cpu: Make automatic transition to OFF optional

Add the power_gating_on_idle option to control whether a core
automatically enters the power gated state. The default behaviour is
to transition to clock gated when idle, but not to power gated. When
this option is set to true, the core automatically transitions to the
power gated state after a configurable latency.

Change-Id: Ida98c7fc532de4140d0e511c25613769b47b3702
Reviewed-on: https://gem5-review.googlesource.com/5741
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/src/cpu/base.hh b/src/cpu/base.hh
index 7039fcfbc..13c56a945 100644
--- a/src/cpu/base.hh
+++ b/src/cpu/base.hh
@@ -588,10 +588,13 @@ class BaseCPU : public MemObject
     bool waitForRemoteGDB() const;
 
     Cycles syscallRetryLatency;
+
   // Enables CPU to enter power gating on a configurable cycle count
   protected:
-    const Cycles pwrGatingLatency;
     void enterPwrGating();
+
+    const Cycles pwrGatingLatency;
+    const bool powerGatingOnIdle;
     EventFunctionWrapper enterPwrGatingEvent;
 };