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-rw-r--r--arch/ppc64/kernel/idle.c380
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diff --git a/arch/ppc64/kernel/idle.c b/arch/ppc64/kernel/idle.c
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+/*
+ * 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)
+ *
+ * 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>
+ *
+ * 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/config.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/smp.h>
+#include <linux/cpu.h>
+#include <linux/module.h>
+#include <linux/sysctl.h>
+#include <linux/smp.h>
+
+#include <asm/system.h>
+#include <asm/processor.h>
+#include <asm/mmu.h>
+#include <asm/cputable.h>
+#include <asm/time.h>
+#include <asm/iSeries/HvCall.h>
+#include <asm/iSeries/ItLpQueue.h>
+#include <asm/plpar_wrappers.h>
+#include <asm/systemcfg.h>
+
+extern void power4_idle(void);
+
+static int (*idle_loop)(void);
+
+#ifdef CONFIG_PPC_ISERIES
+static unsigned long maxYieldTime = 0;
+static unsigned long minYieldTime = 0xffffffffffffffffUL;
+
+static void yield_shared_processor(void)
+{
+ unsigned long tb;
+ unsigned long yieldTime;
+
+ HvCall_setEnabledInterrupts(HvCall_MaskIPI |
+ HvCall_MaskLpEvent |
+ HvCall_MaskLpProd |
+ HvCall_MaskTimeout);
+
+ tb = get_tb();
+ /* Compute future tb value when yield should expire */
+ HvCall_yieldProcessor(HvCall_YieldTimed, tb+tb_ticks_per_jiffy);
+
+ yieldTime = get_tb() - tb;
+ if (yieldTime > maxYieldTime)
+ maxYieldTime = yieldTime;
+
+ if (yieldTime < minYieldTime)
+ minYieldTime = yieldTime;
+
+ /*
+ * The decrementer stops during the yield. Force a fake decrementer
+ * here and let the timer_interrupt code sort out the actual time.
+ */
+ get_paca()->lppaca.int_dword.fields.decr_int = 1;
+ process_iSeries_events();
+}
+
+static int iSeries_idle(void)
+{
+ struct paca_struct *lpaca;
+ long oldval;
+ unsigned long CTRL;
+
+ /* ensure iSeries run light will be out when idle */
+ clear_thread_flag(TIF_RUN_LIGHT);
+ CTRL = mfspr(CTRLF);
+ CTRL &= ~RUNLATCH;
+ mtspr(CTRLT, CTRL);
+
+ lpaca = get_paca();
+
+ while (1) {
+ if (lpaca->lppaca.shared_proc) {
+ if (ItLpQueue_isLpIntPending(lpaca->lpqueue_ptr))
+ process_iSeries_events();
+ if (!need_resched())
+ yield_shared_processor();
+ } else {
+ oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
+
+ if (!oldval) {
+ set_thread_flag(TIF_POLLING_NRFLAG);
+
+ while (!need_resched()) {
+ HMT_medium();
+ if (ItLpQueue_isLpIntPending(lpaca->lpqueue_ptr))
+ process_iSeries_events();
+ HMT_low();
+ }
+
+ HMT_medium();
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ } else {
+ set_need_resched();
+ }
+ }
+
+ schedule();
+ }
+
+ return 0;
+}
+
+#else
+
+static int default_idle(void)
+{
+ long oldval;
+ unsigned int cpu = smp_processor_id();
+
+ while (1) {
+ oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
+
+ if (!oldval) {
+ set_thread_flag(TIF_POLLING_NRFLAG);
+
+ while (!need_resched() && !cpu_is_offline(cpu)) {
+ barrier();
+ /*
+ * Go into low thread priority and possibly
+ * low power mode.
+ */
+ HMT_low();
+ HMT_very_low();
+ }
+
+ HMT_medium();
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ } else {
+ set_need_resched();
+ }
+
+ schedule();
+ if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
+ cpu_die();
+ }
+
+ return 0;
+}
+
+#ifdef CONFIG_PPC_PSERIES
+
+DECLARE_PER_CPU(unsigned long, smt_snooze_delay);
+
+int dedicated_idle(void)
+{
+ long oldval;
+ struct paca_struct *lpaca = get_paca(), *ppaca;
+ unsigned long start_snooze;
+ unsigned long *smt_snooze_delay = &__get_cpu_var(smt_snooze_delay);
+ unsigned int cpu = smp_processor_id();
+
+ ppaca = &paca[cpu ^ 1];
+
+ while (1) {
+ /*
+ * Indicate to the HV that we are idle. Now would be
+ * a good time to find other work to dispatch.
+ */
+ lpaca->lppaca.idle = 1;
+
+ oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
+ if (!oldval) {
+ set_thread_flag(TIF_POLLING_NRFLAG);
+ start_snooze = __get_tb() +
+ *smt_snooze_delay * tb_ticks_per_usec;
+ while (!need_resched() && !cpu_is_offline(cpu)) {
+ /*
+ * Go into low thread priority and possibly
+ * low power mode.
+ */
+ HMT_low();
+ HMT_very_low();
+
+ if (*smt_snooze_delay == 0 ||
+ __get_tb() < start_snooze)
+ continue;
+
+ HMT_medium();
+
+ if (!(ppaca->lppaca.idle)) {
+ local_irq_disable();
+
+ /*
+ * We are about to sleep the thread
+ * and so wont be polling any
+ * more.
+ */
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+
+ /*
+ * SMT dynamic mode. Cede will result
+ * in this thread going dormant, if the
+ * partner thread is still doing work.
+ * Thread wakes up if partner goes idle,
+ * an interrupt is presented, or a prod
+ * occurs. Returning from the cede
+ * enables external interrupts.
+ */
+ if (!need_resched())
+ cede_processor();
+ else
+ local_irq_enable();
+ } else {
+ /*
+ * Give the HV an opportunity at the
+ * processor, since we are not doing
+ * any work.
+ */
+ poll_pending();
+ }
+ }
+
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ } else {
+ set_need_resched();
+ }
+
+ HMT_medium();
+ lpaca->lppaca.idle = 0;
+ schedule();
+ if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
+ cpu_die();
+ }
+ return 0;
+}
+
+static int shared_idle(void)
+{
+ struct paca_struct *lpaca = get_paca();
+ unsigned int cpu = smp_processor_id();
+
+ while (1) {
+ /*
+ * Indicate to the HV that we are idle. Now would be
+ * a good time to find other work to dispatch.
+ */
+ lpaca->lppaca.idle = 1;
+
+ while (!need_resched() && !cpu_is_offline(cpu)) {
+ local_irq_disable();
+
+ /*
+ * Yield the processor to the hypervisor. We return if
+ * an external interrupt occurs (which are driven prior
+ * to returning here) or if a prod occurs from another
+ * processor. When returning here, external interrupts
+ * are enabled.
+ *
+ * Check need_resched() again with interrupts disabled
+ * to avoid a race.
+ */
+ if (!need_resched())
+ cede_processor();
+ else
+ local_irq_enable();
+ }
+
+ HMT_medium();
+ lpaca->lppaca.idle = 0;
+ schedule();
+ if (cpu_is_offline(smp_processor_id()) &&
+ system_state == SYSTEM_RUNNING)
+ cpu_die();
+ }
+
+ return 0;
+}
+
+#endif /* CONFIG_PPC_PSERIES */
+
+static int native_idle(void)
+{
+ while(1) {
+ /* check CPU type here */
+ if (!need_resched())
+ power4_idle();
+ if (need_resched())
+ schedule();
+
+ if (cpu_is_offline(_smp_processor_id()) &&
+ system_state == SYSTEM_RUNNING)
+ cpu_die();
+ }
+ return 0;
+}
+
+#endif /* CONFIG_PPC_ISERIES */
+
+void cpu_idle(void)
+{
+ idle_loop();
+}
+
+int powersave_nap;
+
+#ifdef CONFIG_SYSCTL
+/*
+ * Register the sysctl to set/clear powersave_nap.
+ */
+static ctl_table powersave_nap_ctl_table[]={
+ {
+ .ctl_name = KERN_PPC_POWERSAVE_NAP,
+ .procname = "powersave-nap",
+ .data = &powersave_nap,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+ { 0, },
+};
+static ctl_table powersave_nap_sysctl_root[] = {
+ { 1, "kernel", NULL, 0, 0755, powersave_nap_ctl_table, },
+ { 0,},
+};
+
+static int __init
+register_powersave_nap_sysctl(void)
+{
+ register_sysctl_table(powersave_nap_sysctl_root, 0);
+
+ return 0;
+}
+__initcall(register_powersave_nap_sysctl);
+#endif
+
+int idle_setup(void)
+{
+ /*
+ * Move that junk to each platform specific file, eventually define
+ * a pSeries_idle for shared processor stuff
+ */
+#ifdef CONFIG_PPC_ISERIES
+ idle_loop = iSeries_idle;
+ return 1;
+#else
+ idle_loop = default_idle;
+#endif
+#ifdef CONFIG_PPC_PSERIES
+ if (systemcfg->platform & PLATFORM_PSERIES) {
+ if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR) {
+ if (get_paca()->lppaca.shared_proc) {
+ printk(KERN_INFO "Using shared processor idle loop\n");
+ idle_loop = shared_idle;
+ } else {
+ printk(KERN_INFO "Using dedicated idle loop\n");
+ idle_loop = dedicated_idle;
+ }
+ } else {
+ printk(KERN_INFO "Using default idle loop\n");
+ idle_loop = default_idle;
+ }
+ }
+#endif /* CONFIG_PPC_PSERIES */
+#ifndef CONFIG_PPC_ISERIES
+ if (systemcfg->platform == PLATFORM_POWERMAC ||
+ systemcfg->platform == PLATFORM_MAPLE) {
+ printk(KERN_INFO "Using native/NAP idle loop\n");
+ idle_loop = native_idle;
+ }
+#endif /* CONFIG_PPC_ISERIES */
+
+ return 1;
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.