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| From 826333457d90018641883265a672268e1b13ab93 Mon Sep 17 00:00:00 2001 | |
| From: Karl Palsson <karlp@tweak.net.au> | |
| 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 <karlp@tweak.net.au> | |
| --- | |
| 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 82371f6..afd2ec4 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, | |
| 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); | |
| @@ -366,9 +367,33 @@ 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); | |
| + | |
| } | |
| static void ch341_break_ctl(struct tty_struct *tty, int break_state) | |
| -- | |
| 1.8.3.1 | |