1 /*
2 * Copyright (C) 2004-2007 Atmel Corporation
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 version 2 as
6 * published by the Free Software Foundation.
7 */
8 #include <linux/clk.h>
9 #include <linux/clockchips.h>
10 #include <linux/init.h>
11 #include <linux/interrupt.h>
12 #include <linux/irq.h>
13 #include <linux/kernel.h>
14 #include <linux/time.h>
15
16 #include <asm/sysreg.h>
17
18 #include <mach/pm.h>
19
20
read_cycle_count(struct clocksource * cs)21 static cycle_t read_cycle_count(struct clocksource *cs)
22 {
23 return (cycle_t)sysreg_read(COUNT);
24 }
25
26 /*
27 * The architectural cycle count registers are a fine clocksource unless
28 * the system idle loop use sleep states like "idle": the CPU cycles
29 * measured by COUNT (and COMPARE) don't happen during sleep states.
30 * Their duration also changes if cpufreq changes the CPU clock rate.
31 * So we rate the clocksource using COUNT as very low quality.
32 */
33 static struct clocksource counter = {
34 .name = "avr32_counter",
35 .rating = 50,
36 .read = read_cycle_count,
37 .mask = CLOCKSOURCE_MASK(32),
38 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
39 };
40
timer_interrupt(int irq,void * dev_id)41 static irqreturn_t timer_interrupt(int irq, void *dev_id)
42 {
43 struct clock_event_device *evdev = dev_id;
44
45 if (unlikely(!(intc_get_pending(0) & 1)))
46 return IRQ_NONE;
47
48 /*
49 * Disable the interrupt until the clockevent subsystem
50 * reprograms it.
51 */
52 sysreg_write(COMPARE, 0);
53
54 evdev->event_handler(evdev);
55 return IRQ_HANDLED;
56 }
57
58 static struct irqaction timer_irqaction = {
59 .handler = timer_interrupt,
60 /* Oprofile uses the same irq as the timer, so allow it to be shared */
61 .flags = IRQF_TIMER | IRQF_DISABLED | IRQF_SHARED,
62 .name = "avr32_comparator",
63 };
64
comparator_next_event(unsigned long delta,struct clock_event_device * evdev)65 static int comparator_next_event(unsigned long delta,
66 struct clock_event_device *evdev)
67 {
68 unsigned long flags;
69
70 raw_local_irq_save(flags);
71
72 /* The time to read COUNT then update COMPARE must be less
73 * than the min_delta_ns value for this clockevent source.
74 */
75 sysreg_write(COMPARE, (sysreg_read(COUNT) + delta) ? : 1);
76
77 raw_local_irq_restore(flags);
78
79 return 0;
80 }
81
comparator_mode(enum clock_event_mode mode,struct clock_event_device * evdev)82 static void comparator_mode(enum clock_event_mode mode,
83 struct clock_event_device *evdev)
84 {
85 switch (mode) {
86 case CLOCK_EVT_MODE_ONESHOT:
87 pr_debug("%s: start\n", evdev->name);
88 /* FALLTHROUGH */
89 case CLOCK_EVT_MODE_RESUME:
90 cpu_disable_idle_sleep();
91 break;
92 case CLOCK_EVT_MODE_UNUSED:
93 case CLOCK_EVT_MODE_SHUTDOWN:
94 sysreg_write(COMPARE, 0);
95 pr_debug("%s: stop\n", evdev->name);
96 cpu_enable_idle_sleep();
97 break;
98 default:
99 BUG();
100 }
101 }
102
103 static struct clock_event_device comparator = {
104 .name = "avr32_comparator",
105 .features = CLOCK_EVT_FEAT_ONESHOT,
106 .shift = 16,
107 .rating = 50,
108 .set_next_event = comparator_next_event,
109 .set_mode = comparator_mode,
110 };
111
read_persistent_clock(struct timespec * ts)112 void read_persistent_clock(struct timespec *ts)
113 {
114 ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0);
115 ts->tv_nsec = 0;
116 }
117
time_init(void)118 void __init time_init(void)
119 {
120 unsigned long counter_hz;
121 int ret;
122
123 /* figure rate for counter */
124 counter_hz = clk_get_rate(boot_cpu_data.clk);
125 ret = clocksource_register_hz(&counter, counter_hz);
126 if (ret)
127 pr_debug("timer: could not register clocksource: %d\n", ret);
128
129 /* setup COMPARE clockevent */
130 comparator.mult = div_sc(counter_hz, NSEC_PER_SEC, comparator.shift);
131 comparator.max_delta_ns = clockevent_delta2ns((u32)~0, &comparator);
132 comparator.min_delta_ns = clockevent_delta2ns(50, &comparator) + 1;
133 comparator.cpumask = cpumask_of(0);
134
135 sysreg_write(COMPARE, 0);
136 timer_irqaction.dev_id = &comparator;
137
138 ret = setup_irq(0, &timer_irqaction);
139 if (ret)
140 pr_debug("timer: could not request IRQ 0: %d\n", ret);
141 else {
142 clockevents_register_device(&comparator);
143
144 pr_info("%s: irq 0, %lu.%03lu MHz\n", comparator.name,
145 ((counter_hz + 500) / 1000) / 1000,
146 ((counter_hz + 500) / 1000) % 1000);
147 }
148 }
149