source: rtems/c/src/lib/libcpu/powerpc/mpc8xx/timer/timer.c @ 61bd0301

4.104.114.84.95
Last change on this file since 61bd0301 was 61bd0301, checked in by Joel Sherrill <joel.sherrill@…>, on 06/14/00 at 15:52:24

Moved PowerPC cache management code to libcpu. Also compiled
mpc8xx libcpu support for the first time and remove includes
of bsp.h, references to BSP_Configuration, and Cpu_table. All
of these can be obtained directly from RTEMS now.

  • Property mode set to 100644
File size: 2.9 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) 1989-1998.
36 *  On-Line Applications Research Corporation (OAR).
37 *  Copyright assigned to U.S. Government, 1994.
38 *
39 *  The license and distribution terms for this file may be
40 *  found in the file LICENSE in this distribution or at
41 *  http://www.OARcorp.com/rtems/license.html.
42 *
43 *  $Id$
44 */
45
46#include <rtems.h>
47#include <mpc8xx.h>
48
49static volatile rtems_unsigned32 Timer_starting;
50static rtems_boolean Timer_driver_Find_average_overhead;
51
52/*
53 *  This is so small that this code will be reproduced where needed.
54 */
55static inline rtems_unsigned32 get_itimer(void)
56{
57   rtems_unsigned32 ret;
58
59   asm volatile ("mftb %0" : "=r" ((ret))); /* TBLO */
60
61   return ret;
62}
63
64void Timer_initialize(void)
65{
66  /* set interrupt level and enable timebase. This should never */
67  /*  generate an interrupt however. */
68  m8xx.tbscr |= M8xx_TBSCR_TBIRQ(4) | M8xx_TBSCR_TBE;
69 
70  Timer_starting = get_itimer();
71}
72
73int Read_timer(void)
74{
75  rtems_unsigned32 clicks;
76  rtems_unsigned32 total;
77
78  clicks = get_itimer();
79
80  total = clicks - Timer_starting;
81
82  if ( Timer_driver_Find_average_overhead == 1 )
83    return total;          /* in XXX microsecond units */
84
85  else {
86    if ( total < rtems_cpu_configuration_get_timer_least_valid() ) {
87      return 0;            /* below timer resolution */
88    }
89    return (total - rtems_cpu_configuration_get_timer_average_overhead());
90  }
91}
92
93rtems_status_code Empty_function(void)
94{
95  return RTEMS_SUCCESSFUL;
96}
97
98void Set_find_average_overhead(rtems_boolean find_flag)
99{
100  Timer_driver_Find_average_overhead = find_flag;
101}
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