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 0;
  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_enable();
  56         } else {
  57                 raw_local_irq_enable();
  58                 /*
  59                  * Go into low thread priority and possibly
  60                  * low power mode.
  61                  */
  62                 HMT_low();
  63                 HMT_very_low();
  64         }
  65
  66         HMT_medium();
  67         ppc64_runlatch_on();
  68 }
  69
  70 int powersave_nap;
  71
  72 #ifdef CONFIG_PPC_970_NAP
  73 void power4_idle(void)
  74 {
  75         if (!cpu_has_feature(CPU_FTR_CAN_NAP))
  76                 return;
  77
  78         if (!powersave_nap)
  79                 return;
  80
  81         if (!prep_irq_for_idle())
  82                 return;
  83
  84         if (cpu_has_feature(CPU_FTR_ALTIVEC))
  85                 asm volatile("DSSALL ; sync" ::: "memory");
  86
  87         power4_idle_nap();
  88
  89         /*
  90          * power4_idle_nap returns with interrupts enabled (soft and hard).
  91          * to our caller with interrupts enabled (soft and hard). Our caller
  92          * can cope with either interrupts disabled or enabled upon return.
  93          */
  94 }
  95 #endif
  96
  97 #ifdef CONFIG_SYSCTL
  98 /*
  99  * Register the sysctl to set/clear powersave_nap.
 100  */
 101 static struct ctl_table powersave_nap_ctl_table[] = {
 102         {
 103                 .procname       = "powersave-nap",
 104                 .data           = &powersave_nap,
 105                 .maxlen         = sizeof(int),
 106                 .mode           = 0644,
 107                 .proc_handler   = proc_dointvec,
 108         },
 109         {}
 110 };
 111 static struct ctl_table powersave_nap_sysctl_root[] = {
 112         {
 113                 .procname       = "kernel",
 114                 .mode           = 0555,
 115                 .child          = powersave_nap_ctl_table,
 116         },
 117         {}
 118 };
 119
 120 static int __init
 121 register_powersave_nap_sysctl(void)
 122 {
 123         register_sysctl_table(powersave_nap_sysctl_root);
 124
 125         return 0;
 126 }
 127 __initcall(register_powersave_nap_sysctl);
 128 #endif