FreeBSD/Linux Kernel Cross Reference
sys/kernel/cpu_pm.c

     /*
      * Copyright (C) 2011 Google, Inc.
      *
      * Author:
      *      Colin Cross <ccross@android.com>
      *
      * This software is licensed under the terms of the GNU General Public
      * License version 2, as published by the Free Software Foundation, and
      * may be copied, distributed, and modified under those terms.
     *
     * This program is distributed in the hope that it will be useful,
     * but WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     * GNU General Public License for more details.
     *
     */
    
    #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>
    
    static DEFINE_RWLOCK(cpu_pm_notifier_lock);
    static RAW_NOTIFIER_HEAD(cpu_pm_notifier_chain);
    
    static int cpu_pm_notify(enum cpu_pm_event event, int nr_to_call, int *nr_calls)
    {
            int ret;
    
            ret = __raw_notifier_call_chain(&cpu_pm_notifier_chain, event, NULL,
                    nr_to_call, nr_calls);
    
            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 may sleep, and has the same return conditions as
     * raw_notifier_chain_register.
     */
    int cpu_pm_register_notifier(struct notifier_block *nb)
    {
            unsigned long flags;
            int ret;
    
            write_lock_irqsave(&cpu_pm_notifier_lock, flags);
            ret = raw_notifier_chain_register(&cpu_pm_notifier_chain, nb);
            write_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 may sleep, and has the same return conditions as
     * raw_notifier_chain_unregister.
     */
    int cpu_pm_unregister_notifier(struct notifier_block *nb)
    {
            unsigned long flags;
            int ret;
    
            write_lock_irqsave(&cpu_pm_notifier_lock, flags);
            ret = raw_notifier_chain_unregister(&cpu_pm_notifier_chain, nb);
            write_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)
    {
           int nr_calls;
           int ret = 0;
   
           read_lock(&cpu_pm_notifier_lock);
           ret = cpu_pm_notify(CPU_PM_ENTER, -1, &nr_calls);
           if (ret)
                   /*
                    * Inform listeners (nr_calls - 1) about failure of CPU PM
                    * PM entry who are notified earlier to prepare for it.
                    */
                   cpu_pm_notify(CPU_PM_ENTER_FAILED, nr_calls - 1, NULL);
           read_unlock(&cpu_pm_notifier_lock);
   
           return ret;
   }
   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)
   {
           int ret;
   
           read_lock(&cpu_pm_notifier_lock);
           ret = cpu_pm_notify(CPU_PM_EXIT, -1, NULL);
           read_unlock(&cpu_pm_notifier_lock);
   
           return ret;
   }
   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)
   {
           int nr_calls;
           int ret = 0;
   
           read_lock(&cpu_pm_notifier_lock);
           ret = cpu_pm_notify(CPU_CLUSTER_PM_ENTER, -1, &nr_calls);
           if (ret)
                   /*
                    * Inform listeners (nr_calls - 1) about failure of CPU cluster
                    * PM entry who are notified earlier to prepare for it.
                    */
                   cpu_pm_notify(CPU_CLUSTER_PM_ENTER_FAILED, nr_calls - 1, NULL);
           read_unlock(&cpu_pm_notifier_lock);
   
           return ret;
   }
   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_pm_exit 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.
    *
    * Return conditions are same as __raw_notifier_call_chain.
    */
   int cpu_cluster_pm_exit(void)
   {
           int ret;
   
           read_lock(&cpu_pm_notifier_lock);
           ret = cpu_pm_notify(CPU_CLUSTER_PM_EXIT, -1, NULL);
           read_unlock(&cpu_pm_notifier_lock);
   
           return ret;
   }
   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

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