Linux Cross Reference
Linux/include/linux/interrupt.h

   /* interrupt.h */
   #ifndef _LINUX_INTERRUPT_H
   #define _LINUX_INTERRUPT_H
   
   #include <linux/config.h>
   #include <linux/kernel.h>
   #include <linux/smp.h>
   #include <linux/cache.h>
   
  #include <asm/bitops.h>
  #include <asm/atomic.h>
  #include <asm/ptrace.h>
  
  struct irqaction {
          void (*handler)(int, void *, struct pt_regs *);
          unsigned long flags;
          unsigned long mask;
          const char *name;
          void *dev_id;
          struct irqaction *next;
  };
  
  
  /* Who gets which entry in bh_base.  Things which will occur most often
     should come first */
     
  enum {
          TIMER_BH = 0,
          TQUEUE_BH,
          DIGI_BH,
          SERIAL_BH,
          RISCOM8_BH,
          SPECIALIX_BH,
          AURORA_BH,
          ESP_BH,
          SCSI_BH,
          IMMEDIATE_BH,
          CYCLADES_BH,
          CM206_BH,
          JS_BH,
          MACSERIAL_BH,
          ISICOM_BH
  };
  
  #include <asm/hardirq.h>
  #include <asm/softirq.h>
  
  
  
  /* PLEASE, avoid to allocate new softirqs, if you need not _really_ high
     frequency threaded job scheduling. For almost all the purposes
     tasklets are more than enough. F.e. all serial device BHs et
     al. should be converted to tasklets, not to softirqs.
   */
  
  enum
  {
          HI_SOFTIRQ=0,
          NET_TX_SOFTIRQ,
          NET_RX_SOFTIRQ,
          TASKLET_SOFTIRQ
  };
  
  /* softirq mask and active fields moved to irq_cpustat_t in
   * asm/hardirq.h to get better cache usage.  KAO
   */
  
  struct softirq_action
  {
          void    (*action)(struct softirq_action *);
          void    *data;
  };
  
  asmlinkage void do_softirq(void);
  extern void open_softirq(int nr, void (*action)(struct softirq_action*), void *data);
  
  static inline void __cpu_raise_softirq(int cpu, int nr)
  {
          softirq_active(cpu) |= (1<<nr);
  }
  
  
  /* I do not want to use atomic variables now, so that cli/sti */
  static inline void raise_softirq(int nr)
  {
          unsigned long flags;
  
          local_irq_save(flags);
          __cpu_raise_softirq(smp_processor_id(), nr);
          local_irq_restore(flags);
  }
  
  extern void softirq_init(void);
  
  
  
  /* Tasklets --- multithreaded analogue of BHs.
  
     Main feature differing them of generic softirqs: tasklet
    is running only on one CPU simultaneously.
 
    Main feature differing them of BHs: different tasklets
    may be run simultaneously on different CPUs.
 
    Properties:
    * If tasklet_schedule() is called, then tasklet is guaranteed
      to be executed on some cpu at least once after this.
    * If the tasklet is already scheduled, but its excecution is still not
      started, it will be executed only once.
    * If this tasklet is already running on another CPU (or schedule is called
      from tasklet itself), it is rescheduled for later.
    * Tasklet is strictly serialized wrt itself, but not
      wrt another tasklets. If client needs some intertask synchronization,
      he makes it with spinlocks.
  */
 
 struct tasklet_struct
 {
         struct tasklet_struct *next;
         unsigned long state;
         atomic_t count;
         void (*func)(unsigned long);
         unsigned long data;
 };
 
 #define DECLARE_TASKLET(name, func, data) \
 struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(0), func, data }
 
 #define DECLARE_TASKLET_DISABLED(name, func, data) \
 struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(1), func, data }
 
 
 enum
 {
         TASKLET_STATE_SCHED,    /* Tasklet is scheduled for execution */
         TASKLET_STATE_RUN       /* Tasklet is running (SMP only) */
 };
 
 struct tasklet_head
 {
         struct tasklet_struct *list;
 } __attribute__ ((__aligned__(SMP_CACHE_BYTES)));
 
 extern struct tasklet_head tasklet_vec[NR_CPUS];
 extern struct tasklet_head tasklet_hi_vec[NR_CPUS];
 
 #ifdef CONFIG_SMP
 #define tasklet_trylock(t) (!test_and_set_bit(TASKLET_STATE_RUN, &(t)->state))
 #define tasklet_unlock_wait(t) while (test_bit(TASKLET_STATE_RUN, &(t)->state)) { /* NOTHING */ }
 #define tasklet_unlock(t) clear_bit(TASKLET_STATE_RUN, &(t)->state)
 #else
 #define tasklet_trylock(t) 1
 #define tasklet_unlock_wait(t) do { } while (0)
 #define tasklet_unlock(t) do { } while (0)
 #endif
 
 static inline void tasklet_schedule(struct tasklet_struct *t)
 {
         if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
                 int cpu = smp_processor_id();
                 unsigned long flags;
 
                 local_irq_save(flags);
                 t->next = tasklet_vec[cpu].list;
                 tasklet_vec[cpu].list = t;
                 __cpu_raise_softirq(cpu, TASKLET_SOFTIRQ);
                 local_irq_restore(flags);
         }
 }
 
 static inline void tasklet_hi_schedule(struct tasklet_struct *t)
 {
         if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
                 int cpu = smp_processor_id();
                 unsigned long flags;
 
                 local_irq_save(flags);
                 t->next = tasklet_hi_vec[cpu].list;
                 tasklet_hi_vec[cpu].list = t;
                 __cpu_raise_softirq(cpu, HI_SOFTIRQ);
                 local_irq_restore(flags);
         }
 }
 
 
 static inline void tasklet_disable_nosync(struct tasklet_struct *t)
 {
         atomic_inc(&t->count);
 }
 
 static inline void tasklet_disable(struct tasklet_struct *t)
 {
         tasklet_disable_nosync(t);
         tasklet_unlock_wait(t);
 }
 
 static inline void tasklet_enable(struct tasklet_struct *t)
 {
         atomic_dec(&t->count);
 }
 
 extern void tasklet_kill(struct tasklet_struct *t);
 extern void tasklet_init(struct tasklet_struct *t,
                          void (*func)(unsigned long), unsigned long data);
 
 #ifdef CONFIG_SMP
 
 #define SMP_TIMER_NAME(name) name##__thr
 
 #define SMP_TIMER_DEFINE(name, task) \
 DECLARE_TASKLET(task, name##__thr, 0); \
 static void name (unsigned long dummy) \
 { \
         tasklet_schedule(&(task)); \
 }
 
 #else /* CONFIG_SMP */
 
 #define SMP_TIMER_NAME(name) name
 #define SMP_TIMER_DEFINE(name, task)
 
 #endif /* CONFIG_SMP */
 
 
 /* Old BH definitions */
 
 extern struct tasklet_struct bh_task_vec[];
 
 /* It is exported _ONLY_ for wait_on_irq(). */
 extern spinlock_t global_bh_lock;
 
 static inline void mark_bh(int nr)
 {
         tasklet_hi_schedule(bh_task_vec+nr);
 }
 
 extern void init_bh(int nr, void (*routine)(void));
 extern void remove_bh(int nr);
 
 
 /*
  * Autoprobing for irqs:
  *
  * probe_irq_on() and probe_irq_off() provide robust primitives
  * for accurate IRQ probing during kernel initialization.  They are
  * reasonably simple to use, are not "fooled" by spurious interrupts,
  * and, unlike other attempts at IRQ probing, they do not get hung on
  * stuck interrupts (such as unused PS2 mouse interfaces on ASUS boards).
  *
  * For reasonably foolproof probing, use them as follows:
  *
  * 1. clear and/or mask the device's internal interrupt.
  * 2. sti();
  * 3. irqs = probe_irq_on();      // "take over" all unassigned idle IRQs
  * 4. enable the device and cause it to trigger an interrupt.
  * 5. wait for the device to interrupt, using non-intrusive polling or a delay.
  * 6. irq = probe_irq_off(irqs);  // get IRQ number, 0=none, negative=multiple
  * 7. service the device to clear its pending interrupt.
  * 8. loop again if paranoia is required.
  *
  * probe_irq_on() returns a mask of allocated irq's.
  *
  * probe_irq_off() takes the mask as a parameter,
  * and returns the irq number which occurred,
  * or zero if none occurred, or a negative irq number
  * if more than one irq occurred.
  */
 extern unsigned long probe_irq_on(void);        /* returns 0 on failure */
 extern int probe_irq_off(unsigned long);        /* returns 0 or negative on failure */
 extern unsigned int probe_irq_mask(unsigned long);      /* returns mask of ISA interrupts */
 
 #endif