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 static bool disable_cpu_idle_poll;
22
read_cycle_count(struct clocksource * cs)23 static cycle_t read_cycle_count(struct clocksource *cs)
24 {
25 return (cycle_t)sysreg_read(COUNT);
26 }
27
28 /*
29 * The architectural cycle count registers are a fine clocksource unless
30 * the system idle loop use sleep states like "idle": the CPU cycles
31 * measured by COUNT (and COMPARE) don't happen during sleep states.
32 * Their duration also changes if cpufreq changes the CPU clock rate.
33 * So we rate the clocksource using COUNT as very low quality.
34 */
35 static struct clocksource counter = {
36 .name = "avr32_counter",
37 .rating = 50,
38 .read = read_cycle_count,
39 .mask = CLOCKSOURCE_MASK(32),
40 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
41 };
42
timer_interrupt(int irq,void * dev_id)43 static irqreturn_t timer_interrupt(int irq, void *dev_id)
44 {
45 struct clock_event_device *evdev = dev_id;
46
47 if (unlikely(!(intc_get_pending(0) & 1)))
48 return IRQ_NONE;
49
50 /*
51 * Disable the interrupt until the clockevent subsystem
52 * reprograms it.
53 */
54 sysreg_write(COMPARE, 0);
55
56 evdev->event_handler(evdev);
57 return IRQ_HANDLED;
58 }
59
60 static struct irqaction timer_irqaction = {
61 .handler = timer_interrupt,
62 /* Oprofile uses the same irq as the timer, so allow it to be shared */
63 .flags = IRQF_TIMER | IRQF_SHARED,
64 .name = "avr32_comparator",
65 };
66
comparator_next_event(unsigned long delta,struct clock_event_device * evdev)67 static int comparator_next_event(unsigned long delta,
68 struct clock_event_device *evdev)
69 {
70 unsigned long flags;
71
72 raw_local_irq_save(flags);
73
74 /* The time to read COUNT then update COMPARE must be less
75 * than the min_delta_ns value for this clockevent source.
76 */
77 sysreg_write(COMPARE, (sysreg_read(COUNT) + delta) ? : 1);
78
79 raw_local_irq_restore(flags);
80
81 return 0;
82 }
83
comparator_shutdown(struct clock_event_device * evdev)84 static int comparator_shutdown(struct clock_event_device *evdev)
85 {
86 pr_debug("%s: %s\n", __func__, evdev->name);
87 sysreg_write(COMPARE, 0);
88
89 if (disable_cpu_idle_poll) {
90 disable_cpu_idle_poll = false;
91 /*
92 * Only disable idle poll if we have forced that
93 * in a previous call.
94 */
95 cpu_idle_poll_ctrl(false);
96 }
97 return 0;
98 }
99
comparator_set_oneshot(struct clock_event_device * evdev)100 static int comparator_set_oneshot(struct clock_event_device *evdev)
101 {
102 pr_debug("%s: %s\n", __func__, evdev->name);
103
104 disable_cpu_idle_poll = true;
105 /*
106 * If we're using the COUNT and COMPARE registers we
107 * need to force idle poll.
108 */
109 cpu_idle_poll_ctrl(true);
110
111 return 0;
112 }
113
114 static struct clock_event_device comparator = {
115 .name = "avr32_comparator",
116 .features = CLOCK_EVT_FEAT_ONESHOT,
117 .shift = 16,
118 .rating = 50,
119 .set_next_event = comparator_next_event,
120 .set_state_shutdown = comparator_shutdown,
121 .set_state_oneshot = comparator_set_oneshot,
122 .tick_resume = comparator_set_oneshot,
123 };
124
read_persistent_clock(struct timespec * ts)125 void read_persistent_clock(struct timespec *ts)
126 {
127 ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0);
128 ts->tv_nsec = 0;
129 }
130
time_init(void)131 void __init time_init(void)
132 {
133 unsigned long counter_hz;
134 int ret;
135
136 /* figure rate for counter */
137 counter_hz = clk_get_rate(boot_cpu_data.clk);
138 ret = clocksource_register_hz(&counter, counter_hz);
139 if (ret)
140 pr_debug("timer: could not register clocksource: %d\n", ret);
141
142 /* setup COMPARE clockevent */
143 comparator.mult = div_sc(counter_hz, NSEC_PER_SEC, comparator.shift);
144 comparator.max_delta_ns = clockevent_delta2ns((u32)~0, &comparator);
145 comparator.min_delta_ns = clockevent_delta2ns(50, &comparator) + 1;
146 comparator.cpumask = cpumask_of(0);
147
148 sysreg_write(COMPARE, 0);
149 timer_irqaction.dev_id = &comparator;
150
151 ret = setup_irq(0, &timer_irqaction);
152 if (ret)
153 pr_debug("timer: could not request IRQ 0: %d\n", ret);
154 else {
155 clockevents_register_device(&comparator);
156
157 pr_info("%s: irq 0, %lu.%03lu MHz\n", comparator.name,
158 ((counter_hz + 500) / 1000) / 1000,
159 ((counter_hz + 500) / 1000) % 1000);
160 }
161 }
162