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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  *  'Borrowed' for ARM26 and (C) 2003 Ian Molton.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  *  This file contains the code used by various IRQ handling routines:
  13  *  asking for different IRQ's should be done through these routines
  14  *  instead of just grabbing them. Thus setups with different IRQ numbers
  15  *  shouldn't result in any weird surprises, and installing new handlers
  16  *  should be easier.
  17  *
  18  *  IRQ's are in fact implemented a bit like signal handlers for the kernel.
  19  *  Naturally it's not a 1:1 relation, but there are similarities.
  20  */
  21 #include <linux/module.h>
  22 #include <linux/ptrace.h>
  23 #include <linux/kernel_stat.h>
  24 #include <linux/signal.h>
  25 #include <linux/sched.h>
  26 #include <linux/ioport.h>
  27 #include <linux/interrupt.h>
  28 #include <linux/slab.h>
  29 #include <linux/random.h>
  30 #include <linux/smp.h>
  31 #include <linux/init.h>
  32 #include <linux/seq_file.h>
  33 #include <linux/errno.h>
  34
  35 #include <asm/irq.h>
  36 #include <asm/system.h>
  37 #include <asm/irqchip.h>
  38
  39 //FIXME - this ought to be in a header IMO
  40 void __init arc_init_irq(void);
  41
  42 /*
  43  * Maximum IRQ count.  Currently, this is arbitary.  However, it should
  44  * not be set too low to prevent false triggering.  Conversely, if it
  45  * is set too high, then you could miss a stuck IRQ.
  46  *
  47  * FIXME Maybe we ought to set a timer and re-enable the IRQ at a later time?
  48  */
  49 #define MAX_IRQ_CNT     100000
  50
  51 static volatile unsigned long irq_err_count;
  52 static DEFINE_SPINLOCK(irq_controller_lock);
  53
  54 struct irqdesc irq_desc[NR_IRQS];
  55
  56 /*
  57  * Dummy mask/unmask handler
  58  */
  59 void dummy_mask_unmask_irq(unsigned int irq)
  60 {
  61 }
  62
  63 void do_bad_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
  64 {
  65         irq_err_count += 1;
  66         printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
  67 }
  68
  69 static struct irqchip bad_chip = {
  70         .ack    = dummy_mask_unmask_irq,
  71         .mask   = dummy_mask_unmask_irq,
  72         .unmask = dummy_mask_unmask_irq,
  73 };
  74
  75 static struct irqdesc bad_irq_desc = {
  76         .chip   = &bad_chip,
  77         .handle = do_bad_IRQ,
  78         .depth  = 1,
  79 };
  80
  81 /**
  82  *      disable_irq - disable an irq and wait for completion
  83  *      @irq: Interrupt to disable
  84  *
  85  *      Disable the selected interrupt line.  We do this lazily.
  86  *
  87  *      This function may be called from IRQ context.
  88  */
  89 void disable_irq(unsigned int irq)
  90 {
  91         struct irqdesc *desc = irq_desc + irq;
  92         unsigned long flags;
  93         spin_lock_irqsave(&irq_controller_lock, flags);
  94         if (!desc->depth++)
  95                 desc->enabled = 0;
  96         spin_unlock_irqrestore(&irq_controller_lock, flags);
  97 }
  98
  99 /**
 100  *      enable_irq - enable interrupt handling on an irq
 101  *      @irq: Interrupt to enable
 102  *
 103  *      Re-enables the processing of interrupts on this IRQ line.
 104  *      Note that this may call the interrupt handler, so you may
 105  *      get unexpected results if you hold IRQs disabled.
 106  *
 107  *      This function may be called from IRQ context.
 108  */
 109 void enable_irq(unsigned int irq)
 110 {
 111         struct irqdesc *desc = irq_desc + irq;
 112         unsigned long flags;
 113         int pending = 0;
 114
 115         spin_lock_irqsave(&irq_controller_lock, flags);
 116         if (unlikely(!desc->depth)) {
 117                 printk("enable_irq(%u) unbalanced from %p\n", irq,
 118                         __builtin_return_address(0)); //FIXME bum addresses reported - why?
 119         } else if (!--desc->depth) {
 120                 desc->probing = 0;
 121                 desc->enabled = 1;
 122                 desc->chip->unmask(irq);
 123                 pending = desc->pending;
 124                 desc->pending = 0;
 125                 /*
 126                  * If the interrupt was waiting to be processed,
 127                  * retrigger it.
 128                  */
 129                 if (pending)
 130                         desc->chip->rerun(irq);
 131         }
 132         spin_unlock_irqrestore(&irq_controller_lock, flags);
 133 }
 134
 135 int show_interrupts(struct seq_file *p, void *v)
 136 {
 137         int i = *(loff_t *) v;
 138         struct irqaction * action;
 139
 140         if (i < NR_IRQS) {
 141                 action = irq_desc[i].action;
 142                 if (!action)
 143                         goto out;
 144                 seq_printf(p, "%3d: %10u ", i, kstat_irqs(i));
 145                 seq_printf(p, "  %s", action->name);
 146                 for (action = action->next; action; action = action->next) {
 147                         seq_printf(p, ", %s", action->name);
 148                 }
 149                 seq_putc(p, '\n');
 150         } else if (i == NR_IRQS) {
 151                 show_fiq_list(p, v);
 152                 seq_printf(p, "Err: %10lu\n", irq_err_count);
 153         }
 154 out:
 155         return 0;
 156 }
 157
 158 /*
 159  * IRQ lock detection.
 160  *
 161  * Hopefully, this should get us out of a few locked situations.
 162  * However, it may take a while for this to happen, since we need
 163  * a large number if IRQs to appear in the same jiffie with the
 164  * same instruction pointer (or within 2 instructions).
 165  */
 166 static int check_irq_lock(struct irqdesc *desc, int irq, struct pt_regs *regs)
 167 {
 168         unsigned long instr_ptr = instruction_pointer(regs);
 169
 170         if (desc->lck_jif == jiffies &&
 171             desc->lck_pc >= instr_ptr && desc->lck_pc < instr_ptr + 8) {
 172                 desc->lck_cnt += 1;
 173
 174                 if (desc->lck_cnt > MAX_IRQ_CNT) {
 175                         printk(KERN_ERR "IRQ LOCK: IRQ%d is locking the system, disabled\n", irq);
 176                         return 1;
 177                 }
 178         } else {
 179                 desc->lck_cnt = 0;
 180                 desc->lck_pc  = instruction_pointer(regs);
 181                 desc->lck_jif = jiffies;
 182         }
 183         return 0;
 184 }
 185
 186 static void
 187 __do_irq(unsigned int irq, struct irqaction *action, struct pt_regs *regs)
 188 {
 189         unsigned int status;
 190         int ret;
 191
 192         spin_unlock(&irq_controller_lock);
 193         if (!(action->flags & IRQF_DISABLED))
 194                 local_irq_enable();
 195
 196         status = 0;
 197         do {
 198                 ret = action->handler(irq, action->dev_id, regs);
 199                 if (ret == IRQ_HANDLED)
 200                         status |= action->flags;
 201                 action = action->next;
 202         } while (action);
 203
 204         if (status & IRQF_SAMPLE_RANDOM)
 205                 add_interrupt_randomness(irq);
 206
 207         spin_lock_irq(&irq_controller_lock);
 208 }
 209
 210 /*
 211  * This is for software-decoded IRQs.  The caller is expected to
 212  * handle the ack, clear, mask and unmask issues.
 213  */
 214 void
 215 do_simple_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 216 {
 217         struct irqaction *action;
 218         const int cpu = smp_processor_id();
 219
 220         desc->triggered = 1;
 221
 222         kstat_cpu(cpu).irqs[irq]++;
 223
 224         action = desc->action;
 225         if (action)
 226                 __do_irq(irq, desc->action, regs);
 227 }
 228
 229 /*
 230  * Most edge-triggered IRQ implementations seem to take a broken
 231  * approach to this.  Hence the complexity.
 232  */
 233 void
 234 do_edge_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 235 {
 236         const int cpu = smp_processor_id();
 237
 238         desc->triggered = 1;
 239
 240         /*
 241          * If we're currently running this IRQ, or its disabled,
 242          * we shouldn't process the IRQ.  Instead, turn on the
 243          * hardware masks.
 244          */
 245         if (unlikely(desc->running || !desc->enabled))
 246                 goto running;
 247
 248         /*
 249          * Acknowledge and clear the IRQ, but don't mask it.
 250          */
 251         desc->chip->ack(irq);
 252
 253         /*
 254          * Mark the IRQ currently in progress.
 255          */
 256         desc->running = 1;
 257
 258         kstat_cpu(cpu).irqs[irq]++;
 259
 260         do {
 261                 struct irqaction *action;
 262
 263                 action = desc->action;
 264                 if (!action)
 265                         break;
 266
 267                 if (desc->pending && desc->enabled) {
 268                         desc->pending = 0;
 269                         desc->chip->unmask(irq);
 270                 }
 271
 272                 __do_irq(irq, action, regs);
 273         } while (desc->pending);
 274
 275         desc->running = 0;
 276
 277         /*
 278          * If we were disabled or freed, shut down the handler.
 279          */
 280         if (likely(desc->action && !check_irq_lock(desc, irq, regs)))
 281                 return;
 282
 283  running:
 284         /*
 285          * We got another IRQ while this one was masked or
 286          * currently running.  Delay it.
 287          */
 288         desc->pending = 1;
 289         desc->chip->mask(irq);
 290         desc->chip->ack(irq);
 291 }
 292
 293 /*
 294  * Level-based IRQ handler.  Nice and simple.
 295  */
 296 void
 297 do_level_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 298 {
 299         struct irqaction *action;
 300         const int cpu = smp_processor_id();
 301
 302         desc->triggered = 1;
 303
 304         /*
 305          * Acknowledge, clear _AND_ disable the interrupt.
 306          */
 307         desc->chip->ack(irq);
 308
 309         if (likely(desc->enabled)) {
 310                 kstat_cpu(cpu).irqs[irq]++;
 311
 312                 /*
 313                  * Return with this interrupt masked if no action
 314                  */
 315                 action = desc->action;
 316                 if (action) {
 317                         __do_irq(irq, desc->action, regs);
 318
 319                         if (likely(desc->enabled &&
 320                                    !check_irq_lock(desc, irq, regs)))
 321                                 desc->chip->unmask(irq);
 322                 }
 323         }
 324 }
 325
 326 /*
 327  * do_IRQ handles all hardware IRQ's.  Decoded IRQs should not
 328  * come via this function.  Instead, they should provide their
 329  * own 'handler'
 330  */
 331 asmlinkage void asm_do_IRQ(int irq, struct pt_regs *regs)
 332 {
 333         struct irqdesc *desc = irq_desc + irq;
 334
 335         /*
 336          * Some hardware gives randomly wrong interrupts.  Rather
 337          * than crashing, do something sensible.
 338          */
 339         if (irq >= NR_IRQS)
 340                 desc = &bad_irq_desc;
 341
 342         irq_enter();
 343         spin_lock(&irq_controller_lock);
 344         desc->handle(irq, desc, regs);
 345         spin_unlock(&irq_controller_lock);
 346         irq_exit();
 347 }
 348
 349 void __set_irq_handler(unsigned int irq, irq_handler_t handle, int is_chained)
 350 {
 351         struct irqdesc *desc;
 352         unsigned long flags;
 353
 354         if (irq >= NR_IRQS) {
 355                 printk(KERN_ERR "Trying to install handler for IRQ%d\n", irq);
 356                 return;
 357         }
 358
 359         if (handle == NULL)
 360                 handle = do_bad_IRQ;
 361
 362         desc = irq_desc + irq;
 363
 364         if (is_chained && desc->chip == &bad_chip)
 365                 printk(KERN_WARNING "Trying to install chained handler for IRQ%d\n", irq);
 366
 367         spin_lock_irqsave(&irq_controller_lock, flags);
 368         if (handle == do_bad_IRQ) {
 369                 desc->chip->mask(irq);
 370                 desc->chip->ack(irq);
 371                 desc->depth = 1;
 372                 desc->enabled = 0;
 373         }
 374         desc->handle = handle;
 375         if (handle != do_bad_IRQ && is_chained) {
 376                 desc->valid = 0;
 377                 desc->probe_ok = 0;
 378                 desc->depth = 0;
 379                 desc->chip->unmask(irq);
 380         }
 381         spin_unlock_irqrestore(&irq_controller_lock, flags);
 382 }
 383
 384 void set_irq_chip(unsigned int irq, struct irqchip *chip)
 385 {
 386         struct irqdesc *desc;
 387         unsigned long flags;
 388
 389         if (irq >= NR_IRQS) {
 390                 printk(KERN_ERR "Trying to install chip for IRQ%d\n", irq);
 391                 return;
 392         }
 393
 394         if (chip == NULL)
 395                 chip = &bad_chip;
 396
 397         desc = irq_desc + irq;
 398         spin_lock_irqsave(&irq_controller_lock, flags);
 399         desc->chip = chip;
 400         spin_unlock_irqrestore(&irq_controller_lock, flags);
 401 }
 402
 403 int set_irq_type(unsigned int irq, unsigned int type)
 404 {
 405         struct irqdesc *desc;
 406         unsigned long flags;
 407         int ret = -ENXIO;
 408
 409         if (irq >= NR_IRQS) {
 410                 printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
 411                 return -ENODEV;
 412         }
 413
 414         desc = irq_desc + irq;
 415         if (desc->chip->type) {
 416                 spin_lock_irqsave(&irq_controller_lock, flags);
 417                 ret = desc->chip->type(irq, type);
 418                 spin_unlock_irqrestore(&irq_controller_lock, flags);
 419         }
 420
 421         return ret;
 422 }
 423
 424 void set_irq_flags(unsigned int irq, unsigned int iflags)
 425 {
 426         struct irqdesc *desc;
 427         unsigned long flags;
 428
 429         if (irq >= NR_IRQS) {
 430                 printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
 431                 return;
 432         }
 433
 434         desc = irq_desc + irq;
 435         spin_lock_irqsave(&irq_controller_lock, flags);
 436         desc->valid = (iflags & IRQF_VALID) != 0;
 437         desc->probe_ok = (iflags & IRQF_PROBE) != 0;
 438         desc->noautoenable = (iflags & IRQF_NOAUTOEN) != 0;
 439         spin_unlock_irqrestore(&irq_controller_lock, flags);
 440 }
 441
 442 int setup_irq(unsigned int irq, struct irqaction *new)
 443 {
 444         int shared = 0;
 445         struct irqaction *old, **p;
 446         unsigned long flags;
 447         struct irqdesc *desc;
 448
 449         /*
 450          * Some drivers like serial.c use request_irq() heavily,
 451          * so we have to be careful not to interfere with a
 452          * running system.
 453          */
 454         if (new->flags & IRQF_SAMPLE_RANDOM) {
 455                 /*
 456                  * This function might sleep, we want to call it first,
 457                  * outside of the atomic block.
 458                  * Yes, this might clear the entropy pool if the wrong
 459                  * driver is attempted to be loaded, without actually
 460                  * installing a new handler, but is this really a problem,
 461                  * only the sysadmin is able to do this.
 462                  */
 463                 rand_initialize_irq(irq);
 464         }
 465
 466         /*
 467          * The following block of code has to be executed atomically
 468          */
 469         desc = irq_desc + irq;
 470         spin_lock_irqsave(&irq_controller_lock, flags);
 471         p = &desc->action;
 472         if ((old = *p) != NULL) {
 473                 /* Can't share interrupts unless both agree to */
 474                 if (!(old->flags & new->flags & IRQF_SHARED)) {
 475                         spin_unlock_irqrestore(&irq_controller_lock, flags);
 476                         return -EBUSY;
 477                 }
 478
 479                 /* add new interrupt at end of irq queue */
 480                 do {
 481                         p = &old->next;
 482                         old = *p;
 483                 } while (old);
 484                 shared = 1;
 485         }
 486
 487         *p = new;
 488
 489         if (!shared) {
 490                 desc->probing = 0;
 491                 desc->running = 0;
 492                 desc->pending = 0;
 493                 desc->depth = 1;
 494                 if (!desc->noautoenable) {
 495                         desc->depth = 0;
 496                         desc->enabled = 1;
 497                         desc->chip->unmask(irq);
 498                 }
 499         }
 500
 501         spin_unlock_irqrestore(&irq_controller_lock, flags);
 502         return 0;
 503 }
 504
 505 /**
 506  *      request_irq - allocate an interrupt line
 507  *      @irq: Interrupt line to allocate
 508  *      @handler: Function to be called when the IRQ occurs
 509  *      @irqflags: Interrupt type flags
 510  *      @devname: An ascii name for the claiming device
 511  *      @dev_id: A cookie passed back to the handler function
 512  *
 513  *      This call allocates interrupt resources and enables the
 514  *      interrupt line and IRQ handling. From the point this
 515  *      call is made your handler function may be invoked. Since
 516  *      your handler function must clear any interrupt the board
 517  *      raises, you must take care both to initialise your hardware
 518  *      and to set up the interrupt handler in the right order.
 519  *
 520  *      Dev_id must be globally unique. Normally the address of the
 521  *      device data structure is used as the cookie. Since the handler
 522  *      receives this value it makes sense to use it.
 523  *
 524  *      If your interrupt is shared you must pass a non NULL dev_id
 525  *      as this is required when freeing the interrupt.
 526  *
 527  *      Flags:
 528  *
 529  *      IRQF_SHARED             Interrupt is shared
 530  *
 531  *      IRQF_DISABLED   Disable local interrupts while processing
 532  *
 533  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
 534  *
 535  */
 536
 537 //FIXME - handler used to return void - whats the significance of the change?
 538 int request_irq(unsigned int irq, irqreturn_t (*handler)(int, void *, struct pt_regs *),
 539                  unsigned long irq_flags, const char * devname, void *dev_id)
 540 {
 541         unsigned long retval;
 542         struct irqaction *action;
 543
 544         if (irq >= NR_IRQS || !irq_desc[irq].valid || !handler ||
 545             (irq_flags & IRQF_SHARED && !dev_id))
 546                 return -EINVAL;
 547
 548         action = kmalloc(sizeof(struct irqaction), GFP_KERNEL);
 549         if (!action)
 550                 return -ENOMEM;
 551
 552         action->handler = handler;
 553         action->flags = irq_flags;
 554         cpus_clear(action->mask);
 555         action->name = devname;
 556         action->next = NULL;
 557         action->dev_id = dev_id;
 558
 559         retval = setup_irq(irq, action);
 560
 561         if (retval)
 562                 kfree(action);
 563         return retval;
 564 }
 565
 566 EXPORT_SYMBOL(request_irq);
 567
 568 /**
 569  *      free_irq - free an interrupt
 570  *      @irq: Interrupt line to free
 571  *      @dev_id: Device identity to free
 572  *
 573  *      Remove an interrupt handler. The handler is removed and if the
 574  *      interrupt line is no longer in use by any driver it is disabled.
 575  *      On a shared IRQ the caller must ensure the interrupt is disabled
 576  *      on the card it drives before calling this function.
 577  *
 578  *      This function may be called from interrupt context.
 579  */
 580 void free_irq(unsigned int irq, void *dev_id)
 581 {
 582         struct irqaction * action, **p;
 583         unsigned long flags;
 584
 585         if (irq >= NR_IRQS || !irq_desc[irq].valid) {
 586                 printk(KERN_ERR "Trying to free IRQ%d\n",irq);
 587 #ifdef CONFIG_DEBUG_ERRORS
 588                 __backtrace();
 589 #endif
 590                 return;
 591         }
 592
 593         spin_lock_irqsave(&irq_controller_lock, flags);
 594         for (p = &irq_desc[irq].action; (action = *p) != NULL; p = &action->next) {
 595                 if (action->dev_id != dev_id)
 596                         continue;
 597
 598                 /* Found it - now free it */
 599                 *p = action->next;
 600                 kfree(action);
 601                 goto out;
 602         }
 603         printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
 604 #ifdef CONFIG_DEBUG_ERRORS
 605         __backtrace();
 606 #endif
 607 out:
 608         spin_unlock_irqrestore(&irq_controller_lock, flags);
 609 }
 610
 611 EXPORT_SYMBOL(free_irq);
 612
 613 /* Start the interrupt probing.  Unlike other architectures,
 614  * we don't return a mask of interrupts from probe_irq_on,
 615  * but return the number of interrupts enabled for the probe.
 616  * The interrupts which have been enabled for probing is
 617  * instead recorded in the irq_desc structure.
 618  */
 619 unsigned long probe_irq_on(void)
 620 {
 621         unsigned int i, irqs = 0;
 622         unsigned long delay;
 623
 624         /*
 625          * first snaffle up any unassigned but
 626          * probe-able interrupts
 627          */
 628         spin_lock_irq(&irq_controller_lock);
 629         for (i = 0; i < NR_IRQS; i++) {
 630                 if (!irq_desc[i].probe_ok || irq_desc[i].action)
 631                         continue;
 632
 633                 irq_desc[i].probing = 1;
 634                 irq_desc[i].triggered = 0;
 635                 if (irq_desc[i].chip->type)
 636                         irq_desc[i].chip->type(i, IRQT_PROBE);
 637                 irq_desc[i].chip->unmask(i);
 638                 irqs += 1;
 639         }
 640         spin_unlock_irq(&irq_controller_lock);
 641
 642         /*
 643          * wait for spurious interrupts to mask themselves out again
 644          */
 645         for (delay = jiffies + HZ/10; time_before(jiffies, delay); )
 646                 /* min 100ms delay */;
 647
 648         /*
 649          * now filter out any obviously spurious interrupts
 650          */
 651         spin_lock_irq(&irq_controller_lock);
 652         for (i = 0; i < NR_IRQS; i++) {
 653                 if (irq_desc[i].probing && irq_desc[i].triggered) {
 654                         irq_desc[i].probing = 0;
 655                         irqs -= 1;
 656                 }
 657         }
 658         spin_unlock_irq(&irq_controller_lock);
 659
 660         return irqs;
 661 }
 662
 663 EXPORT_SYMBOL(probe_irq_on);
 664
 665 /*
 666  * Possible return values:
 667  *  >= 0 - interrupt number
 668  *    -1 - no interrupt/many interrupts
 669  */
 670 int probe_irq_off(unsigned long irqs)
 671 {
 672         unsigned int i;
 673         int irq_found = NO_IRQ;
 674
 675         /*
 676          * look at the interrupts, and find exactly one
 677          * that we were probing has been triggered
 678          */
 679         spin_lock_irq(&irq_controller_lock);
 680         for (i = 0; i < NR_IRQS; i++) {
 681                 if (irq_desc[i].probing &&
 682                     irq_desc[i].triggered) {
 683                         if (irq_found != NO_IRQ) {
 684                                 irq_found = NO_IRQ;
 685                                 goto out;
 686                         }
 687                         irq_found = i;
 688                 }
 689         }
 690
 691         if (irq_found == -1)
 692                 irq_found = NO_IRQ;
 693 out:
 694         spin_unlock_irq(&irq_controller_lock);
 695
 696         return irq_found;
 697 }
 698
 699 EXPORT_SYMBOL(probe_irq_off);
 700
 701 void __init init_irq_proc(void)
 702 {
 703 }
 704
 705 void __init init_IRQ(void)
 706 {
 707         struct irqdesc *desc;
 708         extern void init_dma(void);
 709         int irq;
 710
 711         for (irq = 0, desc = irq_desc; irq < NR_IRQS; irq++, desc++)
 712                 *desc = bad_irq_desc;
 713
 714         arc_init_irq();
 715         init_dma();
 716 }