xref: /openbmc/linux/arch/powerpc/kernel/idle.c (revision bfedee5d)
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 
33 unsigned long cpuidle_disable = IDLE_NO_OVERRIDE;
34 EXPORT_SYMBOL(cpuidle_disable);
35 
powersave_off(char * arg)36 static 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 
arch_cpu_idle(void)44 void 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 
69 int powersave_nap;
70 
71 #ifdef CONFIG_PPC_970_NAP
power4_idle(void)72 void 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  */
100 static 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 };
110 
111 static int __init
register_powersave_nap_sysctl(void)112 register_powersave_nap_sysctl(void)
113 {
114 	register_sysctl("kernel", powersave_nap_ctl_table);
115 
116 	return 0;
117 }
118 __initcall(register_powersave_nap_sysctl);
119 #endif
120