aboutsummaryrefslogtreecommitdiffstats
path: root/arch/arm/mach-sa1100/time.c
blob: 51c05292d145cb3f7de2b2f96116d83cbc23475f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
/*
 * linux/arch/arm/mach-sa1100/time.c
 *
 * Copyright (C) 1998 Deborah Wallach.
 * Twiddles  (C) 1999 Hugo Fiennes <hugo@empeg.com>
 *
 * 2000/03/29 (C) Nicolas Pitre <nico@fluxnic.net>
 *	Rewritten: big cleanup, much simpler, better HZ accuracy.
 *
 */
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/sched.h>	/* just for sched_clock() - funny that */
#include <linux/timex.h>
#include <linux/clockchips.h>

#include <asm/mach/time.h>
#include <asm/sched_clock.h>
#include <mach/hardware.h>

/*
 * This is the SA11x0 sched_clock implementation.
 */
static DEFINE_CLOCK_DATA(cd);

/*
 * Constants generated by clocks_calc_mult_shift(m, s, 3.6864MHz,
 * NSEC_PER_SEC, 60).
 * This gives a resolution of about 271ns and a wrap period of about 19min.
 */
#define SC_MULT		2275555556u
#define SC_SHIFT	23

unsigned long long notrace sched_clock(void)
{
	u32 cyc = OSCR;
	return cyc_to_fixed_sched_clock(&cd, cyc, (u32)~0, SC_MULT, SC_SHIFT);
}

static void notrace sa1100_update_sched_clock(void)
{
	u32 cyc = OSCR;
	update_sched_clock(&cd, cyc, (u32)~0);
}

#define MIN_OSCR_DELTA 2

static irqreturn_t sa1100_ost0_interrupt(int irq, void *dev_id)
{
	struct clock_event_device *c = dev_id;

	/* Disarm the compare/match, signal the event. */
	OIER &= ~OIER_E0;
	OSSR = OSSR_M0;
	c->event_handler(c);

	return IRQ_HANDLED;
}

static int
sa1100_osmr0_set_next_event(unsigned long delta, struct clock_event_device *c)
{
	unsigned long next, oscr;

	OIER |= OIER_E0;
	next = OSCR + delta;
	OSMR0 = next;
	oscr = OSCR;

	return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
}

static void
sa1100_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *c)
{
	switch (mode) {
	case CLOCK_EVT_MODE_ONESHOT:
	case CLOCK_EVT_MODE_UNUSED:
	case CLOCK_EVT_MODE_SHUTDOWN:
		OIER &= ~OIER_E0;
		OSSR = OSSR_M0;
		break;

	case CLOCK_EVT_MODE_RESUME:
	case CLOCK_EVT_MODE_PERIODIC:
		break;
	}
}

static struct clock_event_device ckevt_sa1100_osmr0 = {
	.name		= "osmr0",
	.features	= CLOCK_EVT_FEAT_ONESHOT,
	.rating		= 200,
	.set_next_event	= sa1100_osmr0_set_next_event,
	.set_mode	= sa1100_osmr0_set_mode,
};

static cycle_t sa1100_read_oscr(struct clocksource *s)
{
	return OSCR;
}

static struct clocksource cksrc_sa1100_oscr = {
	.name		= "oscr",
	.rating		= 200,
	.read		= sa1100_read_oscr,
	.mask		= CLOCKSOURCE_MASK(32),
	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
};

static struct irqaction sa1100_timer_irq = {
	.name		= "ost0",
	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
	.handler	= sa1100_ost0_interrupt,
	.dev_id		= &ckevt_sa1100_osmr0,
};

static void __init sa1100_timer_init(void)
{
	OIER = 0;
	OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3;

	init_fixed_sched_clock(&cd, sa1100_update_sched_clock, 32,
			       3686400, SC_MULT, SC_SHIFT);

	clockevents_calc_mult_shift(&ckevt_sa1100_osmr0, 3686400, 4);
	ckevt_sa1100_osmr0.max_delta_ns =
		clockevent_delta2ns(0x7fffffff, &ckevt_sa1100_osmr0);
	ckevt_sa1100_osmr0.min_delta_ns =
		clockevent_delta2ns(MIN_OSCR_DELTA * 2, &ckevt_sa1100_osmr0) + 1;
	ckevt_sa1100_osmr0.cpumask = cpumask_of(0);

	setup_irq(IRQ_OST0, &sa1100_timer_irq);

	clocksource_register_hz(&cksrc_sa1100_oscr, CLOCK_TICK_RATE);
	clockevents_register_device(&ckevt_sa1100_osmr0);
}

#ifdef CONFIG_PM
unsigned long osmr[4], oier;

static void sa1100_timer_suspend(void)
{
	osmr[0] = OSMR0;
	osmr[1] = OSMR1;
	osmr[2] = OSMR2;
	osmr[3] = OSMR3;
	oier = OIER;
}

static void sa1100_timer_resume(void)
{
	OSSR = 0x0f;
	OSMR0 = osmr[0];
	OSMR1 = osmr[1];
	OSMR2 = osmr[2];
	OSMR3 = osmr[3];
	OIER = oier;

	/*
	 * OSMR0 is the system timer: make sure OSCR is sufficiently behind
	 */
	OSCR = OSMR0 - LATCH;
}
#else
#define sa1100_timer_suspend NULL
#define sa1100_timer_resume NULL
#endif

struct sys_timer sa1100_timer = {
	.init		= sa1100_timer_init,
	.suspend	= sa1100_timer_suspend,
	.resume		= sa1100_timer_resume,
};