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
  10 #include <asm/irq.h>
  11
  12 #include <asm/hardware/dec21285.h>
  13 #include <asm/mach/time.h>
  14
  15 #include "common.h"
  16
  17 /*
  18  * Footbridge timer 1 support.
  19  */
  20 static unsigned long timer1_latch;
  21
  22 static unsigned long timer1_gettimeoffset (void)
  23 {
  24         unsigned long value = timer1_latch - *CSR_TIMER1_VALUE;
  25
  26         return ((tick_nsec / 1000) * value) / timer1_latch;
  27 }
  28
  29 static irqreturn_t
  30 timer1_interrupt(int irq, void *dev_id, struct pt_regs *regs)
  31 {
  32         write_seqlock(&xtime_lock);
  33
  34         *CSR_TIMER1_CLR = 0;
  35
  36         timer_tick(regs);
  37
  38         write_sequnlock(&xtime_lock);
  39
  40         return IRQ_HANDLED;
  41 }
  42
  43 static struct irqaction footbridge_timer_irq = {
  44         .name           = "Timer1 timer tick",
  45         .handler        = timer1_interrupt,
  46         .flags          = SA_INTERRUPT,
  47 };
  48
  49 /*
  50  * Set up timer interrupt.
  51  */
  52 static void __init footbridge_timer_init(void)
  53 {
  54         isa_rtc_init();
  55
  56         timer1_latch = (mem_fclk_21285 + 8 * HZ) / (16 * HZ);
  57
  58         *CSR_TIMER1_CLR  = 0;
  59         *CSR_TIMER1_LOAD = timer1_latch;
  60         *CSR_TIMER1_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD | TIMER_CNTL_DIV16;
  61
  62         setup_irq(IRQ_TIMER1, &footbridge_timer_irq);
  63 }
  64
  65 struct sys_timer footbridge_timer = {
  66         .init           = footbridge_timer_init,
  67         .offset         = timer1_gettimeoffset,
  68 };