cpu/arm1136/mx31/timer.c

   1 /*
   2  * (C) Copyright 2007
   3  * Sascha Hauer, Pengutronix
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23
  24 #include <common.h>
  25 #include <asm/arch/mx31-regs.h>
  26 #include <div64.h>
  27
  28 #define TIMER_BASE 0x53f90000 /* General purpose timer 1 */
  29
  30 /* General purpose timers registers */
  31 #define GPTCR   __REG(TIMER_BASE)               /* Control register     */
  32 #define GPTPR   __REG(TIMER_BASE + 0x4)         /* Prescaler register   */
  33 #define GPTSR   __REG(TIMER_BASE + 0x8)         /* Status register      */
  34 #define GPTCNT  __REG(TIMER_BASE + 0x24)        /* Counter register     */
  35
  36 /* General purpose timers bitfields */
  37 #define GPTCR_SWR               (1 << 15)       /* Software reset       */
  38 #define GPTCR_FRR               (1 << 9)        /* Freerun / restart    */
  39 #define GPTCR_CLKSOURCE_32      (4 << 6)        /* Clock source         */
  40 #define GPTCR_TEN               1               /* Timer enable         */
  41
  42 static ulong timestamp;
  43 static ulong lastinc;
  44
  45 /* "time" is measured in 1 / CONFIG_SYS_HZ seconds, "tick" is internal timer period */
  46 #ifdef CONFIG_MX31_TIMER_HIGH_PRECISION
  47 /* ~0.4% error - measured with stop-watch on 100s boot-delay */
  48 static inline unsigned long long tick_to_time(unsigned long long tick)
  49 {
  50         tick *= CONFIG_SYS_HZ;
  51         do_div(tick, CONFIG_MX31_CLK32);
  52         return tick;
  53 }
  54
  55 static inline unsigned long long time_to_tick(unsigned long long time)
  56 {
  57         time *= CONFIG_MX31_CLK32;
  58         do_div(time, CONFIG_SYS_HZ);
  59         return time;
  60 }
  61
  62 static inline unsigned long long us_to_tick(unsigned long long us)
  63 {
  64         us = us * CONFIG_MX31_CLK32 + 999999;
  65         do_div(us, 1000000);
  66         return us;
  67 }
  68 #else
  69 /* ~2% error */
  70 #define TICK_PER_TIME   ((CONFIG_MX31_CLK32 + CONFIG_SYS_HZ / 2) / CONFIG_SYS_HZ)
  71 #define US_PER_TICK     (1000000 / CONFIG_MX31_CLK32)
  72
  73 static inline unsigned long long tick_to_time(unsigned long long tick)
  74 {
  75         do_div(tick, TICK_PER_TIME);
  76         return tick;
  77 }
  78
  79 static inline unsigned long long time_to_tick(unsigned long long time)
  80 {
  81         return time * TICK_PER_TIME;
  82 }
  83
  84 static inline unsigned long long us_to_tick(unsigned long long us)
  85 {
  86         us += US_PER_TICK - 1;
  87         do_div(us, US_PER_TICK);
  88         return us;
  89 }
  90 #endif
  91
  92 /* The 32768Hz 32-bit timer overruns in 131072 seconds */
  93 int timer_init (void)
  94 {
  95         int i;
  96
  97         /* setup GP Timer 1 */
  98         GPTCR = GPTCR_SWR;
  99         for (i = 0; i < 100; i++)
 100                 GPTCR = 0; /* We have no udelay by now */
 101         GPTPR = 0; /* 32Khz */
 102         /* Freerun Mode, PERCLK1 input */
 103         GPTCR |= GPTCR_CLKSOURCE_32 | GPTCR_TEN;
 104
 105         return 0;
 106 }
 107
 108 void reset_timer_masked (void)
 109 {
 110         /* reset time */
 111         lastinc = GPTCNT; /* capture current incrementer value time */
 112         timestamp = 0; /* start "advancing" time stamp from 0 */
 113 }
 114
 115 void reset_timer(void)
 116 {
 117         reset_timer_masked();
 118 }
 119
 120 unsigned long long get_ticks (void)
 121 {
 122         ulong now = GPTCNT; /* current tick value */
 123
 124         if (now >= lastinc)     /* normal mode (non roll) */
 125                 /* move stamp forward with absolut diff ticks */
 126                 timestamp += (now - lastinc);
 127         else                    /* we have rollover of incrementer */
 128                 timestamp += (0xFFFFFFFF - lastinc) + now;
 129         lastinc = now;
 130         return timestamp;
 131 }
 132
 133 ulong get_timer_masked (void)
 134 {
 135         /*
 136          * get_ticks() returns a long long (64 bit), it wraps in
 137          * 2^64 / CONFIG_MX31_CLK32 = 2^64 / 2^15 = 2^49 ~ 5 * 10^14 (s) ~
 138          * 5 * 10^9 days... and get_ticks() * CONFIG_SYS_HZ wraps in
 139          * 5 * 10^6 days - long enough.
 140          */
 141         return tick_to_time(get_ticks());
 142 }
 143
 144 ulong get_timer (ulong base)
 145 {
 146         return get_timer_masked () - base;
 147 }
 148
 149 void set_timer (ulong t)
 150 {
 151         timestamp = time_to_tick(t);
 152 }
 153
 154 /* delay x useconds AND perserve advance timstamp value */
 155 void __udelay (unsigned long usec)
 156 {
 157         unsigned long long tmp;
 158         ulong tmo;
 159
 160         tmo = us_to_tick(usec);
 161         tmp = get_ticks() + tmo;        /* get current timestamp */
 162
 163         while (get_ticks() < tmp)       /* loop till event */
 164                  /*NOP*/;
 165 }
 166
 167 void reset_cpu (ulong addr)
 168 {
 169         __REG16(WDOG_BASE) = 4;
 170 }