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ee4af569 SA |
1 | /* |
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 | ||
ee4af569 SA |
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 | ||
32 | #include <asm/sched_clock.h> | |
33 | #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 | ||
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; | |
48 | }; | |
49 | ||
50 | static void __iomem *system_clock __read_mostly; | |
51 | ||
52 | static u32 notrace bcm2835_sched_read(void) | |
53 | { | |
54 | return readl_relaxed(system_clock); | |
55 | } | |
56 | ||
57 | static void bcm2835_time_set_mode(enum clock_event_mode mode, | |
58 | struct clock_event_device *evt_dev) | |
59 | { | |
60 | switch (mode) { | |
61 | case CLOCK_EVT_MODE_ONESHOT: | |
62 | case CLOCK_EVT_MODE_UNUSED: | |
63 | case CLOCK_EVT_MODE_SHUTDOWN: | |
64 | case CLOCK_EVT_MODE_RESUME: | |
65 | break; | |
66 | default: | |
67 | WARN(1, "%s: unhandled event mode %d\n", __func__, mode); | |
68 | break; | |
69 | } | |
70 | } | |
71 | ||
72 | static int bcm2835_time_set_next_event(unsigned long event, | |
73 | struct clock_event_device *evt_dev) | |
74 | { | |
75 | struct bcm2835_timer *timer = container_of(evt_dev, | |
76 | struct bcm2835_timer, evt); | |
77 | writel_relaxed(readl_relaxed(system_clock) + event, | |
78 | timer->compare); | |
79 | return 0; | |
80 | } | |
81 | ||
82 | static irqreturn_t bcm2835_time_interrupt(int irq, void *dev_id) | |
83 | { | |
84 | struct bcm2835_timer *timer = dev_id; | |
85 | void (*event_handler)(struct clock_event_device *); | |
86 | if (readl_relaxed(timer->control) & timer->match_mask) { | |
87 | writel_relaxed(timer->match_mask, timer->control); | |
88 | ||
89 | event_handler = ACCESS_ONCE(timer->evt.event_handler); | |
90 | if (event_handler) | |
91 | event_handler(&timer->evt); | |
92 | return IRQ_HANDLED; | |
93 | } else { | |
94 | return IRQ_NONE; | |
95 | } | |
96 | } | |
97 | ||
98 | static struct of_device_id bcm2835_time_match[] __initconst = { | |
99 | { .compatible = "brcm,bcm2835-system-timer" }, | |
100 | {} | |
101 | }; | |
102 | ||
c1b724f6 | 103 | static void __init bcm2835_timer_init(void) |
ee4af569 SA |
104 | { |
105 | struct device_node *node; | |
106 | void __iomem *base; | |
107 | u32 freq; | |
108 | int irq; | |
109 | struct bcm2835_timer *timer; | |
110 | ||
111 | node = of_find_matching_node(NULL, bcm2835_time_match); | |
112 | if (!node) | |
113 | panic("No bcm2835 timer node"); | |
114 | ||
115 | base = of_iomap(node, 0); | |
116 | if (!base) | |
117 | panic("Can't remap registers"); | |
118 | ||
119 | if (of_property_read_u32(node, "clock-frequency", &freq)) | |
120 | panic("Can't read clock-frequency"); | |
121 | ||
122 | system_clock = base + REG_COUNTER_LO; | |
123 | setup_sched_clock(bcm2835_sched_read, 32, freq); | |
124 | ||
125 | clocksource_mmio_init(base + REG_COUNTER_LO, node->name, | |
126 | freq, 300, 32, clocksource_mmio_readl_up); | |
127 | ||
128 | irq = irq_of_parse_and_map(node, DEFAULT_TIMER); | |
129 | if (irq <= 0) | |
130 | panic("Can't parse IRQ"); | |
131 | ||
132 | timer = kzalloc(sizeof(*timer), GFP_KERNEL); | |
133 | if (!timer) | |
134 | panic("Can't allocate timer struct\n"); | |
135 | ||
136 | timer->control = base + REG_CONTROL; | |
137 | timer->compare = base + REG_COMPARE(DEFAULT_TIMER); | |
138 | timer->match_mask = BIT(DEFAULT_TIMER); | |
139 | timer->evt.name = node->name; | |
140 | timer->evt.rating = 300; | |
141 | timer->evt.features = CLOCK_EVT_FEAT_ONESHOT; | |
142 | timer->evt.set_mode = bcm2835_time_set_mode; | |
143 | timer->evt.set_next_event = bcm2835_time_set_next_event; | |
144 | timer->evt.cpumask = cpumask_of(0); | |
145 | timer->act.name = node->name; | |
146 | timer->act.flags = IRQF_TIMER | IRQF_SHARED; | |
147 | timer->act.dev_id = timer; | |
148 | timer->act.handler = bcm2835_time_interrupt; | |
149 | ||
150 | if (setup_irq(irq, &timer->act)) | |
151 | panic("Can't set up timer IRQ\n"); | |
152 | ||
153 | clockevents_config_and_register(&timer->evt, freq, 0xf, 0xffffffff); | |
154 | ||
155 | pr_info("bcm2835: system timer (irq = %d)\n", irq); | |
156 | } | |
c1b724f6 SW |
157 | CLOCKSOURCE_OF_DECLARE(bcm2835, "brcm,bcm2835-system-timer", |
158 | bcm2835_timer_init); |