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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         int node;
  75         void *ptr;
  76
  77         node = cpu_to_node(cpu);
  78         ptr = kzalloc_node(nr * sizeof(*desc->kstat_irqs), GFP_ATOMIC, node);
  79
  80         /*
  81          * don't overwite if can not get new one
  82          * init_copy_kstat_irqs() could still use old one
  83          */
  84         if (ptr) {
  85                 printk(KERN_DEBUG "  alloc kstat_irqs on cpu %d node %d\n",
  86                          cpu, node);
  87                 desc->kstat_irqs = ptr;
  88         }
  89 }
  90
  91 static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
  92 {
  93         memcpy(desc, &irq_desc_init, sizeof(struct irq_desc));
  94
  95         spin_lock_init(&desc->lock);
  96         desc->irq = irq;
  97 #ifdef CONFIG_SMP
  98         desc->cpu = cpu;
  99 #endif
 100         lockdep_set_class(&desc->lock, &irq_desc_lock_class);
 101         init_kstat_irqs(desc, cpu, nr_cpu_ids);
 102         if (!desc->kstat_irqs) {
 103                 printk(KERN_ERR "can not alloc kstat_irqs\n");
 104                 BUG_ON(1);
 105         }
 106         arch_init_chip_data(desc, cpu);
 107 }
 108
 109 /*
 110  * Protect the sparse_irqs:
 111  */
 112 DEFINE_SPINLOCK(sparse_irq_lock);
 113
 114 struct irq_desc *irq_desc_ptrs[NR_IRQS] __read_mostly;
 115
 116 static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_smp = {
 117         [0 ... NR_IRQS_LEGACY-1] = {
 118                 .irq        = -1,
 119                 .status     = IRQ_DISABLED,
 120                 .chip       = &no_irq_chip,
 121                 .handle_irq = handle_bad_irq,
 122                 .depth      = 1,
 123                 .lock       = __SPIN_LOCK_UNLOCKED(irq_desc_init.lock),
 124 #ifdef CONFIG_SMP
 125                 .affinity   = CPU_MASK_ALL
 126 #endif
 127         }
 128 };
 129
 130 /* FIXME: use bootmem alloc ...*/
 131 static unsigned int kstat_irqs_legacy[NR_IRQS_LEGACY][NR_CPUS];
 132
 133 int __init early_irq_init(void)
 134 {
 135         struct irq_desc *desc;
 136         int legacy_count;
 137         int i;
 138
 139         desc = irq_desc_legacy;
 140         legacy_count = ARRAY_SIZE(irq_desc_legacy);
 141
 142         for (i = 0; i < legacy_count; i++) {
 143                 desc[i].irq = i;
 144                 desc[i].kstat_irqs = kstat_irqs_legacy[i];
 145                 lockdep_set_class(&desc[i].lock, &irq_desc_lock_class);
 146
 147                 irq_desc_ptrs[i] = desc + i;
 148         }
 149
 150         for (i = legacy_count; i < NR_IRQS; i++)
 151                 irq_desc_ptrs[i] = NULL;
 152
 153         return arch_early_irq_init();
 154 }
 155
 156 struct irq_desc *irq_to_desc(unsigned int irq)
 157 {
 158         return (irq < NR_IRQS) ? irq_desc_ptrs[irq] : NULL;
 159 }
 160
 161 struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
 162 {
 163         struct irq_desc *desc;
 164         unsigned long flags;
 165         int node;
 166
 167         if (irq >= NR_IRQS) {
 168                 printk(KERN_WARNING "irq >= NR_IRQS in irq_to_desc_alloc: %d %d\n",
 169                                 irq, NR_IRQS);
 170                 WARN_ON(1);
 171                 return NULL;
 172         }
 173
 174         desc = irq_desc_ptrs[irq];
 175         if (desc)
 176                 return desc;
 177
 178         spin_lock_irqsave(&sparse_irq_lock, flags);
 179
 180         /* We have to check it to avoid races with another CPU */
 181         desc = irq_desc_ptrs[irq];
 182         if (desc)
 183                 goto out_unlock;
 184
 185         node = cpu_to_node(cpu);
 186         desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
 187         printk(KERN_DEBUG "  alloc irq_desc for %d on cpu %d node %d\n",
 188                  irq, cpu, node);
 189         if (!desc) {
 190                 printk(KERN_ERR "can not alloc irq_desc\n");
 191                 BUG_ON(1);
 192         }
 193         init_one_irq_desc(irq, desc, cpu);
 194
 195         irq_desc_ptrs[irq] = desc;
 196
 197 out_unlock:
 198         spin_unlock_irqrestore(&sparse_irq_lock, flags);
 199
 200         return desc;
 201 }
 202
 203 #else /* !CONFIG_SPARSE_IRQ */
 204
 205 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
 206         [0 ... NR_IRQS-1] = {
 207                 .status = IRQ_DISABLED,
 208                 .chip = &no_irq_chip,
 209                 .handle_irq = handle_bad_irq,
 210                 .depth = 1,
 211                 .lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
 212 #ifdef CONFIG_SMP
 213                 .affinity = CPU_MASK_ALL
 214 #endif
 215         }
 216 };
 217
 218 static unsigned int kstat_irqs_all[NR_IRQS][NR_CPUS];
 219 int __init early_irq_init(void)
 220 {
 221         struct irq_desc *desc;
 222         int count;
 223         int i;
 224
 225         desc = irq_desc;
 226         count = ARRAY_SIZE(irq_desc);
 227
 228         for (i = 0; i < count; i++) {
 229                 desc[i].irq = i;
 230                 desc[i].kstat_irqs = kstat_irqs_all[i];
 231         }
 232
 233         return arch_early_irq_init();
 234 }
 235
 236 struct irq_desc *irq_to_desc(unsigned int irq)
 237 {
 238         return (irq < NR_IRQS) ? irq_desc + irq : NULL;
 239 }
 240
 241 struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
 242 {
 243         return irq_to_desc(irq);
 244 }
 245 #endif /* !CONFIG_SPARSE_IRQ */
 246
 247 void clear_kstat_irqs(struct irq_desc *desc)
 248 {
 249         memset(desc->kstat_irqs, 0, nr_cpu_ids * sizeof(*(desc->kstat_irqs)));
 250 }
 251
 252 /*
 253  * What should we do if we get a hw irq event on an illegal vector?
 254  * Each architecture has to answer this themself.
 255  */
 256 static void ack_bad(unsigned int irq)
 257 {
 258         struct irq_desc *desc = irq_to_desc(irq);
 259
 260         print_irq_desc(irq, desc);
 261         ack_bad_irq(irq);
 262 }
 263
 264 /*
 265  * NOP functions
 266  */
 267 static void noop(unsigned int irq)
 268 {
 269 }
 270
 271 static unsigned int noop_ret(unsigned int irq)
 272 {
 273         return 0;
 274 }
 275
 276 /*
 277  * Generic no controller implementation
 278  */
 279 struct irq_chip no_irq_chip = {
 280         .name           = "none",
 281         .startup        = noop_ret,
 282         .shutdown       = noop,
 283         .enable         = noop,
 284         .disable        = noop,
 285         .ack            = ack_bad,
 286         .end            = noop,
 287 };
 288
 289 /*
 290  * Generic dummy implementation which can be used for
 291  * real dumb interrupt sources
 292  */
 293 struct irq_chip dummy_irq_chip = {
 294         .name           = "dummy",
 295         .startup        = noop_ret,
 296         .shutdown       = noop,
 297         .enable         = noop,
 298         .disable        = noop,
 299         .ack            = noop,
 300         .mask           = noop,
 301         .unmask         = noop,
 302         .end            = noop,
 303 };
 304
 305 /*
 306  * Special, empty irq handler:
 307  */
 308 irqreturn_t no_action(int cpl, void *dev_id)
 309 {
 310         return IRQ_NONE;
 311 }
 312
 313 /**
 314  * handle_IRQ_event - irq action chain handler
 315  * @irq:        the interrupt number
 316  * @action:     the interrupt action chain for this irq
 317  *
 318  * Handles the action chain of an irq event
 319  */
 320 irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
 321 {
 322         irqreturn_t ret, retval = IRQ_NONE;
 323         unsigned int status = 0;
 324
 325         if (!(action->flags & IRQF_DISABLED))
 326                 local_irq_enable_in_hardirq();
 327
 328         do {
 329                 ret = action->handler(irq, action->dev_id);
 330                 if (ret == IRQ_HANDLED)
 331                         status |= action->flags;
 332                 retval |= ret;
 333                 action = action->next;
 334         } while (action);
 335
 336         if (status & IRQF_SAMPLE_RANDOM)
 337                 add_interrupt_randomness(irq);
 338         local_irq_disable();
 339
 340         return retval;
 341 }
 342
 343 #ifndef CONFIG_GENERIC_HARDIRQS_NO__DO_IRQ
 344 /**
 345  * __do_IRQ - original all in one highlevel IRQ handler
 346  * @irq:        the interrupt number
 347  *
 348  * __do_IRQ handles all normal device IRQ's (the special
 349  * SMP cross-CPU interrupts have their own specific
 350  * handlers).
 351  *
 352  * This is the original x86 implementation which is used for every
 353  * interrupt type.
 354  */
 355 unsigned int __do_IRQ(unsigned int irq)
 356 {
 357         struct irq_desc *desc = irq_to_desc(irq);
 358         struct irqaction *action;
 359         unsigned int status;
 360
 361         kstat_incr_irqs_this_cpu(irq, desc);
 362
 363         if (CHECK_IRQ_PER_CPU(desc->status)) {
 364                 irqreturn_t action_ret;
 365
 366                 /*
 367                  * No locking required for CPU-local interrupts:
 368                  */
 369                 if (desc->chip->ack) {
 370                         desc->chip->ack(irq);
 371                         /* get new one */
 372                         desc = irq_remap_to_desc(irq, desc);
 373                 }
 374                 if (likely(!(desc->status & IRQ_DISABLED))) {
 375                         action_ret = handle_IRQ_event(irq, desc->action);
 376                         if (!noirqdebug)
 377                                 note_interrupt(irq, desc, action_ret);
 378                 }
 379                 desc->chip->end(irq);
 380                 return 1;
 381         }
 382
 383         spin_lock(&desc->lock);
 384         if (desc->chip->ack) {
 385                 desc->chip->ack(irq);
 386                 desc = irq_remap_to_desc(irq, desc);
 387         }
 388         /*
 389          * REPLAY is when Linux resends an IRQ that was dropped earlier
 390          * WAITING is used by probe to mark irqs that are being tested
 391          */
 392         status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 393         status |= IRQ_PENDING; /* we _want_ to handle it */
 394
 395         /*
 396          * If the IRQ is disabled for whatever reason, we cannot
 397          * use the action we have.
 398          */
 399         action = NULL;
 400         if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
 401                 action = desc->action;
 402                 status &= ~IRQ_PENDING; /* we commit to handling */
 403                 status |= IRQ_INPROGRESS; /* we are handling it */
 404         }
 405         desc->status = status;
 406
 407         /*
 408          * If there is no IRQ handler or it was disabled, exit early.
 409          * Since we set PENDING, if another processor is handling
 410          * a different instance of this same irq, the other processor
 411          * will take care of it.
 412          */
 413         if (unlikely(!action))
 414                 goto out;
 415
 416         /*
 417          * Edge triggered interrupts need to remember
 418          * pending events.
 419          * This applies to any hw interrupts that allow a second
 420          * instance of the same irq to arrive while we are in do_IRQ
 421          * or in the handler. But the code here only handles the _second_
 422          * instance of the irq, not the third or fourth. So it is mostly
 423          * useful for irq hardware that does not mask cleanly in an
 424          * SMP environment.
 425          */
 426         for (;;) {
 427                 irqreturn_t action_ret;
 428
 429                 spin_unlock(&desc->lock);
 430
 431                 action_ret = handle_IRQ_event(irq, action);
 432                 if (!noirqdebug)
 433                         note_interrupt(irq, desc, action_ret);
 434
 435                 spin_lock(&desc->lock);
 436                 if (likely(!(desc->status & IRQ_PENDING)))
 437                         break;
 438                 desc->status &= ~IRQ_PENDING;
 439         }
 440         desc->status &= ~IRQ_INPROGRESS;
 441
 442 out:
 443         /*
 444          * The ->end() handler has to deal with interrupts which got
 445          * disabled while the handler was running.
 446          */
 447         desc->chip->end(irq);
 448         spin_unlock(&desc->lock);
 449
 450         return 1;
 451 }
 452 #endif
 453
 454 void early_init_irq_lock_class(void)
 455 {
 456         struct irq_desc *desc;
 457         int i;
 458
 459         for_each_irq_desc(i, desc) {
 460                 lockdep_set_class(&desc->lock, &irq_desc_lock_class);
 461         }
 462 }
 463
 464 unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
 465 {
 466         struct irq_desc *desc = irq_to_desc(irq);
 467         return desc ? desc->kstat_irqs[cpu] : 0;
 468 }
 469 EXPORT_SYMBOL(kstat_irqs_cpu);
 470