source: rtems/c/src/lib/libcpu/powerpc/mpc5xx/timer/timer.c @ 73b5bd5d

4.104.114.84.95
Last change on this file since 73b5bd5d was 8430205, checked in by Joel Sherrill <joel.sherrill@…>, on Apr 12, 2004 at 10:04:28 PM

2004-04-12 David Querbach <querbach@…>

  • README, configure.ac, mpc5xx/Makefile.am, mpc5xx/exceptions/raw_exception.c, mpc5xx/exceptions/raw_exception.h, mpc5xx/timer/timer.c, shared/include/cpuIdent.h: addition of a significant amount of MPC5xx support as part of the addition of the SS555 BSP.
  • mpc5xx/README, mpc5xx/clock/clock.c, mpc5xx/console-generic/console-generic.c, mpc5xx/include/console.h, mpc5xx/include/mpc5xx.h, mpc5xx/irq/irq.c, mpc5xx/irq/irq.h, mpc5xx/irq/irq_asm.S, mpc5xx/irq/irq_init.c, mpc5xx/vectors/vectors.S, mpc5xx/vectors/vectors.h, mpc5xx/vectors/vectors_init.c: New files.
  • mpc5xx/exceptions/asm_utils.S: Removed.
  • Property mode set to 100644
File size: 3.5 KB
Line 
1/*  timer.c
2 *
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,
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 *
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 *
41 *  COPYRIGHT (c) 1989-1998.
42 *  On-Line Applications Research Corporation (OAR).
43 *
44 *  The license and distribution terms for this file may be
45 *  found in the file LICENSE in this distribution or at
46 *  http://www.rtems.com/license/LICENSE.
47 *
48 *  $Id$
49 */
50
51#include <rtems.h>
52#include <mpc5xx.h>
53
54static volatile rtems_unsigned32 Timer_starting;
55static rtems_boolean Timer_driver_Find_average_overhead;
56
57/*
58 *  This is so small that this code will be reproduced where needed.
59 */
60static inline rtems_unsigned32 get_itimer(void)
61{
62   rtems_unsigned32 ret;
63
64   asm volatile ("mftb %0" : "=r" ((ret))); /* TBLO */
65
66   return ret;
67}
68
69void Timer_initialize(void)
70{
71  /* set interrupt level and enable timebase. This should never */
72  /*  generate an interrupt however. */
73  usiu.tbscrk = USIU_UNLOCK_KEY;
74  usiu.tbscr |= USIU_TBSCR_TBIRQ(4)     /* interrupt priority level */
75              | USIU_TBSCR_TBF          /* freeze timebase during debug */
76              | USIU_TBSCR_TBE;         /* enable timebase */
77  usiu.tbscrk = 0;
78 
79  Timer_starting = get_itimer();
80}
81
82#ifndef  rtems_cpu_configuration_get_timer_least_valid
83#define  rtems_cpu_configuration_get_timer_least_valid() 0
84#endif
85
86#ifndef  rtems_cpu_configuration_get_timer_average_overhead
87#define  rtems_cpu_configuration_get_timer_average_overhead() 0
88#endif
89
90int Read_timer(void)
91{
92  rtems_unsigned32 clicks;
93  rtems_unsigned32 total;
94
95  clicks = get_itimer();
96
97  total = clicks - Timer_starting;
98
99  if ( Timer_driver_Find_average_overhead == 1 )
100    return total;          /* in XXX microsecond units */
101
102  else {
103    if ( total < rtems_cpu_configuration_get_timer_least_valid() ) {
104      return 0;            /* below timer resolution */
105    }
106    return (total - rtems_cpu_configuration_get_timer_average_overhead());
107  }
108}
109
110rtems_status_code Empty_function(void)
111{
112  return RTEMS_SUCCESSFUL;
113}
114
115void Set_find_average_overhead(rtems_boolean find_flag)
116{
117  Timer_driver_Find_average_overhead = find_flag;
118}
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