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  1. /*
  2.  * Copyright (C) 2005 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. /** Interval Timer driver. */
  30.  
  31. #include <arch/drivers/it.h>
  32. #include <arch/ski/ski.h>
  33. #include <arch/interrupt.h>
  34. #include <arch/register.h>
  35. #include <arch/asm.h>
  36. #include <arch/barrier.h>
  37. #include <time/clock.h>
  38. #include <arch.h>
  39.  
  40.  
  41. #define IT_SERVICE_CLOCKS 64
  42.  
  43. /** Initialize Interval Timer. */
  44. void it_init(void)
  45. {
  46.     cr_itv_t itv;
  47.  
  48.     /* initialize Interval Timer external interrupt vector */
  49.     itv.value = itv_read();
  50.     itv.vector = INTERRUPT_TIMER;
  51.     itv.m = 0;
  52.     itv_write(itv.value);
  53.  
  54.     /* set Interval Timer Counter to zero */
  55.     itc_write(0);
  56.    
  57.     /* generate first Interval Timer interrupt in IT_DELTA ticks */
  58.     itm_write(IT_DELTA);
  59.  
  60.     /* propagate changes */
  61.     srlz_d();
  62. }
  63.  
  64.  
  65. /** Process Interval Timer interrupt. */
  66. void it_interrupt(void)
  67. {
  68.     __s64 c;
  69.     __s64 m;
  70.    
  71.     eoi_write(EOI);
  72.    
  73.     m=itm_read();
  74.    
  75.     while(1)
  76.     {
  77.    
  78.         c=itc_read();
  79.         c+=IT_SERVICE_CLOCKS;
  80.  
  81.         m+=IT_DELTA;
  82.         if(m-c<0)
  83.         {
  84.             CPU->missed_clock_ticks++;
  85.         }
  86.         else break;
  87.     }
  88.    
  89.     itm_write(m);
  90.     srlz_d();               /* propagate changes */
  91.    
  92.    
  93.    
  94.     clock();
  95.     poll_keyboard();
  96. }
  97.