LXR uboot/arch/arm/cpu/arm925t/timer.c

   1/*
   2 * (C) Copyright 2009
   3 * 2N Telekomunikace, <www.2n.cz>
   4 *
   5 * (C) Copyright 2003
   6 * Texas Instruments, <www.ti.com>
   7 *
   8 * (C) Copyright 2002
   9 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
  10 * Marius Groeger <mgroeger@sysgo.de>
  11 *
  12 * (C) Copyright 2002
  13 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
  14 * Alex Zuepke <azu@sysgo.de>
  15 *
  16 * (C) Copyright 2002
  17 * Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
  18 *
  19 * See file CREDITS for list of people who contributed to this
  20 * project.
  21 *
  22 * This program is free software; you can redistribute it and/or
  23 * modify it under the terms of the GNU General Public License as
  24 * published by the Free Software Foundation; either version 2 of
  25 * the License, or (at your option) any later version.
  26 *
  27 * This program is distributed in the hope that it will be useful,
  28 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  29 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  30 * GNU General Public License for more details.
  31 *
  32 * You should have received a copy of the GNU General Public License
  33 * along with this program; if not, write to the Free Software
  34 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  35 * MA 02111-1307 USA
  36 */
  37
  38#include <common.h>
  39#include <arm925t.h>
  40#include <configs/omap1510.h>
  41#include <asm/io.h>
  42
  43#define TIMER_LOAD_VAL  0xffffffff
  44#define TIMER_CLOCK     (CONFIG_SYS_CLK_FREQ / (2 << CONFIG_SYS_PTV))
  45
  46static uint32_t timestamp;
  47static uint32_t lastdec;
  48
  49/* nothing really to do with interrupts, just starts up a counter. */
  50int timer_init (void)
  51{
  52        /* Start the decrementer ticking down from 0xffffffff */
  53        __raw_writel(TIMER_LOAD_VAL, CONFIG_SYS_TIMERBASE + LOAD_TIM);
  54        __raw_writel(MPUTIM_ST | MPUTIM_AR | MPUTIM_CLOCK_ENABLE |
  55                (CONFIG_SYS_PTV << MPUTIM_PTV_BIT),
  56                CONFIG_SYS_TIMERBASE + CNTL_TIMER);
  57
  58        /* init the timestamp and lastdec value */
  59        lastdec = __raw_readl(CONFIG_SYS_TIMERBASE + READ_TIM) /
  60                        (TIMER_CLOCK / CONFIG_SYS_HZ);
  61        timestamp = 0;         /* start "advancing" time stamp from 0 */
  62
  63        return 0;
  64}
  65
  66/*
  67 * timer without interrupts
  68 */
  69ulong get_timer (ulong base)
  70{
  71        return get_timer_masked () - base;
  72}
  73
  74/* delay x useconds AND preserve advance timestamp value */
  75void __udelay (unsigned long usec)
  76{
  77        int32_t tmo = usec * (TIMER_CLOCK / 1000) / 1000;
  78        uint32_t now, last = __raw_readl(CONFIG_SYS_TIMERBASE + READ_TIM);
  79
  80        while (tmo > 0) {
  81                now = __raw_readl(CONFIG_SYS_TIMERBASE + READ_TIM);
  82                if (last < now) /* count down timer underflow */
  83                        tmo -= TIMER_LOAD_VAL - now + last;
  84                else
  85                        tmo -= last - now;
  86                last = now;
  87        }
  88}
  89
  90ulong get_timer_masked (void)
  91{
  92        uint32_t now = __raw_readl(CONFIG_SYS_TIMERBASE + READ_TIM) /
  93                        (TIMER_CLOCK / CONFIG_SYS_HZ);
  94        if (lastdec < now)      /* count down timer underflow */
  95                timestamp += TIMER_LOAD_VAL / (TIMER_CLOCK / CONFIG_SYS_HZ) -
  96                                now + lastdec;
  97        else
  98                timestamp += lastdec - now;
  99        lastdec = now;
 100
 101        return timestamp;
 102}
 103
 104/*
 105 * This function is derived from PowerPC code (read timebase as long long).
 106 * On ARM it just returns the timer value.
 107 */
 108unsigned long long get_ticks(void)
 109{
 110        return get_timer(0);
 111}
 112
 113/*
 114 * This function is derived from PowerPC code (timebase clock frequency).
 115 * On ARM it returns the number of timer ticks per second.
 116 */
 117ulong get_tbclk (void)
 118{
 119        return CONFIG_SYS_HZ;
 120}
 121