Merge commit 'v2.6.39' into 20110526
[linux-2.6.git] / 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/timex.h>
14
15 #include <asm/irq.h>
16
17 #include <asm/mach/time.h>
18
19 #include "common.h"
20
21 #define PIT_MODE        0x43
22 #define PIT_CH0         0x40
23
24 #define PIT_LATCH       ((PIT_TICK_RATE + HZ / 2) / HZ)
25
26 static cycle_t pit_read(struct clocksource *cs)
27 {
28         unsigned long flags;
29         static int old_count;
30         static u32 old_jifs;
31         int count;
32         u32 jifs;
33
34         raw_local_irq_save(flags);
35
36         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;
40
41         if (count > old_count && jifs == old_jifs)
42                 count = old_count;
43
44         old_count = count;
45         old_jifs = jifs;
46
47         raw_local_irq_restore(flags);
48
49         count = (PIT_LATCH - 1) - count;
50
51         return (cycle_t)(jifs * PIT_LATCH) + count;
52 }
53
54 static struct clocksource pit_cs = {
55         .name           = "pit",
56         .rating         = 110,
57         .read           = pit_read,
58         .mask           = CLOCKSOURCE_MASK(32),
59 };
60
61 static void pit_set_mode(enum clock_event_mode mode,
62         struct clock_event_device *evt)
63 {
64         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
89 static int pit_set_next_event(unsigned long delta,
90         struct clock_event_device *evt)
91 {
92         return 0;
93 }
94
95 static 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
103 static irqreturn_t pit_timer_interrupt(int irq, void *dev_id)
104 {
105         struct clock_event_device *ce = dev_id;
106         ce->event_handler(ce);
107         return IRQ_HANDLED;
108 }
109
110 static struct irqaction pit_timer_irq = {
111         .name           = "pit",
112         .handler        = pit_timer_interrupt,
113         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
114         .dev_id         = &pit_ce,
115 };
116
117 static void __init isa_timer_init(void)
118 {
119         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);
123
124         clocksource_register_hz(&pit_cs, PIT_TICK_RATE);
125
126         setup_irq(pit_ce.irq, &pit_timer_irq);
127         clockevents_register_device(&pit_ce);
128 }
129
130 struct sys_timer isa_timer = {
131         .init           = isa_timer_init,
132 };