clocksource: pass clocksource to read() callback
[linux-2.6.git] / arch / avr32 / kernel / time.c
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
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         .shift          = 16,
39         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
40 };
41
42 static irqreturn_t timer_interrupt(int irq, void *dev_id)
43 {
44         struct clock_event_device *evdev = dev_id;
45
46         if (unlikely(!(intc_get_pending(0) & 1)))
47                 return IRQ_NONE;
48
49         /*
50          * Disable the interrupt until the clockevent subsystem
51          * reprograms it.
52          */
53         sysreg_write(COMPARE, 0);
54
55         evdev->event_handler(evdev);
56         return IRQ_HANDLED;
57 }
58
59 static struct irqaction timer_irqaction = {
60         .handler        = timer_interrupt,
61         /* Oprofile uses the same irq as the timer, so allow it to be shared */
62         .flags          = IRQF_TIMER | IRQF_DISABLED | IRQF_SHARED,
63         .name           = "avr32_comparator",
64 };
65
66 static int comparator_next_event(unsigned long delta,
67                 struct clock_event_device *evdev)
68 {
69         unsigned long   flags;
70
71         raw_local_irq_save(flags);
72
73         /* The time to read COUNT then update COMPARE must be less
74          * than the min_delta_ns value for this clockevent source.
75          */
76         sysreg_write(COMPARE, (sysreg_read(COUNT) + delta) ? : 1);
77
78         raw_local_irq_restore(flags);
79
80         return 0;
81 }
82
83 static void comparator_mode(enum clock_event_mode mode,
84                 struct clock_event_device *evdev)
85 {
86         switch (mode) {
87         case CLOCK_EVT_MODE_ONESHOT:
88                 pr_debug("%s: start\n", evdev->name);
89                 /* FALLTHROUGH */
90         case CLOCK_EVT_MODE_RESUME:
91                 cpu_disable_idle_sleep();
92                 break;
93         case CLOCK_EVT_MODE_UNUSED:
94         case CLOCK_EVT_MODE_SHUTDOWN:
95                 sysreg_write(COMPARE, 0);
96                 pr_debug("%s: stop\n", evdev->name);
97                 cpu_enable_idle_sleep();
98                 break;
99         default:
100                 BUG();
101         }
102 }
103
104 static struct clock_event_device comparator = {
105         .name           = "avr32_comparator",
106         .features       = CLOCK_EVT_FEAT_ONESHOT,
107         .shift          = 16,
108         .rating         = 50,
109         .set_next_event = comparator_next_event,
110         .set_mode       = comparator_mode,
111 };
112
113 void __init time_init(void)
114 {
115         unsigned long counter_hz;
116         int ret;
117
118         xtime.tv_sec = mktime(2007, 1, 1, 0, 0, 0);
119         xtime.tv_nsec = 0;
120
121         set_normalized_timespec(&wall_to_monotonic,
122                                 -xtime.tv_sec, -xtime.tv_nsec);
123
124         /* figure rate for counter */
125         counter_hz = clk_get_rate(boot_cpu_data.clk);
126         counter.mult = clocksource_hz2mult(counter_hz, counter.shift);
127
128         ret = clocksource_register(&counter);
129         if (ret)
130                 pr_debug("timer: could not register clocksource: %d\n", ret);
131
132         /* setup COMPARE clockevent */
133         comparator.mult = div_sc(counter_hz, NSEC_PER_SEC, comparator.shift);
134         comparator.max_delta_ns = clockevent_delta2ns((u32)~0, &comparator);
135         comparator.min_delta_ns = clockevent_delta2ns(50, &comparator) + 1;
136         comparator.cpumask = cpumask_of(0);
137
138         sysreg_write(COMPARE, 0);
139         timer_irqaction.dev_id = &comparator;
140
141         ret = setup_irq(0, &timer_irqaction);
142         if (ret)
143                 pr_debug("timer: could not request IRQ 0: %d\n", ret);
144         else {
145                 clockevents_register_device(&comparator);
146
147                 pr_info("%s: irq 0, %lu.%03lu MHz\n", comparator.name,
148                                 ((counter_hz + 500) / 1000) / 1000,
149                                 ((counter_hz + 500) / 1000) % 1000);
150         }
151 }