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/* hardirq.h: PA-RISC hard IRQ support.

 *

 * Copyright (C) 2001 Matthew Wilcox <matthew@wil.cx>

 *

 * The locking is really quite interesting.  There's a cpu-local

 * count of how many interrupts are being handled, and a global

 * lock.  An interrupt can only be serviced if the global lock

 * is free.  You can't be sure no more interrupts are being

 * serviced until you've acquired the lock and then checked

 * all the per-cpu interrupt counts are all zero.  It's a specialised

 * br_lock, and that's exactly how Sparc does it.  We don't because

 * it's more locking for us.  This way is lock-free in the interrupt path.

 */

#ifndef _PARISC_HARDIRQ_H

#define _PARISC_HARDIRQ_H

#include <linux/config.h>

#include <linux/threads.h>

typedef struct {

        unsigned long __softirq_pending; /* set_bit is used on this */

        unsigned int __local_irq_count;

        unsigned int __local_bh_count;

        unsigned int __syscall_count;

        struct task_struct * __ksoftirqd_task;

} ____cacheline_aligned irq_cpustat_t;

#include <linux/irq_cpustat.h>  /* Standard mappings for irq_cpustat_t above */

/*

 * Are we in an interrupt context? Either doing bottom half

 * or hardware interrupt processing?

 */

#define in_interrupt() ({ int __cpu = smp_processor_id(); \

        (local_irq_count(__cpu) + local_bh_count(__cpu) != 0); })

#define in_irq() ({ int __cpu = smp_processor_id(); \

        (local_irq_count(__cpu) != 0); })

#ifndef CONFIG_SMP

#define hardirq_trylock(cpu)    (local_irq_count(cpu) == 0)

#define hardirq_endlock(cpu)    do { } while (0)

#define irq_enter(cpu, irq)     (local_irq_count(cpu)++)

#define irq_exit(cpu, irq)      (local_irq_count(cpu)--)

#define synchronize_irq()       barrier()

#else

#include <asm/system.h>

#include <asm/atomic.h>

#include <linux/spinlock.h>

#include <asm/smp.h>

extern int global_irq_holder;

extern spinlock_t global_irq_lock;

static inline int irqs_running (void)

{

        int i;

        for (i = 0; i < smp_num_cpus; i++)

                if (local_irq_count(i))

                        return 1;

        return 0;

}

static inline void release_irqlock(int cpu)

{

        /* if we didn't own the irq lock, just ignore.. */

        if (global_irq_holder == (unsigned char) cpu) {

                global_irq_holder = NO_PROC_ID;

                spin_unlock(&global_irq_lock);

        }

}

static inline void irq_enter(int cpu, int irq)

{

        ++local_irq_count(cpu);

        while (spin_is_locked(&global_irq_lock))

                barrier();

}

static inline void irq_exit(int cpu, int irq)

{

        --local_irq_count(cpu);

}

static inline int hardirq_trylock(int cpu)

{

        return !local_irq_count(cpu) && !spin_is_locked (&global_irq_lock);

}

#define hardirq_endlock(cpu)    do { } while (0)

extern void synchronize_irq(void);

#endif /* CONFIG_SMP */

#endif /* _PARISC_HARDIRQ_H */