cpu/arm926ejs/omap/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, <garyj@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 *)(CONFIG_SYS_TIMERBASE+8))
  45
  46 static ulong timestamp;
  47 static ulong lastdec;
  48
  49 int timer_init (void)
  50 {
  51         int32_t val;
  52
  53         /* Start the decrementer ticking down from 0xffffffff */
  54         *((int32_t *) (CONFIG_SYS_TIMERBASE + LOAD_TIM)) = TIMER_LOAD_VAL;
  55         val = MPUTIM_ST | MPUTIM_AR | MPUTIM_CLOCK_ENABLE | (CONFIG_SYS_PTV << MPUTIM_PTV_BIT);
  56         *((int32_t *) (CONFIG_SYS_TIMERBASE + CNTL_TIMER)) = val;
  57
  58         /* init the timestamp and lastdec value */
  59         reset_timer_masked();
  60
  61         return 0;
  62 }
  63
  64 /*
  65  * timer without interrupts
  66  */
  67
  68 void reset_timer (void)
  69 {
  70         reset_timer_masked ();
  71 }
  72
  73 ulong get_timer (ulong base)
  74 {
  75         return get_timer_masked () - base;
  76 }
  77
  78 void set_timer (ulong t)
  79 {
  80         timestamp = t;
  81 }
  82
  83 /* delay x useconds AND perserve advance timstamp value */
  84 void udelay (unsigned long usec)
  85 {
  86         ulong tmo, tmp;
  87
  88         if(usec >= 1000){               /* if "big" number, spread normalization to seconds */
  89                 tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
  90                 tmo *= CONFIG_SYS_HZ;           /* find number of "ticks" to wait to achieve target */
  91                 tmo /= 1000;            /* finish normalize. */
  92         }else{                          /* else small number, don't kill it prior to HZ multiply */
  93                 tmo = usec * CONFIG_SYS_HZ;
  94                 tmo /= (1000*1000);
  95         }
  96
  97         tmp = get_timer (0);            /* get current timestamp */
  98         if( (tmo + tmp + 1) < tmp )     /* if setting this fordward will roll time stamp */
  99                 reset_timer_masked ();  /* reset "advancing" timestamp to 0, set lastdec value */
 100         else
 101                 tmo += tmp;             /* else, set advancing stamp wake up time */
 102
 103         while (get_timer_masked () < tmo)/* loop till event */
 104                 /*NOP*/;
 105 }
 106
 107 void reset_timer_masked (void)
 108 {
 109         /* reset time */
 110         lastdec = READ_TIMER;  /* capure current decrementer value time */
 111         timestamp = 0;         /* start "advancing" time stamp from 0 */
 112 }
 113
 114 ulong get_timer_masked (void)
 115 {
 116         ulong now = READ_TIMER;         /* current tick value */
 117
 118         if (lastdec >= now) {           /* normal mode (non roll) */
 119                 /* normal mode */
 120                 timestamp += lastdec - now; /* move stamp fordward with absoulte diff ticks */
 121         } else {                        /* we have overflow of the count down timer */
 122                 /* nts = ts + ld + (TLV - now)
 123                  * ts=old stamp, ld=time that passed before passing through -1
 124                  * (TLV-now) amount of time after passing though -1
 125                  * nts = new "advancing time stamp"...it could also roll and cause problems.
 126                  */
 127                 timestamp += lastdec + TIMER_LOAD_VAL - now;
 128         }
 129         lastdec = now;
 130
 131         return timestamp;
 132 }
 133
 134 /* waits specified delay value and resets timestamp */
 135 void udelay_masked (unsigned long usec)
 136 {
 137         ulong tmo;
 138         ulong endtime;
 139         signed long diff;
 140
 141         if (usec >= 1000) {             /* if "big" number, spread normalization to seconds */
 142                 tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
 143                 tmo *= CONFIG_SYS_HZ;           /* find number of "ticks" to wait to achieve target */
 144                 tmo /= 1000;            /* finish normalize. */
 145         } else {                        /* else small number, don't kill it prior to HZ multiply */
 146                 tmo = usec * CONFIG_SYS_HZ;
 147                 tmo /= (1000*1000);
 148         }
 149
 150         endtime = get_timer_masked () + tmo;
 151
 152         do {
 153                 ulong now = get_timer_masked ();
 154                 diff = endtime - now;
 155         } while (diff >= 0);
 156 }
 157
 158 /*
 159  * This function is derived from PowerPC code (read timebase as long long).
 160  * On ARM it just returns the timer value.
 161  */
 162 unsigned long long get_ticks(void)
 163 {
 164         return get_timer(0);
 165 }
 166
 167 /*
 168  * This function is derived from PowerPC code (timebase clock frequency).
 169  * On ARM it returns the number of timer ticks per second.
 170  */
 171 ulong get_tbclk (void)
 172 {
 173         ulong tbclk;
 174
 175         tbclk = CONFIG_SYS_HZ;
 176         return tbclk;
 177 }