configs, mem: MemInterface generating its own controller

We are adding a controller method to MemInterface objects making
them able to generate the appropriate memory controller.

This will bring the following benefits

a) Semplification: It will simplify MemConfig.config_mem
b) Reusability: Scripts not using config_mem
won't have to duplicate the if...else checks
c) Modularity: Users will be able to define their own
dram interfaces without needing to handle the mem_ctrl
mapping in the shared MemConfig.py module

Change-Id: I4b836fd7c91675cf7aacc644f25989484d5be3ec
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/42074
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Wendy Elsasser <wendy.elsasser@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

configs/common/MemConfig.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2013, 2017, 2020 ARM Limited
+# Copyright (c) 2013, 2017, 2020-2021 Arm Limited
 # All rights reserved.
 #
 # The license below extends only to copyright in the software and shall
@@ -218,24 +218,7 @@ def config_mem(options, system):
                         "latency to 1ns.")
 
                 # Create the controller that will drive the interface
-                if opt_mem_type == "HMC_2500_1x32":
-                    # The static latency of the vault controllers is estimated
-                    # to be smaller than a full DRAM channel controller
-                    mem_ctrl = m5.objects.MemCtrl(min_writes_per_switch = 8,
-                                             static_backend_latency = '4ns',
-                                             static_frontend_latency = '4ns')
-                elif opt_mem_type == "SimpleMemory":
-                    mem_ctrl = m5.objects.SimpleMemory()
-                elif opt_mem_type == "QoSMemSinkInterface":
-                    mem_ctrl = m5.objects.QoSMemSinkCtrl()
-                else:
-                    mem_ctrl = m5.objects.MemCtrl()
-
-                # Hookup the controller to the interface and add to the list
-                if opt_mem_type == "QoSMemSinkInterface":
-                    mem_ctrl.interface = dram_intf
-                elif opt_mem_type != "SimpleMemory":
-                    mem_ctrl.dram = dram_intf
+                mem_ctrl = dram_intf.controller()
 
                 mem_ctrls.append(mem_ctrl)
 

src/mem/DRAMInterface.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2012-2020 ARM Limited
+# Copyright (c) 2012-2021 Arm Limited
 # All rights reserved.
 #
 # The license below extends only to copyright in the software and shall
@@ -38,6 +38,7 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+from m5.objects.MemCtrl import MemCtrl
 from m5.objects.MemInterface import *
 
 # Enum for the page policy, either open, open_adaptive, close, or
@@ -254,6 +255,15 @@ class DRAMInterface(MemInterface):
     # Second voltage range defined by some DRAMs
     VDD2 = Param.Voltage("0V", "2nd Voltage Range")
 
+    def controller(self):
+        """
+        Instantiate the memory controller and bind it to
+        the current interface.
+        """
+        controller = MemCtrl()
+        controller.dram = self
+        return controller
+
 # A single DDR3-1600 x64 channel (one command and address bus), with
 # timings based on a DDR3-1600 4 Gbit datasheet (Micron MT41J512M8) in
 # an 8x8 configuration.
@@ -424,6 +434,17 @@ class HMC_2500_1x32(DDR3_1600_8x8):
     write_buffer_size = 32
     read_buffer_size = 32
 
+    def controller(self):
+        """
+        Instantiate the memory controller and bind it to
+        the current interface.
+        """
+        controller = MemCtrl(min_writes_per_switch = 8,
+            static_backend_latency = '4ns',
+            static_frontend_latency = '4ns')
+        controller.dram = self
+        return controller
+
 # A single DDR3-2133 x64 channel refining a selected subset of the
 # options for the DDR-1600 configuration, based on the same DDR3-1600
 # 4 Gbit datasheet (Micron MT41J512M8). Most parameters are kept

src/mem/SimpleMemory.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2012-2013 ARM Limited
+# Copyright (c) 2012-2013, 2021 Arm Limited
 # All rights reserved.
 #
 # The license below extends only to copyright in the software and shall
@@ -49,3 +49,7 @@ class SimpleMemory(AbstractMemory):
     # representative of a x64 DDR3-1600 channel.
     bandwidth = Param.MemoryBandwidth('12.8GiB/s',
                                       "Combined read and write bandwidth")
+
+    def controller(self):
+        # Simple memory doesn't use a MemCtrl
+        return self

src/mem/qos/QoSMemSinkInterface.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2020 ARM Limited
+# Copyright (c) 2020-2021 Arm Limited
 # All rights reserved.
 #
 # The license below extends only to copyright in the software and shall
@@ -38,3 +38,12 @@ from m5.objects.AbstractMemory import AbstractMemory
 class QoSMemSinkInterface(AbstractMemory):
     type = 'QoSMemSinkInterface'
     cxx_header = "mem/qos/mem_sink.hh"
+
+    def controller(self):
+        """
+        Instantiate the memory controller and bind it to
+        the current interface.
+        """
+        controller = QoSMemSinkCtrl()
+        controller.interface = self
+        return controller