FreeCalypso DUART28C is an FT2232D-based USB to dual UART adapter
with a special quirk: Channel B RTS and DTR outputs (BDBUS2 and BDBUS4
on the chip) have been repurposed to drive power and reset controls
on Calypso targets. The circuit is wired such that BDBUS[24] high
(RTS/DTR inactive) is the normal state with power/reset control
NOT activated, whereas BDBUS[24] low (RTS or DTR active) turn ON
the corresponding power/reset control drivers.
A special ftdi_sio driver quirk is needed in order to suppress
automatic assertion of DTR & RTS on device open: this device's
special power and reset control drivers MUST NOT be activated
when the port is ordinarily opened for plain serial communication,
instead they must only be activated when a special userspace
application explicitly requests such activation with a TIOCMBIS ioctl.
The special quirk is conditionalized on the DUART28C adapter's custom
USB ID, and is further limited to FT2232D Channel B only: Channel A
is wired normally, with the chip's ADBUS2 and ADBUS4 outputs
actually being RTS and DTR rather than something else.
Signed-off-by: Mychaela N. Falconia <falcon@xxxxxxxxxxxxxxx>
---
drivers/usb/serial/ftdi_sio.c | 51 +++++++++++++++++++++++++++++++++++++++----
1 file changed, 47 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index cdf4f4e05fb2..73c6b4e2c3e4 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -69,6 +69,8 @@ struct ftdi_private {
this value */
int force_rtscts; /* if non-zero, force RTS-CTS to always
be enabled */
+ int no_auto_dtr_rts; /* if non-zero, suppress automatic assertion
+ of DTR & RTS on device open */
unsigned int latency; /* latency setting in use */
unsigned short max_packet_size;
@@ -99,6 +101,8 @@ static void ftdi_USB_UIRT_setup(struct usb_serial_port *port,
struct ftdi_private *priv);
static void ftdi_HE_TIRA1_setup(struct usb_serial_port *port,
struct ftdi_private *priv);
+static void ftdi_duart28c_setup(struct usb_serial_port *port,
+ struct ftdi_private *priv);
static const struct ftdi_sio_quirk ftdi_jtag_quirk = {
.probe = ftdi_jtag_probe,
@@ -124,6 +128,10 @@ static const struct ftdi_sio_quirk ftdi_8u2232c_quirk = {
.probe = ftdi_8u2232c_probe,
};
+static const struct ftdi_sio_quirk ftdi_duart28c_quirk = {
+ .port_probe = ftdi_duart28c_setup,
+};
+
/*
* The 8U232AM has the same API as the sio except for:
* - it can support MUCH higher baudrates; up to:
@@ -1044,6 +1052,8 @@ static const struct usb_device_id id_table_combined[] = {
.driver_info = (kernel_ulong_t)&ftdi_jtag_quirk },
{ USB_DEVICE(FTDI_VID, FTDI_FALCONIA_JTAG_UNBUF_PID),
.driver_info = (kernel_ulong_t)&ftdi_jtag_quirk },
+ { USB_DEVICE(FTDI_VID, FTDI_FALCONIA_DUART28C_PID),
+ .driver_info = (kernel_ulong_t)&ftdi_duart28c_quirk },
{ } /* Terminating entry */
};
@@ -2388,6 +2398,37 @@ static int ftdi_stmclite_probe(struct usb_serial *serial)
return 0;
}
+/*
+ * FreeCalypso DUART28C is an FT2232D-based USB to dual UART adapter
+ * with a special quirk: Channel B RTS and DTR outputs (BDBUS2 and BDBUS4
+ * on the chip) have been repurposed to drive power and reset controls
+ * on Calypso targets. The circuit is wired such that BDBUS[24] high
+ * (RTS/DTR inactive) is the normal state with power/reset control
+ * NOT activated, whereas BDBUS[24] low (RTS or DTR active) turn ON
+ * the corresponding power/reset control drivers.
+ *
+ * A special ftdi_sio driver quirk is needed in order to suppress
+ * automatic assertion of DTR & RTS on device open: this device's
+ * special power and reset control drivers MUST NOT be activated
+ * when the port is ordinarily opened for plain serial communication,
+ * instead they must only be activated when a special userspace
+ * application explicitly requests such activation with a TIOCMBIS ioctl.
+ *
+ * The special quirk must be applied only to FT2232D Channel B:
+ * Channel A is wired normally, with the chip's ADBUS2 and ADBUS4 outputs
+ * actually being RTS and DTR rather than something else.
+ */
+static void ftdi_duart28c_setup(struct usb_serial_port *port,
+ struct ftdi_private *priv)
+{
+ struct usb_serial *serial = port->serial;
+ struct usb_device *udev = serial->dev;
+ struct usb_interface *interface = serial->interface;
+
+ if (interface == udev->actconfig->interface[1])
+ priv->no_auto_dtr_rts = 1;
+}
+
static int ftdi_sio_port_remove(struct usb_serial_port *port)
{
struct ftdi_private *priv = usb_get_serial_port_data(port);
@@ -2440,9 +2481,10 @@ static void ftdi_dtr_rts(struct usb_serial_port *port, int on)
}
}
/* drop RTS and DTR */
- if (on)
- set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
- else
+ if (on) {
+ if (!priv->no_auto_dtr_rts)
+ set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
+ } else
clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
}
@@ -2790,7 +2832,8 @@ static void ftdi_set_termios(struct tty_struct *tty,
dev_err(ddev, "%s urb failed to set baudrate\n", __func__);
mutex_unlock(&priv->cfg_lock);
/* Ensure RTS and DTR are raised when baudrate changed from 0 */
- if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
+ if (old_termios && (old_termios->c_cflag & CBAUD) == B0
+ && !priv->no_auto_dtr_rts)
set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
}
--
2.9.0
