arch/x86/lib/timer.c

   1 /*
   2  * (C) Copyright 2008,2009
   3  * Graeme Russ, <graeme.russ@gmail.com>
   4  *
   5  * (C) Copyright 2002
   6  * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
   7  *
   8  * See file CREDITS for list of people who contributed to this
   9  * project.
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License as
  13  * published by the Free Software Foundation; either version 2 of
  14  * the License, or (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  24  * MA 02111-1307 USA
  25  */
  26
  27 #include <common.h>
  28 #include <malloc.h>
  29 #include <asm/io.h>
  30 #include <asm/i8254.h>
  31 #include <asm/ibmpc.h>
  32
  33 struct timer_isr_function {
  34         struct timer_isr_function *next;
  35         timer_fnc_t *isr_func;
  36 };
  37
  38 static struct timer_isr_function *first_timer_isr = NULL;
  39 static volatile unsigned long system_ticks = 0;
  40
  41 /*
  42  * register_timer_isr() allows multiple architecture and board specific
  43  * functions to be called every millisecond. Keep the execution time of
  44  * each function as low as possible
  45  */
  46 int register_timer_isr (timer_fnc_t *isr_func)
  47 {
  48         struct timer_isr_function *new_func;
  49         struct timer_isr_function *temp;
  50         int flag;
  51
  52         new_func = malloc(sizeof(struct timer_isr_function));
  53
  54         if (new_func == NULL)
  55                 return 1;
  56
  57         new_func->isr_func = isr_func;
  58         new_func->next = NULL;
  59
  60         /*
  61          *  Don't allow timer interrupts while the
  62          *  linked list is being modified
  63          */
  64         flag = disable_interrupts ();
  65
  66         if (first_timer_isr == NULL) {
  67                 first_timer_isr = new_func;
  68         } else {
  69                 temp = first_timer_isr;
  70                 while (temp->next != NULL)
  71                         temp = temp->next;
  72                 temp->next = new_func;
  73         }
  74
  75         if (flag)
  76                 enable_interrupts ();
  77
  78         return 0;
  79 }
  80
  81 /*
  82  * timer_isr() MUST be the registered interrupt handler for
  83  */
  84 void timer_isr(void *unused)
  85 {
  86         struct timer_isr_function *temp = first_timer_isr;
  87
  88         system_ticks++;
  89
  90         /* Execute each registered function */
  91         while (temp != NULL) {
  92                 temp->isr_func ();
  93                 temp = temp->next;
  94         }
  95 }
  96
  97 void reset_timer (void)
  98 {
  99         system_ticks = 0;
 100 }
 101
 102 ulong get_timer (ulong base)
 103 {
 104         return (system_ticks - base);
 105 }
 106
 107 void set_timer (ulong t)
 108 {
 109         system_ticks = t;
 110 }