include/linux/interrupt.h

/* interrupt.h */
#ifndef _LINUX_INTERRUPT_H
#define _LINUX_INTERRUPT_H

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/linkage.h>
#include <linux/bitops.h>
#include <linux/preempt.h>
#include <linux/cpumask.h>
#include <linux/hardirq.h>
#include <asm/atomic.h>
#include <asm/ptrace.h>
#include <asm/system.h>

/*
 * For 2.4.x compatibility, 2.4.x can use
 *
 *	typedef void irqreturn_t;
 *	#define IRQ_NONE
 *	#define IRQ_HANDLED
 *	#define IRQ_RETVAL(x)
 *
 * To mix old-style and new-style irq handler returns.
 *
 * IRQ_NONE means we didn't handle it.
 * IRQ_HANDLED means that we did have a valid interrupt and handled it.
 * IRQ_RETVAL(x) selects on the two depending on x being non-zero (for handled)
 */
typedef int irqreturn_t;

#define IRQ_NONE	(0)
#define IRQ_HANDLED	(1)
#define IRQ_RETVAL(x)	((x) != 0)

struct irqaction {
	irqreturn_t (*handler)(int, void *, struct pt_regs *);
	unsigned long flags;
	cpumask_t mask;
	const char *name;
	void *dev_id;
	struct irqaction *next;
	int irq;
	struct proc_dir_entry *dir;
};

extern irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs);
extern int request_irq(unsigned int,
		       irqreturn_t (*handler)(int, void *, struct pt_regs *),
		       unsigned long, const char *, void *);
extern void free_irq(unsigned int, void *);


#ifdef CONFIG_GENERIC_HARDIRQS
extern void disable_irq_nosync(unsigned int irq);
extern void disable_irq(unsigned int irq);
extern void enable_irq(unsigned int irq);
#endif

/*
 * Temporary defines for UP kernels, until all code gets fixed.
 */
#ifndef CONFIG_SMP
static inline void __deprecated cli(void)
{
	local_irq_disable();
}
static inline void __deprecated sti(void)
{
	local_irq_enable();
}
static inline void __deprecated save_flags(unsigned long *x)
{
	local_save_flags(*x);
}
#define save_flags(x) save_flags(&x);
static inline void __deprecated restore_flags(unsigned long x)
{
	local_irq_restore(x);
}

static inline void __deprecated save_and_cli(unsigned long *x)
{
	local_irq_save(*x);
}
#define save_and_cli(x)	save_and_cli(&x)
#endif /* CONFIG_SMP */

/* SoftIRQ primitives.  */
#define local_bh_disable() \
		do { add_preempt_count(SOFTIRQ_OFFSET); barrier(); } while (0)
#define __local_bh_enable() \
		do { barrier(); sub_preempt_count(SOFTIRQ_OFFSET); } while (0)

extern void local_bh_enable(void);

/* 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,
	TIMER_SOFTIRQ,
	NET_TX_SOFTIRQ,
	NET_RX_SOFTIRQ,
	SCSI_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);
extern void softirq_init(void);
#define __raise_softirq_irqoff(nr) do { local_softirq_pending() |= 1UL << (nr); } while (0)
extern void FASTCALL(raise_softirq_irqoff(unsigned int nr));
extern void FASTCALL(raise_softirq(unsigned int nr));


/* 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) */
};

#ifdef CONFIG_SMP
static inline int tasklet_trylock(struct tasklet_struct *t)
{
	return !test_and_set_bit(TASKLET_STATE_RUN, &(t)->state);
}

static inline void tasklet_unlock(struct tasklet_struct *t)
{
	smp_mb__before_clear_bit(); 
	clear_bit(TASKLET_STATE_RUN, &(t)->state);
}

static inline void tasklet_unlock_wait(struct tasklet_struct *t)
{
	while (test_bit(TASKLET_STATE_RUN, &(t)->state)) { barrier(); }
}
#else
#define tasklet_trylock(t) 1
#define tasklet_unlock_wait(t) do { } while (0)
#define tasklet_unlock(t) do { } while (0)
#endif

extern void FASTCALL(__tasklet_schedule(struct tasklet_struct *t));

static inline void tasklet_schedule(struct tasklet_struct *t)
{
	if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
		__tasklet_schedule(t);
}

extern void FASTCALL(__tasklet_hi_schedule(struct tasklet_struct *t));

static inline void tasklet_hi_schedule(struct tasklet_struct *t)
{
	if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
		__tasklet_hi_schedule(t);
}


static inline void tasklet_disable_nosync(struct tasklet_struct *t)
{
	atomic_inc(&t->count);
	smp_mb__after_atomic_inc();
}

static inline void tasklet_disable(struct tasklet_struct *t)
{
	tasklet_disable_nosync(t);
	tasklet_unlock_wait(t);
	smp_mb();
}

static inline void tasklet_enable(struct tasklet_struct *t)
{
	smp_mb__before_atomic_dec();
	atomic_dec(&t->count);
}

static inline void tasklet_hi_enable(struct tasklet_struct *t)
{
	smp_mb__before_atomic_dec();
	atomic_dec(&t->count);
}

extern void tasklet_kill(struct tasklet_struct *t);
extern void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu);
extern void tasklet_init(struct tasklet_struct *t,
			 void (*func)(unsigned long), unsigned long data);

/*
 * 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.
 */

#if defined(CONFIG_GENERIC_HARDIRQS) && !defined(CONFIG_GENERIC_IRQ_PROBE) 
static inline unsigned long probe_irq_on(void)
{
	return 0;
}
static inline int probe_irq_off(unsigned long val)
{
	return 0;
}
static inline unsigned int probe_irq_mask(unsigned long val)
{
	return 0;
}
#else
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

#endif