arch/arm/cpu/arm926ejs/at91/timer.c

   1 /*
   2  * (C) Copyright 2007-2008
   3  * Stelian Pop <stelian.pop@leadtechdesign.com>
   4  * Lead Tech Design <www.leadtechdesign.com>
   5  *
   6  * See file CREDITS for list of people who contributed to this
   7  * project.
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License as
  11  * published by the Free Software Foundation; either version 2 of
  12  * the License, or (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  22  * MA 02111-1307 USA
  23  */
  24
  25 #include <common.h>
  26 #include <asm/arch/hardware.h>
  27 #include <asm/arch/at91_pit.h>
  28 #include <asm/arch/at91_pmc.h>
  29 #include <asm/arch/clk.h>
  30 #include <asm/arch/io.h>
  31 #include <div64.h>
  32
  33 #if !defined(CONFIG_AT91FAMILY)
  34 # error You need to define CONFIG_AT91FAMILY in your board config!
  35 #endif
  36
  37 DECLARE_GLOBAL_DATA_PTR;
  38
  39 /*
  40  * We're using the AT91CAP9/SAM9 PITC in 32 bit mode, by
  41  * setting the 20 bit counter period to its maximum (0xfffff).
  42  * (See the relevant data sheets to understand that this really works)
  43  *
  44  * We do also mimic the typical powerpc way of incrementing
  45  * two 32 bit registers called tbl and tbu.
  46  *
  47  * Those registers increment at 1/16 the main clock rate.
  48  */
  49
  50 #define TIMER_LOAD_VAL  0xfffff
  51
  52 static inline unsigned long long tick_to_time(unsigned long long tick)
  53 {
  54         tick *= CONFIG_SYS_HZ;
  55         do_div(tick, gd->timer_rate_hz);
  56
  57         return tick;
  58 }
  59
  60 static inline unsigned long long usec_to_tick(unsigned long long usec)
  61 {
  62         usec *= gd->timer_rate_hz;
  63         do_div(usec, 1000000);
  64
  65         return usec;
  66 }
  67
  68 /*
  69  * Use the PITC in full 32 bit incrementing mode
  70  */
  71 int timer_init(void)
  72 {
  73         at91_pmc_t *pmc = (at91_pmc_t *) AT91_PMC_BASE;
  74         at91_pit_t *pit = (at91_pit_t *) AT91_PIT_BASE;
  75
  76         /* Enable PITC Clock */
  77         writel(1 << AT91_ID_SYS, &pmc->pcer);
  78
  79         /* Enable PITC */
  80         writel(TIMER_LOAD_VAL | AT91_PIT_MR_EN , &pit->mr);
  81
  82         gd->timer_rate_hz = gd->mck_rate_hz / 16;
  83         gd->tbu = gd->tbl = 0;
  84
  85         return 0;
  86 }
  87
  88 /*
  89  * Get the current 64 bit timer tick count
  90  */
  91 unsigned long long get_ticks(void)
  92 {
  93         at91_pit_t *pit = (at91_pit_t *) AT91_PIT_BASE;
  94
  95         ulong now = readl(&pit->piir);
  96
  97         /* increment tbu if tbl has rolled over */
  98         if (now < gd->tbl)
  99                 gd->tbu++;
 100         gd->tbl = now;
 101         return (((unsigned long long)gd->tbu) << 32) | gd->tbl;
 102 }
 103
 104 void __udelay(unsigned long usec)
 105 {
 106         unsigned long long tmp;
 107         ulong tmo;
 108
 109         tmo = usec_to_tick(usec);
 110         tmp = get_ticks() + tmo;        /* get current timestamp */
 111
 112         while (get_ticks() < tmp)       /* loop till event */
 113                 ;
 114 }
 115
 116 /*
 117  * reset_timer() and get_timer(base) are a pair of functions that are used by
 118  * some timeout/sleep mechanisms in u-boot.
 119  *
 120  * reset_timer() marks the current time as epoch and
 121  * get_timer(base) works relative to that epoch.
 122  *
 123  * The time is used in CONFIG_SYS_HZ units!
 124  */
 125 void reset_timer(void)
 126 {
 127         gd->timer_reset_value = get_ticks();
 128 }
 129
 130 ulong get_timer(ulong base)
 131 {
 132         return tick_to_time(get_ticks() - gd->timer_reset_value) - base;
 133 }
 134
 135 /*
 136  * Return the number of timer ticks per second.
 137  */
 138 ulong get_tbclk(void)
 139 {
 140         return gd->timer_rate_hz;
 141 }