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/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 <asm/nmi.h>
  18#include <asm/smp.h>
  19#include "entry.h"
  20
  21static DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
  22
  23void enabled_wait(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        trace_hardirqs_on();
  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        /* Call the assembler magic in entry.S */
  37        psw_idle(idle, psw_mask);
  38
  39        trace_hardirqs_off();
  40
  41        /* Account time spent with enabled wait psw loaded as idle time. */
  42        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        write_seqcount_end(&idle->seqcount);
  49}
  50NOKPROBE_SYMBOL(enabled_wait);
  51
  52static ssize_t show_idle_count(struct device *dev,
  53                                struct device_attribute *attr, char *buf)
  54{
  55        struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
  56        unsigned long long idle_count;
  57        unsigned int seq;
  58
  59        do {
  60                seq = read_seqcount_begin(&idle->seqcount);
  61                idle_count = READ_ONCE(idle->idle_count);
  62                if (READ_ONCE(idle->clock_idle_enter))
  63                        idle_count++;
  64        } while (read_seqcount_retry(&idle->seqcount, seq));
  65        return sprintf(buf, "%llu\n", idle_count);
  66}
  67DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
  68
  69static ssize_t show_idle_time(struct device *dev,
  70                                struct device_attribute *attr, char *buf)
  71{
  72        unsigned long long now, idle_time, idle_enter, idle_exit, in_idle;
  73        struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
  74        unsigned int seq;
  75
  76        do {
  77                seq = read_seqcount_begin(&idle->seqcount);
  78                idle_time = READ_ONCE(idle->idle_time);
  79                idle_enter = READ_ONCE(idle->clock_idle_enter);
  80                idle_exit = READ_ONCE(idle->clock_idle_exit);
  81        } while (read_seqcount_retry(&idle->seqcount, seq));
  82        in_idle = 0;
  83        now = get_tod_clock();
  84        if (idle_enter) {
  85                if (idle_exit) {
  86                        in_idle = idle_exit - idle_enter;
  87                } else if (now > idle_enter) {
  88                        in_idle = now - idle_enter;
  89                }
  90        }
  91        idle_time += in_idle;
  92        return sprintf(buf, "%llu\n", idle_time >> 12);
  93}
  94DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL);
  95
  96u64 arch_cpu_idle_time(int cpu)
  97{
  98        struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
  99        unsigned long long now, idle_enter, idle_exit, in_idle;
 100        unsigned int seq;
 101
 102        do {
 103                seq = read_seqcount_begin(&idle->seqcount);
 104                idle_enter = READ_ONCE(idle->clock_idle_enter);
 105                idle_exit = READ_ONCE(idle->clock_idle_exit);
 106        } while (read_seqcount_retry(&idle->seqcount, seq));
 107        in_idle = 0;
 108        now = get_tod_clock();
 109        if (idle_enter) {
 110                if (idle_exit) {
 111                        in_idle = idle_exit - idle_enter;
 112                } else if (now > idle_enter) {
 113                        in_idle = now - idle_enter;
 114                }
 115        }
 116        return cputime_to_nsecs(in_idle);
 117}
 118
 119void arch_cpu_idle_enter(void)
 120{
 121        local_mcck_disable();
 122}
 123
 124void arch_cpu_idle(void)
 125{
 126        if (!test_cpu_flag(CIF_MCCK_PENDING))
 127                /* Halt the cpu and keep track of cpu time accounting. */
 128                enabled_wait();
 129        local_irq_enable();
 130}
 131
 132void arch_cpu_idle_exit(void)
 133{
 134        local_mcck_enable();
 135        if (test_cpu_flag(CIF_MCCK_PENDING))
 136                s390_handle_mcck();
 137}
 138
 139void arch_cpu_idle_dead(void)
 140{
 141        cpu_die();
 142}
 143