Add a dhrystone benchmark command

Drystone provides a convenient sanity check that the CPU is running at full
speed. Add this as a command which can be enabled as needed.

Note: I investigated using Coremark for this but there was a license
agreement and I could not work out if it was GPL-compatible.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/lib/dhry/dhry_2.c b/lib/dhry/dhry_2.c
new file mode 100644
index 0000000..59aa458
--- /dev/null
+++ b/lib/dhry/dhry_2.c
@@ -0,0 +1,217 @@
+/*
+ * (C) Copyright 2015 Google, Inc
+ *
+ * SPDX-License-Identifier:     GPL-2.0+
+ *
+ * Dhrystone is widely available in the public domain. A GPL license is
+ * chosen for U-Boot.
+ */
+
+/*****************************************************************************
+ *  The BYTE UNIX Benchmarks - Release 3
+ *          Module: dhry_2.c   SID: 3.4 5/15/91 19:30:22
+ *          
+ *****************************************************************************
+ * Bug reports, patches, comments, suggestions should be sent to:
+ *
+ *	Ben Smith, Rick Grehan or Tom Yager
+ *	ben@bytepb.byte.com   rick_g@bytepb.byte.com   tyager@bytepb.byte.com
+ *
+ *****************************************************************************
+ *  Modification Log:
+ *  10/22/97 - code cleanup to remove ANSI C compiler warnings
+ *             Andy Kahn <kahn@zk3.dec.com>
+ *
+ *  Adapted from:
+ *
+ *                   "DHRYSTONE" Benchmark Program
+ *                   -----------------------------
+ *
+ * **** WARNING **** See warning in n.dhry_1.c
+ *                                                                            
+ *  Version:    C, Version 2.1
+ *                                                                            
+ *  File:       dhry_2.c (part 3 of 3)
+ *
+ *  Date:       May 25, 1988
+ *
+ *  Author:     Reinhold P. Weicker
+ *
+ ****************************************************************************/
+/* SCCSid is defined in dhry_1.c */
+
+#include <common.h>
+#include "dhry.h"
+
+#ifndef REG
+#define REG
+        /* REG becomes defined as empty */
+        /* i.e. no register variables   */
+#endif
+
+extern  int     Int_Glob;
+extern  char    Ch_1_Glob;
+
+void Proc_6(Enumeration, Enumeration *);
+void Proc_7(One_Fifty, One_Fifty, One_Fifty *);
+void Proc_8(Arr_1_Dim, Arr_2_Dim, int, int);
+Enumeration Func_1(Capital_Letter, Capital_Letter);
+Boolean Func_2(Str_30, Str_30);
+Boolean Func_3(Enumeration);
+
+void Proc_6 (Enumeration Enum_Val_Par, Enumeration *Enum_Ref_Par)
+    /* executed once */
+    /* Enum_Val_Par == Ident_3, Enum_Ref_Par becomes Ident_2 */
+{
+  *Enum_Ref_Par = Enum_Val_Par;
+  if (! Func_3 (Enum_Val_Par))
+    /* then, not executed */
+    *Enum_Ref_Par = Ident_4;
+  switch (Enum_Val_Par)
+  {
+    case Ident_1: 
+      *Enum_Ref_Par = Ident_1;
+      break;
+    case Ident_2: 
+      if (Int_Glob > 100)
+        /* then */
+      *Enum_Ref_Par = Ident_1;
+      else *Enum_Ref_Par = Ident_4;
+      break;
+    case Ident_3: /* executed */
+      *Enum_Ref_Par = Ident_2;
+      break;
+    case Ident_4: break;
+    case Ident_5: 
+      *Enum_Ref_Par = Ident_3;
+      break;
+  } /* switch */
+} /* Proc_6 */
+
+void Proc_7 (Int_1_Par_Val, Int_2_Par_Val, Int_Par_Ref)
+One_Fifty       Int_1_Par_Val;
+One_Fifty       Int_2_Par_Val;
+One_Fifty      *Int_Par_Ref;
+/**********************************************/
+    /* executed three times                                      */ 
+    /* first call:      Int_1_Par_Val == 2, Int_2_Par_Val == 3,  */
+    /*                  Int_Par_Ref becomes 7                    */
+    /* second call:     Int_1_Par_Val == 10, Int_2_Par_Val == 5, */
+    /*                  Int_Par_Ref becomes 17                   */
+    /* third call:      Int_1_Par_Val == 6, Int_2_Par_Val == 10, */
+    /*                  Int_Par_Ref becomes 18                   */
+{
+  One_Fifty Int_Loc;
+
+  Int_Loc = Int_1_Par_Val + 2;
+  *Int_Par_Ref = Int_2_Par_Val + Int_Loc;
+} /* Proc_7 */
+
+
+void Proc_8 (Arr_1_Par_Ref, Arr_2_Par_Ref, Int_1_Par_Val, Int_2_Par_Val)
+/*********************************************************************/
+    /* executed once      */
+    /* Int_Par_Val_1 == 3 */
+    /* Int_Par_Val_2 == 7 */
+Arr_1_Dim       Arr_1_Par_Ref;
+Arr_2_Dim       Arr_2_Par_Ref;
+int             Int_1_Par_Val;
+int             Int_2_Par_Val;
+{
+  REG One_Fifty Int_Index;
+  REG One_Fifty Int_Loc;
+
+  Int_Loc = Int_1_Par_Val + 5;
+  Arr_1_Par_Ref [Int_Loc] = Int_2_Par_Val;
+  Arr_1_Par_Ref [Int_Loc+1] = Arr_1_Par_Ref [Int_Loc];
+  Arr_1_Par_Ref [Int_Loc+30] = Int_Loc;
+  for (Int_Index = Int_Loc; Int_Index <= Int_Loc+1; ++Int_Index)
+    Arr_2_Par_Ref [Int_Loc] [Int_Index] = Int_Loc;
+  Arr_2_Par_Ref [Int_Loc] [Int_Loc-1] += 1;
+  Arr_2_Par_Ref [Int_Loc+20] [Int_Loc] = Arr_1_Par_Ref [Int_Loc];
+  Int_Glob = 5;
+} /* Proc_8 */
+
+
+Enumeration Func_1 (Capital_Letter Ch_1_Par_Val, Capital_Letter Ch_2_Par_Val)
+/*************************************************/
+    /* executed three times                                         */
+    /* first call:      Ch_1_Par_Val == 'H', Ch_2_Par_Val == 'R'    */
+    /* second call:     Ch_1_Par_Val == 'A', Ch_2_Par_Val == 'C'    */
+    /* third call:      Ch_1_Par_Val == 'B', Ch_2_Par_Val == 'C'    */
+{
+  Capital_Letter        Ch_1_Loc;
+  Capital_Letter        Ch_2_Loc;
+
+  Ch_1_Loc = Ch_1_Par_Val;
+  Ch_2_Loc = Ch_1_Loc;
+  if (Ch_2_Loc != Ch_2_Par_Val)
+    /* then, executed */
+    return (Ident_1);
+  else  /* not executed */
+  {
+    Ch_1_Glob = Ch_1_Loc;
+    return (Ident_2);
+   }
+} /* Func_1 */
+
+
+
+Boolean Func_2 (Str_1_Par_Ref, Str_2_Par_Ref)
+/*************************************************/
+    /* executed once */
+    /* Str_1_Par_Ref == "DHRYSTONE PROGRAM, 1'ST STRING" */
+    /* Str_2_Par_Ref == "DHRYSTONE PROGRAM, 2'ND STRING" */
+
+Str_30  Str_1_Par_Ref;
+Str_30  Str_2_Par_Ref;
+{
+  REG One_Thirty        Int_Loc;
+      Capital_Letter    Ch_Loc;
+
+  Ch_Loc = 'A';
+  Int_Loc = 2;
+  while (Int_Loc <= 2) /* loop body executed once */
+    if (Func_1 (Str_1_Par_Ref[Int_Loc],
+                Str_2_Par_Ref[Int_Loc+1]) == Ident_1)
+      /* then, executed */
+    {
+      Ch_Loc = 'A';
+      Int_Loc += 1;
+    } /* if, while */
+  if (Ch_Loc >= 'W' && Ch_Loc < 'Z')
+    /* then, not executed */
+    Int_Loc = 7;
+  if (Ch_Loc == 'R')
+    /* then, not executed */
+    return (true);
+  else /* executed */
+  {
+    if (strcmp (Str_1_Par_Ref, Str_2_Par_Ref) > 0)
+      /* then, not executed */
+    {
+      Int_Loc += 7;
+      Int_Glob = Int_Loc;
+      return (true);
+    }
+    else /* executed */
+      return (false);
+  } /* if Ch_Loc */
+} /* Func_2 */
+
+
+Boolean Func_3 (Enum_Par_Val)
+/***************************/
+    /* executed once        */
+    /* Enum_Par_Val == Ident_3 */
+Enumeration Enum_Par_Val;
+{
+  Enumeration Enum_Loc;
+
+  Enum_Loc = Enum_Par_Val;
+  if (Enum_Loc == Ident_3)
+    /* then, executed */
+    return (true);
+  else /* not executed */
+    return (false);
+} /* Func_3 */