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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/arch/arm/mach-footbridge/isa-timer.c
3 *
4 * Copyright (C) 1998 Russell King.
5 * Copyright (C) 1998 Phil Blundell
6 */
Russell King4e8d7632011-01-28 21:00:39 +00007#include <linux/clockchips.h>
8#include <linux/clocksource.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07009#include <linux/init.h>
10#include <linux/interrupt.h>
Thomas Gleixner55e86982006-07-01 22:32:17 +010011#include <linux/irq.h>
Russell Kingfced80c2008-09-06 12:10:45 +010012#include <linux/io.h>
Russell King4e8d7632011-01-28 21:00:39 +000013#include <linux/timex.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <asm/irq.h>
16
17#include <asm/mach/time.h>
18
19#include "common.h"
20
Russell King4e8d7632011-01-28 21:00:39 +000021#define PIT_MODE 0x43
22#define PIT_CH0 0x40
Linus Torvalds1da177e2005-04-16 15:20:36 -070023
Russell King4e8d7632011-01-28 21:00:39 +000024#define PIT_LATCH ((PIT_TICK_RATE + HZ / 2) / HZ)
25
26static cycle_t pit_read(struct clocksource *cs)
Linus Torvalds1da177e2005-04-16 15:20:36 -070027{
Russell King4e8d7632011-01-28 21:00:39 +000028 unsigned long flags;
29 static int old_count;
30 static u32 old_jifs;
Linus Torvalds1da177e2005-04-16 15:20:36 -070031 int count;
Russell King4e8d7632011-01-28 21:00:39 +000032 u32 jifs;
Linus Torvalds1da177e2005-04-16 15:20:36 -070033
Russell King4e8d7632011-01-28 21:00:39 +000034 raw_local_irq_save(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -070035
Russell King4e8d7632011-01-28 21:00:39 +000036 jifs = jiffies;
37 outb_p(0x00, PIT_MODE); /* latch the count */
38 count = inb_p(PIT_CH0); /* read the latched count */
39 count |= inb_p(PIT_CH0) << 8;
Linus Torvalds1da177e2005-04-16 15:20:36 -070040
Russell King4e8d7632011-01-28 21:00:39 +000041 if (count > old_count && jifs == old_jifs)
42 count = old_count;
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
Russell King4e8d7632011-01-28 21:00:39 +000044 old_count = count;
45 old_jifs = jifs;
Linus Torvalds1da177e2005-04-16 15:20:36 -070046
Russell King4e8d7632011-01-28 21:00:39 +000047 raw_local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
Russell King4e8d7632011-01-28 21:00:39 +000049 count = (PIT_LATCH - 1) - count;
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
Russell King4e8d7632011-01-28 21:00:39 +000051 return (cycle_t)(jifs * PIT_LATCH) + count;
Linus Torvalds1da177e2005-04-16 15:20:36 -070052}
53
Russell King4e8d7632011-01-28 21:00:39 +000054static struct clocksource pit_cs = {
55 .name = "pit",
56 .rating = 110,
57 .read = pit_read,
58 .mask = CLOCKSOURCE_MASK(32),
59};
60
61static void pit_set_mode(enum clock_event_mode mode,
62 struct clock_event_device *evt)
Linus Torvalds1da177e2005-04-16 15:20:36 -070063{
Russell King4e8d7632011-01-28 21:00:39 +000064 unsigned long flags;
65
66 raw_local_irq_save(flags);
67
68 switch (mode) {
69 case CLOCK_EVT_MODE_PERIODIC:
70 outb_p(0x34, PIT_MODE);
71 outb_p(PIT_LATCH & 0xff, PIT_CH0);
72 outb_p(PIT_LATCH >> 8, PIT_CH0);
73 break;
74
75 case CLOCK_EVT_MODE_SHUTDOWN:
76 case CLOCK_EVT_MODE_UNUSED:
77 outb_p(0x30, PIT_MODE);
78 outb_p(0, PIT_CH0);
79 outb_p(0, PIT_CH0);
80 break;
81
82 case CLOCK_EVT_MODE_ONESHOT:
83 case CLOCK_EVT_MODE_RESUME:
84 break;
85 }
86 local_irq_restore(flags);
87}
88
89static int pit_set_next_event(unsigned long delta,
90 struct clock_event_device *evt)
91{
92 return 0;
93}
94
95static struct clock_event_device pit_ce = {
96 .name = "pit",
97 .features = CLOCK_EVT_FEAT_PERIODIC,
98 .set_mode = pit_set_mode,
99 .set_next_event = pit_set_next_event,
100 .shift = 32,
101};
102
103static irqreturn_t pit_timer_interrupt(int irq, void *dev_id)
104{
105 struct clock_event_device *ce = dev_id;
106 ce->event_handler(ce);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 return IRQ_HANDLED;
108}
109
Russell King4e8d7632011-01-28 21:00:39 +0000110static struct irqaction pit_timer_irq = {
111 .name = "pit",
112 .handler = pit_timer_interrupt,
Bernhard Walleb30faba2007-05-08 00:35:39 -0700113 .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
Russell King4e8d7632011-01-28 21:00:39 +0000114 .dev_id = &pit_ce,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115};
116
117static void __init isa_timer_init(void)
118{
Russell King4e8d7632011-01-28 21:00:39 +0000119 pit_ce.cpumask = cpumask_of(smp_processor_id());
120 pit_ce.mult = div_sc(PIT_TICK_RATE, NSEC_PER_SEC, pit_ce.shift);
121 pit_ce.max_delta_ns = clockevent_delta2ns(0x7fff, &pit_ce);
122 pit_ce.min_delta_ns = clockevent_delta2ns(0x000f, &pit_ce);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123
Russell King4e8d7632011-01-28 21:00:39 +0000124 clocksource_register_hz(&pit_cs, PIT_TICK_RATE);
125
126 setup_irq(pit_ce.irq, &pit_timer_irq);
127 clockevents_register_device(&pit_ce);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128}
129
130struct sys_timer isa_timer = {
131 .init = isa_timer_init,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132};