arch/powerpc/kernel/idle.c

   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_disable();
  56         } else {
  57                 /*
  58                  * Go into low thread priority and possibly
  59                  * low power mode.
  60                  */
  61                 HMT_low();
  62                 HMT_very_low();
  63         }
  64
  65         HMT_medium();
  66         ppc64_runlatch_on();
  67 }
  68
  69 int powersave_nap;
  70
  71 #ifdef CONFIG_PPC_970_NAP
  72 void power4_idle(void)
  73 {
  74         if (!cpu_has_feature(CPU_FTR_CAN_NAP))
  75                 return;
  76
  77         if (!powersave_nap)
  78                 return;
  79
  80         if (!prep_irq_for_idle())
  81                 return;
  82
  83         if (cpu_has_feature(CPU_FTR_ALTIVEC))
  84                 asm volatile(PPC_DSSALL " ; sync" ::: "memory");
  85
  86         power4_idle_nap();
  87
  88         /*
  89          * power4_idle_nap returns with interrupts enabled (soft and hard).
  90          * to our caller with interrupts enabled (soft and hard). Our caller
  91          * can cope with either interrupts disabled or enabled upon return.
  92          */
  93 }
  94 #endif
  95
  96 #ifdef CONFIG_SYSCTL
  97 /*
  98  * Register the sysctl to set/clear powersave_nap.
  99  */
 100 static struct ctl_table powersave_nap_ctl_table[] = {
 101         {
 102                 .procname       = "powersave-nap",
 103                 .data           = &powersave_nap,
 104                 .maxlen         = sizeof(int),
 105                 .mode           = 0644,
 106                 .proc_handler   = proc_dointvec,
 107         },
 108 };
 109
 110 static int __init
 111 register_powersave_nap_sysctl(void)
 112 {
 113         register_sysctl("kernel", powersave_nap_ctl_table);
 114
 115         return 0;
 116 }
 117 __initcall(register_powersave_nap_sysctl);
 118 #endif