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   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  * No architecture-specific irq_finish function defined in arm/arch/irqs.h.
  60  */
  61 #ifndef irq_finish
  62 #define irq_finish(irq) do { } while (0)
  63 #endif
  64
  65 /*
  66  * Dummy mask/unmask handler
  67  */
  68 void dummy_mask_unmask_irq(unsigned int irq)
  69 {
  70 }
  71
  72 irqreturn_t no_action(int irq, void *dev_id, struct pt_regs *regs)
  73 {
  74         return IRQ_NONE;
  75 }
  76
  77 void do_bad_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
  78 {
  79         irq_err_count += 1;
  80         printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
  81 }
  82
  83 static struct irqchip bad_chip = {
  84         .ack    = dummy_mask_unmask_irq,
  85         .mask   = dummy_mask_unmask_irq,
  86         .unmask = dummy_mask_unmask_irq,
  87 };
  88
  89 static struct irqdesc bad_irq_desc = {
  90         .chip           = &bad_chip,
  91         .handle         = do_bad_IRQ,
  92         .pend           = LIST_HEAD_INIT(bad_irq_desc.pend),
  93         .disable_depth  = 1,
  94 };
  95
  96 #ifdef CONFIG_SMP
  97 void synchronize_irq(unsigned int irq)
  98 {
  99         struct irqdesc *desc = irq_desc + irq;
 100
 101         while (desc->running)
 102                 barrier();
 103 }
 104 EXPORT_SYMBOL(synchronize_irq);
 105
 106 #define smp_set_running(desc)   do { desc->running = 1; } while (0)
 107 #define smp_clear_running(desc) do { desc->running = 0; } while (0)
 108 #else
 109 #define smp_set_running(desc)   do { } while (0)
 110 #define smp_clear_running(desc) do { } while (0)
 111 #endif
 112
 113 /**
 114  *      disable_irq_nosync - disable an irq without waiting
 115  *      @irq: Interrupt to disable
 116  *
 117  *      Disable the selected interrupt line.  Enables and disables
 118  *      are nested.  We do this lazily.
 119  *
 120  *      This function may be called from IRQ context.
 121  */
 122 void disable_irq_nosync(unsigned int irq)
 123 {
 124         struct irqdesc *desc = irq_desc + irq;
 125         unsigned long flags;
 126
 127         spin_lock_irqsave(&irq_controller_lock, flags);
 128         desc->disable_depth++;
 129         list_del_init(&desc->pend);
 130         spin_unlock_irqrestore(&irq_controller_lock, flags);
 131 }
 132 EXPORT_SYMBOL(disable_irq_nosync);
 133
 134 /**
 135  *      disable_irq - disable an irq and wait for completion
 136  *      @irq: Interrupt to disable
 137  *
 138  *      Disable the selected interrupt line.  Enables and disables
 139  *      are nested.  This functions waits for any pending IRQ
 140  *      handlers for this interrupt to complete before returning.
 141  *      If you use this function while holding a resource the IRQ
 142  *      handler may need you will deadlock.
 143  *
 144  *      This function may be called - with care - from IRQ context.
 145  */
 146 void disable_irq(unsigned int irq)
 147 {
 148         struct irqdesc *desc = irq_desc + irq;
 149
 150         disable_irq_nosync(irq);
 151         if (desc->action)
 152                 synchronize_irq(irq);
 153 }
 154 EXPORT_SYMBOL(disable_irq);
 155
 156 /**
 157  *      enable_irq - enable interrupt handling on an irq
 158  *      @irq: Interrupt to enable
 159  *
 160  *      Re-enables the processing of interrupts on this IRQ line.
 161  *      Note that this may call the interrupt handler, so you may
 162  *      get unexpected results if you hold IRQs disabled.
 163  *
 164  *      This function may be called from IRQ context.
 165  */
 166 void enable_irq(unsigned int irq)
 167 {
 168         struct irqdesc *desc = irq_desc + irq;
 169         unsigned long flags;
 170
 171         spin_lock_irqsave(&irq_controller_lock, flags);
 172         if (unlikely(!desc->disable_depth)) {
 173                 printk("enable_irq(%u) unbalanced from %p\n", irq,
 174                         __builtin_return_address(0));
 175         } else if (!--desc->disable_depth) {
 176                 desc->probing = 0;
 177                 desc->chip->unmask(irq);
 178
 179                 /*
 180                  * If the interrupt is waiting to be processed,
 181                  * try to re-run it.  We can't directly run it
 182                  * from here since the caller might be in an
 183                  * interrupt-protected region.
 184                  */
 185                 if (desc->pending && list_empty(&desc->pend)) {
 186                         desc->pending = 0;
 187                         if (!desc->chip->retrigger ||
 188                             desc->chip->retrigger(irq))
 189                                 list_add(&desc->pend, &irq_pending);
 190                 }
 191         }
 192         spin_unlock_irqrestore(&irq_controller_lock, flags);
 193 }
 194 EXPORT_SYMBOL(enable_irq);
 195
 196 /*
 197  * Enable wake on selected irq
 198  */
 199 void enable_irq_wake(unsigned int irq)
 200 {
 201         struct irqdesc *desc = irq_desc + irq;
 202         unsigned long flags;
 203
 204         spin_lock_irqsave(&irq_controller_lock, flags);
 205         if (desc->chip->wake)
 206                 desc->chip->wake(irq, 1);
 207         spin_unlock_irqrestore(&irq_controller_lock, flags);
 208 }
 209 EXPORT_SYMBOL(enable_irq_wake);
 210
 211 void disable_irq_wake(unsigned int irq)
 212 {
 213         struct irqdesc *desc = irq_desc + irq;
 214         unsigned long flags;
 215
 216         spin_lock_irqsave(&irq_controller_lock, flags);
 217         if (desc->chip->wake)
 218                 desc->chip->wake(irq, 0);
 219         spin_unlock_irqrestore(&irq_controller_lock, flags);
 220 }
 221 EXPORT_SYMBOL(disable_irq_wake);
 222
 223 int show_interrupts(struct seq_file *p, void *v)
 224 {
 225         int i = *(loff_t *) v, cpu;
 226         struct irqaction * action;
 227         unsigned long flags;
 228
 229         if (i == 0) {
 230                 char cpuname[12];
 231
 232                 seq_printf(p, "    ");
 233                 for_each_present_cpu(cpu) {
 234                         sprintf(cpuname, "CPU%d", cpu);
 235                         seq_printf(p, " %10s", cpuname);
 236                 }
 237                 seq_putc(p, '\n');
 238         }
 239
 240         if (i < NR_IRQS) {
 241                 spin_lock_irqsave(&irq_controller_lock, flags);
 242                 action = irq_desc[i].action;
 243                 if (!action)
 244                         goto unlock;
 245
 246                 seq_printf(p, "%3d: ", i);
 247                 for_each_present_cpu(cpu)
 248                         seq_printf(p, "%10u ", kstat_cpu(cpu).irqs[i]);
 249                 seq_printf(p, "  %s", action->name);
 250                 for (action = action->next; action; action = action->next)
 251                         seq_printf(p, ", %s", action->name);
 252
 253                 seq_putc(p, '\n');
 254 unlock:
 255                 spin_unlock_irqrestore(&irq_controller_lock, flags);
 256         } else if (i == NR_IRQS) {
 257 #ifdef CONFIG_ARCH_ACORN
 258                 show_fiq_list(p, v);
 259 #endif
 260 #ifdef CONFIG_SMP
 261                 show_ipi_list(p);
 262 #endif
 263                 seq_printf(p, "Err: %10lu\n", irq_err_count);
 264         }
 265         return 0;
 266 }
 267
 268 /*
 269  * IRQ lock detection.
 270  *
 271  * Hopefully, this should get us out of a few locked situations.
 272  * However, it may take a while for this to happen, since we need
 273  * a large number if IRQs to appear in the same jiffie with the
 274  * same instruction pointer (or within 2 instructions).
 275  */
 276 static int check_irq_lock(struct irqdesc *desc, int irq, struct pt_regs *regs)
 277 {
 278         unsigned long instr_ptr = instruction_pointer(regs);
 279
 280         if (desc->lck_jif == jiffies &&
 281             desc->lck_pc >= instr_ptr && desc->lck_pc < instr_ptr + 8) {
 282                 desc->lck_cnt += 1;
 283
 284                 if (desc->lck_cnt > MAX_IRQ_CNT) {
 285                         printk(KERN_ERR "IRQ LOCK: IRQ%d is locking the system, disabled\n", irq);
 286                         return 1;
 287                 }
 288         } else {
 289                 desc->lck_cnt = 0;
 290                 desc->lck_pc  = instruction_pointer(regs);
 291                 desc->lck_jif = jiffies;
 292         }
 293         return 0;
 294 }
 295
 296 static void
 297 report_bad_irq(unsigned int irq, struct pt_regs *regs, struct irqdesc *desc, int ret)
 298 {
 299         static int count = 100;
 300         struct irqaction *action;
 301
 302         if (!count || noirqdebug)
 303                 return;
 304
 305         count--;
 306
 307         if (ret != IRQ_HANDLED && ret != IRQ_NONE) {
 308                 printk("irq%u: bogus retval mask %x\n", irq, ret);
 309         } else {
 310                 printk("irq%u: nobody cared\n", irq);
 311         }
 312         show_regs(regs);
 313         dump_stack();
 314         printk(KERN_ERR "handlers:");
 315         action = desc->action;
 316         do {
 317                 printk("\n" KERN_ERR "[<%p>]", action->handler);
 318                 print_symbol(" (%s)", (unsigned long)action->handler);
 319                 action = action->next;
 320         } while (action);
 321         printk("\n");
 322 }
 323
 324 static int
 325 __do_irq(unsigned int irq, struct irqaction *action, struct pt_regs *regs)
 326 {
 327         unsigned int status;
 328         int ret, retval = 0;
 329
 330         spin_unlock(&irq_controller_lock);
 331
 332         if (!(action->flags & SA_INTERRUPT))
 333                 local_irq_enable();
 334
 335         status = 0;
 336         do {
 337                 ret = action->handler(irq, action->dev_id, regs);
 338                 if (ret == IRQ_HANDLED)
 339                         status |= action->flags;
 340                 retval |= ret;
 341                 action = action->next;
 342         } while (action);
 343
 344         if (status & SA_SAMPLE_RANDOM)
 345                 add_interrupt_randomness(irq);
 346
 347         spin_lock_irq(&irq_controller_lock);
 348
 349         return retval;
 350 }
 351
 352 /*
 353  * This is for software-decoded IRQs.  The caller is expected to
 354  * handle the ack, clear, mask and unmask issues.
 355  */
 356 void
 357 do_simple_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 358 {
 359         struct irqaction *action;
 360         const unsigned int cpu = smp_processor_id();
 361
 362         desc->triggered = 1;
 363
 364         kstat_cpu(cpu).irqs[irq]++;
 365
 366         smp_set_running(desc);
 367
 368         action = desc->action;
 369         if (action) {
 370                 int ret = __do_irq(irq, action, regs);
 371                 if (ret != IRQ_HANDLED)
 372                         report_bad_irq(irq, regs, desc, ret);
 373         }
 374
 375         smp_clear_running(desc);
 376 }
 377
 378 /*
 379  * Most edge-triggered IRQ implementations seem to take a broken
 380  * approach to this.  Hence the complexity.
 381  */
 382 void
 383 do_edge_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 384 {
 385         const unsigned int cpu = smp_processor_id();
 386
 387         desc->triggered = 1;
 388
 389         /*
 390          * If we're currently running this IRQ, or its disabled,
 391          * we shouldn't process the IRQ.  Instead, turn on the
 392          * hardware masks.
 393          */
 394         if (unlikely(desc->running || desc->disable_depth))
 395                 goto running;
 396
 397         /*
 398          * Acknowledge and clear the IRQ, but don't mask it.
 399          */
 400         desc->chip->ack(irq);
 401
 402         /*
 403          * Mark the IRQ currently in progress.
 404          */
 405         desc->running = 1;
 406
 407         kstat_cpu(cpu).irqs[irq]++;
 408
 409         do {
 410                 struct irqaction *action;
 411
 412                 action = desc->action;
 413                 if (!action)
 414                         break;
 415
 416                 if (desc->pending && !desc->disable_depth) {
 417                         desc->pending = 0;
 418                         desc->chip->unmask(irq);
 419                 }
 420
 421                 __do_irq(irq, action, regs);
 422         } while (desc->pending && !desc->disable_depth);
 423
 424         desc->running = 0;
 425
 426         /*
 427          * If we were disabled or freed, shut down the handler.
 428          */
 429         if (likely(desc->action && !check_irq_lock(desc, irq, regs)))
 430                 return;
 431
 432  running:
 433         /*
 434          * We got another IRQ while this one was masked or
 435          * currently running.  Delay it.
 436          */
 437         desc->pending = 1;
 438         desc->chip->mask(irq);
 439         desc->chip->ack(irq);
 440 }
 441
 442 /*
 443  * Level-based IRQ handler.  Nice and simple.
 444  */
 445 void
 446 do_level_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 447 {
 448         struct irqaction *action;
 449         const unsigned int cpu = smp_processor_id();
 450
 451         desc->triggered = 1;
 452
 453         /*
 454          * Acknowledge, clear _AND_ disable the interrupt.
 455          */
 456         desc->chip->ack(irq);
 457
 458         if (likely(!desc->disable_depth)) {
 459                 kstat_cpu(cpu).irqs[irq]++;
 460
 461                 smp_set_running(desc);
 462
 463                 /*
 464                  * Return with this interrupt masked if no action
 465                  */
 466                 action = desc->action;
 467                 if (action) {
 468                         int ret = __do_irq(irq, desc->action, regs);
 469
 470                         if (ret != IRQ_HANDLED)
 471                                 report_bad_irq(irq, regs, desc, ret);
 472
 473                         if (likely(!desc->disable_depth &&
 474                                    !check_irq_lock(desc, irq, regs)))
 475                                 desc->chip->unmask(irq);
 476                 }
 477
 478                 smp_clear_running(desc);
 479         }
 480 }
 481
 482 static void do_pending_irqs(struct pt_regs *regs)
 483 {
 484         struct list_head head, *l, *n;
 485
 486         do {
 487                 struct irqdesc *desc;
 488
 489                 /*
 490                  * First, take the pending interrupts off the list.
 491                  * The act of calling the handlers may add some IRQs
 492                  * back onto the list.
 493                  */
 494                 head = irq_pending;
 495                 INIT_LIST_HEAD(&irq_pending);
 496                 head.next->prev = &head;
 497                 head.prev->next = &head;
 498
 499                 /*
 500                  * Now run each entry.  We must delete it from our
 501                  * list before calling the handler.
 502                  */
 503                 list_for_each_safe(l, n, &head) {
 504                         desc = list_entry(l, struct irqdesc, pend);
 505                         list_del_init(&desc->pend);
 506                         desc->handle(desc - irq_desc, desc, regs);
 507                 }
 508
 509                 /*
 510                  * The list must be empty.
 511                  */
 512                 BUG_ON(!list_empty(&head));
 513         } while (!list_empty(&irq_pending));
 514 }
 515
 516 /*
 517  * do_IRQ handles all hardware IRQ's.  Decoded IRQs should not
 518  * come via this function.  Instead, they should provide their
 519  * own 'handler'
 520  */
 521 asmlinkage void asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
 522 {
 523         struct irqdesc *desc = irq_desc + irq;
 524
 525         /*
 526          * Some hardware gives randomly wrong interrupts.  Rather
 527          * than crashing, do something sensible.
 528          */
 529         if (irq >= NR_IRQS)
 530                 desc = &bad_irq_desc;
 531
 532         irq_enter();
 533         spin_lock(&irq_controller_lock);
 534         desc->handle(irq, desc, regs);
 535
 536         /*
 537          * Now re-run any pending interrupts.
 538          */
 539         if (!list_empty(&irq_pending))
 540                 do_pending_irqs(regs);
 541
 542         irq_finish(irq);
 543
 544         spin_unlock(&irq_controller_lock);
 545         irq_exit();
 546 }
 547
 548 void __set_irq_handler(unsigned int irq, irq_handler_t handle, int is_chained)
 549 {
 550         struct irqdesc *desc;
 551         unsigned long flags;
 552
 553         if (irq >= NR_IRQS) {
 554                 printk(KERN_ERR "Trying to install handler for IRQ%d\n", irq);
 555                 return;
 556         }
 557
 558         if (handle == NULL)
 559                 handle = do_bad_IRQ;
 560
 561         desc = irq_desc + irq;
 562
 563         if (is_chained && desc->chip == &bad_chip)
 564                 printk(KERN_WARNING "Trying to install chained handler for IRQ%d\n", irq);
 565
 566         spin_lock_irqsave(&irq_controller_lock, flags);
 567         if (handle == do_bad_IRQ) {
 568                 desc->chip->mask(irq);
 569                 desc->chip->ack(irq);
 570                 desc->disable_depth = 1;
 571         }
 572         desc->handle = handle;
 573         if (handle != do_bad_IRQ && is_chained) {
 574                 desc->valid = 0;
 575                 desc->probe_ok = 0;
 576                 desc->disable_depth = 0;
 577                 desc->chip->unmask(irq);
 578         }
 579         spin_unlock_irqrestore(&irq_controller_lock, flags);
 580 }
 581
 582 void set_irq_chip(unsigned int irq, struct irqchip *chip)
 583 {
 584         struct irqdesc *desc;
 585         unsigned long flags;
 586
 587         if (irq >= NR_IRQS) {
 588                 printk(KERN_ERR "Trying to install chip for IRQ%d\n", irq);
 589                 return;
 590         }
 591
 592         if (chip == NULL)
 593                 chip = &bad_chip;
 594
 595         desc = irq_desc + irq;
 596         spin_lock_irqsave(&irq_controller_lock, flags);
 597         desc->chip = chip;
 598         spin_unlock_irqrestore(&irq_controller_lock, flags);
 599 }
 600
 601 int set_irq_type(unsigned int irq, unsigned int type)
 602 {
 603         struct irqdesc *desc;
 604         unsigned long flags;
 605         int ret = -ENXIO;
 606
 607         if (irq >= NR_IRQS) {
 608                 printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
 609                 return -ENODEV;
 610         }
 611
 612         desc = irq_desc + irq;
 613         if (desc->chip->type) {
 614                 spin_lock_irqsave(&irq_controller_lock, flags);
 615                 ret = desc->chip->type(irq, type);
 616                 spin_unlock_irqrestore(&irq_controller_lock, flags);
 617         }
 618
 619         return ret;
 620 }
 621 EXPORT_SYMBOL(set_irq_type);
 622
 623 void set_irq_flags(unsigned int irq, unsigned int iflags)
 624 {
 625         struct irqdesc *desc;
 626         unsigned long flags;
 627
 628         if (irq >= NR_IRQS) {
 629                 printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
 630                 return;
 631         }
 632
 633         desc = irq_desc + irq;
 634         spin_lock_irqsave(&irq_controller_lock, flags);
 635         desc->valid = (iflags & IRQF_VALID) != 0;
 636         desc->probe_ok = (iflags & IRQF_PROBE) != 0;
 637         desc->noautoenable = (iflags & IRQF_NOAUTOEN) != 0;
 638         spin_unlock_irqrestore(&irq_controller_lock, flags);
 639 }
 640
 641 int setup_irq(unsigned int irq, struct irqaction *new)
 642 {
 643         int shared = 0;
 644         struct irqaction *old, **p;
 645         unsigned long flags;
 646         struct irqdesc *desc;
 647
 648         /*
 649          * Some drivers like serial.c use request_irq() heavily,
 650          * so we have to be careful not to interfere with a
 651          * running system.
 652          */
 653         if (new->flags & SA_SAMPLE_RANDOM) {
 654                 /*
 655                  * This function might sleep, we want to call it first,
 656                  * outside of the atomic block.
 657                  * Yes, this might clear the entropy pool if the wrong
 658                  * driver is attempted to be loaded, without actually
 659                  * installing a new handler, but is this really a problem,
 660                  * only the sysadmin is able to do this.
 661                  */
 662                 rand_initialize_irq(irq);
 663         }
 664
 665         /*
 666          * The following block of code has to be executed atomically
 667          */
 668         desc = irq_desc + irq;
 669         spin_lock_irqsave(&irq_controller_lock, flags);
 670         p = &desc->action;
 671         if ((old = *p) != NULL) {
 672                 /* Can't share interrupts unless both agree to */
 673                 if (!(old->flags & new->flags & SA_SHIRQ)) {
 674                         spin_unlock_irqrestore(&irq_controller_lock, flags);
 675                         return -EBUSY;
 676                 }
 677
 678                 /* add new interrupt at end of irq queue */
 679                 do {
 680                         p = &old->next;
 681                         old = *p;
 682                 } while (old);
 683                 shared = 1;
 684         }
 685
 686         *p = new;
 687
 688         if (!shared) {
 689                 desc->probing = 0;
 690                 desc->running = 0;
 691                 desc->pending = 0;
 692                 desc->disable_depth = 1;
 693                 if (!desc->noautoenable) {
 694                         desc->disable_depth = 0;
 695                         desc->chip->unmask(irq);
 696                 }
 697         }
 698
 699         spin_unlock_irqrestore(&irq_controller_lock, flags);
 700         return 0;
 701 }
 702
 703 /**
 704  *      request_irq - allocate an interrupt line
 705  *      @irq: Interrupt line to allocate
 706  *      @handler: Function to be called when the IRQ occurs
 707  *      @irqflags: Interrupt type flags
 708  *      @devname: An ascii name for the claiming device
 709  *      @dev_id: A cookie passed back to the handler function
 710  *
 711  *      This call allocates interrupt resources and enables the
 712  *      interrupt line and IRQ handling. From the point this
 713  *      call is made your handler function may be invoked. Since
 714  *      your handler function must clear any interrupt the board
 715  *      raises, you must take care both to initialise your hardware
 716  *      and to set up the interrupt handler in the right order.
 717  *
 718  *      Dev_id must be globally unique. Normally the address of the
 719  *      device data structure is used as the cookie. Since the handler
 720  *      receives this value it makes sense to use it.
 721  *
 722  *      If your interrupt is shared you must pass a non NULL dev_id
 723  *      as this is required when freeing the interrupt.
 724  *
 725  *      Flags:
 726  *
 727  *      SA_SHIRQ                Interrupt is shared
 728  *
 729  *      SA_INTERRUPT            Disable local interrupts while processing
 730  *
 731  *      SA_SAMPLE_RANDOM        The interrupt can be used for entropy
 732  *
 733  */
 734 int request_irq(unsigned int irq, irqreturn_t (*handler)(int, void *, struct pt_regs *),
 735                  unsigned long irq_flags, const char * devname, void *dev_id)
 736 {
 737         unsigned long retval;
 738         struct irqaction *action;
 739
 740         if (irq >= NR_IRQS || !irq_desc[irq].valid || !handler ||
 741             (irq_flags & SA_SHIRQ && !dev_id))
 742                 return -EINVAL;
 743
 744         action = (struct irqaction *)kmalloc(sizeof(struct irqaction), GFP_KERNEL);
 745         if (!action)
 746                 return -ENOMEM;
 747
 748         action->handler = handler;
 749         action->flags = irq_flags;
 750         cpus_clear(action->mask);
 751         action->name = devname;
 752         action->next = NULL;
 753         action->dev_id = dev_id;
 754
 755         retval = setup_irq(irq, action);
 756
 757         if (retval)
 758                 kfree(action);
 759         return retval;
 760 }
 761
 762 EXPORT_SYMBOL(request_irq);
 763
 764 /**
 765  *      free_irq - free an interrupt
 766  *      @irq: Interrupt line to free
 767  *      @dev_id: Device identity to free
 768  *
 769  *      Remove an interrupt handler. The handler is removed and if the
 770  *      interrupt line is no longer in use by any driver it is disabled.
 771  *      On a shared IRQ the caller must ensure the interrupt is disabled
 772  *      on the card it drives before calling this function.
 773  *
 774  *      This function must not be called from interrupt context.
 775  */
 776 void free_irq(unsigned int irq, void *dev_id)
 777 {
 778         struct irqaction * action, **p;
 779         unsigned long flags;
 780
 781         if (irq >= NR_IRQS || !irq_desc[irq].valid) {
 782                 printk(KERN_ERR "Trying to free IRQ%d\n",irq);
 783                 dump_stack();
 784                 return;
 785         }
 786
 787         spin_lock_irqsave(&irq_controller_lock, flags);
 788         for (p = &irq_desc[irq].action; (action = *p) != NULL; p = &action->next) {
 789                 if (action->dev_id != dev_id)
 790                         continue;
 791
 792                 /* Found it - now free it */
 793                 *p = action->next;
 794                 break;
 795         }
 796         spin_unlock_irqrestore(&irq_controller_lock, flags);
 797
 798         if (!action) {
 799                 printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
 800                 dump_stack();
 801         } else {
 802                 synchronize_irq(irq);
 803                 kfree(action);
 804         }
 805 }
 806
 807 EXPORT_SYMBOL(free_irq);
 808
 809 static DECLARE_MUTEX(probe_sem);
 810
 811 /* Start the interrupt probing.  Unlike other architectures,
 812  * we don't return a mask of interrupts from probe_irq_on,
 813  * but return the number of interrupts enabled for the probe.
 814  * The interrupts which have been enabled for probing is
 815  * instead recorded in the irq_desc structure.
 816  */
 817 unsigned long probe_irq_on(void)
 818 {
 819         unsigned int i, irqs = 0;
 820         unsigned long delay;
 821
 822         down(&probe_sem);
 823
 824         /*
 825          * first snaffle up any unassigned but
 826          * probe-able interrupts
 827          */
 828         spin_lock_irq(&irq_controller_lock);
 829         for (i = 0; i < NR_IRQS; i++) {
 830                 if (!irq_desc[i].probe_ok || irq_desc[i].action)
 831                         continue;
 832
 833                 irq_desc[i].probing = 1;
 834                 irq_desc[i].triggered = 0;
 835                 if (irq_desc[i].chip->type)
 836                         irq_desc[i].chip->type(i, IRQT_PROBE);
 837                 irq_desc[i].chip->unmask(i);
 838                 irqs += 1;
 839         }
 840         spin_unlock_irq(&irq_controller_lock);
 841
 842         /*
 843          * wait for spurious interrupts to mask themselves out again
 844          */
 845         for (delay = jiffies + HZ/10; time_before(jiffies, delay); )
 846                 /* min 100ms delay */;
 847
 848         /*
 849          * now filter out any obviously spurious interrupts
 850          */
 851         spin_lock_irq(&irq_controller_lock);
 852         for (i = 0; i < NR_IRQS; i++) {
 853                 if (irq_desc[i].probing && irq_desc[i].triggered) {
 854                         irq_desc[i].probing = 0;
 855                         irqs -= 1;
 856                 }
 857         }
 858         spin_unlock_irq(&irq_controller_lock);
 859
 860         return irqs;
 861 }
 862
 863 EXPORT_SYMBOL(probe_irq_on);
 864
 865 unsigned int probe_irq_mask(unsigned long irqs)
 866 {
 867         unsigned int mask = 0, i;
 868
 869         spin_lock_irq(&irq_controller_lock);
 870         for (i = 0; i < 16 && i < NR_IRQS; i++)
 871                 if (irq_desc[i].probing && irq_desc[i].triggered)
 872                         mask |= 1 << i;
 873         spin_unlock_irq(&irq_controller_lock);
 874
 875         up(&probe_sem);
 876
 877         return mask;
 878 }
 879 EXPORT_SYMBOL(probe_irq_mask);
 880
 881 /*
 882  * Possible return values:
 883  *  >= 0 - interrupt number
 884  *    -1 - no interrupt/many interrupts
 885  */
 886 int probe_irq_off(unsigned long irqs)
 887 {
 888         unsigned int i;
 889         int irq_found = NO_IRQ;
 890
 891         /*
 892          * look at the interrupts, and find exactly one
 893          * that we were probing has been triggered
 894          */
 895         spin_lock_irq(&irq_controller_lock);
 896         for (i = 0; i < NR_IRQS; i++) {
 897                 if (irq_desc[i].probing &&
 898                     irq_desc[i].triggered) {
 899                         if (irq_found != NO_IRQ) {
 900                                 irq_found = NO_IRQ;
 901                                 goto out;
 902                         }
 903                         irq_found = i;
 904                 }
 905         }
 906
 907         if (irq_found == -1)
 908                 irq_found = NO_IRQ;
 909 out:
 910         spin_unlock_irq(&irq_controller_lock);
 911
 912         up(&probe_sem);
 913
 914         return irq_found;
 915 }
 916
 917 EXPORT_SYMBOL(probe_irq_off);
 918
 919 #ifdef CONFIG_SMP
 920 static void route_irq(struct irqdesc *desc, unsigned int irq, unsigned int cpu)
 921 {
 922         pr_debug("IRQ%u: moving from cpu%u to cpu%u\n", irq, desc->cpu, cpu);
 923
 924         spin_lock_irq(&irq_controller_lock);
 925         desc->cpu = cpu;
 926         desc->chip->set_cpu(desc, irq, cpu);
 927         spin_unlock_irq(&irq_controller_lock);
 928 }
 929
 930 #ifdef CONFIG_PROC_FS
 931 static int
 932 irq_affinity_read_proc(char *page, char **start, off_t off, int count,
 933                        int *eof, void *data)
 934 {
 935         struct irqdesc *desc = irq_desc + ((int)data);
 936         int len = cpumask_scnprintf(page, count, desc->affinity);
 937
 938         if (count - len < 2)
 939                 return -EINVAL;
 940         page[len++] = '\n';
 941         page[len] = '\0';
 942
 943         return len;
 944 }
 945
 946 static int
 947 irq_affinity_write_proc(struct file *file, const char __user *buffer,
 948                         unsigned long count, void *data)
 949 {
 950         unsigned int irq = (unsigned int)data;
 951         struct irqdesc *desc = irq_desc + irq;
 952         cpumask_t affinity, tmp;
 953         int ret = -EIO;
 954
 955         if (!desc->chip->set_cpu)
 956                 goto out;
 957
 958         ret = cpumask_parse(buffer, count, affinity);
 959         if (ret)
 960                 goto out;
 961
 962         cpus_and(tmp, affinity, cpu_online_map);
 963         if (cpus_empty(tmp)) {
 964                 ret = -EINVAL;
 965                 goto out;
 966         }
 967
 968         desc->affinity = affinity;
 969         route_irq(desc, irq, first_cpu(tmp));
 970         ret = count;
 971
 972  out:
 973         return ret;
 974 }
 975 #endif
 976 #endif
 977
 978 void __init init_irq_proc(void)
 979 {
 980 #if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)
 981         struct proc_dir_entry *dir;
 982         int irq;
 983
 984         dir = proc_mkdir("irq", 0);
 985         if (!dir)
 986                 return;
 987
 988         for (irq = 0; irq < NR_IRQS; irq++) {
 989                 struct proc_dir_entry *entry;
 990                 struct irqdesc *desc;
 991                 char name[16];
 992
 993                 desc = irq_desc + irq;
 994                 memset(name, 0, sizeof(name));
 995                 snprintf(name, sizeof(name) - 1, "%u", irq);
 996
 997                 desc->procdir = proc_mkdir(name, dir);
 998                 if (!desc->procdir)
 999                         continue;
1000
1001                 entry = create_proc_entry("smp_affinity", 0600, desc->procdir);
1002                 if (entry) {
1003                         entry->nlink = 1;
1004                         entry->data = (void *)irq;
1005                         entry->read_proc = irq_affinity_read_proc;
1006                         entry->write_proc = irq_affinity_write_proc;
1007                 }
1008         }
1009 #endif
1010 }
1011
1012 void __init init_IRQ(void)
1013 {
1014         struct irqdesc *desc;
1015         extern void init_dma(void);
1016         int irq;
1017
1018 #ifdef CONFIG_SMP
1019         bad_irq_desc.affinity = CPU_MASK_ALL;
1020         bad_irq_desc.cpu = smp_processor_id();
1021 #endif
1022
1023         for (irq = 0, desc = irq_desc; irq < NR_IRQS; irq++, desc++) {
1024                 *desc = bad_irq_desc;
1025                 INIT_LIST_HEAD(&desc->pend);
1026         }
1027
1028         init_arch_irq();
1029         init_dma();
1030 }
1031
1032 static int __init noirqdebug_setup(char *str)
1033 {
1034         noirqdebug = 1;
1035         return 1;
1036 }
1037
1038 __setup("noirqdebug", noirqdebug_setup);