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 *)(CONFIG_SYS_TIMERBASE+4))
  45
  46 static ulong timestamp;
  47 static ulong lastdec;
  48
  49 #define TIMER_ENABLE    (1 << 7)
  50 #define TIMER_MODE_MSK  (1 << 6)
  51 #define TIMER_MODE_FR   (0 << 6)
  52 #define TIMER_MODE_PD   (1 << 6)
  53
  54 #define TIMER_INT_EN    (1 << 5)
  55 #define TIMER_PRS_MSK   (3 << 2)
  56 #define TIMER_PRS_8S    (1 << 3)
  57 #define TIMER_SIZE_MSK  (1 << 2)
  58 #define TIMER_ONE_SHT   (1 << 0)
  59
  60 int timer_init (void)
  61 {
  62         ulong   tmr_ctrl_val;
  63
  64         /* 1st disable the Timer */
  65         tmr_ctrl_val = *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8);
  66         tmr_ctrl_val &= ~TIMER_ENABLE;
  67         *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8) = tmr_ctrl_val;
  68
  69         /*
  70          * The Timer Control Register has one Undefined/Shouldn't Use Bit
  71          * So we should do read/modify/write Operation
  72          */
  73
  74         /*
  75          * Timer Mode : Free Running
  76          * Interrupt : Disabled
  77          * Prescale : 8 Stage, Clk/256
  78          * Tmr Siz : 16 Bit Counter
  79          * Tmr in Wrapping Mode
  80          */
  81         tmr_ctrl_val = *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8);
  82         tmr_ctrl_val &= ~(TIMER_MODE_MSK | TIMER_INT_EN | TIMER_PRS_MSK | TIMER_SIZE_MSK | TIMER_ONE_SHT );
  83         tmr_ctrl_val |= (TIMER_ENABLE | TIMER_PRS_8S);
  84
  85         *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8) = tmr_ctrl_val;
  86
  87         /* init the timestamp and lastdec value */
  88         reset_timer_masked();
  89
  90         return 0;
  91 }
  92
  93 /*
  94  * timer without interrupts
  95  */
  96
  97 void reset_timer (void)
  98 {
  99         reset_timer_masked ();
 100 }
 101
 102 ulong get_timer (ulong base)
 103 {
 104         return get_timer_masked () - base;
 105 }
 106
 107 void set_timer (ulong t)
 108 {
 109         timestamp = t;
 110 }
 111
 112 /* delay x useconds AND perserve advance timstamp value */
 113 void udelay (unsigned long usec)
 114 {
 115         ulong tmo, tmp;
 116
 117         if(usec >= 1000){               /* if "big" number, spread normalization to seconds */
 118                 tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
 119                 tmo *= CONFIG_SYS_HZ;           /* find number of "ticks" to wait to achieve target */
 120                 tmo /= 1000;            /* finish normalize. */
 121         }else{                          /* else small number, don't kill it prior to HZ multiply */
 122                 tmo = usec * CONFIG_SYS_HZ;
 123                 tmo /= (1000*1000);
 124         }
 125
 126         tmp = get_timer (0);            /* get current timestamp */
 127         if( (tmo + tmp + 1) < tmp )     /* if setting this fordward will roll time stamp */
 128                 reset_timer_masked ();  /* reset "advancing" timestamp to 0, set lastdec value */
 129         else
 130                 tmo += tmp;             /* else, set advancing stamp wake up time */
 131
 132         while (get_timer_masked () < tmo)/* loop till event */
 133                 /*NOP*/;
 134 }
 135
 136 void reset_timer_masked (void)
 137 {
 138         /* reset time */
 139         lastdec = READ_TIMER;  /* capure current decrementer value time */
 140         timestamp = 0;         /* start "advancing" time stamp from 0 */
 141 }
 142
 143 ulong get_timer_masked (void)
 144 {
 145         ulong now = READ_TIMER;         /* current tick value */
 146
 147         if (lastdec >= now) {           /* normal mode (non roll) */
 148                 /* normal mode */
 149                 timestamp += lastdec - now; /* move stamp fordward with absoulte diff ticks */
 150         } else {                        /* we have overflow of the count down timer */
 151                 /* nts = ts + ld + (TLV - now)
 152                  * ts=old stamp, ld=time that passed before passing through -1
 153                  * (TLV-now) amount of time after passing though -1
 154                  * nts = new "advancing time stamp"...it could also roll and cause problems.
 155                  */
 156                 timestamp += lastdec + TIMER_LOAD_VAL - now;
 157         }
 158         lastdec = now;
 159
 160         return timestamp;
 161 }
 162
 163 /* waits specified delay value and resets timestamp */
 164 void udelay_masked (unsigned long usec)
 165 {
 166         ulong tmo;
 167         ulong endtime;
 168         signed long diff;
 169
 170         if (usec >= 1000) {             /* if "big" number, spread normalization to seconds */
 171                 tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
 172                 tmo *= CONFIG_SYS_HZ;           /* find number of "ticks" to wait to achieve target */
 173                 tmo /= 1000;            /* finish normalize. */
 174         } else {                        /* else small number, don't kill it prior to HZ multiply */
 175                 tmo = usec * CONFIG_SYS_HZ;
 176                 tmo /= (1000*1000);
 177         }
 178
 179         endtime = get_timer_masked () + tmo;
 180
 181         do {
 182                 ulong now = get_timer_masked ();
 183                 diff = endtime - now;
 184         } while (diff >= 0);
 185 }
 186
 187 /*
 188  * This function is derived from PowerPC code (read timebase as long long).
 189  * On ARM it just returns the timer value.
 190  */
 191 unsigned long long get_ticks(void)
 192 {
 193         return get_timer(0);
 194 }
 195
 196 /*
 197  * This function is derived from PowerPC code (timebase clock frequency).
 198  * On ARM it returns the number of timer ticks per second.
 199  */
 200 ulong get_tbclk (void)
 201 {
 202         ulong tbclk;
 203
 204         tbclk = CONFIG_SYS_HZ;
 205         return tbclk;
 206 }