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 void gic_update_frequency(void *data)
77 unsigned long rate = (unsigned long)data;
79 clockevents_update_freq(this_cpu_ptr(&gic_clockevent_device), rate);
82 static int gic_cpu_notifier(struct notifier_block *nb, unsigned long action,
85 switch (action & ~CPU_TASKS_FROZEN) {
87 gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device));
90 gic_clockevent_cpu_exit(this_cpu_ptr(&gic_clockevent_device));
97 static int gic_clk_notifier(struct notifier_block *nb, unsigned long action,
100 struct clk_notifier_data *cnd = data;
102 if (action == POST_RATE_CHANGE)
103 on_each_cpu(gic_update_frequency, (void *)cnd->new_rate, 1);
109 static struct notifier_block gic_cpu_nb = {
110 .notifier_call = gic_cpu_notifier,
113 static struct notifier_block gic_clk_nb = {
114 .notifier_call = gic_clk_notifier,
117 static int gic_clockevent_init(void)
121 if (!cpu_has_counter || !gic_frequency)
124 ret = setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction);
128 ret = register_cpu_notifier(&gic_cpu_nb);
130 pr_warn("GIC: Unable to register CPU notifier\n");
132 gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device));
137 static cycle_t gic_hpt_read(struct clocksource *cs)
139 return gic_read_count();
142 static struct clocksource gic_clocksource = {
144 .read = gic_hpt_read,
145 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
148 static void __init __gic_clocksource_init(void)
152 /* Set clocksource mask. */
153 gic_clocksource.mask = CLOCKSOURCE_MASK(gic_get_count_width());
155 /* Calculate a somewhat reasonable rating value. */
156 gic_clocksource.rating = 200 + gic_frequency / 10000000;
158 ret = clocksource_register_hz(&gic_clocksource, gic_frequency);
160 pr_warn("GIC: Unable to register clocksource\n");
163 void __init gic_clocksource_init(unsigned int frequency)
165 gic_frequency = frequency;
166 gic_timer_irq = MIPS_GIC_IRQ_BASE +
167 GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_COMPARE);
169 __gic_clocksource_init();
170 gic_clockevent_init();
172 /* And finally start the counter */
176 static void __init gic_clocksource_of_init(struct device_node *node)
181 if (WARN_ON(!gic_present || !node->parent ||
182 !of_device_is_compatible(node->parent, "mti,gic")))
185 clk = of_clk_get(node, 0);
187 if (clk_prepare_enable(clk) < 0) {
188 pr_err("GIC failed to enable clock\n");
193 gic_frequency = clk_get_rate(clk);
194 } else if (of_property_read_u32(node, "clock-frequency",
196 pr_err("GIC frequency not specified.\n");
199 gic_timer_irq = irq_of_parse_and_map(node, 0);
200 if (!gic_timer_irq) {
201 pr_err("GIC timer IRQ not specified.\n");
205 __gic_clocksource_init();
207 ret = gic_clockevent_init();
208 if (!ret && !IS_ERR(clk)) {
209 if (clk_notifier_register(clk, &gic_clk_nb) < 0)
210 pr_warn("GIC: Unable to register clock notifier\n");
213 /* And finally start the counter */
216 CLOCKSOURCE_OF_DECLARE(mips_gic_timer, "mti,gic-timer",
217 gic_clocksource_of_init);