kernel/fiasco/src/kern/ia32/timer-apic.cpp

   1 IMPLEMENTATION [apic_timer]:
   2
   3 #include <cstdio>
   4
   5 #include "apic.h"
   6 #include "config.h"
   7 #include "cpu.h"
   8 #include "logdefs.h"
   9 #include "pit.h"
  10 #include "std_macros.h"
  11
  12 // no IRQ line for the LAPIC
  13 PUBLIC static inline int Timer::irq() { return -1; }
  14
  15 IMPLEMENT
  16 void
  17 Timer::init(Cpu_number)
  18 {
  19   Apic::timer_assign_irq_vector(Config::Apic_timer_vector);
  20
  21   if (Config::Scheduler_one_shot)
  22     {
  23       Apic::timer_set_one_shot();
  24       Apic::timer_reg_write(0xffffffff);
  25     }
  26   else
  27     {
  28       Apic::timer_set_periodic();
  29       Apic::timer_reg_write(Apic::us_to_apic(Config::Scheduler_granularity));
  30     }
  31
  32   // make sure that PIT does pull its interrupt line
  33   Pit::done();
  34
  35   if (!Config::Scheduler_one_shot)
  36     // from now we can save energy in getchar()
  37     Config::getchar_does_hlt_works_ok = false && Config::hlt_works_ok;
  38
  39   printf ("Using the Local APIC timer on vector %x (%s Mode) for scheduling\n",
  40           Config::Apic_timer_vector,
  41           Config::Scheduler_one_shot ? "One-Shot" : "Periodic");
  42 }
  43
  44 PUBLIC static inline
  45 void
  46 Timer::acknowledge()
  47 {}
  48
  49 static
  50 void
  51 Timer::update_one_shot(Unsigned64 wakeup)
  52 {
  53   Unsigned32 apic;
  54   Unsigned64 now = Kip::k()->clock;
  55   if (EXPECT_FALSE (wakeup <= now))
  56     // already expired
  57     apic = 1;
  58   else
  59     {
  60       Unsigned64 delta = wakeup - now;
  61       if (delta < Config::One_shot_min_interval_us)
  62         apic = Apic::us_to_apic(Config::One_shot_min_interval_us);
  63       else if (delta > Config::One_shot_max_interval_us)
  64         apic = Apic::us_to_apic(Config::One_shot_max_interval_us);
  65       else
  66         apic = Apic::us_to_apic(delta);
  67
  68       if (EXPECT_FALSE (apic < 1))
  69         // timeout too small
  70         apic = 1;
  71     }
  72
  73   Apic::timer_reg_write(apic);
  74 }
  75
  76 IMPLEMENT inline
  77 void
  78 Timer::update_timer(Unsigned64 wakeup)
  79 {
  80   if (Config::Scheduler_one_shot)
  81     update_one_shot(wakeup);
  82 }