serial: samsung: add support for manual RTS setting

The Samsung serial driver currently does not support setting the
RTS pin with an ioctl(TIOCMSET) call. This patch adds this support.

Changes in v2:
 - Preserve the RTS pin's manual setting  in set_termios() also when
   enabling CRTSCTS.

Signed-off-by: José Miguel Gonçalves <jose.goncalves@inov.pt>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 17 insertions, 3 deletions

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index 81f3dbabaaed..c1af04d46682 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -407,7 +407,14 @@ static unsigned int s3c24xx_serial_get_mctrl(struct uart_port *port)
 
 static void s3c24xx_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
-        /* todo - possibly remove AFC and do manual CTS */
+        unsigned int umcon = rd_regl(port, S3C2410_UMCON);
+
+        if (mctrl & TIOCM_RTS)
+                umcon |= S3C2410_UMCOM_RTS_LOW;
+        else
+                umcon &= ~S3C2410_UMCOM_RTS_LOW;
+
+        wr_regl(port, S3C2410_UMCON, umcon);
 }
 
 static void s3c24xx_serial_break_ctl(struct uart_port *port, int break_state)
@@ -774,8 +781,6 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
         if (termios->c_cflag & CSTOPB)
                 ulcon |= S3C2410_LCON_STOPB;
 
-        umcon = (termios->c_cflag & CRTSCTS) ? S3C2410_UMCOM_AFC : 0;
-
         if (termios->c_cflag & PARENB) {
                 if (termios->c_cflag & PARODD)
                         ulcon |= S3C2410_LCON_PODD;
@@ -792,6 +797,15 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
 
         wr_regl(port, S3C2410_ULCON, ulcon);
         wr_regl(port, S3C2410_UBRDIV, quot);
+
+        umcon = rd_regl(port, S3C2410_UMCON);
+        if (termios->c_cflag & CRTSCTS) {
+                umcon |= S3C2410_UMCOM_AFC;
+                /* Disable RTS when RX FIFO contains 63 bytes */
+                umcon &= ~S3C2412_UMCON_AFC_8;
+        } else {
+                umcon &= ~S3C2410_UMCOM_AFC;
+        }
         wr_regl(port, S3C2410_UMCON, umcon);
 
         if (ourport->info->has_divslot)