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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. /** @addtogroup ia64   
  30.  * @{
  31.  */
  32. /** @file
  33.  */
  34.  
  35. /** Interval Timer driver. */
  36.  
  37. #include <arch/drivers/it.h>
  38. #include <arch/interrupt.h>
  39. #include <arch/register.h>
  40. #include <arch/asm.h>
  41. #include <arch/barrier.h>
  42. #include <time/clock.h>
  43. #include <ddi/irq.h>
  44. #include <ddi/device.h>
  45. #include <arch.h>
  46.  
  47. #define IT_SERVICE_CLOCKS 64
  48.  
  49. static irq_t it_irq;
  50.  
  51. static irq_ownership_t it_claim(void);
  52. static void it_interrupt(irq_t *irq, void *arg, ...);
  53.  
  54. /** Initialize Interval Timer. */
  55. void it_init(void)
  56. {
  57.     cr_itv_t itv;
  58.    
  59.     if(config.cpu_active==1)
  60.     {
  61.         irq_initialize(&it_irq);
  62.         it_irq.inr = INTERRUPT_TIMER;
  63.         it_irq.devno = device_assign_devno();
  64.         it_irq.claim = it_claim;
  65.         it_irq.handler = it_interrupt;
  66.         irq_register(&it_irq);
  67.     }
  68.    
  69.     /* initialize Interval Timer external interrupt vector */
  70.     itv.value = itv_read();
  71.     itv.vector = INTERRUPT_TIMER;
  72.     itv.m = 0;
  73.     itv_write(itv.value);
  74.  
  75.     /* set Interval Timer Counter to zero */
  76.     itc_write(0);
  77.    
  78.     /* generate first Interval Timer interrupt in IT_DELTA ticks */
  79.     itm_write(IT_DELTA);
  80.  
  81.     /* propagate changes */
  82.     srlz_d();
  83. }
  84.  
  85. /** Always claim ownership for this IRQ.
  86.  *
  87.  * Other devices are responsible to avoid using INR 0.
  88.  *
  89.  * @return Always IRQ_ACCEPT.
  90.  */
  91. irq_ownership_t it_claim(void)
  92. {
  93.     return IRQ_ACCEPT;
  94. }
  95.  
  96. /** Process Interval Timer interrupt. */
  97. void it_interrupt(irq_t *irq, void *arg, ...)
  98. {
  99.     int64_t c;
  100.     int64_t m;
  101.    
  102.     eoi_write(EOI);
  103.    
  104.     m = itm_read();
  105.    
  106.     while (1) {
  107.         c = itc_read();
  108.         c += IT_SERVICE_CLOCKS;
  109.  
  110.         m += IT_DELTA;
  111.         if (m - c < 0)
  112.             CPU->missed_clock_ticks++;
  113.         else
  114.             break;
  115.     }
  116.    
  117.     itm_write(m);
  118.     srlz_d();               /* propagate changes */
  119.  
  120.     /*
  121.      * We are holding a lock which prevents preemption.
  122.      * Release the lock, call clock() and reacquire the lock again.
  123.      */
  124.     spinlock_unlock(&irq->lock);   
  125.     clock();
  126.     spinlock_lock(&irq->lock);
  127. }
  128.  
  129. /** @}
  130.  */
  131.