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