source: rtems/c/src/lib/libcpu/m68k/mcf5272/timer/timer.c @ f68401e

4.115
Last change on this file since f68401e was 1c554014, checked in by Ralf Corsépius <ralf.corsepius@…>, on 07/19/12 at 14:14:53

Remove CVS-Ids.
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File size: 4.4 KB
Line 
1/*
2 *  Timer Init
3 *
4 *  This module initializes TIMER 2 for on the MCF5272 for benchmarks.
5 *
6 *  Copyright (C) 2000 OKTET Ltd., St.-Petersburg, Russia
7 *  Author: Victor V. Vengerov <vvv@oktet.ru>
8 *
9 *  Based on work:
10 *  Author:
11 *    David Fiddes, D.J@fiddes.surfaid.org
12 *    http://www.calm.hw.ac.uk/davidf/coldfire/
13 *
14 *  COPYRIGHT (c) 1989-1998.
15 *  On-Line Applications Research Corporation (OAR).
16 *
17 *  The license and distribution terms for this file may be
18 *  found in the file LICENSE in this distribution or at
19 *  http://www.rtems.com/license/LICENSE.
20 */
21
22#include <rtems.h>
23#include <bsp.h>
24#include <mcf5272/mcf5272.h>
25
26#define TRR2_VAL 65530
27
28uint32_t Timer_interrupts;
29
30bool benchmark_timer_find_average_overhead;
31
32/* External assembler interrupt handler routine */
33extern rtems_isr timerisr(rtems_vector_number vector);
34
35
36/* benchmark_timer_initialize --
37 *     Initialize timer 2 for accurate time measurement.
38 *
39 * PARAMETERS:
40 *     none
41 *
42 * RETURNS:
43 *     none
44 */
45void
46benchmark_timer_initialize(void)
47{
48    uint32_t icr;
49    /* Catch timer2 interrupts */
50    set_vector(timerisr, BSP_INTVEC_TMR2, 0);
51
52    /* Reset Timer */
53    g_timer_regs->tmr2 = MCF5272_TMR_RST;
54    g_timer_regs->tmr2 = MCF5272_TMR_CLK_STOP;
55    g_timer_regs->tmr2 = MCF5272_TMR_RST;
56    g_timer_regs->tcn2 = 0;  /* reset counter */
57    Timer_interrupts   = 0;  /* Clear timer ISR counter */
58    g_timer_regs->ter2 = MCF5272_TER_REF | MCF5272_TER_CAP;
59    g_timer_regs->trr2 = TRR2_VAL -1 ;
60
61
62    /* Set Timer 2 prescaler so that it counts in microseconds */
63    g_timer_regs->tmr2 = (
64        (((BSP_SYSTEM_FREQUENCY / 1000000) - 1) << MCF5272_TMR_PS_SHIFT) |
65        MCF5272_TMR_CE_DISABLE                                           |
66        MCF5272_TMR_ORI                                                  |
67        MCF5272_TMR_FRR                                                  |
68        MCF5272_TMR_CLK_MSTR                                             |
69        MCF5272_TMR_RST);
70
71    /* Initialize interrupts for timer2 */
72    icr = g_intctrl_regs->icr1;
73    icr = icr & ~(MCF5272_ICR1_TMR2_MASK | MCF5272_ICR1_TMR2_PI);
74    icr |= (MCF5272_ICR1_TMR2_IPL(BSP_INTLVL_TMR2) | MCF5272_ICR1_TMR2_PI);
75    g_intctrl_regs->icr1 = icr;
76
77}
78
79/*
80 *  The following controls the behavior of benchmark_timer_read().
81 *
82 *  FIND_AVG_OVERHEAD *  instructs the routine to return the "raw" count.
83 *
84 *  AVG_OVEREHAD is the overhead for starting and stopping the timer.  It
85 *  is usually deducted from the number returned.
86 *
87 *  LEAST_VALID is the lowest number this routine should trust.  Numbers
88 *  below this are "noise" and zero is returned.
89 */
90
91#define AVG_OVERHEAD      0  /* It typically takes 2.0 microseconds */
92                             /* (Y countdowns) to start/stop the timer. */
93                             /* This value is in microseconds. */
94#define LEAST_VALID       1  /* Don't trust a clicks value lower than this */
95
96/* benchmark_timer_read --
97 *     Read timer value in microsecond units since timer start.
98 *
99 * PARAMETERS:
100 *     none
101 *
102 * RETURNS:
103 *     number of microseconds since timer has been started
104 */
105int
106benchmark_timer_read( void )
107{
108    uint16_t clicks;
109    uint32_t total;
110
111    /*
112     *  Read the timer and see how many clicks it has been since counter
113     *  rolled over.
114     */
115    clicks = g_timer_regs->tcn2;
116
117    /* Stop Timer... */
118    g_timer_regs->tmr2 = MCF5272_TMR_CLK_STOP | MCF5272_TMR_RST;
119
120    /*
121     *  Total is calculated by taking into account the number of timer
122     *  overflow interrupts since the timer was initialized and clicks
123     *  since the last interrupts.
124     */
125
126    total = (Timer_interrupts * TRR2_VAL) + clicks;
127
128    if ( benchmark_timer_find_average_overhead == 1 )
129        return total;          /* in XXX microsecond units */
130
131    if ( total < LEAST_VALID )
132        return 0;            /* below timer resolution */
133
134    /*
135     *  Return the count in microseconds
136     */
137    return (total - AVG_OVERHEAD);
138}
139
140/* benchmark_timer_disable_subtracting_average_overhead --
141 *     This routine is invoked by the "Check Timer" (tmck) test in the
142 *     RTEMS Timing Test Suite. It makes the benchmark_timer_read routine not
143 *     subtract the overhead required to initialize and read the benchmark
144 *     timer.
145 *
146 * PARAMETERS:
147 *     find_flag - bool flag, true if overhead must not be subtracted.
148 *
149 * RETURNS:
150 *     none
151 */
152void
153benchmark_timer_disable_subtracting_average_overhead(bool find_flag)
154{
155  benchmark_timer_find_average_overhead = find_flag;
156}
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