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 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