kernel syscore

syscore作为低功耗流程的一部分，其涉及的文件主要有syscore_ops.h和syscore.c，这一级别的回调函数是在完全屏蔽中断的场景下进行的。

1、主要结构体struct syscore_ops，该结构体是syscore操作的对象类型。

   
    

     
 
      
 
       
 
      
 
      
 
       
 
        struct 
        syscore_ops { 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        struct 
        list_head node; 
        //用于链表控制，注册和删除syscore对象时操作此链表完成 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        int (*suspend)( 
        void); 
        //睡眠流程时回调函数 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        void (*resume)( 
        void); 
        //唤醒流程时回调函数 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        void (*shutdown)( 
        void); 
        //这一级别的回调函数主要用于系统级的重启、停止或者掉电时才会使用 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         }; 
       
 
      
    
   
    

2、主要接口：

   
    

     
 
      
 
       
 
      
 
      
 
       
 
        extern void register_syscore_ops(struct syscore_ops *ops); 
        //注册syscore回调函数 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        extern void unregister_syscore_ops(struct syscore_ops *ops); 
        //取消注册的回调函数 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        #ifdef CONFIG_PM_SLEEP 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        extern int syscore_suspend(void); 
        //回调注册的syscore对象的suspend回调函数 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        extern void syscore_resume(void); 
        //回调注册的syscore对象的resume回调函数 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        #endif 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        extern void syscore_shutdown(void); 
        //回调注册的syscore对象的shutdown回调函数 
       
 
      
    
   
    

3、具体实现，syscore.c

1)全局变量

   
    

     
 
      
 
       
 
      
 
      
 
       
 
        static LIST_HEAD(syscore_ops_list); 
        //初始化控制链表头结点，统一管理注册的syscore对象 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        static DEFINE_MUTEX(syscore_ops_lock); 
        //访问上述链表时，通过此互斥信号量来互斥访问 
       
 
      
    
   
    

2)register_syscore_ops：其他组件主要通过此接口来注册回调函数，我们可以看到，把注册的对象存放在了syscore_ops_list链表中。

   
    

     
 
      
 
       
 
      
 
      
 
       
 
        /** 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         * register_syscore_ops - Register a set of system core operations. 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         * @ops: System core operations to register. 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         */ 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        void register_syscore_ops(struct syscore_ops *ops) 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         { 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        mutex_lock(&syscore_ops_lock); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        list_add_tail(&ops->node, &syscore_ops_list); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        mutex_unlock(&syscore_ops_lock); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         } 
       
 
      
    
   
    

3)unregister_syscore_ops:与register_syscore_ops功能相反，取消注册，从控制链表中删除。

   
    

     
 
      
 
       
 
      
 
      
 
       
 
        /** 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         * unregister_syscore_ops - Unregister a set of system core operations. 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         * @ops: System core operations to unregister. 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         */ 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        void unregister_syscore_ops(struct syscore_ops *ops) 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         { 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        mutex_lock(&syscore_ops_lock); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        list_del(&ops->node); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        mutex_unlock(&syscore_ops_lock); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         } 
       
 
      
    
   
    

4)syscore_suspend:该接口回调所有注册对象的suspend接口，该接口在suspend.c的suspend_enter函数中被调用，执行cpu掉电前的最后阶段操作。

   
    

     
 
      
 
       
 
      
 
      
 
       
 
        /** 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         * syscore_suspend - Execute all the registered system core suspend callbacks. 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         * 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         * This function is executed with one CPU on-line and disabled interrupts. 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         */ 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        int syscore_suspend(void) 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         { 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        struct 
        syscore_ops *ops; 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        int ret = 
        0; 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        pr_debug( 
        "Checking wakeup interrupts\n"); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        /* Return error code if there are any wakeup interrupts pending. */ 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         ret = 
        check_wakeup_irqs(); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        if (ret) 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        return ret; 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        WARN_ONCE(! 
        irqs_disabled(), 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        "Interrupts enabled before system core suspend.\n"); 
        //我们可以看到，如果此时中断没有屏蔽掉，会有警告产生 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        list_for_each_entry_reverse(ops, &syscore_ops_list, node) 
        //按照链表逆序执行各个注册对象的suspend回调函数 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        if (ops->suspend) { 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        if (initcall_debug) 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        pr_info( 
        "PM: Calling %pF\n", ops->suspend); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         ret = ops-> 
        suspend(); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        if (ret) 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        goto err_out; 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        WARN_ONCE(! 
        irqs_disabled(), 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        "Interrupts enabled after %pF\n", ops->suspend); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         } 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        return 
        0; 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         err_out: 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        pr_err( 
        "PM: System core suspend callback %pF failed.\n", ops->suspend); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        list_for_each_entry_continue(ops, &syscore_ops_list, node) 
        //如果有失败的，则执行已经执行过suspend回调的对象的resume回调 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        if (ops->resume) 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         ops-> 
        resume(); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        return ret; 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         } 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        EXPORT_SYMBOL_GPL(syscore_suspend); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
    
   
    

    
     
   
    
   
    

5)syscore_resume:执行注册对象的resume回调，在suspend.c的唤醒流程中被调用

   
    

     
 
      
 
       
 
      
 
      
 
       
 
        /** 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         * syscore_resume - Execute all the registered system core resume callbacks. 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         * 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         * This function is executed with one CPU on-line and disabled interrupts. 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         */ 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        void syscore_resume(void) 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         { 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        struct 
        syscore_ops *ops; 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        WARN_ONCE(! 
        irqs_disabled(), 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        "Interrupts enabled before system core resume.\n"); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        list_for_each_entry(ops, &syscore_ops_list, node) 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        if (ops->resume) { 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        if (initcall_debug) 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        pr_info( 
        "PM: Calling %pF\n", ops->resume); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         ops-> 
        resume(); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        WARN_ONCE(! 
        irqs_disabled(), 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        "Interrupts enabled after %pF\n", ops->resume); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         } 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         } 
       
 
      
    
   
    

    
     
   
    
   
    

6)syscore_shutdown:该接口正常睡眠流程中不涉及调用，主要在sys.c中调用，涉及系统重启、halt等流程。

   
    

     
 
      
 
       
 
      
 
      
 
       
 
        /** 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         * syscore_shutdown - Execute all the registered system core shutdown callbacks. 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
         */ 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        void syscore_shutdown(void) 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         { 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        struct 
        syscore_ops *ops; 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        mutex_lock(&syscore_ops_lock); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        list_for_each_entry_reverse(ops, &syscore_ops_list, node) 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        if (ops->shutdown) { 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        if (initcall_debug) 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        pr_info( 
        "PM: Calling %pF\n", ops->shutdown); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         ops-> 
        shutdown(); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         } 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
       
 
      
     
 
      
 
       
 
      
 
      
 
       
 
        mutex_unlock(&syscore_ops_lock); 
       
 
      
     
 
      
 
       
 
      
 
      
 
       

         }