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  1. /*
  2.  * Copyright (C) 2001-2004 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @defgroup others Others
  30.  * @ingroup kernel
  31.  * @{
  32.  * @}
  33.  */
  34.  
  35.  /** @addtogroup generic generic   
  36.  * @{
  37.  */
  38.  
  39. /**
  40.  * @file
  41.  * @brief   High-level clock interrupt handler.
  42.  *
  43.  * This file contains the clock() function which is the source
  44.  * of preemption. It is also responsible for executing expired
  45.  * timeouts.
  46.  */
  47.  
  48. #include <time/clock.h>
  49. #include <time/timeout.h>
  50. #include <arch/types.h>
  51. #include <config.h>
  52. #include <synch/spinlock.h>
  53. #include <synch/waitq.h>
  54. #include <func.h>
  55. #include <proc/scheduler.h>
  56. #include <cpu.h>
  57. #include <arch.h>
  58. #include <adt/list.h>
  59. #include <atomic.h>
  60. #include <proc/thread.h>
  61. #include <sysinfo/sysinfo.h>
  62. #include <arch/barrier.h>
  63.  
  64. /* Pointers to public variables with time */
  65. struct ptime {
  66.     __native seconds1;
  67.     __native useconds;
  68.     __native seconds2;
  69. };
  70. struct ptime *public_time;
  71. /* Variable holding fragment of second, so that we would update
  72.  * seconds correctly
  73.  */
  74. static __native secfrag = 0;
  75.  
  76. /** Initialize realtime clock counter
  77.  *
  78.  * The applications (and sometimes kernel) need to access accurate
  79.  * information about realtime data. We allocate 1 page with these
  80.  * data and update it periodically.
  81.  *
  82.  *
  83.  */
  84. void clock_counter_init(void)
  85. {
  86.     void *faddr;
  87.  
  88.     faddr = (void *)PFN2ADDR(frame_alloc(0, FRAME_ATOMIC));
  89.     if (!faddr)
  90.         panic("Cannot allocate page for clock");
  91.    
  92.     public_time = (struct ptime *)PA2KA(faddr);
  93.  
  94.         /* TODO: We would need some arch dependent settings here */
  95.     public_time->seconds1 = 0;
  96.     public_time->seconds2 = 0;
  97.     public_time->useconds = 0;
  98.  
  99.     sysinfo_set_item_val("clock.faddr", NULL, (__native)faddr);
  100. }
  101.  
  102.  
  103. /** Update public counters
  104.  *
  105.  * Update it only on first processor
  106.  * TODO: Do we really need so many write barriers?
  107.  */
  108. static void clock_update_counters(void)
  109. {
  110.     if (CPU->id == 0) {
  111.         secfrag += 1000000/HZ;
  112.         if (secfrag >= 1000000) {
  113.             secfrag -= 1000000;
  114.             public_time->seconds1++;
  115.             write_barrier();
  116.             public_time->useconds = secfrag;
  117.             write_barrier();
  118.             public_time->seconds2 = public_time->seconds1;
  119.         } else
  120.             public_time->useconds += 1000000/HZ;
  121.     }
  122. }
  123.  
  124. /** Clock routine
  125.  *
  126.  * Clock routine executed from clock interrupt handler
  127.  * (assuming interrupts_disable()'d). Runs expired timeouts
  128.  * and preemptive scheduling.
  129.  *
  130.  */
  131. void clock(void)
  132. {
  133.     link_t *l;
  134.     timeout_t *h;
  135.     timeout_handler_t f;
  136.     void *arg;
  137.     count_t missed_clock_ticks = CPU->missed_clock_ticks;
  138.     int i;
  139.  
  140.     /*
  141.      * To avoid lock ordering problems,
  142.      * run all expired timeouts as you visit them.
  143.      */
  144.     for (i = 0; i <= missed_clock_ticks; i++) {
  145.         clock_update_counters();
  146.         spinlock_lock(&CPU->timeoutlock);
  147.         while ((l = CPU->timeout_active_head.next) != &CPU->timeout_active_head) {
  148.             h = list_get_instance(l, timeout_t, link);
  149.             spinlock_lock(&h->lock);
  150.             if (h->ticks-- != 0) {
  151.                 spinlock_unlock(&h->lock);
  152.                 break;
  153.             }
  154.             list_remove(l);
  155.             f = h->handler;
  156.             arg = h->arg;
  157.             timeout_reinitialize(h);
  158.             spinlock_unlock(&h->lock); 
  159.             spinlock_unlock(&CPU->timeoutlock);
  160.  
  161.             f(arg);
  162.  
  163.             spinlock_lock(&CPU->timeoutlock);
  164.         }
  165.         spinlock_unlock(&CPU->timeoutlock);
  166.     }
  167.     CPU->missed_clock_ticks = 0;
  168.  
  169.     /*
  170.      * Do CPU usage accounting and find out whether to preempt THREAD.
  171.      */
  172.  
  173.     if (THREAD) {
  174.         __u64 ticks;
  175.        
  176.         spinlock_lock(&CPU->lock);
  177.         CPU->needs_relink += 1 + missed_clock_ticks;
  178.         spinlock_unlock(&CPU->lock);   
  179.    
  180.         spinlock_lock(&THREAD->lock);
  181.         if ((ticks = THREAD->ticks)) {
  182.             if (ticks >= 1 + missed_clock_ticks)
  183.                 THREAD->ticks -= 1 + missed_clock_ticks;
  184.             else
  185.                 THREAD->ticks = 0;
  186.         }
  187.         spinlock_unlock(&THREAD->lock);
  188.        
  189.         if (!ticks && !PREEMPTION_DISABLED) {
  190.             scheduler();
  191.         }
  192.     }
  193.  
  194. }
  195.  
  196.  /** @}
  197.  */
  198.  
  199.