source: rtems/c/src/lib/libcpu/arm/mc9328mxl/timer/timer.c @ 8fbe2e6

4.11
Last change on this file since 8fbe2e6 was 8fbe2e6, checked in by Joel Sherrill <joel.sherrill@…>, on Sep 4, 2014 at 1:59:49 PM

Use correct prototype of benchmark_timer_read()

This change starts with removing the effectively empty file
timerdrv.h. The prototypes for benchmark_timer_XXX() were in
btimer.h which was not universally used. Thus every use of
timerdrv.h had to be changed to btimer.h. Then the prototypes
for benchmark_timer_read() had to be adjusted to return
benchmark_timer_t rather than int or uint32_t.

I took this opportunity to also correct the file headers to
separate the copyright from the file description comments which
is needed to ensure the copyright isn't propagated into Doxygen
output.

  • Property mode set to 100644
File size: 2.3 KB
Line 
1/**
2 *  @file
3 *  @brief Cogent CSB336 Timer driver
4 *
5 * This uses timer 2 for timing measurments.
6 */
7
8/*
9 * Copyright (c) 2004 Cogent Computer Systems
10 *        Written by Jay Monkman <jtm@lopingdog.com>
11 *
12 *  The license and distribution terms for this file may be
13 *  found in the file LICENSE in this distribution or at
14 *  http://www.rtems.org/license/LICENSE.
15 */
16
17#include <rtems.h>
18#include <bsp.h>
19#include <rtems/btimer.h>
20#include <mc9328mxl.h>
21
22uint32_t g_start;
23uint32_t g_freq;
24
25bool benchmark_timer_find_average_overhead;
26
27
28/*
29 * Set up Timer 1
30 */
31void benchmark_timer_initialize( void )
32{
33    MC9328MXL_TMR2_TCTL = (MC9328MXL_TMR_TCTL_CLKSRC_PCLK1 |
34                            MC9328MXL_TMR_TCTL_FRR |
35                            MC9328MXL_TMR_TCTL_TEN);
36    /* set prescaler to 1 (register value + 1) */ \
37    MC9328MXL_TMR2_TPRER = 0;
38
39    /* get freq of counter in KHz */
40    g_freq = get_perclk1_freq() / 1000;
41
42    g_start =  MC9328MXL_TMR2_TCN;
43}
44
45/*
46 *  The following controls the behavior of benchmark_timer_read().
47 *
48 *  AVG_OVEREHAD is the overhead for starting and stopping the timer.  It
49 *  is usually deducted from the number returned.
50 *
51 *  LEAST_VALID is the lowest number this routine should trust.  Numbers
52 *  below this are "noise" and zero is returned.
53 */
54
55#define AVG_OVERHEAD      0  /* It typically takes X.X microseconds */
56                             /* (Y countdowns) to start/stop the timer. */
57                             /* This value is in microseconds. */
58#define LEAST_VALID       1  /* Don't trust a clicks value lower than this */
59
60benchmark_timer_t benchmark_timer_read( void )
61{
62  uint32_t t;
63  unsigned long long total;
64
65  t =  MC9328MXL_TMR2_TCN;
66  /*
67   *  Total is calculated by taking into account the number of timer overflow
68   *  interrupts since the timer was initialized and clicks since the last
69   *  interrupts.
70   */
71
72  total = (t - g_start);
73
74  /* convert to nanoseconds */
75  total = (total * 1000)/ g_freq;
76
77  if ( benchmark_timer_find_average_overhead == 1 ) {
78    return (int) total;
79  } else if ( total < LEAST_VALID ) {
80      return 0;
81  }
82  /*
83   *  Somehow convert total into microseconds
84   */
85
86  return (total - AVG_OVERHEAD);
87}
88
89void benchmark_timer_disable_subtracting_average_overhead(bool find_flag)
90{
91  benchmark_timer_find_average_overhead = find_flag;
92}
93
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