LXR linux/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
  22static DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
  23
  24void 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
  47void arch_cpu_idle(void)
  48{
  49        struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
  50        unsigned 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
  72static 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 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, "%lu\n", idle_count);
  86}
  87DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
  88
  89static ssize_t show_idle_time(struct device *dev,
  90                                struct device_attribute *attr, char *buf)
  91{
  92        unsigned 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, "%lu\n", idle_time >> 12);
 113}
 114DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL);
 115
 116u64 arch_cpu_idle_time(int cpu)
 117{
 118        struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
 119        unsigned 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
 139void arch_cpu_idle_enter(void)
 140{
 141}
 142
 143void arch_cpu_idle_exit(void)
 144{
 145}
 146
 147void arch_cpu_idle_dead(void)
 148{
 149        cpu_die();
 150}
 151