[PATCH v2 07/14] USB: ch341: add support for parity, frame length, stop bits

[Grigori Goronzy]

With the new reinitialization method, configuring parity, different
frame lengths and different stop bit settings work as expected on
both CH340G and CH341A.  This has been extensively tested with a
logic analyzer.

Tested-by: Ryan Barber <rfb@xxxxxxxxxxxxx>
Signed-off-by: Grigori Goronzy <greg@xxxxxxxxxxxx>
---
 drivers/usb/serial/ch341.c | 36 ++++++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index c001773..4d66f0f 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -346,6 +346,7 @@ static void ch341_set_termios(struct tty_struct *tty,
 	unsigned baud_rate;
 	unsigned long flags;
 	unsigned char ctrl;
+	unsigned cflag = tty->termios.c_cflag;
 	int r;
 
 	/* redundant changes may cause the chip to lose bytes */
@@ -356,7 +357,35 @@ static void ch341_set_termios(struct tty_struct *tty,
 
 	priv->baud_rate = baud_rate;
 
-	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
+	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
+
+	switch (cflag & CSIZE) {
+	case CS5:
+		ctrl |= CH341_LCR_CS5;
+		break;
+	case CS6:
+		ctrl |= CH341_LCR_CS6;
+		break;
+	case CS7:
+		ctrl |= CH341_LCR_CS7;
+		break;
+	case CS8:
+	default:
+		ctrl |= CH341_LCR_CS8;
+		break;
+	}
+
+	if (cflag & PARENB) {
+		ctrl |= CH341_LCR_ENABLE_PAR;
+		if ((cflag & PARODD) == 0)
+			ctrl |= CH341_LCR_PAR_EVEN;
+	}
+
+	if (cflag & CMSPAR)
+		ctrl |= CH341_LCR_MARK_SPACE;
+
+	if (cflag & CSTOPB)
+		ctrl |= CH341_LCR_STOP_BITS_2;
 
 	if (baud_rate) {
 		spin_lock_irqsave(&priv->lock, flags);
@@ -373,11 +402,6 @@ static void ch341_set_termios(struct tty_struct *tty,
 
 	ch341_set_handshake(port->serial->dev, priv->line_control);
 
-	/* Unimplemented:
-	 * (cflag & CSIZE) : data bits [5, 8]
-	 * (cflag & PARENB) : parity {NONE, EVEN, ODD}
-	 * (cflag & CSTOPB) : stop bits [1, 2]
-	 */
 }
 
 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
-- 
1.9.1