cpu/arm926ejs/versatile/timer.c

   1 /*
   2  * (C) Copyright 2003
   3  * Texas Instruments <www.ti.com>
   4  *
   5  * (C) Copyright 2002
   6  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
   7  * Marius Groeger <mgroeger@sysgo.de>
   8  *
   9  * (C) Copyright 2002
  10  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
  11  * Alex Zuepke <azu@sysgo.de>
  12  *
  13  * (C) Copyright 2002-2004
  14  * Gary Jennejohn, DENX Software Engineering, <gj@denx.de>
  15  *
  16  * (C) Copyright 2004
  17  * Philippe Robin, ARM Ltd. <philippe.robin@arm.com>
  18  *
  19  * See file CREDITS for list of people who contributed to this
  20  * project.
  21  *
  22  * This program is free software; you can redistribute it and/or
  23  * modify it under the terms of the GNU General Public License as
  24  * published by the Free Software Foundation; either version 2 of
  25  * the License, or (at your option) any later version.
  26  *
  27  * This program is distributed in the hope that it will be useful,
  28  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  29  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  30  * GNU General Public License for more details.
  31  *
  32  * You should have received a copy of the GNU General Public License
  33  * along with this program; if not, write to the Free Software
  34  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  35  * MA 02111-1307 USA
  36  */
  37
  38 #include <common.h>
  39 #include <arm926ejs.h>
  40
  41 #define TIMER_LOAD_VAL 0xffffffff
  42
  43 /* macro to read the 32 bit timer */
  44 #define READ_TIMER (*(volatile ulong *)(CFG_TIMERBASE+4))
  45
  46 static ulong timestamp;
  47 static ulong lastdec;
  48
  49 /* nothing really to do with interrupts, just starts up a counter. */
  50 int timer_init (void)
  51 {
  52         *(volatile ulong *)(CFG_TIMERBASE + 0) = CFG_TIMER_RELOAD;      /* TimerLoad */
  53         *(volatile ulong *)(CFG_TIMERBASE + 4) = CFG_TIMER_RELOAD;      /* TimerValue */
  54         *(volatile ulong *)(CFG_TIMERBASE + 8) = 0x8C;
  55
  56         /* init the timestamp and lastdec value */
  57         reset_timer_masked();
  58
  59         return 0;
  60 }
  61
  62 /*
  63  * timer without interrupts
  64  */
  65
  66 void reset_timer (void)
  67 {
  68         reset_timer_masked ();
  69 }
  70
  71 ulong get_timer (ulong base)
  72 {
  73         return get_timer_masked () - base;
  74 }
  75
  76 void set_timer (ulong t)
  77 {
  78         timestamp = t;
  79 }
  80
  81 /* delay x useconds AND perserve advance timstamp value */
  82 void udelay (unsigned long usec)
  83 {
  84         ulong tmo, tmp;
  85
  86         if(usec >= 1000){               /* if "big" number, spread normalization to seconds */
  87                 tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
  88                 tmo *= CFG_HZ;          /* find number of "ticks" to wait to achieve target */
  89                 tmo /= 1000;            /* finish normalize. */
  90         }else{                          /* else small number, don't kill it prior to HZ multiply */
  91                 tmo = usec * CFG_HZ;
  92                 tmo /= (1000*1000);
  93         }
  94
  95         tmp = get_timer (0);            /* get current timestamp */
  96         if( (tmo + tmp + 1) < tmp )     /* if setting this fordward will roll time stamp */
  97                 reset_timer_masked ();  /* reset "advancing" timestamp to 0, set lastdec value */
  98         else
  99                 tmo += tmp;             /* else, set advancing stamp wake up time */
 100
 101         while (get_timer_masked () < tmo)/* loop till event */
 102                 /*NOP*/;
 103 }
 104
 105 void reset_timer_masked (void)
 106 {
 107         /* reset time */
 108         lastdec = READ_TIMER;  /* capure current decrementer value time */
 109         timestamp = 0;         /* start "advancing" time stamp from 0 */
 110 }
 111
 112 ulong get_timer_masked (void)
 113 {
 114         ulong now = READ_TIMER;         /* current tick value */
 115
 116         if (lastdec >= now) {           /* normal mode (non roll) */
 117                 /* normal mode */
 118                 timestamp += lastdec - now; /* move stamp fordward with absoulte diff ticks */
 119         } else {                        /* we have overflow of the count down timer */
 120                 /* nts = ts + ld + (TLV - now)
 121                  * ts=old stamp, ld=time that passed before passing through -1
 122                  * (TLV-now) amount of time after passing though -1
 123                  * nts = new "advancing time stamp"...it could also roll and cause problems.
 124                  */
 125                 timestamp += lastdec + TIMER_LOAD_VAL - now;
 126         }
 127         lastdec = now;
 128
 129         return timestamp;
 130 }
 131
 132 /* waits specified delay value and resets timestamp */
 133 void udelay_masked (unsigned long usec)
 134 {
 135         ulong tmo;
 136         ulong endtime;
 137         signed long diff;
 138
 139         if (usec >= 1000) {             /* if "big" number, spread normalization to seconds */
 140                 tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
 141                 tmo *= CFG_HZ;          /* find number of "ticks" to wait to achieve target */
 142                 tmo /= 1000;            /* finish normalize. */
 143         } else {                        /* else small number, don't kill it prior to HZ multiply */
 144                 tmo = usec * CFG_HZ;
 145                 tmo /= (1000*1000);
 146         }
 147
 148         endtime = get_timer_masked () + tmo;
 149
 150         do {
 151                 ulong now = get_timer_masked ();
 152                 diff = endtime - now;
 153         } while (diff >= 0);
 154 }
 155
 156 /*
 157  * This function is derived from PowerPC code (read timebase as long long).
 158  * On ARM it just returns the timer value.
 159  */
 160 unsigned long long get_ticks(void)
 161 {
 162         return get_timer(0);
 163 }
 164
 165 /*
 166  * This function is derived from PowerPC code (timebase clock frequency).
 167  * On ARM it returns the number of timer ticks per second.
 168  */
 169 ulong get_tbclk (void)
 170 {
 171         ulong tbclk;
 172
 173         tbclk = CFG_HZ;
 174         return tbclk;
 175 }