1/* hardirq.h: PA-RISC hard IRQ support.
2 *
3 * Copyright (C) 2001 Matthew Wilcox <matthew@wil.cx>
4 *
5 * The locking is really quite interesting.  There's a cpu-local
6 * count of how many interrupts are being handled, and a global
7 * lock.  An interrupt can only be serviced if the global lock
8 * is free.  You can't be sure no more interrupts are being
9 * serviced until you've acquired the lock and then checked
10 * all the per-cpu interrupt counts are all zero.  It's a specialised
11 * br_lock, and that's exactly how Sparc does it.  We don't because
12 * it's more locking for us.  This way is lock-free in the interrupt path.
13 */
14
15#ifndef _PARISC_HARDIRQ_H
16#define _PARISC_HARDIRQ_H
17
18#include <linux/config.h>
19#include <linux/threads.h>
20
21typedef struct {
22	unsigned long __softirq_pending; /* set_bit is used on this */
23	unsigned int __local_irq_count;
24	unsigned int __local_bh_count;
25	unsigned int __syscall_count;
26	struct task_struct * __ksoftirqd_task;
27} ____cacheline_aligned irq_cpustat_t;
28
29#include <linux/irq_cpustat.h>	/* Standard mappings for irq_cpustat_t above */
30
31/*
32 * Are we in an interrupt context? Either doing bottom half
33 * or hardware interrupt processing?
34 */
35#define in_interrupt() ({ int __cpu = smp_processor_id(); \
36	(local_irq_count(__cpu) + local_bh_count(__cpu) != 0); })
37
38#define in_irq() ({ int __cpu = smp_processor_id(); \
39	(local_irq_count(__cpu) != 0); })
40
41#ifndef CONFIG_SMP
42
43#define hardirq_trylock(cpu)	(local_irq_count(cpu) == 0)
44#define hardirq_endlock(cpu)	do { } while (0)
45
46#define irq_enter(cpu, irq)	(local_irq_count(cpu)++)
47#define irq_exit(cpu, irq)	(local_irq_count(cpu)--)
48
49#define synchronize_irq()	barrier()
50
51#else
52
53#include <asm/system.h>
54#include <asm/atomic.h>
55#include <linux/spinlock.h>
56#include <asm/smp.h>
57
58extern int global_irq_holder;
59extern spinlock_t global_irq_lock;
60
61static inline int irqs_running (void)
62{
63	int i;
64
65	for (i = 0; i < smp_num_cpus; i++)
66		if (local_irq_count(i))
67			return 1;
68	return 0;
69}
70
71
72static inline void release_irqlock(int cpu)
73{
74	/* if we didn't own the irq lock, just ignore.. */
75	if (global_irq_holder == (unsigned char) cpu) {
76		global_irq_holder = NO_PROC_ID;
77		spin_unlock(&global_irq_lock);
78	}
79}
80
81static inline void irq_enter(int cpu, int irq)
82{
83	++local_irq_count(cpu);
84
85	while (spin_is_locked(&global_irq_lock))
86		barrier();
87}
88
89static inline void irq_exit(int cpu, int irq)
90{
91	--local_irq_count(cpu);
92}
93
94static inline int hardirq_trylock(int cpu)
95{
96	return !local_irq_count(cpu) && !spin_is_locked (&global_irq_lock);
97}
98
99#define hardirq_endlock(cpu)	do { } while (0)
100
101extern void synchronize_irq(void);
102
103#endif /* CONFIG_SMP */
104
105#endif /* _PARISC_HARDIRQ_H */
106