initial_commit

1 files changed, 1117 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
new file mode 100644
index 00000000..ca2987d9
--- /dev/null
+++ b/arch/powerpc/kernel/irq.c
@@ -0,0 +1,1117 @@
+/*
+ *  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 <linux/of.h>
+#include <linux/of_irq.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>
+#include <asm/smp.h>
+
+#ifdef CONFIG_PPC64
+#include <asm/paca.h>
+#include <asm/firmware.h>
+#include <asm/lv1call.h>
+#endif
+#define CREATE_TRACE_POINTS
+#include <asm/trace.h>
+
+DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
+EXPORT_PER_CPU_SYMBOL(irq_stat);
+
+int __irq_offset_value;
+
+#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
+
+#ifndef CONFIG_SPARSE_IRQ
+EXPORT_SYMBOL(irq_desc);
+#endif
+
+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 arch_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;
+
+#ifdef CONFIG_PPC_STD_MMU_64
+	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();
+	}
+#endif /* CONFIG_PPC_STD_MMU_64 */
+
+	/*
+	 * 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;
+
+#if defined(CONFIG_BOOKE) && defined(CONFIG_SMP)
+	/* Check for pending doorbell interrupts and resend to ourself */
+	if (cpu_has_feature(CPU_FTR_DBELL))
+		smp_muxed_ipi_resend();
+#endif
+
+	/*
+	 * 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;
+
+	/*
+	 * Trigger the decrementer if we have a pending event. Some processors
+	 * only trigger on edge transitions of the sign bit. We might also
+	 * have disabled interrupts long enough that the decrementer wrapped
+	 * to positive.
+	 */
+	decrementer_check_overflow();
+
+	/*
+	 * 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(arch_local_irq_restore);
+#endif /* CONFIG_PPC64 */
+
+int arch_show_interrupts(struct seq_file *p, int prec)
+{
+	int j;
+
+#if defined(CONFIG_PPC32) && defined(CONFIG_TAU_INT)
+	if (tau_initialized) {
+		seq_printf(p, "%*s: ", prec, "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, "%*s: ", prec, "LOC");
+	for_each_online_cpu(j)
+		seq_printf(p, "%10u ", per_cpu(irq_stat, j).timer_irqs);
+        seq_printf(p, "  Local timer interrupts\n");
+
+	seq_printf(p, "%*s: ", prec, "SPU");
+	for_each_online_cpu(j)
+		seq_printf(p, "%10u ", per_cpu(irq_stat, j).spurious_irqs);
+	seq_printf(p, "  Spurious interrupts\n");
+
+	seq_printf(p, "%*s: ", prec, "CNT");
+	for_each_online_cpu(j)
+		seq_printf(p, "%10u ", per_cpu(irq_stat, j).pmu_irqs);
+	seq_printf(p, "  Performance monitoring interrupts\n");
+
+	seq_printf(p, "%*s: ", prec, "MCE");
+	for_each_online_cpu(j)
+		seq_printf(p, "%10u ", per_cpu(irq_stat, j).mce_exceptions);
+	seq_printf(p, "  Machine check exceptions\n");
+
+	return 0;
+}
+
+/*
+ * /proc/stat helpers
+ */
+u64 arch_irq_stat_cpu(unsigned int cpu)
+{
+	u64 sum = per_cpu(irq_stat, cpu).timer_irqs;
+
+	sum += per_cpu(irq_stat, cpu).pmu_irqs;
+	sum += per_cpu(irq_stat, cpu).mce_exceptions;
+	sum += per_cpu(irq_stat, cpu).spurious_irqs;
+
+	return sum;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+void migrate_irqs(void)
+{
+	struct irq_desc *desc;
+	unsigned int irq;
+	static int warned;
+	cpumask_var_t mask;
+	const struct cpumask *map = cpu_online_mask;
+
+	alloc_cpumask_var(&mask, GFP_KERNEL);
+
+	for_each_irq(irq) {
+		struct irq_data *data;
+		struct irq_chip *chip;
+
+		desc = irq_to_desc(irq);
+		if (!desc)
+			continue;
+
+		data = irq_desc_get_irq_data(desc);
+		if (irqd_is_per_cpu(data))
+			continue;
+
+		chip = irq_data_get_irq_chip(data);
+
+		cpumask_and(mask, data->affinity, map);
+		if (cpumask_any(mask) >= nr_cpu_ids) {
+			printk("Breaking affinity for irq %i\n", irq);
+			cpumask_copy(mask, map);
+		}
+		if (chip->irq_set_affinity)
+			chip->irq_set_affinity(data, mask, true);
+		else if (desc->action && !(warned++))
+			printk("Cannot set affinity for irq %i\n", irq);
+	}
+
+	free_cpumask_var(mask);
+
+	local_irq_enable();
+	mdelay(1);
+	local_irq_disable();
+}
+#endif
+
+static inline void handle_one_irq(unsigned int irq)
+{
+	struct thread_info *curtp, *irqtp;
+	unsigned long saved_sp_limit;
+	struct irq_desc *desc;
+
+	desc = irq_to_desc(irq);
+	if (!desc)
+		return;
+
+	/* Switch to the irq stack to handle this */
+	curtp = current_thread_info();
+	irqtp = hardirq_ctx[smp_processor_id()];
+
+	if (curtp == irqtp) {
+		/* We're already on the irq stack, just handle it */
+		desc->handle_irq(irq, desc);
+		return;
+	}
+
+	saved_sp_limit = current->thread.ksp_limit;
+
+	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, desc->handle_irq);
+	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);
+}
+
+static inline void check_stack_overflow(void)
+{
+#ifdef CONFIG_DEBUG_STACKOVERFLOW
+	long sp;
+
+	sp = __get_SP() & (THREAD_SIZE-1);
+
+	/* check for stack overflow: is there less than 2KB free? */
+	if (unlikely(sp < (sizeof(struct thread_info) + 2048))) {
+		printk("do_IRQ: stack overflow: %ld\n",
+			sp - sizeof(struct thread_info));
+		dump_stack();
+	}
+#endif
+}
+
+void do_IRQ(struct pt_regs *regs)
+{
+	struct pt_regs *old_regs = set_irq_regs(regs);
+	unsigned int irq;
+
+	trace_irq_entry(regs);
+
+	irq_enter();
+
+	check_stack_overflow();
+
+	irq = ppc_md.get_irq();
+
+	if (irq != NO_IRQ && irq != NO_IRQ_IGNORE)
+		handle_one_irq(irq);
+	else if (irq != NO_IRQ_IGNORE)
+		__get_cpu_var(irq_stat).spurious_irqs++;
+
+	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
+
+	trace_irq_exit(regs);
+}
+
+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, cpu_nr;
+
+	for_each_possible_cpu(i) {
+#ifdef CONFIG_PPC64
+		cpu_nr = i;
+#else
+		cpu_nr = get_hard_smp_processor_id(i);
+#endif
+		memset((void *)critirq_ctx[cpu_nr], 0, THREAD_SIZE);
+		tp = critirq_ctx[cpu_nr];
+		tp->cpu = cpu_nr;
+		tp->preempt_count = 0;
+
+#ifdef CONFIG_BOOKE
+		memset((void *)dbgirq_ctx[cpu_nr], 0, THREAD_SIZE);
+		tp = dbgirq_ctx[cpu_nr];
+		tp->cpu = cpu_nr;
+		tp->preempt_count = 0;
+
+		memset((void *)mcheckirq_ctx[cpu_nr], 0, THREAD_SIZE);
+		tp = mcheckirq_ctx[cpu_nr];
+		tp->cpu = cpu_nr;
+		tp->preempt_count = HARDIRQ_OFFSET;
+#endif
+	}
+}
+#endif
+
+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;
+}
+
+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
+ */
+
+/* The main irq map itself is an array of NR_IRQ entries containing the
+ * associate host and irq number. An entry with a host of NULL is free.
+ * An entry can be allocated if it's free, the allocator always then sets
+ * hwirq first to the host's invalid irq number and then fills ops.
+ */
+struct irq_map_entry {
+	irq_hw_number_t	hwirq;
+	struct irq_host	*host;
+};
+
+static LIST_HEAD(irq_hosts);
+static DEFINE_RAW_SPINLOCK(irq_big_lock);
+static DEFINE_MUTEX(revmap_trees_mutex);
+static 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 irqd_to_hwirq(struct irq_data *d)
+{
+	return irq_map[d->irq].hwirq;
+}
+EXPORT_SYMBOL_GPL(irqd_to_hwirq);
+
+irq_hw_number_t virq_to_hw(unsigned int virq)
+{
+	return irq_map[virq].hwirq;
+}
+EXPORT_SYMBOL_GPL(virq_to_hw);
+
+bool virq_is_host(unsigned int virq, struct irq_host *host)
+{
+	return irq_map[virq].host == host;
+}
+EXPORT_SYMBOL_GPL(virq_is_host);
+
+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 = kzalloc(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;
+
+	raw_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) {
+			raw_spin_unlock_irqrestore(&irq_big_lock, flags);
+			of_node_put(host->of_node);
+			kfree(host);
+			return NULL;
+		}
+		irq_map[0].host = host;
+	}
+
+	list_add(&host->link, &irq_hosts);
+	raw_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();
+
+			/* 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);
+
+			/* Clear norequest flags */
+			irq_clear_status_flags(i, IRQ_NOREQUEST);
+		}
+		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;
+	case IRQ_HOST_MAP_TREE:
+		INIT_RADIX_TREE(&host->revmap_data.tree, GFP_KERNEL);
+		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...
+	 */
+	raw_spin_lock_irqsave(&irq_big_lock, flags);
+	list_for_each_entry(h, &irq_hosts, link)
+		if (h->ops->match(h, node)) {
+			found = h;
+			break;
+		}
+	raw_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)
+{
+	int res;
+
+	res = irq_alloc_desc_at(virq, 0);
+	if (res != virq) {
+		pr_debug("irq: -> allocating desc failed\n");
+		goto error;
+	}
+
+	/* 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");
+		goto errdesc;
+	}
+
+	irq_clear_status_flags(virq, IRQ_NOREQUEST);
+
+	return 0;
+
+errdesc:
+	irq_free_descs(virq, 1);
+error:
+	irq_free_virt(virq, 1);
+	return -1;
+}
+
+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 exists */
+	virq = irq_find_mapping(host, hwirq);
+	if (virq != NO_IRQ) {
+		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,
+				   const 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 != (irqd_get_trigger_type(irq_get_irq_data(virq))))
+		irq_set_irq_type(virq, type);
+	return virq;
+}
+EXPORT_SYMBOL_GPL(irq_create_of_mapping);
+
+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;
+	if (WARN_ON(host == NULL))
+		return;
+
+	/* Never unmap legacy interrupts */
+	if (host->revmap_type == IRQ_HOST_MAP_LEGACY)
+		return;
+
+	irq_set_status_flags(virq, IRQ_NOREQUEST);
+
+	/* remove chip and handler */
+	irq_set_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:
+		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;
+
+	irq_free_descs(virq, 1);
+	/* 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;
+
+	if (WARN_ON_ONCE(host->revmap_type != IRQ_HOST_MAP_TREE))
+		return irq_find_mapping(host, hwirq);
+
+	/*
+	 * The ptr returned references the static global irq_map.
+	 * but freeing an irq can delete nodes along the path to
+	 * do the lookup via call_rcu.
+	 */
+	rcu_read_lock();
+	ptr = radix_tree_lookup(&host->revmap_data.tree, hwirq);
+	rcu_read_unlock();
+
+	/*
+	 * 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)
+{
+	if (WARN_ON(host->revmap_type != IRQ_HOST_MAP_TREE))
+		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;
+
+	if (WARN_ON_ONCE(host->revmap_type != IRQ_HOST_MAP_LINEAR))
+		return irq_find_mapping(host, hwirq);
+
+	/* 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;
+
+	raw_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) {
+		raw_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;
+	}
+	raw_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);
+
+	if (virq < NUM_ISA_INTERRUPTS) {
+		if (virq + count < NUM_ISA_INTERRUPTS)
+			return;
+		count  =- NUM_ISA_INTERRUPTS - virq;
+		virq = NUM_ISA_INTERRUPTS;
+	}
+
+	if (count > irq_virq_count || virq > irq_virq_count - count) {
+		if (virq > irq_virq_count)
+			return;
+		count = irq_virq_count - virq;
+	}
+
+	raw_spin_lock_irqsave(&irq_big_lock, flags);
+	for (i = virq; i < (virq + count); i++) {
+		struct irq_host *host;
+
+		host = irq_map[i].host;
+		irq_map[i].hwirq = host->inval_irq;
+		smp_wmb();
+		irq_map[i].host = NULL;
+	}
+	raw_spin_unlock_irqrestore(&irq_big_lock, flags);
+}
+
+int arch_early_irq_init(void)
+{
+	return 0;
+}
+
+#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;
+	static const char none[] = "none";
+	void *data;
+	int i;
+
+	seq_printf(m, "%-5s  %-7s  %-15s  %-18s  %s\n", "virq", "hwirq",
+		      "chip name", "chip data", "host name");
+
+	for (i = 1; i < nr_irqs; i++) {
+		desc = irq_to_desc(i);
+		if (!desc)
+			continue;
+
+		raw_spin_lock_irqsave(&desc->lock, flags);
+
+		if (desc->action && desc->action->handler) {
+			struct irq_chip *chip;
+
+			seq_printf(m, "%5d  ", i);
+			seq_printf(m, "0x%05lx  ", irq_map[i].hwirq);
+
+			chip = irq_desc_get_chip(desc);
+			if (chip && chip->name)
+				p = chip->name;
+			else
+				p = none;
+			seq_printf(m, "%-15s  ", p);
+
+			data = irq_desc_get_chip_data(desc);
+			seq_printf(m, "0x%16p  ", data);
+
+			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);
+		}
+
+		raw_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 */