arch/arm26/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  *  '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/config.h>
  22 #include <linux/module.h>
  23 #include <linux/ptrace.h>
  24 #include <linux/kernel_stat.h>
  25 #include <linux/signal.h>
  26 #include <linux/sched.h>
  27 #include <linux/ioport.h>
  28 #include <linux/interrupt.h>
  29 #include <linux/slab.h>
  30 #include <linux/random.h>
  31 #include <linux/smp.h>
  32 #include <linux/init.h>
  33 #include <linux/seq_file.h>
  34 #include <linux/errno.h>
  35
  36 #include <asm/irq.h>
  37 #include <asm/system.h>
  38 #include <asm/irqchip.h>
  39
  40 //FIXME - this ought to be in a header IMO
  41 void __init arc_init_irq(void);
  42
  43 /*
  44  * Maximum IRQ count.  Currently, this is arbitary.  However, it should
  45  * not be set too low to prevent false triggering.  Conversely, if it
  46  * is set too high, then you could miss a stuck IRQ.
  47  *
  48  * FIXME Maybe we ought to set a timer and re-enable the IRQ at a later time?
  49  */
  50 #define MAX_IRQ_CNT     100000
  51
  52 static volatile unsigned long irq_err_count;
  53 static DEFINE_SPINLOCK(irq_controller_lock);
  54
  55 struct irqdesc irq_desc[NR_IRQS];
  56
  57 /*
  58  * Dummy mask/unmask handler
  59  */
  60 void dummy_mask_unmask_irq(unsigned int irq)
  61 {
  62 }
  63
  64 void do_bad_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
  65 {
  66         irq_err_count += 1;
  67         printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
  68 }
  69
  70 static struct irqchip bad_chip = {
  71         .ack    = dummy_mask_unmask_irq,
  72         .mask   = dummy_mask_unmask_irq,
  73         .unmask = dummy_mask_unmask_irq,
  74 };
  75
  76 static struct irqdesc bad_irq_desc = {
  77         .chip   = &bad_chip,
  78         .handle = do_bad_IRQ,
  79         .depth  = 1,
  80 };
  81
  82 /**
  83  *      disable_irq - disable an irq and wait for completion
  84  *      @irq: Interrupt to disable
  85  *
  86  *      Disable the selected interrupt line.  We do this lazily.
  87  *
  88  *      This function may be called from IRQ context.
  89  */
  90 void disable_irq(unsigned int irq)
  91 {
  92         struct irqdesc *desc = irq_desc + irq;
  93         unsigned long flags;
  94         spin_lock_irqsave(&irq_controller_lock, flags);
  95         if (!desc->depth++)
  96                 desc->enabled = 0;
  97         spin_unlock_irqrestore(&irq_controller_lock, flags);
  98 }
  99
 100 /**
 101  *      enable_irq - enable interrupt handling on an irq
 102  *      @irq: Interrupt to enable
 103  *
 104  *      Re-enables the processing of interrupts on this IRQ line.
 105  *      Note that this may call the interrupt handler, so you may
 106  *      get unexpected results if you hold IRQs disabled.
 107  *
 108  *      This function may be called from IRQ context.
 109  */
 110 void enable_irq(unsigned int irq)
 111 {
 112         struct irqdesc *desc = irq_desc + irq;
 113         unsigned long flags;
 114         int pending = 0;
 115
 116         spin_lock_irqsave(&irq_controller_lock, flags);
 117         if (unlikely(!desc->depth)) {
 118                 printk("enable_irq(%u) unbalanced from %p\n", irq,
 119                         __builtin_return_address(0)); //FIXME bum addresses reported - why?
 120         } else if (!--desc->depth) {
 121                 desc->probing = 0;
 122                 desc->enabled = 1;
 123                 desc->chip->unmask(irq);
 124                 pending = desc->pending;
 125                 desc->pending = 0;
 126                 /*
 127                  * If the interrupt was waiting to be processed,
 128                  * retrigger it.
 129                  */
 130                 if (pending)
 131                         desc->chip->rerun(irq);
 132         }
 133         spin_unlock_irqrestore(&irq_controller_lock, flags);
 134 }
 135
 136 int show_interrupts(struct seq_file *p, void *v)
 137 {
 138         int i = *(loff_t *) v;
 139         struct irqaction * action;
 140
 141         if (i < NR_IRQS) {
 142                 action = irq_desc[i].action;
 143                 if (!action)
 144                         goto out;
 145                 seq_printf(p, "%3d: %10u ", i, kstat_irqs(i));
 146                 seq_printf(p, "  %s", action->name);
 147                 for (action = action->next; action; action = action->next) {
 148                         seq_printf(p, ", %s", action->name);
 149                 }
 150                 seq_putc(p, '\n');
 151         } else if (i == NR_IRQS) {
 152                 show_fiq_list(p, v);
 153                 seq_printf(p, "Err: %10lu\n", irq_err_count);
 154         }
 155 out:
 156         return 0;
 157 }
 158
 159 /*
 160  * IRQ lock detection.
 161  *
 162  * Hopefully, this should get us out of a few locked situations.
 163  * However, it may take a while for this to happen, since we need
 164  * a large number if IRQs to appear in the same jiffie with the
 165  * same instruction pointer (or within 2 instructions).
 166  */
 167 static int check_irq_lock(struct irqdesc *desc, int irq, struct pt_regs *regs)
 168 {
 169         unsigned long instr_ptr = instruction_pointer(regs);
 170
 171         if (desc->lck_jif == jiffies &&
 172             desc->lck_pc >= instr_ptr && desc->lck_pc < instr_ptr + 8) {
 173                 desc->lck_cnt += 1;
 174
 175                 if (desc->lck_cnt > MAX_IRQ_CNT) {
 176                         printk(KERN_ERR "IRQ LOCK: IRQ%d is locking the system, disabled\n", irq);
 177                         return 1;
 178                 }
 179         } else {
 180                 desc->lck_cnt = 0;
 181                 desc->lck_pc  = instruction_pointer(regs);
 182                 desc->lck_jif = jiffies;
 183         }
 184         return 0;
 185 }
 186
 187 static void
 188 __do_irq(unsigned int irq, struct irqaction *action, struct pt_regs *regs)
 189 {
 190         unsigned int status;
 191         int ret;
 192
 193         spin_unlock(&irq_controller_lock);
 194         if (!(action->flags & SA_INTERRUPT))
 195                 local_irq_enable();
 196
 197         status = 0;
 198         do {
 199                 ret = action->handler(irq, action->dev_id, regs);
 200                 if (ret == IRQ_HANDLED)
 201                         status |= action->flags;
 202                 action = action->next;
 203         } while (action);
 204
 205         if (status & SA_SAMPLE_RANDOM)
 206                 add_interrupt_randomness(irq);
 207
 208         spin_lock_irq(&irq_controller_lock);
 209 }
 210
 211 /*
 212  * This is for software-decoded IRQs.  The caller is expected to
 213  * handle the ack, clear, mask and unmask issues.
 214  */
 215 void
 216 do_simple_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 217 {
 218         struct irqaction *action;
 219         const int cpu = smp_processor_id();
 220
 221         desc->triggered = 1;
 222
 223         kstat_cpu(cpu).irqs[irq]++;
 224
 225         action = desc->action;
 226         if (action)
 227                 __do_irq(irq, desc->action, regs);
 228 }
 229
 230 /*
 231  * Most edge-triggered IRQ implementations seem to take a broken
 232  * approach to this.  Hence the complexity.
 233  */
 234 void
 235 do_edge_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 236 {
 237         const int cpu = smp_processor_id();
 238
 239         desc->triggered = 1;
 240
 241         /*
 242          * If we're currently running this IRQ, or its disabled,
 243          * we shouldn't process the IRQ.  Instead, turn on the
 244          * hardware masks.
 245          */
 246         if (unlikely(desc->running || !desc->enabled))
 247                 goto running;
 248
 249         /*
 250          * Acknowledge and clear the IRQ, but don't mask it.
 251          */
 252         desc->chip->ack(irq);
 253
 254         /*
 255          * Mark the IRQ currently in progress.
 256          */
 257         desc->running = 1;
 258
 259         kstat_cpu(cpu).irqs[irq]++;
 260
 261         do {
 262                 struct irqaction *action;
 263
 264                 action = desc->action;
 265                 if (!action)
 266                         break;
 267
 268                 if (desc->pending && desc->enabled) {
 269                         desc->pending = 0;
 270                         desc->chip->unmask(irq);
 271                 }
 272
 273                 __do_irq(irq, action, regs);
 274         } while (desc->pending);
 275
 276         desc->running = 0;
 277
 278         /*
 279          * If we were disabled or freed, shut down the handler.
 280          */
 281         if (likely(desc->action && !check_irq_lock(desc, irq, regs)))
 282                 return;
 283
 284  running:
 285         /*
 286          * We got another IRQ while this one was masked or
 287          * currently running.  Delay it.
 288          */
 289         desc->pending = 1;
 290         desc->chip->mask(irq);
 291         desc->chip->ack(irq);
 292 }
 293
 294 /*
 295  * Level-based IRQ handler.  Nice and simple.
 296  */
 297 void
 298 do_level_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
 299 {
 300         struct irqaction *action;
 301         const int cpu = smp_processor_id();
 302
 303         desc->triggered = 1;
 304
 305         /*
 306          * Acknowledge, clear _AND_ disable the interrupt.
 307          */
 308         desc->chip->ack(irq);
 309
 310         if (likely(desc->enabled)) {
 311                 kstat_cpu(cpu).irqs[irq]++;
 312
 313                 /*
 314                  * Return with this interrupt masked if no action
 315                  */
 316                 action = desc->action;
 317                 if (action) {
 318                         __do_irq(irq, desc->action, regs);
 319
 320                         if (likely(desc->enabled &&
 321                                    !check_irq_lock(desc, irq, regs)))
 322                                 desc->chip->unmask(irq);
 323                 }
 324         }
 325 }
 326
 327 /*
 328  * do_IRQ handles all hardware IRQ's.  Decoded IRQs should not
 329  * come via this function.  Instead, they should provide their
 330  * own 'handler'
 331  */
 332 asmlinkage void asm_do_IRQ(int irq, struct pt_regs *regs)
 333 {
 334         struct irqdesc *desc = irq_desc + irq;
 335
 336         /*
 337          * Some hardware gives randomly wrong interrupts.  Rather
 338          * than crashing, do something sensible.
 339          */
 340         if (irq >= NR_IRQS)
 341                 desc = &bad_irq_desc;
 342
 343         irq_enter();
 344         spin_lock(&irq_controller_lock);
 345         desc->handle(irq, desc, regs);
 346         spin_unlock(&irq_controller_lock);
 347         irq_exit();
 348 }
 349
 350 void __set_irq_handler(unsigned int irq, irq_handler_t handle, int is_chained)
 351 {
 352         struct irqdesc *desc;
 353         unsigned long flags;
 354
 355         if (irq >= NR_IRQS) {
 356                 printk(KERN_ERR "Trying to install handler for IRQ%d\n", irq);
 357                 return;
 358         }
 359
 360         if (handle == NULL)
 361                 handle = do_bad_IRQ;
 362
 363         desc = irq_desc + irq;
 364
 365         if (is_chained && desc->chip == &bad_chip)
 366                 printk(KERN_WARNING "Trying to install chained handler for IRQ%d\n", irq);
 367
 368         spin_lock_irqsave(&irq_controller_lock, flags);
 369         if (handle == do_bad_IRQ) {
 370                 desc->chip->mask(irq);
 371                 desc->chip->ack(irq);
 372                 desc->depth = 1;
 373                 desc->enabled = 0;
 374         }
 375         desc->handle = handle;
 376         if (handle != do_bad_IRQ && is_chained) {
 377                 desc->valid = 0;
 378                 desc->probe_ok = 0;
 379                 desc->depth = 0;
 380                 desc->chip->unmask(irq);
 381         }
 382         spin_unlock_irqrestore(&irq_controller_lock, flags);
 383 }
 384
 385 void set_irq_chip(unsigned int irq, struct irqchip *chip)
 386 {
 387         struct irqdesc *desc;
 388         unsigned long flags;
 389
 390         if (irq >= NR_IRQS) {
 391                 printk(KERN_ERR "Trying to install chip for IRQ%d\n", irq);
 392                 return;
 393         }
 394
 395         if (chip == NULL)
 396                 chip = &bad_chip;
 397
 398         desc = irq_desc + irq;
 399         spin_lock_irqsave(&irq_controller_lock, flags);
 400         desc->chip = chip;
 401         spin_unlock_irqrestore(&irq_controller_lock, flags);
 402 }
 403
 404 int set_irq_type(unsigned int irq, unsigned int type)
 405 {
 406         struct irqdesc *desc;
 407         unsigned long flags;
 408         int ret = -ENXIO;
 409
 410         if (irq >= NR_IRQS) {
 411                 printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
 412                 return -ENODEV;
 413         }
 414
 415         desc = irq_desc + irq;
 416         if (desc->chip->type) {
 417                 spin_lock_irqsave(&irq_controller_lock, flags);
 418                 ret = desc->chip->type(irq, type);
 419                 spin_unlock_irqrestore(&irq_controller_lock, flags);
 420         }
 421
 422         return ret;
 423 }
 424
 425 void set_irq_flags(unsigned int irq, unsigned int iflags)
 426 {
 427         struct irqdesc *desc;
 428         unsigned long flags;
 429
 430         if (irq >= NR_IRQS) {
 431                 printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
 432                 return;
 433         }
 434
 435         desc = irq_desc + irq;
 436         spin_lock_irqsave(&irq_controller_lock, flags);
 437         desc->valid = (iflags & IRQF_VALID) != 0;
 438         desc->probe_ok = (iflags & IRQF_PROBE) != 0;
 439         desc->noautoenable = (iflags & IRQF_NOAUTOEN) != 0;
 440         spin_unlock_irqrestore(&irq_controller_lock, flags);
 441 }
 442
 443 int setup_irq(unsigned int irq, struct irqaction *new)
 444 {
 445         int shared = 0;
 446         struct irqaction *old, **p;
 447         unsigned long flags;
 448         struct irqdesc *desc;
 449
 450         /*
 451          * Some drivers like serial.c use request_irq() heavily,
 452          * so we have to be careful not to interfere with a
 453          * running system.
 454          */
 455         if (new->flags & SA_SAMPLE_RANDOM) {
 456                 /*
 457                  * This function might sleep, we want to call it first,
 458                  * outside of the atomic block.
 459                  * Yes, this might clear the entropy pool if the wrong
 460                  * driver is attempted to be loaded, without actually
 461                  * installing a new handler, but is this really a problem,
 462                  * only the sysadmin is able to do this.
 463                  */
 464                 rand_initialize_irq(irq);
 465         }
 466
 467         /*
 468          * The following block of code has to be executed atomically
 469          */
 470         desc = irq_desc + irq;
 471         spin_lock_irqsave(&irq_controller_lock, flags);
 472         p = &desc->action;
 473         if ((old = *p) != NULL) {
 474                 /* Can't share interrupts unless both agree to */
 475                 if (!(old->flags & new->flags & SA_SHIRQ)) {
 476                         spin_unlock_irqrestore(&irq_controller_lock, flags);
 477                         return -EBUSY;
 478                 }
 479
 480                 /* add new interrupt at end of irq queue */
 481                 do {
 482                         p = &old->next;
 483                         old = *p;
 484                 } while (old);
 485                 shared = 1;
 486         }
 487
 488         *p = new;
 489
 490         if (!shared) {
 491                 desc->probing = 0;
 492                 desc->running = 0;
 493                 desc->pending = 0;
 494                 desc->depth = 1;
 495                 if (!desc->noautoenable) {
 496                         desc->depth = 0;
 497                         desc->enabled = 1;
 498                         desc->chip->unmask(irq);
 499                 }
 500         }
 501
 502         spin_unlock_irqrestore(&irq_controller_lock, flags);
 503         return 0;
 504 }
 505
 506 /**
 507  *      request_irq - allocate an interrupt line
 508  *      @irq: Interrupt line to allocate
 509  *      @handler: Function to be called when the IRQ occurs
 510  *      @irqflags: Interrupt type flags
 511  *      @devname: An ascii name for the claiming device
 512  *      @dev_id: A cookie passed back to the handler function
 513  *
 514  *      This call allocates interrupt resources and enables the
 515  *      interrupt line and IRQ handling. From the point this
 516  *      call is made your handler function may be invoked. Since
 517  *      your handler function must clear any interrupt the board
 518  *      raises, you must take care both to initialise your hardware
 519  *      and to set up the interrupt handler in the right order.
 520  *
 521  *      Dev_id must be globally unique. Normally the address of the
 522  *      device data structure is used as the cookie. Since the handler
 523  *      receives this value it makes sense to use it.
 524  *
 525  *      If your interrupt is shared you must pass a non NULL dev_id
 526  *      as this is required when freeing the interrupt.
 527  *
 528  *      Flags:
 529  *
 530  *      SA_SHIRQ                Interrupt is shared
 531  *
 532  *      SA_INTERRUPT            Disable local interrupts while processing
 533  *
 534  *      SA_SAMPLE_RANDOM        The interrupt can be used for entropy
 535  *
 536  */
 537
 538 //FIXME - handler used to return void - whats the significance of the change?
 539 int request_irq(unsigned int irq, irqreturn_t (*handler)(int, void *, struct pt_regs *),
 540                  unsigned long irq_flags, const char * devname, void *dev_id)
 541 {
 542         unsigned long retval;
 543         struct irqaction *action;
 544
 545         if (irq >= NR_IRQS || !irq_desc[irq].valid || !handler ||
 546             (irq_flags & SA_SHIRQ && !dev_id))
 547                 return -EINVAL;
 548
 549         action = (struct irqaction *)kmalloc(sizeof(struct irqaction), GFP_KERNEL);
 550         if (!action)
 551                 return -ENOMEM;
 552
 553         action->handler = handler;
 554         action->flags = irq_flags;
 555         cpus_clear(action->mask);
 556         action->name = devname;
 557         action->next = NULL;
 558         action->dev_id = dev_id;
 559
 560         retval = setup_irq(irq, action);
 561
 562         if (retval)
 563                 kfree(action);
 564         return retval;
 565 }
 566
 567 EXPORT_SYMBOL(request_irq);
 568
 569 /**
 570  *      free_irq - free an interrupt
 571  *      @irq: Interrupt line to free
 572  *      @dev_id: Device identity to free
 573  *
 574  *      Remove an interrupt handler. The handler is removed and if the
 575  *      interrupt line is no longer in use by any driver it is disabled.
 576  *      On a shared IRQ the caller must ensure the interrupt is disabled
 577  *      on the card it drives before calling this function.
 578  *
 579  *      This function may be called from interrupt context.
 580  */
 581 void free_irq(unsigned int irq, void *dev_id)
 582 {
 583         struct irqaction * action, **p;
 584         unsigned long flags;
 585
 586         if (irq >= NR_IRQS || !irq_desc[irq].valid) {
 587                 printk(KERN_ERR "Trying to free IRQ%d\n",irq);
 588 #ifdef CONFIG_DEBUG_ERRORS
 589                 __backtrace();
 590 #endif
 591                 return;
 592         }
 593
 594         spin_lock_irqsave(&irq_controller_lock, flags);
 595         for (p = &irq_desc[irq].action; (action = *p) != NULL; p = &action->next) {
 596                 if (action->dev_id != dev_id)
 597                         continue;
 598
 599                 /* Found it - now free it */
 600                 *p = action->next;
 601                 kfree(action);
 602                 goto out;
 603         }
 604         printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
 605 #ifdef CONFIG_DEBUG_ERRORS
 606         __backtrace();
 607 #endif
 608 out:
 609         spin_unlock_irqrestore(&irq_controller_lock, flags);
 610 }
 611
 612 EXPORT_SYMBOL(free_irq);
 613
 614 /* Start the interrupt probing.  Unlike other architectures,
 615  * we don't return a mask of interrupts from probe_irq_on,
 616  * but return the number of interrupts enabled for the probe.
 617  * The interrupts which have been enabled for probing is
 618  * instead recorded in the irq_desc structure.
 619  */
 620 unsigned long probe_irq_on(void)
 621 {
 622         unsigned int i, irqs = 0;
 623         unsigned long delay;
 624
 625         /*
 626          * first snaffle up any unassigned but
 627          * probe-able interrupts
 628          */
 629         spin_lock_irq(&irq_controller_lock);
 630         for (i = 0; i < NR_IRQS; i++) {
 631                 if (!irq_desc[i].probe_ok || irq_desc[i].action)
 632                         continue;
 633
 634                 irq_desc[i].probing = 1;
 635                 irq_desc[i].triggered = 0;
 636                 if (irq_desc[i].chip->type)
 637                         irq_desc[i].chip->type(i, IRQT_PROBE);
 638                 irq_desc[i].chip->unmask(i);
 639                 irqs += 1;
 640         }
 641         spin_unlock_irq(&irq_controller_lock);
 642
 643         /*
 644          * wait for spurious interrupts to mask themselves out again
 645          */
 646         for (delay = jiffies + HZ/10; time_before(jiffies, delay); )
 647                 /* min 100ms delay */;
 648
 649         /*
 650          * now filter out any obviously spurious interrupts
 651          */
 652         spin_lock_irq(&irq_controller_lock);
 653         for (i = 0; i < NR_IRQS; i++) {
 654                 if (irq_desc[i].probing && irq_desc[i].triggered) {
 655                         irq_desc[i].probing = 0;
 656                         irqs -= 1;
 657                 }
 658         }
 659         spin_unlock_irq(&irq_controller_lock);
 660
 661         return irqs;
 662 }
 663
 664 EXPORT_SYMBOL(probe_irq_on);
 665
 666 /*
 667  * Possible return values:
 668  *  >= 0 - interrupt number
 669  *    -1 - no interrupt/many interrupts
 670  */
 671 int probe_irq_off(unsigned long irqs)
 672 {
 673         unsigned int i;
 674         int irq_found = NO_IRQ;
 675
 676         /*
 677          * look at the interrupts, and find exactly one
 678          * that we were probing has been triggered
 679          */
 680         spin_lock_irq(&irq_controller_lock);
 681         for (i = 0; i < NR_IRQS; i++) {
 682                 if (irq_desc[i].probing &&
 683                     irq_desc[i].triggered) {
 684                         if (irq_found != NO_IRQ) {
 685                                 irq_found = NO_IRQ;
 686                                 goto out;
 687                         }
 688                         irq_found = i;
 689                 }
 690         }
 691
 692         if (irq_found == -1)
 693                 irq_found = NO_IRQ;
 694 out:
 695         spin_unlock_irq(&irq_controller_lock);
 696
 697         return irq_found;
 698 }
 699
 700 EXPORT_SYMBOL(probe_irq_off);
 701
 702 void __init init_irq_proc(void)
 703 {
 704 }
 705
 706 void __init init_IRQ(void)
 707 {
 708         struct irqdesc *desc;
 709         extern void init_dma(void);
 710         int irq;
 711
 712         for (irq = 0, desc = irq_desc; irq < NR_IRQS; irq++, desc++)
 713                 *desc = bad_irq_desc;
 714
 715         arc_init_irq();
 716         init_dma();
 717 }