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