1/*
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
4 * for more details.
5 *
6 * Copyright (C) 2012 MIPS Technologies, Inc.  All rights reserved.
7 */
8#include <linux/clk.h>
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>
19
20static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);
21static int gic_timer_irq;
22static unsigned int gic_frequency;
23
24static int gic_next_event(unsigned long delta, struct clock_event_device *evt)
25{
26	u64 cnt;
27	int res;
28
29	cnt = gic_read_count();
30	cnt += (u64)delta;
31	gic_write_cpu_compare(cnt, cpumask_first(evt->cpumask));
32	res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0;
33	return res;
34}
35
36static void gic_set_clock_mode(enum clock_event_mode mode,
37				struct clock_event_device *evt)
38{
39	/* Nothing to do ...  */
40}
41
42static irqreturn_t gic_compare_interrupt(int irq, void *dev_id)
43{
44	struct clock_event_device *cd = dev_id;
45
46	gic_write_compare(gic_read_compare());
47	cd->event_handler(cd);
48	return IRQ_HANDLED;
49}
50
51struct irqaction gic_compare_irqaction = {
52	.handler = gic_compare_interrupt,
53	.percpu_dev_id = &gic_clockevent_device,
54	.flags = IRQF_PERCPU | IRQF_TIMER,
55	.name = "timer",
56};
57
58static void gic_clockevent_cpu_init(struct clock_event_device *cd)
59{
60	unsigned int cpu = smp_processor_id();
61
62	cd->name		= "MIPS GIC";
63	cd->features		= CLOCK_EVT_FEAT_ONESHOT |
64				  CLOCK_EVT_FEAT_C3STOP;
65
66	cd->rating		= 350;
67	cd->irq			= gic_timer_irq;
68	cd->cpumask		= cpumask_of(cpu);
69	cd->set_next_event	= gic_next_event;
70	cd->set_mode		= gic_set_clock_mode;
71
72	clockevents_config_and_register(cd, gic_frequency, 0x300, 0x7fffffff);
73
74	enable_percpu_irq(gic_timer_irq, IRQ_TYPE_NONE);
75}
76
77static void gic_clockevent_cpu_exit(struct clock_event_device *cd)
78{
79	disable_percpu_irq(gic_timer_irq);
80}
81
82static int gic_cpu_notifier(struct notifier_block *nb, unsigned long action,
83				void *data)
84{
85	switch (action & ~CPU_TASKS_FROZEN) {
86	case CPU_STARTING:
87		gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device));
88		break;
89	case CPU_DYING:
90		gic_clockevent_cpu_exit(this_cpu_ptr(&gic_clockevent_device));
91		break;
92	}
93
94	return NOTIFY_OK;
95}
96
97static struct notifier_block gic_cpu_nb = {
98	.notifier_call = gic_cpu_notifier,
99};
100
101static int gic_clockevent_init(void)
102{
103	if (!cpu_has_counter || !gic_frequency)
104		return -ENXIO;
105
106	setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction);
107
108	register_cpu_notifier(&gic_cpu_nb);
109
110	gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device));
111
112	return 0;
113}
114
115static cycle_t gic_hpt_read(struct clocksource *cs)
116{
117	return gic_read_count();
118}
119
120static struct clocksource gic_clocksource = {
121	.name	= "GIC",
122	.read	= gic_hpt_read,
123	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
124};
125
126static void __init __gic_clocksource_init(void)
127{
128	/* Set clocksource mask. */
129	gic_clocksource.mask = CLOCKSOURCE_MASK(gic_get_count_width());
130
131	/* Calculate a somewhat reasonable rating value. */
132	gic_clocksource.rating = 200 + gic_frequency / 10000000;
133
134	clocksource_register_hz(&gic_clocksource, gic_frequency);
135
136	gic_clockevent_init();
137
138	/* And finally start the counter */
139	gic_start_count();
140}
141
142void __init gic_clocksource_init(unsigned int frequency)
143{
144	gic_frequency = frequency;
145	gic_timer_irq = MIPS_GIC_IRQ_BASE +
146		GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_COMPARE);
147
148	__gic_clocksource_init();
149}
150
151static void __init gic_clocksource_of_init(struct device_node *node)
152{
153	struct clk *clk;
154
155	if (WARN_ON(!gic_present || !node->parent ||
156		    !of_device_is_compatible(node->parent, "mti,gic")))
157		return;
158
159	clk = of_clk_get(node, 0);
160	if (!IS_ERR(clk)) {
161		gic_frequency = clk_get_rate(clk);
162		clk_put(clk);
163	} else if (of_property_read_u32(node, "clock-frequency",
164					&gic_frequency)) {
165		pr_err("GIC frequency not specified.\n");
166		return;
167	}
168	gic_timer_irq = irq_of_parse_and_map(node, 0);
169	if (!gic_timer_irq) {
170		pr_err("GIC timer IRQ not specified.\n");
171		return;
172	}
173
174	__gic_clocksource_init();
175}
176CLOCKSOURCE_OF_DECLARE(mips_gic_timer, "mti,gic-timer",
177		       gic_clocksource_of_init);
178