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