1 | /* |
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2 | * Cogent CSB336 Timer driver |
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3 | * |
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4 | * This uses timer 2 for timing measurments. |
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5 | * |
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6 | * Copyright (c) 2004 Cogent Computer Systems |
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7 | * Written by Jay Monkman <jtm@lopingdog.com> |
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8 | * |
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9 | * The license and distribution terms for this file may be |
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10 | * found in the file LICENSE in this distribution or at |
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11 | * |
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12 | * http://www.OARcorp.com/rtems/license.html. |
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13 | * |
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14 | * Notes: |
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15 | * This file manages the benchmark timer used by the RTEMS Timing Test |
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16 | * Suite. Each measured time period is demarcated by calls to |
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17 | * Timer_initialize() and Read_timer(). Read_timer() usually returns |
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18 | * the number of microseconds since Timer_initialize() exitted. |
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19 | * |
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20 | * It is important that the timer start/stop overhead be determined |
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21 | * when porting or modifying this code. |
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22 | * |
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23 | * timer.c,v 1.1 2002/11/13 17:55:09 joel Exp |
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24 | */ |
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25 | |
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26 | #include <rtems.h> |
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27 | #include <bsp.h> |
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28 | #include <mc9328mxl.h> |
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29 | |
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30 | uint32_t g_start; |
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31 | uint32_t g_freq; |
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32 | |
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33 | rtems_boolean Timer_driver_Find_average_overhead; |
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34 | |
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35 | |
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36 | /* |
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37 | * Set up Timer 1 |
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38 | */ |
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39 | void Timer_initialize( void ) |
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40 | { |
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41 | MC9328MXL_TMR2_TCTL = (MC9328MXL_TMR_TCTL_CLKSRC_PCLK1 | |
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42 | MC9328MXL_TMR_TCTL_FRR | |
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43 | MC9328MXL_TMR_TCTL_TEN); |
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44 | /* set prescaler to 1 (register value + 1) */ \ |
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45 | MC9328MXL_TMR2_TPRER = 0; |
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46 | |
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47 | /* get freq of counter in KHz */ |
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48 | g_freq = get_perclk1_freq() / 1000; |
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49 | |
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50 | g_start = MC9328MXL_TMR2_TCN; |
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51 | } |
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52 | |
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53 | /* |
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54 | * The following controls the behavior of Read_timer(). |
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55 | * |
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56 | * AVG_OVEREHAD is the overhead for starting and stopping the timer. It |
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57 | * is usually deducted from the number returned. |
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58 | * |
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59 | * LEAST_VALID is the lowest number this routine should trust. Numbers |
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60 | * below this are "noise" and zero is returned. |
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61 | */ |
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62 | |
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63 | #define AVG_OVERHEAD 0 /* It typically takes X.X microseconds */ |
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64 | /* (Y countdowns) to start/stop the timer. */ |
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65 | /* This value is in microseconds. */ |
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66 | #define LEAST_VALID 1 /* Don't trust a clicks value lower than this */ |
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67 | |
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68 | int Read_timer( void ) |
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69 | { |
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70 | uint32_t t; |
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71 | unsigned long long total; |
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72 | |
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73 | t = MC9328MXL_TMR2_TCN; |
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74 | /* |
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75 | * Total is calculated by taking into account the number of timer overflow |
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76 | * interrupts since the timer was initialized and clicks since the last |
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77 | * interrupts. |
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78 | */ |
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79 | |
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80 | total = (t - g_start); |
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81 | |
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82 | /* convert to nanoseconds */ |
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83 | total = (total * 1000)/ g_freq; |
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84 | |
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85 | if ( Timer_driver_Find_average_overhead == 1 ) { |
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86 | return (int) total; |
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87 | } else if ( total < LEAST_VALID ) { |
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88 | return 0; |
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89 | } |
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90 | /* |
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91 | * Somehow convert total into microseconds |
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92 | */ |
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93 | |
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94 | return (total - AVG_OVERHEAD); |
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95 | } |
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96 | |
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97 | /* |
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98 | * Empty function call used in loops to measure basic cost of looping |
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99 | * in Timing Test Suite. |
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100 | */ |
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101 | |
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102 | rtems_status_code Empty_function( void ) |
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103 | { |
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104 | return RTEMS_SUCCESSFUL; |
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105 | } |
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106 | |
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107 | void Set_find_average_overhead( |
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108 | rtems_boolean find_flag |
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109 | ) |
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110 | { |
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111 | Timer_driver_Find_average_overhead = find_flag; |
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112 | } |
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113 | |
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