arch/arm/cpu/arm926ejs/mx25/timer.c

   1 /*
   2  * (C) Copyright 2002
   3  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
   4  * Marius Groeger <mgroeger@sysgo.de>
   5  *
   6  * (C) Copyright 2002
   7  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
   8  * Alex Zuepke <azu@sysgo.de>
   9  *
  10  * (C) Copyright 2002
  11  * Gary Jennejohn, DENX Software Engineering, <gj@denx.de>
  12  *
  13  * (C) Copyright 2009
  14  * Ilya Yanok, Emcraft Systems Ltd, <yanok@emcraft.com>
  15  *
  16  * (C) Copyright 2009 DENX Software Engineering
  17  * Author: John Rigby <jrigby@gmail.com>
  18  *      Add support for MX25
  19  *
  20  * See file CREDITS for list of people who contributed to this
  21  * project.
  22  *
  23  * This program is free software; you can redistribute it and/or
  24  * modify it under the terms of the GNU General Public License as
  25  * published by the Free Software Foundation; either version 2 of
  26  * the License, or (at your option) any later version.
  27  *
  28  * This program is distributed in the hope that it will be useful,
  29  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  30  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  31  * GNU General Public License for more details.
  32  *
  33  * You should have received a copy of the GNU General Public License
  34  * along with this program; if not, write to the Free Software
  35  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  36  * MA 02111-1307 USA
  37  */
  38
  39 #include <common.h>
  40 #include <div64.h>
  41 #include <asm/io.h>
  42 #include <asm/arch/imx-regs.h>
  43
  44 static ulong timestamp;
  45 static ulong lastinc;
  46
  47 /*
  48  * "time" is measured in 1 / CONFIG_SYS_HZ seconds,
  49  * "tick" is internal timer period
  50  */
  51 #ifdef CONFIG_MX25_TIMER_HIGH_PRECISION
  52 /* ~0.4% error - measured with stop-watch on 100s boot-delay */
  53 static inline unsigned long long tick_to_time(unsigned long long tick)
  54 {
  55         tick *= CONFIG_SYS_HZ;
  56         do_div(tick, CONFIG_MX25_CLK32);
  57         return tick;
  58 }
  59
  60 static inline unsigned long long time_to_tick(unsigned long long time)
  61 {
  62         time *= CONFIG_MX25_CLK32;
  63         do_div(time, CONFIG_SYS_HZ);
  64         return time;
  65 }
  66
  67 static inline unsigned long long us_to_tick(unsigned long long us)
  68 {
  69         us = us * CONFIG_MX25_CLK32 + 999999;
  70         do_div(us, 1000000);
  71         return us;
  72 }
  73 #else
  74 /* ~2% error */
  75 #define TICK_PER_TIME   ((CONFIG_MX25_CLK32 + CONFIG_SYS_HZ / 2) / \
  76                 CONFIG_SYS_HZ)
  77 #define US_PER_TICK     (1000000 / CONFIG_MX25_CLK32)
  78
  79 static inline unsigned long long tick_to_time(unsigned long long tick)
  80 {
  81         do_div(tick, TICK_PER_TIME);
  82         return tick;
  83 }
  84
  85 static inline unsigned long long time_to_tick(unsigned long long time)
  86 {
  87         return time * TICK_PER_TIME;
  88 }
  89
  90 static inline unsigned long long us_to_tick(unsigned long long us)
  91 {
  92         us += US_PER_TICK - 1;
  93         do_div(us, US_PER_TICK);
  94         return us;
  95 }
  96 #endif
  97
  98 /* nothing really to do with interrupts, just starts up a counter. */
  99 /* The 32KHz 32-bit timer overruns in 134217 seconds */
 100 int timer_init(void)
 101 {
 102         int i;
 103         struct gpt_regs *gpt = (struct gpt_regs *)IMX_GPT1_BASE;
 104         struct ccm_regs *ccm = (struct ccm_regs *)IMX_CCM_BASE;
 105
 106         /* setup GP Timer 1 */
 107         writel(GPT_CTRL_SWR, &gpt->ctrl);
 108
 109         writel(readl(&ccm->cgr1) | CCM_CGR1_GPT1, &ccm->cgr1);
 110
 111         for (i = 0; i < 100; i++)
 112                 writel(0, &gpt->ctrl); /* We have no udelay by now */
 113         writel(0, &gpt->pre); /* prescaler = 1 */
 114         /* Freerun Mode, 32KHz input */
 115         writel(readl(&gpt->ctrl) | GPT_CTRL_CLKSOURCE_32 | GPT_CTRL_FRR,
 116                         &gpt->ctrl);
 117         writel(readl(&gpt->ctrl) | GPT_CTRL_TEN, &gpt->ctrl);
 118
 119         return 0;
 120 }
 121
 122 void reset_timer_masked(void)
 123 {
 124         struct gpt_regs *gpt = (struct gpt_regs *)IMX_GPT1_BASE;
 125         /* reset time */
 126         /* capture current incrementer value time */
 127         lastinc = readl(&gpt->counter);
 128         timestamp = 0; /* start "advancing" time stamp from 0 */
 129 }
 130
 131 void reset_timer(void)
 132 {
 133         reset_timer_masked();
 134 }
 135
 136 unsigned long long get_ticks (void)
 137 {
 138         struct gpt_regs *gpt = (struct gpt_regs *)IMX_GPT1_BASE;
 139         ulong now = readl(&gpt->counter); /* current tick value */
 140
 141         if (now >= lastinc) {
 142                 /*
 143                  * normal mode (non roll)
 144                  * move stamp forward with absolut diff ticks
 145                  */
 146                 timestamp += (now - lastinc);
 147         } else {
 148                 /* we have rollover of incrementer */
 149                 timestamp += (0xFFFFFFFF - lastinc) + now;
 150         }
 151         lastinc = now;
 152         return timestamp;
 153 }
 154
 155 ulong get_timer_masked (void)
 156 {
 157         /*
 158          * get_ticks() returns a long long (64 bit), it wraps in
 159          * 2^64 / CONFIG_MX25_CLK32 = 2^64 / 2^15 = 2^49 ~ 5 * 10^14 (s) ~
 160          * 5 * 10^9 days... and get_ticks() * CONFIG_SYS_HZ wraps in
 161          * 5 * 10^6 days - long enough.
 162          */
 163         return tick_to_time(get_ticks());
 164 }
 165
 166 ulong get_timer (ulong base)
 167 {
 168         return get_timer_masked () - base;
 169 }
 170
 171 void set_timer (ulong t)
 172 {
 173         timestamp = time_to_tick(t);
 174 }
 175
 176 /* delay x useconds AND preserve advance timstamp value */
 177 void __udelay (unsigned long usec)
 178 {
 179         unsigned long long tmp;
 180         ulong tmo;
 181
 182         tmo = us_to_tick(usec);
 183         tmp = get_ticks() + tmo;        /* get current timestamp */
 184
 185         while (get_ticks() < tmp)       /* loop till event */
 186                  /*NOP*/;
 187 }