arch/arm/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  * SPDX-License-Identifier:     GPL-2.0+
  20  */
  21
  22 #include <common.h>
  23 #include <asm/io.h>
  24
  25 #define TIMER_CLOCK     (CONFIG_SYS_CLK_FREQ / (2 << CONFIG_SYS_PTV))
  26 #define TIMER_LOAD_VAL  0xffffffff
  27
  28 /* macro to read the 32 bit timer */
  29 #define READ_TIMER      readl(CONFIG_SYS_TIMERBASE+8) \
  30                         / (TIMER_CLOCK / CONFIG_SYS_HZ)
  31
  32 DECLARE_GLOBAL_DATA_PTR;
  33
  34 #define timestamp gd->arch.tbl
  35 #define lastdec gd->arch.lastinc
  36
  37 int timer_init (void)
  38 {
  39         int32_t val;
  40
  41         /* Start the decrementer ticking down from 0xffffffff */
  42         *((int32_t *) (CONFIG_SYS_TIMERBASE + LOAD_TIM)) = TIMER_LOAD_VAL;
  43         val = MPUTIM_ST | MPUTIM_AR | MPUTIM_CLOCK_ENABLE | (CONFIG_SYS_PTV << MPUTIM_PTV_BIT);
  44         *((int32_t *) (CONFIG_SYS_TIMERBASE + CNTL_TIMER)) = val;
  45
  46         /* init the timestamp and lastdec value */
  47         reset_timer_masked();
  48
  49         return 0;
  50 }
  51
  52 /*
  53  * timer without interrupts
  54  */
  55 ulong get_timer (ulong base)
  56 {
  57         return get_timer_masked () - base;
  58 }
  59
  60 /* delay x useconds AND preserve advance timestamp value */
  61 void __udelay (unsigned long usec)
  62 {
  63         ulong tmo, tmp;
  64
  65         if(usec >= 1000){               /* if "big" number, spread normalization to seconds */
  66                 tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
  67                 tmo *= CONFIG_SYS_HZ;   /* find number of "ticks" to wait to achieve target */
  68                 tmo /= 1000;            /* finish normalize. */
  69         }else{                          /* else small number, don't kill it prior to HZ multiply */
  70                 tmo = usec * CONFIG_SYS_HZ;
  71                 tmo /= (1000*1000);
  72         }
  73
  74         tmp = get_timer (0);            /* get current timestamp */
  75         if( (tmo + tmp + 1) < tmp )     /* if setting this fordward will roll time stamp */
  76                 reset_timer_masked ();  /* reset "advancing" timestamp to 0, set lastdec value */
  77         else
  78                 tmo += tmp;             /* else, set advancing stamp wake up time */
  79
  80         while (get_timer_masked () < tmo)/* loop till event */
  81                 /*NOP*/;
  82 }
  83
  84 void reset_timer_masked (void)
  85 {
  86         /* reset time */
  87         lastdec = READ_TIMER;  /* capure current decrementer value time */
  88         timestamp = 0;         /* start "advancing" time stamp from 0 */
  89 }
  90
  91 ulong get_timer_masked (void)
  92 {
  93         ulong now = READ_TIMER;         /* current tick value */
  94
  95         if (lastdec >= now) {           /* normal mode (non roll) */
  96                 /* normal mode */
  97                 timestamp += lastdec - now; /* move stamp fordward with absoulte diff ticks */
  98         } else {                        /* we have overflow of the count down timer */
  99                 /* nts = ts + ld + (TLV - now)
 100                  * ts=old stamp, ld=time that passed before passing through -1
 101                  * (TLV-now) amount of time after passing though -1
 102                  * nts = new "advancing time stamp"...it could also roll and cause problems.
 103                  */
 104                 timestamp += lastdec + (TIMER_LOAD_VAL / (TIMER_CLOCK /
 105                                         CONFIG_SYS_HZ)) - now;
 106         }
 107         lastdec = now;
 108
 109         return timestamp;
 110 }
 111
 112 /* waits specified delay value and resets timestamp */
 113 void udelay_masked (unsigned long usec)
 114 {
 115         ulong tmo;
 116         ulong endtime;
 117         signed long diff;
 118
 119         if (usec >= 1000) {             /* if "big" number, spread normalization to seconds */
 120                 tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
 121                 tmo *= CONFIG_SYS_HZ;           /* find number of "ticks" to wait to achieve target */
 122                 tmo /= 1000;            /* finish normalize. */
 123         } else {                        /* else small number, don't kill it prior to HZ multiply */
 124                 tmo = usec * CONFIG_SYS_HZ;
 125                 tmo /= (1000*1000);
 126         }
 127
 128         endtime = get_timer_masked () + tmo;
 129
 130         do {
 131                 ulong now = get_timer_masked ();
 132                 diff = endtime - now;
 133         } while (diff >= 0);
 134 }
 135
 136 /*
 137  * This function is derived from PowerPC code (read timebase as long long).
 138  * On ARM it just returns the timer value.
 139  */
 140 unsigned long long get_ticks(void)
 141 {
 142         return get_timer(0);
 143 }
 144
 145 /*
 146  * This function is derived from PowerPC code (timebase clock frequency).
 147  * On ARM it returns the number of timer ticks per second.
 148  */
 149 ulong get_tbclk (void)
 150 {
 151         return CONFIG_SYS_HZ;
 152 }