1/*
  2 * Idle functions for s390.
  3 *
  4 * Copyright IBM Corp. 2014
  5 *
  6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
  7 */
  8
  9#include <linux/kernel.h>
 10#include <linux/kernel_stat.h>
 11#include <linux/kprobes.h>
 12#include <linux/notifier.h>
 13#include <linux/init.h>
 14#include <linux/cpu.h>
 15#include <asm/cputime.h>
 16#include <asm/nmi.h>
 17#include <asm/smp.h>
 18#include "entry.h"
 19
 20static DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
 21
 22void enabled_wait(void)
 23{
 24	struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
 25	unsigned long long idle_time;
 26	unsigned long psw_mask;
 27
 28	trace_hardirqs_on();
 29
 30	/* Wait for external, I/O or machine check interrupt. */
 31	psw_mask = PSW_KERNEL_BITS | PSW_MASK_WAIT | PSW_MASK_DAT |
 32		PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 33	clear_cpu_flag(CIF_NOHZ_DELAY);
 34
 35	/* Call the assembler magic in entry.S */
 36	psw_idle(idle, psw_mask);
 37
 38	trace_hardirqs_off();
 39
 40	/* Account time spent with enabled wait psw loaded as idle time. */
 41	write_seqcount_begin(&idle->seqcount);
 42	idle_time = idle->clock_idle_exit - idle->clock_idle_enter;
 43	idle->clock_idle_enter = idle->clock_idle_exit = 0ULL;
 44	idle->idle_time += idle_time;
 45	idle->idle_count++;
 46	account_idle_time(idle_time);
 47	write_seqcount_end(&idle->seqcount);
 48}
 49NOKPROBE_SYMBOL(enabled_wait);
 50
 51static ssize_t show_idle_count(struct device *dev,
 52				struct device_attribute *attr, char *buf)
 53{
 54	struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
 55	unsigned long long idle_count;
 56	unsigned int seq;
 57
 58	do {
 59		seq = read_seqcount_begin(&idle->seqcount);
 60		idle_count = ACCESS_ONCE(idle->idle_count);
 61		if (ACCESS_ONCE(idle->clock_idle_enter))
 62			idle_count++;
 63	} while (read_seqcount_retry(&idle->seqcount, seq));
 64	return sprintf(buf, "%llu\n", idle_count);
 65}
 66DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
 67
 68static ssize_t show_idle_time(struct device *dev,
 69				struct device_attribute *attr, char *buf)
 70{
 71	struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
 72	unsigned long long now, idle_time, idle_enter, idle_exit;
 73	unsigned int seq;
 74
 75	do {
 76		now = get_tod_clock();
 77		seq = read_seqcount_begin(&idle->seqcount);
 78		idle_time = ACCESS_ONCE(idle->idle_time);
 79		idle_enter = ACCESS_ONCE(idle->clock_idle_enter);
 80		idle_exit = ACCESS_ONCE(idle->clock_idle_exit);
 81	} while (read_seqcount_retry(&idle->seqcount, seq));
 82	idle_time += idle_enter ? ((idle_exit ? : now) - idle_enter) : 0;
 83	return sprintf(buf, "%llu\n", idle_time >> 12);
 84}
 85DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL);
 86
 87cputime64_t arch_cpu_idle_time(int cpu)
 88{
 89	struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
 90	unsigned long long now, idle_enter, idle_exit;
 91	unsigned int seq;
 92
 93	do {
 94		now = get_tod_clock();
 95		seq = read_seqcount_begin(&idle->seqcount);
 96		idle_enter = ACCESS_ONCE(idle->clock_idle_enter);
 97		idle_exit = ACCESS_ONCE(idle->clock_idle_exit);
 98	} while (read_seqcount_retry(&idle->seqcount, seq));
 99	return idle_enter ? ((idle_exit ?: now) - idle_enter) : 0;
100}
101
102void arch_cpu_idle_enter(void)
103{
104	local_mcck_disable();
105}
106
107void arch_cpu_idle(void)
108{
109	if (!test_cpu_flag(CIF_MCCK_PENDING))
110		/* Halt the cpu and keep track of cpu time accounting. */
111		enabled_wait();
112	local_irq_enable();
113}
114
115void arch_cpu_idle_exit(void)
116{
117	local_mcck_enable();
118	if (test_cpu_flag(CIF_MCCK_PENDING))
119		s390_handle_mcck();
120}
121
122void arch_cpu_idle_dead(void)
123{
124	cpu_die();
125}