source: rtems/c/src/lib/libcpu/powerpc/mpc8xx/timer/timer.c @ 8ef3818

4.104.114.84.95
Last change on this file since 8ef3818 was 8ef3818, checked in by Joel Sherrill <joel.sherrill@…>, on Jun 12, 2000 at 7:57:02 PM

Patch from John Cotton <john.cotton@…>, Charles-Antoine Gauthier
<charles.gauthier@…>, and Darlene A. Stewart
<Darlene.Stewart@…> to add support for a number of very
significant things:

+ BSPs for many variations on the Motorola MBX8xx board series
+ Cache Manager including initial support for m68040

and PowerPC

+ Rework of mpc8xx libcpu code so all mpc8xx CPUs now use

same code base.

+ Rework of eth_comm BSP to utiltize above.

John reports this works on the 821 and 860

  • 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 <bsp.h>
47#include <rtems.h>
48#include <mpc8xx.h>
49
50extern rtems_cpu_table           Cpu_table;             /* owned by BSP */
51
52static volatile rtems_unsigned32 Timer_starting;
53static rtems_boolean Timer_driver_Find_average_overhead;
54
55/*
56 *  This is so small that this code will be reproduced where needed.
57 */
58static inline rtems_unsigned32 get_itimer(void)
59{
60   rtems_unsigned32 ret;
61
62   asm volatile ("mftb %0" : "=r" ((ret))); /* TBLO */
63
64   return ret;
65}
66
67void Timer_initialize(void)
68{
69  /* set interrupt level and enable timebase. This should never */
70  /*  generate an interrupt however. */
71  m8xx.tbscr |= M8xx_TBSCR_TBIRQ(4) | M8xx_TBSCR_TBE;
72 
73  Timer_starting = get_itimer();
74}
75
76int Read_timer(void)
77{
78  rtems_unsigned32 clicks;
79  rtems_unsigned32 total;
80
81  clicks = get_itimer();
82
83  total = clicks - Timer_starting;
84
85  if ( Timer_driver_Find_average_overhead == 1 )
86    return total;          /* in XXX microsecond units */
87
88  else {
89    if ( total < Cpu_table.timer_least_valid ) {
90      return 0;            /* below timer resolution */
91    }
92    return (total - Cpu_table.timer_average_overhead);
93  }
94}
95
96rtems_status_code Empty_function(void)
97{
98  return RTEMS_SUCCESSFUL;
99}
100
101void Set_find_average_overhead(rtems_boolean find_flag)
102{
103  Timer_driver_Find_average_overhead = find_flag;
104}
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