USB: serial: add support for serial port on the moschip 7715

Add support for the serial port on devices based on the MosChip 7715,
which provides a serial and parallel port on a single usb interface.
This is added to the existing driver for the Moschip 7720 dual serial
port device.  The 7715 is very similiar to the 7720, requiring only the
addition of a calc_num_ports() function, a separate interrupt-in
endpoint callback, and some manipulation of the port pointers added to
the attach() function to correct the fact that the usbserial core
erroneously assigns the first bulk in/out endpoint pair to the serial
port (the 7715 uses these for its parallel port).  There is no support
for the 7715's parallel port yet.
Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/mos7720.c

@@ -81,12 +81,15 @@ struct moschip_serial {
 
 static int debug;
 
+static struct usb_serial_driver moschip7720_2port_driver;
+
 #define USB_VENDOR_ID_MOSCHIP		0x9710
 #define MOSCHIP_DEVICE_ID_7720		0x7720
 #define MOSCHIP_DEVICE_ID_7715		0x7715
 
 static const struct usb_device_id moschip_port_id_table[] = {
 	{ USB_DEVICE(USB_VENDOR_ID_MOSCHIP, MOSCHIP_DEVICE_ID_7720) },
+	{ USB_DEVICE(USB_VENDOR_ID_MOSCHIP, MOSCHIP_DEVICE_ID_7715) },
 	{ } /* terminating entry */
 };
 MODULE_DEVICE_TABLE(usb, moschip_port_id_table);
@@ -185,6 +188,75 @@ exit:
 	return;
 }
 
+/*
+ * mos7715_interrupt_callback
+ *	this is the 7715's callback function for when we have received data on
+ *	the interrupt endpoint.
+ */
+static void mos7715_interrupt_callback(struct urb *urb)
+{
+	int result;
+	int length;
+	int status = urb->status;
+	__u8 *data;
+	__u8 iir;
+
+	switch (status) {
+	case 0:
+		/* success */
+		break;
+	case -ECONNRESET:
+	case -ENOENT:
+	case -ESHUTDOWN:
+		/* this urb is terminated, clean up */
+		dbg("%s - urb shutting down with status: %d", __func__,
+		    status);
+		return;
+	default:
+		dbg("%s - nonzero urb status received: %d", __func__,
+		    status);
+		goto exit;
+	}
+
+	length = urb->actual_length;
+	data = urb->transfer_buffer;
+
+	/* Structure of data from 7715 device:
+	 * Byte 1: IIR serial Port
+	 * Byte 2: unused
+	 * Byte 2: DSR parallel port
+	 * Byte 4: FIFO status for both */
+
+	if (unlikely(length != 4)) {
+		dbg("Wrong data !!!");
+		return;
+	}
+
+	iir = data[0];
+	if (!(iir & 0x01)) {	/* serial port interrupt pending */
+		switch (iir & 0x0f) {
+		case SERIAL_IIR_RLS:
+			dbg("Serial Port: Receiver status error or address "
+			    "bit detected in 9-bit mode\n");
+			break;
+		case SERIAL_IIR_CTI:
+			dbg("Serial Port: Receiver time out");
+			break;
+		case SERIAL_IIR_MS:
+			dbg("Serial Port: Modem status change");
+			break;
+		}
+	}
+
+exit:
+	result = usb_submit_urb(urb, GFP_ATOMIC);
+	if (result)
+		dev_err(&urb->dev->dev,
+			"%s - Error %d submitting control urb\n",
+			__func__, result);
+	return;
+}
+
 /*
  * mos7720_bulk_in_callback
  *	this is the callback function for when we have received data on the
@@ -283,7 +355,7 @@ static int send_mos_cmd(struct usb_serial *serial, __u8 request, __u16 value,
 
 	if (value < MOS_MAX_PORT) {
 		if (product == MOSCHIP_DEVICE_ID_7715)
-			value = value*0x100+0x100;
+			value = 0x0200; /* identifies the 7715's serial port */
 		else
 			value = value*0x100+0x200;
 	} else {
@@ -319,6 +391,35 @@ out:
 	return status;
 }
 
+
+/*
+ * mos77xx_probe
+ *	this function installs the appropriate read interrupt endpoint callback
+ *	depending on whether the device is a 7720 or 7715, thus avoiding costly
+ *	run-time checks in the high-frequency callback routine itself.
+ */
+static int mos77xx_probe(struct usb_serial *serial,
+			 const struct usb_device_id *id)
+{
+	if (id->idProduct == MOSCHIP_DEVICE_ID_7715)
+		moschip7720_2port_driver.read_int_callback =
+			mos7715_interrupt_callback;
+	else
+		moschip7720_2port_driver.read_int_callback =
+			mos7720_interrupt_callback;
+
+	return 0;
+}
+
+static int mos77xx_calc_num_ports(struct usb_serial *serial)
+{
+	u16 product = le16_to_cpu(serial->dev->descriptor.idProduct);
+	if (product == MOSCHIP_DEVICE_ID_7715)
+		return 1;
+
+	return 2;
+}
+
 static int mos7720_open(struct tty_struct *tty, struct usb_serial_port *port)
 {
 	struct usb_serial *serial;
@@ -1495,6 +1596,7 @@ static int mos7720_startup(struct usb_serial *serial)
 	struct usb_device *dev;
 	int i;
 	char data;
+	u16 product = le16_to_cpu(serial->dev->descriptor.idProduct);
 
 	dbg("%s: Entering ..........", __func__);
 
@@ -1514,6 +1616,29 @@ static int mos7720_startup(struct usb_serial *serial)
 
 	usb_set_serial_data(serial, mos7720_serial);
 
+	/*
+	 * The 7715 uses the first bulk in/out endpoint pair for the parallel
+	 * port, and the second for the serial port.  Because the usbserial core
+	 * assumes both pairs are serial ports, we must engage in a bit of
+	 * subterfuge and swap the pointers for ports 0 and 1 in order to make
+	 * port 0 point to the serial port.  However, both moschip devices use a
+	 * single interrupt-in endpoint for both ports (as mentioned a little
+	 * further down), and this endpoint was assigned to port 0.  So after
+	 * the swap, we must copy the interrupt endpoint elements from port 1
+	 * (as newly assigned) to port 0, and null out port 1 pointers.
+	 */
+	if (product == MOSCHIP_DEVICE_ID_7715) {
+		struct usb_serial_port *tmp = serial->port[0];
+		serial->port[0] = serial->port[1];
+		serial->port[1] = tmp;
+		serial->port[0]->interrupt_in_urb = tmp->interrupt_in_urb;
+		serial->port[0]->interrupt_in_buffer = tmp->interrupt_in_buffer;
+		serial->port[0]->interrupt_in_endpointAddress =
+			tmp->interrupt_in_endpointAddress;
+		serial->port[1]->interrupt_in_urb = NULL;
+		serial->port[1]->interrupt_in_buffer = NULL;
+	}
+
 	/* we set up the pointers to the endpoints in the mos7720_open *
 	 * function, as the structures aren't created yet.             */
 
@@ -1529,7 +1654,7 @@ static int mos7720_startup(struct usb_serial *serial)
 
 		/* Initialize all port interrupt end point to port 0 int
 		 * endpoint.  Our device has only one interrupt endpoint
-		 * comman to all ports */
+		 * common to all ports */
 		serial->port[i]->interrupt_in_endpointAddress =
 				serial->port[0]->interrupt_in_endpointAddress;
 
@@ -1584,11 +1709,12 @@ static struct usb_serial_driver moschip7720_2port_driver = {
 	.description		= "Moschip 2 port adapter",
 	.usb_driver		= &usb_driver,
 	.id_table		= moschip_port_id_table,
-	.num_ports		= 2,
+	.calc_num_ports		= mos77xx_calc_num_ports,
 	.open			= mos7720_open,
 	.close			= mos7720_close,
 	.throttle		= mos7720_throttle,
 	.unthrottle		= mos7720_unthrottle,
+	.probe			= mos77xx_probe,
 	.attach			= mos7720_startup,
 	.release		= mos7720_release,
 	.ioctl			= mos7720_ioctl,
@@ -1600,7 +1726,7 @@ static struct usb_serial_driver moschip7720_2port_driver = {
 	.chars_in_buffer	= mos7720_chars_in_buffer,
 	.break_ctl		= mos7720_break,
 	.read_bulk_callback	= mos7720_bulk_in_callback,
-	.read_int_callback	= mos7720_interrupt_callback,
+	.read_int_callback	= NULL  /* dynamically assigned in probe() */
 };
 
 static int __init moschip7720_init(void)