serial: 8250_pci: Don't fail on multiport card class

Do not fail on multiport cards in serial_pci_is_class_communication().

It restores behaviour for SUNIX multiport cards, that enumerated by
class and have a custom board data.

Moreover it allows users to reenumerate port-by-port from user space.

Fixes: 7d8905d06405 ("serial: 8250_pci: Enable device after we check black list")
Reported-by: Nikola Ciprich <nikola.ciprich@linuxbox.cz>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Nikola Ciprich <nikola.ciprich@linuxbox.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_pci.c

@@ -3387,11 +3387,9 @@ static int serial_pci_is_class_communication(struct pci_dev *dev)
 	/*
 	 * If it is not a communications device or the programming
 	 * interface is greater than 6, give up.
-	 *
-	 * (Should we try to make guesses for multiport serial devices
-	 * later?)
 	 */
 	if ((((dev->class >> 8) != PCI_CLASS_COMMUNICATION_SERIAL) &&
+	     ((dev->class >> 8) != PCI_CLASS_COMMUNICATION_MULTISERIAL) &&
 	     ((dev->class >> 8) != PCI_CLASS_COMMUNICATION_MODEM)) ||
 	    (dev->class & 0xff) > 6)
 		return -ENODEV;
@@ -3428,6 +3426,12 @@ serial_pci_guess_board(struct pci_dev *dev, struct pciserial_board *board)
 {
 	int num_iomem, num_port, first_port = -1, i;
 
+	/*
+	 * Should we try to make guesses for multiport serial devices later?
+	 */
+	if ((dev->class >> 8) == PCI_CLASS_COMMUNICATION_MULTISERIAL)
+		return -ENODEV;
+
 	num_iomem = num_port = 0;
 	for (i = 0; i < PCI_NUM_BAR_RESOURCES; i++) {
 		if (pci_resource_flags(dev, i) & IORESOURCE_IO) {