LXR uboot/lib_i386/timer.c

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