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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. /** @addtogroup time
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file
  35.  * @brief   High-level clock interrupt handler.
  36.  *
  37.  * This file contains the clock() function which is the source
  38.  * of preemption. It is also responsible for executing expired
  39.  * timeouts.
  40.  */
  41.  
  42. #include <time/clock.h>
  43. #include <time/timeout.h>
  44. #include <arch/types.h>
  45. #include <config.h>
  46. #include <synch/spinlock.h>
  47. #include <synch/waitq.h>
  48. #include <func.h>
  49. #include <proc/scheduler.h>
  50. #include <cpu.h>
  51. #include <arch.h>
  52. #include <adt/list.h>
  53. #include <atomic.h>
  54. #include <proc/thread.h>
  55. #include <sysinfo/sysinfo.h>
  56. #include <arch/barrier.h>
  57.  
  58. /* Pointers to public variables with time */
  59. struct ptime {
  60.     unative_t seconds1;
  61.     unative_t useconds;
  62.     unative_t seconds2;
  63. };
  64. struct ptime *public_time;
  65. /* Variable holding fragment of second, so that we would update
  66.  * seconds correctly
  67.  */
  68. static unative_t secfrag = 0;
  69.  
  70. /** Initialize realtime clock counter
  71.  *
  72.  * The applications (and sometimes kernel) need to access accurate
  73.  * information about realtime data. We allocate 1 page with these
  74.  * data and update it periodically.
  75.  *
  76.  *
  77.  */
  78. void clock_counter_init(void)
  79. {
  80.     void *faddr;
  81.  
  82.     faddr = frame_alloc(0, FRAME_ATOMIC);
  83.     if (!faddr)
  84.         panic("Cannot allocate page for clock");
  85.    
  86.     public_time = (struct ptime *)PA2KA(faddr);
  87.  
  88.         /* TODO: We would need some arch dependent settings here */
  89.     public_time->seconds1 = 0;
  90.     public_time->seconds2 = 0;
  91.     public_time->useconds = 0;
  92.  
  93.     sysinfo_set_item_val("clock.faddr", NULL, (unative_t)faddr);
  94. }
  95.  
  96.  
  97. /** Update public counters
  98.  *
  99.  * Update it only on first processor
  100.  * TODO: Do we really need so many write barriers?
  101.  */
  102. static void clock_update_counters(void)
  103. {
  104.     if (CPU->id == 0) {
  105.         secfrag += 1000000/HZ;
  106.         if (secfrag >= 1000000) {
  107.             secfrag -= 1000000;
  108.             public_time->seconds1++;
  109.             write_barrier();
  110.             public_time->useconds = secfrag;
  111.             write_barrier();
  112.             public_time->seconds2 = public_time->seconds1;
  113.         } else
  114.             public_time->useconds += 1000000/HZ;
  115.     }
  116. }
  117.  
  118. /** Clock routine
  119.  *
  120.  * Clock routine executed from clock interrupt handler
  121.  * (assuming interrupts_disable()'d). Runs expired timeouts
  122.  * and preemptive scheduling.
  123.  *
  124.  */
  125. void clock(void)
  126. {
  127.     link_t *l;
  128.     timeout_t *h;
  129.     timeout_handler_t f;
  130.     void *arg;
  131.     count_t missed_clock_ticks = CPU->missed_clock_ticks;
  132.     int i;
  133.  
  134.     /*
  135.      * To avoid lock ordering problems,
  136.      * run all expired timeouts as you visit them.
  137.      */
  138.     for (i = 0; i <= missed_clock_ticks; i++) {
  139.         clock_update_counters();
  140.         spinlock_lock(&CPU->timeoutlock);
  141.         while ((l = CPU->timeout_active_head.next) != &CPU->timeout_active_head) {
  142.             h = list_get_instance(l, timeout_t, link);
  143.             spinlock_lock(&h->lock);
  144.             if (h->ticks-- != 0) {
  145.                 spinlock_unlock(&h->lock);
  146.                 break;
  147.             }
  148.             list_remove(l);
  149.             f = h->handler;
  150.             arg = h->arg;
  151.             timeout_reinitialize(h);
  152.             spinlock_unlock(&h->lock); 
  153.             spinlock_unlock(&CPU->timeoutlock);
  154.  
  155.             f(arg);
  156.  
  157.             spinlock_lock(&CPU->timeoutlock);
  158.         }
  159.         spinlock_unlock(&CPU->timeoutlock);
  160.     }
  161.     CPU->missed_clock_ticks = 0;
  162.  
  163.     /*
  164.      * Do CPU usage accounting and find out whether to preempt THREAD.
  165.      */
  166.  
  167.     if (THREAD) {
  168.         uint64_t ticks;
  169.        
  170.         spinlock_lock(&CPU->lock);
  171.         CPU->needs_relink += 1 + missed_clock_ticks;
  172.         spinlock_unlock(&CPU->lock);   
  173.    
  174.         spinlock_lock(&THREAD->lock);
  175.         if ((ticks = THREAD->ticks)) {
  176.             if (ticks >= 1 + missed_clock_ticks)
  177.                 THREAD->ticks -= 1 + missed_clock_ticks;
  178.             else
  179.                 THREAD->ticks = 0;
  180.         }
  181.         spinlock_unlock(&THREAD->lock);
  182.        
  183.         if (!ticks && !PREEMPTION_DISABLED) {
  184.             scheduler();
  185.         }
  186.     }
  187.  
  188. }
  189.  
  190. /** @}
  191.  */
  192.