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
enabled_wait(void)24 void enabled_wait(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 }
50 NOKPROBE_SYMBOL(enabled_wait);
51
show_idle_count(struct device * dev,struct device_attribute * attr,char * buf)52 static 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 }
67 DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
68
show_idle_time(struct device * dev,struct device_attribute * attr,char * buf)69 static 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 }
94 DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL);
95
arch_cpu_idle_time(int cpu)96 u64 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
arch_cpu_idle_enter(void)119 void arch_cpu_idle_enter(void)
120 {
121 }
122
arch_cpu_idle(void)123 void arch_cpu_idle(void)
124 {
125 enabled_wait();
126 raw_local_irq_enable();
127 }
128
arch_cpu_idle_exit(void)129 void arch_cpu_idle_exit(void)
130 {
131 }
132
arch_cpu_idle_dead(void)133 void arch_cpu_idle_dead(void)
134 {
135 cpu_die();
136 }
137