arch/arm/mach-footbridge/dc21285-timer.c

   1 /*
   2  *  linux/arch/arm/mach-footbridge/dc21285-timer.c
   3  *
   4  *  Copyright (C) 1998 Russell King.
   5  *  Copyright (C) 1998 Phil Blundell
   6  */
   7 #include <linux/init.h>
   8 #include <linux/interrupt.h>
   9 #include <linux/irq.h>
  10 #include <linux/spinlock.h>
  11
  12 #include <asm/irq.h>
  13
  14 #include <asm/hardware/dec21285.h>
  15 #include <asm/mach/time.h>
  16
  17 #include "common.h"
  18
  19 /*
  20  * Footbridge timer 1 support.
  21  */
  22 static unsigned long timer1_latch;
  23
  24 static unsigned long timer1_gettimeoffset (void)
  25 {
  26         unsigned long value = timer1_latch - *CSR_TIMER1_VALUE;
  27
  28         return ((tick_nsec / 1000) * value) / timer1_latch;
  29 }
  30
  31 static irqreturn_t
  32 timer1_interrupt(int irq, void *dev_id)
  33 {
  34         *CSR_TIMER1_CLR = 0;
  35
  36         timer_tick();
  37
  38         return IRQ_HANDLED;
  39 }
  40
  41 static struct irqaction footbridge_timer_irq = {
  42         .name           = "Timer1 timer tick",
  43         .handler        = timer1_interrupt,
  44         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
  45 };
  46
  47 /*
  48  * Set up timer interrupt.
  49  */
  50 static void __init footbridge_timer_init(void)
  51 {
  52         timer1_latch = (mem_fclk_21285 + 8 * HZ) / (16 * HZ);
  53
  54         *CSR_TIMER1_CLR  = 0;
  55         *CSR_TIMER1_LOAD = timer1_latch;
  56         *CSR_TIMER1_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD | TIMER_CNTL_DIV16;
  57
  58         setup_irq(IRQ_TIMER1, &footbridge_timer_irq);
  59 }
  60
  61 struct sys_timer footbridge_timer = {
  62         .init           = footbridge_timer_init,
  63         .offset         = timer1_gettimeoffset,
  64 };