rom/timer/timer_init.c

   1 /*
   2     Copyright © 1995-2011, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Timer startup and device commands, reference code
   6
   7     This code uses VBlank interrupt as a source for both units. This can be
   8     considered a reference code for building basic timer.device implementations,
   9     using a periodic timer. However, in real life you'll want better timing source
  10     than 50 Hz, so you'll likely replace this with your own code.
  11 */
  12
  13 /****************************************************************************************/
  14
  15 #include <exec/types.h>
  16 #include <exec/io.h>
  17 #include <exec/errors.h>
  18 #include <exec/devices.h>
  19 #include <exec/alerts.h>
  20 #include <exec/initializers.h>
  21 #include <devices/timer.h>
  22 #include <hardware/intbits.h>
  23
  24 #include <proto/exec.h>
  25 #include <proto/timer.h>
  26
  27 #include <aros/symbolsets.h>
  28 #include <aros/debug.h>
  29
  30 #include LC_LIBDEFS_FILE
  31
  32 #include "timer_macros.h"
  33
  34 /* exec.library VBlank interrupt handler  */
  35 static AROS_INTH1(VBlankInt, struct TimerBase *, TimerBase)
  36 {
  37     AROS_INTFUNC_INIT
  38
  39     /*
  40      * First increment the current time. No need to Disable() here as
  41      * there are no other interrupts that are allowed to interrupt us
  42      * that can do anything with this.
  43      */
  44     ADDTIME(&TimerBase->tb_CurrentTime, &TimerBase->tb_Platform.tb_VBlankTime);
  45     ADDTIME(&TimerBase->tb_Elapsed, &TimerBase->tb_Platform.tb_VBlankTime);
  46     TimerBase->tb_ticks_total++;
  47
  48     /*
  49      * Now go to handle requests.
  50      * We are called at rather low rate, so don't bother and process both units.
  51      */
  52     handleMicroHZ(TimerBase, SysBase);
  53     handleVBlank(TimerBase, SysBase);
  54
  55     return 0;
  56
  57     AROS_INTFUNC_EXIT
  58 }
  59
  60 /****************************************************************************************/
  61
  62 static int GM_UNIQUENAME(Init)(LIBBASETYPEPTR LIBBASE)
  63 {
  64     struct Interrupt *is;
  65
  66     /* If no frequency is set, assume 50Hz */
  67     if (SysBase->VBlankFrequency == 0)
  68         SysBase->VBlankFrequency = 50;
  69
  70     /*
  71      * Here we do no checks, we simply assume we have working VBlank interrupt,
  72      * from whatever source it is.
  73      */
  74
  75     LIBBASE->tb_eclock_rate = SysBase->VBlankFrequency;
  76     D(bug("[timer] Timer IRQ is %d, frequency is %u Hz\n", INTB_VERTB, LIBBASE->tb_eclock_rate));
  77
  78     /* Calculate timer period in us */
  79     LIBBASE->tb_Platform.tb_VBlankTime.tv_secs  = 0;
  80     LIBBASE->tb_Platform.tb_VBlankTime.tv_micro = 1000000 / LIBBASE->tb_eclock_rate;
  81
  82     D(bug("Timer period: %ld secs, %ld micros\n",
  83         LIBBASE->tb_Platform.tb_VBlankTime.tv_secs, LIBBASE->tb_Platform.tb_VBlankTime.tv_micro));
  84
  85     /* Start up the interrupt server */
  86     is = AllocMem(sizeof(struct Interrupt), MEMF_PUBLIC);
  87     if (is)
  88     {
  89         is->is_Node.ln_Pri = 0;
  90         is->is_Node.ln_Type = NT_INTERRUPT;
  91         is->is_Node.ln_Name = (STRPTR)MOD_NAME_STRING;
  92         is->is_Code = (VOID_FUNC)VBlankInt;
  93         is->is_Data = LIBBASE;
  94
  95         AddIntServer(INTB_VERTB, is);
  96         LIBBASE->tb_TimerIRQHandle = is;
  97
  98         return TRUE;
  99     }
 100
 101     return FALSE;
 102 }
 103
 104 /****************************************************************************************/
 105
 106 ADD2INITLIB(GM_UNIQUENAME(Init), 0)