blob: bc19f12c20ced747eb2afa33f5e918ab97f8a42c [file] [log] [blame]
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
19#include <linux/bcm2835_timer.h>
20#include <linux/bitops.h>
21#include <linux/clockchips.h>
22#include <linux/clocksource.h>
23#include <linux/interrupt.h>
24#include <linux/irqreturn.h>
25#include <linux/kernel.h>
26#include <linux/module.h>
27#include <linux/of_address.h>
28#include <linux/of_irq.h>
29#include <linux/of_platform.h>
30#include <linux/slab.h>
31#include <linux/string.h>
32
33#include <asm/sched_clock.h>
34#include <asm/irq.h>
35
36#define REG_CONTROL 0x00
37#define REG_COUNTER_LO 0x04
38#define REG_COUNTER_HI 0x08
39#define REG_COMPARE(n) (0x0c + (n) * 4)
40#define MAX_TIMER 3
41#define DEFAULT_TIMER 3
42
43struct bcm2835_timer {
44 void __iomem *control;
45 void __iomem *compare;
46 int match_mask;
47 struct clock_event_device evt;
48 struct irqaction act;
49};
50
51static void __iomem *system_clock __read_mostly;
52
53static u32 notrace bcm2835_sched_read(void)
54{
55 return readl_relaxed(system_clock);
56}
57
58static void bcm2835_time_set_mode(enum clock_event_mode mode,
59 struct clock_event_device *evt_dev)
60{
61 switch (mode) {
62 case CLOCK_EVT_MODE_ONESHOT:
63 case CLOCK_EVT_MODE_UNUSED:
64 case CLOCK_EVT_MODE_SHUTDOWN:
65 case CLOCK_EVT_MODE_RESUME:
66 break;
67 default:
68 WARN(1, "%s: unhandled event mode %d\n", __func__, mode);
69 break;
70 }
71}
72
73static int bcm2835_time_set_next_event(unsigned long event,
74 struct clock_event_device *evt_dev)
75{
76 struct bcm2835_timer *timer = container_of(evt_dev,
77 struct bcm2835_timer, evt);
78 writel_relaxed(readl_relaxed(system_clock) + event,
79 timer->compare);
80 return 0;
81}
82
83static irqreturn_t bcm2835_time_interrupt(int irq, void *dev_id)
84{
85 struct bcm2835_timer *timer = dev_id;
86 void (*event_handler)(struct clock_event_device *);
87 if (readl_relaxed(timer->control) & timer->match_mask) {
88 writel_relaxed(timer->match_mask, timer->control);
89
90 event_handler = ACCESS_ONCE(timer->evt.event_handler);
91 if (event_handler)
92 event_handler(&timer->evt);
93 return IRQ_HANDLED;
94 } else {
95 return IRQ_NONE;
96 }
97}
98
99static struct of_device_id bcm2835_time_match[] __initconst = {
100 { .compatible = "brcm,bcm2835-system-timer" },
101 {}
102};
103
104static void __init bcm2835_time_init(void)
105{
106 struct device_node *node;
107 void __iomem *base;
108 u32 freq;
109 int irq;
110 struct bcm2835_timer *timer;
111
112 node = of_find_matching_node(NULL, bcm2835_time_match);
113 if (!node)
114 panic("No bcm2835 timer node");
115
116 base = of_iomap(node, 0);
117 if (!base)
118 panic("Can't remap registers");
119
120 if (of_property_read_u32(node, "clock-frequency", &freq))
121 panic("Can't read clock-frequency");
122
123 system_clock = base + REG_COUNTER_LO;
124 setup_sched_clock(bcm2835_sched_read, 32, freq);
125
126 clocksource_mmio_init(base + REG_COUNTER_LO, node->name,
127 freq, 300, 32, clocksource_mmio_readl_up);
128
129 irq = irq_of_parse_and_map(node, DEFAULT_TIMER);
130 if (irq <= 0)
131 panic("Can't parse IRQ");
132
133 timer = kzalloc(sizeof(*timer), GFP_KERNEL);
134 if (!timer)
135 panic("Can't allocate timer struct\n");
136
137 timer->control = base + REG_CONTROL;
138 timer->compare = base + REG_COMPARE(DEFAULT_TIMER);
139 timer->match_mask = BIT(DEFAULT_TIMER);
140 timer->evt.name = node->name;
141 timer->evt.rating = 300;
142 timer->evt.features = CLOCK_EVT_FEAT_ONESHOT;
143 timer->evt.set_mode = bcm2835_time_set_mode;
144 timer->evt.set_next_event = bcm2835_time_set_next_event;
145 timer->evt.cpumask = cpumask_of(0);
146 timer->act.name = node->name;
147 timer->act.flags = IRQF_TIMER | IRQF_SHARED;
148 timer->act.dev_id = timer;
149 timer->act.handler = bcm2835_time_interrupt;
150
151 if (setup_irq(irq, &timer->act))
152 panic("Can't set up timer IRQ\n");
153
154 clockevents_config_and_register(&timer->evt, freq, 0xf, 0xffffffff);
155
156 pr_info("bcm2835: system timer (irq = %d)\n", irq);
157}
158
159struct sys_timer bcm2835_timer = {
160 .init = bcm2835_time_init,
161};