include/linux/interrupt.h

   1 /* interrupt.h */
   2 #ifndef _LINUX_INTERRUPT_H
   3 #define _LINUX_INTERRUPT_H
   4
   5 #include <linux/kernel.h>
   6 #include <linux/linkage.h>
   7 #include <linux/bitops.h>
   8 #include <linux/preempt.h>
   9 #include <linux/cpumask.h>
  10 #include <linux/irqreturn.h>
  11 #include <linux/irqnr.h>
  12 #include <linux/hardirq.h>
  13 #include <linux/irqflags.h>
  14 #include <linux/hrtimer.h>
  15 #include <linux/kref.h>
  16 #include <linux/workqueue.h>
  17
  18 #include <linux/atomic.h>
  19 #include <asm/ptrace.h>
  20 #include <asm/irq.h>
  21
  22 /*
  23  * These correspond to the IORESOURCE_IRQ_* defines in
  24  * linux/ioport.h to select the interrupt line behaviour.  When
  25  * requesting an interrupt without specifying a IRQF_TRIGGER, the
  26  * setting should be assumed to be "as already configured", which
  27  * may be as per machine or firmware initialisation.
  28  */
  29 #define IRQF_TRIGGER_NONE       0x00000000
  30 #define IRQF_TRIGGER_RISING     0x00000001
  31 #define IRQF_TRIGGER_FALLING    0x00000002
  32 #define IRQF_TRIGGER_HIGH       0x00000004
  33 #define IRQF_TRIGGER_LOW        0x00000008
  34 #define IRQF_TRIGGER_MASK       (IRQF_TRIGGER_HIGH | IRQF_TRIGGER_LOW | \
  35                                  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING)
  36 #define IRQF_TRIGGER_PROBE      0x00000010
  37
  38 /*
  39  * These flags used only by the kernel as part of the
  40  * irq handling routines.
  41  *
  42  * IRQF_SHARED - allow sharing the irq among several devices
  43  * IRQF_PROBE_SHARED - set by callers when they expect sharing mismatches to occur
  44  * IRQF_TIMER - Flag to mark this interrupt as timer interrupt
  45  * IRQF_PERCPU - Interrupt is per cpu
  46  * IRQF_NOBALANCING - Flag to exclude this interrupt from irq balancing
  47  * IRQF_IRQPOLL - Interrupt is used for polling (only the interrupt that is
  48  *                registered first in an shared interrupt is considered for
  49  *                performance reasons)
  50  * IRQF_ONESHOT - Interrupt is not reenabled after the hardirq handler finished.
  51  *                Used by threaded interrupts which need to keep the
  52  *                irq line disabled until the threaded handler has been run.
  53  * IRQF_NO_SUSPEND - Do not disable this IRQ during suspend.  Does not guarantee
  54  *                   that this interrupt will wake the system from a suspended
  55  *                   state.  See Documentation/power/suspend-and-interrupts.txt
  56  * IRQF_FORCE_RESUME - Force enable it on resume even if IRQF_NO_SUSPEND is set
  57  * IRQF_NO_THREAD - Interrupt cannot be threaded
  58  * IRQF_EARLY_RESUME - Resume IRQ early during syscore instead of at device
  59  *                resume time.
  60  * IRQF_COND_SUSPEND - If the IRQ is shared with a NO_SUSPEND user, execute this
  61  *                interrupt handler after suspending interrupts. For system
  62  *                wakeup devices users need to implement wakeup detection in
  63  *                their interrupt handlers.
  64  */
  65 #define IRQF_SHARED             0x00000080
  66 #define IRQF_PROBE_SHARED       0x00000100
  67 #define __IRQF_TIMER            0x00000200
  68 #define IRQF_PERCPU             0x00000400
  69 #define IRQF_NOBALANCING        0x00000800
  70 #define IRQF_IRQPOLL            0x00001000
  71 #define IRQF_ONESHOT            0x00002000
  72 #define IRQF_NO_SUSPEND         0x00004000
  73 #define IRQF_FORCE_RESUME       0x00008000
  74 #define IRQF_NO_THREAD          0x00010000
  75 #define IRQF_EARLY_RESUME       0x00020000
  76 #define IRQF_COND_SUSPEND       0x00040000
  77
  78 #define IRQF_TIMER              (__IRQF_TIMER | IRQF_NO_SUSPEND | IRQF_NO_THREAD)
  79
  80 /*
  81  * These values can be returned by request_any_context_irq() and
  82  * describe the context the interrupt will be run in.
  83  *
  84  * IRQC_IS_HARDIRQ - interrupt runs in hardirq context
  85  * IRQC_IS_NESTED - interrupt runs in a nested threaded context
  86  */
  87 enum {
  88         IRQC_IS_HARDIRQ = 0,
  89         IRQC_IS_NESTED,
  90 };
  91
  92 typedef irqreturn_t (*irq_handler_t)(int, void *);
  93
  94 /**
  95  * struct irqaction - per interrupt action descriptor
  96  * @handler:    interrupt handler function
  97  * @name:       name of the device
  98  * @dev_id:     cookie to identify the device
  99  * @percpu_dev_id:      cookie to identify the device
 100  * @next:       pointer to the next irqaction for shared interrupts
 101  * @irq:        interrupt number
 102  * @flags:      flags (see IRQF_* above)
 103  * @thread_fn:  interrupt handler function for threaded interrupts
 104  * @thread:     thread pointer for threaded interrupts
 105  * @secondary:  pointer to secondary irqaction (force threading)
 106  * @thread_flags:       flags related to @thread
 107  * @thread_mask:        bitmask for keeping track of @thread activity
 108  * @dir:        pointer to the proc/irq/NN/name entry
 109  */
 110 struct irqaction {
 111         irq_handler_t           handler;
 112         void                    *dev_id;
 113         void __percpu           *percpu_dev_id;
 114         struct irqaction        *next;
 115         irq_handler_t           thread_fn;
 116         struct task_struct      *thread;
 117         struct irqaction        *secondary;
 118         unsigned int            irq;
 119         unsigned int            flags;
 120         unsigned long           thread_flags;
 121         unsigned long           thread_mask;
 122         const char              *name;
 123         struct proc_dir_entry   *dir;
 124 } ____cacheline_internodealigned_in_smp;
 125
 126 extern irqreturn_t no_action(int cpl, void *dev_id);
 127
 128 extern int __must_check
 129 request_threaded_irq(unsigned int irq, irq_handler_t handler,
 130                      irq_handler_t thread_fn,
 131                      unsigned long flags, const char *name, void *dev);
 132
 133 static inline int __must_check
 134 request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
 135             const char *name, void *dev)
 136 {
 137         return request_threaded_irq(irq, handler, NULL, flags, name, dev);
 138 }
 139
 140 extern int __must_check
 141 request_any_context_irq(unsigned int irq, irq_handler_t handler,
 142                         unsigned long flags, const char *name, void *dev_id);
 143
 144 extern int __must_check
 145 request_percpu_irq(unsigned int irq, irq_handler_t handler,
 146                    const char *devname, void __percpu *percpu_dev_id);
 147
 148 extern void free_irq(unsigned int, void *);
 149 extern void free_percpu_irq(unsigned int, void __percpu *);
 150
 151 struct device;
 152
 153 extern int __must_check
 154 devm_request_threaded_irq(struct device *dev, unsigned int irq,
 155                           irq_handler_t handler, irq_handler_t thread_fn,
 156                           unsigned long irqflags, const char *devname,
 157                           void *dev_id);
 158
 159 static inline int __must_check
 160 devm_request_irq(struct device *dev, unsigned int irq, irq_handler_t handler,
 161                  unsigned long irqflags, const char *devname, void *dev_id)
 162 {
 163         return devm_request_threaded_irq(dev, irq, handler, NULL, irqflags,
 164                                          devname, dev_id);
 165 }
 166
 167 extern int __must_check
 168 devm_request_any_context_irq(struct device *dev, unsigned int irq,
 169                  irq_handler_t handler, unsigned long irqflags,
 170                  const char *devname, void *dev_id);
 171
 172 extern void devm_free_irq(struct device *dev, unsigned int irq, void *dev_id);
 173
 174 /*
 175  * On lockdep we dont want to enable hardirqs in hardirq
 176  * context. Use local_irq_enable_in_hardirq() to annotate
 177  * kernel code that has to do this nevertheless (pretty much
 178  * the only valid case is for old/broken hardware that is
 179  * insanely slow).
 180  *
 181  * NOTE: in theory this might break fragile code that relies
 182  * on hardirq delivery - in practice we dont seem to have such
 183  * places left. So the only effect should be slightly increased
 184  * irqs-off latencies.
 185  */
 186 #ifdef CONFIG_LOCKDEP
 187 # define local_irq_enable_in_hardirq()  do { } while (0)
 188 #else
 189 # define local_irq_enable_in_hardirq()  local_irq_enable()
 190 #endif
 191
 192 extern void disable_irq_nosync(unsigned int irq);
 193 extern bool disable_hardirq(unsigned int irq);
 194 extern void disable_irq(unsigned int irq);
 195 extern void disable_percpu_irq(unsigned int irq);
 196 extern void enable_irq(unsigned int irq);
 197 extern void enable_percpu_irq(unsigned int irq, unsigned int type);
 198 extern void irq_wake_thread(unsigned int irq, void *dev_id);
 199
 200 /* The following three functions are for the core kernel use only. */
 201 extern void suspend_device_irqs(void);
 202 extern void resume_device_irqs(void);
 203
 204 /**
 205  * struct irq_affinity_notify - context for notification of IRQ affinity changes
 206  * @irq:                Interrupt to which notification applies
 207  * @kref:               Reference count, for internal use
 208  * @work:               Work item, for internal use
 209  * @notify:             Function to be called on change.  This will be
 210  *                      called in process context.
 211  * @release:            Function to be called on release.  This will be
 212  *                      called in process context.  Once registered, the
 213  *                      structure must only be freed when this function is
 214  *                      called or later.
 215  */
 216 struct irq_affinity_notify {
 217         unsigned int irq;
 218         struct kref kref;
 219         struct work_struct work;
 220         void (*notify)(struct irq_affinity_notify *, const cpumask_t *mask);
 221         void (*release)(struct kref *ref);
 222 };
 223
 224 #if defined(CONFIG_SMP)
 225
 226 extern cpumask_var_t irq_default_affinity;
 227
 228 /* Internal implementation. Use the helpers below */
 229 extern int __irq_set_affinity(unsigned int irq, const struct cpumask *cpumask,
 230                               bool force);
 231
 232 /**
 233  * irq_set_affinity - Set the irq affinity of a given irq
 234  * @irq:        Interrupt to set affinity
 235  * @cpumask:    cpumask
 236  *
 237  * Fails if cpumask does not contain an online CPU
 238  */
 239 static inline int
 240 irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
 241 {
 242         return __irq_set_affinity(irq, cpumask, false);
 243 }
 244
 245 /**
 246  * irq_force_affinity - Force the irq affinity of a given irq
 247  * @irq:        Interrupt to set affinity
 248  * @cpumask:    cpumask
 249  *
 250  * Same as irq_set_affinity, but without checking the mask against
 251  * online cpus.
 252  *
 253  * Solely for low level cpu hotplug code, where we need to make per
 254  * cpu interrupts affine before the cpu becomes online.
 255  */
 256 static inline int
 257 irq_force_affinity(unsigned int irq, const struct cpumask *cpumask)
 258 {
 259         return __irq_set_affinity(irq, cpumask, true);
 260 }
 261
 262 extern int irq_can_set_affinity(unsigned int irq);
 263 extern int irq_select_affinity(unsigned int irq);
 264
 265 extern int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m);
 266
 267 extern int
 268 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify);
 269
 270 #else /* CONFIG_SMP */
 271
 272 static inline int irq_set_affinity(unsigned int irq, const struct cpumask *m)
 273 {
 274         return -EINVAL;
 275 }
 276
 277 static inline int irq_force_affinity(unsigned int irq, const struct cpumask *cpumask)
 278 {
 279         return 0;
 280 }
 281
 282 static inline int irq_can_set_affinity(unsigned int irq)
 283 {
 284         return 0;
 285 }
 286
 287 static inline int irq_select_affinity(unsigned int irq)  { return 0; }
 288
 289 static inline int irq_set_affinity_hint(unsigned int irq,
 290                                         const struct cpumask *m)
 291 {
 292         return -EINVAL;
 293 }
 294
 295 static inline int
 296 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 297 {
 298         return 0;
 299 }
 300 #endif /* CONFIG_SMP */
 301
 302 /*
 303  * Special lockdep variants of irq disabling/enabling.
 304  * These should be used for locking constructs that
 305  * know that a particular irq context which is disabled,
 306  * and which is the only irq-context user of a lock,
 307  * that it's safe to take the lock in the irq-disabled
 308  * section without disabling hardirqs.
 309  *
 310  * On !CONFIG_LOCKDEP they are equivalent to the normal
 311  * irq disable/enable methods.
 312  */
 313 static inline void disable_irq_nosync_lockdep(unsigned int irq)
 314 {
 315         disable_irq_nosync(irq);
 316 #ifdef CONFIG_LOCKDEP
 317         local_irq_disable();
 318 #endif
 319 }
 320
 321 static inline void disable_irq_nosync_lockdep_irqsave(unsigned int irq, unsigned long *flags)
 322 {
 323         disable_irq_nosync(irq);
 324 #ifdef CONFIG_LOCKDEP
 325         local_irq_save(*flags);
 326 #endif
 327 }
 328
 329 static inline void disable_irq_lockdep(unsigned int irq)
 330 {
 331         disable_irq(irq);
 332 #ifdef CONFIG_LOCKDEP
 333         local_irq_disable();
 334 #endif
 335 }
 336
 337 static inline void enable_irq_lockdep(unsigned int irq)
 338 {
 339 #ifdef CONFIG_LOCKDEP
 340         local_irq_enable();
 341 #endif
 342         enable_irq(irq);
 343 }
 344
 345 static inline void enable_irq_lockdep_irqrestore(unsigned int irq, unsigned long *flags)
 346 {
 347 #ifdef CONFIG_LOCKDEP
 348         local_irq_restore(*flags);
 349 #endif
 350         enable_irq(irq);
 351 }
 352
 353 /* IRQ wakeup (PM) control: */
 354 extern int irq_set_irq_wake(unsigned int irq, unsigned int on);
 355
 356 static inline int enable_irq_wake(unsigned int irq)
 357 {
 358         return irq_set_irq_wake(irq, 1);
 359 }
 360
 361 static inline int disable_irq_wake(unsigned int irq)
 362 {
 363         return irq_set_irq_wake(irq, 0);
 364 }
 365
 366 /*
 367  * irq_get_irqchip_state/irq_set_irqchip_state specific flags
 368  */
 369 enum irqchip_irq_state {
 370         IRQCHIP_STATE_PENDING,          /* Is interrupt pending? */
 371         IRQCHIP_STATE_ACTIVE,           /* Is interrupt in progress? */
 372         IRQCHIP_STATE_MASKED,           /* Is interrupt masked? */
 373         IRQCHIP_STATE_LINE_LEVEL,       /* Is IRQ line high? */
 374 };
 375
 376 extern int irq_get_irqchip_state(unsigned int irq, enum irqchip_irq_state which,
 377                                  bool *state);
 378 extern int irq_set_irqchip_state(unsigned int irq, enum irqchip_irq_state which,
 379                                  bool state);
 380
 381 #ifdef CONFIG_IRQ_FORCED_THREADING
 382 extern bool force_irqthreads;
 383 #else
 384 #define force_irqthreads        (0)
 385 #endif
 386
 387 #ifndef __ARCH_SET_SOFTIRQ_PENDING
 388 #define set_softirq_pending(x) (local_softirq_pending() = (x))
 389 #define or_softirq_pending(x)  (local_softirq_pending() |= (x))
 390 #endif
 391
 392 /* Some architectures might implement lazy enabling/disabling of
 393  * interrupts. In some cases, such as stop_machine, we might want
 394  * to ensure that after a local_irq_disable(), interrupts have
 395  * really been disabled in hardware. Such architectures need to
 396  * implement the following hook.
 397  */
 398 #ifndef hard_irq_disable
 399 #define hard_irq_disable()      do { } while(0)
 400 #endif
 401
 402 /* PLEASE, avoid to allocate new softirqs, if you need not _really_ high
 403    frequency threaded job scheduling. For almost all the purposes
 404    tasklets are more than enough. F.e. all serial device BHs et
 405    al. should be converted to tasklets, not to softirqs.
 406  */
 407
 408 enum
 409 {
 410         HI_SOFTIRQ=0,
 411         TIMER_SOFTIRQ,
 412         NET_TX_SOFTIRQ,
 413         NET_RX_SOFTIRQ,
 414         BLOCK_SOFTIRQ,
 415         IRQ_POLL_SOFTIRQ,
 416         TASKLET_SOFTIRQ,
 417         SCHED_SOFTIRQ,
 418         HRTIMER_SOFTIRQ, /* Unused, but kept as tools rely on the
 419                             numbering. Sigh! */
 420         RCU_SOFTIRQ,    /* Preferable RCU should always be the last softirq */
 421
 422         NR_SOFTIRQS
 423 };
 424
 425 #define SOFTIRQ_STOP_IDLE_MASK (~(1 << RCU_SOFTIRQ))
 426
 427 /* map softirq index to softirq name. update 'softirq_to_name' in
 428  * kernel/softirq.c when adding a new softirq.
 429  */
 430 extern const char * const softirq_to_name[NR_SOFTIRQS];
 431
 432 /* softirq mask and active fields moved to irq_cpustat_t in
 433  * asm/hardirq.h to get better cache usage.  KAO
 434  */
 435
 436 struct softirq_action
 437 {
 438         void    (*action)(struct softirq_action *);
 439 };
 440
 441 asmlinkage void do_softirq(void);
 442 asmlinkage void __do_softirq(void);
 443
 444 #ifdef __ARCH_HAS_DO_SOFTIRQ
 445 void do_softirq_own_stack(void);
 446 #else
 447 static inline void do_softirq_own_stack(void)
 448 {
 449         __do_softirq();
 450 }
 451 #endif
 452
 453 extern void open_softirq(int nr, void (*action)(struct softirq_action *));
 454 extern void softirq_init(void);
 455 extern void __raise_softirq_irqoff(unsigned int nr);
 456
 457 extern void raise_softirq_irqoff(unsigned int nr);
 458 extern void raise_softirq(unsigned int nr);
 459
 460 DECLARE_PER_CPU(struct task_struct *, ksoftirqd);
 461
 462 static inline struct task_struct *this_cpu_ksoftirqd(void)
 463 {
 464         return this_cpu_read(ksoftirqd);
 465 }
 466
 467 /* Tasklets --- multithreaded analogue of BHs.
 468
 469    Main feature differing them of generic softirqs: tasklet
 470    is running only on one CPU simultaneously.
 471
 472    Main feature differing them of BHs: different tasklets
 473    may be run simultaneously on different CPUs.
 474
 475    Properties:
 476    * If tasklet_schedule() is called, then tasklet is guaranteed
 477      to be executed on some cpu at least once after this.
 478    * If the tasklet is already scheduled, but its execution is still not
 479      started, it will be executed only once.
 480    * If this tasklet is already running on another CPU (or schedule is called
 481      from tasklet itself), it is rescheduled for later.
 482    * Tasklet is strictly serialized wrt itself, but not
 483      wrt another tasklets. If client needs some intertask synchronization,
 484      he makes it with spinlocks.
 485  */
 486
 487 struct tasklet_struct
 488 {
 489         struct tasklet_struct *next;
 490         unsigned long state;
 491         atomic_t count;
 492         void (*func)(unsigned long);
 493         unsigned long data;
 494 };
 495
 496 #define DECLARE_TASKLET(name, func, data) \
 497 struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(0), func, data }
 498
 499 #define DECLARE_TASKLET_DISABLED(name, func, data) \
 500 struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(1), func, data }
 501
 502
 503 enum
 504 {
 505         TASKLET_STATE_SCHED,    /* Tasklet is scheduled for execution */
 506         TASKLET_STATE_RUN       /* Tasklet is running (SMP only) */
 507 };
 508
 509 #ifdef CONFIG_SMP
 510 static inline int tasklet_trylock(struct tasklet_struct *t)
 511 {
 512         return !test_and_set_bit(TASKLET_STATE_RUN, &(t)->state);
 513 }
 514
 515 static inline void tasklet_unlock(struct tasklet_struct *t)
 516 {
 517         smp_mb__before_atomic();
 518         clear_bit(TASKLET_STATE_RUN, &(t)->state);
 519 }
 520
 521 static inline void tasklet_unlock_wait(struct tasklet_struct *t)
 522 {
 523         while (test_bit(TASKLET_STATE_RUN, &(t)->state)) { barrier(); }
 524 }
 525 #else
 526 #define tasklet_trylock(t) 1
 527 #define tasklet_unlock_wait(t) do { } while (0)
 528 #define tasklet_unlock(t) do { } while (0)
 529 #endif
 530
 531 extern void __tasklet_schedule(struct tasklet_struct *t);
 532
 533 static inline void tasklet_schedule(struct tasklet_struct *t)
 534 {
 535         if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
 536                 __tasklet_schedule(t);
 537 }
 538
 539 extern void __tasklet_hi_schedule(struct tasklet_struct *t);
 540
 541 static inline void tasklet_hi_schedule(struct tasklet_struct *t)
 542 {
 543         if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
 544                 __tasklet_hi_schedule(t);
 545 }
 546
 547 extern void __tasklet_hi_schedule_first(struct tasklet_struct *t);
 548
 549 /*
 550  * This version avoids touching any other tasklets. Needed for kmemcheck
 551  * in order not to take any page faults while enqueueing this tasklet;
 552  * consider VERY carefully whether you really need this or
 553  * tasklet_hi_schedule()...
 554  */
 555 static inline void tasklet_hi_schedule_first(struct tasklet_struct *t)
 556 {
 557         if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
 558                 __tasklet_hi_schedule_first(t);
 559 }
 560
 561
 562 static inline void tasklet_disable_nosync(struct tasklet_struct *t)
 563 {
 564         atomic_inc(&t->count);
 565         smp_mb__after_atomic();
 566 }
 567
 568 static inline void tasklet_disable(struct tasklet_struct *t)
 569 {
 570         tasklet_disable_nosync(t);
 571         tasklet_unlock_wait(t);
 572         smp_mb();
 573 }
 574
 575 static inline void tasklet_enable(struct tasklet_struct *t)
 576 {
 577         smp_mb__before_atomic();
 578         atomic_dec(&t->count);
 579 }
 580
 581 extern void tasklet_kill(struct tasklet_struct *t);
 582 extern void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu);
 583 extern void tasklet_init(struct tasklet_struct *t,
 584                          void (*func)(unsigned long), unsigned long data);
 585
 586 struct tasklet_hrtimer {
 587         struct hrtimer          timer;
 588         struct tasklet_struct   tasklet;
 589         enum hrtimer_restart    (*function)(struct hrtimer *);
 590 };
 591
 592 extern void
 593 tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer,
 594                      enum hrtimer_restart (*function)(struct hrtimer *),
 595                      clockid_t which_clock, enum hrtimer_mode mode);
 596
 597 static inline
 598 void tasklet_hrtimer_start(struct tasklet_hrtimer *ttimer, ktime_t time,
 599                            const enum hrtimer_mode mode)
 600 {
 601         hrtimer_start(&ttimer->timer, time, mode);
 602 }
 603
 604 static inline
 605 void tasklet_hrtimer_cancel(struct tasklet_hrtimer *ttimer)
 606 {
 607         hrtimer_cancel(&ttimer->timer);
 608         tasklet_kill(&ttimer->tasklet);
 609 }
 610
 611 /*
 612  * Autoprobing for irqs:
 613  *
 614  * probe_irq_on() and probe_irq_off() provide robust primitives
 615  * for accurate IRQ probing during kernel initialization.  They are
 616  * reasonably simple to use, are not "fooled" by spurious interrupts,
 617  * and, unlike other attempts at IRQ probing, they do not get hung on
 618  * stuck interrupts (such as unused PS2 mouse interfaces on ASUS boards).
 619  *
 620  * For reasonably foolproof probing, use them as follows:
 621  *
 622  * 1. clear and/or mask the device's internal interrupt.
 623  * 2. sti();
 624  * 3. irqs = probe_irq_on();      // "take over" all unassigned idle IRQs
 625  * 4. enable the device and cause it to trigger an interrupt.
 626  * 5. wait for the device to interrupt, using non-intrusive polling or a delay.
 627  * 6. irq = probe_irq_off(irqs);  // get IRQ number, 0=none, negative=multiple
 628  * 7. service the device to clear its pending interrupt.
 629  * 8. loop again if paranoia is required.
 630  *
 631  * probe_irq_on() returns a mask of allocated irq's.
 632  *
 633  * probe_irq_off() takes the mask as a parameter,
 634  * and returns the irq number which occurred,
 635  * or zero if none occurred, or a negative irq number
 636  * if more than one irq occurred.
 637  */
 638
 639 #if !defined(CONFIG_GENERIC_IRQ_PROBE)
 640 static inline unsigned long probe_irq_on(void)
 641 {
 642         return 0;
 643 }
 644 static inline int probe_irq_off(unsigned long val)
 645 {
 646         return 0;
 647 }
 648 static inline unsigned int probe_irq_mask(unsigned long val)
 649 {
 650         return 0;
 651 }
 652 #else
 653 extern unsigned long probe_irq_on(void);        /* returns 0 on failure */
 654 extern int probe_irq_off(unsigned long);        /* returns 0 or negative on failure */
 655 extern unsigned int probe_irq_mask(unsigned long);      /* returns mask of ISA interrupts */
 656 #endif
 657
 658 #ifdef CONFIG_PROC_FS
 659 /* Initialize /proc/irq/ */
 660 extern void init_irq_proc(void);
 661 #else
 662 static inline void init_irq_proc(void)
 663 {
 664 }
 665 #endif
 666
 667 struct seq_file;
 668 int show_interrupts(struct seq_file *p, void *v);
 669 int arch_show_interrupts(struct seq_file *p, int prec);
 670
 671 extern int early_irq_init(void);
 672 extern int arch_probe_nr_irqs(void);
 673 extern int arch_early_irq_init(void);
 674
 675 #endif