2 * linux/arch/arm/mach-footbridge/isa-timer.c
4 * Copyright (C) 1998 Russell King.
5 * Copyright (C) 1998 Phil Blundell
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>
13 #include <linux/spinlock.h>
14 #include <linux/timex.h>
17 #include <asm/i8253.h>
18 #include <asm/mach/time.h>
22 DEFINE_RAW_SPINLOCK(i8253_lock);
24 static void pit_set_mode(enum clock_event_mode mode,
25 struct clock_event_device *evt)
29 raw_local_irq_save(flags);
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);
38 case CLOCK_EVT_MODE_SHUTDOWN:
39 case CLOCK_EVT_MODE_UNUSED:
40 outb_p(0x30, PIT_MODE);
45 case CLOCK_EVT_MODE_ONESHOT:
46 case CLOCK_EVT_MODE_RESUME:
49 local_irq_restore(flags);
52 static int pit_set_next_event(unsigned long delta,
53 struct clock_event_device *evt)
58 static struct clock_event_device pit_ce = {
60 .features = CLOCK_EVT_FEAT_PERIODIC,
61 .set_mode = pit_set_mode,
62 .set_next_event = pit_set_next_event,
66 static irqreturn_t pit_timer_interrupt(int irq, void *dev_id)
68 struct clock_event_device *ce = dev_id;
69 ce->event_handler(ce);
73 static struct irqaction pit_timer_irq = {
75 .handler = pit_timer_interrupt,
76 .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
80 static void __init isa_timer_init(void)
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);
87 clocksource_i8253_init();
89 setup_irq(pit_ce.irq, &pit_timer_irq);
90 clockevents_register_device(&pit_ce);
93 struct sys_timer isa_timer = {
94 .init = isa_timer_init,