[PATCH v4 08/13] USB: ch341: add support for RTS/CTS flow control

Grigori Goronzy
2016-04-15T21:17:28Z

v2: use correct flag variable.
v3: fix compilation

Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
drivers/usb/serial/ch341.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index e475677..7ca21a1 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -68,6 +68,7 @@
#define CH341_REQ_READ_REG 0x95
#define CH341_REG_BREAK1 0x05
#define CH341_REG_LCR 0x18
+#define CH341_REG_RTSCTS 0x27
#define CH341_NBREAK_BITS_REG1 0x01

#define CH341_LCR_ENABLE_RX 0x80
@@ -399,6 +400,16 @@ static void ch341_set_termios(struct tty_struct *tty,

ch341_set_handshake(port->serial->dev, priv->line_control);

+ if (C_CRTSCTS(tty)) {
+ r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
+ CH341_REG_RTSCTS | ((uint16_t)CH341_REG_RTSCTS << 8),
+ 0x0101);
+ if (r < 0) {
+ dev_err(&port->dev, "%s - USB control write error (%d)\n",
+ __func__, r);
+ tty->termios.c_cflag &= ~CRTSCTS;
+ }
+ }
}

static void ch341_break_ctl(struct tty_struct *tty, int break_state)
--
1.9.1