source: rtems/c/src/lib/libcpu/powerpc/mpc8xx/timer/timer.c @ d1dde59

4.104.114.95
Last change on this file since d1dde59 was d1dde59, checked in by Joel Sherrill <joel.sherrill@…>, on Sep 8, 2008 at 4:29:52 PM

2008-09-08 Joel Sherrill <joel.sherrill@…>

  • mpc8xx/clock/clock.c, mpc8xx/console-generic/console-generic.c, mpc8xx/timer/timer.c: Fix nested extern declaration warnings.
  • Property mode set to 100644
File size: 2.8 KB
Line 
1/*  timer.c
2 *
3 *  This file manages the interval timer on the PowerPC MPC8xx.
4 *  NOTE: This is not the PIT, but rather the RTEMS interval
5 *        timer
6 *  We shall use the bottom 32 bits of the timebase register,
7 *
8 *  The following was in the 403 version of this file. I don't
9 *  know what it means. JTM 5/19/98
10 *  NOTE: It is important that the timer start/stop overhead be
11 *        determined when porting or modifying this code.
12 *
13 *  Author: Jay Monkman (jmonkman@frasca.com)
14 *  Copywright (C) 1998 by Frasca International, Inc.
15 *
16 *  Derived from c/src/lib/libcpu/ppc/ppc403/timer/timer.c:
17 *
18 *  Author:     Andrew Bray <andy@i-cubed.co.uk>
19 *
20 *  COPYRIGHT (c) 1995 by i-cubed ltd.
21 *
22 *  To anyone who acknowledges that this file is provided "AS IS"
23 *  without any express or implied warranty:
24 *      permission to use, copy, modify, and distribute this file
25 *      for any purpose is hereby granted without fee, provided that
26 *      the above copyright notice and this notice appears in all
27 *      copies, and that the name of i-cubed limited not be used in
28 *      advertising or publicity pertaining to distribution of the
29 *      software without specific, written prior permission.
30 *      i-cubed limited makes no representations about the suitability
31 *      of this software for any purpose.
32 *
33 *  Derived from c/src/lib/libcpu/hppa1_1/timer/timer.c:
34 *
35 *  COPYRIGHT (c) 1989-2007.
36 *  On-Line Applications Research Corporation (OAR).
37 *
38 *  The license and distribution terms for this file may be
39 *  found in the file LICENSE in this distribution or at
40 *  http://www.rtems.com/license/LICENSE.
41 *
42 *  $Id$
43 */
44
45#include <rtems.h>
46#include <mpc8xx.h>
47
48static volatile uint32_t   Timer_starting;
49static bool benchmark_timer_find_average_overhead;
50extern uint32_t bsp_timer_least_valid;
51extern uint32_t bsp_timer_average_overhead;
52
53/*
54 *  This is so small that this code will be reproduced where needed.
55 */
56static inline uint32_t   get_itimer(void)
57{
58   uint32_t   ret;
59
60   asm volatile ("mftb %0" : "=r" ((ret))); /* TBLO */
61
62   return ret;
63}
64
65void benchmark_timer_initialize(void)
66{
67  /* set interrupt level and enable timebase. This should never */
68  /*  generate an interrupt however. */
69  m8xx.tbscr |= M8xx_TBSCR_TBIRQ(4) | M8xx_TBSCR_TBE;
70 
71  Timer_starting = get_itimer();
72}
73
74int benchmark_timer_read(void)
75{
76  uint32_t   clicks;
77  uint32_t   total;
78
79  clicks = get_itimer();
80
81  total = clicks - Timer_starting;
82
83  if ( benchmark_timer_find_average_overhead == 1 )
84    return total;          /* in XXX microsecond units */
85
86  else {
87    if ( total < bsp_timer_least_valid ) {
88      return 0;            /* below timer resolution */
89    }
90    return (total - bsp_timer_average_overhead);
91  }
92}
93
94void benchmark_timer_disable_subtracting_average_overhead(bool find_flag)
95{
96  benchmark_timer_find_average_overhead = find_flag;
97}
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