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 1; 41 } 42 __setup("powersave=off", powersave_off); 43 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 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 static int __init 111 register_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