Add "SER_RS485_MODE_RS422" flag to struct serial_rs485, so that serial
port can switch interface into RS422 if supported by using ioctl command
"TIOCSRS485".
By treating RS422 as a mode of RS485, which means while enabling RS422
there are two flags need to be set (SER_RS485_ENABLED and
SER_RS485_MODE_RS422), it would make things much easier. For example
some places that checks for "SER_RS485_ENABLED" won't need to be rewritten.
Signed-off-by: Crescent CY Hsieh <crescentcy.hsieh@xxxxxxxx>
---
drivers/tty/serial/serial_core.c | 6 ++++++
include/uapi/linux/serial.h | 2 ++
2 files changed, 8 insertions(+)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 831d03361..a195ec1ab 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1376,6 +1376,12 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4
return;
}
+ /* Clear other RS485 flags but SER_RS485_TERMINATE_BUS and return if enabling RS422 */
+ if (rs485->flags & SER_RS485_MODE_RS422) {
+ rs485->flags &= (SER_RS485_ENABLED | SER_RS485_MODE_RS422 | SER_RS485_TERMINATE_BUS);
+ return;
+ }
+
/* Pick sane settings if the user hasn't */
if ((supported_flags & (SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND)) &&
!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
index 6c75ebdd7..9086367db 100644
--- a/include/uapi/linux/serial.h
+++ b/include/uapi/linux/serial.h
@@ -138,6 +138,7 @@ struct serial_icounter_struct {
* * %SER_RS485_ADDRB - Enable RS485 addressing mode.
* * %SER_RS485_ADDR_RECV - Receive address filter (enables @addr_recv). Requires %SER_RS485_ADDRB.
* * %SER_RS485_ADDR_DEST - Destination address (enables @addr_dest). Requires %SER_RS485_ADDRB.
+ * * %SER_RS485_MODE_RS422 - Enable RS422. Requires %SER_RS485_ENABLED.
*/
struct serial_rs485 {
__u32 flags;
@@ -149,6 +150,7 @@ struct serial_rs485 {
#define SER_RS485_ADDRB _BITUL(5)
#define SER_RS485_ADDR_RECV _BITUL(6)
#define SER_RS485_ADDR_DEST _BITUL(7)
+#define SER_RS485_MODE_RS422 _BITUL(8)
__u32 delay_rts_before_send;
__u32 delay_rts_after_send;
--
2.34.1
