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, <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+4))
  44
  45 static ulong timestamp;
  46 static ulong lastdec;
  47
  48 #define TIMER_ENABLE    (1 << 7)
  49 #define TIMER_MODE_MSK  (1 << 6)
  50 #define TIMER_MODE_FR   (0 << 6)
  51 #define TIMER_MODE_PD   (1 << 6)
  52
  53 #define TIMER_INT_EN    (1 << 5)
  54 #define TIMER_PRS_MSK   (3 << 2)
  55 #define TIMER_PRS_8S    (1 << 3)
  56 #define TIMER_SIZE_MSK  (1 << 2)
  57 #define TIMER_ONE_SHT   (1 << 0)
  58
  59 int timer_init (void)
  60 {
  61         ulong   tmr_ctrl_val;
  62
  63         /* 1st disable the Timer */
  64         tmr_ctrl_val = *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8);
  65         tmr_ctrl_val &= ~TIMER_ENABLE;
  66         *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8) = tmr_ctrl_val;
  67
  68         /*
  69          * The Timer Control Register has one Undefined/Shouldn't Use Bit
  70          * So we should do read/modify/write Operation
  71          */
  72
  73         /*
  74          * Timer Mode : Free Running
  75          * Interrupt : Disabled
  76          * Prescale : 8 Stage, Clk/256
  77          * Tmr Siz : 16 Bit Counter
  78          * Tmr in Wrapping Mode
  79          */
  80         tmr_ctrl_val = *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8);
  81         tmr_ctrl_val &= ~(TIMER_MODE_MSK | TIMER_INT_EN | TIMER_PRS_MSK | TIMER_SIZE_MSK | TIMER_ONE_SHT );
  82         tmr_ctrl_val |= (TIMER_ENABLE | TIMER_PRS_8S);
  83
  84         *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8) = tmr_ctrl_val;
  85
  86         /* init the timestamp and lastdec value */
  87         reset_timer_masked();
  88
  89         return 0;
  90 }
  91
  92 /*
  93  * timer without interrupts
  94  */
  95
  96 void reset_timer (void)
  97 {
  98         reset_timer_masked ();
  99 }
 100
 101 ulong get_timer (ulong base)
 102 {
 103         return get_timer_masked () - base;
 104 }
 105
 106 void set_timer (ulong t)
 107 {
 108         timestamp = t;
 109 }
 110
 111 /* delay x useconds AND perserve advance timstamp value */
 112 void __udelay (unsigned long usec)
 113 {
 114         ulong tmo, tmp;
 115
 116         if(usec >= 1000){               /* if "big" number, spread normalization to seconds */
 117                 tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
 118                 tmo *= CONFIG_SYS_HZ;           /* find number of "ticks" to wait to achieve target */
 119                 tmo /= 1000;            /* finish normalize. */
 120         }else{                          /* else small number, don't kill it prior to HZ multiply */
 121                 tmo = usec * CONFIG_SYS_HZ;
 122                 tmo /= (1000*1000);
 123         }
 124
 125         tmp = get_timer (0);            /* get current timestamp */
 126         if( (tmo + tmp + 1) < tmp )     /* if setting this fordward will roll time stamp */
 127                 reset_timer_masked ();  /* reset "advancing" timestamp to 0, set lastdec value */
 128         else
 129                 tmo += tmp;             /* else, set advancing stamp wake up time */
 130
 131         while (get_timer_masked () < tmo)/* loop till event */
 132                 /*NOP*/;
 133 }
 134
 135 void reset_timer_masked (void)
 136 {
 137         /* reset time */
 138         lastdec = READ_TIMER;  /* capure current decrementer value time */
 139         timestamp = 0;         /* start "advancing" time stamp from 0 */
 140 }
 141
 142 ulong get_timer_masked (void)
 143 {
 144         ulong now = READ_TIMER;         /* current tick value */
 145
 146         if (lastdec >= now) {           /* normal mode (non roll) */
 147                 /* normal mode */
 148                 timestamp += lastdec - now; /* move stamp fordward with absoulte diff ticks */
 149         } else {                        /* we have overflow of the count down timer */
 150                 /* nts = ts + ld + (TLV - now)
 151                  * ts=old stamp, ld=time that passed before passing through -1
 152                  * (TLV-now) amount of time after passing though -1
 153                  * nts = new "advancing time stamp"...it could also roll and cause problems.
 154                  */
 155                 timestamp += lastdec + TIMER_LOAD_VAL - now;
 156         }
 157         lastdec = now;
 158
 159         return timestamp;
 160 }
 161
 162 /* waits specified delay value and resets timestamp */
 163 void udelay_masked (unsigned long usec)
 164 {
 165         ulong tmo;
 166         ulong endtime;
 167         signed long diff;
 168
 169         if (usec >= 1000) {             /* if "big" number, spread normalization to seconds */
 170                 tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
 171                 tmo *= CONFIG_SYS_HZ;           /* find number of "ticks" to wait to achieve target */
 172                 tmo /= 1000;            /* finish normalize. */
 173         } else {                        /* else small number, don't kill it prior to HZ multiply */
 174                 tmo = usec * CONFIG_SYS_HZ;
 175                 tmo /= (1000*1000);
 176         }
 177
 178         endtime = get_timer_masked () + tmo;
 179
 180         do {
 181                 ulong now = get_timer_masked ();
 182                 diff = endtime - now;
 183         } while (diff >= 0);
 184 }
 185
 186 /*
 187  * This function is derived from PowerPC code (read timebase as long long).
 188  * On ARM it just returns the timer value.
 189  */
 190 unsigned long long get_ticks(void)
 191 {
 192         return get_timer(0);
 193 }
 194
 195 /*
 196  * This function is derived from PowerPC code (timebase clock frequency).
 197  * On ARM it returns the number of timer ticks per second.
 198  */
 199 ulong get_tbclk (void)
 200 {
 201         ulong tbclk;
 202
 203         tbclk = CONFIG_SYS_HZ;
 204         return tbclk;
 205 }