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1 | /* |
2 | * arch/arm/mach-vt8500/timer.c |
3 | * |
4 | * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz> |
5 | * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com> |
6 | * |
7 | * This program is free software; you can redistribute it and/or modify |
8 | * it under the terms of the GNU General Public License as published by |
9 | * the Free Software Foundation; either version 2 of the License, or |
10 | * (at your option) any later version. |
11 | * |
12 | * This program is distributed in the hope that it will be useful, |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
15 | * GNU General Public License for more details. |
16 | * |
17 | * You should have received a copy of the GNU General Public License |
18 | * along with this program; if not, write to the Free Software |
19 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
20 | */ |
21 | |
22 | /* |
23 | * This file is copied and modified from the original timer.c provided by |
24 | * Alexey Charkov. Minor changes have been made for Device Tree Support. |
25 | */ |
26 | |
27 | #include <linux/io.h> |
28 | #include <linux/irq.h> |
29 | #include <linux/interrupt.h> |
30 | #include <linux/clocksource.h> |
31 | #include <linux/clockchips.h> |
32 | #include <linux/delay.h> |
33 | #include <asm/mach/time.h> |
34 | |
35 | #include <linux/of.h> |
36 | #include <linux/of_address.h> |
37 | #include <linux/of_irq.h> |
38 | |
39 | #define VT8500_TIMER_OFFSET 0x0100 |
40 | #define VT8500_TIMER_HZ 3000000 |
41 | #define TIMER_MATCH_VAL 0x0000 |
42 | #define TIMER_COUNT_VAL 0x0010 |
43 | #define TIMER_STATUS_VAL 0x0014 |
44 | #define TIMER_IER_VAL 0x001c /* interrupt enable */ |
45 | #define TIMER_CTRL_VAL 0x0020 |
46 | #define TIMER_AS_VAL 0x0024 /* access status */ |
47 | #define TIMER_COUNT_R_ACTIVE (1 << 5) /* not ready for read */ |
48 | #define TIMER_COUNT_W_ACTIVE (1 << 4) /* not ready for write */ |
49 | #define TIMER_MATCH_W_ACTIVE (1 << 0) /* not ready for write */ |
50 | |
51 | #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t) |
52 | |
53 | static void __iomem *regbase; |
54 | |
55 | static cycle_t vt8500_timer_read(struct clocksource *cs) |
56 | { |
57 | int loops = msecs_to_loops(10); |
58 | writel(3, regbase + TIMER_CTRL_VAL); |
59 | while ((readl((regbase + TIMER_AS_VAL)) & TIMER_COUNT_R_ACTIVE) |
60 | && --loops) |
61 | cpu_relax(); |
62 | return readl(regbase + TIMER_COUNT_VAL); |
63 | } |
64 | |
65 | static struct clocksource clocksource = { |
66 | .name = "vt8500_timer", |
67 | .rating = 200, |
68 | .read = vt8500_timer_read, |
69 | .mask = CLOCKSOURCE_MASK(32), |
70 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, |
71 | }; |
72 | |
73 | static int vt8500_timer_set_next_event(unsigned long cycles, |
74 | struct clock_event_device *evt) |
75 | { |
76 | int loops = msecs_to_loops(10); |
77 | cycle_t alarm = clocksource.read(&clocksource) + cycles; |
78 | while ((readl(regbase + TIMER_AS_VAL) & TIMER_MATCH_W_ACTIVE) |
79 | && --loops) |
80 | cpu_relax(); |
81 | writel((unsigned long)alarm, regbase + TIMER_MATCH_VAL); |
82 | |
83 | if ((signed)(alarm - clocksource.read(&clocksource)) <= 16) |
84 | return -ETIME; |
85 | |
86 | writel(1, regbase + TIMER_IER_VAL); |
87 | |
88 | return 0; |
89 | } |
90 | |
91 | static void vt8500_timer_set_mode(enum clock_event_mode mode, |
92 | struct clock_event_device *evt) |
93 | { |
94 | switch (mode) { |
95 | case CLOCK_EVT_MODE_RESUME: |
96 | case CLOCK_EVT_MODE_PERIODIC: |
97 | break; |
98 | case CLOCK_EVT_MODE_ONESHOT: |
99 | case CLOCK_EVT_MODE_UNUSED: |
100 | case CLOCK_EVT_MODE_SHUTDOWN: |
101 | writel(readl(regbase + TIMER_CTRL_VAL) | 1, |
102 | regbase + TIMER_CTRL_VAL); |
103 | writel(0, regbase + TIMER_IER_VAL); |
104 | break; |
105 | } |
106 | } |
107 | |
108 | static struct clock_event_device clockevent = { |
109 | .name = "vt8500_timer", |
110 | .features = CLOCK_EVT_FEAT_ONESHOT, |
111 | .rating = 200, |
112 | .set_next_event = vt8500_timer_set_next_event, |
113 | .set_mode = vt8500_timer_set_mode, |
114 | }; |
115 | |
116 | static irqreturn_t vt8500_timer_interrupt(int irq, void *dev_id) |
117 | { |
118 | struct clock_event_device *evt = dev_id; |
119 | writel(0xf, regbase + TIMER_STATUS_VAL); |
120 | evt->event_handler(evt); |
121 | |
122 | return IRQ_HANDLED; |
123 | } |
124 | |
125 | static struct irqaction irq = { |
126 | .name = "vt8500_timer", |
127 | .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, |
128 | .handler = vt8500_timer_interrupt, |
129 | .dev_id = &clockevent, |
130 | }; |
131 | |
132 | static struct of_device_id vt8500_timer_ids[] = { |
133 | { .compatible = "via,vt8500-timer" }, |
134 | { } |
135 | }; |
136 | |
137 | static void __init vt8500_timer_init(void) |
138 | { |
139 | struct device_node *np; |
140 | int timer_irq; |
141 | |
142 | np = of_find_matching_node(NULL, vt8500_timer_ids); |
143 | if (!np) { |
144 | pr_err("%s: Timer description missing from Device Tree\n", |
145 | __func__); |
146 | return; |
147 | } |
148 | regbase = of_iomap(np, 0); |
149 | if (!regbase) { |
150 | pr_err("%s: Missing iobase description in Device Tree\n", |
151 | __func__); |
152 | of_node_put(np); |
153 | return; |
154 | } |
155 | timer_irq = irq_of_parse_and_map(np, 0); |
156 | if (!timer_irq) { |
157 | pr_err("%s: Missing irq description in Device Tree\n", |
158 | __func__); |
159 | of_node_put(np); |
160 | return; |
161 | } |
162 | |
163 | writel(1, regbase + TIMER_CTRL_VAL); |
164 | writel(0xf, regbase + TIMER_STATUS_VAL); |
165 | writel(~0, regbase + TIMER_MATCH_VAL); |
166 | |
167 | if (clocksource_register_hz(&clocksource, VT8500_TIMER_HZ)) |
168 | pr_err("%s: vt8500_timer_init: clocksource_register failed for %s\n", |
169 | __func__, clocksource.name); |
170 | |
171 | clockevent.cpumask = cpumask_of(0); |
172 | |
173 | if (setup_irq(timer_irq, &irq)) |
174 | pr_err("%s: setup_irq failed for %s\n", __func__, |
175 | clockevent.name); |
176 | clockevents_config_and_register(&clockevent, VT8500_TIMER_HZ, |
177 | 4, 0xf0000000); |
178 | } |
179 | |
180 | CLOCKSOURCE_OF_DECLARE(vt8500, "via,vt8500-timer", vt8500_timer_init) |
181 |
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