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 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 44 #ifdef CONFIG_HOTPLUG_CPU 45 void arch_cpu_idle_dead(void) 46 { 47 sched_preempt_enable_no_resched(); 48 cpu_die(); 49 } 50 #endif 51 52 void arch_cpu_idle(void) 53 { 54 ppc64_runlatch_off(); 55 56 if (ppc_md.power_save) { 57 ppc_md.power_save(); 58 /* 59 * Some power_save functions return with 60 * interrupts enabled, some don't. 61 */ 62 if (irqs_disabled()) 63 local_irq_enable(); 64 } else { 65 local_irq_enable(); 66 /* 67 * Go into low thread priority and possibly 68 * low power mode. 69 */ 70 HMT_low(); 71 HMT_very_low(); 72 } 73 74 HMT_medium(); 75 ppc64_runlatch_on(); 76 } 77 78 int powersave_nap; 79 80 #ifdef CONFIG_PPC_970_NAP 81 void power4_idle(void) 82 { 83 if (!cpu_has_feature(CPU_FTR_CAN_NAP)) 84 return; 85 86 if (!powersave_nap) 87 return; 88 89 if (!prep_irq_for_idle()) 90 return; 91 92 if (cpu_has_feature(CPU_FTR_ALTIVEC)) 93 asm volatile("DSSALL ; sync" ::: "memory"); 94 95 power4_idle_nap(); 96 97 /* 98 * power4_idle_nap returns with interrupts enabled (soft and hard). 99 * to our caller with interrupts enabled (soft and hard). Our caller 100 * can cope with either interrupts disabled or enabled upon return. 101 */ 102 } 103 #endif 104 105 #ifdef CONFIG_SYSCTL 106 /* 107 * Register the sysctl to set/clear powersave_nap. 108 */ 109 static struct ctl_table powersave_nap_ctl_table[] = { 110 { 111 .procname = "powersave-nap", 112 .data = &powersave_nap, 113 .maxlen = sizeof(int), 114 .mode = 0644, 115 .proc_handler = proc_dointvec, 116 }, 117 {} 118 }; 119 static struct ctl_table powersave_nap_sysctl_root[] = { 120 { 121 .procname = "kernel", 122 .mode = 0555, 123 .child = powersave_nap_ctl_table, 124 }, 125 {} 126 }; 127 128 static int __init 129 register_powersave_nap_sysctl(void) 130 { 131 register_sysctl_table(powersave_nap_sysctl_root); 132 133 return 0; 134 } 135 __initcall(register_powersave_nap_sysctl); 136 #endif 137