| /* |
| * 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 |
| |
| unsigned long cpuidle_disable = IDLE_NO_OVERRIDE; |
| EXPORT_SYMBOL(cpuidle_disable); |
| |
| static int __init powersave_off(char *arg) |
| { |
| ppc_md.power_save = NULL; |
| cpuidle_disable = IDLE_POWERSAVE_OFF; |
| 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_idle_enter(); |
| rcu_idle_enter(); |
| |
| 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(); |
| |
| /* Don't trace irqs off for idle */ |
| stop_critical_timings(); |
| |
| /* check again after disabling irqs */ |
| if (!need_resched() && !cpu_should_die()) |
| ppc_md.power_save(); |
| |
| start_critical_timings(); |
| |
| 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(); |
| rcu_idle_exit(); |
| tick_nohz_idle_exit(); |
| preempt_enable_no_resched(); |
| if (cpu_should_die()) |
| cpu_die(); |
| schedule(); |
| preempt_disable(); |
| } |
| } |
| |
| static void do_nothing(void *unused) |
| { |
| } |
| |
| /* |
| * cpu_idle_wait - Used to ensure that all the CPUs come out of the old |
| * idle loop and start using the new idle loop. |
| * Required while changing idle handler on SMP systems. |
| * Caller must have changed idle handler to the new value before the call. |
| * This window may be larger on shared systems. |
| */ |
| void cpu_idle_wait(void) |
| { |
| smp_mb(); |
| /* kick all the CPUs so that they exit out of pm_idle */ |
| smp_call_function(do_nothing, NULL, 1); |
| } |
| EXPORT_SYMBOL_GPL(cpu_idle_wait); |
| |
| int powersave_nap; |
| |
| #ifdef CONFIG_SYSCTL |
| /* |
| * Register the sysctl to set/clear powersave_nap. |
| */ |
| static ctl_table powersave_nap_ctl_table[]={ |
| { |
| .procname = "powersave-nap", |
| .data = &powersave_nap, |
| .maxlen = sizeof(int), |
| .mode = 0644, |
| .proc_handler = proc_dointvec, |
| }, |
| {} |
| }; |
| static ctl_table powersave_nap_sysctl_root[] = { |
| { |
| .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 |