x86/mm/pat: Don't report PAT on CPUs that don't support it
[linux/fpc-iii.git] / drivers / clocksource / bcm2835_timer.c
blobf2f29d2be1cf43cf91536998ea4a3b27828490b6
1 /*
2 * Copyright 2012 Simon Arlott
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.
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.
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
19 #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>
31 #include <linux/sched_clock.h>
33 #include <asm/irq.h>
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
42 struct bcm2835_timer {
43 void __iomem *control;
44 void __iomem *compare;
45 int match_mask;
46 struct clock_event_device evt;
47 struct irqaction act;
50 static void __iomem *system_clock __read_mostly;
52 static u64 notrace bcm2835_sched_read(void)
54 return readl_relaxed(system_clock);
57 static int bcm2835_time_set_next_event(unsigned long event,
58 struct clock_event_device *evt_dev)
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;
67 static irqreturn_t bcm2835_time_interrupt(int irq, void *dev_id)
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);
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;
83 static int __init bcm2835_timer_init(struct device_node *node)
85 void __iomem *base;
86 u32 freq;
87 int irq, ret;
88 struct bcm2835_timer *timer;
90 base = of_iomap(node, 0);
91 if (!base) {
92 pr_err("Can't remap registers");
93 return -ENXIO;
96 ret = of_property_read_u32(node, "clock-frequency", &freq);
97 if (ret) {
98 pr_err("Can't read clock-frequency");
99 goto err_iounmap;
102 system_clock = base + REG_COUNTER_LO;
103 sched_clock_register(bcm2835_sched_read, 32, freq);
105 clocksource_mmio_init(base + REG_COUNTER_LO, node->name,
106 freq, 300, 32, clocksource_mmio_readl_up);
108 irq = irq_of_parse_and_map(node, DEFAULT_TIMER);
109 if (irq <= 0) {
110 pr_err("Can't parse IRQ");
111 ret = -EINVAL;
112 goto err_iounmap;
115 timer = kzalloc(sizeof(*timer), GFP_KERNEL);
116 if (!timer) {
117 pr_err("Can't allocate timer struct\n");
118 ret = -ENOMEM;
119 goto err_iounmap;
122 timer->control = base + REG_CONTROL;
123 timer->compare = base + REG_COMPARE(DEFAULT_TIMER);
124 timer->match_mask = BIT(DEFAULT_TIMER);
125 timer->evt.name = node->name;
126 timer->evt.rating = 300;
127 timer->evt.features = CLOCK_EVT_FEAT_ONESHOT;
128 timer->evt.set_next_event = bcm2835_time_set_next_event;
129 timer->evt.cpumask = cpumask_of(0);
130 timer->act.name = node->name;
131 timer->act.flags = IRQF_TIMER | IRQF_SHARED;
132 timer->act.dev_id = timer;
133 timer->act.handler = bcm2835_time_interrupt;
135 ret = setup_irq(irq, &timer->act);
136 if (ret) {
137 pr_err("Can't set up timer IRQ\n");
138 goto err_iounmap;
141 clockevents_config_and_register(&timer->evt, freq, 0xf, 0xffffffff);
143 pr_info("bcm2835: system timer (irq = %d)\n", irq);
145 return 0;
147 err_iounmap:
148 iounmap(base);
149 return ret;
151 CLOCKSOURCE_OF_DECLARE(bcm2835, "brcm,bcm2835-system-timer",
152 bcm2835_timer_init);