m-labs · Dec 2, 2014 · Dec 2, 2014
Showing with 35 additions and 15 deletions.

+26 −14 artiq/coredevice/comm_serial.py

+9 −1 soc/runtime/comm_serial.c
diff --git a/artiq/coredevice/comm_serial.py b/artiq/coredevice/comm_serial.py
@@ -22,6 +22,7 @@ class _H2DMsgType(Enum):
     REQUEST_IDENT = 1
     LOAD_OBJECT = 2
     RUN_KERNEL = 3
+    SET_BAUD_RATE = 4
 
 
 class _D2HMsgType(Enum):
@@ -58,6 +59,11 @@ class Comm:
     def __init__(self, dev="/dev/ttyUSB1", baud=115200):
         self._fd = os.open(dev, os.O_RDWR | os.O_NOCTTY)
         self.port = os.fdopen(self._fd, "r+b", buffering=0)
+        self.set_baud(115200)
+        self.set_remote_baud(baud)
+        self.set_baud(baud)
+
+    def set_baud(self, baud):
         iflag, oflag, cflag, lflag, ispeed, ospeed, cc = \
             termios.tcgetattr(self._fd)
         iflag = termios.IGNBRK | termios.IGNPAR
@@ -72,9 +78,27 @@ def __init__(self, dev="/dev/ttyUSB1", baud=115200):
         termios.tcdrain(self._fd)
         termios.tcflush(self._fd, termios.TCOFLUSH)
         termios.tcflush(self._fd, termios.TCIFLUSH)
-        logger.debug("connected to {} at {} baud".format(dev, baud))
+        logger.debug("baud rate set to".format(baud))
+
+    def set_remote_baud(self, baud):
+        _write_exactly(self.port, struct.pack(
+            ">lbl", 0x5a5a5a5a, _H2DMsgType.SET_BAUD_RATE.value, baud))
+        handshake = 0
+        while handshake < 4:
+            recv = struct.unpack(
+                "B", _read_exactly(self.port, 1))
+            if recv[0] == 0x5a:
+                handshake += 1
+            else:
+                # FIXME: when loading immediately after a board reset,
+                # we erroneously get some zeros back.
+                logger.warning("unexpected sync character: {:02x}".format(int(recv[0])))
+                handshake = 0
+        self.set_baud(baud)
+        logger.debug("synchronized")
 
     def close(self):
+        self.set_remote_baud(115200)
         self.port.close()
 
     def __enter__(self):
@@ -85,19 +109,7 @@ def __exit__(self, type, value, traceback):
 
     def _get_device_msg(self):
         while True:
-            # FIXME: when loading immediately after a board reset,
-            # we erroneously get some zeros back.
-            # Ignore them with a warning for now.
-            spurious_zero_count = 0
-            while True:
-                (reply, ) = struct.unpack("B", _read_exactly(self.port, 1))
-                if reply == 0:
-                    spurious_zero_count += 1
-                else:
-                    break
-            if spurious_zero_count:
-                logger.warning("received {} spurious zeros".format(
-                    spurious_zero_count))
+            (reply, ) = struct.unpack("B", _read_exactly(self.port, 1))
             msg = _D2HMsgType(reply)
             if msg == _D2HMsgType.LOG:
                 (length, ) = struct.unpack(">h", _read_exactly(self.port, 2))

diff --git a/soc/runtime/comm_serial.c b/soc/runtime/comm_serial.c
@@ -10,6 +10,7 @@ enum {
     MSGTYPE_REQUEST_IDENT = 1,
     MSGTYPE_LOAD_OBJECT,
     MSGTYPE_RUN_KERNEL,
+    MSGTYPE_SET_BAUD_RATE,
 };
 
 /* device to host */
@@ -161,7 +162,14 @@ void comm_serve(object_loader load_object, kernel_runner run_kernel)
             receive_and_load_object(load_object);
         else if(msgtype == MSGTYPE_RUN_KERNEL)
             receive_and_run_kernel(run_kernel);
-        else
+        else if(msgtype == MSGTYPE_SET_BAUD_RATE) {
+            unsigned int ftw;
+
+            ftw = ((long long)receive_int() << 32LL)/(long long)identifier_frequency_read();
+            send_int(0x5a5a5a5a);
+            uart_sync();
+            uart_tuning_word_write(ftw);
+        } else
             send_char(MSGTYPE_MESSAGE_UNRECOGNIZED);
     }
 }