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Simon Arlottee4af562012-09-10 22:38:35 -06001/*
2 * Copyright 2012 Simon Arlott
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17 */
18
Simon Arlottee4af562012-09-10 22:38:35 -060019#include <linux/bitops.h>
20#include <linux/clockchips.h>
21#include <linux/clocksource.h>
22#include <linux/interrupt.h>
23#include <linux/irqreturn.h>
24#include <linux/kernel.h>
25#include <linux/module.h>
26#include <linux/of_address.h>
27#include <linux/of_irq.h>
28#include <linux/of_platform.h>
29#include <linux/slab.h>
30#include <linux/string.h>
Stephen Boyd38ff87f2013-06-01 23:39:40 -070031#include <linux/sched_clock.h>
Simon Arlottee4af562012-09-10 22:38:35 -060032
Simon Arlottee4af562012-09-10 22:38:35 -060033#include <asm/irq.h>
34
35#define REG_CONTROL 0x00
36#define REG_COUNTER_LO 0x04
37#define REG_COUNTER_HI 0x08
38#define REG_COMPARE(n) (0x0c + (n) * 4)
39#define MAX_TIMER 3
40#define DEFAULT_TIMER 3
41
42struct bcm2835_timer {
43 void __iomem *control;
44 void __iomem *compare;
45 int match_mask;
46 struct clock_event_device evt;
47 struct irqaction act;
48};
49
50static void __iomem *system_clock __read_mostly;
51
Stephen Boyd18952f22013-07-18 16:21:20 -070052static u64 notrace bcm2835_sched_read(void)
Simon Arlottee4af562012-09-10 22:38:35 -060053{
54 return readl_relaxed(system_clock);
55}
56
Simon Arlottee4af562012-09-10 22:38:35 -060057static int bcm2835_time_set_next_event(unsigned long event,
58 struct clock_event_device *evt_dev)
59{
60 struct bcm2835_timer *timer = container_of(evt_dev,
61 struct bcm2835_timer, evt);
62 writel_relaxed(readl_relaxed(system_clock) + event,
63 timer->compare);
64 return 0;
65}
66
67static irqreturn_t bcm2835_time_interrupt(int irq, void *dev_id)
68{
69 struct bcm2835_timer *timer = dev_id;
70 void (*event_handler)(struct clock_event_device *);
71 if (readl_relaxed(timer->control) & timer->match_mask) {
72 writel_relaxed(timer->match_mask, timer->control);
73
74 event_handler = ACCESS_ONCE(timer->evt.event_handler);
75 if (event_handler)
76 event_handler(&timer->evt);
77 return IRQ_HANDLED;
78 } else {
79 return IRQ_NONE;
80 }
81}
82
Rob Herringeffbfdd2013-02-06 14:40:22 -060083static void __init bcm2835_timer_init(struct device_node *node)
Simon Arlottee4af562012-09-10 22:38:35 -060084{
Simon Arlottee4af562012-09-10 22:38:35 -060085 void __iomem *base;
86 u32 freq;
87 int irq;
88 struct bcm2835_timer *timer;
89
Simon Arlottee4af562012-09-10 22:38:35 -060090 base = of_iomap(node, 0);
91 if (!base)
92 panic("Can't remap registers");
93
94 if (of_property_read_u32(node, "clock-frequency", &freq))
95 panic("Can't read clock-frequency");
96
97 system_clock = base + REG_COUNTER_LO;
Stephen Boyd18952f22013-07-18 16:21:20 -070098 sched_clock_register(bcm2835_sched_read, 32, freq);
Simon Arlottee4af562012-09-10 22:38:35 -060099
100 clocksource_mmio_init(base + REG_COUNTER_LO, node->name,
101 freq, 300, 32, clocksource_mmio_readl_up);
102
103 irq = irq_of_parse_and_map(node, DEFAULT_TIMER);
104 if (irq <= 0)
105 panic("Can't parse IRQ");
106
107 timer = kzalloc(sizeof(*timer), GFP_KERNEL);
108 if (!timer)
109 panic("Can't allocate timer struct\n");
110
111 timer->control = base + REG_CONTROL;
112 timer->compare = base + REG_COMPARE(DEFAULT_TIMER);
113 timer->match_mask = BIT(DEFAULT_TIMER);
114 timer->evt.name = node->name;
115 timer->evt.rating = 300;
116 timer->evt.features = CLOCK_EVT_FEAT_ONESHOT;
Simon Arlottee4af562012-09-10 22:38:35 -0600117 timer->evt.set_next_event = bcm2835_time_set_next_event;
118 timer->evt.cpumask = cpumask_of(0);
119 timer->act.name = node->name;
120 timer->act.flags = IRQF_TIMER | IRQF_SHARED;
121 timer->act.dev_id = timer;
122 timer->act.handler = bcm2835_time_interrupt;
123
124 if (setup_irq(irq, &timer->act))
125 panic("Can't set up timer IRQ\n");
126
127 clockevents_config_and_register(&timer->evt, freq, 0xf, 0xffffffff);
128
129 pr_info("bcm2835: system timer (irq = %d)\n", irq);
130}
Stephen Warrenc1b724f2013-01-03 20:23:13 -0700131CLOCKSOURCE_OF_DECLARE(bcm2835, "brcm,bcm2835-system-timer",
132 bcm2835_timer_init);