1 | /* |
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2 | (C) Copyright IBM Corp. 2008 |
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3 | |
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4 | All rights reserved. |
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5 | |
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6 | Redistribution and use in source and binary forms, with or without |
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7 | modification, are permitted provided that the following conditions are met: |
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8 | |
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9 | * Redistributions of source code must retain the above copyright notice, |
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10 | this list of conditions and the following disclaimer. |
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11 | * Redistributions in binary form must reproduce the above copyright |
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12 | notice, this list of conditions and the following disclaimer in the |
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13 | documentation and/or other materials provided with the distribution. |
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14 | * Neither the name of IBM nor the names of its contributors may be |
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15 | used to endorse or promote products derived from this software without |
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16 | specific prior written permission. |
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17 | |
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18 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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19 | AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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20 | IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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21 | ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
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22 | LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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23 | CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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24 | SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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25 | INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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26 | CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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27 | ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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28 | POSSIBILITY OF SUCH DAMAGE. |
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29 | */ |
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30 | |
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31 | /* Second Level Interrupt handler and related services for SPU timers. */ |
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32 | #include "spu_timer_internal.h" |
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33 | /* Resets decrementer to the specified value. Also updates software timebase |
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34 | to account for the time between the last decrementer reset and now. There |
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35 | are two cases: |
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36 | * Called by application to start a new timer. |
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37 | * Called by spu_clock to active the next timer. |
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38 | In both cases, the amount of time is the current interval timeout minus the |
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39 | current decrementer value. */ |
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40 | void |
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41 | __reset_spu_decr (int val) |
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42 | { |
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43 | |
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44 | /* The interrupt occurs when the msb goes from 0 to 1 or when the decrementer |
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45 | goes from 0 to -1. To be precisely accurate we should set the timer to |
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46 | the intverval -1, unless the interval passed in is 0 in which case it |
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47 | should be left at 0. */ |
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48 | int enable_val = (__likely (val)) ? val - 1 : 0; |
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49 | |
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50 | /* Decrementer must be stopped before writing it - minimize the time |
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51 | stopped. */ |
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52 | unsigned mask = __disable_spu_decr (); |
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53 | |
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54 | /* Perform tb correction before resettting the decrementer. the corrected |
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55 | value is the current timeout value minus the current decrementer value. |
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56 | Occasionally the read returns 0 - a second read will clear this |
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57 | condition. */ |
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58 | spu_readch (SPU_RdDec); |
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59 | int decval = spu_readch (SPU_RdDec); |
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60 | /* Restart decrementer with next timeout val. */ |
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61 | __enable_spu_decr (enable_val, mask); |
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62 | |
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63 | /* Update the timebase values before enabling for interrupts. */ |
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64 | __spu_tb_val += __spu_tb_timeout - decval; |
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65 | __spu_tb_timeout = enable_val; |
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66 | } |
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67 | |
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68 | /* Update software timebase and timeout value for the 'next to expire' timer. |
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69 | Called when starting a new timer so the timer list will have timeouts |
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70 | relative to the current time. */ |
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71 | static inline void |
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72 | __update_spu_tb_val (void) |
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73 | { |
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74 | int elapsed = __spu_tb_timeout - spu_readch (SPU_RdDec); |
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75 | #ifdef SPU_TIMER_DEBUG |
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76 | if (elapsed < 0) |
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77 | ABORT (); |
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78 | #endif |
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79 | __spu_tb_val += elapsed; |
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80 | |
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81 | /* Adjust the timeout for the timer next to expire. Note this could cause |
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82 | the timeout to go negative, if it was just about to expire when we called |
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83 | spu_timer_start. This is OK, since this can happen any time interrupts |
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84 | are disabled. We just schedule an immediate timeout in this case. */ |
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85 | if (__spu_timers_active) |
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86 | { |
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87 | __spu_timers_active->tmout -= elapsed; |
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88 | if (__spu_timers_active->tmout < 0) |
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89 | __spu_timers_active->tmout = 0; |
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90 | } |
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91 | } |
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92 | |
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93 | /* Add an allocated timer to the active list. The active list is sorted by |
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94 | timeout value. The timer at the head of the list is the timer that will |
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95 | expire next. The rest of the timers have a timeout value that is relative |
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96 | to the timer ahead of it on the list. This relative value is determined |
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97 | here, when the timer is added to the active list. When its position in the |
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98 | list is found, the timer's timeout value is set to its interval minus the |
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99 | sum of all the timeout values ahead of it. The timeout value for the timer |
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100 | following the newly added timer is then adjusted to a new relative value. If |
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101 | the newly added timer is at the head of the list, the decrementer is reset. |
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102 | This function is called by SLIH to restart multiple timers (reset == 0) or |
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103 | by spu_timer_start() to start a single timer (reset == 1). */ |
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104 | void |
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105 | __spu_timer_start (int id, int reset) |
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106 | { |
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107 | spu_timer_t *t; |
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108 | spu_timer_t **pn; |
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109 | spu_timer_t *start = &__spu_timers[id]; |
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110 | unsigned tmout_time = 0; |
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111 | unsigned my_intvl = start->intvl; |
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112 | unsigned was_enabled = spu_readch (SPU_RdMachStat) & 0x1; |
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113 | |
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114 | spu_idisable (); |
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115 | |
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116 | t = __spu_timers_active; |
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117 | pn = &__spu_timers_active; |
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118 | |
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119 | /* If the active list is empty, just add the timer with the timeout set to |
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120 | the interval. Otherwise find the place in the list for the timer, setting |
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121 | its timeout to its interval minus the sum of timeouts ahead of it. */ |
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122 | start->state = SPU_TIMER_ACTIVE; |
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123 | if (__likely (!t)) |
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124 | { |
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125 | __spu_timers_active = start; |
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126 | start->next = NULL; |
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127 | start->tmout = my_intvl; |
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128 | } |
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129 | else |
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130 | { |
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131 | |
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132 | /* Update swtb and timeout val of the next timer, so all times are |
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133 | relative to now. */ |
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134 | if (reset) |
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135 | __update_spu_tb_val (); |
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136 | |
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137 | while (t && (my_intvl >= (tmout_time + t->tmout))) |
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138 | { |
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139 | tmout_time += t->tmout; |
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140 | pn = &t->next;; |
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141 | t = t->next; |
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142 | } |
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143 | start->next = t; |
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144 | start->tmout = my_intvl - tmout_time; |
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145 | *pn = start; |
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146 | |
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147 | /* Adjust timeout for timer after us. */ |
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148 | if (t) |
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149 | t->tmout -= start->tmout; |
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150 | } |
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151 | |
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152 | if (reset && (__spu_timers_active == start)) |
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153 | __reset_spu_decr (__spu_timers_active->tmout); |
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154 | |
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155 | if (__unlikely (was_enabled)) |
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156 | spu_ienable (); |
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157 | } |
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158 | |
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159 | /* SLIH for decrementer. Manages software timebase and timers. |
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160 | Called by SPU FLIH. Assumes decrementer is still running |
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161 | (event not yet acknowledeged). */ |
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162 | unsigned int |
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163 | spu_clock_slih (unsigned status) |
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164 | { |
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165 | int decr_reset_val; |
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166 | spu_timer_t *active, *handled; |
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167 | unsigned was_enabled = spu_readch (SPU_RdMachStat) & 0x1; |
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168 | |
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169 | status &= ~MFC_DECREMENTER_EVENT; |
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170 | |
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171 | spu_idisable (); |
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172 | |
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173 | /* The decrementer has now expired. The decrementer event was acknowledged |
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174 | in the FLIH but not disabled. The decrementer will continue to run while |
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175 | we're running the clock/timer handler. The software clock keeps running, |
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176 | and accounts for all the time spent running handlers. Add the current |
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177 | timeout to the software timebase and set the timeout to DECR_MAX. This |
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178 | allows the "clock read" code to continue to work while we're in here, and |
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179 | gives us the most possible time to finish before another underflow. */ |
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180 | __spu_tb_val += __spu_tb_timeout; |
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181 | __spu_tb_timeout = DECR_MAX; |
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182 | |
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183 | /* For all timers that have the current timeout value, move them from the |
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184 | active list to the handled list and call their handlers. Note that the |
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185 | handled/stopped lists may be manipulated by the handlers if they wish to |
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186 | stop/free the timers. Note that only the first expired timer will reflect |
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187 | the real timeout value; the rest of the timers that had the same timeout |
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188 | value will have a relative value of zero. */ |
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189 | if (__spu_timers_active) |
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190 | { |
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191 | __spu_timers_active->tmout = 0; |
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192 | while ((active = __spu_timers_active) |
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193 | && (active->tmout <= TIMER_INTERVAL_WINDOW)) |
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194 | { |
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195 | __spu_timers_active = active->next; |
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196 | active->next = __spu_timers_handled; |
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197 | __spu_timers_handled = active; |
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198 | active->state = SPU_TIMER_HANDLED; |
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199 | (*active->func) (active->id); |
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200 | } |
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201 | } |
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202 | |
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203 | /* put the handled timers back on the list and restart decrementer. */ |
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204 | while ((handled = __spu_timers_handled) != NULL) |
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205 | { |
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206 | __spu_timers_handled = handled->next; |
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207 | __spu_timer_start (handled->id, 0); |
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208 | } |
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209 | |
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210 | /* Reset the decrementer before returning. If we have any active timers, we |
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211 | set it to the timeout value for the timer at the head of the list, else |
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212 | the default clock value. */ |
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213 | decr_reset_val = __spu_timers_active ? __spu_timers_active->tmout : CLOCK_START_VALUE; |
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214 | |
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215 | __reset_spu_decr (decr_reset_val); |
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216 | |
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217 | if (__likely (was_enabled)) |
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218 | spu_ienable (); |
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219 | |
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220 | return status; |
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221 | } |
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