arch/s390/kernel/idle.c

   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 <trace/events/power.h>
  18 #include <asm/nmi.h>
  19 #include <asm/smp.h>
  20 #include "entry.h"
  21
  22 static DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
  23
  24 void arch_cpu_idle(void)
  25 {
  26         struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
  27         unsigned long long idle_time;
  28         unsigned long psw_mask, flags;
  29
  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         raw_local_irq_save(flags);
  37         /* Call the assembler magic in entry.S */
  38         psw_idle(idle, psw_mask);
  39         raw_local_irq_restore(flags);
  40
  41         /* Account time spent with enabled wait psw loaded as idle time. */
  42         raw_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         raw_write_seqcount_end(&idle->seqcount);
  49         raw_local_irq_enable();
  50 }
  51 NOKPROBE_SYMBOL(arch_cpu_idle);
  52
  53 static ssize_t show_idle_count(struct device *dev,
  54                                 struct device_attribute *attr, char *buf)
  55 {
  56         struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
  57         unsigned long long idle_count;
  58         unsigned int seq;
  59
  60         do {
  61                 seq = read_seqcount_begin(&idle->seqcount);
  62                 idle_count = READ_ONCE(idle->idle_count);
  63                 if (READ_ONCE(idle->clock_idle_enter))
  64                         idle_count++;
  65         } while (read_seqcount_retry(&idle->seqcount, seq));
  66         return sprintf(buf, "%llu\n", idle_count);
  67 }
  68 DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
  69
  70 static ssize_t show_idle_time(struct device *dev,
  71                                 struct device_attribute *attr, char *buf)
  72 {
  73         unsigned long long now, idle_time, idle_enter, idle_exit, in_idle;
  74         struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
  75         unsigned int seq;
  76
  77         do {
  78                 seq = read_seqcount_begin(&idle->seqcount);
  79                 idle_time = READ_ONCE(idle->idle_time);
  80                 idle_enter = READ_ONCE(idle->clock_idle_enter);
  81                 idle_exit = READ_ONCE(idle->clock_idle_exit);
  82         } while (read_seqcount_retry(&idle->seqcount, seq));
  83         in_idle = 0;
  84         now = get_tod_clock();
  85         if (idle_enter) {
  86                 if (idle_exit) {
  87                         in_idle = idle_exit - idle_enter;
  88                 } else if (now > idle_enter) {
  89                         in_idle = now - idle_enter;
  90                 }
  91         }
  92         idle_time += in_idle;
  93         return sprintf(buf, "%llu\n", idle_time >> 12);
  94 }
  95 DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL);
  96
  97 u64 arch_cpu_idle_time(int cpu)
  98 {
  99         struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
 100         unsigned long long now, idle_enter, idle_exit, in_idle;
 101         unsigned int seq;
 102
 103         do {
 104                 seq = read_seqcount_begin(&idle->seqcount);
 105                 idle_enter = READ_ONCE(idle->clock_idle_enter);
 106                 idle_exit = READ_ONCE(idle->clock_idle_exit);
 107         } while (read_seqcount_retry(&idle->seqcount, seq));
 108         in_idle = 0;
 109         now = get_tod_clock();
 110         if (idle_enter) {
 111                 if (idle_exit) {
 112                         in_idle = idle_exit - idle_enter;
 113                 } else if (now > idle_enter) {
 114                         in_idle = now - idle_enter;
 115                 }
 116         }
 117         return cputime_to_nsecs(in_idle);
 118 }
 119
 120 void arch_cpu_idle_enter(void)
 121 {
 122 }
 123
 124 void arch_cpu_idle_exit(void)
 125 {
 126 }
 127
 128 void arch_cpu_idle_dead(void)
 129 {
 130         cpu_die();
 131 }