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/cpu_mf.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 account_idle_time_irq(void)
  25 {
  26         struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
  27         u64 cycles_new[8];
  28         int i;
  29
  30         clear_cpu_flag(CIF_ENABLED_WAIT);
  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->clock_idle_exit = S390_lowcore.int_clock;
  38         idle->timer_idle_exit = S390_lowcore.sys_enter_timer;
  39
  40         S390_lowcore.steal_timer += idle->clock_idle_enter - S390_lowcore.last_update_clock;
  41         S390_lowcore.last_update_clock = idle->clock_idle_exit;
  42
  43         S390_lowcore.system_timer += S390_lowcore.last_update_timer - idle->timer_idle_enter;
  44         S390_lowcore.last_update_timer = idle->timer_idle_exit;
  45 }
  46
  47 void arch_cpu_idle(void)
  48 {
  49         struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
  50         unsigned long long idle_time;
  51         unsigned long psw_mask;
  52
  53         /* Wait for external, I/O or machine check interrupt. */
  54         psw_mask = PSW_KERNEL_BITS | PSW_MASK_WAIT | PSW_MASK_DAT |
  55                 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
  56         clear_cpu_flag(CIF_NOHZ_DELAY);
  57
  58         /* psw_idle() returns with interrupts disabled. */
  59         psw_idle(idle, psw_mask);
  60
  61         /* Account time spent with enabled wait psw loaded as idle time. */
  62         raw_write_seqcount_begin(&idle->seqcount);
  63         idle_time = idle->clock_idle_exit - idle->clock_idle_enter;
  64         idle->clock_idle_enter = idle->clock_idle_exit = 0ULL;
  65         idle->idle_time += idle_time;
  66         idle->idle_count++;
  67         account_idle_time(cputime_to_nsecs(idle_time));
  68         raw_write_seqcount_end(&idle->seqcount);
  69         raw_local_irq_enable();
  70 }
  71
  72 static ssize_t show_idle_count(struct device *dev,
  73                                 struct device_attribute *attr, char *buf)
  74 {
  75         struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
  76         unsigned long long idle_count;
  77         unsigned int seq;
  78
  79         do {
  80                 seq = read_seqcount_begin(&idle->seqcount);
  81                 idle_count = READ_ONCE(idle->idle_count);
  82                 if (READ_ONCE(idle->clock_idle_enter))
  83                         idle_count++;
  84         } while (read_seqcount_retry(&idle->seqcount, seq));
  85         return sprintf(buf, "%llu\n", idle_count);
  86 }
  87 DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
  88
  89 static ssize_t show_idle_time(struct device *dev,
  90                                 struct device_attribute *attr, char *buf)
  91 {
  92         unsigned long long now, idle_time, idle_enter, idle_exit, in_idle;
  93         struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
  94         unsigned int seq;
  95
  96         do {
  97                 seq = read_seqcount_begin(&idle->seqcount);
  98                 idle_time = READ_ONCE(idle->idle_time);
  99                 idle_enter = READ_ONCE(idle->clock_idle_enter);
 100                 idle_exit = READ_ONCE(idle->clock_idle_exit);
 101         } while (read_seqcount_retry(&idle->seqcount, seq));
 102         in_idle = 0;
 103         now = get_tod_clock();
 104         if (idle_enter) {
 105                 if (idle_exit) {
 106                         in_idle = idle_exit - idle_enter;
 107                 } else if (now > idle_enter) {
 108                         in_idle = now - idle_enter;
 109                 }
 110         }
 111         idle_time += in_idle;
 112         return sprintf(buf, "%llu\n", idle_time >> 12);
 113 }
 114 DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL);
 115
 116 u64 arch_cpu_idle_time(int cpu)
 117 {
 118         struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
 119         unsigned long long now, idle_enter, idle_exit, in_idle;
 120         unsigned int seq;
 121
 122         do {
 123                 seq = read_seqcount_begin(&idle->seqcount);
 124                 idle_enter = READ_ONCE(idle->clock_idle_enter);
 125                 idle_exit = READ_ONCE(idle->clock_idle_exit);
 126         } while (read_seqcount_retry(&idle->seqcount, seq));
 127         in_idle = 0;
 128         now = get_tod_clock();
 129         if (idle_enter) {
 130                 if (idle_exit) {
 131                         in_idle = idle_exit - idle_enter;
 132                 } else if (now > idle_enter) {
 133                         in_idle = now - idle_enter;
 134                 }
 135         }
 136         return cputime_to_nsecs(in_idle);
 137 }
 138
 139 void arch_cpu_idle_enter(void)
 140 {
 141 }
 142
 143 void arch_cpu_idle_exit(void)
 144 {
 145 }
 146
 147 void arch_cpu_idle_dead(void)
 148 {
 149         cpu_die();
 150 }