| Message ID | 20210118111331.5048-2-johan@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/6] USB: serial: cp210x: add support for software flow control | expand |
On Mon, Jan 18, 2021 at 12:13:26PM +0100, Johan Hovold wrote: > From: Wang Sheng Long <shenglong.wang.ext@siemens.com> > > When data is transmitted between two serial ports, the phenomenon of > data loss often occurs. The two kinds of flow control commonly used in > serial communication are hardware flow control and software flow > control. > > In serial communication, If you only use RX/TX/GND Pins, you can't do > hardware flow. So we often used software flow control and prevent data > loss. The user sets the software flow control through the application > program, and the application program sets the software flow control mode > for the serial port chip through the driver. > > For the cp210 serial port chip, its driver lacks the software flow > control setting code, so the user cannot set the software flow control > function through the application program. This adds the missing software > flow control. > > Signed-off-by: Wang Sheng Long <shenglong.wang.ext@siemens.com> > Link: https://lore.kernel.org/r/20210104094502.3942-1-china_shenglong@163.com > [ johan: rework properly on top of recent termios changes ] > Signed-off-by: Johan Hovold <johan@kernel.org> > --- > drivers/usb/serial/cp210x.c | 67 +++++++++++++++++++++++++++++++++++-- > 1 file changed, 65 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c > index fbb10dfc56e3..5bd14770065b 100644 > --- a/drivers/usb/serial/cp210x.c > +++ b/drivers/usb/serial/cp210x.c > @@ -377,6 +377,16 @@ static struct usb_serial_driver * const serial_drivers[] = { > #define CONTROL_WRITE_DTR 0x0100 > #define CONTROL_WRITE_RTS 0x0200 > > +/* CP210X_(GET|SET)_CHARS */ > +struct cp210x_special_chars { > + u8 bEofChar; > + u8 bErrorChar; > + u8 bBreakChar; > + u8 bEventChar; > + u8 bXonChar; > + u8 bXoffChar; > +}; > + > /* CP210X_VENDOR_SPECIFIC values */ > #define CP210X_READ_2NCONFIG 0x000E > #define CP210X_READ_LATCH 0x00C2 > @@ -1074,11 +1084,38 @@ static void cp210x_disable_event_mode(struct usb_serial_port *port) > port_priv->event_mode = false; > } > > +static int cp210x_set_chars(struct usb_serial_port *port, > + struct cp210x_special_chars *chars) > +{ > + struct cp210x_port_private *port_priv = usb_get_serial_port_data(port); > + struct usb_serial *serial = port->serial; > + void *dmabuf; > + int result; > + > + dmabuf = kmemdup(chars, sizeof(*chars), GFP_KERNEL); > + if (!dmabuf) > + return -ENOMEM; > + > + result = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0), > + CP210X_SET_CHARS, REQTYPE_HOST_TO_INTERFACE, 0, > + port_priv->bInterfaceNumber, > + dmabuf, sizeof(*chars), USB_CTRL_SET_TIMEOUT); > + > + kfree(dmabuf); > + > + if (result < 0) { > + dev_err(&port->dev, "failed to set special chars: %d\n", result); > + return result; > + } This is an "open coded" usb_control_msg_send() call :) Other than that minor thing: Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
On Mon, Jan 18, 2021 at 01:42:59PM +0100, Greg Kroah-Hartman wrote: > On Mon, Jan 18, 2021 at 12:13:26PM +0100, Johan Hovold wrote: > > From: Wang Sheng Long <shenglong.wang.ext@siemens.com> > > +static int cp210x_set_chars(struct usb_serial_port *port, > > + struct cp210x_special_chars *chars) > > +{ > > + struct cp210x_port_private *port_priv = usb_get_serial_port_data(port); > > + struct usb_serial *serial = port->serial; > > + void *dmabuf; > > + int result; > > + > > + dmabuf = kmemdup(chars, sizeof(*chars), GFP_KERNEL); > > + if (!dmabuf) > > + return -ENOMEM; > > + > > + result = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0), > > + CP210X_SET_CHARS, REQTYPE_HOST_TO_INTERFACE, 0, > > + port_priv->bInterfaceNumber, > > + dmabuf, sizeof(*chars), USB_CTRL_SET_TIMEOUT); > > + > > + kfree(dmabuf); > > + > > + if (result < 0) { > > + dev_err(&port->dev, "failed to set special chars: %d\n", result); > > + return result; > > + } > > This is an "open coded" usb_control_msg_send() call :) Right, but there are a few more functions like this one in this driver so I kept it for consistency for now. > Other than that minor thing: > > Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Thanks for reviewing all of these. Now applied. Johan
diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c index fbb10dfc56e3..5bd14770065b 100644 --- a/drivers/usb/serial/cp210x.c +++ b/drivers/usb/serial/cp210x.c @@ -377,6 +377,16 @@ static struct usb_serial_driver * const serial_drivers[] = { #define CONTROL_WRITE_DTR 0x0100 #define CONTROL_WRITE_RTS 0x0200 +/* CP210X_(GET|SET)_CHARS */ +struct cp210x_special_chars { + u8 bEofChar; + u8 bErrorChar; + u8 bBreakChar; + u8 bEventChar; + u8 bXonChar; + u8 bXoffChar; +}; + /* CP210X_VENDOR_SPECIFIC values */ #define CP210X_READ_2NCONFIG 0x000E #define CP210X_READ_LATCH 0x00C2 @@ -1074,11 +1084,38 @@ static void cp210x_disable_event_mode(struct usb_serial_port *port) port_priv->event_mode = false; } +static int cp210x_set_chars(struct usb_serial_port *port, + struct cp210x_special_chars *chars) +{ + struct cp210x_port_private *port_priv = usb_get_serial_port_data(port); + struct usb_serial *serial = port->serial; + void *dmabuf; + int result; + + dmabuf = kmemdup(chars, sizeof(*chars), GFP_KERNEL); + if (!dmabuf) + return -ENOMEM; + + result = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0), + CP210X_SET_CHARS, REQTYPE_HOST_TO_INTERFACE, 0, + port_priv->bInterfaceNumber, + dmabuf, sizeof(*chars), USB_CTRL_SET_TIMEOUT); + + kfree(dmabuf); + + if (result < 0) { + dev_err(&port->dev, "failed to set special chars: %d\n", result); + return result; + } + + return 0; +} + static bool cp210x_termios_change(const struct ktermios *a, const struct ktermios *b) { bool iflag_change; - iflag_change = ((a->c_iflag ^ b->c_iflag) & INPCK); + iflag_change = ((a->c_iflag ^ b->c_iflag) & (INPCK | IXON | IXOFF)); return tty_termios_hw_change(a, b) || iflag_change; } @@ -1086,13 +1123,29 @@ static bool cp210x_termios_change(const struct ktermios *a, const struct ktermio static void cp210x_set_flow_control(struct tty_struct *tty, struct usb_serial_port *port, struct ktermios *old_termios) { + struct cp210x_special_chars chars; struct cp210x_flow_ctl flow_ctl; u32 flow_repl; u32 ctl_hs; int ret; - if (old_termios && C_CRTSCTS(tty) == (old_termios->c_cflag & CRTSCTS)) + if (old_termios && + C_CRTSCTS(tty) == (old_termios->c_cflag & CRTSCTS) && + I_IXON(tty) == (old_termios->c_iflag & IXON) && + I_IXOFF(tty) == (old_termios->c_iflag & IXOFF)) { return; + } + + if (I_IXON(tty) || I_IXOFF(tty)) { + memset(&chars, 0, sizeof(chars)); + + chars.bXonChar = START_CHAR(tty); + chars.bXoffChar = STOP_CHAR(tty); + + ret = cp210x_set_chars(port, &chars); + if (ret) + return; + } ret = cp210x_read_reg_block(port, CP210X_GET_FLOW, &flow_ctl, sizeof(flow_ctl)); @@ -1118,6 +1171,16 @@ static void cp210x_set_flow_control(struct tty_struct *tty, flow_repl |= CP210X_SERIAL_RTS_SHIFT(CP210X_SERIAL_RTS_ACTIVE); } + if (I_IXOFF(tty)) + flow_repl |= CP210X_SERIAL_AUTO_RECEIVE; + else + flow_repl &= ~CP210X_SERIAL_AUTO_RECEIVE; + + if (I_IXON(tty)) + flow_repl |= CP210X_SERIAL_AUTO_TRANSMIT; + else + flow_repl &= ~CP210X_SERIAL_AUTO_TRANSMIT; + dev_dbg(&port->dev, "%s - ulControlHandshake=0x%08x, ulFlowReplace=0x%08x\n", __func__, ctl_hs, flow_repl);