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.
9 #include <linux/clockchips.h>
10 #include <linux/cpu.h>
11 #include <linux/init.h>
12 #include <linux/interrupt.h>
13 #include <linux/irqchip/mips-gic.h>
14 #include <linux/notifier.h>
15 #include <linux/of_irq.h>
16 #include <linux/percpu.h>
17 #include <linux/smp.h>
18 #include <linux/time.h>
20 static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);
21 static int gic_timer_irq;
22 static unsigned int gic_frequency;
24 static int gic_next_event(unsigned long delta, struct clock_event_device *evt)
29 cnt = gic_read_count();
31 gic_write_cpu_compare(cnt, cpumask_first(evt->cpumask));
32 res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0;
36 static irqreturn_t gic_compare_interrupt(int irq, void *dev_id)
38 struct clock_event_device *cd = dev_id;
40 gic_write_compare(gic_read_compare());
41 cd->event_handler(cd);
45 struct irqaction gic_compare_irqaction = {
46 .handler = gic_compare_interrupt,
47 .percpu_dev_id = &gic_clockevent_device,
48 .flags = IRQF_PERCPU | IRQF_TIMER,
52 static void gic_clockevent_cpu_init(struct clock_event_device *cd)
54 unsigned int cpu = smp_processor_id();
56 cd->name = "MIPS GIC";
57 cd->features = CLOCK_EVT_FEAT_ONESHOT |
58 CLOCK_EVT_FEAT_C3STOP;
61 cd->irq = gic_timer_irq;
62 cd->cpumask = cpumask_of(cpu);
63 cd->set_next_event = gic_next_event;
65 clockevents_config_and_register(cd, gic_frequency, 0x300, 0x7fffffff);
67 enable_percpu_irq(gic_timer_irq, IRQ_TYPE_NONE);
70 static void gic_clockevent_cpu_exit(struct clock_event_device *cd)
72 disable_percpu_irq(gic_timer_irq);
75 static int gic_cpu_notifier(struct notifier_block *nb, unsigned long action,
78 switch (action & ~CPU_TASKS_FROZEN) {
80 gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device));
83 gic_clockevent_cpu_exit(this_cpu_ptr(&gic_clockevent_device));
90 static struct notifier_block gic_cpu_nb = {
91 .notifier_call = gic_cpu_notifier,
94 static int gic_clockevent_init(void)
96 if (!cpu_has_counter || !gic_frequency)
99 setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction);
101 register_cpu_notifier(&gic_cpu_nb);
103 gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device));
108 static cycle_t gic_hpt_read(struct clocksource *cs)
110 return gic_read_count();
113 static struct clocksource gic_clocksource = {
115 .read = gic_hpt_read,
116 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
119 static void __init __gic_clocksource_init(void)
121 /* Set clocksource mask. */
122 gic_clocksource.mask = CLOCKSOURCE_MASK(gic_get_count_width());
124 /* Calculate a somewhat reasonable rating value. */
125 gic_clocksource.rating = 200 + gic_frequency / 10000000;
127 clocksource_register_hz(&gic_clocksource, gic_frequency);
129 gic_clockevent_init();
131 /* And finally start the counter */
135 void __init gic_clocksource_init(unsigned int frequency)
137 gic_frequency = frequency;
138 gic_timer_irq = MIPS_GIC_IRQ_BASE +
139 GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_COMPARE);
141 __gic_clocksource_init();
144 static void __init gic_clocksource_of_init(struct device_node *node)
148 if (WARN_ON(!gic_present || !node->parent ||
149 !of_device_is_compatible(node->parent, "mti,gic")))
152 clk = of_clk_get(node, 0);
154 gic_frequency = clk_get_rate(clk);
156 } else if (of_property_read_u32(node, "clock-frequency",
158 pr_err("GIC frequency not specified.\n");
161 gic_timer_irq = irq_of_parse_and_map(node, 0);
162 if (!gic_timer_irq) {
163 pr_err("GIC timer IRQ not specified.\n");
167 __gic_clocksource_init();
169 CLOCKSOURCE_OF_DECLARE(mips_gic_timer, "mti,gic-timer",
170 gic_clocksource_of_init);