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 0;
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_enable();
56 	} else {
57 		raw_local_irq_enable();
58 		/*
59 		 * Go into low thread priority and possibly
60 		 * low power mode.
61 		 */
62 		HMT_low();
63 		HMT_very_low();
64 	}
65 
66 	HMT_medium();
67 	ppc64_runlatch_on();
68 }
69 
70 int powersave_nap;
71 
72 #ifdef CONFIG_PPC_970_NAP
power4_idle(void)73 void power4_idle(void)
74 {
75 	if (!cpu_has_feature(CPU_FTR_CAN_NAP))
76 		return;
77 
78 	if (!powersave_nap)
79 		return;
80 
81 	if (!prep_irq_for_idle())
82 		return;
83 
84 	if (cpu_has_feature(CPU_FTR_ALTIVEC))
85 		asm volatile("DSSALL ; sync" ::: "memory");
86 
87 	power4_idle_nap();
88 
89 	/*
90 	 * power4_idle_nap returns with interrupts enabled (soft and hard).
91 	 * to our caller with interrupts enabled (soft and hard). Our caller
92 	 * can cope with either interrupts disabled or enabled upon return.
93 	 */
94 }
95 #endif
96 
97 #ifdef CONFIG_SYSCTL
98 /*
99  * Register the sysctl to set/clear powersave_nap.
100  */
101 static struct ctl_table powersave_nap_ctl_table[] = {
102 	{
103 		.procname	= "powersave-nap",
104 		.data		= &powersave_nap,
105 		.maxlen		= sizeof(int),
106 		.mode		= 0644,
107 		.proc_handler	= proc_dointvec,
108 	},
109 	{}
110 };
111 static struct ctl_table powersave_nap_sysctl_root[] = {
112 	{
113 		.procname	= "kernel",
114 		.mode		= 0555,
115 		.child		= powersave_nap_ctl_table,
116 	},
117 	{}
118 };
119 
120 static int __init
register_powersave_nap_sysctl(void)121 register_powersave_nap_sysctl(void)
122 {
123 	register_sysctl_table(powersave_nap_sysctl_root);
124 
125 	return 0;
126 }
127 __initcall(register_powersave_nap_sysctl);
128 #endif
129