arch/arm/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 DECLARE_GLOBAL_DATA_PTR;
  47
  48 #define timestamp gd->tbl
  49 #define lastinc gd->lastinc
  50
  51 /*
  52  * "time" is measured in 1 / CONFIG_SYS_HZ seconds,
  53  * "tick" is internal timer period
  54  */
  55 #ifdef CONFIG_MX27_TIMER_HIGH_PRECISION
  56 /* ~0.4% error - measured with stop-watch on 100s boot-delay */
  57 static inline unsigned long long tick_to_time(unsigned long long tick)
  58 {
  59         tick *= CONFIG_SYS_HZ;
  60         do_div(tick, CONFIG_MX27_CLK32);
  61         return tick;
  62 }
  63
  64 static inline unsigned long long time_to_tick(unsigned long long time)
  65 {
  66         time *= CONFIG_MX27_CLK32;
  67         do_div(time, CONFIG_SYS_HZ);
  68         return time;
  69 }
  70
  71 static inline unsigned long long us_to_tick(unsigned long long us)
  72 {
  73         us = us * CONFIG_MX27_CLK32 + 999999;
  74         do_div(us, 1000000);
  75         return us;
  76 }
  77 #else
  78 /* ~2% error */
  79 #define TICK_PER_TIME   ((CONFIG_MX27_CLK32 + CONFIG_SYS_HZ / 2) / \
  80                 CONFIG_SYS_HZ)
  81 #define US_PER_TICK     (1000000 / CONFIG_MX27_CLK32)
  82
  83 static inline unsigned long long tick_to_time(unsigned long long tick)
  84 {
  85         do_div(tick, TICK_PER_TIME);
  86         return tick;
  87 }
  88
  89 static inline unsigned long long time_to_tick(unsigned long long time)
  90 {
  91         return time * TICK_PER_TIME;
  92 }
  93
  94 static inline unsigned long long us_to_tick(unsigned long long us)
  95 {
  96         us += US_PER_TICK - 1;
  97         do_div(us, US_PER_TICK);
  98         return us;
  99 }
 100 #endif
 101
 102 /* nothing really to do with interrupts, just starts up a counter. */
 103 /* The 32768Hz 32-bit timer overruns in 131072 seconds */
 104 int timer_init(void)
 105 {
 106         int i;
 107         struct gpt_regs *regs = (struct gpt_regs *)IMX_TIM1_BASE;
 108         struct pll_regs *pll = (struct pll_regs *)IMX_PLL_BASE;
 109
 110         /* setup GP Timer 1 */
 111         writel(GPTCR_SWR, &regs->gpt_tctl);
 112
 113         writel(readl(&pll->pccr0) | PCCR0_GPT1_EN, &pll->pccr0);
 114         writel(readl(&pll->pccr1) | PCCR1_PERCLK1_EN, &pll->pccr1);
 115
 116         for (i = 0; i < 100; i++)
 117                 writel(0, &regs->gpt_tctl); /* We have no udelay by now */
 118         writel(0, &regs->gpt_tprer); /* 32Khz */
 119         /* Freerun Mode, PERCLK1 input */
 120         writel(readl(&regs->gpt_tctl) | GPTCR_CLKSOURCE_32 | GPTCR_FRR,
 121                         &regs->gpt_tctl);
 122         writel(readl(&regs->gpt_tctl) | GPTCR_TEN, &regs->gpt_tctl);
 123
 124         return 0;
 125 }
 126
 127 void reset_timer_masked(void)
 128 {
 129         struct gpt_regs *regs = (struct gpt_regs *)IMX_TIM1_BASE;
 130         /* reset time */
 131         /* capture current incrementer value time */
 132         lastinc = readl(&regs->gpt_tcn);
 133         timestamp = 0; /* start "advancing" time stamp from 0 */
 134 }
 135
 136 unsigned long long get_ticks (void)
 137 {
 138         struct gpt_regs *regs = (struct gpt_regs *)IMX_TIM1_BASE;
 139         ulong now = readl(&regs->gpt_tcn); /* 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_MX27_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 /* delay x useconds AND preserve advance timstamp value */
 172 void __udelay (unsigned long usec)
 173 {
 174         unsigned long long tmp;
 175         ulong tmo;
 176
 177         tmo = us_to_tick(usec);
 178         tmp = get_ticks() + tmo;        /* get current timestamp */
 179
 180         while (get_ticks() < tmp)       /* loop till event */
 181                  /*NOP*/;
 182 }