cpu/arm926ejs/mx27/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  * See file CREDITS for list of people who contributed to this
  17  * project.
  18  *
  19  * This program is free software; you can redistribute it and/or
  20  * modify it under the terms of the GNU General Public License as
  21  * published by the Free Software Foundation; either version 2 of
  22  * the License, or (at your option) any later version.
  23  *
  24  * This program is distributed in the hope that it will be useful,
  25  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  26  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  27  * GNU General Public License for more details.
  28  *
  29  * You should have received a copy of the GNU General Public License
  30  * along with this program; if not, write to the Free Software
  31  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  32  * MA 02111-1307 USA
  33  */
  34
  35 #include <common.h>
  36 #include <div64.h>
  37 #include <asm/io.h>
  38 #include <asm/arch/imx-regs.h>
  39
  40 /* General purpose timers bitfields */
  41 #define GPTCR_SWR               (1 << 15)       /* Software reset       */
  42 #define GPTCR_FRR               (1 << 8)        /* Freerun / restart    */
  43 #define GPTCR_CLKSOURCE_32      (4 << 1)        /* Clock source         */
  44 #define GPTCR_TEN               1               /* Timer enable         */
  45
  46 static ulong timestamp;
  47 static ulong lastinc;
  48
  49 /*
  50  * "time" is measured in 1 / CONFIG_SYS_HZ seconds,
  51  * "tick" is internal timer period
  52  */
  53 #ifdef CONFIG_MX27_TIMER_HIGH_PRECISION
  54 /* ~0.4% error - measured with stop-watch on 100s boot-delay */
  55 static inline unsigned long long tick_to_time(unsigned long long tick)
  56 {
  57         tick *= CONFIG_SYS_HZ;
  58         do_div(tick, CONFIG_MX27_CLK32);
  59         return tick;
  60 }
  61
  62 static inline unsigned long long time_to_tick(unsigned long long time)
  63 {
  64         time *= CONFIG_MX27_CLK32;
  65         do_div(time, CONFIG_SYS_HZ);
  66         return time;
  67 }
  68
  69 static inline unsigned long long us_to_tick(unsigned long long us)
  70 {
  71         us = us * CONFIG_MX27_CLK32 + 999999;
  72         do_div(us, 1000000);
  73         return us;
  74 }
  75 #else
  76 /* ~2% error */
  77 #define TICK_PER_TIME   ((CONFIG_MX27_CLK32 + CONFIG_SYS_HZ / 2) / \
  78                 CONFIG_SYS_HZ)
  79 #define US_PER_TICK     (1000000 / CONFIG_MX27_CLK32)
  80
  81 static inline unsigned long long tick_to_time(unsigned long long tick)
  82 {
  83         do_div(tick, TICK_PER_TIME);
  84         return tick;
  85 }
  86
  87 static inline unsigned long long time_to_tick(unsigned long long time)
  88 {
  89         return time * TICK_PER_TIME;
  90 }
  91
  92 static inline unsigned long long us_to_tick(unsigned long long us)
  93 {
  94         us += US_PER_TICK - 1;
  95         do_div(us, US_PER_TICK);
  96         return us;
  97 }
  98 #endif
  99
 100 /* nothing really to do with interrupts, just starts up a counter. */
 101 /* The 32768Hz 32-bit timer overruns in 131072 seconds */
 102 int timer_init(void)
 103 {
 104         int i;
 105         struct gpt_regs *regs = (struct gpt_regs *)IMX_TIM1_BASE;
 106         struct pll_regs *pll = (struct pll_regs *)IMX_PLL_BASE;
 107
 108         /* setup GP Timer 1 */
 109         writel(GPTCR_SWR, &regs->gpt_tctl);
 110
 111         writel(readl(&pll->pccr0) | PCCR0_GPT1_EN, &pll->pccr0);
 112         writel(readl(&pll->pccr1) | PCCR1_PERCLK1_EN, &pll->pccr1);
 113
 114         for (i = 0; i < 100; i++)
 115                 writel(0, &regs->gpt_tctl); /* We have no udelay by now */
 116         writel(0, &regs->gpt_tprer); /* 32Khz */
 117         /* Freerun Mode, PERCLK1 input */
 118         writel(readl(&regs->gpt_tctl) | GPTCR_CLKSOURCE_32 | GPTCR_FRR,
 119                         &regs->gpt_tctl);
 120         writel(readl(&regs->gpt_tctl) | GPTCR_TEN, &regs->gpt_tctl);
 121
 122         return 0;
 123 }
 124
 125 void reset_timer_masked(void)
 126 {
 127         struct gpt_regs *regs = (struct gpt_regs *)IMX_TIM1_BASE;
 128         /* reset time */
 129         /* capture current incrementer value time */
 130         lastinc = readl(&regs->gpt_tcn);
 131         timestamp = 0; /* start "advancing" time stamp from 0 */
 132 }
 133
 134 void reset_timer(void)
 135 {
 136         reset_timer_masked();
 137 }
 138
 139 unsigned long long get_ticks (void)
 140 {
 141         struct gpt_regs *regs = (struct gpt_regs *)IMX_TIM1_BASE;
 142         ulong now = readl(&regs->gpt_tcn); /* current tick value */
 143
 144         if (now >= lastinc) {
 145                 /*
 146                  * normal mode (non roll)
 147                  * move stamp forward with absolut diff ticks
 148                  */
 149                 timestamp += (now - lastinc);
 150         } else {
 151                 /* we have rollover of incrementer */
 152                 timestamp += (0xFFFFFFFF - lastinc) + now;
 153         }
 154         lastinc = now;
 155         return timestamp;
 156 }
 157
 158 ulong get_timer_masked (void)
 159 {
 160         /*
 161          * get_ticks() returns a long long (64 bit), it wraps in
 162          * 2^64 / CONFIG_MX27_CLK32 = 2^64 / 2^15 = 2^49 ~ 5 * 10^14 (s) ~
 163          * 5 * 10^9 days... and get_ticks() * CONFIG_SYS_HZ wraps in
 164          * 5 * 10^6 days - long enough.
 165          */
 166         return tick_to_time(get_ticks());
 167 }
 168
 169 ulong get_timer (ulong base)
 170 {
 171         return get_timer_masked () - base;
 172 }
 173
 174 void set_timer (ulong t)
 175 {
 176         timestamp = time_to_tick(t);
 177 }
 178
 179 /* delay x useconds AND preserve advance timstamp value */
 180 void __udelay (unsigned long usec)
 181 {
 182         unsigned long long tmp;
 183         ulong tmo;
 184
 185         tmo = us_to_tick(usec);
 186         tmp = get_ticks() + tmo;        /* get current timestamp */
 187
 188         while (get_ticks() < tmp)       /* loop till event */
 189                  /*NOP*/;
 190 }