lib_mips/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
  27 static 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
  36 int 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
  45 void reset_timer(void)
  46 {
  47         timestamp = 0;
  48         write_c0_compare(read_c0_count() + CYCLES_PER_JIFFY);
  49 }
  50
  51 ulong 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
  67 void set_timer(ulong t)
  68 {
  69         timestamp = t;
  70         write_c0_compare(read_c0_count() + CYCLES_PER_JIFFY);
  71 }
  72
  73 void __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  */
  86 unsigned 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  */
  95 ulong get_tbclk(void)
  96 {
  97         return CONFIG_SYS_HZ;
  98 }