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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 };
  68
  69 void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr)
  70 {
  71         unsigned long bytes;
  72         char *ptr;
  73         int node;
  74
  75         /* Compute how many bytes we need per irq and allocate them */
  76         bytes = nr * sizeof(unsigned int);
  77
  78         node = cpu_to_node(cpu);
  79         ptr = kzalloc_node(bytes, GFP_ATOMIC, node);
  80         printk(KERN_DEBUG "  alloc kstat_irqs on cpu %d node %d\n", cpu, node);
  81
  82         if (ptr)
  83                 desc->kstat_irqs = (unsigned int *)ptr;
  84 }
  85
  86 static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
  87 {
  88         memcpy(desc, &irq_desc_init, sizeof(struct irq_desc));
  89
  90         spin_lock_init(&desc->lock);
  91         desc->irq = irq;
  92 #ifdef CONFIG_SMP
  93         desc->cpu = cpu;
  94 #endif
  95         lockdep_set_class(&desc->lock, &irq_desc_lock_class);
  96         init_kstat_irqs(desc, cpu, nr_cpu_ids);
  97         if (!desc->kstat_irqs) {
  98                 printk(KERN_ERR "can not alloc kstat_irqs\n");
  99                 BUG_ON(1);
 100         }
 101         if (!init_alloc_desc_masks(desc, cpu, false)) {
 102                 printk(KERN_ERR "can not alloc irq_desc cpumasks\n");
 103                 BUG_ON(1);
 104         }
 105         arch_init_chip_data(desc, cpu);
 106 }
 107
 108 /*
 109  * Protect the sparse_irqs:
 110  */
 111 DEFINE_SPINLOCK(sparse_irq_lock);
 112
 113 struct irq_desc *irq_desc_ptrs[NR_IRQS] __read_mostly;
 114
 115 static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_smp = {
 116         [0 ... NR_IRQS_LEGACY-1] = {
 117                 .irq        = -1,
 118                 .status     = IRQ_DISABLED,
 119                 .chip       = &no_irq_chip,
 120                 .handle_irq = handle_bad_irq,
 121                 .depth      = 1,
 122                 .lock       = __SPIN_LOCK_UNLOCKED(irq_desc_init.lock),
 123         }
 124 };
 125
 126 /* FIXME: use bootmem alloc ...*/
 127 static unsigned int kstat_irqs_legacy[NR_IRQS_LEGACY][NR_CPUS];
 128
 129 int __init early_irq_init(void)
 130 {
 131         struct irq_desc *desc;
 132         int legacy_count;
 133         int i;
 134
 135         printk(KERN_INFO "NR_IRQS:%d nr_irqs:%d\n", NR_IRQS, nr_irqs);
 136
 137         desc = irq_desc_legacy;
 138         legacy_count = ARRAY_SIZE(irq_desc_legacy);
 139
 140         for (i = 0; i < legacy_count; i++) {
 141                 desc[i].irq = i;
 142                 desc[i].kstat_irqs = kstat_irqs_legacy[i];
 143                 lockdep_set_class(&desc[i].lock, &irq_desc_lock_class);
 144                 init_alloc_desc_masks(&desc[i], 0, true);
 145                 irq_desc_ptrs[i] = desc + i;
 146         }
 147
 148         for (i = legacy_count; i < nr_irqs; i++)
 149                 irq_desc_ptrs[i] = NULL;
 150
 151         return arch_early_irq_init();
 152 }
 153
 154 struct irq_desc *irq_to_desc(unsigned int irq)
 155 {
 156         return (irq < nr_irqs) ? irq_desc_ptrs[irq] : NULL;
 157 }
 158
 159 struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
 160 {
 161         struct irq_desc *desc;
 162         unsigned long flags;
 163         int node;
 164
 165         if (irq >= nr_irqs) {
 166                 WARN(1, "irq (%d) >= nr_irqs (%d) in irq_to_desc_alloc\n",
 167                         irq, nr_irqs);
 168                 return NULL;
 169         }
 170
 171         desc = irq_desc_ptrs[irq];
 172         if (desc)
 173                 return desc;
 174
 175         spin_lock_irqsave(&sparse_irq_lock, flags);
 176
 177         /* We have to check it to avoid races with another CPU */
 178         desc = irq_desc_ptrs[irq];
 179         if (desc)
 180                 goto out_unlock;
 181
 182         node = cpu_to_node(cpu);
 183         desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
 184         printk(KERN_DEBUG "  alloc irq_desc for %d on cpu %d node %d\n",
 185                  irq, cpu, node);
 186         if (!desc) {
 187                 printk(KERN_ERR "can not alloc irq_desc\n");
 188                 BUG_ON(1);
 189         }
 190         init_one_irq_desc(irq, desc, cpu);
 191
 192         irq_desc_ptrs[irq] = desc;
 193
 194 out_unlock:
 195         spin_unlock_irqrestore(&sparse_irq_lock, flags);
 196
 197         return desc;
 198 }
 199
 200 #else /* !CONFIG_SPARSE_IRQ */
 201
 202 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
 203         [0 ... NR_IRQS-1] = {
 204                 .status = IRQ_DISABLED,
 205                 .chip = &no_irq_chip,
 206                 .handle_irq = handle_bad_irq,
 207                 .depth = 1,
 208                 .lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
 209         }
 210 };
 211
 212 int __init early_irq_init(void)
 213 {
 214         struct irq_desc *desc;
 215         int count;
 216         int i;
 217
 218         printk(KERN_INFO "NR_IRQS:%d\n", NR_IRQS);
 219
 220         desc = irq_desc;
 221         count = ARRAY_SIZE(irq_desc);
 222
 223         for (i = 0; i < count; i++) {
 224                 desc[i].irq = i;
 225                 init_alloc_desc_masks(&desc[i], 0, true);
 226         }
 227         return arch_early_irq_init();
 228 }
 229
 230 struct irq_desc *irq_to_desc(unsigned int irq)
 231 {
 232         return (irq < NR_IRQS) ? irq_desc + irq : NULL;
 233 }
 234
 235 struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
 236 {
 237         return irq_to_desc(irq);
 238 }
 239 #endif /* !CONFIG_SPARSE_IRQ */
 240
 241 /*
 242  * What should we do if we get a hw irq event on an illegal vector?
 243  * Each architecture has to answer this themself.
 244  */
 245 static void ack_bad(unsigned int irq)
 246 {
 247         struct irq_desc *desc = irq_to_desc(irq);
 248
 249         print_irq_desc(irq, desc);
 250         ack_bad_irq(irq);
 251 }
 252
 253 /*
 254  * NOP functions
 255  */
 256 static void noop(unsigned int irq)
 257 {
 258 }
 259
 260 static unsigned int noop_ret(unsigned int irq)
 261 {
 262         return 0;
 263 }
 264
 265 /*
 266  * Generic no controller implementation
 267  */
 268 struct irq_chip no_irq_chip = {
 269         .name           = "none",
 270         .startup        = noop_ret,
 271         .shutdown       = noop,
 272         .enable         = noop,
 273         .disable        = noop,
 274         .ack            = ack_bad,
 275         .end            = noop,
 276 };
 277
 278 /*
 279  * Generic dummy implementation which can be used for
 280  * real dumb interrupt sources
 281  */
 282 struct irq_chip dummy_irq_chip = {
 283         .name           = "dummy",
 284         .startup        = noop_ret,
 285         .shutdown       = noop,
 286         .enable         = noop,
 287         .disable        = noop,
 288         .ack            = noop,
 289         .mask           = noop,
 290         .unmask         = noop,
 291         .end            = noop,
 292 };
 293
 294 /*
 295  * Special, empty irq handler:
 296  */
 297 irqreturn_t no_action(int cpl, void *dev_id)
 298 {
 299         return IRQ_NONE;
 300 }
 301
 302 /**
 303  * handle_IRQ_event - irq action chain handler
 304  * @irq:        the interrupt number
 305  * @action:     the interrupt action chain for this irq
 306  *
 307  * Handles the action chain of an irq event
 308  */
 309 irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
 310 {
 311         irqreturn_t ret, retval = IRQ_NONE;
 312         unsigned int status = 0;
 313
 314         if (!(action->flags & IRQF_DISABLED))
 315                 local_irq_enable_in_hardirq();
 316
 317         do {
 318                 ret = action->handler(irq, action->dev_id);
 319                 if (ret == IRQ_HANDLED)
 320                         status |= action->flags;
 321                 retval |= ret;
 322                 action = action->next;
 323         } while (action);
 324
 325         if (status & IRQF_SAMPLE_RANDOM)
 326                 add_interrupt_randomness(irq);
 327         local_irq_disable();
 328
 329         return retval;
 330 }
 331
 332 #ifndef CONFIG_GENERIC_HARDIRQS_NO__DO_IRQ
 333 /**
 334  * __do_IRQ - original all in one highlevel IRQ handler
 335  * @irq:        the interrupt number
 336  *
 337  * __do_IRQ handles all normal device IRQ's (the special
 338  * SMP cross-CPU interrupts have their own specific
 339  * handlers).
 340  *
 341  * This is the original x86 implementation which is used for every
 342  * interrupt type.
 343  */
 344 unsigned int __do_IRQ(unsigned int irq)
 345 {
 346         struct irq_desc *desc = irq_to_desc(irq);
 347         struct irqaction *action;
 348         unsigned int status;
 349
 350         kstat_incr_irqs_this_cpu(irq, desc);
 351
 352         if (CHECK_IRQ_PER_CPU(desc->status)) {
 353                 irqreturn_t action_ret;
 354
 355                 /*
 356                  * No locking required for CPU-local interrupts:
 357                  */
 358                 if (desc->chip->ack) {
 359                         desc->chip->ack(irq);
 360                         /* get new one */
 361                         desc = irq_remap_to_desc(irq, desc);
 362                 }
 363                 if (likely(!(desc->status & IRQ_DISABLED))) {
 364                         action_ret = handle_IRQ_event(irq, desc->action);
 365                         if (!noirqdebug)
 366                                 note_interrupt(irq, desc, action_ret);
 367                 }
 368                 desc->chip->end(irq);
 369                 return 1;
 370         }
 371
 372         spin_lock(&desc->lock);
 373         if (desc->chip->ack) {
 374                 desc->chip->ack(irq);
 375                 desc = irq_remap_to_desc(irq, desc);
 376         }
 377         /*
 378          * REPLAY is when Linux resends an IRQ that was dropped earlier
 379          * WAITING is used by probe to mark irqs that are being tested
 380          */
 381         status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 382         status |= IRQ_PENDING; /* we _want_ to handle it */
 383
 384         /*
 385          * If the IRQ is disabled for whatever reason, we cannot
 386          * use the action we have.
 387          */
 388         action = NULL;
 389         if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
 390                 action = desc->action;
 391                 status &= ~IRQ_PENDING; /* we commit to handling */
 392                 status |= IRQ_INPROGRESS; /* we are handling it */
 393         }
 394         desc->status = status;
 395
 396         /*
 397          * If there is no IRQ handler or it was disabled, exit early.
 398          * Since we set PENDING, if another processor is handling
 399          * a different instance of this same irq, the other processor
 400          * will take care of it.
 401          */
 402         if (unlikely(!action))
 403                 goto out;
 404
 405         /*
 406          * Edge triggered interrupts need to remember
 407          * pending events.
 408          * This applies to any hw interrupts that allow a second
 409          * instance of the same irq to arrive while we are in do_IRQ
 410          * or in the handler. But the code here only handles the _second_
 411          * instance of the irq, not the third or fourth. So it is mostly
 412          * useful for irq hardware that does not mask cleanly in an
 413          * SMP environment.
 414          */
 415         for (;;) {
 416                 irqreturn_t action_ret;
 417
 418                 spin_unlock(&desc->lock);
 419
 420                 action_ret = handle_IRQ_event(irq, action);
 421                 if (!noirqdebug)
 422                         note_interrupt(irq, desc, action_ret);
 423
 424                 spin_lock(&desc->lock);
 425                 if (likely(!(desc->status & IRQ_PENDING)))
 426                         break;
 427                 desc->status &= ~IRQ_PENDING;
 428         }
 429         desc->status &= ~IRQ_INPROGRESS;
 430
 431 out:
 432         /*
 433          * The ->end() handler has to deal with interrupts which got
 434          * disabled while the handler was running.
 435          */
 436         desc->chip->end(irq);
 437         spin_unlock(&desc->lock);
 438
 439         return 1;
 440 }
 441 #endif
 442
 443 void early_init_irq_lock_class(void)
 444 {
 445         struct irq_desc *desc;
 446         int i;
 447
 448         for_each_irq_desc(i, desc) {
 449                 lockdep_set_class(&desc->lock, &irq_desc_lock_class);
 450         }
 451 }
 452
 453 #ifdef CONFIG_SPARSE_IRQ
 454 unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
 455 {
 456         struct irq_desc *desc = irq_to_desc(irq);
 457         return desc ? desc->kstat_irqs[cpu] : 0;
 458 }
 459 #endif
 460 EXPORT_SYMBOL(kstat_irqs_cpu);
 461