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
  40 #define TIMER_LOAD_VAL 0xffffffff
  41
  42 /* macro to read the 32 bit timer */
  43 #define READ_TIMER (*(volatile ulong *)(CONFIG_SYS_TIMERBASE+8))
  44
  45 static ulong timestamp;
  46 static ulong lastdec;
  47
  48 int timer_init (void)
  49 {
  50         int32_t val;
  51
  52         /* Start the decrementer ticking down from 0xffffffff */
  53         *((int32_t *) (CONFIG_SYS_TIMERBASE + LOAD_TIM)) = TIMER_LOAD_VAL;
  54         val = MPUTIM_ST | MPUTIM_AR | MPUTIM_CLOCK_ENABLE | (CONFIG_SYS_PTV << MPUTIM_PTV_BIT);
  55         *((int32_t *) (CONFIG_SYS_TIMERBASE + CNTL_TIMER)) = val;
  56
  57         /* init the timestamp and lastdec value */
  58         reset_timer_masked();
  59
  60         return 0;
  61 }
  62
  63 /*
  64  * timer without interrupts
  65  */
  66
  67 void reset_timer (void)
  68 {
  69         reset_timer_masked ();
  70 }
  71
  72 ulong get_timer (ulong base)
  73 {
  74         return get_timer_masked () - base;
  75 }
  76
  77 void set_timer (ulong t)
  78 {
  79         timestamp = t;
  80 }
  81
  82 /* delay x useconds AND perserve advance timstamp value */
  83 void __udelay (unsigned long usec)
  84 {
  85         ulong tmo, tmp;
  86
  87         if(usec >= 1000){               /* if "big" number, spread normalization to seconds */
  88                 tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
  89                 tmo *= CONFIG_SYS_HZ;           /* find number of "ticks" to wait to achieve target */
  90                 tmo /= 1000;            /* finish normalize. */
  91         }else{                          /* else small number, don't kill it prior to HZ multiply */
  92                 tmo = usec * CONFIG_SYS_HZ;
  93                 tmo /= (1000*1000);
  94         }
  95
  96         tmp = get_timer (0);            /* get current timestamp */
  97         if( (tmo + tmp + 1) < tmp )     /* if setting this fordward will roll time stamp */
  98                 reset_timer_masked ();  /* reset "advancing" timestamp to 0, set lastdec value */
  99         else
 100                 tmo += tmp;             /* else, set advancing stamp wake up time */
 101
 102         while (get_timer_masked () < tmo)/* loop till event */
 103                 /*NOP*/;
 104 }
 105
 106 void reset_timer_masked (void)
 107 {
 108         /* reset time */
 109         lastdec = READ_TIMER;  /* capure current decrementer value time */
 110         timestamp = 0;         /* start "advancing" time stamp from 0 */
 111 }
 112
 113 ulong get_timer_masked (void)
 114 {
 115         ulong now = READ_TIMER;         /* current tick value */
 116
 117         if (lastdec >= now) {           /* normal mode (non roll) */
 118                 /* normal mode */
 119                 timestamp += lastdec - now; /* move stamp fordward with absoulte diff ticks */
 120         } else {                        /* we have overflow of the count down timer */
 121                 /* nts = ts + ld + (TLV - now)
 122                  * ts=old stamp, ld=time that passed before passing through -1
 123                  * (TLV-now) amount of time after passing though -1
 124                  * nts = new "advancing time stamp"...it could also roll and cause problems.
 125                  */
 126                 timestamp += lastdec + TIMER_LOAD_VAL - now;
 127         }
 128         lastdec = now;
 129
 130         return timestamp;
 131 }
 132
 133 /* waits specified delay value and resets timestamp */
 134 void udelay_masked (unsigned long usec)
 135 {
 136         ulong tmo;
 137         ulong endtime;
 138         signed long diff;
 139
 140         if (usec >= 1000) {             /* if "big" number, spread normalization to seconds */
 141                 tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
 142                 tmo *= CONFIG_SYS_HZ;           /* find number of "ticks" to wait to achieve target */
 143                 tmo /= 1000;            /* finish normalize. */
 144         } else {                        /* else small number, don't kill it prior to HZ multiply */
 145                 tmo = usec * CONFIG_SYS_HZ;
 146                 tmo /= (1000*1000);
 147         }
 148
 149         endtime = get_timer_masked () + tmo;
 150
 151         do {
 152                 ulong now = get_timer_masked ();
 153                 diff = endtime - now;
 154         } while (diff >= 0);
 155 }
 156
 157 /*
 158  * This function is derived from PowerPC code (read timebase as long long).
 159  * On ARM it just returns the timer value.
 160  */
 161 unsigned long long get_ticks(void)
 162 {
 163         return get_timer(0);
 164 }
 165
 166 /*
 167  * This function is derived from PowerPC code (timebase clock frequency).
 168  * On ARM it returns the number of timer ticks per second.
 169  */
 170 ulong get_tbclk (void)
 171 {
 172         ulong tbclk;
 173
 174         tbclk = CONFIG_SYS_HZ;
 175         return tbclk;
 176 }