1 | /* |
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2 | * Watchdog Handler |
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3 | * |
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4 | * |
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5 | * COPYRIGHT (c) 1989-1999. |
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6 | * On-Line Applications Research Corporation (OAR). |
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7 | * |
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8 | * The license and distribution terms for this file may be |
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9 | * found in the file LICENSE in this distribution or at |
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10 | * http://www.rtems.com/license/LICENSE. |
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11 | * |
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12 | * $Id$ |
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13 | */ |
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14 | |
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15 | #if HAVE_CONFIG_H |
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16 | #include "config.h" |
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17 | #endif |
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18 | |
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19 | #include <rtems/system.h> |
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20 | #include <rtems/score/isr.h> |
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21 | #include <rtems/score/watchdog.h> |
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22 | |
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23 | /*PAGE |
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24 | * |
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25 | * _Watchdog_Insert |
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26 | * |
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27 | * This routine inserts a watchdog timer on to the appropriate delta |
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28 | * chain while updating the delta interval counters. |
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29 | */ |
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30 | |
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31 | void _Watchdog_Insert( |
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32 | Chain_Control *header, |
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33 | Watchdog_Control *the_watchdog |
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34 | ) |
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35 | { |
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36 | ISR_Level level; |
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37 | Watchdog_Control *after; |
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38 | uint32_t insert_isr_nest_level; |
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39 | Watchdog_Interval delta_interval; |
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40 | |
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41 | |
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42 | insert_isr_nest_level = _ISR_Nest_level; |
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43 | |
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44 | _ISR_Disable( level ); |
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45 | |
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46 | /* |
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47 | * Check to see if the watchdog has just been inserted by a |
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48 | * higher priority interrupt. If so, abandon this insert. |
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49 | */ |
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50 | |
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51 | if ( the_watchdog->state != WATCHDOG_INACTIVE ) { |
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52 | _ISR_Enable( level ); |
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53 | return; |
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54 | } |
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55 | |
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56 | the_watchdog->state = WATCHDOG_BEING_INSERTED; |
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57 | _Watchdog_Sync_count++; |
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58 | |
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59 | restart: |
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60 | delta_interval = the_watchdog->initial; |
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61 | |
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62 | /* |
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63 | * We CANT use _Watchdog_First() here, because a TICK interrupt |
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64 | * could modify the chain during the _ISR_Flash() below. Hence, |
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65 | * the header is pointing to volatile data. The _Watchdog_First() |
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66 | * INLINE routine (but not the macro - note the subtle difference) |
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67 | * casts away the 'volatile'... |
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68 | * |
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69 | * Also, this is only necessary because we call no other routine |
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70 | * from this piece of code, hence the compiler thinks it's safe to |
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71 | * cache *header!! |
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72 | * |
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73 | * Till Straumann, 7/2003 (gcc-3.2.2 -O4 on powerpc) |
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74 | * |
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75 | */ |
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76 | for ( after = (Watchdog_Control *) ((volatile Chain_Control *)header)->first ; |
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77 | ; |
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78 | after = _Watchdog_Next( after ) ) { |
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79 | |
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80 | if ( delta_interval == 0 || !_Watchdog_Next( after ) ) |
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81 | break; |
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82 | |
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83 | if ( delta_interval < after->delta_interval ) { |
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84 | after->delta_interval -= delta_interval; |
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85 | break; |
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86 | } |
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87 | |
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88 | delta_interval -= after->delta_interval; |
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89 | |
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90 | /* |
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91 | * If you experience problems comment out the _ISR_Flash line. |
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92 | * 3.2.0 was the first release with this critical section redesigned. |
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93 | * Under certain circumstances, the PREVIOUS critical section algorithm |
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94 | * used around this flash point allowed interrupts to execute |
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95 | * which violated the design assumptions. The critical section |
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96 | * mechanism used here WAS redesigned to address this. |
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97 | */ |
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98 | |
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99 | _ISR_Flash( level ); |
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100 | |
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101 | if ( the_watchdog->state != WATCHDOG_BEING_INSERTED ) { |
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102 | goto exit_insert; |
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103 | } |
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104 | |
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105 | if ( _Watchdog_Sync_level > insert_isr_nest_level ) { |
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106 | _Watchdog_Sync_level = insert_isr_nest_level; |
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107 | goto restart; |
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108 | } |
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109 | } |
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110 | |
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111 | _Watchdog_Activate( the_watchdog ); |
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112 | |
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113 | the_watchdog->delta_interval = delta_interval; |
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114 | |
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115 | _Chain_Insert_unprotected( after->Node.previous, &the_watchdog->Node ); |
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116 | |
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117 | the_watchdog->start_time = _Watchdog_Ticks_since_boot; |
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118 | |
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119 | exit_insert: |
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120 | _Watchdog_Sync_level = insert_isr_nest_level; |
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121 | _Watchdog_Sync_count--; |
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122 | _ISR_Enable( level ); |
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123 | } |
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