fix #2 - Update on slave error response

Signed-off-by: Anderson Ignacio <[email protected]>

cocotbext/ahb/ahb_master.py

@@ -4,7 +4,7 @@
 # License           : MIT license <Check LICENSE>
 # Author            : Anderson I. da Silva (aignacio) <[email protected]>
 # Date              : 08.10.2023
-# Last Modified Date: 29.10.2023
+# Last Modified Date: 12.11.2023
 
 import cocotb
 import logging
@@ -146,9 +146,17 @@ async def _send_txn(
         response = []
         first_txn = True
 
-        for index, (txn_addr, txn_data, txn_size, txn_mode, txn_trans) in enumerate(
-            zip(address, value, size, mode, trans)
-        ):
+        index = 0
+        restart = False
+
+        while index < len(address):
+            txn_addr, txn_data, txn_size, txn_mode, txn_trans = (
+                address[index],
+                value[index],
+                size[index],
+                mode[index],
+                trans[index],
+            )
             if index == len(address) - 1:
                 self._init_bus()
             else:
@@ -168,26 +176,46 @@ async def _send_txn(
                 self.bus.hready_in.value = 1
 
             await RisingEdge(self.clk)
-            timeout_counter = 0
 
-            if self.bus.hready.value.is_resolvable is False:
-                while self.bus.hready.value.is_resolvable is False:
-                    timeout_counter += 1
-                    if timeout_counter == self.timeout:
-                        raise Exception(
-                            f"Timeout value of {timeout_counter}"
-                            f" clock cycles has been reached!"
-                        )
-                    await RisingEdge(self.clk)
-            else:
-                while self.bus.hready.value != 1:
-                    timeout_counter += 1
-                    if timeout_counter == self.timeout:
-                        raise Exception(
-                            f"Timeout value of {timeout_counter}"
-                            f" clock cycles has been reached!"
-                        )
-                    await RisingEdge(self.clk)
+            # First check if the slave signals are resolvable
+            timeout_counter = 0
+            while any(
+                [
+                    not self.bus.hready.value.is_resolvable,
+                    not self.bus.hresp.value.is_resolvable,
+                    not self.bus.hrdata.value.is_resolvable,
+                ]
+            ):
+                timeout_counter += 1
+                if timeout_counter == self.timeout:
+                    raise Exception(
+                        f"Timeout value of {timeout_counter}"
+                        f" clock cycles has been reached because AHB.SLAVE"
+                        f"signals are not resolvable!\n"
+                        f"hready: {self.bus.hready.value.is_resolvable}\n"
+                        f"hrdata: {self.bus.hrdata.value.is_resolvable}\n"
+                        f"hresp: {self.bus.hresp.value.is_resolvable}\n"
+                    )
+                await RisingEdge(self.clk)
+
+            index += 1
+            # Wait till a response is available from the slave
+            while self.bus.hready.value != 1:
+                if self.bus.hresp == AHBResp.ERROR:
+                    if self.bus.htrans.value.is_resolvable:
+                        if self.bus.htrans.value == AHBTrans.NONSEQ:
+                            index -= 1  # Redo the txn
+                            self.bus.htrans.value = (
+                                AHBTrans.IDLE
+                            )  # Withdrawn the req. in case of error
+                            restart = True
+                timeout_counter += 1
+                if timeout_counter == self.timeout:
+                    raise Exception(
+                        f"Timeout value of {timeout_counter}"
+                        f" clock cycles has been reached!"
+                    )
+                await RisingEdge(self.clk)
 
             if first_txn:
                 first_txn = False
@@ -202,6 +230,10 @@ async def _send_txn(
                         "data": hex(self.bus.hrdata.value),
                     }
                 ]
+            if restart:  # As we withdrawn the last txn, let's restart
+                first_txn = True
+                restart = False
+
         self._init_bus()
         return response
 

cocotbext/ahb/ahb_monitor.py

@@ -165,6 +165,9 @@ def _check_signals(self, stable):
             if current[signal].value.is_resolvable is not True:
                 raise AssertionError(f"Signal master.{signal} is not resolvable!")
             if current[signal].value != stable[signal]:
-                raise AssertionError(
-                    f"AHB PROTOCOL VIOLATION: Master.{signal} signal should not change before slave.hready == 1"
-                )
+                if (signal == "htrans") and (self.bus.hresp.value == AHBResp.ERROR):
+                    pass
+                else:
+                    raise AssertionError(
+                        f"AHB PROTOCOL VIOLATION: Master.{signal} signal should not change before slave.hready == 1"
+                    )

cocotbext/ahb/ahb_slave.py

@@ -4,7 +4,7 @@
 # License           : MIT license <Check LICENSE>
 # Author            : Anderson I. da Silva (aignacio) <[email protected]>
 # Date              : 16.10.2023
-# Last Modified Date: 27.10.2023
+# Last Modified Date: 12.11.2023
 
 import cocotb
 import logging
@@ -80,6 +80,7 @@ async def _proc_txn(self):
             await RisingEdge(self.clk)
 
             cur_hready = copy.deepcopy(self.bus.hready.value)
+            cur_hresp = copy.deepcopy(self.bus.hresp.value)
 
             # Default values in case there is no txn
             self.bus.hready.value = self._get_def(1)
@@ -93,7 +94,12 @@ async def _proc_txn(self):
             if ready:
                 self.bus.hready.value = 1
 
-            if error:
+            if error and (cur_hresp == AHBResp.OKAY):  # First cycle of error response
+                self.bus.hready.value = 0
+                self.bus.hresp.value = AHBResp.ERROR
+            elif error and (
+                cur_hresp == AHBResp.ERROR
+            ):  # Second cycle of error response
                 self.bus.hready.value = 1
                 self.bus.hresp.value = AHBResp.ERROR
                 error = False
@@ -110,7 +116,12 @@ async def _proc_txn(self):
                         self.bus.hresp.value = AHBResp.OKAY
 
             # Check for new txn
-            if cur_hready == 1 and self._check_inputs() and self._check_valid_txn():
+            if (
+                (cur_hready == 1)
+                and (cur_hresp != AHBResp.ERROR)
+                and self._check_inputs()
+                and self._check_valid_txn()
+            ):
                 txn_addr = self.bus.haddr.value
                 txn_size = AHBSize(self.bus.hsize.value)
                 txn_type = AHBWrite(self.bus.hwrite.value)

cocotbext/ahb/version.py

@@ -1 +1 @@
-__version__ = "0.1.6"
+__version__ = "0.1.7"