/* * Idle daemon for PowerPC. Idle daemon will handle any action * that needs to be taken when the system becomes idle. * * Originally written by Cort Dougan (cort@cs.nmt.edu). * Subsequent 32-bit hacking by Tom Rini, Armin Kuster, * Paul Mackerras and others. * * iSeries supported added by Mike Corrigan <mikejc@us.ibm.com> * * Additional shared processor, SMT, and firmware support * Copyright (c) 2003 Dave Engebretsen <engebret@us.ibm.com> * * 32-bit and 64-bit versions merged by Paul Mackerras <paulus@samba.org> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/sched.h> #include <linux/kernel.h> #include <linux/smp.h> #include <linux/cpu.h> #include <linux/sysctl.h> #include <linux/tick.h> #include <asm/system.h> #include <asm/processor.h> #include <asm/cputable.h> #include <asm/time.h> #include <asm/machdep.h> #include <asm/smp.h> #ifdef CONFIG_HOTPLUG_CPU #define cpu_should_die() cpu_is_offline(smp_processor_id()) #else #define cpu_should_die() 0 #endif static int __init powersave_off(char *arg) { ppc_md.power_save = NULL; return 0; } __setup("powersave=off", powersave_off); /* * The body of the idle task. */ void cpu_idle(void) { if (ppc_md.idle_loop) ppc_md.idle_loop(); /* doesn't return */ set_thread_flag(TIF_POLLING_NRFLAG); while (1) { tick_nohz_stop_sched_tick(1); while (!need_resched() && !cpu_should_die()) { ppc64_runlatch_off(); if (ppc_md.power_save) { clear_thread_flag(TIF_POLLING_NRFLAG); /* * smp_mb is so clearing of TIF_POLLING_NRFLAG * is ordered w.r.t. need_resched() test. */ smp_mb(); local_irq_disable(); /* check again after disabling irqs */ if (!need_resched() && !cpu_should_die()) ppc_md.power_save(); local_irq_enable(); set_thread_flag(TIF_POLLING_NRFLAG); } else { /* * Go into low thread priority and possibly * low power mode. */ HMT_low(); HMT_very_low(); } } HMT_medium(); ppc64_runlatch_on(); tick_nohz_restart_sched_tick(); if (cpu_should_die()) cpu_die(); preempt_enable_no_resched(); schedule(); preempt_disable(); } } int powersave_nap; #ifdef CONFIG_SYSCTL /* * Register the sysctl to set/clear powersave_nap. */ static ctl_table powersave_nap_ctl_table[]={ { .ctl_name = KERN_PPC_POWERSAVE_NAP, .procname = "powersave-nap", .data = &powersave_nap, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &proc_dointvec, }, {} }; static ctl_table powersave_nap_sysctl_root[] = { { .ctl_name = CTL_KERN, .procname = "kernel", .mode = 0555, .child = powersave_nap_ctl_table, }, {} }; static int __init register_powersave_nap_sysctl(void) { register_sysctl_table(powersave_nap_sysctl_root); return 0; } __initcall(register_powersave_nap_sysctl); #endif