arch/arm/cpu/s3c44b0/timer.c

   1 /*
   2  * (C) Copyright 2004
   3  * DAVE Srl
   4  * http://www.dave-tech.it
   5  * http://www.wawnet.biz
   6  * mailto:info@wawnet.biz
   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 <asm/hardware.h>
  29
  30 /* we always count down the max. */
  31 #define TIMER_LOAD_VAL 0xffff
  32
  33 /* macro to read the 16 bit timer */
  34 #define READ_TIMER (TCNTO1 & 0xffff)
  35
  36 #ifdef CONFIG_USE_IRQ
  37 #error CONFIG_USE_IRQ NOT supported
  38 #endif
  39
  40 static ulong timestamp;
  41 static ulong lastdec;
  42
  43 int timer_init (void)
  44 {
  45         TCFG0 = 0x000000E9;
  46         TCFG1 = 0x00000004;
  47         TCON = 0x00000900;
  48         TCNTB1 = TIMER_LOAD_VAL;
  49         TCMPB1 = 0;
  50         TCON = 0x00000B00;
  51         TCON = 0x00000900;
  52
  53
  54         lastdec = TCNTB1 = TIMER_LOAD_VAL;
  55         timestamp = 0;
  56         return 0;
  57 }
  58
  59 /*
  60  * timer without interrupts
  61  */
  62 ulong get_timer (ulong base)
  63 {
  64         return get_timer_masked () - base;
  65 }
  66
  67 void __udelay (unsigned long usec)
  68 {
  69         ulong tmo;
  70
  71         tmo = usec / 1000;
  72         tmo *= CONFIG_SYS_HZ;
  73         tmo /= 8;
  74
  75         tmo += get_timer (0);
  76
  77         while (get_timer_masked () < tmo)
  78                 /*NOP*/;
  79 }
  80
  81 ulong get_timer_masked (void)
  82 {
  83         ulong now = READ_TIMER;
  84
  85         if (lastdec >= now) {
  86                 /* normal mode */
  87                 timestamp += lastdec - now;
  88         } else {
  89                 /* we have an overflow ... */
  90                 timestamp += lastdec + TIMER_LOAD_VAL - now;
  91         }
  92         lastdec = now;
  93
  94         return timestamp;
  95 }
  96
  97 void udelay_masked (unsigned long usec)
  98 {
  99         ulong tmo;
 100         ulong endtime;
 101         signed long diff;
 102
 103         if (usec >= 1000) {
 104                 tmo = usec / 1000;
 105                 tmo *= CONFIG_SYS_HZ;
 106                 tmo /= 8;
 107         } else {
 108                 tmo = usec * CONFIG_SYS_HZ;
 109                 tmo /= (1000*8);
 110         }
 111
 112         endtime = get_timer(0) + tmo;
 113
 114         do {
 115                 ulong now = get_timer_masked ();
 116                 diff = endtime - now;
 117         } while (diff >= 0);
 118 }