Correctly determine Microchip pid:vid 04d8:000a device class

According to the Linux kernel tree [1], Microchip pid:vid 04d8:000a
is generally a CDC ACM device, implemented by a demo firmware
application.

However, some vendors have re-used this vid:pid for other types of
firmware, emulating FTDI chips. The Linux kernel attempts to detect
such cases by matching on interface class/subclass/proto. If these
are ff/ff/00 it uses FTDI, otherwise CDC.

Mimic the Linux kernel's logic in determining whether the Microchip
device is CDC or FTDI.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f08dea734844aa42ec57c229b0b73b3d7d21f810

usbserial/src/main/java/com/felhr/deviceids/FTDISioIds.java

@@ -1,5 +1,8 @@
 package com.felhr.deviceids;
 
+import android.hardware.usb.UsbDevice;
+import android.hardware.usb.UsbInterface;
+
 import static com.felhr.deviceids.Helpers.createTable;
 import static com.felhr.deviceids.Helpers.createDevice;
 
@@ -251,7 +254,6 @@ private FTDISioIds()
             createDevice(0x03eb, 0x2109),
             createDevice(0x0456, 0xf000),
             createDevice(0x0456, 0xf001),
-            createDevice(0x04d8, 0x000a),
             createDevice(0x0584, 0xb020),
             createDevice(0x0647, 0x0100),
             createDevice(0x06CE, 0x8311),
@@ -560,7 +562,25 @@ private FTDISioIds()
             createDevice(0x0403, 0x0) //fake FTDI reprogrammed by driver
     );
 
-    public static boolean isDeviceSupported(int vendorId, int productId) {
+    private static boolean isMicrochipFtdi(UsbDevice dev) {
+        if (dev.getVendorId() != 0x04d8 || dev.getProductId() != 0x000a)
+            return false;
+        for (int i = 0; i < dev.getInterfaceCount(); i++) {
+            UsbInterface intf = dev.getInterface(i);
+            if (intf.getInterfaceClass() == 0xff && intf.getInterfaceSubclass() == 0xff &&
+                    intf.getInterfaceProtocol() == 0x00)
+                return true;
+        }
+        return false;
+    }
+
+    public static boolean isDeviceSupported(UsbDevice dev) {
+        return Helpers.exists(ftdiDevices, dev.getVendorId(), dev.getProductId()) ||
+                isMicrochipFtdi(dev);
+
+    }
+
+    static boolean isDeviceIdSupported(int vendorId, int productId) {
         return Helpers.exists(ftdiDevices, vendorId, productId);
     }
 }

usbserial/src/main/java/com/felhr/usbserial/UsbSerialDevice.java

@@ -72,7 +72,7 @@ public static UsbSerialDevice createUsbSerialDevice(UsbDevice device, UsbDeviceC
         int vid = device.getVendorId();
         int pid = device.getProductId();
 
-        if(FTDISioIds.isDeviceSupported(vid, pid))
+        if(FTDISioIds.isDeviceSupported(device))
             return new FTDISerialDevice(device, connection, iface);
         else if(CP210xIds.isDeviceSupported(vid, pid))
             return new CP2102SerialDevice(device, connection, iface);
@@ -107,7 +107,7 @@ public static boolean isSupported(UsbDevice device)
         int vid = device.getVendorId();
         int pid = device.getProductId();
 
-        if(FTDISioIds.isDeviceSupported(vid, pid))
+        if(FTDISioIds.isDeviceSupported(device))
             return true;
         else if(CP210xIds.isDeviceSupported(vid, pid))
             return true;

usbserial/src/test/java/com/felhr/deviceids/DeviceIdTest.java

@@ -48,7 +48,7 @@ public void testLongPacking() {
 
         for (TestCase tc : cases) {
             Assert.assertTrue(CP210xIds.isDeviceSupported(tc.vendor, tc.product));
-            Assert.assertFalse(FTDISioIds.isDeviceSupported(tc.vendor, tc.product));
+            Assert.assertFalse(FTDISioIds.isDeviceIdSupported(tc.vendor, tc.product));
         }
     }