mem: Make DRAMCtrl::decodeAddr const

DRAMCtrl's decodeAddr does not need to modify the packet it
receives, nor should it modify the contents of the class,
and therefore both the packet and the function are made const.

Change-Id: I577f48d9a43611ba54878a9a793cb7b4fbb326f4
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17540
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>

src/mem/dram_ctrl.cc

@@ -303,8 +303,8 @@ DRAMCtrl::writeQueueFull(unsigned int neededEntries) const
 }
 
 DRAMCtrl::DRAMPacket*
-DRAMCtrl::decodeAddr(PacketPtr pkt, Addr dramPktAddr, unsigned size,
-                       bool isRead)
+DRAMCtrl::decodeAddr(const PacketPtr pkt, Addr dramPktAddr, unsigned size,
+                     bool isRead) const
 {
     // decode the address based on the address mapping scheme, with
     // Ro, Ra, Co, Ba and Ch denoting row, rank, column, bank and

src/mem/dram_ctrl.hh

@@ -839,8 +839,8 @@ class DRAMCtrl : public QoS::MemCtrl
      * @param isRead Is the request for a read or a write to DRAM
      * @return A DRAMPacket pointer with the decoded information
      */
-    DRAMPacket* decodeAddr(PacketPtr pkt, Addr dramPktAddr, unsigned int size,
-                           bool isRead);
+    DRAMPacket* decodeAddr(const PacketPtr pkt, Addr dramPktAddr,
+                           unsigned int size, bool isRead) const;
 
     /**
      * The memory schduler/arbiter - picks which request needs to