| 1 | /* |
| 2 | * Idle daemon for PowerPC. Idle daemon will handle any action |
| 3 | * that needs to be taken when the system becomes idle. |
| 4 | * |
| 5 | * Originally written by Cort Dougan (cort@cs.nmt.edu). |
| 6 | * Subsequent 32-bit hacking by Tom Rini, Armin Kuster, |
| 7 | * Paul Mackerras and others. |
| 8 | * |
| 9 | * iSeries supported added by Mike Corrigan <mikejc@us.ibm.com> |
| 10 | * |
| 11 | * Additional shared processor, SMT, and firmware support |
| 12 | * Copyright (c) 2003 Dave Engebretsen <engebret@us.ibm.com> |
| 13 | * |
| 14 | * 32-bit and 64-bit versions merged by Paul Mackerras <paulus@samba.org> |
| 15 | * |
| 16 | * This program is free software; you can redistribute it and/or |
| 17 | * modify it under the terms of the GNU General Public License |
| 18 | * as published by the Free Software Foundation; either version |
| 19 | * 2 of the License, or (at your option) any later version. |
| 20 | */ |
| 21 | |
| 22 | #include <linux/sched.h> |
| 23 | #include <linux/kernel.h> |
| 24 | #include <linux/smp.h> |
| 25 | #include <linux/cpu.h> |
| 26 | #include <linux/sysctl.h> |
| 27 | #include <linux/tick.h> |
| 28 | |
| 29 | #include <asm/system.h> |
| 30 | #include <asm/processor.h> |
| 31 | #include <asm/cputable.h> |
| 32 | #include <asm/time.h> |
| 33 | #include <asm/machdep.h> |
| 34 | #include <asm/smp.h> |
| 35 | |
| 36 | #ifdef CONFIG_HOTPLUG_CPU |
| 37 | #define cpu_should_die() cpu_is_offline(smp_processor_id()) |
| 38 | #else |
| 39 | #define cpu_should_die() 0 |
| 40 | #endif |
| 41 | |
| 42 | static int __init powersave_off(char *arg) |
| 43 | { |
| 44 | ppc_md.power_save = NULL; |
| 45 | return 0; |
| 46 | } |
| 47 | __setup("powersave=off", powersave_off); |
| 48 | |
| 49 | /* |
| 50 | * The body of the idle task. |
| 51 | */ |
| 52 | void cpu_idle(void) |
| 53 | { |
| 54 | if (ppc_md.idle_loop) |
| 55 | ppc_md.idle_loop(); /* doesn't return */ |
| 56 | |
| 57 | set_thread_flag(TIF_POLLING_NRFLAG); |
| 58 | while (1) { |
| 59 | tick_nohz_stop_sched_tick(1); |
| 60 | while (!need_resched() && !cpu_should_die()) { |
| 61 | ppc64_runlatch_off(); |
| 62 | |
| 63 | if (ppc_md.power_save) { |
| 64 | clear_thread_flag(TIF_POLLING_NRFLAG); |
| 65 | /* |
| 66 | * smp_mb is so clearing of TIF_POLLING_NRFLAG |
| 67 | * is ordered w.r.t. need_resched() test. |
| 68 | */ |
| 69 | smp_mb(); |
| 70 | local_irq_disable(); |
| 71 | |
| 72 | /* Don't trace irqs off for idle */ |
| 73 | stop_critical_timings(); |
| 74 | |
| 75 | /* check again after disabling irqs */ |
| 76 | if (!need_resched() && !cpu_should_die()) |
| 77 | ppc_md.power_save(); |
| 78 | |
| 79 | start_critical_timings(); |
| 80 | |
| 81 | local_irq_enable(); |
| 82 | set_thread_flag(TIF_POLLING_NRFLAG); |
| 83 | |
| 84 | } else { |
| 85 | /* |
| 86 | * Go into low thread priority and possibly |
| 87 | * low power mode. |
| 88 | */ |
| 89 | HMT_low(); |
| 90 | HMT_very_low(); |
| 91 | } |
| 92 | } |
| 93 | |
| 94 | HMT_medium(); |
| 95 | ppc64_runlatch_on(); |
| 96 | tick_nohz_restart_sched_tick(); |
| 97 | preempt_enable_no_resched(); |
| 98 | if (cpu_should_die()) |
| 99 | cpu_die(); |
| 100 | schedule(); |
| 101 | preempt_disable(); |
| 102 | } |
| 103 | } |
| 104 | |
| 105 | int powersave_nap; |
| 106 | |
| 107 | #ifdef CONFIG_SYSCTL |
| 108 | /* |
| 109 | * Register the sysctl to set/clear powersave_nap. |
| 110 | */ |
| 111 | static ctl_table powersave_nap_ctl_table[]={ |
| 112 | { |
| 113 | .procname = "powersave-nap", |
| 114 | .data = &powersave_nap, |
| 115 | .maxlen = sizeof(int), |
| 116 | .mode = 0644, |
| 117 | .proc_handler = proc_dointvec, |
| 118 | }, |
| 119 | {} |
| 120 | }; |
| 121 | static ctl_table powersave_nap_sysctl_root[] = { |
| 122 | { |
| 123 | .procname = "kernel", |
| 124 | .mode = 0555, |
| 125 | .child = powersave_nap_ctl_table, |
| 126 | }, |
| 127 | {} |
| 128 | }; |
| 129 | |
| 130 | static int __init |
| 131 | register_powersave_nap_sysctl(void) |
| 132 | { |
| 133 | register_sysctl_table(powersave_nap_sysctl_root); |
| 134 | |
| 135 | return 0; |
| 136 | } |
| 137 | __initcall(register_powersave_nap_sysctl); |
| 138 | #endif |