source: rtems/c/src/lib/libcpu/bfin/timer/timer.c @ 30abd24

4.104.114.95
Last change on this file since 30abd24 was 30abd24, checked in by Joel Sherrill <joel.sherrill@…>, on 08/15/08 at 20:18:41

2008-08-15 Allan Hessenflow <allanh@…>

  • ChangeLog?, Makefile.am, README, configure.ac, preinstall.am, cache/cache.c, cache/cache_.h, clock/clock.c, clock/rtc.c, clock/tod.h, include/bf533.h, include/bf537.h, include/cecRegs.h, include/coreTimerRegs.h, include/dmaRegs.h, include/ebiuRegs.h, include/ethernetRegs.h, include/gpioRegs.h, include/memoryRegs.h, include/mmuRegs.h, include/ppiRegs.h, include/rtcRegs.h, include/sicRegs.h, include/spiRegs.h, include/sportRegs.h, include/timerRegs.h, include/twiRegs.h, include/uartRegs.h, include/wdogRegs.h, interrupt/interrupt.c, interrupt/interrupt.h, mmu/mmu.c, mmu/mmu.h, network/ethernet.c, network/ethernet.h, serial/spi.c, serial/spi.h, serial/sport.c, serial/sport.h, serial/twi.c, serial/twi.h, serial/uart.c, serial/uart.h, timer/timer.c: New files.
  • Property mode set to 100644
File size: 2.6 KB
Line 
1/*  Timer for Blackfin
2 *
3 *  This file manages the benchmark timer used by the RTEMS Timing Test
4 *  Suite.  Each measured time period is demarcated by calls to
5 *  Timer_initialize() and Read_timer().  Read_timer() usually returns
6 *  the number of microseconds since Timer_initialize() exitted.
7 * 
8 *  Copyright (c) 2006 by Atos Automacao Industrial Ltda.
9 *             written by Alain Schaefer <alain.schaefer@easc.ch>
10 *                    and Antonio Giovanini <antonio@atos.com.br>
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.com/license/LICENSE.
15 *
16 *  $Id$
17 */
18 
19
20#include <rtems.h>
21#include <bsp.h>
22
23
24uint32_t         Timer_interrupts;
25rtems_boolean Timer_driver_Find_average_overhead;
26
27/*
28 * Timer_initialize
29 *
30 * Blackfin processor has a counter for clock cycles.
31 */
32void Timer_initialize( void )
33{
34
35  /*reset counters*/
36  asm ("R2 = 0;");
37  asm ("CYCLES = R2;");
38  asm ("CYCLES2 = R2;");
39  /*start counters*/
40  asm ("R2 = SYSCFG;");
41  asm ("BITSET(R2,1);");
42  asm ("SYSCFG = R2");
43 
44}
45
46/*
47 *  The following controls the behavior of Read_timer().
48 *
49 *  AVG_OVEREHAD is the overhead for starting and stopping the timer.  It
50 *  is usually deducted from the number returned.
51 *
52 *  LEAST_VALID is the lowest number this routine should trust.  Numbers
53 *  below this are "noise" and zero is returned.
54 */
55
56#define AVG_OVERHEAD      0  /* It typically takes X.X microseconds */
57                             /* (Y countdowns) to start/stop the timer. */
58                             /* This value is in microseconds. */
59#define LEAST_VALID       1  /* Don't trust a clicks value lower than this */
60
61int Read_timer( void )
62{
63  uint32_t          clicks;
64  uint32_t          total;
65  register uint32_t cycles asm ("R2");
66
67  /* stop counter */
68  asm("R2 = SYSCFG;");
69  asm("BITCLR(R2,1);");
70  asm("SYSCFG = R2;");
71  asm("R2 = CYCLES;");
72
73
74  clicks = cycles; /* Clock cycles */
75
76  /* converting to microseconds */
77  total = clicks / (CCLK/1000000);
78
79  if ( Timer_driver_Find_average_overhead == 1 )
80    return total;          /* in XXX microsecond units */
81  else {
82    if ( total < LEAST_VALID )
83      return 0;            /* below timer resolution */
84  /*
85   *  Somehow convert total into microseconds
86   */
87      return (total - AVG_OVERHEAD);
88    }
89}
90
91/*
92 *  Empty function call used in loops to measure basic cost of looping
93 *  in Timing Test Suite.
94 */
95
96rtems_status_code Empty_function( void )
97{
98  return RTEMS_SUCCESSFUL;
99}
100
101void Set_find_average_overhead(
102  rtems_boolean find_flag
103)
104{
105  Timer_driver_Find_average_overhead = find_flag;
106}
Note: See TracBrowser for help on using the repository browser.