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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
45#define TIMER_CTRL_VAL 0x0020
46#define TIMER_AS_VAL 0x0024
47#define TIMER_COUNT_R_ACTIVE (1 << 5)
48#define TIMER_COUNT_W_ACTIVE (1 << 4)
49#define TIMER_MATCH_W_ACTIVE (1 << 0)
50
51#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
52
53static void __iomem *regbase;
54
55static 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
65static 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
73static 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
91static 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
108static 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
116static 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
125static 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
132static void __init vt8500_timer_init(struct device_node *np)
133{
134 int timer_irq;
135
136 regbase = of_iomap(np, 0);
137 if (!regbase) {
138 pr_err("%s: Missing iobase description in Device Tree\n",
139 __func__);
140 of_node_put(np);
141 return;
142 }
143 timer_irq = irq_of_parse_and_map(np, 0);
144 if (!timer_irq) {
145 pr_err("%s: Missing irq description in Device Tree\n",
146 __func__);
147 of_node_put(np);
148 return;
149 }
150
151 writel(1, regbase + TIMER_CTRL_VAL);
152 writel(0xf, regbase + TIMER_STATUS_VAL);
153 writel(~0, regbase + TIMER_MATCH_VAL);
154
155 if (clocksource_register_hz(&clocksource, VT8500_TIMER_HZ))
156 pr_err("%s: vt8500_timer_init: clocksource_register failed for %s\n",
157 __func__, clocksource.name);
158
159 clockevent.cpumask = cpumask_of(0);
160
161 if (setup_irq(timer_irq, &irq))
162 pr_err("%s: setup_irq failed for %s\n", __func__,
163 clockevent.name);
164 clockevents_config_and_register(&clockevent, VT8500_TIMER_HZ,
165 4, 0xf0000000);
166}
167
168CLOCKSOURCE_OF_DECLARE(vt8500, "via,vt8500-timer", vt8500_timer_init);
169
