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/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 #include <linux/vs_context.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 & IRQF_DISABLED))
 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 & IRQF_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         struct vx_info_save vxis;
 336
 337         /*
 338          * Some hardware gives randomly wrong interrupts.  Rather
 339          * than crashing, do something sensible.
 340          */
 341         if (irq >= NR_IRQS)
 342                 desc = &bad_irq_desc;
 343
 344         irq_enter();
 345         spin_lock(&irq_controller_lock);
 346         __enter_vx_admin(&vxis);
 347         desc->handle(irq, desc, regs);
 348         __leave_vx_admin(&vxis);
 349         spin_unlock(&irq_controller_lock);
 350         irq_exit();
 351 }
 352
 353 void __set_irq_handler(unsigned int irq, irq_handler_t handle, int is_chained)
 354 {
 355         struct irqdesc *desc;
 356         unsigned long flags;
 357
 358         if (irq >= NR_IRQS) {
 359                 printk(KERN_ERR "Trying to install handler for IRQ%d\n", irq);
 360                 return;
 361         }
 362
 363         if (handle == NULL)
 364                 handle = do_bad_IRQ;
 365
 366         desc = irq_desc + irq;
 367
 368         if (is_chained && desc->chip == &bad_chip)
 369                 printk(KERN_WARNING "Trying to install chained handler for IRQ%d\n", irq);
 370
 371         spin_lock_irqsave(&irq_controller_lock, flags);
 372         if (handle == do_bad_IRQ) {
 373                 desc->chip->mask(irq);
 374                 desc->chip->ack(irq);
 375                 desc->depth = 1;
 376                 desc->enabled = 0;
 377         }
 378         desc->handle = handle;
 379         if (handle != do_bad_IRQ && is_chained) {
 380                 desc->valid = 0;
 381                 desc->probe_ok = 0;
 382                 desc->depth = 0;
 383                 desc->chip->unmask(irq);
 384         }
 385         spin_unlock_irqrestore(&irq_controller_lock, flags);
 386 }
 387
 388 void set_irq_chip(unsigned int irq, struct irqchip *chip)
 389 {
 390         struct irqdesc *desc;
 391         unsigned long flags;
 392
 393         if (irq >= NR_IRQS) {
 394                 printk(KERN_ERR "Trying to install chip for IRQ%d\n", irq);
 395                 return;
 396         }
 397
 398         if (chip == NULL)
 399                 chip = &bad_chip;
 400
 401         desc = irq_desc + irq;
 402         spin_lock_irqsave(&irq_controller_lock, flags);
 403         desc->chip = chip;
 404         spin_unlock_irqrestore(&irq_controller_lock, flags);
 405 }
 406
 407 int set_irq_type(unsigned int irq, unsigned int type)
 408 {
 409         struct irqdesc *desc;
 410         unsigned long flags;
 411         int ret = -ENXIO;
 412
 413         if (irq >= NR_IRQS) {
 414                 printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
 415                 return -ENODEV;
 416         }
 417
 418         desc = irq_desc + irq;
 419         if (desc->chip->type) {
 420                 spin_lock_irqsave(&irq_controller_lock, flags);
 421                 ret = desc->chip->type(irq, type);
 422                 spin_unlock_irqrestore(&irq_controller_lock, flags);
 423         }
 424
 425         return ret;
 426 }
 427
 428 void set_irq_flags(unsigned int irq, unsigned int iflags)
 429 {
 430         struct irqdesc *desc;
 431         unsigned long flags;
 432
 433         if (irq >= NR_IRQS) {
 434                 printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
 435                 return;
 436         }
 437
 438         desc = irq_desc + irq;
 439         spin_lock_irqsave(&irq_controller_lock, flags);
 440         desc->valid = (iflags & IRQF_VALID) != 0;
 441         desc->probe_ok = (iflags & IRQF_PROBE) != 0;
 442         desc->noautoenable = (iflags & IRQF_NOAUTOEN) != 0;
 443         spin_unlock_irqrestore(&irq_controller_lock, flags);
 444 }
 445
 446 int setup_irq(unsigned int irq, struct irqaction *new)
 447 {
 448         int shared = 0;
 449         struct irqaction *old, **p;
 450         unsigned long flags;
 451         struct irqdesc *desc;
 452
 453         /*
 454          * Some drivers like serial.c use request_irq() heavily,
 455          * so we have to be careful not to interfere with a
 456          * running system.
 457          */
 458         if (new->flags & IRQF_SAMPLE_RANDOM) {
 459                 /*
 460                  * This function might sleep, we want to call it first,
 461                  * outside of the atomic block.
 462                  * Yes, this might clear the entropy pool if the wrong
 463                  * driver is attempted to be loaded, without actually
 464                  * installing a new handler, but is this really a problem,
 465                  * only the sysadmin is able to do this.
 466                  */
 467                 rand_initialize_irq(irq);
 468         }
 469
 470         /*
 471          * The following block of code has to be executed atomically
 472          */
 473         desc = irq_desc + irq;
 474         spin_lock_irqsave(&irq_controller_lock, flags);
 475         p = &desc->action;
 476         if ((old = *p) != NULL) {
 477                 /* Can't share interrupts unless both agree to */
 478                 if (!(old->flags & new->flags & IRQF_SHARED)) {
 479                         spin_unlock_irqrestore(&irq_controller_lock, flags);
 480                         return -EBUSY;
 481                 }
 482
 483                 /* add new interrupt at end of irq queue */
 484                 do {
 485                         p = &old->next;
 486                         old = *p;
 487                 } while (old);
 488                 shared = 1;
 489         }
 490
 491         *p = new;
 492
 493         if (!shared) {
 494                 desc->probing = 0;
 495                 desc->running = 0;
 496                 desc->pending = 0;
 497                 desc->depth = 1;
 498                 if (!desc->noautoenable) {
 499                         desc->depth = 0;
 500                         desc->enabled = 1;
 501                         desc->chip->unmask(irq);
 502                 }
 503         }
 504
 505         spin_unlock_irqrestore(&irq_controller_lock, flags);
 506         return 0;
 507 }
 508
 509 /**
 510  *      request_irq - allocate an interrupt line
 511  *      @irq: Interrupt line to allocate
 512  *      @handler: Function to be called when the IRQ occurs
 513  *      @irqflags: Interrupt type flags
 514  *      @devname: An ascii name for the claiming device
 515  *      @dev_id: A cookie passed back to the handler function
 516  *
 517  *      This call allocates interrupt resources and enables the
 518  *      interrupt line and IRQ handling. From the point this
 519  *      call is made your handler function may be invoked. Since
 520  *      your handler function must clear any interrupt the board
 521  *      raises, you must take care both to initialise your hardware
 522  *      and to set up the interrupt handler in the right order.
 523  *
 524  *      Dev_id must be globally unique. Normally the address of the
 525  *      device data structure is used as the cookie. Since the handler
 526  *      receives this value it makes sense to use it.
 527  *
 528  *      If your interrupt is shared you must pass a non NULL dev_id
 529  *      as this is required when freeing the interrupt.
 530  *
 531  *      Flags:
 532  *
 533  *      IRQF_SHARED             Interrupt is shared
 534  *
 535  *      IRQF_DISABLED   Disable local interrupts while processing
 536  *
 537  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
 538  *
 539  */
 540
 541 //FIXME - handler used to return void - whats the significance of the change?
 542 int request_irq(unsigned int irq, irqreturn_t (*handler)(int, void *, struct pt_regs *),
 543                  unsigned long irq_flags, const char * devname, void *dev_id)
 544 {
 545         unsigned long retval;
 546         struct irqaction *action;
 547
 548         if (irq >= NR_IRQS || !irq_desc[irq].valid || !handler ||
 549             (irq_flags & IRQF_SHARED && !dev_id))
 550                 return -EINVAL;
 551
 552         action = (struct irqaction *)kmalloc(sizeof(struct irqaction), GFP_KERNEL);
 553         if (!action)
 554                 return -ENOMEM;
 555
 556         action->handler = handler;
 557         action->flags = irq_flags;
 558         cpus_clear(action->mask);
 559         action->name = devname;
 560         action->next = NULL;
 561         action->dev_id = dev_id;
 562
 563         retval = setup_irq(irq, action);
 564
 565         if (retval)
 566                 kfree(action);
 567         return retval;
 568 }
 569
 570 EXPORT_SYMBOL(request_irq);
 571
 572 /**
 573  *      free_irq - free an interrupt
 574  *      @irq: Interrupt line to free
 575  *      @dev_id: Device identity to free
 576  *
 577  *      Remove an interrupt handler. The handler is removed and if the
 578  *      interrupt line is no longer in use by any driver it is disabled.
 579  *      On a shared IRQ the caller must ensure the interrupt is disabled
 580  *      on the card it drives before calling this function.
 581  *
 582  *      This function may be called from interrupt context.
 583  */
 584 void free_irq(unsigned int irq, void *dev_id)
 585 {
 586         struct irqaction * action, **p;
 587         unsigned long flags;
 588
 589         if (irq >= NR_IRQS || !irq_desc[irq].valid) {
 590                 printk(KERN_ERR "Trying to free IRQ%d\n",irq);
 591 #ifdef CONFIG_DEBUG_ERRORS
 592                 __backtrace();
 593 #endif
 594                 return;
 595         }
 596
 597         spin_lock_irqsave(&irq_controller_lock, flags);
 598         for (p = &irq_desc[irq].action; (action = *p) != NULL; p = &action->next) {
 599                 if (action->dev_id != dev_id)
 600                         continue;
 601
 602                 /* Found it - now free it */
 603                 *p = action->next;
 604                 kfree(action);
 605                 goto out;
 606         }
 607         printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
 608 #ifdef CONFIG_DEBUG_ERRORS
 609         __backtrace();
 610 #endif
 611 out:
 612         spin_unlock_irqrestore(&irq_controller_lock, flags);
 613 }
 614
 615 EXPORT_SYMBOL(free_irq);
 616
 617 /* Start the interrupt probing.  Unlike other architectures,
 618  * we don't return a mask of interrupts from probe_irq_on,
 619  * but return the number of interrupts enabled for the probe.
 620  * The interrupts which have been enabled for probing is
 621  * instead recorded in the irq_desc structure.
 622  */
 623 unsigned long probe_irq_on(void)
 624 {
 625         unsigned int i, irqs = 0;
 626         unsigned long delay;
 627
 628         /*
 629          * first snaffle up any unassigned but
 630          * probe-able interrupts
 631          */
 632         spin_lock_irq(&irq_controller_lock);
 633         for (i = 0; i < NR_IRQS; i++) {
 634                 if (!irq_desc[i].probe_ok || irq_desc[i].action)
 635                         continue;
 636
 637                 irq_desc[i].probing = 1;
 638                 irq_desc[i].triggered = 0;
 639                 if (irq_desc[i].chip->type)
 640                         irq_desc[i].chip->type(i, IRQT_PROBE);
 641                 irq_desc[i].chip->unmask(i);
 642                 irqs += 1;
 643         }
 644         spin_unlock_irq(&irq_controller_lock);
 645
 646         /*
 647          * wait for spurious interrupts to mask themselves out again
 648          */
 649         for (delay = jiffies + HZ/10; time_before(jiffies, delay); )
 650                 /* min 100ms delay */;
 651
 652         /*
 653          * now filter out any obviously spurious interrupts
 654          */
 655         spin_lock_irq(&irq_controller_lock);
 656         for (i = 0; i < NR_IRQS; i++) {
 657                 if (irq_desc[i].probing && irq_desc[i].triggered) {
 658                         irq_desc[i].probing = 0;
 659                         irqs -= 1;
 660                 }
 661         }
 662         spin_unlock_irq(&irq_controller_lock);
 663
 664         return irqs;
 665 }
 666
 667 EXPORT_SYMBOL(probe_irq_on);
 668
 669 /*
 670  * Possible return values:
 671  *  >= 0 - interrupt number
 672  *    -1 - no interrupt/many interrupts
 673  */
 674 int probe_irq_off(unsigned long irqs)
 675 {
 676         unsigned int i;
 677         int irq_found = NO_IRQ;
 678
 679         /*
 680          * look at the interrupts, and find exactly one
 681          * that we were probing has been triggered
 682          */
 683         spin_lock_irq(&irq_controller_lock);
 684         for (i = 0; i < NR_IRQS; i++) {
 685                 if (irq_desc[i].probing &&
 686                     irq_desc[i].triggered) {
 687                         if (irq_found != NO_IRQ) {
 688                                 irq_found = NO_IRQ;
 689                                 goto out;
 690                         }
 691                         irq_found = i;
 692                 }
 693         }
 694
 695         if (irq_found == -1)
 696                 irq_found = NO_IRQ;
 697 out:
 698         spin_unlock_irq(&irq_controller_lock);
 699
 700         return irq_found;
 701 }
 702
 703 EXPORT_SYMBOL(probe_irq_off);
 704
 705 void __init init_irq_proc(void)
 706 {
 707 }
 708
 709 void __init init_IRQ(void)
 710 {
 711         struct irqdesc *desc;
 712         extern void init_dma(void);
 713         int irq;
 714
 715         for (irq = 0, desc = irq_desc; irq < NR_IRQS; irq++, desc++)
 716                 *desc = bad_irq_desc;
 717
 718         arc_init_irq();
 719         init_dma();
 720 }