[PATCH 3/8] serial: 8250: save rs485_flags per instance

[Wolfram Sang <w.sang@pengutronix.de>]

This avoids mangling with registers when reading the RS485 status via IOCTL.
Also, features can check their configuration at runtime which will be needed
for a later patch.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
---
 drivers/tty/serial/8250.c |   16 +++++-----------
 1 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
index 920b4df..b5d3248 100644
--- a/drivers/tty/serial/8250.c
+++ b/drivers/tty/serial/8250.c
@@ -154,6 +154,7 @@ struct uart_8250_port {
 	unsigned char		lsr_saved_flags;
 #define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
 	unsigned char		msr_saved_flags;
+	__u32			rs485_flags;	/* copied from IOCTL */
 };
 
 struct irq_info {
@@ -2729,28 +2730,21 @@ static int serial8250_ioctl_port(struct uart_port *port,
 		serial_outp(up, UART_FCTR, fctr);
 		serial_outp(up, UART_LCR, lcr);
 		spin_unlock_irqrestore(&up->port.lock, flags);
+
+		up->rs485_flags = rs485ctrl.flags;
+
 		return 0;
 	}
 
 	case TIOCGRS485:
 	{
 		struct serial_rs485 rs485ctrl;
-		unsigned char lcr;
 
 		if (port->type != PORT_16850)
 			return -ENOTTY;
 
 		memset(&rs485ctrl, 0, sizeof(rs485ctrl));
-
-		spin_lock_irqsave(&up->port.lock, flags);
-		lcr = serial_inp(up, UART_LCR);
-		serial_outp(up, UART_LCR, UART_LCR_CONF_MODE_B);
-		if (serial_inp(up, UART_FCTR) & UART_FCTR_RS485)
-			rs485ctrl.flags = SER_RS485_ENABLED;
-		else
-			rs485ctrl.flags = 0;
-		serial_outp(up, UART_LCR, lcr);
-		spin_unlock_irqrestore(&up->port.lock, flags);
+		rs485ctrl.flags = up->rs485_flags;
 
 		if (copy_to_user((struct serial_rs485 *)arg, &rs485ctrl,
 				 sizeof(rs485ctrl)))
-- 
1.7.7.1