LXR uboot/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/*
  34 * We're using the AT91CAP9/SAM9 PITC in 32 bit mode, by
  35 * setting the 20 bit counter period to its maximum (0xfffff).
  36 */
  37#define TIMER_LOAD_VAL  0xfffff
  38#define READ_RESET_TIMER at91_sys_read(AT91_PIT_PIVR)
  39#define READ_TIMER at91_sys_read(AT91_PIT_PIIR)
  40
  41static ulong timestamp;
  42static ulong lastinc;
  43static ulong timer_freq;
  44
  45static inline unsigned long long tick_to_time(unsigned long long tick)
  46{
  47        tick *= CONFIG_SYS_HZ;
  48        do_div(tick, timer_freq);
  49
  50        return tick;
  51}
  52
  53static inline unsigned long long usec_to_tick(unsigned long long usec)
  54{
  55        usec *= timer_freq;
  56        do_div(usec, 1000000);
  57
  58        return usec;
  59}
  60
  61/* nothing really to do with interrupts, just starts up a counter. */
  62int timer_init(void)
  63{
  64        /*
  65         * Enable PITC Clock
  66         * The clock is already enabled for system controller in boot
  67         */
  68        at91_sys_write(AT91_PMC_PCER, 1 << AT91_ID_SYS);
  69
  70        /* Enable PITC */
  71        at91_sys_write(AT91_PIT_MR, TIMER_LOAD_VAL | AT91_PIT_PITEN);
  72
  73        reset_timer_masked();
  74
  75        timer_freq = get_mck_clk_rate() >> 4;
  76
  77        return 0;
  78}
  79
  80/*
  81 * timer without interrupts
  82 */
  83unsigned long long get_ticks(void)
  84{
  85        ulong now = READ_TIMER;
  86
  87        if (now >= lastinc)     /* normal mode (non roll) */
  88                /* move stamp forward with absolut diff ticks */
  89                timestamp += (now - lastinc);
  90        else                    /* we have rollover of incrementer */
  91                timestamp += (0xFFFFFFFF - lastinc) + now;
  92        lastinc = now;
  93        return timestamp;
  94}
  95
  96void reset_timer_masked(void)
  97{
  98        /* reset time */
  99        lastinc = READ_TIMER; /* capture current incrementer value time */
 100        timestamp = 0; /* start "advancing" time stamp from 0 */
 101}
 102
 103ulong get_timer_masked(void)
 104{
 105        return tick_to_time(get_ticks());
 106}
 107
 108void udelay(unsigned long usec)
 109{
 110        unsigned long long tmp;
 111        ulong tmo;
 112
 113        tmo = usec_to_tick(usec);
 114        tmp = get_ticks() + tmo;        /* get current timestamp */
 115
 116        while (get_ticks() < tmp)       /* loop till event */
 117                 /*NOP*/;
 118}
 119
 120void reset_timer(void)
 121{
 122        reset_timer_masked();
 123}
 124
 125ulong get_timer(ulong base)
 126{
 127        return get_timer_masked () - base;
 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 */
 134ulong get_tbclk(void)
 135{
 136        ulong tbclk;
 137
 138        tbclk = CONFIG_SYS_HZ;
 139        return tbclk;
 140}
 141