2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
6 * Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
8 #include <linux/clockchips.h>
9 #include <linux/init.h>
10 #include <linux/interrupt.h>
11 #include <linux/irqchip/mips-gic.h>
12 #include <linux/percpu.h>
13 #include <linux/smp.h>
14 #include <linux/time.h>
18 static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);
19 static int gic_timer_irq_installed;
20 static unsigned int gic_frequency;
22 static int gic_next_event(unsigned long delta, struct clock_event_device *evt)
27 cnt = gic_read_count();
29 gic_write_cpu_compare(cnt, cpumask_first(evt->cpumask));
30 res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0;
34 static void gic_set_clock_mode(enum clock_event_mode mode,
35 struct clock_event_device *evt)
37 /* Nothing to do ... */
40 static irqreturn_t gic_compare_interrupt(int irq, void *dev_id)
42 struct clock_event_device *cd;
43 int cpu = smp_processor_id();
45 gic_write_compare(gic_read_compare());
46 cd = &per_cpu(gic_clockevent_device, cpu);
47 cd->event_handler(cd);
51 struct irqaction gic_compare_irqaction = {
52 .handler = gic_compare_interrupt,
53 .flags = IRQF_PERCPU | IRQF_TIMER,
57 static void gic_event_handler(struct clock_event_device *dev)
61 int gic_clockevent_init(void)
63 unsigned int cpu = smp_processor_id();
64 struct clock_event_device *cd;
67 if (!cpu_has_counter || !gic_frequency)
70 irq = MIPS_GIC_IRQ_BASE + GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_COMPARE);
72 cd = &per_cpu(gic_clockevent_device, cpu);
74 cd->name = "MIPS GIC";
75 cd->features = CLOCK_EVT_FEAT_ONESHOT |
76 CLOCK_EVT_FEAT_C3STOP;
78 clockevent_set_clock(cd, gic_frequency);
80 /* Calculate the min / max delta */
81 cd->max_delta_ns = clockevent_delta2ns(0x7fffffff, cd);
82 cd->min_delta_ns = clockevent_delta2ns(0x300, cd);
86 cd->cpumask = cpumask_of(cpu);
87 cd->set_next_event = gic_next_event;
88 cd->set_mode = gic_set_clock_mode;
89 cd->event_handler = gic_event_handler;
91 clockevents_register_device(cd);
93 if (!gic_timer_irq_installed) {
94 setup_percpu_irq(irq, &gic_compare_irqaction);
95 gic_timer_irq_installed = 1;
98 enable_percpu_irq(irq, IRQ_TYPE_NONE);
103 static cycle_t gic_hpt_read(struct clocksource *cs)
105 return gic_read_count();
108 static struct clocksource gic_clocksource = {
110 .read = gic_hpt_read,
111 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
114 void __init gic_clocksource_init(unsigned int frequency)
116 gic_frequency = frequency;
118 /* Set clocksource mask. */
119 gic_clocksource.mask = CLOCKSOURCE_MASK(gic_get_count_width());
121 /* Calculate a somewhat reasonable rating value. */
122 gic_clocksource.rating = 200 + frequency / 10000000;
124 clocksource_register_hz(&gic_clocksource, frequency);