cp/nucleus/ext.c

   1 /*
   2  * (C) Copyright 2007-2010  Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
   3  *
   4  * This file is released under the GPLv2.  See the COPYING file for more
   5  * details.
   6  */
   7
   8 #include <interrupt.h>
   9 #include <sched.h>
  10
  11 /*
  12  * This is the tick counter, it starts at 0 when we initialize the nucleus
  13  */
  14 volatile u64 ticks;
  15
  16 void set_timer(void)
  17 {
  18         u64 time = 1000 * 1000 * CLK_MICROSEC / HZ;
  19
  20         asm volatile(
  21                 "spt    %0\n"           /* set timer value */
  22         : /* output */
  23         : /* input */
  24           "m" (time)
  25         );
  26 }
  27
  28 void __ext_int_handler(void)
  29 {
  30         if (*EXT_INT_CODE == 0x1005) {
  31                 /*
  32                  * This is the timer, let's call the scheduler.
  33                  */
  34
  35                 ticks++;
  36
  37                 set_timer();
  38
  39                 /*
  40                  * No need to save the registers, the assembly stub that
  41                  * called this function already saved them at PSA_INT_GPR
  42                  */
  43                 if (!(ticks % SCHED_TICKS_PER_SLICE)) {
  44                         __schedule(EXT_INT_OLD_PSW, TASK_SLEEPING);
  45
  46                         /* unreachable */
  47                         BUG();
  48                 }
  49         }
  50 }
  51