LXR uboot/arch/mips/lib/time.c

   1/*
   2 * (C) Copyright 2003
   3 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   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 <asm/mipsregs.h>
  26
  27static unsigned long timestamp;
  28
  29/* how many counter cycles in a jiffy */
  30#define CYCLES_PER_JIFFY        (CONFIG_SYS_MIPS_TIMER_FREQ + CONFIG_SYS_HZ / 2) / CONFIG_SYS_HZ
  31
  32/*
  33 * timer without interrupts
  34 */
  35
  36int timer_init(void)
  37{
  38        /* Set up the timer for the first expiration. */
  39        timestamp = 0;
  40        write_c0_compare(read_c0_count() + CYCLES_PER_JIFFY);
  41
  42        return 0;
  43}
  44
  45void reset_timer(void)
  46{
  47        timestamp = 0;
  48        write_c0_compare(read_c0_count() + CYCLES_PER_JIFFY);
  49}
  50
  51ulong get_timer(ulong base)
  52{
  53        unsigned int count;
  54        unsigned int expirelo = read_c0_compare();
  55
  56        /* Check to see if we have missed any timestamps. */
  57        count = read_c0_count();
  58        while ((count - expirelo) < 0x7fffffff) {
  59                expirelo += CYCLES_PER_JIFFY;
  60                timestamp++;
  61        }
  62        write_c0_compare(expirelo);
  63
  64        return (timestamp - base);
  65}
  66
  67void set_timer(ulong t)
  68{
  69        timestamp = t;
  70        write_c0_compare(read_c0_count() + CYCLES_PER_JIFFY);
  71}
  72
  73void __udelay(unsigned long usec)
  74{
  75        unsigned int tmo;
  76
  77        tmo = read_c0_count() + (usec * (CONFIG_SYS_MIPS_TIMER_FREQ / 1000000));
  78        while ((tmo - read_c0_count()) < 0x7fffffff)
  79                /*NOP*/;
  80}
  81
  82/*
  83 * This function is derived from PowerPC code (read timebase as long long).
  84 * On MIPS it just returns the timer value.
  85 */
  86unsigned long long get_ticks(void)
  87{
  88        return get_timer(0);
  89}
  90
  91/*
  92 * This function is derived from PowerPC code (timebase clock frequency).
  93 * On MIPS it returns the number of timer ticks per second.
  94 */
  95ulong get_tbclk(void)
  96{
  97        return CONFIG_SYS_HZ;
  98}
  99