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1 /*
2 * arch/xtensa/kernel/time.c
3 *
4 * Timer and clock support.
5 *
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License. See the file "COPYING" in the main directory of this archive
8 * for more details.
9 *
10 * Copyright (C) 2005 Tensilica Inc.
11 *
12 * Chris Zankel <chris@zankel.net>
13 */
14
15 #include <linux/clk.h>
16 #include <linux/clk-provider.h>
17 #include <linux/errno.h>
18 #include <linux/sched.h>
19 #include <linux/time.h>
20 #include <linux/clocksource.h>
21 #include <linux/clockchips.h>
22 #include <linux/interrupt.h>
23 #include <linux/module.h>
24 #include <linux/init.h>
25 #include <linux/irq.h>
26 #include <linux/profile.h>
27 #include <linux/delay.h>
28 #include <linux/irqdomain.h>
29 #include <linux/sched_clock.h>
30
31 #include <asm/timex.h>
32 #include <asm/platform.h>
33
34 unsigned long ccount_freq; /* ccount Hz */
35 EXPORT_SYMBOL(ccount_freq);
36
37 static u64 ccount_read(struct clocksource *cs)
38 {
39 return (u64)get_ccount();
40 }
41
42 static u64 notrace ccount_sched_clock_read(void)
43 {
44 return get_ccount();
45 }
46
47 static struct clocksource ccount_clocksource = {
48 .name = "ccount",
49 .rating = 200,
50 .read = ccount_read,
51 .mask = CLOCKSOURCE_MASK(32),
52 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
53 };
54
55 static int ccount_timer_set_next_event(unsigned long delta,
56 struct clock_event_device *dev);
57 struct ccount_timer {
58 struct clock_event_device evt;
59 int irq_enabled;
60 char name[24];
61 };
62 static DEFINE_PER_CPU(struct ccount_timer, ccount_timer);
63
64 static int ccount_timer_set_next_event(unsigned long delta,
65 struct clock_event_device *dev)
66 {
67 unsigned long flags, next;
68 int ret = 0;
69
70 local_irq_save(flags);
71 next = get_ccount() + delta;
72 set_linux_timer(next);
73 if (next - get_ccount() > delta)
74 ret = -ETIME;
75 local_irq_restore(flags);
76
77 return ret;
78 }
79
80 /*
81 * There is no way to disable the timer interrupt at the device level,
82 * only at the intenable register itself. Since enable_irq/disable_irq
83 * calls are nested, we need to make sure that these calls are
84 * balanced.
85 */
86 static int ccount_timer_shutdown(struct clock_event_device *evt)
87 {
88 struct ccount_timer *timer =
89 container_of(evt, struct ccount_timer, evt);
90
91 if (timer->irq_enabled) {
92 disable_irq(evt->irq);
93 timer->irq_enabled = 0;
94 }
95 return 0;
96 }
97
98 static int ccount_timer_set_oneshot(struct clock_event_device *evt)
99 {
100 struct ccount_timer *timer =
101 container_of(evt, struct ccount_timer, evt);
102
103 if (!timer->irq_enabled) {
104 enable_irq(evt->irq);
105 timer->irq_enabled = 1;
106 }
107 return 0;
108 }
109
110 static irqreturn_t timer_interrupt(int irq, void *dev_id);
111 static struct irqaction timer_irqaction = {
112 .handler = timer_interrupt,
113 .flags = IRQF_TIMER,
114 .name = "timer",
115 };
116
117 void local_timer_setup(unsigned cpu)
118 {
119 struct ccount_timer *timer = &per_cpu(ccount_timer, cpu);
120 struct clock_event_device *clockevent = &timer->evt;
121
122 timer->irq_enabled = 1;
123 clockevent->name = timer->name;
124 snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu);
125 clockevent->features = CLOCK_EVT_FEAT_ONESHOT;
126 clockevent->rating = 300;
127 clockevent->set_next_event = ccount_timer_set_next_event;
128 clockevent->set_state_shutdown = ccount_timer_shutdown;
129 clockevent->set_state_oneshot = ccount_timer_set_oneshot;
130 clockevent->tick_resume = ccount_timer_set_oneshot;
131 clockevent->cpumask = cpumask_of(cpu);
132 clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
133 if (WARN(!clockevent->irq, "error: can't map timer irq"))
134 return;
135 clockevents_config_and_register(clockevent, ccount_freq,
136 0xf, 0xffffffff);
137 }
138
139 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
140 #ifdef CONFIG_OF
141 static void __init calibrate_ccount(void)
142 {
143 struct device_node *cpu;
144 struct clk *clk;
145
146 cpu = of_find_compatible_node(NULL, NULL, "cdns,xtensa-cpu");
147 if (cpu) {
148 clk = of_clk_get(cpu, 0);
149 if (!IS_ERR(clk)) {
150 ccount_freq = clk_get_rate(clk);
151 return;
152 } else {
153 pr_warn("%s: CPU input clock not found\n",
154 __func__);
155 }
156 } else {
157 pr_warn("%s: CPU node not found in the device tree\n",
158 __func__);
159 }
160
161 platform_calibrate_ccount();
162 }
163 #else
164 static inline void calibrate_ccount(void)
165 {
166 platform_calibrate_ccount();
167 }
168 #endif
169 #endif
170
171 void __init time_init(void)
172 {
173 of_clk_init(NULL);
174 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
175 pr_info("Calibrating CPU frequency ");
176 calibrate_ccount();
177 pr_cont("%d.%02d MHz\n",
178 (int)ccount_freq / 1000000,
179 (int)(ccount_freq / 10000) % 100);
180 #else
181 ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL;
182 #endif
183 WARN(!ccount_freq,
184 "%s: CPU clock frequency is not set up correctly\n",
185 __func__);
186 clocksource_register_hz(&ccount_clocksource, ccount_freq);
187 local_timer_setup(0);
188 setup_irq(this_cpu_ptr(&ccount_timer)->evt.irq, &timer_irqaction);
189 sched_clock_register(ccount_sched_clock_read, 32, ccount_freq);
190 timer_probe();
191 }
192
193 /*
194 * The timer interrupt is called HZ times per second.
195 */
196
197 irqreturn_t timer_interrupt(int irq, void *dev_id)
198 {
199 struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt;
200
201 set_linux_timer(get_linux_timer());
202 evt->event_handler(evt);
203
204 /* Allow platform to do something useful (Wdog). */
205 platform_heartbeat();
206
207 return IRQ_HANDLED;
208 }
209
210 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY
211 void calibrate_delay(void)
212 {
213 loops_per_jiffy = ccount_freq / HZ;
214 pr_info("Calibrating delay loop (skipped)... %lu.%02lu BogoMIPS preset\n",
215 loops_per_jiffy / (1000000 / HZ),
216 (loops_per_jiffy / (10000 / HZ)) % 100);
217 }
218 #endif