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  */
  41 static 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  */
  72 static irqreturn_t ks8695_timer_interrupt(int irq, void *dev_id)
  73 {
  74         timer_tick();
  75         return IRQ_HANDLED;
  76 }
  77
  78 static struct irqaction ks8695_timer_irq = {
  79         .name           = "ks8695_tick",
  80         .flags          = IRQF_DISABLED | IRQF_TIMER,
  81         .handler        = ks8695_timer_interrupt,
  82 };
  83
  84 static 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
 100 static 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
 108 struct sys_timer ks8695_timer = {
 109         .init           = ks8695_timer_init,
 110         .offset         = ks8695_gettimeoffset,
 111         .resume         = ks8695_timer_setup,
 112 };
 113
 114 void 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 }