xref: /openbmc/linux/arch/powerpc/kernel/idle.c (revision b3fd7368f8f60bc9a7ffc2a5311db5f4dbd42180)
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/processor.h>
30  #include <asm/cputable.h>
31  #include <asm/time.h>
32  #include <asm/machdep.h>
33  #include <asm/runlatch.h>
34  #include <asm/smp.h>
35  
36  
37  unsigned long cpuidle_disable = IDLE_NO_OVERRIDE;
38  EXPORT_SYMBOL(cpuidle_disable);
39  
40  static int __init powersave_off(char *arg)
41  {
42  	ppc_md.power_save = NULL;
43  	cpuidle_disable = IDLE_POWERSAVE_OFF;
44  	return 0;
45  }
46  __setup("powersave=off", powersave_off);
47  
48  #ifdef CONFIG_HOTPLUG_CPU
49  void arch_cpu_idle_dead(void)
50  {
51  	sched_preempt_enable_no_resched();
52  	cpu_die();
53  }
54  #endif
55  
56  void arch_cpu_idle(void)
57  {
58  	ppc64_runlatch_off();
59  
60  	if (ppc_md.power_save) {
61  		ppc_md.power_save();
62  		/*
63  		 * Some power_save functions return with
64  		 * interrupts enabled, some don't.
65  		 */
66  		if (irqs_disabled())
67  			local_irq_enable();
68  	} else {
69  		local_irq_enable();
70  		/*
71  		 * Go into low thread priority and possibly
72  		 * low power mode.
73  		 */
74  		HMT_low();
75  		HMT_very_low();
76  	}
77  
78  	HMT_medium();
79  	ppc64_runlatch_on();
80  }
81  
82  int powersave_nap;
83  
84  #ifdef CONFIG_SYSCTL
85  /*
86   * Register the sysctl to set/clear powersave_nap.
87   */
88  static struct ctl_table powersave_nap_ctl_table[] = {
89  	{
90  		.procname	= "powersave-nap",
91  		.data		= &powersave_nap,
92  		.maxlen		= sizeof(int),
93  		.mode		= 0644,
94  		.proc_handler	= proc_dointvec,
95  	},
96  	{}
97  };
98  static struct ctl_table powersave_nap_sysctl_root[] = {
99  	{
100  		.procname	= "kernel",
101  		.mode		= 0555,
102  		.child		= powersave_nap_ctl_table,
103  	},
104  	{}
105  };
106  
107  static int __init
108  register_powersave_nap_sysctl(void)
109  {
110  	register_sysctl_table(powersave_nap_sysctl_root);
111  
112  	return 0;
113  }
114  __initcall(register_powersave_nap_sysctl);
115  #endif
116