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