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irq.c

/*
 *  Derived from arch/i386/kernel/irq.c
 *    Copyright (C) 1992 Linus Torvalds
 *  Adapted from arch/i386 by Gary Thomas
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *  Updated and modified by Cort Dougan <cort@fsmlabs.com>
 *    Copyright (C) 1996-2001 Cort Dougan
 *  Adapted for Power Macintosh by Paul Mackerras
 *    Copyright (C) 1996 Paul Mackerras (paulus@cs.anu.edu.au)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 * This file contains the code used by various IRQ handling routines:
 * asking for different IRQ's should be done through these routines
 * instead of just grabbing them. Thus setups with different IRQ numbers
 * shouldn't result in any weird surprises, and installing new handlers
 * should be easier.
 *
 * The MPC8xx has an interrupt mask in the SIU.  If a bit is set, the
 * interrupt is _enabled_.  As expected, IRQ0 is bit 0 in the 32-bit
 * mask register (of which only 16 are defined), hence the weird shifting
 * and complement of the cached_irq_mask.  I want to be able to stuff
 * this right into the SIU SMASK register.
 * Many of the prep/chrp functions are conditional compiled on CONFIG_8xx
 * to reduce code space and undefined function references.
 */

#undef DEBUG

#include <linux/module.h>
#include <linux/threads.h>
#include <linux/kernel_stat.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/timex.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/seq_file.h>
#include <linux/cpumask.h>
#include <linux/profile.h>
#include <linux/bitops.h>
#include <linux/list.h>
#include <linux/radix-tree.h>
#include <linux/mutex.h>
#include <linux/bootmem.h>
#include <linux/pci.h>
#include <linux/debugfs.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/irq.h>
#include <asm/cache.h>
#include <asm/prom.h>
#include <asm/ptrace.h>
#include <asm/machdep.h>
#include <asm/udbg.h>
#ifdef CONFIG_PPC64
#include <asm/paca.h>
#include <asm/firmware.h>
#include <asm/lv1call.h>
#endif

int __irq_offset_value;
static int ppc_spurious_interrupts;

#ifdef CONFIG_PPC32
EXPORT_SYMBOL(__irq_offset_value);
atomic_t ppc_n_lost_interrupts;

#ifdef CONFIG_TAU_INT
extern int tau_initialized;
extern int tau_interrupts(int);
#endif
#endif /* CONFIG_PPC32 */

#ifdef CONFIG_PPC64
EXPORT_SYMBOL(irq_desc);

int distribute_irqs = 1;

static inline notrace unsigned long get_hard_enabled(void)
{
      unsigned long enabled;

      __asm__ __volatile__("lbz %0,%1(13)"
      : "=r" (enabled) : "i" (offsetof(struct paca_struct, hard_enabled)));

      return enabled;
}

static inline notrace void set_soft_enabled(unsigned long enable)
{
      __asm__ __volatile__("stb %0,%1(13)"
      : : "r" (enable), "i" (offsetof(struct paca_struct, soft_enabled)));
}

notrace void raw_local_irq_restore(unsigned long en)
{
      /*
       * get_paca()->soft_enabled = en;
       * Is it ever valid to use local_irq_restore(0) when soft_enabled is 1?
       * That was allowed before, and in such a case we do need to take care
       * that gcc will set soft_enabled directly via r13, not choose to use
       * an intermediate register, lest we're preempted to a different cpu.
       */
      set_soft_enabled(en);
      if (!en)
            return;

      if (firmware_has_feature(FW_FEATURE_ISERIES)) {
            /*
             * Do we need to disable preemption here?  Not really: in the
             * unlikely event that we're preempted to a different cpu in
             * between getting r13, loading its lppaca_ptr, and loading
             * its any_int, we might call iseries_handle_interrupts without
             * an interrupt pending on the new cpu, but that's no disaster,
             * is it?  And the business of preempting us off the old cpu
             * would itself involve a local_irq_restore which handles the
             * interrupt to that cpu.
             *
             * But use "local_paca->lppaca_ptr" instead of "get_lppaca()"
             * to avoid any preemption checking added into get_paca().
             */
            if (local_paca->lppaca_ptr->int_dword.any_int)
                  iseries_handle_interrupts();
      }

      /*
       * if (get_paca()->hard_enabled) return;
       * But again we need to take care that gcc gets hard_enabled directly
       * via r13, not choose to use an intermediate register, lest we're
       * preempted to a different cpu in between the two instructions.
       */
      if (get_hard_enabled())
            return;

      /*
       * Need to hard-enable interrupts here.  Since currently disabled,
       * no need to take further asm precautions against preemption; but
       * use local_paca instead of get_paca() to avoid preemption checking.
       */
      local_paca->hard_enabled = en;
      if ((int)mfspr(SPRN_DEC) < 0)
            mtspr(SPRN_DEC, 1);

      /*
       * Force the delivery of pending soft-disabled interrupts on PS3.
       * Any HV call will have this side effect.
       */
      if (firmware_has_feature(FW_FEATURE_PS3_LV1)) {
            u64 tmp;
            lv1_get_version_info(&tmp);
      }

      __hard_irq_enable();
}
EXPORT_SYMBOL(raw_local_irq_restore);
#endif /* CONFIG_PPC64 */

int show_interrupts(struct seq_file *p, void *v)
{
      int i = *(loff_t *)v, j;
      struct irqaction *action;
      irq_desc_t *desc;
      unsigned long flags;

      if (i == 0) {
            seq_puts(p, "           ");
            for_each_online_cpu(j)
                  seq_printf(p, "CPU%d       ", j);
            seq_putc(p, '\n');
      }

      if (i < NR_IRQS) {
            desc = get_irq_desc(i);
            spin_lock_irqsave(&desc->lock, flags);
            action = desc->action;
            if (!action || !action->handler)
                  goto skip;
            seq_printf(p, "%3d: ", i);
#ifdef CONFIG_SMP
            for_each_online_cpu(j)
                  seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
#else
            seq_printf(p, "%10u ", kstat_irqs(i));
#endif /* CONFIG_SMP */
            if (desc->chip)
                  seq_printf(p, " %s ", desc->chip->typename);
            else
                  seq_puts(p, "  None      ");
            seq_printf(p, "%s", (desc->status & IRQ_LEVEL) ? "Level " : "Edge  ");
            seq_printf(p, "    %s", action->name);
            for (action = action->next; action; action = action->next)
                  seq_printf(p, ", %s", action->name);
            seq_putc(p, '\n');
skip:
            spin_unlock_irqrestore(&desc->lock, flags);
      } else if (i == NR_IRQS) {
#if defined(CONFIG_PPC32) && defined(CONFIG_TAU_INT)
            if (tau_initialized){
                  seq_puts(p, "TAU: ");
                  for_each_online_cpu(j)
                        seq_printf(p, "%10u ", tau_interrupts(j));
                  seq_puts(p, "  PowerPC             Thermal Assist (cpu temp)\n");
            }
#endif /* CONFIG_PPC32 && CONFIG_TAU_INT*/
            seq_printf(p, "BAD: %10u\n", ppc_spurious_interrupts);
      }
      return 0;
}

#ifdef CONFIG_HOTPLUG_CPU
void fixup_irqs(cpumask_t map)
{
      unsigned int irq;
      static int warned;

      for_each_irq(irq) {
            cpumask_t mask;

            if (irq_desc[irq].status & IRQ_PER_CPU)
                  continue;

            cpus_and(mask, irq_desc[irq].affinity, map);
            if (any_online_cpu(mask) == NR_CPUS) {
                  printk("Breaking affinity for irq %i\n", irq);
                  mask = map;
            }
            if (irq_desc[irq].chip->set_affinity)
                  irq_desc[irq].chip->set_affinity(irq, mask);
            else if (irq_desc[irq].action && !(warned++))
                  printk("Cannot set affinity for irq %i\n", irq);
      }

      local_irq_enable();
      mdelay(1);
      local_irq_disable();
}
#endif

void do_IRQ(struct pt_regs *regs)
{
      struct pt_regs *old_regs = set_irq_regs(regs);
      unsigned int irq;
#ifdef CONFIG_IRQSTACKS
      struct thread_info *curtp, *irqtp;
#endif

      irq_enter();

#ifdef CONFIG_DEBUG_STACKOVERFLOW
      /* Debugging check for stack overflow: is there less than 2KB free? */
      {
            long sp;

            sp = __get_SP() & (THREAD_SIZE-1);

            if (unlikely(sp < (sizeof(struct thread_info) + 2048))) {
                  printk("do_IRQ: stack overflow: %ld\n",
                        sp - sizeof(struct thread_info));
                  dump_stack();
            }
      }
#endif

      /*
       * Every platform is required to implement ppc_md.get_irq.
       * This function will either return an irq number or NO_IRQ to
       * indicate there are no more pending.
       * The value NO_IRQ_IGNORE is for buggy hardware and means that this
       * IRQ has already been handled. -- Tom
       */
      irq = ppc_md.get_irq();

      if (irq != NO_IRQ && irq != NO_IRQ_IGNORE) {
#ifdef CONFIG_IRQSTACKS
            /* Switch to the irq stack to handle this */
            curtp = current_thread_info();
            irqtp = hardirq_ctx[smp_processor_id()];
            if (curtp != irqtp) {
                  struct irq_desc *desc = irq_desc + irq;
                  void *handler = desc->handle_irq;
                  unsigned long saved_sp_limit = current->thread.ksp_limit;
                  if (handler == NULL)
                        handler = &__do_IRQ;
                  irqtp->task = curtp->task;
                  irqtp->flags = 0;

                  /* Copy the softirq bits in preempt_count so that the
                   * softirq checks work in the hardirq context.
                   */
                  irqtp->preempt_count =
                        (irqtp->preempt_count & ~SOFTIRQ_MASK) |
                        (curtp->preempt_count & SOFTIRQ_MASK);

                  current->thread.ksp_limit = (unsigned long)irqtp +
                        _ALIGN_UP(sizeof(struct thread_info), 16);
                  call_handle_irq(irq, desc, irqtp, handler);
                  current->thread.ksp_limit = saved_sp_limit;
                  irqtp->task = NULL;


                  /* Set any flag that may have been set on the
                   * alternate stack
                   */
                  if (irqtp->flags)
                        set_bits(irqtp->flags, &curtp->flags);
            } else
#endif
                  generic_handle_irq(irq);
      } else if (irq != NO_IRQ_IGNORE)
            /* That's not SMP safe ... but who cares ? */
            ppc_spurious_interrupts++;

      irq_exit();
      set_irq_regs(old_regs);

#ifdef CONFIG_PPC_ISERIES
      if (firmware_has_feature(FW_FEATURE_ISERIES) &&
                  get_lppaca()->int_dword.fields.decr_int) {
            get_lppaca()->int_dword.fields.decr_int = 0;
            /* Signal a fake decrementer interrupt */
            timer_interrupt(regs);
      }
#endif
}

void __init init_IRQ(void)
{
      if (ppc_md.init_IRQ)
            ppc_md.init_IRQ();

      exc_lvl_ctx_init();

      irq_ctx_init();
}

#if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
struct thread_info   *critirq_ctx[NR_CPUS] __read_mostly;
struct thread_info    *dbgirq_ctx[NR_CPUS] __read_mostly;
struct thread_info *mcheckirq_ctx[NR_CPUS] __read_mostly;

void exc_lvl_ctx_init(void)
{
      struct thread_info *tp;
      int i;

      for_each_possible_cpu(i) {
            memset((void *)critirq_ctx[i], 0, THREAD_SIZE);
            tp = critirq_ctx[i];
            tp->cpu = i;
            tp->preempt_count = 0;

#ifdef CONFIG_BOOKE
            memset((void *)dbgirq_ctx[i], 0, THREAD_SIZE);
            tp = dbgirq_ctx[i];
            tp->cpu = i;
            tp->preempt_count = 0;

            memset((void *)mcheckirq_ctx[i], 0, THREAD_SIZE);
            tp = mcheckirq_ctx[i];
            tp->cpu = i;
            tp->preempt_count = HARDIRQ_OFFSET;
#endif
      }
}
#endif

#ifdef CONFIG_IRQSTACKS
struct thread_info *softirq_ctx[NR_CPUS] __read_mostly;
struct thread_info *hardirq_ctx[NR_CPUS] __read_mostly;

void irq_ctx_init(void)
{
      struct thread_info *tp;
      int i;

      for_each_possible_cpu(i) {
            memset((void *)softirq_ctx[i], 0, THREAD_SIZE);
            tp = softirq_ctx[i];
            tp->cpu = i;
            tp->preempt_count = 0;

            memset((void *)hardirq_ctx[i], 0, THREAD_SIZE);
            tp = hardirq_ctx[i];
            tp->cpu = i;
            tp->preempt_count = HARDIRQ_OFFSET;
      }
}

static inline void do_softirq_onstack(void)
{
      struct thread_info *curtp, *irqtp;
      unsigned long saved_sp_limit = current->thread.ksp_limit;

      curtp = current_thread_info();
      irqtp = softirq_ctx[smp_processor_id()];
      irqtp->task = curtp->task;
      current->thread.ksp_limit = (unsigned long)irqtp +
                            _ALIGN_UP(sizeof(struct thread_info), 16);
      call_do_softirq(irqtp);
      current->thread.ksp_limit = saved_sp_limit;
      irqtp->task = NULL;
}

#else
#define do_softirq_onstack()  __do_softirq()
#endif /* CONFIG_IRQSTACKS */

void do_softirq(void)
{
      unsigned long flags;

      if (in_interrupt())
            return;

      local_irq_save(flags);

      if (local_softirq_pending())
            do_softirq_onstack();

      local_irq_restore(flags);
}


/*
 * IRQ controller and virtual interrupts
 */

static LIST_HEAD(irq_hosts);
static DEFINE_SPINLOCK(irq_big_lock);
static unsigned int revmap_trees_allocated;
static DEFINE_MUTEX(revmap_trees_mutex);
struct irq_map_entry irq_map[NR_IRQS];
static unsigned int irq_virq_count = NR_IRQS;
static struct irq_host *irq_default_host;

irq_hw_number_t virq_to_hw(unsigned int virq)
{
      return irq_map[virq].hwirq;
}
EXPORT_SYMBOL_GPL(virq_to_hw);

static int default_irq_host_match(struct irq_host *h, struct device_node *np)
{
      return h->of_node != NULL && h->of_node == np;
}

struct irq_host *irq_alloc_host(struct device_node *of_node,
                        unsigned int revmap_type,
                        unsigned int revmap_arg,
                        struct irq_host_ops *ops,
                        irq_hw_number_t inval_irq)
{
      struct irq_host *host;
      unsigned int size = sizeof(struct irq_host);
      unsigned int i;
      unsigned int *rmap;
      unsigned long flags;

      /* Allocate structure and revmap table if using linear mapping */
      if (revmap_type == IRQ_HOST_MAP_LINEAR)
            size += revmap_arg * sizeof(unsigned int);
      host = zalloc_maybe_bootmem(size, GFP_KERNEL);
      if (host == NULL)
            return NULL;

      /* Fill structure */
      host->revmap_type = revmap_type;
      host->inval_irq = inval_irq;
      host->ops = ops;
      host->of_node = of_node_get(of_node);

      if (host->ops->match == NULL)
            host->ops->match = default_irq_host_match;

      spin_lock_irqsave(&irq_big_lock, flags);

      /* If it's a legacy controller, check for duplicates and
       * mark it as allocated (we use irq 0 host pointer for that
       */
      if (revmap_type == IRQ_HOST_MAP_LEGACY) {
            if (irq_map[0].host != NULL) {
                  spin_unlock_irqrestore(&irq_big_lock, flags);
                  /* If we are early boot, we can't free the structure,
                   * too bad...
                   * this will be fixed once slab is made available early
                   * instead of the current cruft
                   */
                  if (mem_init_done)
                        kfree(host);
                  return NULL;
            }
            irq_map[0].host = host;
      }

      list_add(&host->link, &irq_hosts);
      spin_unlock_irqrestore(&irq_big_lock, flags);

      /* Additional setups per revmap type */
      switch(revmap_type) {
      case IRQ_HOST_MAP_LEGACY:
            /* 0 is always the invalid number for legacy */
            host->inval_irq = 0;
            /* setup us as the host for all legacy interrupts */
            for (i = 1; i < NUM_ISA_INTERRUPTS; i++) {
                  irq_map[i].hwirq = i;
                  smp_wmb();
                  irq_map[i].host = host;
                  smp_wmb();

                  /* Clear norequest flags */
                  get_irq_desc(i)->status &= ~IRQ_NOREQUEST;

                  /* Legacy flags are left to default at this point,
                   * one can then use irq_create_mapping() to
                   * explicitly change them
                   */
                  ops->map(host, i, i);
            }
            break;
      case IRQ_HOST_MAP_LINEAR:
            rmap = (unsigned int *)(host + 1);
            for (i = 0; i < revmap_arg; i++)
                  rmap[i] = NO_IRQ;
            host->revmap_data.linear.size = revmap_arg;
            smp_wmb();
            host->revmap_data.linear.revmap = rmap;
            break;
      default:
            break;
      }

      pr_debug("irq: Allocated host of type %d @0x%p\n", revmap_type, host);

      return host;
}

struct irq_host *irq_find_host(struct device_node *node)
{
      struct irq_host *h, *found = NULL;
      unsigned long flags;

      /* We might want to match the legacy controller last since
       * it might potentially be set to match all interrupts in
       * the absence of a device node. This isn't a problem so far
       * yet though...
       */
      spin_lock_irqsave(&irq_big_lock, flags);
      list_for_each_entry(h, &irq_hosts, link)
            if (h->ops->match(h, node)) {
                  found = h;
                  break;
            }
      spin_unlock_irqrestore(&irq_big_lock, flags);
      return found;
}
EXPORT_SYMBOL_GPL(irq_find_host);

void irq_set_default_host(struct irq_host *host)
{
      pr_debug("irq: Default host set to @0x%p\n", host);

      irq_default_host = host;
}

void irq_set_virq_count(unsigned int count)
{
      pr_debug("irq: Trying to set virq count to %d\n", count);

      BUG_ON(count < NUM_ISA_INTERRUPTS);
      if (count < NR_IRQS)
            irq_virq_count = count;
}

static int irq_setup_virq(struct irq_host *host, unsigned int virq,
                      irq_hw_number_t hwirq)
{
      /* Clear IRQ_NOREQUEST flag */
      get_irq_desc(virq)->status &= ~IRQ_NOREQUEST;

      /* map it */
      smp_wmb();
      irq_map[virq].hwirq = hwirq;
      smp_mb();

      if (host->ops->map(host, virq, hwirq)) {
            pr_debug("irq: -> mapping failed, freeing\n");
            irq_free_virt(virq, 1);
            return -1;
      }

      return 0;
}

unsigned int irq_create_direct_mapping(struct irq_host *host)
{
      unsigned int virq;

      if (host == NULL)
            host = irq_default_host;

      BUG_ON(host == NULL);
      WARN_ON(host->revmap_type != IRQ_HOST_MAP_NOMAP);

      virq = irq_alloc_virt(host, 1, 0);
      if (virq == NO_IRQ) {
            pr_debug("irq: create_direct virq allocation failed\n");
            return NO_IRQ;
      }

      pr_debug("irq: create_direct obtained virq %d\n", virq);

      if (irq_setup_virq(host, virq, virq))
            return NO_IRQ;

      return virq;
}

unsigned int irq_create_mapping(struct irq_host *host,
                        irq_hw_number_t hwirq)
{
      unsigned int virq, hint;

      pr_debug("irq: irq_create_mapping(0x%p, 0x%lx)\n", host, hwirq);

      /* Look for default host if nececssary */
      if (host == NULL)
            host = irq_default_host;
      if (host == NULL) {
            printk(KERN_WARNING "irq_create_mapping called for"
                   " NULL host, hwirq=%lx\n", hwirq);
            WARN_ON(1);
            return NO_IRQ;
      }
      pr_debug("irq: -> using host @%p\n", host);

      /* Check if mapping already exist, if it does, call
       * host->ops->map() to update the flags
       */
      virq = irq_find_mapping(host, hwirq);
      if (virq != NO_IRQ) {
            if (host->ops->remap)
                  host->ops->remap(host, virq, hwirq);
            pr_debug("irq: -> existing mapping on virq %d\n", virq);
            return virq;
      }

      /* Get a virtual interrupt number */
      if (host->revmap_type == IRQ_HOST_MAP_LEGACY) {
            /* Handle legacy */
            virq = (unsigned int)hwirq;
            if (virq == 0 || virq >= NUM_ISA_INTERRUPTS)
                  return NO_IRQ;
            return virq;
      } else {
            /* Allocate a virtual interrupt number */
            hint = hwirq % irq_virq_count;
            virq = irq_alloc_virt(host, 1, hint);
            if (virq == NO_IRQ) {
                  pr_debug("irq: -> virq allocation failed\n");
                  return NO_IRQ;
            }
      }
      pr_debug("irq: -> obtained virq %d\n", virq);

      if (irq_setup_virq(host, virq, hwirq))
            return NO_IRQ;

      return virq;
}
EXPORT_SYMBOL_GPL(irq_create_mapping);

unsigned int irq_create_of_mapping(struct device_node *controller,
                           u32 *intspec, unsigned int intsize)
{
      struct irq_host *host;
      irq_hw_number_t hwirq;
      unsigned int type = IRQ_TYPE_NONE;
      unsigned int virq;

      if (controller == NULL)
            host = irq_default_host;
      else
            host = irq_find_host(controller);
      if (host == NULL) {
            printk(KERN_WARNING "irq: no irq host found for %s !\n",
                   controller->full_name);
            return NO_IRQ;
      }

      /* If host has no translation, then we assume interrupt line */
      if (host->ops->xlate == NULL)
            hwirq = intspec[0];
      else {
            if (host->ops->xlate(host, controller, intspec, intsize,
                             &hwirq, &type))
                  return NO_IRQ;
      }

      /* Create mapping */
      virq = irq_create_mapping(host, hwirq);
      if (virq == NO_IRQ)
            return virq;

      /* Set type if specified and different than the current one */
      if (type != IRQ_TYPE_NONE &&
          type != (get_irq_desc(virq)->status & IRQF_TRIGGER_MASK))
            set_irq_type(virq, type);
      return virq;
}
EXPORT_SYMBOL_GPL(irq_create_of_mapping);

unsigned int irq_of_parse_and_map(struct device_node *dev, int index)
{
      struct of_irq oirq;

      if (of_irq_map_one(dev, index, &oirq))
            return NO_IRQ;

      return irq_create_of_mapping(oirq.controller, oirq.specifier,
                             oirq.size);
}
EXPORT_SYMBOL_GPL(irq_of_parse_and_map);

void irq_dispose_mapping(unsigned int virq)
{
      struct irq_host *host;
      irq_hw_number_t hwirq;

      if (virq == NO_IRQ)
            return;

      host = irq_map[virq].host;
      WARN_ON (host == NULL);
      if (host == NULL)
            return;

      /* Never unmap legacy interrupts */
      if (host->revmap_type == IRQ_HOST_MAP_LEGACY)
            return;

      /* remove chip and handler */
      set_irq_chip_and_handler(virq, NULL, NULL);

      /* Make sure it's completed */
      synchronize_irq(virq);

      /* Tell the PIC about it */
      if (host->ops->unmap)
            host->ops->unmap(host, virq);
      smp_mb();

      /* Clear reverse map */
      hwirq = irq_map[virq].hwirq;
      switch(host->revmap_type) {
      case IRQ_HOST_MAP_LINEAR:
            if (hwirq < host->revmap_data.linear.size)
                  host->revmap_data.linear.revmap[hwirq] = NO_IRQ;
            break;
      case IRQ_HOST_MAP_TREE:
            /*
             * Check if radix tree allocated yet, if not then nothing to
             * remove.
             */
            smp_rmb();
            if (revmap_trees_allocated < 1)
                  break;
            mutex_lock(&revmap_trees_mutex);
            radix_tree_delete(&host->revmap_data.tree, hwirq);
            mutex_unlock(&revmap_trees_mutex);
            break;
      }

      /* Destroy map */
      smp_mb();
      irq_map[virq].hwirq = host->inval_irq;

      /* Set some flags */
      get_irq_desc(virq)->status |= IRQ_NOREQUEST;

      /* Free it */
      irq_free_virt(virq, 1);
}
EXPORT_SYMBOL_GPL(irq_dispose_mapping);

unsigned int irq_find_mapping(struct irq_host *host,
                        irq_hw_number_t hwirq)
{
      unsigned int i;
      unsigned int hint = hwirq % irq_virq_count;

      /* Look for default host if nececssary */
      if (host == NULL)
            host = irq_default_host;
      if (host == NULL)
            return NO_IRQ;

      /* legacy -> bail early */
      if (host->revmap_type == IRQ_HOST_MAP_LEGACY)
            return hwirq;

      /* Slow path does a linear search of the map */
      if (hint < NUM_ISA_INTERRUPTS)
            hint = NUM_ISA_INTERRUPTS;
      i = hint;
      do  {
            if (irq_map[i].host == host &&
                irq_map[i].hwirq == hwirq)
                  return i;
            i++;
            if (i >= irq_virq_count)
                  i = NUM_ISA_INTERRUPTS;
      } while(i != hint);
      return NO_IRQ;
}
EXPORT_SYMBOL_GPL(irq_find_mapping);


unsigned int irq_radix_revmap_lookup(struct irq_host *host,
                             irq_hw_number_t hwirq)
{
      struct irq_map_entry *ptr;
      unsigned int virq;

      WARN_ON(host->revmap_type != IRQ_HOST_MAP_TREE);

      /*
       * Check if the radix tree exists and has bee initialized.
       * If not, we fallback to slow mode
       */
      if (revmap_trees_allocated < 2)
            return irq_find_mapping(host, hwirq);

      /* Now try to resolve */
      /*
       * No rcu_read_lock(ing) needed, the ptr returned can't go under us
       * as it's referencing an entry in the static irq_map table.
       */
      ptr = radix_tree_lookup(&host->revmap_data.tree, hwirq);

      /*
       * If found in radix tree, then fine.
       * Else fallback to linear lookup - this should not happen in practice
       * as it means that we failed to insert the node in the radix tree.
       */
      if (ptr)
            virq = ptr - irq_map;
      else
            virq = irq_find_mapping(host, hwirq);

      return virq;
}

void irq_radix_revmap_insert(struct irq_host *host, unsigned int virq,
                       irq_hw_number_t hwirq)
{

      WARN_ON(host->revmap_type != IRQ_HOST_MAP_TREE);

      /*
       * Check if the radix tree exists yet.
       * If not, then the irq will be inserted into the tree when it gets
       * initialized.
       */
      smp_rmb();
      if (revmap_trees_allocated < 1)
            return;

      if (virq != NO_IRQ) {
            mutex_lock(&revmap_trees_mutex);
            radix_tree_insert(&host->revmap_data.tree, hwirq,
                          &irq_map[virq]);
            mutex_unlock(&revmap_trees_mutex);
      }
}

unsigned int irq_linear_revmap(struct irq_host *host,
                         irq_hw_number_t hwirq)
{
      unsigned int *revmap;

      WARN_ON(host->revmap_type != IRQ_HOST_MAP_LINEAR);

      /* Check revmap bounds */
      if (unlikely(hwirq >= host->revmap_data.linear.size))
            return irq_find_mapping(host, hwirq);

      /* Check if revmap was allocated */
      revmap = host->revmap_data.linear.revmap;
      if (unlikely(revmap == NULL))
            return irq_find_mapping(host, hwirq);

      /* Fill up revmap with slow path if no mapping found */
      if (unlikely(revmap[hwirq] == NO_IRQ))
            revmap[hwirq] = irq_find_mapping(host, hwirq);

      return revmap[hwirq];
}

unsigned int irq_alloc_virt(struct irq_host *host,
                      unsigned int count,
                      unsigned int hint)
{
      unsigned long flags;
      unsigned int i, j, found = NO_IRQ;

      if (count == 0 || count > (irq_virq_count - NUM_ISA_INTERRUPTS))
            return NO_IRQ;

      spin_lock_irqsave(&irq_big_lock, flags);

      /* Use hint for 1 interrupt if any */
      if (count == 1 && hint >= NUM_ISA_INTERRUPTS &&
          hint < irq_virq_count && irq_map[hint].host == NULL) {
            found = hint;
            goto hint_found;
      }

      /* Look for count consecutive numbers in the allocatable
       * (non-legacy) space
       */
      for (i = NUM_ISA_INTERRUPTS, j = 0; i < irq_virq_count; i++) {
            if (irq_map[i].host != NULL)
                  j = 0;
            else
                  j++;

            if (j == count) {
                  found = i - count + 1;
                  break;
            }
      }
      if (found == NO_IRQ) {
            spin_unlock_irqrestore(&irq_big_lock, flags);
            return NO_IRQ;
      }
 hint_found:
      for (i = found; i < (found + count); i++) {
            irq_map[i].hwirq = host->inval_irq;
            smp_wmb();
            irq_map[i].host = host;
      }
      spin_unlock_irqrestore(&irq_big_lock, flags);
      return found;
}

void irq_free_virt(unsigned int virq, unsigned int count)
{
      unsigned long flags;
      unsigned int i;

      WARN_ON (virq < NUM_ISA_INTERRUPTS);
      WARN_ON (count == 0 || (virq + count) > irq_virq_count);

      spin_lock_irqsave(&irq_big_lock, flags);
      for (i = virq; i < (virq + count); i++) {
            struct irq_host *host;

            if (i < NUM_ISA_INTERRUPTS ||
                (virq + count) > irq_virq_count)
                  continue;

            host = irq_map[i].host;
            irq_map[i].hwirq = host->inval_irq;
            smp_wmb();
            irq_map[i].host = NULL;
      }
      spin_unlock_irqrestore(&irq_big_lock, flags);
}

void irq_early_init(void)
{
      unsigned int i;

      for (i = 0; i < NR_IRQS; i++)
            get_irq_desc(i)->status |= IRQ_NOREQUEST;
}

/* We need to create the radix trees late */
static int irq_late_init(void)
{
      struct irq_host *h;
      unsigned int i;

      /*
       * No mutual exclusion with respect to accessors of the tree is needed
       * here as the synchronization is done via the state variable
       * revmap_trees_allocated.
       */
      list_for_each_entry(h, &irq_hosts, link) {
            if (h->revmap_type == IRQ_HOST_MAP_TREE)
                  INIT_RADIX_TREE(&h->revmap_data.tree, GFP_KERNEL);
      }

      /*
       * Make sure the radix trees inits are visible before setting
       * the flag
       */
      smp_wmb();
      revmap_trees_allocated = 1;

      /*
       * Insert the reverse mapping for those interrupts already present
       * in irq_map[].
       */
      mutex_lock(&revmap_trees_mutex);
      for (i = 0; i < irq_virq_count; i++) {
            if (irq_map[i].host &&
                (irq_map[i].host->revmap_type == IRQ_HOST_MAP_TREE))
                  radix_tree_insert(&irq_map[i].host->revmap_data.tree,
                                irq_map[i].hwirq, &irq_map[i]);
      }
      mutex_unlock(&revmap_trees_mutex);

      /*
       * Make sure the radix trees insertions are visible before setting
       * the flag
       */
      smp_wmb();
      revmap_trees_allocated = 2;

      return 0;
}
arch_initcall(irq_late_init);

#ifdef CONFIG_VIRQ_DEBUG
static int virq_debug_show(struct seq_file *m, void *private)
{
      unsigned long flags;
      irq_desc_t *desc;
      const char *p;
      char none[] = "none";
      int i;

      seq_printf(m, "%-5s  %-7s  %-15s  %s\n", "virq", "hwirq",
                  "chip name", "host name");

      for (i = 1; i < NR_IRQS; i++) {
            desc = get_irq_desc(i);
            spin_lock_irqsave(&desc->lock, flags);

            if (desc->action && desc->action->handler) {
                  seq_printf(m, "%5d  ", i);
                  seq_printf(m, "0x%05lx  ", virq_to_hw(i));

                  if (desc->chip && desc->chip->typename)
                        p = desc->chip->typename;
                  else
                        p = none;
                  seq_printf(m, "%-15s  ", p);

                  if (irq_map[i].host && irq_map[i].host->of_node)
                        p = irq_map[i].host->of_node->full_name;
                  else
                        p = none;
                  seq_printf(m, "%s\n", p);
            }

            spin_unlock_irqrestore(&desc->lock, flags);
      }

      return 0;
}

static int virq_debug_open(struct inode *inode, struct file *file)
{
      return single_open(file, virq_debug_show, inode->i_private);
}

static const struct file_operations virq_debug_fops = {
      .open = virq_debug_open,
      .read = seq_read,
      .llseek = seq_lseek,
      .release = single_release,
};

static int __init irq_debugfs_init(void)
{
      if (debugfs_create_file("virq_mapping", S_IRUGO, powerpc_debugfs_root,
                         NULL, &virq_debug_fops) == NULL)
            return -ENOMEM;

      return 0;
}
__initcall(irq_debugfs_init);
#endif /* CONFIG_VIRQ_DEBUG */

#ifdef CONFIG_PPC64
static int __init setup_noirqdistrib(char *str)
{
      distribute_irqs = 0;
      return 1;
}

__setup("noirqdistrib", setup_noirqdistrib);
#endif /* CONFIG_PPC64 */

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