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

   1 /*
   2  *  linux/arch/arm/mach-footbridge/isa-timer.c
   3  *
   4  *  Copyright (C) 1998 Russell King.
   5  *  Copyright (C) 1998 Phil Blundell
   6  */
   7 #include <linux/clockchips.h>
   8 #include <linux/clocksource.h>
   9 #include <linux/init.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/irq.h>
  12 #include <linux/io.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/timex.h>
  15
  16 #include <asm/irq.h>
  17 #include <asm/i8253.h>
  18 #include <asm/mach/time.h>
  19
  20 #include "common.h"
  21
  22 DEFINE_RAW_SPINLOCK(i8253_lock);
  23
  24 static void pit_set_mode(enum clock_event_mode mode,
  25         struct clock_event_device *evt)
  26 {
  27         unsigned long flags;
  28
  29         raw_local_irq_save(flags);
  30
  31         switch (mode) {
  32         case CLOCK_EVT_MODE_PERIODIC:
  33                 outb_p(0x34, PIT_MODE);
  34                 outb_p(PIT_LATCH & 0xff, PIT_CH0);
  35                 outb_p(PIT_LATCH >> 8, PIT_CH0);
  36                 break;
  37
  38         case CLOCK_EVT_MODE_SHUTDOWN:
  39         case CLOCK_EVT_MODE_UNUSED:
  40                 outb_p(0x30, PIT_MODE);
  41                 outb_p(0, PIT_CH0);
  42                 outb_p(0, PIT_CH0);
  43                 break;
  44
  45         case CLOCK_EVT_MODE_ONESHOT:
  46         case CLOCK_EVT_MODE_RESUME:
  47                 break;
  48         }
  49         local_irq_restore(flags);
  50 }
  51
  52 static int pit_set_next_event(unsigned long delta,
  53         struct clock_event_device *evt)
  54 {
  55         return 0;
  56 }
  57
  58 static struct clock_event_device pit_ce = {
  59         .name           = "pit",
  60         .features       = CLOCK_EVT_FEAT_PERIODIC,
  61         .set_mode       = pit_set_mode,
  62         .set_next_event = pit_set_next_event,
  63         .shift          = 32,
  64 };
  65
  66 static irqreturn_t pit_timer_interrupt(int irq, void *dev_id)
  67 {
  68         struct clock_event_device *ce = dev_id;
  69         ce->event_handler(ce);
  70         return IRQ_HANDLED;
  71 }
  72
  73 static struct irqaction pit_timer_irq = {
  74         .name           = "pit",
  75         .handler        = pit_timer_interrupt,
  76         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
  77         .dev_id         = &pit_ce,
  78 };
  79
  80 static void __init isa_timer_init(void)
  81 {
  82         pit_ce.cpumask = cpumask_of(smp_processor_id());
  83         pit_ce.mult = div_sc(PIT_TICK_RATE, NSEC_PER_SEC, pit_ce.shift);
  84         pit_ce.max_delta_ns = clockevent_delta2ns(0x7fff, &pit_ce);
  85         pit_ce.min_delta_ns = clockevent_delta2ns(0x000f, &pit_ce);
  86
  87         clocksource_i8253_init();
  88
  89         setup_irq(pit_ce.irq, &pit_timer_irq);
  90         clockevents_register_device(&pit_ce);
  91 }
  92
  93 struct sys_timer isa_timer = {
  94         .init           = isa_timer_init,
  95 };