&sport->port, ctrl_saved, UARTCTRL);
}
--
2.17.1
