custom baud rates for PL2303TA/TB

see https://lore.kernel.org/r/3aee5708-7961-f464-8c5f-6685d96920d6@IEEE.org

usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/DeviceTest.java

@@ -26,6 +26,7 @@ import com.hoho.android.usbserial.driver.Cp21xxSerialDriver;
 import com.hoho.android.usbserial.driver.FtdiSerialDriver;
 import com.hoho.android.usbserial.driver.ProbeTable;
 import com.hoho.android.usbserial.driver.ProlificSerialDriver;
+import com.hoho.android.usbserial.driver.ProlificWrapper;
 import com.hoho.android.usbserial.driver.SerialTimeoutException;
 import com.hoho.android.usbserial.driver.UsbId;
 import com.hoho.android.usbserial.driver.UsbSerialDriver;
@@ -323,11 +324,12 @@ public class DeviceTest {
         };
         usb.open();
 
+        int minBaudRate = ProlificWrapper.isDeviceTypeT(usb.serialPort) ? 6 : 46;
         try {
-            usb.setParameters(45, 8, 1, UsbSerialPort.PARITY_NONE);
+            usb.setParameters(minBaudRate-1, 8, 1, UsbSerialPort.PARITY_NONE);
             fail("baud rate to low expected");
         } catch(UnsupportedOperationException ignored) {}
-        usb.setParameters(46, 8, 1, UsbSerialPort.PARITY_NONE);
+        usb.setParameters(minBaudRate, 8, 1, UsbSerialPort.PARITY_NONE);
         usb.setParameters(384_000_000, 8, 1, UsbSerialPort.PARITY_NONE);
         try {
             usb.setParameters(384_000_001, 8, 1, UsbSerialPort.PARITY_NONE);

usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/driver/ProlificWrapper.java

@@ -0,0 +1,8 @@
+package com.hoho.android.usbserial.driver;
+
+public class ProlificWrapper {
+    public static boolean isDeviceTypeT(UsbSerialPort serialPort) {
+        ProlificSerialDriver.ProlificSerialPort prolificSerialPort = (ProlificSerialDriver.ProlificSerialPort) serialPort;
+        return prolificSerialPort.mDeviceType == ProlificSerialDriver.DeviceType.DEVICE_TYPE_T;
+    }
+}

usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/util/UsbWrapper.java

@@ -21,7 +21,6 @@ import java.util.Deque;
 import java.util.EnumSet;
 import java.util.LinkedList;
 import java.util.concurrent.Callable;
-import java.util.concurrent.Executors;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/ProlificSerialDriver.java

@@ -35,7 +35,7 @@ public class ProlificSerialDriver implements UsbSerialDriver {
             28800, 38400, 57600, 115200, 128000, 134400, 161280, 201600, 230400, 268800,
             403200, 460800, 614400, 806400, 921600, 1228800, 2457600, 3000000, 6000000
     };
-    private enum DeviceType { DEVICE_TYPE_01, DEVICE_TYPE_HX}
+    protected enum DeviceType { DEVICE_TYPE_01, DEVICE_TYPE_T, DEVICE_TYPE_HX}
 
     private final UsbDevice mDevice;
     private final UsbSerialPort mPort;
@@ -98,7 +98,7 @@ public class ProlificSerialDriver implements UsbSerialDriver {
         private static final int STATUS_BUFFER_SIZE = 10;
         private static final int STATUS_BYTE_IDX = 8;
 
-        private DeviceType mDeviceType = DeviceType.DEVICE_TYPE_HX;
+        protected DeviceType mDeviceType = DeviceType.DEVICE_TYPE_HX;
         private UsbEndpoint mInterruptEndpoint;
         private int mControlLinesValue = 0;
         private int mBaudRate = -1, mDataBits = -1, mStopBits = -1, mParity = -1;
@@ -163,7 +163,7 @@ public class ProlificSerialDriver implements UsbSerialDriver {
             vendorIn(0x8383, 0, 1);
             vendorOut(0, 1, null);
             vendorOut(1, 0, null);
-            vendorOut(2, (mDeviceType == DeviceType.DEVICE_TYPE_HX) ? 0x44 : 0x24, null);
+            vendorOut(2, (mDeviceType == DeviceType.DEVICE_TYPE_01) ? 0x24 : 0x44, null);
         }
 
         private void setControlLines(int newControlLinesValue) throws IOException {
@@ -253,26 +253,22 @@ public class ProlificSerialDriver implements UsbSerialDriver {
                 }
             }
 
-            if (mDevice.getDeviceClass() == 0x02) {
-                mDeviceType = DeviceType.DEVICE_TYPE_01;
-            } else {
             byte[] rawDescriptors = connection.getRawDescriptors();
-                if(rawDescriptors == null || rawDescriptors.length <8) {
+            if(rawDescriptors == null || rawDescriptors.length < 14) {
-                    Log.w(TAG, "Could not get device descriptors, Assuming that it is a HX device");
+                throw new IOException("Could not get device descriptors");
-                    mDeviceType = DeviceType.DEVICE_TYPE_HX;
+            }
-                } else {
+            int usbVersion = (rawDescriptors[3] << 8) + rawDescriptors[2];
+            int deviceVersion = (rawDescriptors[13] << 8) + rawDescriptors[12];
             byte maxPacketSize0 = rawDescriptors[7];
-                    if (maxPacketSize0 == 64) {
+            if (mDevice.getDeviceClass() == 0x02 || maxPacketSize0 != 64) {
-                        mDeviceType = DeviceType.DEVICE_TYPE_HX;
-                    } else if ((mDevice.getDeviceClass() == 0x00)
-                            || (mDevice.getDeviceClass() == 0xff)) {
                 mDeviceType = DeviceType.DEVICE_TYPE_01;
+            } else if(deviceVersion == 0x300 && usbVersion == 0x200) {
+                mDeviceType = DeviceType.DEVICE_TYPE_T; // TA
+            } else if(deviceVersion == 0x500) {
+                mDeviceType = DeviceType.DEVICE_TYPE_T; // TB
             } else {
-                        Log.w(TAG, "Could not detect PL2303 subtype, Assuming that it is a HX device");
                 mDeviceType = DeviceType.DEVICE_TYPE_HX;
             }
-                }
-            }
             setControlLines(mControlLinesValue);
             resetDevice();
             doBlackMagic();
@@ -315,21 +311,39 @@ public class ProlificSerialDriver implements UsbSerialDriver {
             }
             /*
              * Formula taken from Linux + FreeBSD.
+             *
+             * For TA+TB devices
+             *   baudrate = baseline / (mantissa * 2^exponent)
+             * where
+             *   mantissa = buf[10:0]
+             *   exponent = buf[15:13 16]
+             *
+             * For other devices
              *   baudrate = baseline / (mantissa * 4^exponent)
              * where
              *   mantissa = buf[8:0]
              *   exponent = buf[11:9]
              *
-             * Note: The formula does not work for all PL2303 variants.
-             *       Ok for PL2303HX. Not ok for PL2303TA. Other variants unknown.
              */
-            int baseline, mantissa, exponent;
+            int baseline, mantissa, exponent, buf, effectiveBaudRate;
             baseline = 12000000 * 32;
             mantissa = baseline / baudRate;
             if (mantissa == 0) { // > unrealistic 384 MBaud
                 throw new UnsupportedOperationException("Baud rate to high");
             }
             exponent = 0;
+            if (mDeviceType == DeviceType.DEVICE_TYPE_T) {
+                while (mantissa >= 2048) {
+                    if (exponent < 15) {
+                        mantissa >>= 1;    /* divide by 2 */
+                        exponent++;
+                    } else { // < 7 baud
+                        throw new UnsupportedOperationException("Baud rate to low");
+                    }
+                }
+                buf = mantissa + ((exponent & ~1) << 12) + ((exponent & 1) << 16) + (1 << 31);
+                effectiveBaudRate = (baseline / mantissa) >> exponent;
+            } else {
                 while (mantissa >= 512) {
                     if (exponent < 7) {
                         mantissa >>= 2;    /* divide by 4 */
@@ -338,11 +352,12 @@ public class ProlificSerialDriver implements UsbSerialDriver {
                         throw new UnsupportedOperationException("Baud rate to low");
                     }
                 }
-            int effectiveBaudRate = (baseline / mantissa) >> (exponent << 1);
+                buf = mantissa + (exponent << 9) + (1 << 31);
+                effectiveBaudRate = (baseline / mantissa) >> (exponent << 1);
+            }
             double baudRateError = Math.abs(1.0 - (effectiveBaudRate / (double)baudRate));
             if(baudRateError >= 0.031) // > unrealistic 11.6 Mbaud
                 throw new UnsupportedOperationException(String.format("Baud rate deviation %.1f%% is higher than allowed 3%%", baudRateError*100));
-            int buf = mantissa + (exponent<<9) + (1<<31);
 
             Log.d(TAG, String.format("baud rate=%d, effective=%d, error=%.1f%%, value=0x%08x, mantissa=%d, exponent=%d",
                     baudRate, effectiveBaudRate, baudRateError*100, buf, mantissa, exponent));