[PATCH V3] tty: serial: Fix bit order in RS485 flag definitions

[Christoph Niedermaier]

Since the commit 93f3350c46fa ("RS485: fix inconsistencies in the
meaning of some variables"), the definition for bit 3 has been removed.
But with the switch to bit shift macros in commit 76ac8e29855b ("tty:
serial: Cleanup the bit shift with macro"), this gap wasn't preserved.
To avoid a break in user/kernel api of the system skip bit 3 again and
add a placeholder comment.

Signed-off-by: Christoph Niedermaier <cniedermaier at dh-electronics.com>
Fixes: 76ac8e29855b ("tty: serial: Cleanup the bit shift with macro")
Fixes: 6056f20f27e9 ("tty: serial: Add RS422 flag to struct serial_rs485")
Reviewed-by: Jiri Slaby <jirislaby at kernel.org>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Cc: Crescent CY Hsieh <crescentcy.hsieh at moxa.com>
Cc: Jiri Slaby <jirislaby at kernel.org>
Cc: Lukas Wunner <lukas at wunner.de>
Cc: Lino Sanfilippo <l.sanfilippo at kunbus.com>
Cc: Hugo Villeneuve <hugo at hugovil.com>
---
V2: - Fix typo
    - Add Fixes tags
V3: - Add Reviewed-by tag
    - Remove triple dash after the last Fixes tag
    - Remove all "To:"s after "Cc:"
---
 include/uapi/linux/serial.h | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
index 9086367db043..de9b4733607e 100644
--- a/include/uapi/linux/serial.h
+++ b/include/uapi/linux/serial.h
@@ -145,12 +145,13 @@ struct serial_rs485 {
 #define SER_RS485_ENABLED		_BITUL(0)
 #define SER_RS485_RTS_ON_SEND		_BITUL(1)
 #define SER_RS485_RTS_AFTER_SEND	_BITUL(2)
-#define SER_RS485_RX_DURING_TX		_BITUL(3)
-#define SER_RS485_TERMINATE_BUS		_BITUL(4)
-#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)
+/* Placeholder for bit 3: SER_RS485_RTS_BEFORE_SEND, which isn't used anymore */
+#define SER_RS485_RX_DURING_TX		_BITUL(4)
+#define SER_RS485_TERMINATE_BUS		_BITUL(5)
+#define SER_RS485_ADDRB			_BITUL(6)
+#define SER_RS485_ADDR_RECV		_BITUL(7)
+#define SER_RS485_ADDR_DEST		_BITUL(8)
+#define SER_RS485_MODE_RS422		_BITUL(9)
 
 	__u32	delay_rts_before_send;
 	__u32	delay_rts_after_send;
-- 
2.11.0