m-labs · Mar 8, 2016 · Mar 9, 2016 · Mar 9, 2016 · Mar 9, 2016 · Mar 9, 2016
diff --git a/artiq/coredevice/__init__.py b/artiq/coredevice/__init__.py
@@ -1,12 +1,12 @@
 from artiq.coredevice import exceptions, dds, spi
 from artiq.coredevice.exceptions import (RTIOUnderflow, RTIOSequenceError,
-                                         RTIOCollision, RTIOOverflow,
+                                         RTIOCollision, RTIOOverflow, RTIOBusy,
                                          DDSBatchError, CacheError)
 from artiq.coredevice.dds import (PHASE_MODE_CONTINUOUS, PHASE_MODE_ABSOLUTE,
                                   PHASE_MODE_TRACKING)
 
 __all__ = []
 __all__ += ["RTIOUnderflow", "RTIOSequenceError", "RTIOCollision",
-            "RTIOOverflow", "DDSBatchError", "CacheError"]
+            "RTIOOverflow", "RTIOBusy", "DDSBatchError", "CacheError"]
 __all__ += ["PHASE_MODE_CONTINUOUS", "PHASE_MODE_ABSOLUTE",
             "PHASE_MODE_TRACKING"]
diff --git a/artiq/coredevice/exceptions.py b/artiq/coredevice/exceptions.py
@@ -98,6 +98,18 @@ class RTIOCollision(Exception):
     """
     artiq_builtin = True
 
+class RTIOBusy(Exception):
+    """Raised when at least one output event could not be executed because
+    the given channel was already busy executing a previous event.
+
+    This exception is raised late: after the error condition occurred. More
+    specifically it is raised on submitting an event on the same channel after
+    the execution of the faulty event was attempted.
+
+    The offending event was discarded.
+    """
+    artiq_builtin = True
+
 class RTIOOverflow(Exception):
     """Raised when at least one event could not be registered into the RTIO
     input FIFO because it was full (CPU not reading fast enough).

diff --git a/artiq/coredevice/spi.py b/artiq/coredevice/spi.py
@@ -1,5 +1,5 @@
 from artiq.language.core import (kernel, portable, seconds_to_mu, now_mu,
-                                 delay_mu, int)
+                                 delay_mu, int, mu_to_seconds)
 from artiq.language.units import MHz
 from artiq.coredevice.rtio import rtio_output, rtio_input_data
 
@@ -58,7 +58,7 @@ def __init__(self, dmgr, channel, core_device="core"):
 
     @portable
     def frequency_to_div(self, f):
-        return int(1/(f*self.ref_period)) + 1
+        return int(1/(f*mu_to_seconds(self.ref_period_mu))) + 1
 
     @kernel
     def set_config(self, flags=0, write_freq=20*MHz, read_freq=20*MHz):

diff --git a/artiq/gateware/rtio/core.py b/artiq/gateware/rtio/core.py
@@ -54,6 +54,26 @@ def __init__(self, width):
         self.comb += gt.i.eq(self.value_rtio), self.value_sys.eq(gt.o)
 
 
+class _BlindTransfer(Module):
+    def __init__(self):
+        self.i = Signal()
+        self.o = Signal()
+
+        ps = PulseSynchronizer("rio", "rsys")
+        ps_ack = PulseSynchronizer("rsys", "rio")
+        self.submodules += ps, ps_ack
+        blind = Signal()
+        self.sync.rio += [
+            If(self.i, blind.eq(1)),
+            If(ps_ack.o, blind.eq(0))
+        ]
+        self.comb += [
+            ps.i.eq(self.i & ~blind),
+            ps_ack.i.eq(ps.o),
+            self.o.eq(ps.o)
+        ]
+
+
 # CHOOSING A GUARD TIME
 #
 # The buffer must be transferred to the FIFO soon enough to account for:
@@ -104,6 +124,7 @@ def __init__(self, interface, counter, fifo_depth, guard_io_cycles):
         self.underflow = Signal()  # valid 1 cycle after we, pulsed
         self.sequence_error = Signal()
         self.collision = Signal()
+        self.busy = Signal()  # pulsed
 
         # # #
 
@@ -220,12 +241,19 @@ def __init__(self, interface, counter, fifo_depth, guard_io_cycles):
         self.comb += fifo.re.eq(fifo.readable & (~dout_stb | dout_ack))
 
         # FIFO read through buffer
-        # TODO: report error on stb & busy
         self.comb += [
             dout_ack.eq(
                 dout.timestamp[fine_ts_width:] == counter.value_rtio),
             interface.stb.eq(dout_stb & dout_ack)
         ]
+
+        busy_transfer = _BlindTransfer()
+        self.submodules += busy_transfer
+        self.comb += [
+            busy_transfer.i.eq(interface.stb & interface.busy),
+            self.busy.eq(busy_transfer.o),
+        ]
+
         if data_width:
             self.comb += interface.data.eq(dout.data)
         if address_width:
@@ -248,7 +276,7 @@ def __init__(self, interface, counter, fifo_depth):
 
         self.readable = Signal()
         self.re = Signal()
-        
+
         self.overflow = Signal()  # pulsed
 
         # # #
@@ -281,18 +309,11 @@ def __init__(self, interface, counter, fifo_depth):
             fifo.re.eq(self.re)
         ]
 
-        overflow_sync = PulseSynchronizer("rio", "rsys")
-        overflow_ack_sync = PulseSynchronizer("rsys", "rio")
-        self.submodules += overflow_sync, overflow_ack_sync
-        overflow_blind = Signal()
-        self.comb += overflow_sync.i.eq(fifo.we & ~fifo.writable & ~overflow_blind)
-        self.sync.rio += [
-            If(fifo.we & ~fifo.writable, overflow_blind.eq(1)),
-            If(overflow_ack_sync.o, overflow_blind.eq(0))
-        ]
+        overflow_transfer = _BlindTransfer()
+        self.submodules += overflow_transfer
         self.comb += [
-            overflow_ack_sync.i.eq(overflow_sync.o),
-            self.overflow.eq(overflow_sync.o)
+            overflow_transfer.i.eq(fifo.we & ~fifo.writable),
+            self.overflow.eq(overflow_transfer.o),
         ]
 
 
@@ -339,10 +360,11 @@ def __init__(self, chan_sel_width,
             self.o_address = CSRStorage(address_width)
         self.o_timestamp = CSRStorage(full_ts_width)
         self.o_we = CSR()
-        self.o_status = CSRStatus(4)
+        self.o_status = CSRStatus(5)
         self.o_underflow_reset = CSR()
         self.o_sequence_error_reset = CSR()
         self.o_collision_reset = CSR()
+        self.o_busy_reset = CSR()
 
         if data_width:
             self.i_data = CSRStatus(data_width)
@@ -430,21 +452,26 @@ def __init__(self, channels, full_ts_width=63, guard_io_cycles=20):
             underflow = Signal()
             sequence_error = Signal()
             collision = Signal()
+            busy = Signal()
             self.sync.rsys += [
                 If(selected & self.kcsrs.o_underflow_reset.re,
                    underflow.eq(0)),
                 If(selected & self.kcsrs.o_sequence_error_reset.re,
                    sequence_error.eq(0)),
                 If(selected & self.kcsrs.o_collision_reset.re,
                    collision.eq(0)),
+                If(selected & self.kcsrs.o_busy_reset.re,
+                   busy.eq(0)),
                 If(o_manager.underflow, underflow.eq(1)),
                 If(o_manager.sequence_error, sequence_error.eq(1)),
-                If(o_manager.collision, collision.eq(1))
+                If(o_manager.collision, collision.eq(1)),
+                If(o_manager.busy, busy.eq(1))
             ]
             o_statuses.append(Cat(~o_manager.writable,
                                   underflow,
                                   sequence_error,
-                                  collision))
+                                  collision,
+                                  busy))
 
             if channel.interface.i is not None:
                 i_manager = _InputManager(channel.interface.i, self.counter,

diff --git a/artiq/runtime/rtio.c b/artiq/runtime/rtio.c
@@ -39,6 +39,12 @@ static void rtio_process_exceptional_status(
             "RTIO collision at {0} mu, channel {1}",
             timestamp, channel, 0);
     }
+    if(status & RTIO_O_STATUS_BUSY) {
+        rtio_o_busy_reset_write(1);
+        artiq_raise_from_c("RTIOBusy",
+            "RTIO busy on channel {0}",
+            channel, 0, 0);
+    }
 }
 
 

diff --git a/artiq/runtime/rtio.h b/artiq/runtime/rtio.h
@@ -7,6 +7,7 @@
 #define RTIO_O_STATUS_UNDERFLOW 2
 #define RTIO_O_STATUS_SEQUENCE_ERROR 4
 #define RTIO_O_STATUS_COLLISION 8
+#define RTIO_O_STATUS_BUSY 16
 #define RTIO_I_STATUS_EMPTY 1
 #define RTIO_I_STATUS_OVERFLOW 2
 

diff --git a/artiq/test/coredevice/test_spi.py b/artiq/test/coredevice/test_spi.py
@@ -0,0 +1,45 @@
+from artiq.experiment import *
+from artiq.test.hardware_testbench import ExperimentCase
+
+
+class Collision(EnvExperiment):
+    def build(self):
+        self.setattr_device("core")
+        self.setattr_device("spi0")
+
+    @kernel
+    def run(self):
+        self.core.break_realtime()
+        t = now_mu()
+        self.spi0.set_config_mu()
+        at_mu(t)
+        self.spi0.set_config_mu()
+
+
+class Busy(EnvExperiment):
+    def build(self):
+        self.setattr_device("core")
+        self.setattr_device("spi0")
+        self.setattr_device("led")
+
+    @kernel
+    def run(self):
+        self.core.break_realtime()
+        t = now_mu()
+        self.spi0.set_config_mu()
+        at_mu(t + self.spi0.ref_period_mu)
+        self.spi0.set_config_mu()  # causes the error
+        self.led.on()
+        self.led.sync()            # registers the error
+        self.core.break_realtime()
+        self.spi0.set_config_mu()  # raises the error
+
+
+class SPITest(ExperimentCase):
+    def test_collision(self):
+        with self.assertRaises(RTIOCollision):
+            self.execute(Collision)
+
+    def test_busy(self):
+        with self.assertRaises(RTIOBusy):
+            self.execute(Busy)
diff --git a/artiq/test/hardware_testbench.py b/artiq/test/hardware_testbench.py
@@ -109,7 +109,7 @@ def create(self, cls, **kwargs):
             # skip if ddb does not match requirements
             raise unittest.SkipTest(*e.args)
 
-    def execute(self, cls, *args, **kwargs):
+    def execute(self, cls, **kwargs):
         expid = {
             "file": sys.modules[cls.__module__].__file__,
             "class_name": cls.__name__,
@@ -124,3 +124,8 @@ def execute(self, cls, *args, **kwargs):
         except CompileError as error:
             # Reduce amount of text on terminal.
             raise error from None
+        except Exception as exn:
+            if hasattr(exn, "artiq_core_exception"):
+                exn.args = "{}\n{}".format(exn.args[0],
+                                           exn.artiq_core_exception),
+            raise exn