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   1 /*
   2  * linux/kernel/irq/handle.c
   3  *
   4  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
   5  * Copyright (C) 2005-2006, Thomas Gleixner, Russell King
   6  *
   7  * This file contains the core interrupt handling code.
   8  *
   9  * Detailed information is available in Documentation/DocBook/genericirq
  10  *
  11  */
  12
  13 #include <linux/irq.h>
  14 #include <linux/module.h>
  15 #include <linux/random.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/kernel_stat.h>
  18 #include <linux/rculist.h>
  19 #include <linux/hash.h>
  20
  21 #include "internals.h"
  22
  23 /*
  24  * lockdep: we want to handle all irq_desc locks as a single lock-class:
  25  */
  26 struct lock_class_key irq_desc_lock_class;
  27
  28 /**
  29  * handle_bad_irq - handle spurious and unhandled irqs
  30  * @irq:       the interrupt number
  31  * @desc:      description of the interrupt
  32  *
  33  * Handles spurious and unhandled IRQ's. It also prints a debugmessage.
  34  */
  35 void handle_bad_irq(unsigned int irq, struct irq_desc *desc)
  36 {
  37         print_irq_desc(irq, desc);
  38         kstat_incr_irqs_this_cpu(irq, desc);
  39         ack_bad_irq(irq);
  40 }
  41
  42 /*
  43  * Linux has a controller-independent interrupt architecture.
  44  * Every controller has a 'controller-template', that is used
  45  * by the main code to do the right thing. Each driver-visible
  46  * interrupt source is transparently wired to the appropriate
  47  * controller. Thus drivers need not be aware of the
  48  * interrupt-controller.
  49  *
  50  * The code is designed to be easily extended with new/different
  51  * interrupt controllers, without having to do assembly magic or
  52  * having to touch the generic code.
  53  *
  54  * Controller mappings for all interrupt sources:
  55  */
  56 int nr_irqs = NR_IRQS;
  57 EXPORT_SYMBOL_GPL(nr_irqs);
  58
  59 void __init __attribute__((weak)) arch_early_irq_init(void)
  60 {
  61 }
  62
  63 #ifdef CONFIG_SPARSE_IRQ
  64 static struct irq_desc irq_desc_init = {
  65         .irq        = -1,
  66         .status     = IRQ_DISABLED,
  67         .chip       = &no_irq_chip,
  68         .handle_irq = handle_bad_irq,
  69         .depth      = 1,
  70         .lock       = __SPIN_LOCK_UNLOCKED(irq_desc_init.lock),
  71 #ifdef CONFIG_SMP
  72         .affinity   = CPU_MASK_ALL
  73 #endif
  74 };
  75
  76 void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr)
  77 {
  78         unsigned long bytes;
  79         char *ptr;
  80         int node;
  81
  82         /* Compute how many bytes we need per irq and allocate them */
  83         bytes = nr * sizeof(unsigned int);
  84
  85         node = cpu_to_node(cpu);
  86         ptr = kzalloc_node(bytes, GFP_ATOMIC, node);
  87         printk(KERN_DEBUG "  alloc kstat_irqs on cpu %d node %d\n", cpu, node);
  88
  89         if (ptr)
  90                 desc->kstat_irqs = (unsigned int *)ptr;
  91 }
  92
  93 void __attribute__((weak)) arch_init_chip_data(struct irq_desc *desc, int cpu)
  94 {
  95 }
  96
  97 static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
  98 {
  99         memcpy(desc, &irq_desc_init, sizeof(struct irq_desc));
 100         desc->irq = irq;
 101 #ifdef CONFIG_SMP
 102         desc->cpu = cpu;
 103 #endif
 104         lockdep_set_class(&desc->lock, &irq_desc_lock_class);
 105         init_kstat_irqs(desc, cpu, nr_cpu_ids);
 106         if (!desc->kstat_irqs) {
 107                 printk(KERN_ERR "can not alloc kstat_irqs\n");
 108                 BUG_ON(1);
 109         }
 110         arch_init_chip_data(desc, cpu);
 111 }
 112
 113 /*
 114  * Protect the sparse_irqs:
 115  */
 116 DEFINE_SPINLOCK(sparse_irq_lock);
 117
 118 struct irq_desc *irq_desc_ptrs[NR_IRQS] __read_mostly;
 119
 120 static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_smp = {
 121         [0 ... NR_IRQS_LEGACY-1] = {
 122                 .irq        = -1,
 123                 .status     = IRQ_DISABLED,
 124                 .chip       = &no_irq_chip,
 125                 .handle_irq = handle_bad_irq,
 126                 .depth      = 1,
 127                 .lock       = __SPIN_LOCK_UNLOCKED(irq_desc_init.lock),
 128 #ifdef CONFIG_SMP
 129                 .affinity   = CPU_MASK_ALL
 130 #endif
 131         }
 132 };
 133
 134 /* FIXME: use bootmem alloc ...*/
 135 static unsigned int kstat_irqs_legacy[NR_IRQS_LEGACY][NR_CPUS];
 136
 137 void __init early_irq_init(void)
 138 {
 139         struct irq_desc *desc;
 140         int legacy_count;
 141         int i;
 142
 143         desc = irq_desc_legacy;
 144         legacy_count = ARRAY_SIZE(irq_desc_legacy);
 145
 146         for (i = 0; i < legacy_count; i++) {
 147                 desc[i].irq = i;
 148                 desc[i].kstat_irqs = kstat_irqs_legacy[i];
 149
 150                 irq_desc_ptrs[i] = desc + i;
 151         }
 152
 153         for (i = legacy_count; i < NR_IRQS; i++)
 154                 irq_desc_ptrs[i] = NULL;
 155
 156         arch_early_irq_init();
 157 }
 158
 159 struct irq_desc *irq_to_desc(unsigned int irq)
 160 {
 161         return (irq < NR_IRQS) ? irq_desc_ptrs[irq] : NULL;
 162 }
 163
 164 struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
 165 {
 166         struct irq_desc *desc;
 167         unsigned long flags;
 168         int node;
 169
 170         if (irq >= NR_IRQS) {
 171                 printk(KERN_WARNING "irq >= NR_IRQS in irq_to_desc_alloc: %d %d\n",
 172                                 irq, NR_IRQS);
 173                 WARN_ON(1);
 174                 return NULL;
 175         }
 176
 177         desc = irq_desc_ptrs[irq];
 178         if (desc)
 179                 return desc;
 180
 181         spin_lock_irqsave(&sparse_irq_lock, flags);
 182
 183         /* We have to check it to avoid races with another CPU */
 184         desc = irq_desc_ptrs[irq];
 185         if (desc)
 186                 goto out_unlock;
 187
 188         node = cpu_to_node(cpu);
 189         desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
 190         printk(KERN_DEBUG "  alloc irq_desc for %d on cpu %d node %d\n",
 191                  irq, cpu, node);
 192         if (!desc) {
 193                 printk(KERN_ERR "can not alloc irq_desc\n");
 194                 BUG_ON(1);
 195         }
 196         init_one_irq_desc(irq, desc, cpu);
 197
 198         irq_desc_ptrs[irq] = desc;
 199
 200 out_unlock:
 201         spin_unlock_irqrestore(&sparse_irq_lock, flags);
 202
 203         return desc;
 204 }
 205
 206 #else /* !CONFIG_SPARSE_IRQ */
 207
 208 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
 209         [0 ... NR_IRQS-1] = {
 210                 .status = IRQ_DISABLED,
 211                 .chip = &no_irq_chip,
 212                 .handle_irq = handle_bad_irq,
 213                 .depth = 1,
 214                 .lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
 215 #ifdef CONFIG_SMP
 216                 .affinity = CPU_MASK_ALL
 217 #endif
 218         }
 219 };
 220
 221 struct irq_desc *irq_to_desc(unsigned int irq)
 222 {
 223         return (irq < NR_IRQS) ? irq_desc + irq : NULL;
 224 }
 225
 226 struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
 227 {
 228         return irq_to_desc(irq);
 229 }
 230 #endif /* !CONFIG_SPARSE_IRQ */
 231
 232 /*
 233  * What should we do if we get a hw irq event on an illegal vector?
 234  * Each architecture has to answer this themself.
 235  */
 236 static void ack_bad(unsigned int irq)
 237 {
 238         struct irq_desc *desc = irq_to_desc(irq);
 239
 240         print_irq_desc(irq, desc);
 241         ack_bad_irq(irq);
 242 }
 243
 244 /*
 245  * NOP functions
 246  */
 247 static void noop(unsigned int irq)
 248 {
 249 }
 250
 251 static unsigned int noop_ret(unsigned int irq)
 252 {
 253         return 0;
 254 }
 255
 256 /*
 257  * Generic no controller implementation
 258  */
 259 struct irq_chip no_irq_chip = {
 260         .name           = "none",
 261         .startup        = noop_ret,
 262         .shutdown       = noop,
 263         .enable         = noop,
 264         .disable        = noop,
 265         .ack            = ack_bad,
 266         .end            = noop,
 267 };
 268
 269 /*
 270  * Generic dummy implementation which can be used for
 271  * real dumb interrupt sources
 272  */
 273 struct irq_chip dummy_irq_chip = {
 274         .name           = "dummy",
 275         .startup        = noop_ret,
 276         .shutdown       = noop,
 277         .enable         = noop,
 278         .disable        = noop,
 279         .ack            = noop,
 280         .mask           = noop,
 281         .unmask         = noop,
 282         .end            = noop,
 283 };
 284
 285 /*
 286  * Special, empty irq handler:
 287  */
 288 irqreturn_t no_action(int cpl, void *dev_id)
 289 {
 290         return IRQ_NONE;
 291 }
 292
 293 /**
 294  * handle_IRQ_event - irq action chain handler
 295  * @irq:        the interrupt number
 296  * @action:     the interrupt action chain for this irq
 297  *
 298  * Handles the action chain of an irq event
 299  */
 300 irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
 301 {
 302         irqreturn_t ret, retval = IRQ_NONE;
 303         unsigned int status = 0;
 304
 305         if (!(action->flags & IRQF_DISABLED))
 306                 local_irq_enable_in_hardirq();
 307
 308         do {
 309                 ret = action->handler(irq, action->dev_id);
 310                 if (ret == IRQ_HANDLED)
 311                         status |= action->flags;
 312                 retval |= ret;
 313                 action = action->next;
 314         } while (action);
 315
 316         if (status & IRQF_SAMPLE_RANDOM)
 317                 add_interrupt_randomness(irq);
 318         local_irq_disable();
 319
 320         return retval;
 321 }
 322
 323 #ifndef CONFIG_GENERIC_HARDIRQS_NO__DO_IRQ
 324 /**
 325  * __do_IRQ - original all in one highlevel IRQ handler
 326  * @irq:        the interrupt number
 327  *
 328  * __do_IRQ handles all normal device IRQ's (the special
 329  * SMP cross-CPU interrupts have their own specific
 330  * handlers).
 331  *
 332  * This is the original x86 implementation which is used for every
 333  * interrupt type.
 334  */
 335 unsigned int __do_IRQ(unsigned int irq)
 336 {
 337         struct irq_desc *desc = irq_to_desc(irq);
 338         struct irqaction *action;
 339         unsigned int status;
 340
 341         kstat_incr_irqs_this_cpu(irq, desc);
 342
 343         if (CHECK_IRQ_PER_CPU(desc->status)) {
 344                 irqreturn_t action_ret;
 345
 346                 /*
 347                  * No locking required for CPU-local interrupts:
 348                  */
 349                 if (desc->chip->ack) {
 350                         desc->chip->ack(irq);
 351                         /* get new one */
 352                         desc = irq_remap_to_desc(irq, desc);
 353                 }
 354                 if (likely(!(desc->status & IRQ_DISABLED))) {
 355                         action_ret = handle_IRQ_event(irq, desc->action);
 356                         if (!noirqdebug)
 357                                 note_interrupt(irq, desc, action_ret);
 358                 }
 359                 desc->chip->end(irq);
 360                 return 1;
 361         }
 362
 363         spin_lock(&desc->lock);
 364         if (desc->chip->ack) {
 365                 desc->chip->ack(irq);
 366                 desc = irq_remap_to_desc(irq, desc);
 367         }
 368         /*
 369          * REPLAY is when Linux resends an IRQ that was dropped earlier
 370          * WAITING is used by probe to mark irqs that are being tested
 371          */
 372         status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 373         status |= IRQ_PENDING; /* we _want_ to handle it */
 374
 375         /*
 376          * If the IRQ is disabled for whatever reason, we cannot
 377          * use the action we have.
 378          */
 379         action = NULL;
 380         if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
 381                 action = desc->action;
 382                 status &= ~IRQ_PENDING; /* we commit to handling */
 383                 status |= IRQ_INPROGRESS; /* we are handling it */
 384         }
 385         desc->status = status;
 386
 387         /*
 388          * If there is no IRQ handler or it was disabled, exit early.
 389          * Since we set PENDING, if another processor is handling
 390          * a different instance of this same irq, the other processor
 391          * will take care of it.
 392          */
 393         if (unlikely(!action))
 394                 goto out;
 395
 396         /*
 397          * Edge triggered interrupts need to remember
 398          * pending events.
 399          * This applies to any hw interrupts that allow a second
 400          * instance of the same irq to arrive while we are in do_IRQ
 401          * or in the handler. But the code here only handles the _second_
 402          * instance of the irq, not the third or fourth. So it is mostly
 403          * useful for irq hardware that does not mask cleanly in an
 404          * SMP environment.
 405          */
 406         for (;;) {
 407                 irqreturn_t action_ret;
 408
 409                 spin_unlock(&desc->lock);
 410
 411                 action_ret = handle_IRQ_event(irq, action);
 412                 if (!noirqdebug)
 413                         note_interrupt(irq, desc, action_ret);
 414
 415                 spin_lock(&desc->lock);
 416                 if (likely(!(desc->status & IRQ_PENDING)))
 417                         break;
 418                 desc->status &= ~IRQ_PENDING;
 419         }
 420         desc->status &= ~IRQ_INPROGRESS;
 421
 422 out:
 423         /*
 424          * The ->end() handler has to deal with interrupts which got
 425          * disabled while the handler was running.
 426          */
 427         desc->chip->end(irq);
 428         spin_unlock(&desc->lock);
 429
 430         return 1;
 431 }
 432 #endif
 433
 434 void early_init_irq_lock_class(void)
 435 {
 436         struct irq_desc *desc;
 437         int i;
 438
 439         for_each_irq_desc(i, desc) {
 440                 if (!desc)
 441                         continue;
 442
 443                 lockdep_set_class(&desc->lock, &irq_desc_lock_class);
 444         }
 445 }
 446
 447 #ifdef CONFIG_SPARSE_IRQ
 448 unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
 449 {
 450         struct irq_desc *desc = irq_to_desc(irq);
 451         return desc ? desc->kstat_irqs[cpu] : 0;
 452 }
 453 #endif
 454 EXPORT_SYMBOL(kstat_irqs_cpu);
 455