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-rw-r--r--kernel/cpu_pm.c214
1 files changed, 214 insertions, 0 deletions
diff --git a/kernel/cpu_pm.c b/kernel/cpu_pm.c
new file mode 100644
index 000000000..246efc74e
--- /dev/null
+++ b/kernel/cpu_pm.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * Author:
+ * Colin Cross <ccross@android.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/cpu_pm.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/spinlock.h>
+#include <linux/syscore_ops.h>
+
+/*
+ * atomic_notifiers use a spinlock_t, which can block under PREEMPT_RT.
+ * Notifications for cpu_pm will be issued by the idle task itself, which can
+ * never block, IOW it requires using a raw_spinlock_t.
+ */
+static struct {
+ struct raw_notifier_head chain;
+ raw_spinlock_t lock;
+} cpu_pm_notifier = {
+ .chain = RAW_NOTIFIER_INIT(cpu_pm_notifier.chain),
+ .lock = __RAW_SPIN_LOCK_UNLOCKED(cpu_pm_notifier.lock),
+};
+
+static int cpu_pm_notify(enum cpu_pm_event event)
+{
+ int ret;
+
+ /*
+ * This introduces a RCU read critical section, which could be
+ * disfunctional in cpu idle. Copy RCU_NONIDLE code to let RCU know
+ * this.
+ */
+ rcu_irq_enter_irqson();
+ rcu_read_lock();
+ ret = raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL);
+ rcu_read_unlock();
+ rcu_irq_exit_irqson();
+
+ return notifier_to_errno(ret);
+}
+
+static int cpu_pm_notify_robust(enum cpu_pm_event event_up, enum cpu_pm_event event_down)
+{
+ unsigned long flags;
+ int ret;
+
+ rcu_irq_enter_irqson();
+ raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
+ ret = raw_notifier_call_chain_robust(&cpu_pm_notifier.chain, event_up, event_down, NULL);
+ raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
+ rcu_irq_exit_irqson();
+
+ return notifier_to_errno(ret);
+}
+
+/**
+ * cpu_pm_register_notifier - register a driver with cpu_pm
+ * @nb: notifier block to register
+ *
+ * Add a driver to a list of drivers that are notified about
+ * CPU and CPU cluster low power entry and exit.
+ *
+ * This function has the same return conditions as raw_notifier_chain_register.
+ */
+int cpu_pm_register_notifier(struct notifier_block *nb)
+{
+ unsigned long flags;
+ int ret;
+
+ raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
+ ret = raw_notifier_chain_register(&cpu_pm_notifier.chain, nb);
+ raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(cpu_pm_register_notifier);
+
+/**
+ * cpu_pm_unregister_notifier - unregister a driver with cpu_pm
+ * @nb: notifier block to be unregistered
+ *
+ * Remove a driver from the CPU PM notifier list.
+ *
+ * This function has the same return conditions as raw_notifier_chain_unregister.
+ */
+int cpu_pm_unregister_notifier(struct notifier_block *nb)
+{
+ unsigned long flags;
+ int ret;
+
+ raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
+ ret = raw_notifier_chain_unregister(&cpu_pm_notifier.chain, nb);
+ raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier);
+
+/**
+ * cpu_pm_enter - CPU low power entry notifier
+ *
+ * Notifies listeners that a single CPU is entering a low power state that may
+ * cause some blocks in the same power domain as the cpu to reset.
+ *
+ * Must be called on the affected CPU with interrupts disabled. Platform is
+ * responsible for ensuring that cpu_pm_enter is not called twice on the same
+ * CPU before cpu_pm_exit is called. Notified drivers can include VFP
+ * co-processor, interrupt controller and its PM extensions, local CPU
+ * timers context save/restore which shouldn't be interrupted. Hence it
+ * must be called with interrupts disabled.
+ *
+ * Return conditions are same as __raw_notifier_call_chain.
+ */
+int cpu_pm_enter(void)
+{
+ return cpu_pm_notify_robust(CPU_PM_ENTER, CPU_PM_ENTER_FAILED);
+}
+EXPORT_SYMBOL_GPL(cpu_pm_enter);
+
+/**
+ * cpu_pm_exit - CPU low power exit notifier
+ *
+ * Notifies listeners that a single CPU is exiting a low power state that may
+ * have caused some blocks in the same power domain as the cpu to reset.
+ *
+ * Notified drivers can include VFP co-processor, interrupt controller
+ * and its PM extensions, local CPU timers context save/restore which
+ * shouldn't be interrupted. Hence it must be called with interrupts disabled.
+ *
+ * Return conditions are same as __raw_notifier_call_chain.
+ */
+int cpu_pm_exit(void)
+{
+ return cpu_pm_notify(CPU_PM_EXIT);
+}
+EXPORT_SYMBOL_GPL(cpu_pm_exit);
+
+/**
+ * cpu_cluster_pm_enter - CPU cluster low power entry notifier
+ *
+ * Notifies listeners that all cpus in a power domain are entering a low power
+ * state that may cause some blocks in the same power domain to reset.
+ *
+ * Must be called after cpu_pm_enter has been called on all cpus in the power
+ * domain, and before cpu_pm_exit has been called on any cpu in the power
+ * domain. Notified drivers can include VFP co-processor, interrupt controller
+ * and its PM extensions, local CPU timers context save/restore which
+ * shouldn't be interrupted. Hence it must be called with interrupts disabled.
+ *
+ * Must be called with interrupts disabled.
+ *
+ * Return conditions are same as __raw_notifier_call_chain.
+ */
+int cpu_cluster_pm_enter(void)
+{
+ return cpu_pm_notify_robust(CPU_CLUSTER_PM_ENTER, CPU_CLUSTER_PM_ENTER_FAILED);
+}
+EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter);
+
+/**
+ * cpu_cluster_pm_exit - CPU cluster low power exit notifier
+ *
+ * Notifies listeners that all cpus in a power domain are exiting form a
+ * low power state that may have caused some blocks in the same power domain
+ * to reset.
+ *
+ * Must be called after cpu_cluster_pm_enter has been called for the power
+ * domain, and before cpu_pm_exit has been called on any cpu in the power
+ * domain. Notified drivers can include VFP co-processor, interrupt controller
+ * and its PM extensions, local CPU timers context save/restore which
+ * shouldn't be interrupted. Hence it must be called with interrupts disabled.
+ *
+ * Return conditions are same as __raw_notifier_call_chain.
+ */
+int cpu_cluster_pm_exit(void)
+{
+ return cpu_pm_notify(CPU_CLUSTER_PM_EXIT);
+}
+EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);
+
+#ifdef CONFIG_PM
+static int cpu_pm_suspend(void)
+{
+ int ret;
+
+ ret = cpu_pm_enter();
+ if (ret)
+ return ret;
+
+ ret = cpu_cluster_pm_enter();
+ return ret;
+}
+
+static void cpu_pm_resume(void)
+{
+ cpu_cluster_pm_exit();
+ cpu_pm_exit();
+}
+
+static struct syscore_ops cpu_pm_syscore_ops = {
+ .suspend = cpu_pm_suspend,
+ .resume = cpu_pm_resume,
+};
+
+static int cpu_pm_init(void)
+{
+ register_syscore_ops(&cpu_pm_syscore_ops);
+ return 0;
+}
+core_initcall(cpu_pm_init);
+#endif