linux-kernel - [PATCH v4 06/13] USB: ch341: add support for parity, frame length, stop bits

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Date:	Fri, 15 Apr 2016 23:14:09 +0200
From:	Grigori Goronzy <greg@...wn.ath.cx>
To:	Johan Hovold <johan@...nel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Grigori Goronzy <greg@...wn.ath.cx>
Subject: [PATCH v4 06/13] USB: ch341: add support for parity, frame length, stop bits

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.

v2: only set mark/space when parity is enabled, simplifications,
patch termios HW flags.
v3: fix parity odd/even regression.

Tested-by: Ryan Barber <rfb@...scraper.nu>
Signed-off-by: Grigori Goronzy <greg@...wn.ath.cx>
---
 drivers/usb/serial/ch341.c | 40 ++++++++++++++++++++++++++++++----------
 1 file changed, 30 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 6181616..2fbec4a 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -341,7 +341,6 @@ static void ch341_set_termios(struct tty_struct *tty,
 		struct usb_serial_port *port, struct ktermios *old_termios)
 {
 	struct ch341_private *priv = usb_get_serial_port_data(port);
-	unsigned baud_rate;
 	unsigned long flags;
 	unsigned char ctrl;
 	int r;
@@ -350,13 +349,39 @@ static void ch341_set_termios(struct tty_struct *tty,
 	if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
 		return;
 
-	baud_rate = tty_get_baud_rate(tty);
+	priv->baud_rate = tty_get_baud_rate(tty);
 
-	priv->baud_rate = baud_rate;
+	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
 
-	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
+	switch (C_CSIZE(tty)) {
+	case CS5:
+		ctrl |= CH341_LCR_CS5;
+		break;
+	case CS6:
+		ctrl |= CH341_LCR_CS6;
+		break;
+	case CS7:
+		ctrl |= CH341_LCR_CS7;
+		break;
+	default:
+		tty->termios.c_cflag |= CS8;
+	case CS8:
+		ctrl |= CH341_LCR_CS8;
+		break;
+	}
+
+	if (C_PARENB(tty)) {
+		ctrl |= CH341_LCR_ENABLE_PAR;
+		if (C_PARODD(tty) == 0)
+			ctrl |= CH341_LCR_PAR_EVEN;
+		if (C_CMSPAR(tty))
+			ctrl |= CH341_LCR_MARK_SPACE;
+	}
+
+	if (C_CSTOPB(tty))
+		ctrl |= CH341_LCR_STOP_BITS_2;
 
-	if (baud_rate) {
+	if (priv->baud_rate) {
 		spin_lock_irqsave(&priv->lock, flags);
 		priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
 		spin_unlock_irqrestore(&priv->lock, flags);
@@ -373,11 +398,6 @@ 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