source: rtems/c/src/lib/libcpu/powerpc/mpc5xx/timer/timer.c @ c499856

4.11
Last change on this file since c499856 was c499856, checked in by Chris Johns <chrisj@…>, on Mar 20, 2014 at 9:10:47 PM

Change all references of rtems.com to rtems.org.

  • Property mode set to 100644
File size: 3.2 KB
RevLine 
[0aee2be5]1/*  timer.c
2 *
[8430205]3 *  This file manages the interval timer on the PowerPC MPC5xx.
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,
[0aee2be5]7 *
[8430205]8 *  The following was in the 403 version of this file. I don't
9 *  know what it means. JTM 5/19/98
[0aee2be5]10 *  NOTE: It is important that the timer start/stop overhead be
11 *        determined when porting or modifying this code.
12 *
[8430205]13 *
14 *  MPC5xx port sponsored by Defence Research and Development Canada - Suffield
15 *  Copyright (C) 2004, Real-Time Systems Inc. (querbach@realtime.bc.ca)
16 *
17 *  Derived from c/src/lib/libcpu/powerpc/mpc8xx/timer/timer.c:
18 *
19 *  Author: Jay Monkman (jmonkman@frasca.com)
20 *  Copywright (C) 1998 by Frasca International, Inc.
21 *
22 *  Derived from c/src/lib/libcpu/ppc/ppc403/timer/timer.c:
23 *
24 *  Author:     Andrew Bray <andy@i-cubed.co.uk>
25 *
26 *  COPYRIGHT (c) 1995 by i-cubed ltd.
27 *
28 *  To anyone who acknowledges that this file is provided "AS IS"
29 *  without any express or implied warranty:
30 *      permission to use, copy, modify, and distribute this file
31 *      for any purpose is hereby granted without fee, provided that
32 *      the above copyright notice and this notice appears in all
33 *      copies, and that the name of i-cubed limited not be used in
34 *      advertising or publicity pertaining to distribution of the
35 *      software without specific, written prior permission.
36 *      i-cubed limited makes no representations about the suitability
37 *      of this software for any purpose.
38 *
39 *  Derived from c/src/lib/libcpu/hppa1_1/timer/timer.c:
40 *
[c4cc8199]41 *  COPYRIGHT (c) 1989-2007.
[0aee2be5]42 *  On-Line Applications Research Corporation (OAR).
43 *
[8430205]44 *  The license and distribution terms for this file may be
45 *  found in the file LICENSE in this distribution or at
[c499856]46 *  http://www.rtems.org/license/LICENSE.
[0aee2be5]47 */
48
49#include <rtems.h>
[8430205]50#include <mpc5xx.h>
51
[ad17f7f]52static volatile uint32_t Timer_starting;
[3942cce]53static bool benchmark_timer_find_average_overhead;
[8430205]54
[14a78df]55extern uint32_t bsp_timer_least_valid;
56extern uint32_t bsp_timer_average_overhead;
57
[8430205]58/*
59 *  This is so small that this code will be reproduced where needed.
60 */
[ad17f7f]61static inline uint32_t get_itimer(void)
[8430205]62{
[ad17f7f]63   uint32_t ret;
[0aee2be5]64
[f9acc33]65   __asm__ volatile ("mftb %0" : "=r" ((ret))); /* TBLO */
[0aee2be5]66
[8430205]67   return ret;
68}
[0aee2be5]69
[6427f1a]70void benchmark_timer_initialize(void)
[0aee2be5]71{
[8430205]72  /* set interrupt level and enable timebase. This should never */
73  /*  generate an interrupt however. */
74  usiu.tbscrk = USIU_UNLOCK_KEY;
75  usiu.tbscr |= USIU_TBSCR_TBIRQ(4)     /* interrupt priority level */
76              | USIU_TBSCR_TBF          /* freeze timebase during debug */
77              | USIU_TBSCR_TBE;         /* enable timebase */
78  usiu.tbscrk = 0;
[359e537]79
[8430205]80  Timer_starting = get_itimer();
[0aee2be5]81}
82
[6427f1a]83int benchmark_timer_read(void)
[0aee2be5]84{
[ad17f7f]85  uint32_t clicks;
86  uint32_t total;
[0aee2be5]87
[8430205]88  clicks = get_itimer();
89
90  total = clicks - Timer_starting;
91
[6427f1a]92  if ( benchmark_timer_find_average_overhead == 1 )
[8430205]93    return total;          /* in XXX microsecond units */
94
95  else {
[c4cc8199]96    if ( total < bsp_timer_least_valid ) {
[8430205]97      return 0;            /* below timer resolution */
98    }
[c4cc8199]99    return (total - bsp_timer_average_overhead);
[8430205]100  }
101}
[0aee2be5]102
[3942cce]103void benchmark_timer_disable_subtracting_average_overhead(bool find_flag)
[0aee2be5]104{
[6427f1a]105  benchmark_timer_find_average_overhead = find_flag;
[0aee2be5]106}
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