From 86d6b8c6f14382b97fd08a28c32f5790ebdec068 Mon Sep 17 00:00:00 2001 From: Karl Palsson Date: Tue, 18 Mar 2014 23:33:27 +0000 Subject: [PATCH] usb/serial/ch341: Add parity support Based on wireshark packet traces from a windows machine. ch340 and ch341 both seem to support all parity modes, but only the ch341 appears to support variable data bits and variable stop bits, so those are left unimplemented, as before. Tested on a generic usb-rs485 dongle with the chip label scratched off, and some Modbus/RTU devices that required various parity settings. Signed-off-by: Karl Palsson --- drivers/usb/serial/ch341.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c index e98590aab633..4f25aba5bdfc 100644 --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -358,6 +358,7 @@ static void ch341_set_termios(struct tty_struct *tty, struct ch341_private *priv = usb_get_serial_port_data(port); unsigned baud_rate; unsigned long flags; + unsigned int par_flags; baud_rate = tty_get_baud_rate(tty); @@ -368,10 +369,34 @@ static void ch341_set_termios(struct tty_struct *tty, /* Unimplemented: * (cflag & CSIZE) : data bits [5, 8] - * (cflag & PARENB) : parity {NONE, EVEN, ODD} * (cflag & CSTOPB) : stop bits [1, 2] */ + /* CH340 doesn't appear to support variable stop bits or data bits */ + if (C_PARENB(tty)) { + if (C_PARODD(tty)) { + if (tty->termios.c_cflag & CMSPAR) { + dev_dbg(&port->dev, "parity = mark\n"); + par_flags = 0xeb; + } else { + dev_dbg(&port->dev, "parity = odd\n"); + par_flags = 0xcb; + } + } else { + if (tty->termios.c_cflag & CMSPAR) { + dev_dbg(&port->dev, "parity = space\n"); + par_flags = 0xfb; + } else { + dev_dbg(&port->dev, "parity = even\n"); + par_flags = 0xdb; + } + } + } else { + dev_dbg(&port->dev, "parity = none\n"); + par_flags = 0xc3; + } + ch341_control_out(port->serial->dev, 0x9a, 0x2518, par_flags); + spin_lock_irqsave(&priv->lock, flags); if (C_BAUD(tty) == B0) priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS); -- 2.30.2