aboutsummaryrefslogtreecommitdiff
path: root/arch/arm/mach-sa1100/time.c
blob: 934db6385cd6236a8580ca2358b98e2e2d25ae46 (plain)
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
/*
 * 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/timex.h>
#include <linux/clockchips.h>

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

static u32 notrace sa1100_read_sched_clock(void)
{
	return readl_relaxed(OSCR);
}

#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. */
	writel_relaxed(readl_relaxed(OIER) & ~OIER_E0, OIER);
	writel_relaxed(OSSR_M0, OSSR);
	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;

	writel_relaxed(readl_relaxed(OIER) | OIER_E0, OIER);
	next = readl_relaxed(OSCR) + delta;
	writel_relaxed(next, OSMR0);
	oscr = readl_relaxed(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:
		writel_relaxed(readl_relaxed(OIER) & ~OIER_E0, OIER);
		writel_relaxed(OSSR_M0, OSSR);
		break;

	case CLOCK_EVT_MODE_RESUME:
	case CLOCK_EVT_MODE_PERIODIC:
		break;
	}
}

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

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

static void sa1100_timer_resume(struct clock_event_device *cedev)
{
	writel_relaxed(0x0f, OSSR);
	writel_relaxed(osmr[0], OSMR0);
	writel_relaxed(osmr[1], OSMR1);
	writel_relaxed(osmr[2], OSMR2);
	writel_relaxed(osmr[3], OSMR3);
	writel_relaxed(oier, OIER);

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

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,
	.suspend	= sa1100_timer_suspend,
	.resume		= sa1100_timer_resume,
};

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

void __init sa1100_timer_init(void)
{
	writel_relaxed(0, OIER);
	writel_relaxed(OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3, OSSR);

	setup_sched_clock(sa1100_read_sched_clock, 32, 3686400);

	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_mmio_init(OSCR, "oscr", CLOCK_TICK_RATE, 200, 32,
		clocksource_mmio_readl_up);
	clockevents_register_device(&ckevt_sa1100_osmr0);
}