--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/linux-patch/orig-202007/ftdi_sio.c.patch	Sun Dec 06 01:20:27 2020 +0000
@@ -0,0 +1,150 @@
+--- ftdi_sio.c.orig	2016-06-24 09:18:38.000000000 -0800
++++ ftdi_sio.c	2020-07-28 15:33:04.022945400 -0800
+@@ -73,6 +73,8 @@
+ 				   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;
+@@ -83,15 +85,19 @@
+ struct ftdi_sio_quirk {
+ 	int (*probe)(struct usb_serial *);
+ 	/* Special settings for probed ports. */
+-	void (*port_probe)(struct ftdi_private *);
++	void (*port_probe)(struct usb_serial_port *, struct ftdi_private *);
+ };
+ 
+ static int   ftdi_jtag_probe(struct usb_serial *serial);
+ static int   ftdi_NDI_device_setup(struct usb_serial *serial);
+ static int   ftdi_stmclite_probe(struct usb_serial *serial);
+ static int   ftdi_8u2232c_probe(struct usb_serial *serial);
+-static void  ftdi_USB_UIRT_setup(struct ftdi_private *priv);
+-static void  ftdi_HE_TIRA1_setup(struct ftdi_private *priv);
++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 struct ftdi_sio_quirk ftdi_jtag_quirk = {
+ 	.probe	= ftdi_jtag_probe,
+@@ -117,6 +123,10 @@
+ 	.probe	= ftdi_8u2232c_probe,
+ };
+ 
++static 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:
+@@ -1008,6 +1018,13 @@
+ 	{ USB_DEVICE(ICPDAS_VID, ICPDAS_I7560U_PID) },
+ 	{ USB_DEVICE(ICPDAS_VID, ICPDAS_I7561U_PID) },
+ 	{ USB_DEVICE(ICPDAS_VID, ICPDAS_I7563U_PID) },
++	/* FreeCalypso USB adapters */
++	{ USB_DEVICE(FTDI_VID, FTDI_FALCONIA_JTAG_BUF_PID),
++		.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 */
+ };
+ 
+@@ -1804,7 +1821,7 @@
+ 	priv->flags = ASYNC_LOW_LATENCY;
+ 
+ 	if (quirk && quirk->port_probe)
+-		quirk->port_probe(priv);
++		quirk->port_probe(port, priv);
+ 
+ 	usb_set_serial_port_data(port, priv);
+ 
+@@ -1820,7 +1837,8 @@
+ /* Setup for the USB-UIRT device, which requires hardwired
+  * baudrate (38400 gets mapped to 312500) */
+ /* Called from usbserial:serial_probe */
+-static void ftdi_USB_UIRT_setup(struct ftdi_private *priv)
++static void ftdi_USB_UIRT_setup(struct usb_serial_port *port,
++				struct ftdi_private *priv)
+ {
+ 	priv->flags |= ASYNC_SPD_CUST;
+ 	priv->custom_divisor = 77;
+@@ -1830,7 +1848,8 @@
+ /* Setup for the HE-TIRA1 device, which requires hardwired
+  * baudrate (38400 gets mapped to 100000) and RTS-CTS enabled.  */
+ 
+-static void ftdi_HE_TIRA1_setup(struct ftdi_private *priv)
++static void ftdi_HE_TIRA1_setup(struct usb_serial_port *port,
++				struct ftdi_private *priv)
+ {
+ 	priv->flags |= ASYNC_SPD_CUST;
+ 	priv->custom_divisor = 240;
+@@ -1926,6 +1945,37 @@
+ 	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);
+@@ -1976,9 +2026,10 @@
+ 		}
+ 	}
+ 	/* 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);
+ }
+ 
+@@ -2316,7 +2367,8 @@
+ 			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);
+ 	}
+