arch/arm/imx-common/timer.c

   1 /*
   2  * (C) Copyright 2007
   3  * Sascha Hauer, Pengutronix
   4  *
   5  * (C) Copyright 2009 Freescale Semiconductor, Inc.
   6  *
   7  * See file CREDITS for list of people who contributed to this
   8  * project.
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License as
  12  * published by the Free Software Foundation; either version 2 of
  13  * the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  23  * MA 02111-1307 USA
  24  */
  25
  26 #include <common.h>
  27 #include <asm/io.h>
  28 #include <div64.h>
  29 #include <asm/arch/imx-regs.h>
  30 #include <asm/arch/clock.h>
  31
  32 /* General purpose timers registers */
  33 struct mxc_gpt {
  34         unsigned int control;
  35         unsigned int prescaler;
  36         unsigned int status;
  37         unsigned int nouse[6];
  38         unsigned int counter;
  39 };
  40
  41 static struct mxc_gpt *cur_gpt = (struct mxc_gpt *)GPT1_BASE_ADDR;
  42
  43 /* General purpose timers bitfields */
  44 #define GPTCR_SWR               (1 << 15)       /* Software reset */
  45 #define GPTCR_FRR               (1 << 9)        /* Freerun / restart */
  46 #define GPTCR_CLKSOURCE_32      (4 << 6)        /* Clock source */
  47 #define GPTCR_TEN               1               /* Timer enable */
  48
  49 DECLARE_GLOBAL_DATA_PTR;
  50
  51 static inline unsigned long long tick_to_time(unsigned long long tick)
  52 {
  53         tick *= CONFIG_SYS_HZ;
  54         do_div(tick, MXC_CLK32);
  55
  56         return tick;
  57 }
  58
  59 static inline unsigned long long us_to_tick(unsigned long long usec)
  60 {
  61         usec = usec * MXC_CLK32 + 999999;
  62         do_div(usec, 1000000);
  63
  64         return usec;
  65 }
  66
  67 int timer_init(void)
  68 {
  69         int i;
  70
  71         /* setup GP Timer 1 */
  72         __raw_writel(GPTCR_SWR, &cur_gpt->control);
  73
  74         /* We have no udelay by now */
  75         for (i = 0; i < 100; i++)
  76                 __raw_writel(0, &cur_gpt->control);
  77
  78         __raw_writel(0, &cur_gpt->prescaler); /* 32Khz */
  79
  80         /* Freerun Mode, PERCLK1 input */
  81         i = __raw_readl(&cur_gpt->control);
  82         __raw_writel(i | GPTCR_CLKSOURCE_32 | GPTCR_TEN, &cur_gpt->control);
  83
  84         gd->arch.tbl = __raw_readl(&cur_gpt->counter);
  85         gd->arch.tbu = 0;
  86
  87         return 0;
  88 }
  89
  90 unsigned long long get_ticks(void)
  91 {
  92         ulong now = __raw_readl(&cur_gpt->counter); /* current tick value */
  93
  94         /* increment tbu if tbl has rolled over */
  95         if (now < gd->arch.tbl)
  96                 gd->arch.tbu++;
  97         gd->arch.tbl = now;
  98         return (((unsigned long long)gd->arch.tbu) << 32) | gd->arch.tbl;
  99 }
 100
 101 ulong get_timer_masked(void)
 102 {
 103         /*
 104          * get_ticks() returns a long long (64 bit), it wraps in
 105          * 2^64 / MXC_CLK32 = 2^64 / 2^15 = 2^49 ~ 5 * 10^14 (s) ~
 106          * 5 * 10^9 days... and get_ticks() * CONFIG_SYS_HZ wraps in
 107          * 5 * 10^6 days - long enough.
 108          */
 109         return tick_to_time(get_ticks());
 110 }
 111
 112 ulong get_timer(ulong base)
 113 {
 114         return get_timer_masked() - base;
 115 }
 116
 117 /* delay x useconds AND preserve advance timstamp value */
 118 void __udelay(unsigned long usec)
 119 {
 120         unsigned long long tmp;
 121         ulong tmo;
 122
 123         tmo = us_to_tick(usec);
 124         tmp = get_ticks() + tmo;        /* get current timestamp */
 125
 126         while (get_ticks() < tmp)       /* loop till event */
 127                  /*NOP*/;
 128 }
 129
 130 /*
 131  * This function is derived from PowerPC code (timebase clock frequency).
 132  * On ARM it returns the number of timer ticks per second.
 133  */
 134 ulong get_tbclk(void)
 135 {
 136         return MXC_CLK32;
 137 }