1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Idle functions for s390.
4 *
5 * Copyright IBM Corp. 2014
6 *
7 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
8 */
9
10#include <linux/kernel.h>
11#include <linux/kernel_stat.h>
12#include <linux/notifier.h>
13#include <linux/init.h>
14#include <linux/cpu.h>
15#include <trace/events/power.h>
16#include <asm/cpu_mf.h>
17#include <asm/cputime.h>
18#include <asm/nmi.h>
19#include <asm/smp.h>
20#include "entry.h"
21
22static DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
23
24void account_idle_time_irq(void)
25{
26	struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
27	unsigned long idle_time;
28	u64 cycles_new[8];
29	int i;
30
31	if (smp_cpu_mtid) {
32		stcctm(MT_DIAG, smp_cpu_mtid, cycles_new);
33		for (i = 0; i < smp_cpu_mtid; i++)
34			this_cpu_add(mt_cycles[i], cycles_new[i] - idle->mt_cycles_enter[i]);
35	}
36
37	idle_time = S390_lowcore.int_clock - idle->clock_idle_enter;
38
39	S390_lowcore.steal_timer += idle->clock_idle_enter - S390_lowcore.last_update_clock;
40	S390_lowcore.last_update_clock = S390_lowcore.int_clock;
41
42	S390_lowcore.system_timer += S390_lowcore.last_update_timer - idle->timer_idle_enter;
43	S390_lowcore.last_update_timer = S390_lowcore.sys_enter_timer;
44
45	/* Account time spent with enabled wait psw loaded as idle time. */
46	WRITE_ONCE(idle->idle_time, READ_ONCE(idle->idle_time) + idle_time);
47	WRITE_ONCE(idle->idle_count, READ_ONCE(idle->idle_count) + 1);
48	account_idle_time(cputime_to_nsecs(idle_time));
49}
50
51void noinstr arch_cpu_idle(void)
52{
53	struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
54	unsigned long psw_mask;
55
56	/* Wait for external, I/O or machine check interrupt. */
57	psw_mask = PSW_KERNEL_BITS | PSW_MASK_WAIT |
58		   PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
59	clear_cpu_flag(CIF_NOHZ_DELAY);
60
61	/* psw_idle() returns with interrupts disabled. */
62	psw_idle(idle, psw_mask);
63}
64
65static ssize_t show_idle_count(struct device *dev,
66			       struct device_attribute *attr, char *buf)
67{
68	struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
69
70	return sysfs_emit(buf, "%lu\n", READ_ONCE(idle->idle_count));
71}
72DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
73
74static ssize_t show_idle_time(struct device *dev,
75			      struct device_attribute *attr, char *buf)
76{
77	struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
78
79	return sysfs_emit(buf, "%lu\n", READ_ONCE(idle->idle_time) >> 12);
80}
81DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL);
82
83void arch_cpu_idle_enter(void)
84{
85}
86
87void arch_cpu_idle_exit(void)
88{
89}
90
91void __noreturn arch_cpu_idle_dead(void)
92{
93	cpu_die();
94}
95