Blackfin SPI Driver: pass DMA overflow error to the higher level

[linux-2.6/mini2440.git] / arch / powerpc / kernel / 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;
        struct irq_desc *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_irqs_cpu(i, j));
#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;

                cpumask_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;
                }
        }

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

        printk(KERN_DEBUG "irq: irq %lu on host %s mapped to virtual irq %u\n",
                hwirq, host->of_node ? host->of_node->full_name : "null", virq);

        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;
        struct irq_desc *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 */