LXR uboot/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
  37DECLARE_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
  52static 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
  60static 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 */
  71int 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 */
  91unsigned 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
 104void __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 */
 125void reset_timer(void)
 126{
 127        gd->timer_reset_value = get_ticks();
 128}
 129
 130ulong 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 */
 138ulong get_tbclk(void)
 139{
 140        return gd->timer_rate_hz;
 141}
 142