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 1;
41}
42__setup("powersave=off", powersave_off);
43
44void arch_cpu_idle(void)
45{
46 ppc64_runlatch_off();
47
48 if (ppc_md.power_save) {
49 ppc_md.power_save();
50 /*
51 * Some power_save functions return with
52 * interrupts enabled, some don't.
53 */
54 if (!irqs_disabled())
55 raw_local_irq_disable();
56 } else {
57 /*
58 * Go into low thread priority and possibly
59 * low power mode.
60 */
61 HMT_low();
62 HMT_very_low();
63 }
64
65 HMT_medium();
66 ppc64_runlatch_on();
67}
68
69int powersave_nap;
70
71#ifdef CONFIG_PPC_970_NAP
72void power4_idle(void)
73{
74 if (!cpu_has_feature(CPU_FTR_CAN_NAP))
75 return;
76
77 if (!powersave_nap)
78 return;
79
80 if (!prep_irq_for_idle())
81 return;
82
83 if (cpu_has_feature(CPU_FTR_ALTIVEC))
84 asm volatile(PPC_DSSALL " ; sync" ::: "memory");
85
86 power4_idle_nap();
87
88 /*
89 * power4_idle_nap returns with interrupts enabled (soft and hard).
90 * to our caller with interrupts enabled (soft and hard). Our caller
91 * can cope with either interrupts disabled or enabled upon return.
92 */
93}
94#endif
95
96#ifdef CONFIG_SYSCTL
97/*
98 * Register the sysctl to set/clear powersave_nap.
99 */
100static const struct ctl_table powersave_nap_ctl_table[] = {
101 {
102 .procname = "powersave-nap",
103 .data = &powersave_nap,
104 .maxlen = sizeof(int),
105 .mode = 0644,
106 .proc_handler = proc_dointvec,
107 },
108};
109
110static int __init
111register_powersave_nap_sysctl(void)
112{
113 register_sysctl("kernel", powersave_nap_ctl_table);
114
115 return 0;
116}
117__initcall(register_powersave_nap_sysctl);
118#endif
119

source code of linux/arch/powerpc/kernel/idle.c