mem: add DRAM powerdown timing

src/mem/DRAMCtrl.py

@@ -370,6 +370,12 @@ class DDR3_1600_x64(DRAMCtrl):
     # <=85C, half for >85C
     tREFI = '7.8us'
 
+    # active powerdown and precharge powerdown exit time
+    tXP = '6ns'
+
+    # self refresh exit time
+    tXS = '270ns'
+
     # Current values from datasheet
     IDD0 = '75mA'
     IDD2N = '50mA'
@@ -591,6 +597,12 @@ class DDR4_2400_x64(DRAMCtrl):
     # <=85C, half for >85C
     tREFI = '7.8us'
 
+    # active powerdown and precharge powerdown exit time
+    tXP = '6ns'
+
+    # self refresh exit time
+    tXS = '120ns'
+
     # Current values from datasheet
     IDD0 = '70mA'
     IDD02 = '4.6mA'
@@ -659,6 +671,12 @@ class LPDDR2_S4_1066_x32(DRAMCtrl):
     tRFC = '130ns'
     tREFI = '3.9us'
 
+    # active powerdown and precharge powerdown exit time
+    tXP = '7.5ns'
+
+    # self refresh exit time
+    tXS = '140ns'
+
     # Irrespective of speed grade, tWTR is 7.5 ns
     tWTR = '7.5ns'
 
@@ -815,6 +833,12 @@ class LPDDR3_1600_x32(DRAMCtrl):
     tRFC = '130ns'
     tREFI = '3.9us'
 
+    # active powerdown and precharge powerdown exit time
+    tXP = '7.5ns'
+
+    # self refresh exit time
+    tXS = '140ns'
+
     # Irrespective of speed grade, tWTR is 7.5 ns
     tWTR = '7.5ns'
 
@@ -1057,3 +1081,9 @@ class HBM_1000_4H_x64(HBM_1000_4H_x128):
     # Default different rank bus delay to 2 CK, @1000 MHz = 2 ns
     tCS = '2ns'
     tREFI = '3.9us'
+
+    # active powerdown and precharge powerdown exit time
+    tXP = '10ns'
+
+    # self refresh exit time
+    tXS = '65ns'

src/mem/dram_ctrl.cc

@@ -82,7 +82,8 @@ DRAMCtrl::DRAMCtrl(const DRAMCtrlParams* p) :
     tCK(p->tCK), tWTR(p->tWTR), tRTW(p->tRTW), tCS(p->tCS), tBURST(p->tBURST),
     tCCD_L(p->tCCD_L), tRCD(p->tRCD), tCL(p->tCL), tRP(p->tRP), tRAS(p->tRAS),
     tWR(p->tWR), tRTP(p->tRTP), tRFC(p->tRFC), tREFI(p->tREFI), tRRD(p->tRRD),
-    tRRD_L(p->tRRD_L), tXAW(p->tXAW), activationLimit(p->activation_limit),
+    tRRD_L(p->tRRD_L), tXAW(p->tXAW), tXP(p->tXP), tXS(p->tXS),
+    activationLimit(p->activation_limit),
     memSchedPolicy(p->mem_sched_policy), addrMapping(p->addr_mapping),
     pageMgmt(p->page_policy),
     maxAccessesPerRow(p->max_accesses_per_row),

src/mem/dram_ctrl.hh

@@ -726,6 +726,8 @@ class DRAMCtrl : public AbstractMemory
     const Tick tRRD;
     const Tick tRRD_L;
     const Tick tXAW;
+    const Tick tXP;
+    const Tick tXS;
     const uint32_t activationLimit;
 
     /**