cpu/arm1136/omap24xx/timer.c

   1 /*
   2  * (C) Copyright 2004
   3  * Texas Instruments
   4  * Richard Woodruff <r-woodruff2@ti.com>
   5  *
   6  * (C) Copyright 2002
   7  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
   8  * Marius Groeger <mgroeger@sysgo.de>
   9  * Alex Zuepke <azu@sysgo.de>
  10  *
  11  * (C) Copyright 2002
  12  * Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
  13  *
  14  * See file CREDITS for list of people who contributed to this
  15  * project.
  16  *
  17  * This program is free software; you can redistribute it and/or
  18  * modify it under the terms of the GNU General Public License as
  19  * published by the Free Software Foundation; either version 2 of
  20  * the License, or (at your option) any later version.
  21  *
  22  * This program is distributed in the hope that it will be useful,
  23  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  24  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  25  * GNU General Public License for more details.
  26  *
  27  * You should have received a copy of the GNU General Public License
  28  * along with this program; if not, write to the Free Software
  29  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  30  * MA 02111-1307 USA
  31  */
  32
  33 #include <common.h>
  34 #include <asm/arch/bits.h>
  35 #include <asm/arch/omap2420.h>
  36
  37 #define TIMER_LOAD_VAL 0
  38
  39 /* macro to read the 32 bit timer */
  40 #define READ_TIMER (*((volatile ulong *)(CONFIG_SYS_TIMERBASE+TCRR)))
  41
  42 static ulong timestamp;
  43 static ulong lastinc;
  44
  45 int timer_init (void)
  46 {
  47         int32_t val;
  48
  49         /* Start the counter ticking up */
  50         *((int32_t *) (CONFIG_SYS_TIMERBASE + TLDR)) = TIMER_LOAD_VAL;  /* reload value on overflow*/
  51         val = (CONFIG_SYS_PTV << 2) | BIT5 | BIT1 | BIT0;               /* mask to enable timer*/
  52         *((int32_t *) (CONFIG_SYS_TIMERBASE + TCLR)) = val;     /* start timer */
  53
  54         reset_timer_masked(); /* init the timestamp and lastinc value */
  55
  56         return(0);
  57 }
  58 /*
  59  * timer without interrupts
  60  */
  61 void reset_timer (void)
  62 {
  63         reset_timer_masked ();
  64 }
  65
  66 ulong get_timer (ulong base)
  67 {
  68         return get_timer_masked () - base;
  69 }
  70
  71 void set_timer (ulong t)
  72 {
  73         timestamp = t;
  74 }
  75
  76 /* delay x useconds AND perserve advance timstamp value */
  77 void udelay (unsigned long usec)
  78 {
  79         ulong tmo, tmp;
  80
  81         if (usec >= 1000) {                     /* if "big" number, spread normalization to seconds */
  82                 tmo = usec / 1000;              /* start to normalize for usec to ticks per sec */
  83                 tmo *= CONFIG_SYS_HZ;                   /* find number of "ticks" to wait to achieve target */
  84                 tmo /= 1000;                    /* finish normalize. */
  85         } else {                                        /* else small number, don't kill it prior to HZ multiply */
  86                 tmo = usec * CONFIG_SYS_HZ;
  87                 tmo /= (1000*1000);
  88         }
  89
  90         tmp = get_timer (0);            /* get current timestamp */
  91         if ( (tmo + tmp + 1) < tmp )/* if setting this forward will roll time stamp */
  92                 reset_timer_masked ();  /* reset "advancing" timestamp to 0, set lastinc value */
  93         else
  94                 tmo     += tmp;                         /* else, set advancing stamp wake up time */
  95         while (get_timer_masked () < tmo)/* loop till event */
  96                 /*NOP*/;
  97 }
  98
  99 void reset_timer_masked (void)
 100 {
 101         /* reset time */
 102         lastinc = READ_TIMER;           /* capture current incrementer value time */
 103         timestamp = 0;                          /* start "advancing" time stamp from 0 */
 104 }
 105
 106 ulong get_timer_masked (void)
 107 {
 108         ulong now = READ_TIMER;         /* current tick value */
 109
 110         if (now >= lastinc)                     /* normal mode (non roll) */
 111                 timestamp += (now - lastinc); /* move stamp fordward with absoulte diff ticks */
 112         else                                            /* we have rollover of incrementer */
 113                 timestamp += (0xFFFFFFFF - lastinc) + now;
 114         lastinc = now;
 115         return timestamp;
 116 }
 117
 118 /* waits specified delay value and resets timestamp */
 119 void udelay_masked (unsigned long usec)
 120 {
 121         ulong tmo;
 122         ulong endtime;
 123         signed long diff;
 124
 125         if (usec >= 1000) {                     /* if "big" number, spread normalization to seconds */
 126                 tmo = usec / 1000;              /* start to normalize for usec to ticks per sec */
 127                 tmo *= CONFIG_SYS_HZ;                   /* find number of "ticks" to wait to achieve target */
 128                 tmo /= 1000;                    /* finish normalize. */
 129         } else {                                        /* else small number, don't kill it prior to HZ multiply */
 130                 tmo = usec * CONFIG_SYS_HZ;
 131                 tmo /= (1000*1000);
 132         }
 133         endtime = get_timer_masked () + tmo;
 134
 135         do {
 136                 ulong now = get_timer_masked ();
 137                 diff = endtime - now;
 138         } while (diff >= 0);
 139 }
 140
 141 /*
 142  * This function is derived from PowerPC code (read timebase as long long).
 143  * On ARM it just returns the timer value.
 144  */
 145 unsigned long long get_ticks(void)
 146 {
 147         return get_timer(0);
 148 }
 149 /*
 150  * This function is derived from PowerPC code (timebase clock frequency).
 151  * On ARM it returns the number of timer ticks per second.
 152  */
 153 ulong get_tbclk (void)
 154 {
 155         ulong tbclk;
 156         tbclk = CONFIG_SYS_HZ;
 157         return tbclk;
 158 }