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 #include <linux/cpu.h>
16
17 #include <asm/sysreg.h>
18
19 #include <mach/pm.h>
20
21
read_cycle_count(struct clocksource * cs)22 static cycle_t read_cycle_count(struct clocksource *cs)
23 {
24 return (cycle_t)sysreg_read(COUNT);
25 }
26
27 /*
28 * The architectural cycle count registers are a fine clocksource unless
29 * the system idle loop use sleep states like "idle": the CPU cycles
30 * measured by COUNT (and COMPARE) don't happen during sleep states.
31 * Their duration also changes if cpufreq changes the CPU clock rate.
32 * So we rate the clocksource using COUNT as very low quality.
33 */
34 static struct clocksource counter = {
35 .name = "avr32_counter",
36 .rating = 50,
37 .read = read_cycle_count,
38 .mask = CLOCKSOURCE_MASK(32),
39 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
40 };
41
timer_interrupt(int irq,void * dev_id)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_SHARED,
63 .name = "avr32_comparator",
64 };
65
comparator_next_event(unsigned long delta,struct clock_event_device * evdev)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
comparator_mode(enum clock_event_mode mode,struct clock_event_device * evdev)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 /*
92 * If we're using the COUNT and COMPARE registers we
93 * need to force idle poll.
94 */
95 cpu_idle_poll_ctrl(true);
96 break;
97 case CLOCK_EVT_MODE_UNUSED:
98 case CLOCK_EVT_MODE_SHUTDOWN:
99 sysreg_write(COMPARE, 0);
100 pr_debug("%s: stop\n", evdev->name);
101 if (evdev->mode == CLOCK_EVT_MODE_ONESHOT ||
102 evdev->mode == CLOCK_EVT_MODE_RESUME) {
103 /*
104 * Only disable idle poll if we have forced that
105 * in a previous call.
106 */
107 cpu_idle_poll_ctrl(false);
108 }
109 break;
110 default:
111 BUG();
112 }
113 }
114
115 static struct clock_event_device comparator = {
116 .name = "avr32_comparator",
117 .features = CLOCK_EVT_FEAT_ONESHOT,
118 .shift = 16,
119 .rating = 50,
120 .set_next_event = comparator_next_event,
121 .set_mode = comparator_mode,
122 };
123
read_persistent_clock(struct timespec * ts)124 void read_persistent_clock(struct timespec *ts)
125 {
126 ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0);
127 ts->tv_nsec = 0;
128 }
129
time_init(void)130 void __init time_init(void)
131 {
132 unsigned long counter_hz;
133 int ret;
134
135 /* figure rate for counter */
136 counter_hz = clk_get_rate(boot_cpu_data.clk);
137 ret = clocksource_register_hz(&counter, counter_hz);
138 if (ret)
139 pr_debug("timer: could not register clocksource: %d\n", ret);
140
141 /* setup COMPARE clockevent */
142 comparator.mult = div_sc(counter_hz, NSEC_PER_SEC, comparator.shift);
143 comparator.max_delta_ns = clockevent_delta2ns((u32)~0, &comparator);
144 comparator.min_delta_ns = clockevent_delta2ns(50, &comparator) + 1;
145 comparator.cpumask = cpumask_of(0);
146
147 sysreg_write(COMPARE, 0);
148 timer_irqaction.dev_id = &comparator;
149
150 ret = setup_irq(0, &timer_irqaction);
151 if (ret)
152 pr_debug("timer: could not request IRQ 0: %d\n", ret);
153 else {
154 clockevents_register_device(&comparator);
155
156 pr_info("%s: irq 0, %lu.%03lu MHz\n", comparator.name,
157 ((counter_hz + 500) / 1000) / 1000,
158 ((counter_hz + 500) / 1000) % 1000);
159 }
160 }
161