systemc: Implement sc_mutex.

Change-Id: I8a5bd03b46d44aeca3bba15a01a5f2180b4ed5c7
Reviewed-on: https://gem5-review.googlesource.com/c/12618
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

src/systemc/channel/sc_mutex.cc

@@ -28,6 +28,7 @@
  */
 
 #include "base/logging.hh"
+#include "systemc/core/scheduler.hh"
 #include "systemc/ext/channel/sc_mutex.hh"
 #include "systemc/ext/core/sc_module.hh" // for sc_gen_unique_name
 
@@ -45,24 +46,29 @@ sc_mutex::sc_mutex(const char *name) :
 int
 sc_mutex::lock()
 {
-    warn("%s not implemented.\n", __PRETTY_FUNCTION__);
+    while (trylock() == -1)
+        wait(unlockEvent);
     return 0;
 }
 
 int
 sc_mutex::trylock()
 {
-    warn("%s not implemented.\n", __PRETTY_FUNCTION__);
+    if (holder.valid())
+        return -1;
+    holder = ::sc_gem5::scheduler.current();
     return 0;
 }
 
 int
 sc_mutex::unlock()
 {
-    warn("%s not implemented.\n", __PRETTY_FUNCTION__);
+    if (holder != ::sc_gem5::scheduler.current())
+        return -1;
+
+    holder = nullptr;
+    unlockEvent.notify();
     return 0;
 }
 
-const char *sc_mutex::kind() const { return "sc_mutex"; }
-
 } // namespace sc_core

src/systemc/ext/channel/sc_mutex.hh

@@ -30,7 +30,9 @@
 #ifndef __SYSTEMC_EXT_CHANNEL_SC_MUTEX_HH__
 #define __SYSTEMC_EXT_CHANNEL_SC_MUTEX_HH__
 
+#include "../core/sc_event.hh"
 #include "../core/sc_object.hh"
+#include "../core/sc_process_handle.hh"
 #include "sc_mutex_if.hh"
 
 namespace sc_core
@@ -46,12 +48,15 @@ class sc_mutex : public sc_mutex_if, public sc_object
     virtual int trylock();
     virtual int unlock();
 
-    virtual const char *kind() const;
+    virtual const char *kind() const { return "sc_mutex"; }
 
   private:
     // Disabled
     sc_mutex(const sc_mutex &) : sc_interface(), sc_mutex_if(), sc_object() {}
     sc_mutex &operator = (const sc_mutex &) { return *this; }
+
+    sc_process_handle holder;
+    sc_event unlockEvent;
 };
 
 } // namespace sc_core