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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Idle daemon for PowerPC. Idle daemon will handle any action
4 * that needs to be taken when the system becomes idle.
5 *
6 * Originally written by Cort Dougan (cort@cs.nmt.edu).
7 * Subsequent 32-bit hacking by Tom Rini, Armin Kuster,
8 * Paul Mackerras and others.
9 *
10 * iSeries supported added by Mike Corrigan <mikejc@us.ibm.com>
11 *
12 * Additional shared processor, SMT, and firmware support
13 * Copyright (c) 2003 Dave Engebretsen <engebret@us.ibm.com>
14 *
15 * 32-bit and 64-bit versions merged by Paul Mackerras <paulus@samba.org>
16 */
17
18#include <linux/sched.h>
19#include <linux/kernel.h>
20#include <linux/smp.h>
21#include <linux/cpu.h>
22#include <linux/sysctl.h>
23#include <linux/tick.h>
24
25#include <asm/processor.h>
26#include <asm/cputable.h>
27#include <asm/time.h>
28#include <asm/machdep.h>
29#include <asm/runlatch.h>
30#include <asm/smp.h>
31
32
33unsigned long cpuidle_disable = IDLE_NO_OVERRIDE;
34EXPORT_SYMBOL(cpuidle_disable);
35
36static int __init powersave_off(char *arg)
37{
38 ppc_md.power_save = NULL;
39 cpuidle_disable = IDLE_POWERSAVE_OFF;
40 return 0;
41}
42__setup("powersave=off", powersave_off);
43
44#ifdef CONFIG_HOTPLUG_CPU
45void arch_cpu_idle_dead(void)
46{
47 sched_preempt_enable_no_resched();
48 cpu_die();
49}
50#endif
51
52void arch_cpu_idle(void)
53{
54 ppc64_runlatch_off();
55
56 if (ppc_md.power_save) {
57 ppc_md.power_save();
58 /*
59 * Some power_save functions return with
60 * interrupts enabled, some don't.
61 */
62 if (irqs_disabled())
63 local_irq_enable();
64 } else {
65 local_irq_enable();
66 /*
67 * Go into low thread priority and possibly
68 * low power mode.
69 */
70 HMT_low();
71 HMT_very_low();
72 }
73
74 HMT_medium();
75 ppc64_runlatch_on();
76}
77
78int powersave_nap;
79
80#ifdef CONFIG_PPC_970_NAP
81void power4_idle(void)
82{
83 if (!cpu_has_feature(CPU_FTR_CAN_NAP))
84 return;
85
86 if (!powersave_nap)
87 return;
88
89 if (!prep_irq_for_idle())
90 return;
91
92 if (cpu_has_feature(CPU_FTR_ALTIVEC))
93 asm volatile("DSSALL ; sync" ::: "memory");
94
95 power4_idle_nap();
96
97 /*
98 * power4_idle_nap returns with interrupts enabled (soft and hard).
99 * to our caller with interrupts enabled (soft and hard). Our caller
100 * can cope with either interrupts disabled or enabled upon return.
101 */
102}
103#endif
104
105#ifdef CONFIG_SYSCTL
106/*
107 * Register the sysctl to set/clear powersave_nap.
108 */
109static struct ctl_table powersave_nap_ctl_table[] = {
110 {
111 .procname = "powersave-nap",
112 .data = &powersave_nap,
113 .maxlen = sizeof(int),
114 .mode = 0644,
115 .proc_handler = proc_dointvec,
116 },
117 {}
118};
119static struct ctl_table powersave_nap_sysctl_root[] = {
120 {
121 .procname = "kernel",
122 .mode = 0555,
123 .child = powersave_nap_ctl_table,
124 },
125 {}
126};
127
128static int __init
129register_powersave_nap_sysctl(void)
130{
131 register_sysctl_table(powersave_nap_sysctl_root);
132
133 return 0;
134}
135__initcall(register_powersave_nap_sysctl);
136#endif
1/*
2 * Idle daemon for PowerPC. Idle daemon will handle any action
3 * that needs to be taken when the system becomes idle.
4 *
5 * Originally written by Cort Dougan (cort@cs.nmt.edu).
6 * Subsequent 32-bit hacking by Tom Rini, Armin Kuster,
7 * Paul Mackerras and others.
8 *
9 * iSeries supported added by Mike Corrigan <mikejc@us.ibm.com>
10 *
11 * Additional shared processor, SMT, and firmware support
12 * Copyright (c) 2003 Dave Engebretsen <engebret@us.ibm.com>
13 *
14 * 32-bit and 64-bit versions merged by Paul Mackerras <paulus@samba.org>
15 *
16 * This program is free software; you can redistribute it and/or
17 * modify it under the terms of the GNU General Public License
18 * as published by the Free Software Foundation; either version
19 * 2 of the License, or (at your option) any later version.
20 */
21
22#include <linux/sched.h>
23#include <linux/kernel.h>
24#include <linux/smp.h>
25#include <linux/cpu.h>
26#include <linux/sysctl.h>
27#include <linux/tick.h>
28
29#include <asm/system.h>
30#include <asm/processor.h>
31#include <asm/cputable.h>
32#include <asm/time.h>
33#include <asm/machdep.h>
34#include <asm/smp.h>
35
36#ifdef CONFIG_HOTPLUG_CPU
37#define cpu_should_die() cpu_is_offline(smp_processor_id())
38#else
39#define cpu_should_die() 0
40#endif
41
42static int __init powersave_off(char *arg)
43{
44 ppc_md.power_save = NULL;
45 return 0;
46}
47__setup("powersave=off", powersave_off);
48
49/*
50 * The body of the idle task.
51 */
52void cpu_idle(void)
53{
54 if (ppc_md.idle_loop)
55 ppc_md.idle_loop(); /* doesn't return */
56
57 set_thread_flag(TIF_POLLING_NRFLAG);
58 while (1) {
59 tick_nohz_stop_sched_tick(1);
60 while (!need_resched() && !cpu_should_die()) {
61 ppc64_runlatch_off();
62
63 if (ppc_md.power_save) {
64 clear_thread_flag(TIF_POLLING_NRFLAG);
65 /*
66 * smp_mb is so clearing of TIF_POLLING_NRFLAG
67 * is ordered w.r.t. need_resched() test.
68 */
69 smp_mb();
70 local_irq_disable();
71
72 /* Don't trace irqs off for idle */
73 stop_critical_timings();
74
75 /* check again after disabling irqs */
76 if (!need_resched() && !cpu_should_die())
77 ppc_md.power_save();
78
79 start_critical_timings();
80
81 local_irq_enable();
82 set_thread_flag(TIF_POLLING_NRFLAG);
83
84 } else {
85 /*
86 * Go into low thread priority and possibly
87 * low power mode.
88 */
89 HMT_low();
90 HMT_very_low();
91 }
92 }
93
94 HMT_medium();
95 ppc64_runlatch_on();
96 tick_nohz_restart_sched_tick();
97 preempt_enable_no_resched();
98 if (cpu_should_die())
99 cpu_die();
100 schedule();
101 preempt_disable();
102 }
103}
104
105int powersave_nap;
106
107#ifdef CONFIG_SYSCTL
108/*
109 * Register the sysctl to set/clear powersave_nap.
110 */
111static ctl_table powersave_nap_ctl_table[]={
112 {
113 .procname = "powersave-nap",
114 .data = &powersave_nap,
115 .maxlen = sizeof(int),
116 .mode = 0644,
117 .proc_handler = proc_dointvec,
118 },
119 {}
120};
121static ctl_table powersave_nap_sysctl_root[] = {
122 {
123 .procname = "kernel",
124 .mode = 0555,
125 .child = powersave_nap_ctl_table,
126 },
127 {}
128};
129
130static int __init
131register_powersave_nap_sysctl(void)
132{
133 register_sysctl_table(powersave_nap_sysctl_root);
134
135 return 0;
136}
137__initcall(register_powersave_nap_sysctl);
138#endif