Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: 2b196cbfadb625796078a0973e8c53dd39956d4d (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
// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright 2012 Simon Arlott
 */

#include <linux/bitops.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/interrupt.h>
#include <linux/irqreturn.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/sched_clock.h>

#include <asm/irq.h>

#define REG_CONTROL	0x00
#define REG_COUNTER_LO	0x04
#define REG_COUNTER_HI	0x08
#define REG_COMPARE(n)	(0x0c + (n) * 4)
#define MAX_TIMER	3
#define DEFAULT_TIMER	3

struct bcm2835_timer {
	void __iomem *control;
	void __iomem *compare;
	int match_mask;
	struct clock_event_device evt;
	struct irqaction act;
};

static void __iomem *system_clock __read_mostly;

static u64 notrace bcm2835_sched_read(void)
{
	return readl_relaxed(system_clock);
}

static int bcm2835_time_set_next_event(unsigned long event,
	struct clock_event_device *evt_dev)
{
	struct bcm2835_timer *timer = container_of(evt_dev,
		struct bcm2835_timer, evt);
	writel_relaxed(readl_relaxed(system_clock) + event,
		timer->compare);
	return 0;
}

static irqreturn_t bcm2835_time_interrupt(int irq, void *dev_id)
{
	struct bcm2835_timer *timer = dev_id;
	void (*event_handler)(struct clock_event_device *);
	if (readl_relaxed(timer->control) & timer->match_mask) {
		writel_relaxed(timer->match_mask, timer->control);

		event_handler = READ_ONCE(timer->evt.event_handler);
		if (event_handler)
			event_handler(&timer->evt);
		return IRQ_HANDLED;
	} else {
		return IRQ_NONE;
	}
}

static int __init bcm2835_timer_init(struct device_node *node)
{
	void __iomem *base;
	u32 freq;
	int irq, ret;
	struct bcm2835_timer *timer;

	base = of_iomap(node, 0);
	if (!base) {
		pr_err("Can't remap registers\n");
		return -ENXIO;
	}

	ret = of_property_read_u32(node, "clock-frequency", &freq);
	if (ret) {
		pr_err("Can't read clock-frequency\n");
		goto err_iounmap;
	}

	system_clock = base + REG_COUNTER_LO;
	sched_clock_register(bcm2835_sched_read, 32, freq);

	clocksource_mmio_init(base + REG_COUNTER_LO, node->name,
		freq, 300, 32, clocksource_mmio_readl_up);

	irq = irq_of_parse_and_map(node, DEFAULT_TIMER);
	if (irq <= 0) {
		pr_err("Can't parse IRQ\n");
		ret = -EINVAL;
		goto err_iounmap;
	}

	timer = kzalloc(sizeof(*timer), GFP_KERNEL);
	if (!timer) {
		ret = -ENOMEM;
		goto err_iounmap;
	}

	timer->control = base + REG_CONTROL;
	timer->compare = base + REG_COMPARE(DEFAULT_TIMER);
	timer->match_mask = BIT(DEFAULT_TIMER);
	timer->evt.name = node->name;
	timer->evt.rating = 300;
	timer->evt.features = CLOCK_EVT_FEAT_ONESHOT;
	timer->evt.set_next_event = bcm2835_time_set_next_event;
	timer->evt.cpumask = cpumask_of(0);
	timer->act.name = node->name;
	timer->act.flags = IRQF_TIMER | IRQF_SHARED;
	timer->act.dev_id = timer;
	timer->act.handler = bcm2835_time_interrupt;

	ret = setup_irq(irq, &timer->act);
	if (ret) {
		pr_err("Can't set up timer IRQ\n");
		goto err_iounmap;
	}

	clockevents_config_and_register(&timer->evt, freq, 0xf, 0xffffffff);

	pr_info("bcm2835: system timer (irq = %d)\n", irq);

	return 0;

err_iounmap:
	iounmap(base);
	return ret;
}
TIMER_OF_DECLARE(bcm2835, "brcm,bcm2835-system-timer",
			bcm2835_timer_init);