arch/arm/kernel/irq.c

   1 /*
   2  *  linux/arch/arm/kernel/irq.c
   3  *
   4  *  Copyright (C) 1992 Linus Torvalds
   5  *  Modifications for ARM processor Copyright (C) 1995-2000 Russell King.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  *  This file contains the code used by various IRQ handling routines:
  12  *  asking for different IRQ's should be done through these routines
  13  *  instead of just grabbing them. Thus setups with different IRQ numbers
  14  *  shouldn't result in any weird surprises, and installing new handlers
  15  *  should be easier.
  16  *
  17  *  IRQ's are in fact implemented a bit like signal handlers for the kernel.
  18  *  Naturally it's not a 1:1 relation, but there are similarities.
  19  */
  20 #include <linux/config.h>
  21 #include <linux/kernel_stat.h>
  22 #include <linux/module.h>
  23 #include <linux/signal.h>
  24 #include <linux/ioport.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/ptrace.h>
  27 #include <linux/slab.h>
  28 #include <linux/random.h>
  29 #include <linux/smp.h>
  30 #include <linux/init.h>
  31 #include <linux/seq_file.h>
  32 #include <linux/errno.h>
  33 #include <linux/list.h>
  34 #include <linux/kallsyms.h>
  35 #include <linux/proc_fs.h>
  36
  37 #include <asm/irq.h>
  38 #include <asm/system.h>
  39 #include <asm/mach/irq.h>
  40
  41 /*
  42  * Maximum IRQ count.  Currently, this is arbitary.  However, it should
  43  * not be set too low to prevent false triggering.  Conversely, if it
  44  * is set too high, then you could miss a stuck IRQ.
  45  *
  46  * Maybe we ought to set a timer and re-enable the IRQ at a later time?
  47  */
  48 #define MAX_IRQ_CNT     100000
  49
  50 static int noirqdebug;
  51 static volatile unsigned long irq_err_count;
  52 static DEFINE_SPINLOCK(irq_controller_lock);
  53 static LIST_HEAD(irq_pending);
  54
  55 struct irqdesc irq_desc[NR_IRQS];
  56 void (*init_arch_irq)(void) __initdata = NULL;
  57
  58 /*
  59  * Dummy mask/unmask handler
  60  */
  61 void dummy_mask_unmask_irq(unsigned int irq)
  62 {
  63 }
  64
  65 irqreturn_t no_action(int irq, void *dev_id, struct pt_regs *regs)
  66 {
  67         return IRQ_NONE;
  68 }
  69
  70 void do_bad_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
  71 {
  72         irq_err_count += 1;
  73         printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
  74 }
  75
  76 static struct irqchip bad_chip = {
  77         .ack    = dummy_mask_unmask_irq,
  78         .mask   = dummy_mask_unmask_irq,
  79         .unmask = dummy_mask_unmask_irq,
  80 };
  81
  82 static struct irqdesc bad_irq_desc = {
  83         .chip           = &bad_chip,
  84         .handle         = do_bad_IRQ,
  85         .pend           = LIST_HEAD_INIT(bad_irq_desc.pend),
  86         .disable_depth  = 1,
  87 };
  88
  89 #ifdef CONFIG_SMP
  90 void synchronize_irq(unsigned int irq)
  91 {
  92         struct irqdesc *desc = irq_desc + irq;
  93
  94         while (desc->running)
  95                 barrier();
  96 }
  97 EXPORT_SYMBOL(synchronize_irq);
  98
  99 #define smp_set_running(desc)   do { desc->running = 1; } while (0)
 100 #define smp_clear_running(desc) do { desc->running = 0; } while (0)
 101 #else
 102 #define smp_set_running(desc)   do { } while (0)
 103 #define smp_clear_running(desc) do { } while (0)
 104 #endif
 105
 106 /**
 107  *      disable_irq_nosync - disable an irq without waiting
 108  *      @irq: Interrupt to disable
 109  *
 110  *      Disable the selected interrupt line.  Enables and disables
 111  *      are nested.  We do this lazily.
 112  *
 113  *      This function may be called from IRQ context.
 114  */
 115 void disable_irq_nosync(unsigned int irq)
 116 {
 117         struct irqdesc *desc = irq_desc + irq;
 118         unsigned long flags;
 119
 120         spin_lock_irqsave(&irq_controller_lock, flags);
 121         desc->disable_depth++;
 122         list_del_init(&desc->pend);
 123         spin_unlock_irqrestore(&irq_controller_lock, flags);
 124 }
 125 EXPORT_SYMBOL(disable_irq_nosync);
 126
 127 /**
 128  *      disable_irq - disable an irq and wait for completion
 129  *      @irq: Interrupt to disable
 130  *
 131  *      Disable the selected interrupt line.  Enables and disables
 132  *      are nested.  This functions waits for any pending IRQ
 133  *      handlers for this interrupt to complete before returning.
 134  *      If you use this function while holding a resource the IRQ
 135  *      handler may need you will deadlock.
 136  *
 137  *      This function may be called - with care - from IRQ context.
 138  */
 139 void disable_irq(unsigned int irq)
 140 {
 141         struct irqdesc *desc = irq_desc + irq;
 142
 143         disable_irq_nosync(irq);
 144         if (desc->action)
 145                 synchronize_irq(irq);
 146 }
 147 EXPORT_SYMBOL(disable_irq);
 148
 149 /**
 150  *      enable_irq - enable interrupt handling on an irq
 151  *      @irq: Interrupt to enable
 152  *
 153  *      Re-enables the processing of interrupts on this IRQ line.
 154  *      Note that this may call the interrupt handler, so you may
 155  *      get unexpected results if you hold IRQs disabled.
 156  *
 157  *      This function may be called from IRQ context.
 158  */
 159 void enable_irq(unsigned int irq)
 160 {
 161         struct irqdesc *desc = irq_desc + irq;
 162         unsigned long flags;
 163
 164         spin_lock_irqsave(&irq_controller_lock, flags);
 165         if (unlikely(!desc->disable_depth)) {
 166                 printk("enable_irq(%u) unbalanced from %p\n", irq,
 167                         __builtin_return_address(0));
 168         } else if (!--desc->disable_depth) {
 169                 desc->probing = 0;
 170                 desc->chip->unmask(irq);
 171
 172                 /*
 173                  * If the interrupt is waiting to be processed,
 174                  * try to re-run it.  We can't directly run it
 175                  * from here since the caller might be in an
 176                  * interrupt-protected region.
 177                  */
 178                 if (desc->pending && list_empty(&desc->pend)) {
 179                         desc->pending = 0;
 180                         if (!desc->chip->retrigger ||
 181                             desc->chip->retrigger(irq))
 182                                 list_add(&desc->pend, &irq_pending);
 183                 }
 184         }
 185         spin_unlock_irqrestore(&irq_controller_lock, flags);
 186 }
 187 EXPORT_SYMBOL(enable_irq);
 188
 189 /*
 190  * Enable wake on selected irq
 191  */
 192 void enable_irq_wake(unsigned int irq)
 193 {
 194         struct irqdesc *desc = irq_desc + irq;
 195         unsigned long flags;
 196
 197         spin_lock_irqsave(&irq_controller_lock, flags);
 198         if (desc->chip->wake)
 199                 desc->chip->wake(irq, 1);
 200         spin_unlock_irqrestore(&irq_controller_lock, flags);
 201 }
 202 EXPORT_SYMBOL(enable_irq_wake);
 203
 204 void disable_irq_wake(unsigned int irq)
 205 {
 206         struct irqdesc *desc = irq_desc + irq;
 207         unsigned long flags;
 208
 209         spin_lock_irqsave(&irq_controller_lock, flags);
 210         if (desc->chip->wake)
 211                 desc->chip->wake(irq, 0);
 212         spin_unlock_irqrestore(&irq_controller_lock, flags);
 213 }
 214 EXPORT_SYMBOL(disable_irq_wake);
 215
 216 int show_interrupts(struct seq_file *p, void *v)
 217 {
 218         int i = *(loff_t *) v, cpu;
 219         struct irqaction * action;
 220         unsigned long flags;
 221
 222         if (i == 0) {
 223                 char cpuname[12];
 224
 225                 seq_printf(p, "    ");
 226                 for_each_present_cpu(cpu) {
 227                         sprintf(cpuname, "CPU%d", cpu);
 228                         seq_printf(p, " %10s", cpuname);
 229                 }
 230                 seq_putc(p, '\n');
 231         }
 232
 233         if (i < NR_IRQS) {
 234                 spin_lock_irqsave(&irq_controller_lock, flags);
 235                 action = irq_desc[i].action;
 236                 if (!action)
 237                         goto unlock;
 238
 239                 seq_printf(p, "%3d: ", i);
 240                 for_each_present_cpu(cpu)
 241                         seq_printf(p, "%10u ", kstat_cpu(cpu).irqs[i]);
 242                 seq_printf(p, "  %s", action->name);
 243                 for (action = action->next; action; action = action->next)
 244                         seq_printf(p, ", %s", action->name);
 245
 246                 seq_putc(p, '\n');
 247 unlock:
 248                 spin_unlock_irqrestore(&irq_controller_lock, flags);
 249         } else if (i == NR_IRQS) {
 250 #ifdef CONFIG_ARCH_ACORN
 251                 show_fiq_list(p, v);
 252 #endif
 253 #ifdef CONFIG_SMP
 254                 show_ipi_list(p);
 255 #endif
 256                 seq_printf(p, "Err: %10lu\n", irq_err_count);
 257         }
 258         return 0;
 259 }
 260
 261 /*
 262  * IRQ lock detection.
 263  *
 264  * Hopefully, this should get us out of a few locked situations.
 265  * However, it may take a while for this to happen, since we need
 266  * a large number if IRQs to appear in the same jiffie with the
 267  * same instruction pointer (or within 2 instructions).
 268  */
 269 static int check_irq_lock(struct irqdesc *desc, int irq, struct pt_regs *regs)
 270 {
 271         unsigned long instr_ptr = instruction_pointer(regs);
 272
 273         if (desc->lck_jif == jiffies &&
 274             desc->lck_pc >= instr_ptr && desc->lck_pc < instr_ptr + 8) {
 275                 desc->lck_cnt += 1;
 276
 277                 if (desc->lck_cnt > MAX_IRQ_CNT) {
 278                         printk(KERN_ERR "IRQ LOCK: IRQ%d is locking the system, disabled\n", irq);
 279                         return 1;
 280                 }
 281         } else {
 282                 desc->lck_cnt = 0;
 283                 desc->lck_pc  = instruction_pointer(regs);
 284                 desc->lck_jif = jiffies;
 285         }
 286         return 0;
 287 }
 288
 289 static void
 290 report_bad_irq(unsigned int irq, struct pt_regs *regs, struct irqdesc *desc, int ret)
 291 {
 292         static int count = 100;
 293         struct irqaction *action;
 294
 295         if (!count || noirqdebug)
 296                 return;
 297
 298         count--;
 299
 300         if (ret != IRQ_HANDLED && ret != IRQ_NONE) {
 301                 printk("irq%u: bogus retval mask %x\n", irq, ret);
 302         } else {
 303                 printk("irq%u: nobody cared\n", irq);
 304         }
 305         show_regs(regs);
 306         dump_stack();
 307         printk(KERN_ERR "handlers:");
 308         action = desc->action;
 309         do {
 310                 printk("\n" KERN_ERR "[<%p>]", action->handler);
 311                 print_symbol(" (%s)", (unsigned long)action->handler);
 312                 action = action->next;
 313         } while (action);
 314         printk("\n");
 315 }
 316
 317 static int
 318 __do_irq(unsigned int irq, struct irqaction *action, struct pt_regs *regs)
 319 {
 320         unsigned int status;
 321         int ret, retval = 0;
 322
 323         spin_unlock(&irq_controller_lock);
 324
 325         if (!(action->flags & SA_INTERRUPT))
 326                 local_irq_enable();
 327
 328         status = 0;
 329         do {
 330                 ret = action->handler(irq, action->dev_id, regs);
 331                 if (ret == IRQ_HANDLED)
 332                         status |= action->flags;
 333                 retval |= ret;
 334                 action = action->next;
 335         } while (action);
 336
 337         if (status & SA_SAMPLE_RANDOM)
 338                 add_interrupt_randomness(irq);
 339
 340         spin_lock_irq(&irq_controller_lock);
 341
 342         return retval;
 343 }
 344
 345 /*
 346  * This is for software-decoded IRQs.  The caller is expected to
 347  * handle the ack, clear, mask and unmask issues.
 348  */
 349 void
 350 do_simple_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 351 {
 352         struct irqaction *action;
 353         const unsigned int cpu = smp_processor_id();
 354
 355         desc->triggered = 1;
 356
 357         kstat_cpu(cpu).irqs[irq]++;
 358
 359         smp_set_running(desc);
 360
 361         action = desc->action;
 362         if (action) {
 363                 int ret = __do_irq(irq, action, regs);
 364                 if (ret != IRQ_HANDLED)
 365                         report_bad_irq(irq, regs, desc, ret);
 366         }
 367
 368         smp_clear_running(desc);
 369 }
 370
 371 /*
 372  * Most edge-triggered IRQ implementations seem to take a broken
 373  * approach to this.  Hence the complexity.
 374  */
 375 void
 376 do_edge_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 377 {
 378         const unsigned int cpu = smp_processor_id();
 379
 380         desc->triggered = 1;
 381
 382         /*
 383          * If we're currently running this IRQ, or its disabled,
 384          * we shouldn't process the IRQ.  Instead, turn on the
 385          * hardware masks.
 386          */
 387         if (unlikely(desc->running || desc->disable_depth))
 388                 goto running;
 389
 390         /*
 391          * Acknowledge and clear the IRQ, but don't mask it.
 392          */
 393         desc->chip->ack(irq);
 394
 395         /*
 396          * Mark the IRQ currently in progress.
 397          */
 398         desc->running = 1;
 399
 400         kstat_cpu(cpu).irqs[irq]++;
 401
 402         do {
 403                 struct irqaction *action;
 404
 405                 action = desc->action;
 406                 if (!action)
 407                         break;
 408
 409                 if (desc->pending && !desc->disable_depth) {
 410                         desc->pending = 0;
 411                         desc->chip->unmask(irq);
 412                 }
 413
 414                 __do_irq(irq, action, regs);
 415         } while (desc->pending && !desc->disable_depth);
 416
 417         desc->running = 0;
 418
 419         /*
 420          * If we were disabled or freed, shut down the handler.
 421          */
 422         if (likely(desc->action && !check_irq_lock(desc, irq, regs)))
 423                 return;
 424
 425  running:
 426         /*
 427          * We got another IRQ while this one was masked or
 428          * currently running.  Delay it.
 429          */
 430         desc->pending = 1;
 431         desc->chip->mask(irq);
 432         desc->chip->ack(irq);
 433 }
 434
 435 /*
 436  * Level-based IRQ handler.  Nice and simple.
 437  */
 438 void
 439 do_level_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 440 {
 441         struct irqaction *action;
 442         const unsigned int cpu = smp_processor_id();
 443
 444         desc->triggered = 1;
 445
 446         /*
 447          * Acknowledge, clear _AND_ disable the interrupt.
 448          */
 449         desc->chip->ack(irq);
 450
 451         if (likely(!desc->disable_depth)) {
 452                 kstat_cpu(cpu).irqs[irq]++;
 453
 454                 smp_set_running(desc);
 455
 456                 /*
 457                  * Return with this interrupt masked if no action
 458                  */
 459                 action = desc->action;
 460                 if (action) {
 461                         int ret = __do_irq(irq, desc->action, regs);
 462
 463                         if (ret != IRQ_HANDLED)
 464                                 report_bad_irq(irq, regs, desc, ret);
 465
 466                         if (likely(!desc->disable_depth &&
 467                                    !check_irq_lock(desc, irq, regs)))
 468                                 desc->chip->unmask(irq);
 469                 }
 470
 471                 smp_clear_running(desc);
 472         }
 473 }
 474
 475 static void do_pending_irqs(struct pt_regs *regs)
 476 {
 477         struct list_head head, *l, *n;
 478
 479         do {
 480                 struct irqdesc *desc;
 481
 482                 /*
 483                  * First, take the pending interrupts off the list.
 484                  * The act of calling the handlers may add some IRQs
 485                  * back onto the list.
 486                  */
 487                 head = irq_pending;
 488                 INIT_LIST_HEAD(&irq_pending);
 489                 head.next->prev = &head;
 490                 head.prev->next = &head;
 491
 492                 /*
 493                  * Now run each entry.  We must delete it from our
 494                  * list before calling the handler.
 495                  */
 496                 list_for_each_safe(l, n, &head) {
 497                         desc = list_entry(l, struct irqdesc, pend);
 498                         list_del_init(&desc->pend);
 499                         desc->handle(desc - irq_desc, desc, regs);
 500                 }
 501
 502                 /*
 503                  * The list must be empty.
 504                  */
 505                 BUG_ON(!list_empty(&head));
 506         } while (!list_empty(&irq_pending));
 507 }
 508
 509 /*
 510  * do_IRQ handles all hardware IRQ's.  Decoded IRQs should not
 511  * come via this function.  Instead, they should provide their
 512  * own 'handler'
 513  */
 514 asmlinkage void asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
 515 {
 516         struct irqdesc *desc = irq_desc + irq;
 517
 518         /*
 519          * Some hardware gives randomly wrong interrupts.  Rather
 520          * than crashing, do something sensible.
 521          */
 522         if (irq >= NR_IRQS)
 523                 desc = &bad_irq_desc;
 524
 525         irq_enter();
 526         spin_lock(&irq_controller_lock);
 527         desc->handle(irq, desc, regs);
 528
 529         /*
 530          * Now re-run any pending interrupts.
 531          */
 532         if (!list_empty(&irq_pending))
 533                 do_pending_irqs(regs);
 534
 535         spin_unlock(&irq_controller_lock);
 536         irq_exit();
 537 }
 538
 539 void __set_irq_handler(unsigned int irq, irq_handler_t handle, int is_chained)
 540 {
 541         struct irqdesc *desc;
 542         unsigned long flags;
 543
 544         if (irq >= NR_IRQS) {
 545                 printk(KERN_ERR "Trying to install handler for IRQ%d\n", irq);
 546                 return;
 547         }
 548
 549         if (handle == NULL)
 550                 handle = do_bad_IRQ;
 551
 552         desc = irq_desc + irq;
 553
 554         if (is_chained && desc->chip == &bad_chip)
 555                 printk(KERN_WARNING "Trying to install chained handler for IRQ%d\n", irq);
 556
 557         spin_lock_irqsave(&irq_controller_lock, flags);
 558         if (handle == do_bad_IRQ) {
 559                 desc->chip->mask(irq);
 560                 desc->chip->ack(irq);
 561                 desc->disable_depth = 1;
 562         }
 563         desc->handle = handle;
 564         if (handle != do_bad_IRQ && is_chained) {
 565                 desc->valid = 0;
 566                 desc->probe_ok = 0;
 567                 desc->disable_depth = 0;
 568                 desc->chip->unmask(irq);
 569         }
 570         spin_unlock_irqrestore(&irq_controller_lock, flags);
 571 }
 572
 573 void set_irq_chip(unsigned int irq, struct irqchip *chip)
 574 {
 575         struct irqdesc *desc;
 576         unsigned long flags;
 577
 578         if (irq >= NR_IRQS) {
 579                 printk(KERN_ERR "Trying to install chip for IRQ%d\n", irq);
 580                 return;
 581         }
 582
 583         if (chip == NULL)
 584                 chip = &bad_chip;
 585
 586         desc = irq_desc + irq;
 587         spin_lock_irqsave(&irq_controller_lock, flags);
 588         desc->chip = chip;
 589         spin_unlock_irqrestore(&irq_controller_lock, flags);
 590 }
 591
 592 int set_irq_type(unsigned int irq, unsigned int type)
 593 {
 594         struct irqdesc *desc;
 595         unsigned long flags;
 596         int ret = -ENXIO;
 597
 598         if (irq >= NR_IRQS) {
 599                 printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
 600                 return -ENODEV;
 601         }
 602
 603         desc = irq_desc + irq;
 604         if (desc->chip->type) {
 605                 spin_lock_irqsave(&irq_controller_lock, flags);
 606                 ret = desc->chip->type(irq, type);
 607                 spin_unlock_irqrestore(&irq_controller_lock, flags);
 608         }
 609
 610         return ret;
 611 }
 612 EXPORT_SYMBOL(set_irq_type);
 613
 614 void set_irq_flags(unsigned int irq, unsigned int iflags)
 615 {
 616         struct irqdesc *desc;
 617         unsigned long flags;
 618
 619         if (irq >= NR_IRQS) {
 620                 printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
 621                 return;
 622         }
 623
 624         desc = irq_desc + irq;
 625         spin_lock_irqsave(&irq_controller_lock, flags);
 626         desc->valid = (iflags & IRQF_VALID) != 0;
 627         desc->probe_ok = (iflags & IRQF_PROBE) != 0;
 628         desc->noautoenable = (iflags & IRQF_NOAUTOEN) != 0;
 629         spin_unlock_irqrestore(&irq_controller_lock, flags);
 630 }
 631
 632 int setup_irq(unsigned int irq, struct irqaction *new)
 633 {
 634         int shared = 0;
 635         struct irqaction *old, **p;
 636         unsigned long flags;
 637         struct irqdesc *desc;
 638
 639         /*
 640          * Some drivers like serial.c use request_irq() heavily,
 641          * so we have to be careful not to interfere with a
 642          * running system.
 643          */
 644         if (new->flags & SA_SAMPLE_RANDOM) {
 645                 /*
 646                  * This function might sleep, we want to call it first,
 647                  * outside of the atomic block.
 648                  * Yes, this might clear the entropy pool if the wrong
 649                  * driver is attempted to be loaded, without actually
 650                  * installing a new handler, but is this really a problem,
 651                  * only the sysadmin is able to do this.
 652                  */
 653                 rand_initialize_irq(irq);
 654         }
 655
 656         /*
 657          * The following block of code has to be executed atomically
 658          */
 659         desc = irq_desc + irq;
 660         spin_lock_irqsave(&irq_controller_lock, flags);
 661         p = &desc->action;
 662         if ((old = *p) != NULL) {
 663                 /* Can't share interrupts unless both agree to */
 664                 if (!(old->flags & new->flags & SA_SHIRQ)) {
 665                         spin_unlock_irqrestore(&irq_controller_lock, flags);
 666                         return -EBUSY;
 667                 }
 668
 669                 /* add new interrupt at end of irq queue */
 670                 do {
 671                         p = &old->next;
 672                         old = *p;
 673                 } while (old);
 674                 shared = 1;
 675         }
 676
 677         *p = new;
 678
 679         if (!shared) {
 680                 desc->probing = 0;
 681                 desc->running = 0;
 682                 desc->pending = 0;
 683                 desc->disable_depth = 1;
 684                 if (!desc->noautoenable) {
 685                         desc->disable_depth = 0;
 686                         desc->chip->unmask(irq);
 687                 }
 688         }
 689
 690         spin_unlock_irqrestore(&irq_controller_lock, flags);
 691         return 0;
 692 }
 693
 694 /**
 695  *      request_irq - allocate an interrupt line
 696  *      @irq: Interrupt line to allocate
 697  *      @handler: Function to be called when the IRQ occurs
 698  *      @irqflags: Interrupt type flags
 699  *      @devname: An ascii name for the claiming device
 700  *      @dev_id: A cookie passed back to the handler function
 701  *
 702  *      This call allocates interrupt resources and enables the
 703  *      interrupt line and IRQ handling. From the point this
 704  *      call is made your handler function may be invoked. Since
 705  *      your handler function must clear any interrupt the board
 706  *      raises, you must take care both to initialise your hardware
 707  *      and to set up the interrupt handler in the right order.
 708  *
 709  *      Dev_id must be globally unique. Normally the address of the
 710  *      device data structure is used as the cookie. Since the handler
 711  *      receives this value it makes sense to use it.
 712  *
 713  *      If your interrupt is shared you must pass a non NULL dev_id
 714  *      as this is required when freeing the interrupt.
 715  *
 716  *      Flags:
 717  *
 718  *      SA_SHIRQ                Interrupt is shared
 719  *
 720  *      SA_INTERRUPT            Disable local interrupts while processing
 721  *
 722  *      SA_SAMPLE_RANDOM        The interrupt can be used for entropy
 723  *
 724  */
 725 int request_irq(unsigned int irq, irqreturn_t (*handler)(int, void *, struct pt_regs *),
 726                  unsigned long irq_flags, const char * devname, void *dev_id)
 727 {
 728         unsigned long retval;
 729         struct irqaction *action;
 730
 731         if (irq >= NR_IRQS || !irq_desc[irq].valid || !handler ||
 732             (irq_flags & SA_SHIRQ && !dev_id))
 733                 return -EINVAL;
 734
 735         action = (struct irqaction *)kmalloc(sizeof(struct irqaction), GFP_KERNEL);
 736         if (!action)
 737                 return -ENOMEM;
 738
 739         action->handler = handler;
 740         action->flags = irq_flags;
 741         cpus_clear(action->mask);
 742         action->name = devname;
 743         action->next = NULL;
 744         action->dev_id = dev_id;
 745
 746         retval = setup_irq(irq, action);
 747
 748         if (retval)
 749                 kfree(action);
 750         return retval;
 751 }
 752
 753 EXPORT_SYMBOL(request_irq);
 754
 755 /**
 756  *      free_irq - free an interrupt
 757  *      @irq: Interrupt line to free
 758  *      @dev_id: Device identity to free
 759  *
 760  *      Remove an interrupt handler. The handler is removed and if the
 761  *      interrupt line is no longer in use by any driver it is disabled.
 762  *      On a shared IRQ the caller must ensure the interrupt is disabled
 763  *      on the card it drives before calling this function.
 764  *
 765  *      This function must not be called from interrupt context.
 766  */
 767 void free_irq(unsigned int irq, void *dev_id)
 768 {
 769         struct irqaction * action, **p;
 770         unsigned long flags;
 771
 772         if (irq >= NR_IRQS || !irq_desc[irq].valid) {
 773                 printk(KERN_ERR "Trying to free IRQ%d\n",irq);
 774                 dump_stack();
 775                 return;
 776         }
 777
 778         spin_lock_irqsave(&irq_controller_lock, flags);
 779         for (p = &irq_desc[irq].action; (action = *p) != NULL; p = &action->next) {
 780                 if (action->dev_id != dev_id)
 781                         continue;
 782
 783                 /* Found it - now free it */
 784                 *p = action->next;
 785                 break;
 786         }
 787         spin_unlock_irqrestore(&irq_controller_lock, flags);
 788
 789         if (!action) {
 790                 printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
 791                 dump_stack();
 792         } else {
 793                 synchronize_irq(irq);
 794                 kfree(action);
 795         }
 796 }
 797
 798 EXPORT_SYMBOL(free_irq);
 799
 800 static DECLARE_MUTEX(probe_sem);
 801
 802 /* Start the interrupt probing.  Unlike other architectures,
 803  * we don't return a mask of interrupts from probe_irq_on,
 804  * but return the number of interrupts enabled for the probe.
 805  * The interrupts which have been enabled for probing is
 806  * instead recorded in the irq_desc structure.
 807  */
 808 unsigned long probe_irq_on(void)
 809 {
 810         unsigned int i, irqs = 0;
 811         unsigned long delay;
 812
 813         down(&probe_sem);
 814
 815         /*
 816          * first snaffle up any unassigned but
 817          * probe-able interrupts
 818          */
 819         spin_lock_irq(&irq_controller_lock);
 820         for (i = 0; i < NR_IRQS; i++) {
 821                 if (!irq_desc[i].probe_ok || irq_desc[i].action)
 822                         continue;
 823
 824                 irq_desc[i].probing = 1;
 825                 irq_desc[i].triggered = 0;
 826                 if (irq_desc[i].chip->type)
 827                         irq_desc[i].chip->type(i, IRQT_PROBE);
 828                 irq_desc[i].chip->unmask(i);
 829                 irqs += 1;
 830         }
 831         spin_unlock_irq(&irq_controller_lock);
 832
 833         /*
 834          * wait for spurious interrupts to mask themselves out again
 835          */
 836         for (delay = jiffies + HZ/10; time_before(jiffies, delay); )
 837                 /* min 100ms delay */;
 838
 839         /*
 840          * now filter out any obviously spurious interrupts
 841          */
 842         spin_lock_irq(&irq_controller_lock);
 843         for (i = 0; i < NR_IRQS; i++) {
 844                 if (irq_desc[i].probing && irq_desc[i].triggered) {
 845                         irq_desc[i].probing = 0;
 846                         irqs -= 1;
 847                 }
 848         }
 849         spin_unlock_irq(&irq_controller_lock);
 850
 851         return irqs;
 852 }
 853
 854 EXPORT_SYMBOL(probe_irq_on);
 855
 856 unsigned int probe_irq_mask(unsigned long irqs)
 857 {
 858         unsigned int mask = 0, i;
 859
 860         spin_lock_irq(&irq_controller_lock);
 861         for (i = 0; i < 16 && i < NR_IRQS; i++)
 862                 if (irq_desc[i].probing && irq_desc[i].triggered)
 863                         mask |= 1 << i;
 864         spin_unlock_irq(&irq_controller_lock);
 865
 866         up(&probe_sem);
 867
 868         return mask;
 869 }
 870 EXPORT_SYMBOL(probe_irq_mask);
 871
 872 /*
 873  * Possible return values:
 874  *  >= 0 - interrupt number
 875  *    -1 - no interrupt/many interrupts
 876  */
 877 int probe_irq_off(unsigned long irqs)
 878 {
 879         unsigned int i;
 880         int irq_found = NO_IRQ;
 881
 882         /*
 883          * look at the interrupts, and find exactly one
 884          * that we were probing has been triggered
 885          */
 886         spin_lock_irq(&irq_controller_lock);
 887         for (i = 0; i < NR_IRQS; i++) {
 888                 if (irq_desc[i].probing &&
 889                     irq_desc[i].triggered) {
 890                         if (irq_found != NO_IRQ) {
 891                                 irq_found = NO_IRQ;
 892                                 goto out;
 893                         }
 894                         irq_found = i;
 895                 }
 896         }
 897
 898         if (irq_found == -1)
 899                 irq_found = NO_IRQ;
 900 out:
 901         spin_unlock_irq(&irq_controller_lock);
 902
 903         up(&probe_sem);
 904
 905         return irq_found;
 906 }
 907
 908 EXPORT_SYMBOL(probe_irq_off);
 909
 910 #ifdef CONFIG_SMP
 911 static void route_irq(struct irqdesc *desc, unsigned int irq, unsigned int cpu)
 912 {
 913         pr_debug("IRQ%u: moving from cpu%u to cpu%u\n", irq, desc->cpu, cpu);
 914
 915         spin_lock_irq(&irq_controller_lock);
 916         desc->cpu = cpu;
 917         desc->chip->set_cpu(desc, irq, cpu);
 918         spin_unlock_irq(&irq_controller_lock);
 919 }
 920
 921 #ifdef CONFIG_PROC_FS
 922 static int
 923 irq_affinity_read_proc(char *page, char **start, off_t off, int count,
 924                        int *eof, void *data)
 925 {
 926         struct irqdesc *desc = irq_desc + ((int)data);
 927         int len = cpumask_scnprintf(page, count, desc->affinity);
 928
 929         if (count - len < 2)
 930                 return -EINVAL;
 931         page[len++] = '\n';
 932         page[len] = '\0';
 933
 934         return len;
 935 }
 936
 937 static int
 938 irq_affinity_write_proc(struct file *file, const char __user *buffer,
 939                         unsigned long count, void *data)
 940 {
 941         unsigned int irq = (unsigned int)data;
 942         struct irqdesc *desc = irq_desc + irq;
 943         cpumask_t affinity, tmp;
 944         int ret = -EIO;
 945
 946         if (!desc->chip->set_cpu)
 947                 goto out;
 948
 949         ret = cpumask_parse(buffer, count, affinity);
 950         if (ret)
 951                 goto out;
 952
 953         cpus_and(tmp, affinity, cpu_online_map);
 954         if (cpus_empty(tmp)) {
 955                 ret = -EINVAL;
 956                 goto out;
 957         }
 958
 959         desc->affinity = affinity;
 960         route_irq(desc, irq, first_cpu(tmp));
 961         ret = count;
 962
 963  out:
 964         return ret;
 965 }
 966 #endif
 967 #endif
 968
 969 void __init init_irq_proc(void)
 970 {
 971 #if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
 972         struct proc_dir_entry *dir;
 973         int irq;
 974
 975         dir = proc_mkdir("irq", 0);
 976         if (!dir)
 977                 return;
 978
 979         for (irq = 0; irq < NR_IRQS; irq++) {
 980                 struct proc_dir_entry *entry;
 981                 struct irqdesc *desc;
 982                 char name[16];
 983
 984                 desc = irq_desc + irq;
 985                 memset(name, 0, sizeof(name));
 986                 snprintf(name, sizeof(name) - 1, "%u", irq);
 987
 988                 desc->procdir = proc_mkdir(name, dir);
 989                 if (!desc->procdir)
 990                         continue;
 991
 992                 entry = create_proc_entry("smp_affinity", 0600, desc->procdir);
 993                 if (entry) {
 994                         entry->nlink = 1;
 995                         entry->data = (void *)irq;
 996                         entry->read_proc = irq_affinity_read_proc;
 997                         entry->write_proc = irq_affinity_write_proc;
 998                 }
 999         }
1000 #endif
1001 }
1002
1003 void __init init_IRQ(void)
1004 {
1005         struct irqdesc *desc;
1006         extern void init_dma(void);
1007         int irq;
1008
1009 #ifdef CONFIG_SMP
1010         bad_irq_desc.affinity = CPU_MASK_ALL;
1011         bad_irq_desc.cpu = smp_processor_id();
1012 #endif
1013
1014         for (irq = 0, desc = irq_desc; irq < NR_IRQS; irq++, desc++) {
1015                 *desc = bad_irq_desc;
1016                 INIT_LIST_HEAD(&desc->pend);
1017         }
1018
1019         init_arch_irq();
1020         init_dma();
1021 }
1022
1023 static int __init noirqdebug_setup(char *str)
1024 {
1025         noirqdebug = 1;
1026         return 1;
1027 }
1028
1029 __setup("noirqdebug", noirqdebug_setup);