cp210x.patch

--- a/cp210x.c	2013-10-30 18:43:43.000000000 -0600
+++ b/cp210x.c	2013-10-30 19:23:02.410147064 -0600
@@ -31,6 +31,8 @@
  */
 static int cp210x_open(struct tty_struct *tty, struct usb_serial_port *);
 static void cp210x_close(struct usb_serial_port *);
+static int cp210x_ioctl(struct tty_struct *tty,
+	unsigned int cmd, unsigned long arg);
 static void cp210x_get_termios(struct tty_struct *, struct usb_serial_port *);
 static void cp210x_get_termios_port(struct usb_serial_port *port,
 	unsigned int *cflagp, unsigned int *baudp);
@@ -174,6 +176,7 @@
 	.bulk_out_size		= 256,
 	.open			= cp210x_open,
 	.close			= cp210x_close,
+	.ioctl			= cp210x_ioctl,
 	.break_ctl		= cp210x_break_ctl,
 	.set_termios		= cp210x_set_termios,
 	.tiocmget		= cp210x_tiocmget,
@@ -187,6 +190,10 @@
 	&cp210x_device, NULL
 };
 
+/* IOCTLs */
+#define IOCTL_GPIOGET	 0x8000
+#define IOCTL_GPIOSET	 0x8001
+
 /* Config request types */
 #define REQTYPE_HOST_TO_INTERFACE	0x41
 #define REQTYPE_INTERFACE_TO_HOST	0xc1
@@ -220,11 +227,16 @@
 #define CP210X_SET_CHARS	0x19
 #define CP210X_GET_BAUDRATE	0x1D
 #define CP210X_SET_BAUDRATE	0x1E
+#define CP210X_VENDOR_SPECIFIC	0xFF
 
 /* CP210X_IFC_ENABLE */
 #define UART_ENABLE		0x0001
 #define UART_DISABLE		0x0000
 
+/* CP210X_VENDOR_SPECIFIC */
+#define CP210X_WRITE_LATCH	0x37E1
+#define CP210X_READ_LATCH	0x00C2
+
 /* CP210X_(SET|GET)_BAUDDIV */
 #define BAUD_RATE_GEN_FREQ	0x384000
 
@@ -449,6 +461,54 @@
 	mutex_unlock(&port->serial->disc_mutex);
 }
 
+static int cp210x_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
+{
+	struct usb_serial_port *port = tty->driver_data;
+	struct usb_serial *serial = port->serial;
+	int result = 0;
+	struct cp210x_serial_private *spriv = usb_get_serial_data(serial);
+	unsigned int latch_setting = 0;
+
+	switch (cmd) {
+	    case IOCTL_GPIOGET:
+		result = usb_control_msg(
+			      serial->dev,
+			      usb_rcvctrlpipe(serial->dev, 0),
+			      CP210X_VENDOR_SPECIFIC,
+			      REQTYPE_DEVICE_TO_HOST,
+			      CP210X_READ_LATCH,
+			      spriv->bInterfaceNumber,
+			      &latch_setting, 1,
+			      USB_CTRL_GET_TIMEOUT);
+		if (result != 1)
+		    return -EPROTO;
+		*(unsigned long *)arg = (unsigned long)latch_setting;
+		return 0;
+	    break;
+	    case IOCTL_GPIOSET:
+		latch_setting = *(unsigned int *)arg & 0x000000FF;
+		//why [23:16] bits are taken for value is unknown
+		latch_setting |= (*(unsigned int *)arg & 0x00FF0000) >> 8;
+		
+		result = usb_control_msg(
+			      serial->dev,
+			      usb_sndctrlpipe(serial->dev, 0),
+			      CP210X_VENDOR_SPECIFIC,
+			      REQTYPE_HOST_TO_DEVICE,
+			      CP210X_WRITE_LATCH,
+			      latch_setting,
+			      NULL, 0,
+			      USB_CTRL_SET_TIMEOUT);
+		if (result != 0)
+		    return -EPROTO;
+		return 0;
+	    break;
+	    default:
+	    break;
+	}
+	return -ENOIOCTLCMD;
+}
+
 /*
  * cp210x_get_termios
  * Reads the baud rate, data bits, parity, stop bits and flow control mode