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+/*
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+ * Copyright (C) 2011 Google, Inc.
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+ *
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+ * Author:
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+ * Colin Cross <ccross@android.com>
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+ *
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+ * This software is licensed under the terms of the GNU General Public
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+ * License version 2, as published by the Free Software Foundation, and
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+ * may be copied, distributed, and modified under those terms.
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+ *
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+ * This program is distributed in the hope that it will be useful,
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+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ * GNU General Public License for more details.
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+ *
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+ */
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+
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+#include <linux/kernel.h>
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+#include <linux/cpu_pm.h>
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+#include <linux/module.h>
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+#include <linux/notifier.h>
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+#include <linux/spinlock.h>
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+#include <linux/syscore_ops.h>
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+
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+static DEFINE_RWLOCK(cpu_pm_notifier_lock);
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+static RAW_NOTIFIER_HEAD(cpu_pm_notifier_chain);
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+
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+static int cpu_pm_notify(enum cpu_pm_event event, int nr_to_call, int *nr_calls)
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+{
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+ int ret;
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+
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+ ret = __raw_notifier_call_chain(&cpu_pm_notifier_chain, event, NULL,
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+ nr_to_call, nr_calls);
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+
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+ return notifier_to_errno(ret);
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+}
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+
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+/**
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+ * cpu_pm_register_notifier - register a driver with cpu_pm
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+ * @nb: notifier block to register
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+ *
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+ * Add a driver to a list of drivers that are notified about
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+ * CPU and CPU cluster low power entry and exit.
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+ *
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+ * This function may sleep, and has the same return conditions as
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+ * raw_notifier_chain_register.
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+ */
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+int cpu_pm_register_notifier(struct notifier_block *nb)
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+{
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+ unsigned long flags;
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+ int ret;
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+
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+ write_lock_irqsave(&cpu_pm_notifier_lock, flags);
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+ ret = raw_notifier_chain_register(&cpu_pm_notifier_chain, nb);
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+ write_unlock_irqrestore(&cpu_pm_notifier_lock, flags);
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+
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+ return ret;
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+}
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+EXPORT_SYMBOL_GPL(cpu_pm_register_notifier);
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+
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+/**
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+ * cpu_pm_unregister_notifier - unregister a driver with cpu_pm
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+ * @nb: notifier block to be unregistered
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+ *
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+ * Remove a driver from the CPU PM notifier list.
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+ *
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+ * This function may sleep, and has the same return conditions as
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+ * raw_notifier_chain_unregister.
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+ */
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+int cpu_pm_unregister_notifier(struct notifier_block *nb)
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+{
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+ unsigned long flags;
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+ int ret;
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+
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+ write_lock_irqsave(&cpu_pm_notifier_lock, flags);
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+ ret = raw_notifier_chain_unregister(&cpu_pm_notifier_chain, nb);
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+ write_unlock_irqrestore(&cpu_pm_notifier_lock, flags);
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+
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+ return ret;
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+}
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+EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier);
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+
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+/**
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+ * cpm_pm_enter - CPU low power entry notifier
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+ *
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+ * Notifies listeners that a single CPU is entering a low power state that may
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+ * cause some blocks in the same power domain as the cpu to reset.
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+ *
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+ * Must be called on the affected CPU with interrupts disabled. Platform is
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+ * responsible for ensuring that cpu_pm_enter is not called twice on the same
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+ * CPU before cpu_pm_exit is called. Notified drivers can include VFP
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+ * co-processor, interrupt controller and it's PM extensions, local CPU
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+ * timers context save/restore which shouldn't be interrupted. Hence it
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+ * must be called with interrupts disabled.
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+ *
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+ * Return conditions are same as __raw_notifier_call_chain.
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+ */
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+int cpu_pm_enter(void)
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+{
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+ int nr_calls;
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+ int ret = 0;
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+
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+ read_lock(&cpu_pm_notifier_lock);
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+ ret = cpu_pm_notify(CPU_PM_ENTER, -1, &nr_calls);
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+ if (ret)
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+ /*
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+ * Inform listeners (nr_calls - 1) about failure of CPU PM
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+ * PM entry who are notified earlier to prepare for it.
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+ */
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+ cpu_pm_notify(CPU_PM_ENTER_FAILED, nr_calls - 1, NULL);
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+ read_unlock(&cpu_pm_notifier_lock);
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+
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+ return ret;
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+}
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+EXPORT_SYMBOL_GPL(cpu_pm_enter);
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+
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+/**
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+ * cpm_pm_exit - CPU low power exit notifier
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+ *
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+ * Notifies listeners that a single CPU is exiting a low power state that may
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+ * have caused some blocks in the same power domain as the cpu to reset.
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+ *
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+ * Notified drivers can include VFP co-processor, interrupt controller
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+ * and it's PM extensions, local CPU timers context save/restore which
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+ * shouldn't be interrupted. Hence it must be called with interrupts disabled.
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+ *
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+ * Return conditions are same as __raw_notifier_call_chain.
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+ */
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+int cpu_pm_exit(void)
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+{
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+ int ret;
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+
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+ read_lock(&cpu_pm_notifier_lock);
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+ ret = cpu_pm_notify(CPU_PM_EXIT, -1, NULL);
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+ read_unlock(&cpu_pm_notifier_lock);
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+
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+ return ret;
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+}
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+EXPORT_SYMBOL_GPL(cpu_pm_exit);
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+
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+/**
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+ * cpm_cluster_pm_enter - CPU cluster low power entry notifier
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+ *
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+ * Notifies listeners that all cpus in a power domain are entering a low power
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+ * state that may cause some blocks in the same power domain to reset.
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+ *
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+ * Must be called after cpu_pm_enter has been called on all cpus in the power
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+ * domain, and before cpu_pm_exit has been called on any cpu in the power
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+ * domain. Notified drivers can include VFP co-processor, interrupt controller
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+ * and it's PM extensions, local CPU timers context save/restore which
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+ * shouldn't be interrupted. Hence it must be called with interrupts disabled.
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+ *
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+ * Must be called with interrupts disabled.
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+ *
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+ * Return conditions are same as __raw_notifier_call_chain.
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+ */
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+int cpu_cluster_pm_enter(void)
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+{
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+ int nr_calls;
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+ int ret = 0;
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+
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+ read_lock(&cpu_pm_notifier_lock);
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+ ret = cpu_pm_notify(CPU_CLUSTER_PM_ENTER, -1, &nr_calls);
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+ if (ret)
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+ /*
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+ * Inform listeners (nr_calls - 1) about failure of CPU cluster
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+ * PM entry who are notified earlier to prepare for it.
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+ */
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+ cpu_pm_notify(CPU_CLUSTER_PM_ENTER_FAILED, nr_calls - 1, NULL);
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+ read_unlock(&cpu_pm_notifier_lock);
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+
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+ return ret;
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+}
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+EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter);
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+
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+/**
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+ * cpm_cluster_pm_exit - CPU cluster low power exit notifier
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+ *
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+ * Notifies listeners that all cpus in a power domain are exiting form a
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+ * low power state that may have caused some blocks in the same power domain
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+ * to reset.
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+ *
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+ * Must be called after cpu_pm_exit has been called on all cpus in the power
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+ * domain, and before cpu_pm_exit has been called on any cpu in the power
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+ * domain. Notified drivers can include VFP co-processor, interrupt controller
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+ * and it's PM extensions, local CPU timers context save/restore which
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+ * shouldn't be interrupted. Hence it must be called with interrupts disabled.
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+ *
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+ * Return conditions are same as __raw_notifier_call_chain.
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+ */
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+int cpu_cluster_pm_exit(void)
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+{
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+ int ret;
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+
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+ read_lock(&cpu_pm_notifier_lock);
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+ ret = cpu_pm_notify(CPU_CLUSTER_PM_EXIT, -1, NULL);
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+ read_unlock(&cpu_pm_notifier_lock);
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+
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+ return ret;
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+}
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+EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);
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+
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+#ifdef CONFIG_PM
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+static int cpu_pm_suspend(void)
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+{
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+ int ret;
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+
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+ ret = cpu_pm_enter();
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+ if (ret)
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+ return ret;
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+
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+ ret = cpu_cluster_pm_enter();
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+ return ret;
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+}
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+
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+static void cpu_pm_resume(void)
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+{
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+ cpu_cluster_pm_exit();
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+ cpu_pm_exit();
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+}
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+
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+static struct syscore_ops cpu_pm_syscore_ops = {
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+ .suspend = cpu_pm_suspend,
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+ .resume = cpu_pm_resume,
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+};
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+
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+static int cpu_pm_init(void)
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+{
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+ register_syscore_ops(&cpu_pm_syscore_ops);
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+ return 0;
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+}
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+core_initcall(cpu_pm_init);
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+#endif
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Russell King