serial: 8250: Create serial8250_em485_supported for em485 users

Create serial8250_em485_supported for the serial_rs485 features
supported by the em485 framework.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-5-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250.h

@@ -207,6 +207,7 @@ int serial8250_em485_config(struct uart_port *port, struct serial_rs485 *rs485);
 void serial8250_em485_start_tx(struct uart_8250_port *p);
 void serial8250_em485_stop_tx(struct uart_8250_port *p);
 void serial8250_em485_destroy(struct uart_8250_port *p);
+extern struct serial_rs485 serial8250_em485_supported;
 
 /* MCR <-> TIOCM conversion */
 static inline int serial8250_TIOCM_to_MCR(int tiocm)

drivers/tty/serial/8250/8250_port.c

@@ -647,6 +647,14 @@ void serial8250_em485_destroy(struct uart_8250_port *p)
 }
 EXPORT_SYMBOL_GPL(serial8250_em485_destroy);
 
+struct serial_rs485 serial8250_em485_supported = {
+	.flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | SER_RS485_RTS_AFTER_SEND |
+		 SER_RS485_TERMINATE_BUS | SER_RS485_RX_DURING_TX,
+	.delay_rts_before_send = 1,
+	.delay_rts_after_send = 1,
+};
+EXPORT_SYMBOL_GPL(serial8250_em485_supported);
+
 /**
  * serial8250_em485_config() - generic ->rs485_config() callback
  * @port: uart port