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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. #include <mm/frame.h>
  58. #include <ddi/ddi.h>
  59.  
  60. /** Physical memory area of the real time clock. */
  61. static parea_t clock_parea;
  62.  
  63. /* Pointers to public variables with time */
  64. struct ptime {
  65.     unative_t seconds1;
  66.     unative_t useconds;
  67.     unative_t seconds2;
  68. };
  69. struct ptime *public_time;
  70. /* Variable holding fragment of second, so that we would update
  71.  * seconds correctly
  72.  */
  73. static unative_t secfrag = 0;
  74.  
  75. /** Initialize realtime clock counter
  76.  *
  77.  * The applications (and sometimes kernel) need to access accurate
  78.  * information about realtime data. We allocate 1 page with these
  79.  * data and update it periodically.
  80.  */
  81. void clock_counter_init(void)
  82. {
  83.     void *faddr;
  84.  
  85.     faddr = frame_alloc(ONE_FRAME, FRAME_ATOMIC);
  86.     if (!faddr)
  87.         panic("Cannot allocate page for clock");
  88.    
  89.     public_time = (struct ptime *) PA2KA(faddr);
  90.  
  91.         /* TODO: We would need some arch dependent settings here */
  92.     public_time->seconds1 = 0;
  93.     public_time->seconds2 = 0;
  94.     public_time->useconds = 0;
  95.  
  96.     clock_parea.pbase = (uintptr_t) faddr;
  97.     clock_parea.vbase = (uintptr_t) public_time;
  98.     clock_parea.frames = 1;
  99.     clock_parea.cacheable = true;
  100.     ddi_parea_register(&clock_parea);
  101.  
  102.     /*
  103.      * Prepare information for the userspace so that it can successfully
  104.      * physmem_map() the clock_parea.
  105.      */
  106.     sysinfo_set_item_val("clock.cacheable", NULL, (unative_t) true);
  107.     sysinfo_set_item_val("clock.faddr", NULL, (unative_t) faddr);
  108. }
  109.  
  110.  
  111. /** Update public counters
  112.  *
  113.  * Update it only on first processor
  114.  * TODO: Do we really need so many write barriers?
  115.  */
  116. static void clock_update_counters(void)
  117. {
  118.     if (CPU->id == 0) {
  119.         secfrag += 1000000/HZ;
  120.         if (secfrag >= 1000000) {
  121.             secfrag -= 1000000;
  122.             public_time->seconds1++;
  123.             write_barrier();
  124.             public_time->useconds = secfrag;
  125.             write_barrier();
  126.             public_time->seconds2 = public_time->seconds1;
  127.         } else
  128.             public_time->useconds += 1000000/HZ;
  129.     }
  130. }
  131.  
  132. /** Clock routine
  133.  *
  134.  * Clock routine executed from clock interrupt handler
  135.  * (assuming interrupts_disable()'d). Runs expired timeouts
  136.  * and preemptive scheduling.
  137.  *
  138.  */
  139. void clock(void)
  140. {
  141.     link_t *l;
  142.     timeout_t *h;
  143.     timeout_handler_t f;
  144.     void *arg;
  145.     count_t missed_clock_ticks = CPU->missed_clock_ticks;
  146.     int i;
  147.  
  148.     /*
  149.      * To avoid lock ordering problems,
  150.      * run all expired timeouts as you visit them.
  151.      */
  152.     for (i = 0; i <= missed_clock_ticks; i++) {
  153.         clock_update_counters();
  154.         spinlock_lock(&CPU->timeoutlock);
  155.         while ((l = CPU->timeout_active_head.next) != &CPU->timeout_active_head) {
  156.             h = list_get_instance(l, timeout_t, link);
  157.             spinlock_lock(&h->lock);
  158.             if (h->ticks-- != 0) {
  159.                 spinlock_unlock(&h->lock);
  160.                 break;
  161.             }
  162.             list_remove(l);
  163.             f = h->handler;
  164.             arg = h->arg;
  165.             timeout_reinitialize(h);
  166.             spinlock_unlock(&h->lock); 
  167.             spinlock_unlock(&CPU->timeoutlock);
  168.  
  169.             f(arg);
  170.  
  171.             spinlock_lock(&CPU->timeoutlock);
  172.         }
  173.         spinlock_unlock(&CPU->timeoutlock);
  174.     }
  175.     CPU->missed_clock_ticks = 0;
  176.  
  177.     /*
  178.      * Do CPU usage accounting and find out whether to preempt THREAD.
  179.      */
  180.  
  181.     if (THREAD) {
  182.         uint64_t ticks;
  183.        
  184.         spinlock_lock(&CPU->lock);
  185.         CPU->needs_relink += 1 + missed_clock_ticks;
  186.         spinlock_unlock(&CPU->lock);   
  187.    
  188.         spinlock_lock(&THREAD->lock);
  189.         if ((ticks = THREAD->ticks)) {
  190.             if (ticks >= 1 + missed_clock_ticks)
  191.                 THREAD->ticks -= 1 + missed_clock_ticks;
  192.             else
  193.                 THREAD->ticks = 0;
  194.         }
  195.         spinlock_unlock(&THREAD->lock);
  196.        
  197.         if (!ticks && !PREEMPTION_DISABLED) {
  198.             scheduler();
  199.         }
  200.     }
  201.  
  202. }
  203.  
  204. /** @}
  205.  */
  206.