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/notifier.h>
  13 #include <linux/init.h>
  14 #include <linux/cpu.h>
  15 #include <linux/sched/cputime.h>
  16 #include <trace/events/power.h>
  17 #include <asm/nmi.h>
  18 #include <asm/smp.h>
  19 #include "entry.h"
  20
  21 static DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
  22
  23 void arch_cpu_idle(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         /* Wait for external, I/O or machine check interrupt. */
  30         psw_mask = PSW_KERNEL_BITS | PSW_MASK_WAIT | PSW_MASK_DAT |
  31                 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
  32         clear_cpu_flag(CIF_NOHZ_DELAY);
  33
  34         /* psw_idle() returns with interrupts disabled. */
  35         psw_idle(idle, psw_mask);
  36
  37         /* Account time spent with enabled wait psw loaded as idle time. */
  38         raw_write_seqcount_begin(&idle->seqcount);
  39         idle_time = idle->clock_idle_exit - idle->clock_idle_enter;
  40         idle->clock_idle_enter = idle->clock_idle_exit = 0ULL;
  41         idle->idle_time += idle_time;
  42         idle->idle_count++;
  43         account_idle_time(cputime_to_nsecs(idle_time));
  44         raw_write_seqcount_end(&idle->seqcount);
  45         raw_local_irq_enable();
  46 }
  47
  48 static ssize_t show_idle_count(struct device *dev,
  49                                 struct device_attribute *attr, char *buf)
  50 {
  51         struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
  52         unsigned long long idle_count;
  53         unsigned int seq;
  54
  55         do {
  56                 seq = read_seqcount_begin(&idle->seqcount);
  57                 idle_count = READ_ONCE(idle->idle_count);
  58                 if (READ_ONCE(idle->clock_idle_enter))
  59                         idle_count++;
  60         } while (read_seqcount_retry(&idle->seqcount, seq));
  61         return sprintf(buf, "%llu\n", idle_count);
  62 }
  63 DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
  64
  65 static ssize_t show_idle_time(struct device *dev,
  66                                 struct device_attribute *attr, char *buf)
  67 {
  68         unsigned long long now, idle_time, idle_enter, idle_exit, in_idle;
  69         struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
  70         unsigned int seq;
  71
  72         do {
  73                 seq = read_seqcount_begin(&idle->seqcount);
  74                 idle_time = READ_ONCE(idle->idle_time);
  75                 idle_enter = READ_ONCE(idle->clock_idle_enter);
  76                 idle_exit = READ_ONCE(idle->clock_idle_exit);
  77         } while (read_seqcount_retry(&idle->seqcount, seq));
  78         in_idle = 0;
  79         now = get_tod_clock();
  80         if (idle_enter) {
  81                 if (idle_exit) {
  82                         in_idle = idle_exit - idle_enter;
  83                 } else if (now > idle_enter) {
  84                         in_idle = now - idle_enter;
  85                 }
  86         }
  87         idle_time += in_idle;
  88         return sprintf(buf, "%llu\n", idle_time >> 12);
  89 }
  90 DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL);
  91
  92 u64 arch_cpu_idle_time(int cpu)
  93 {
  94         struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
  95         unsigned long long now, idle_enter, idle_exit, in_idle;
  96         unsigned int seq;
  97
  98         do {
  99                 seq = read_seqcount_begin(&idle->seqcount);
 100                 idle_enter = READ_ONCE(idle->clock_idle_enter);
 101                 idle_exit = READ_ONCE(idle->clock_idle_exit);
 102         } while (read_seqcount_retry(&idle->seqcount, seq));
 103         in_idle = 0;
 104         now = get_tod_clock();
 105         if (idle_enter) {
 106                 if (idle_exit) {
 107                         in_idle = idle_exit - idle_enter;
 108                 } else if (now > idle_enter) {
 109                         in_idle = now - idle_enter;
 110                 }
 111         }
 112         return cputime_to_nsecs(in_idle);
 113 }
 114
 115 void arch_cpu_idle_enter(void)
 116 {
 117 }
 118
 119 void arch_cpu_idle_exit(void)
 120 {
 121 }
 122
 123 void arch_cpu_idle_dead(void)
 124 {
 125         cpu_die();
 126 }