LXR linux/arch/arm/mach-ks8695/time.c

   1/*
   2 * arch/arm/mach-ks8695/time.c
   3 *
   4 * Copyright (C) 2006 Ben Dooks <ben@simtec.co.uk>
   5 * Copyright (C) 2006 Simtec Electronics
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License as published by
   9 * the Free Software Foundation; either version 2 of the License, or
  10 * (at your option) any later version.
  11 *
  12 * This program is distributed in the hope that it will be useful,
  13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 *
  17 * You should have received a copy of the GNU General Public License
  18 * along with this program; if not, write to the Free Software
  19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20 */
  21
  22#include <linux/init.h>
  23#include <linux/interrupt.h>
  24#include <linux/irq.h>
  25#include <linux/kernel.h>
  26#include <linux/sched.h>
  27#include <linux/io.h>
  28
  29#include <asm/mach/time.h>
  30#include <asm/system_misc.h>
  31
  32#include <mach/regs-timer.h>
  33#include <mach/regs-irq.h>
  34
  35#include "generic.h"
  36
  37/*
  38 * Returns number of ms since last clock interrupt.  Note that interrupts
  39 * will have been disabled by do_gettimeoffset()
  40 */
  41static unsigned long ks8695_gettimeoffset (void)
  42{
  43        unsigned long elapsed, tick2, intpending;
  44
  45        /*
  46         * Get the current number of ticks.  Note that there is a race
  47         * condition between us reading the timer and checking for an
  48         * interrupt.  We solve this by ensuring that the counter has not
  49         * reloaded between our two reads.
  50         */
  51        elapsed = __raw_readl(KS8695_TMR_VA + KS8695_T1TC) + __raw_readl(KS8695_TMR_VA + KS8695_T1PD);
  52        do {
  53                tick2 = elapsed;
  54                intpending = __raw_readl(KS8695_IRQ_VA + KS8695_INTST) & (1 << KS8695_IRQ_TIMER1);
  55                elapsed = __raw_readl(KS8695_TMR_VA + KS8695_T1TC) + __raw_readl(KS8695_TMR_VA + KS8695_T1PD);
  56        } while (elapsed > tick2);
  57
  58        /* Convert to number of ticks expired (not remaining) */
  59        elapsed = (CLOCK_TICK_RATE / HZ) - elapsed;
  60
  61        /* Is interrupt pending?  If so, then timer has been reloaded already. */
  62        if (intpending)
  63                elapsed += (CLOCK_TICK_RATE / HZ);
  64
  65        /* Convert ticks to usecs */
  66        return (unsigned long)(elapsed * (tick_nsec / 1000)) / LATCH;
  67}
  68
  69/*
  70 * IRQ handler for the timer.
  71 */
  72static irqreturn_t ks8695_timer_interrupt(int irq, void *dev_id)
  73{
  74        timer_tick();
  75        return IRQ_HANDLED;
  76}
  77
  78static struct irqaction ks8695_timer_irq = {
  79        .name           = "ks8695_tick",
  80        .flags          = IRQF_DISABLED | IRQF_TIMER,
  81        .handler        = ks8695_timer_interrupt,
  82};
  83
  84static void ks8695_timer_setup(void)
  85{
  86        unsigned long tmout = CLOCK_TICK_RATE / HZ;
  87        unsigned long tmcon;
  88
  89        /* disable timer1 */
  90        tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
  91        __raw_writel(tmcon & ~TMCON_T1EN, KS8695_TMR_VA + KS8695_TMCON);
  92
  93        __raw_writel(tmout / 2, KS8695_TMR_VA + KS8695_T1TC);
  94        __raw_writel(tmout / 2, KS8695_TMR_VA + KS8695_T1PD);
  95
  96        /* re-enable timer1 */
  97        __raw_writel(tmcon | TMCON_T1EN, KS8695_TMR_VA + KS8695_TMCON);
  98}
  99
 100static void __init ks8695_timer_init (void)
 101{
 102        ks8695_timer_setup();
 103
 104        /* Enable timer interrupts */
 105        setup_irq(KS8695_IRQ_TIMER1, &ks8695_timer_irq);
 106}
 107
 108struct sys_timer ks8695_timer = {
 109        .init           = ks8695_timer_init,
 110        .offset         = ks8695_gettimeoffset,
 111        .resume         = ks8695_timer_setup,
 112};
 113
 114void ks8695_restart(char mode, const char *cmd)
 115{
 116        unsigned int reg;
 117
 118        if (mode == 's')
 119                soft_restart(0);
 120
 121        /* disable timer0 */
 122        reg = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
 123        __raw_writel(reg & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
 124
 125        /* enable watchdog mode */
 126        __raw_writel((10 << 8) | T0TC_WATCHDOG, KS8695_TMR_VA + KS8695_T0TC);
 127
 128        /* re-enable timer0 */
 129        __raw_writel(reg | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
 130}
 131