| 1 |
30 |
unneback |
/* timer.c
|
| 2 |
|
|
*
|
| 3 |
|
|
* This file manages the interval timer on the PowerPC MPC821.
|
| 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) 1989-1999.
|
| 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.OARcorp.com/rtems/license.html.
|
| 41 |
|
|
*
|
| 42 |
|
|
* $Id: timer.c,v 1.2 2001-09-27 12:01:28 chris Exp $
|
| 43 |
|
|
*/
|
| 44 |
|
|
|
| 45 |
|
|
#include <rtems.h>
|
| 46 |
|
|
#include <mpc821.h>
|
| 47 |
|
|
|
| 48 |
|
|
static volatile rtems_unsigned32 Timer_starting;
|
| 49 |
|
|
static rtems_boolean Timer_driver_Find_average_overhead;
|
| 50 |
|
|
|
| 51 |
|
|
/*
|
| 52 |
|
|
* This is so small that this code will be reproduced where needed.
|
| 53 |
|
|
*/
|
| 54 |
|
|
static inline rtems_unsigned32 get_itimer(void)
|
| 55 |
|
|
{
|
| 56 |
|
|
rtems_unsigned32 ret;
|
| 57 |
|
|
|
| 58 |
|
|
asm volatile ("mftb %0" : "=r" ((ret))); /* TBLO */
|
| 59 |
|
|
|
| 60 |
|
|
return ret;
|
| 61 |
|
|
}
|
| 62 |
|
|
|
| 63 |
|
|
void Timer_initialize(void)
|
| 64 |
|
|
{
|
| 65 |
|
|
/* set interrupt level and enable timebase. This should never */
|
| 66 |
|
|
/* generate an interrupt however. */
|
| 67 |
|
|
m821.tbscr |= M821_TBSCR_TBIRQ(4) | M821_TBSCR_TBE;
|
| 68 |
|
|
|
| 69 |
|
|
Timer_starting = get_itimer();
|
| 70 |
|
|
}
|
| 71 |
|
|
|
| 72 |
|
|
int Read_timer(void)
|
| 73 |
|
|
{
|
| 74 |
|
|
rtems_unsigned32 clicks;
|
| 75 |
|
|
rtems_unsigned32 total;
|
| 76 |
|
|
|
| 77 |
|
|
clicks = get_itimer();
|
| 78 |
|
|
|
| 79 |
|
|
total = clicks - Timer_starting;
|
| 80 |
|
|
|
| 81 |
|
|
if ( Timer_driver_Find_average_overhead == 1 )
|
| 82 |
|
|
return total; /* in XXX microsecond units */
|
| 83 |
|
|
|
| 84 |
|
|
else {
|
| 85 |
|
|
if ( total < rtems_cpu_configuration_get_timer_least_valid() ) {
|
| 86 |
|
|
return 0; /* below timer resolution */
|
| 87 |
|
|
}
|
| 88 |
|
|
return (total - rtems_cpu_configuration_get_timer_average_overhead());
|
| 89 |
|
|
}
|
| 90 |
|
|
}
|
| 91 |
|
|
|
| 92 |
|
|
rtems_status_code Empty_function(void)
|
| 93 |
|
|
{
|
| 94 |
|
|
return RTEMS_SUCCESSFUL;
|
| 95 |
|
|
}
|
| 96 |
|
|
|
| 97 |
|
|
void Set_find_average_overhead(rtems_boolean find_flag)
|
| 98 |
|
|
{
|
| 99 |
|
|
Timer_driver_Find_average_overhead = find_flag;
|
| 100 |
|
|
}
|
