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/kprobes.h>
 13#include <linux/notifier.h>
 14#include <linux/init.h>
 15#include <linux/cpu.h>
 16#include <linux/sched/cputime.h>
 17#include <asm/nmi.h>
 18#include <asm/smp.h>
 19#include "entry.h"
 20
 21static DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
 22
 23void enabled_wait(void)
 24{
 25	struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
 26	unsigned long long idle_time;
 27	unsigned long psw_mask;
 28
 29	trace_hardirqs_on();
 30
 31	/* Wait for external, I/O or machine check interrupt. */
 32	psw_mask = PSW_KERNEL_BITS | PSW_MASK_WAIT | PSW_MASK_DAT |
 33		PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 34	clear_cpu_flag(CIF_NOHZ_DELAY);
 35
 36	/* Call the assembler magic in entry.S */
 37	psw_idle(idle, psw_mask);
 38
 39	trace_hardirqs_off();
 40
 41	/* Account time spent with enabled wait psw loaded as idle time. */
 42	write_seqcount_begin(&idle->seqcount);
 43	idle_time = idle->clock_idle_exit - idle->clock_idle_enter;
 44	idle->clock_idle_enter = idle->clock_idle_exit = 0ULL;
 45	idle->idle_time += idle_time;
 46	idle->idle_count++;
 47	account_idle_time(cputime_to_nsecs(idle_time));
 48	write_seqcount_end(&idle->seqcount);
 49}
 50NOKPROBE_SYMBOL(enabled_wait);
 51
 52static ssize_t show_idle_count(struct device *dev,
 53				struct device_attribute *attr, char *buf)
 54{
 55	struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
 56	unsigned long long idle_count;
 57	unsigned int seq;
 58
 59	do {
 60		seq = read_seqcount_begin(&idle->seqcount);
 61		idle_count = READ_ONCE(idle->idle_count);
 62		if (READ_ONCE(idle->clock_idle_enter))
 63			idle_count++;
 64	} while (read_seqcount_retry(&idle->seqcount, seq));
 65	return sprintf(buf, "%llu\n", idle_count);
 66}
 67DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
 68
 69static ssize_t show_idle_time(struct device *dev,
 70				struct device_attribute *attr, char *buf)
 71{
 72	unsigned long long now, idle_time, idle_enter, idle_exit, in_idle;
 73	struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
 74	unsigned int seq;
 75
 76	do {
 77		seq = read_seqcount_begin(&idle->seqcount);
 78		idle_time = READ_ONCE(idle->idle_time);
 79		idle_enter = READ_ONCE(idle->clock_idle_enter);
 80		idle_exit = READ_ONCE(idle->clock_idle_exit);
 81	} while (read_seqcount_retry(&idle->seqcount, seq));
 82	in_idle = 0;
 83	now = get_tod_clock();
 84	if (idle_enter) {
 85		if (idle_exit) {
 86			in_idle = idle_exit - idle_enter;
 87		} else if (now > idle_enter) {
 88			in_idle = now - idle_enter;
 89		}
 90	}
 91	idle_time += in_idle;
 92	return sprintf(buf, "%llu\n", idle_time >> 12);
 93}
 94DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL);
 95
 96u64 arch_cpu_idle_time(int cpu)
 97{
 98	struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
 99	unsigned long long now, idle_enter, idle_exit, in_idle;
100	unsigned int seq;
101
102	do {
103		seq = read_seqcount_begin(&idle->seqcount);
104		idle_enter = READ_ONCE(idle->clock_idle_enter);
105		idle_exit = READ_ONCE(idle->clock_idle_exit);
106	} while (read_seqcount_retry(&idle->seqcount, seq));
107	in_idle = 0;
108	now = get_tod_clock();
109	if (idle_enter) {
110		if (idle_exit) {
111			in_idle = idle_exit - idle_enter;
112		} else if (now > idle_enter) {
113			in_idle = now - idle_enter;
114		}
115	}
116	return cputime_to_nsecs(in_idle);
117}
118
119void arch_cpu_idle_enter(void)
120{
121	local_mcck_disable();
122}
123
124void arch_cpu_idle(void)
125{
126	if (!test_cpu_flag(CIF_MCCK_PENDING))
127		/* Halt the cpu and keep track of cpu time accounting. */
128		enabled_wait();
129	local_irq_enable();
130}
131
132void arch_cpu_idle_exit(void)
133{
134	local_mcck_enable();
135	if (test_cpu_flag(CIF_MCCK_PENDING))
136		s390_handle_mcck();
137}
138
139void arch_cpu_idle_dead(void)
140{
141	cpu_die();
142}