LXR uboot/cpu/arm_cortexa8/omap3/timer.c

   1/*
   2 * (C) Copyright 2008
   3 * Texas Instruments
   4 *
   5 * Richard Woodruff <r-woodruff2@ti.com>
   6 * Syed Moahmmed Khasim <khasim@ti.com>
   7 *
   8 * (C) Copyright 2002
   9 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
  10 * Marius Groeger <mgroeger@sysgo.de>
  11 * Alex Zuepke <azu@sysgo.de>
  12 *
  13 * (C) Copyright 2002
  14 * Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
  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 <asm/io.h>
  37
  38static ulong timestamp;
  39static ulong lastinc;
  40static struct gptimer *timer_base = (struct gptimer *)CONFIG_SYS_TIMERBASE;
  41
  42/*
  43 * Nothing really to do with interrupts, just starts up a counter.
  44 * We run the counter with 13MHz, divided by 8, resulting in timer
  45 * frequency of 1.625MHz. With 32bit counter register, counter
  46 * overflows in ~44min
  47 */
  48
  49/* 13MHz / 8 = 1.625MHz */
  50#define TIMER_CLOCK     (V_SCLK / (2 << CONFIG_SYS_PTV))
  51#define TIMER_LOAD_VAL  0xffffffff
  52
  53int timer_init(void)
  54{
  55        /* start the counter ticking up, reload value on overflow */
  56        writel(TIMER_LOAD_VAL, &timer_base->tldr);
  57        /* enable timer */
  58        writel((CONFIG_SYS_PTV << 2) | TCLR_PRE | TCLR_AR | TCLR_ST,
  59                &timer_base->tclr);
  60
  61        reset_timer_masked();   /* init the timestamp and lastinc value */
  62
  63        return 0;
  64}
  65
  66/*
  67 * timer without interrupts
  68 */
  69void reset_timer(void)
  70{
  71        reset_timer_masked();
  72}
  73
  74ulong get_timer(ulong base)
  75{
  76        return get_timer_masked() - base;
  77}
  78
  79void set_timer(ulong t)
  80{
  81        timestamp = t;
  82}
  83
  84/* delay x useconds */
  85void __udelay(unsigned long usec)
  86{
  87        long tmo = usec * (TIMER_CLOCK / 1000) / 1000;
  88        unsigned long now, last = readl(&timer_base->tcrr);
  89
  90        while (tmo > 0) {
  91                now = readl(&timer_base->tcrr);
  92                if (last > now) /* count up timer overflow */
  93                        tmo -= TIMER_LOAD_VAL - last + now;
  94                else
  95                        tmo -= now - last;
  96                last = now;
  97        }
  98}
  99
 100void reset_timer_masked(void)
 101{
 102        /* reset time, capture current incrementer value time */
 103        lastinc = readl(&timer_base->tcrr) / (TIMER_CLOCK / CONFIG_SYS_HZ);
 104        timestamp = 0;          /* start "advancing" time stamp from 0 */
 105}
 106
 107ulong get_timer_masked(void)
 108{
 109        /* current tick value */
 110        ulong now = readl(&timer_base->tcrr) / (TIMER_CLOCK / CONFIG_SYS_HZ);
 111
 112        if (now >= lastinc)     /* normal mode (non roll) */
 113                /* move stamp fordward with absoulte diff ticks */
 114                timestamp += (now - lastinc);
 115        else    /* we have rollover of incrementer */
 116                timestamp += ((TIMER_LOAD_VAL / (TIMER_CLOCK / CONFIG_SYS_HZ))
 117                                - lastinc) + now;
 118        lastinc = now;
 119        return timestamp;
 120}
 121
 122/*
 123 * This function is derived from PowerPC code (read timebase as long long).
 124 * On ARM it just returns the timer value.
 125 */
 126unsigned long long get_ticks(void)
 127{
 128        return get_timer(0);
 129}
 130
 131/*
 132 * This function is derived from PowerPC code (timebase clock frequency).
 133 * On ARM it returns the number of timer ticks per second.
 134 */
 135ulong get_tbclk(void)
 136{
 137        return CONFIG_SYS_HZ;
 138}
 139