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_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 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(PPC_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 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