Subject: RE: [RFC] irq: Migrate powerpc virq subsystem into generic code

From: Benjamin Herrenschmidt <[email-masked]>
Date: Sat, 02 Oct 2010 11:02:23 +1000

On Fri, 2010-10-01 at 13:44 +0100, Lorenzo Pieralisi wrote:
> Hi Grant, Ben, all

Hi Lorenzo,

> I have a question on the PowerPC IRQ layer and how to use it
> for device drivers and device tree in general.
> 
> A device such as eth smsc911x (example) requires the platform_data 
> pointer to specify irq sense/level to programme the chip accordingly. 
> As agreed with Grant these pieces of information should be retrieved 
> from the device tree, from the interrupt-specifier.

Right.

> Now: the device driver should be interrupt-controller agnostic, so
> I cannot just retrieve the interrupts property at probe and decode it
> in order to get the interrupt sense/level bits (the driver has no clue 
> about the interrupt-controller irq flags encoding).

Indeed.

> I need to associate a irq_host to the interrupt controller node, with
> a proper xlate function to correctly decode the interrupt-specifier 
> and set the irq type accordingly (irq_create_of_mapping(),
> for now 1:1 on ARM, so useless from this standpoint).

Yes, basically -something- at some stage will translate the IRQ
"host" (let's call it "domain" instead, that was a bad naming choice
from me initially) and HW number within that domain to a newly allocated
linux "virq" number (the irq number manipulated generically in Linux).

The way that works is actually quite simple, but let me reply to you
first and then fill in the blanks...

> At platform device init time, of_irq_to_resource() is called to parse
> and map irqs; if we code the irq_host correctly for the ARM GIC for
> instance the xlate function gets called and irq type set accordingly
> (and maybe the function could set platform_device IRQ resource 
> flags as well ?)

Yes. It should basically all happen automatically from that standpoint
so the driver has nothing else to do but call something like
of_irq_to_resource(). This is a high level function tho, and if so
desired, lower level functions are also accessible if the driver or the
platform which to "tweak" thing a bit.

For example, if the device-tree misses something, or interrupts for a
given device are dynamically allocated in HW (such as MSIs), you can
also call irq_create_mapping() directly to allocate virq's and associate
them to host(domain)/hw_number pairs. This is typically done in MSI
backends.

In fact, cascaded controllers tend to basically just be devices nodes
that are both an interrupt-parent and have an interrupt parent &
interrupts property(ies).

So the cascaded controller does of_irq_to_resource() for example to
obtain its own "upstream" IRQ and request it.

The net result is you no longer have to create some "global" numbering
scheme with magic offsets and range for various cascaded or separate
controllers in a SoC setup. The HW numbering is local to a given domain
(typically a PIC but in some cases, it could extend accross multiple
copies of the same PIC in SMP that share a global interrupt domain), and
the linux numbers dynamically allocated.

> At driver dt probe, from the hwirq number defined in "interrupts"
> the driver retrieves the virq, hence sense/level flags and use them,
> or just use the platform_device IRQ resource flags if set properly
> by the OF layer. 

Right so generally drivers don't care about the details, they just use a
helper like of_irq_to_resource() that does it for them. But if they
want, they can call lower level things to parse the interrupts property,
and then establish a mapping etc... they can also override the flags,
that sort of thing.

> Correct ?

That's the idea ... minus bugs :-) We haven't been using interrupt
"resources" that much on powerpc in the past so we may have bugs setting
the flags there, but I suppose Grant is fixing all of that. We used to
just set the flags in the irq desc directly when doing the mapping of
the virq.

> If yes I will have a stab at it on a ARM platform with complex
> IRQ routing.
> 
> Thank you very much.

My pleasure,

Cheers,
Ben.

> Cheers,
> Lorenzo
> 
> > 
> >  arch/microblaze/kernel/setup.c |    2
> >  arch/powerpc/Kconfig           |    3
> >  arch/powerpc/include/asm/irq.h |  270 ----------------
> >  arch/powerpc/kernel/irq.c      |  659 --------------------------------
> > ------
> >  include/linux/virq.h           |  302 ++++++++++++++++++
> >  kernel/irq/Makefile            |    1
> >  kernel/irq/virq.c              |  687
> > ++++++++++++++++++++++++++++++++++++++++
> >  7 files changed, 995 insertions(+), 929 deletions(-)
> >  create mode 100644 include/linux/virq.h
> >  create mode 100644 kernel/irq/virq.c
> > 
> > diff --git a/arch/microblaze/kernel/setup.c
> > b/arch/microblaze/kernel/setup.c
> > index f5f7688..39cf20d 100644
> > --- a/arch/microblaze/kernel/setup.c
> > +++ b/arch/microblaze/kernel/setup.c
> > @@ -51,8 +51,6 @@ void __init setup_arch(char **cmdline_p)
> > 
> >  	unflatten_device_tree();
> > 
> > -	/* NOTE I think that this function is not necessary to call */
> > -	/* irq_early_init(); */
> >  	setup_cpuinfo();
> > 
> >  	microblaze_cache_init();
> > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> > index 631e5a0..cc06e59 100644
> > --- a/arch/powerpc/Kconfig
> > +++ b/arch/powerpc/Kconfig
> > @@ -146,6 +146,9 @@ config EARLY_PRINTK
> >  	bool
> >  	default y
> > 
> > +config VIRQ
> > +	def_bool y
> > +
> >  config COMPAT
> >  	bool
> >  	default y if PPC64
> > diff --git a/arch/powerpc/include/asm/irq.h
> > b/arch/powerpc/include/asm/irq.h
> > index 67ab5fb..6dea0cb 100644
> > --- a/arch/powerpc/include/asm/irq.h
> > +++ b/arch/powerpc/include/asm/irq.h
> > @@ -17,10 +17,6 @@
> >  #include <asm/atomic.h>
> > 
> > 
> > -/* Define a way to iterate across irqs. */
> > -#define for_each_irq(i) \
> > -	for ((i) = 0; (i) < NR_IRQS; ++(i))
> > -
> >  extern atomic_t ppc_n_lost_interrupts;
> > 
> >  /* This number is used when no interrupt has been assigned */
> > @@ -41,270 +37,6 @@ extern atomic_t ppc_n_lost_interrupts;
> >  /* Same thing, used by the generic IRQ code */
> >  #define NR_IRQS_LEGACY		NUM_ISA_INTERRUPTS
> > 
> > -/* This type is the placeholder for a hardware interrupt number. It
> > has to
> > - * be big enough to enclose whatever representation is used by a given
> > - * platform.
> > - */
> > -typedef unsigned long irq_hw_number_t;
> > -
> > -/* Interrupt controller "host" data structure. This could be defined
> > as a
> > - * irq domain controller. That is, it handles the mapping between
> > hardware
> > - * and virtual interrupt numbers for a given interrupt domain. The
> > host
> > - * structure is generally created by the PIC code for a given PIC
> > instance
> > - * (though a host can cover more than one PIC if they have a flat
> > number
> > - * model). It's the host callbacks that are responsible for setting
> > the
> > - * irq_chip on a given irq_desc after it's been mapped.
> > - *
> > - * The host code and data structures are fairly agnostic to the fact
> > that
> > - * we use an open firmware device-tree. We do have references to
> > struct
> > - * device_node in two places: in irq_find_host() to find the host
> > matching
> > - * a given interrupt controller node, and of course as an argument to
> > its
> > - * counterpart host->ops->match() callback. However, those are treated
> > as
> > - * generic pointers by the core and the fact that it's actually a
> > device-node
> > - * pointer is purely a convention between callers and implementation.
> > This
> > - * code could thus be used on other architectures by replacing those
> > two
> > - * by some sort of arch-specific void * "token" used to identify
> > interrupt
> > - * controllers.
> > - */
> > -struct irq_host;
> > -struct radix_tree_root;
> > -
> > -/* Functions below are provided by the host and called whenever a new
> > mapping
> > - * is created or an old mapping is disposed. The host can then proceed
> > to
> > - * whatever internal data structures management is required. It also
> > needs
> > - * to setup the irq_desc when returning from map().
> > - */
> > -struct irq_host_ops {
> > -	/* Match an interrupt controller device node to a host, returns
> > -	 * 1 on a match
> > -	 */
> > -	int (*match)(struct irq_host *h, struct device_node *node);
> > -
> > -	/* Create or update a mapping between a virtual irq number and a
> > hw
> > -	 * irq number. This is called only once for a given mapping.
> > -	 */
> > -	int (*map)(struct irq_host *h, unsigned int virq, irq_hw_number_t
> > hw);
> > -
> > -	/* Dispose of such a mapping */
> > -	void (*unmap)(struct irq_host *h, unsigned int virq);
> > -
> > -	/* Update of such a mapping  */
> > -	void (*remap)(struct irq_host *h, unsigned int virq,
> > irq_hw_number_t hw);
> > -
> > -	/* Translate device-tree interrupt specifier from raw format
> > coming
> > -	 * from the firmware to a irq_hw_number_t (interrupt line number)
> > and
> > -	 * type (sense) that can be passed to set_irq_type(). In the
> > absence
> > -	 * of this callback, irq_create_of_mapping() and
> > irq_of_parse_and_map()
> > -	 * will return the hw number in the first cell and IRQ_TYPE_NONE
> > for
> > -	 * the type (which amount to keeping whatever default value the
> > -	 * interrupt controller has for that line)
> > -	 */
> > -	int (*xlate)(struct irq_host *h, struct device_node *ctrler,
> > -		     const u32 *intspec, unsigned int intsize,
> > -		     irq_hw_number_t *out_hwirq, unsigned int *out_type);
> > -};
> > -
> > -struct irq_host {
> > -	struct list_head	link;
> > -
> > -	/* type of reverse mapping technique */
> > -	unsigned int		revmap_type;
> > -#define IRQ_HOST_MAP_LEGACY     0 /* legacy 8259, gets irqs 1..15 */
> > -#define IRQ_HOST_MAP_NOMAP	1 /* no fast reverse mapping */
> > -#define IRQ_HOST_MAP_LINEAR	2 /* linear map of interrupts */
> > -#define IRQ_HOST_MAP_TREE	3 /* radix tree */
> > -	union {
> > -		struct {
> > -			unsigned int size;
> > -			unsigned int *revmap;
> > -		} linear;
> > -		struct radix_tree_root tree;
> > -	} revmap_data;
> > -	struct irq_host_ops	*ops;
> > -	void			*host_data;
> > -	irq_hw_number_t		inval_irq;
> > -
> > -	/* Optional device node pointer */
> > -	struct device_node	*of_node;
> > -};
> > -
> > -/* 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;
> > -};
> > -
> > -extern struct irq_map_entry irq_map[NR_IRQS];
> > -
> > -extern irq_hw_number_t virq_to_hw(unsigned int virq);
> > -
> > -/**
> > - * irq_alloc_host - Allocate a new irq_host data structure
> > - * @of_node: optional device-tree node of the interrupt controller
> > - * @revmap_type: type of reverse mapping to use
> > - * @revmap_arg: for IRQ_HOST_MAP_LINEAR linear only: size of the map
> > - * @ops: map/unmap host callbacks
> > - * @inval_irq: provide a hw number in that host space that is always
> > invalid
> > - *
> > - * Allocates and initialize and irq_host structure. Note that in the
> > case of
> > - * IRQ_HOST_MAP_LEGACY, the map() callback will be called before this
> > returns
> > - * for all legacy interrupts except 0 (which is always the invalid irq
> > for
> > - * a legacy controller). For a IRQ_HOST_MAP_LINEAR, the map is
> > allocated by
> > - * this call as well. For a IRQ_HOST_MAP_TREE, the radix tree will be
> > allocated
> > - * later during boot automatically (the reverse mapping will use the
> > slow path
> > - * until that happens).
> > - */
> > -extern 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);
> > -
> > -
> > -/**
> > - * irq_find_host - Locates a host for a given device node
> > - * @node: device-tree node of the interrupt controller
> > - */
> > -extern struct irq_host *irq_find_host(struct device_node *node);
> > -
> > -
> > -/**
> > - * irq_set_default_host - Set a "default" host
> > - * @host: default host pointer
> > - *
> > - * For convenience, it's possible to set a "default" host that will be
> > used
> > - * whenever NULL is passed to irq_create_mapping(). It makes life
> > easier for
> > - * platforms that want to manipulate a few hard coded interrupt
> > numbers that
> > - * aren't properly represented in the device-tree.
> > - */
> > -extern void irq_set_default_host(struct irq_host *host);
> > -
> > -
> > -/**
> > - * irq_set_virq_count - Set the maximum number of virt irqs
> > - * @count: number of linux virtual irqs, capped with NR_IRQS
> > - *
> > - * This is mainly for use by platforms like iSeries who want to
> > program
> > - * the virtual irq number in the controller to avoid the reverse
> > mapping
> > - */
> > -extern void irq_set_virq_count(unsigned int count);
> > -
> > -
> > -/**
> > - * irq_create_mapping - Map a hardware interrupt into linux virq space
> > - * @host: host owning this hardware interrupt or NULL for default host
> > - * @hwirq: hardware irq number in that host space
> > - *
> > - * Only one mapping per hardware interrupt is permitted. Returns a
> > linux
> > - * virq number.
> > - * If the sense/trigger is to be specified, set_irq_type() should be
> > called
> > - * on the number returned from that call.
> > - */
> > -extern unsigned int irq_create_mapping(struct irq_host *host,
> > -				       irq_hw_number_t hwirq);
> > -
> > -
> > -/**
> > - * irq_dispose_mapping - Unmap an interrupt
> > - * @virq: linux virq number of the interrupt to unmap
> > - */
> > -extern void irq_dispose_mapping(unsigned int virq);
> > -
> > -/**
> > - * irq_find_mapping - Find a linux virq from an hw irq number.
> > - * @host: host owning this hardware interrupt
> > - * @hwirq: hardware irq number in that host space
> > - *
> > - * This is a slow path, for use by generic code. It's expected that an
> > - * irq controller implementation directly calls the appropriate low
> > level
> > - * mapping function.
> > - */
> > -extern unsigned int irq_find_mapping(struct irq_host *host,
> > -				     irq_hw_number_t hwirq);
> > -
> > -/**
> > - * irq_create_direct_mapping - Allocate a virq for direct mapping
> > - * @host: host to allocate the virq for or NULL for default host
> > - *
> > - * This routine is used for irq controllers which can choose the
> > hardware
> > - * interrupt numbers they generate. In such a case it's simplest to
> > use
> > - * the linux virq as the hardware interrupt number.
> > - */
> > -extern unsigned int irq_create_direct_mapping(struct irq_host *host);
> > -
> > -/**
> > - * irq_radix_revmap_insert - Insert a hw irq to linux virq number
> > mapping.
> > - * @host: host owning this hardware interrupt
> > - * @virq: linux irq number
> > - * @hwirq: hardware irq number in that host space
> > - *
> > - * This is for use by irq controllers that use a radix tree reverse
> > - * mapping for fast lookup.
> > - */
> > -extern void irq_radix_revmap_insert(struct irq_host *host, unsigned
> > int virq,
> > -				    irq_hw_number_t hwirq);
> > -
> > -/**
> > - * irq_radix_revmap_lookup - Find a linux virq from a hw irq number.
> > - * @host: host owning this hardware interrupt
> > - * @hwirq: hardware irq number in that host space
> > - *
> > - * This is a fast path, for use by irq controller code that uses radix
> > tree
> > - * revmaps
> > - */
> > -extern unsigned int irq_radix_revmap_lookup(struct irq_host *host,
> > -					    irq_hw_number_t hwirq);
> > -
> > -/**
> > - * irq_linear_revmap - Find a linux virq from a hw irq number.
> > - * @host: host owning this hardware interrupt
> > - * @hwirq: hardware irq number in that host space
> > - *
> > - * This is a fast path, for use by irq controller code that uses
> > linear
> > - * revmaps. It does fallback to the slow path if the revmap doesn't
> > exist
> > - * yet and will create the revmap entry with appropriate locking
> > - */
> > -
> > -extern unsigned int irq_linear_revmap(struct irq_host *host,
> > -				      irq_hw_number_t hwirq);
> > -
> > -
> > -
> > -/**
> > - * irq_alloc_virt - Allocate virtual irq numbers
> > - * @host: host owning these new virtual irqs
> > - * @count: number of consecutive numbers to allocate
> > - * @hint: pass a hint number, the allocator will try to use a 1:1
> > mapping
> > - *
> > - * This is a low level function that is used internally by
> > irq_create_mapping()
> > - * and that can be used by some irq controllers implementations for
> > things
> > - * like allocating ranges of numbers for MSIs. The revmaps are left
> > untouched.
> > - */
> > -extern unsigned int irq_alloc_virt(struct irq_host *host,
> > -				   unsigned int count,
> > -				   unsigned int hint);
> > -
> > -/**
> > - * irq_free_virt - Free virtual irq numbers
> > - * @virq: virtual irq number of the first interrupt to free
> > - * @count: number of interrupts to free
> > - *
> > - * This function is the opposite of irq_alloc_virt. It will not clear
> > reverse
> > - * maps, this should be done previously by unmap'ing the interrupt. In
> > fact,
> > - * all interrupts covered by the range being freed should have been
> > unmapped
> > - * prior to calling this.
> > - */
> > -extern void irq_free_virt(unsigned int virq, unsigned int count);
> > -
> > -/**
> > - * irq_early_init - Init irq remapping subsystem
> > - */
> > -extern void irq_early_init(void);
> > -
> >  static __inline__ int irq_canonicalize(int irq)
> >  {
> >  	return irq;
> > @@ -342,5 +74,7 @@ extern int call_handle_irq(int irq, void *p1,
> >  			   struct thread_info *tp, void *func);
> >  extern void do_IRQ(struct pt_regs *regs);
> > 
> > +#include <linux/virq.h>
> > +
> >  #endif /* _ASM_IRQ_H */
> >  #endif /* __KERNEL__ */
> > diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
> > index 4a65386..86d8e42 100644
> > --- a/arch/powerpc/kernel/irq.c
> > +++ b/arch/powerpc/kernel/irq.c
> > @@ -523,553 +523,6 @@ void do_softirq(void)
> >  }
> > 
> > 
> > -/*
> > - * IRQ controller and virtual interrupts
> > - */
> > -
> > -static LIST_HEAD(irq_hosts);
> > -static DEFINE_RAW_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;
> > -
> > -	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);
> > -			/* 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);
> > -	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();
> > -
> > -			/* Clear norequest flags */
> > -			irq_to_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...
> > -	 */
> > -	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)
> > -{
> > -	struct irq_desc *desc;
> > -
> > -	desc = irq_to_desc_alloc_node(virq, 0);
> > -	if (!desc) {
> > -		pr_debug("irq: -> allocating desc failed\n");
> > -		goto error;
> > -	}
> > -
> > -	/* Clear IRQ_NOREQUEST flag */
> > -	desc->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");
> > -		goto error;
> > -	}
> > -
> > -	return 0;
> > -
> > -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 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,
> > -				   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 != (irq_to_desc(virq)->status & IRQF_TRIGGER_MASK))
> > -		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;
> > -	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 */
> > -	irq_to_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;
> > -
> > -	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);
> > -
> > -	raw_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;
> > -	}
> > -	raw_spin_unlock_irqrestore(&irq_big_lock, flags);
> > -}
> > -
> >  int arch_early_irq_init(void)
> >  {
> >  	struct irq_desc *desc;
> > @@ -1090,118 +543,6 @@ int arch_init_chip_data(struct irq_desc *desc,
> > int node)
> >  	return 0;
> >  }
> > 
> > -/* 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 = irq_to_desc(i);
> > -		if (!desc)
> > -			continue;
> > -
> > -		raw_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->name)
> > -				p = desc->chip->name;
> > -			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);
> > -		}
> > -
> > -		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)
> >  {
> > diff --git a/include/linux/virq.h b/include/linux/virq.h
> > new file mode 100644
> > index 0000000..06035ef
> > --- /dev/null
> > +++ b/include/linux/virq.h
> > @@ -0,0 +1,302 @@
> > +/*
> > + * Virtual IRQ infrastructure
> > + *
> > + * Virtual IRQs provides support for dynamically allocating ranges of
> > IRQ
> > + * numbers for use by interrupt controllers.
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of version 2 of the GNU General Public
> > + * License as published by the Free Software Foundation.
> > + */
> > +
> > +
> > +#ifdef __KERNEL__
> > +#ifndef _LINUX_VIRQ_H
> > +#define _LINUX_VIRQ_H
> > +
> > +#include <asm/irq.h>
> > +
> > +#ifdef CONFIG_VIRQ
> > +
> > +/* Define a way to iterate across irqs. */
> > +#define for_each_irq(i) \
> > +	for ((i) = 0; (i) < NR_IRQS; ++(i))
> > +
> > +/* This type is the placeholder for a hardware interrupt number. It
> > has to
> > + * be big enough to enclose whatever representation is used by a given
> > + * platform.
> > + */
> > +typedef unsigned long irq_hw_number_t;
> > +
> > +/* Interrupt controller "host" data structure. This could be defined
> > as a
> > + * irq domain controller. That is, it handles the mapping between
> > hardware
> > + * and virtual interrupt numbers for a given interrupt domain. The
> > host
> > + * structure is generally created by the PIC code for a given PIC
> > instance
> > + * (though a host can cover more than one PIC if they have a flat
> > number
> > + * model). It's the host callbacks that are responsible for setting
> > the
> > + * irq_chip on a given irq_desc after it's been mapped.
> > + *
> > + * The host code and data structures are fairly agnostic to the fact
> > that
> > + * we use an open firmware device-tree. We do have references to
> > struct
> > + * device_node in two places: in irq_find_host() to find the host
> > matching
> > + * a given interrupt controller node, and of course as an argument to
> > its
> > + * counterpart host->ops->match() callback. However, those are treated
> > as
> > + * generic pointers by the core and the fact that it's actually a
> > device-node
> > + * pointer is purely a convention between callers and implementation.
> > This
> > + * code could thus be used on other architectures by replacing those
> > two
> > + * by some sort of arch-specific void * "token" used to identify
> > interrupt
> > + * controllers.
> > + */
> > +struct irq_host;
> > +struct radix_tree_root;
> > +struct device_node;
> > +
> > +/**
> > + * struct irq_host_ops - operations for managing per-domain hw irq
> > numbers
> > + *
> > + * Functions below are provided by the host and called whenever a new
> > mapping
> > + * is created or an old mapping is disposed. The host can then proceed
> > to
> > + * whatever internal data structures management is required. It also
> > needs
> > + * to setup the irq_desc when returning from map().
> > + */
> > +struct irq_host_ops {
> > +	/* Match an interrupt controller device node to a host, returns
> > +	 * 1 on a match
> > +	 */
> > +	int (*match)(struct irq_host *h, struct device_node *node);
> > +
> > +	/* Create or update a mapping between a virtual irq number and a
> > hw
> > +	 * irq number. This is called only once for a given mapping.
> > +	 */
> > +	int (*map)(struct irq_host *h, unsigned int virq, irq_hw_number_t
> > hw);
> > +
> > +	/* Dispose of such a mapping */
> > +	void (*unmap)(struct irq_host *h, unsigned int virq);
> > +
> > +	/* Update of such a mapping  */
> > +	void (*remap)(struct irq_host *h, unsigned int virq,
> > irq_hw_number_t hw);
> > +
> > +	/* Translate device-tree interrupt specifier from raw format
> > coming
> > +	 * from the firmware to a irq_hw_number_t (interrupt line number)
> > and
> > +	 * type (sense) that can be passed to set_irq_type(). In the
> > absence
> > +	 * of this callback, irq_create_of_mapping() and
> > irq_of_parse_and_map()
> > +	 * will return the hw number in the first cell and IRQ_TYPE_NONE
> > for
> > +	 * the type (which amount to keeping whatever default value the
> > +	 * interrupt controller has for that line)
> > +	 */
> > +	int (*xlate)(struct irq_host *h, struct device_node *ctrler,
> > +		     const u32 *intspec, unsigned int intsize,
> > +		     irq_hw_number_t *out_hwirq, unsigned int *out_type);
> > +};
> > +
> > +/**
> > + * struct irq_host - a single irq domain. maps hw irq numbers to Linux
> > irq.
> > + * @link: entry in global irq_host list
> > + * @revmap_type: Method of reverse mapping hwirq to Linux irq number
> > + * @revmap_data: reverse map data
> > + * @ops: irq domain operations (documented above)
> > + * @host_data: irq controller driver data; core does not touch this
> > pointer
> > + * @inval_irq: hw irq number used for unassigned virqs
> > + * @of_node: Optional pointer to the irq controllers device tree node.
> > + *
> > + * One irq_host is allocated for each range (domain) of Linux irq
> > numbers
> > + * allocated.  Typically, one irq_host is allocated per controller,
> > but it
> > + * is perfectly valid to manage multiple controllers with a single
> > irq_host
> > + * instance if need be.
> > + */
> > +struct irq_host {
> > +	struct list_head	link;
> > +
> > +	/* type of reverse mapping technique */
> > +	unsigned int		revmap_type;
> > +#define IRQ_HOST_MAP_LEGACY     0 /* legacy 8259, gets irqs 1..15 */
> > +#define IRQ_HOST_MAP_NOMAP	1 /* no fast reverse mapping */
> > +#define IRQ_HOST_MAP_LINEAR	2 /* linear map of interrupts */
> > +#define IRQ_HOST_MAP_TREE	3 /* radix tree */
> > +	union {
> > +		struct {
> > +			unsigned int size;
> > +			unsigned int *revmap;
> > +		} linear;
> > +		struct radix_tree_root tree;
> > +	} revmap_data;
> > +	struct irq_host_ops	*ops;
> > +	void			*host_data;
> > +	irq_hw_number_t		inval_irq;
> > +
> > +	/* Optional device node pointer */
> > +	struct device_node	*of_node;
> > +};
> > +
> > +/**
> > + * irq_alloc_host() - Allocate a new irq_host data structure
> > + * @of_node: optional device-tree node of the interrupt controller
> > + * @revmap_type: type of reverse mapping to use
> > + * @revmap_arg: for IRQ_HOST_MAP_LINEAR linear only: size of the map
> > + * @ops: map/unmap host callbacks
> > + * @inval_irq: provide a hw number in that host space that is always
> > invalid
> > + *
> > + * Allocates and initialize and irq_host structure. Note that in the
> > case of
> > + * IRQ_HOST_MAP_LEGACY, the map() callback will be called before this
> > returns
> > + * for all legacy interrupts except 0 (which is always the invalid irq
> > for
> > + * a legacy controller). For a IRQ_HOST_MAP_LINEAR, the map is
> > allocated by
> > + * this call as well. For a IRQ_HOST_MAP_TREE, the radix tree will be
> > allocated
> > + * later during boot automatically (the reverse mapping will use the
> > slow path
> > + * until that happens).
> > + */
> > +extern 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);
> > +
> > +/* 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;
> > +};
> > +extern struct irq_map_entry irq_map[NR_IRQS];
> > +
> > +extern irq_hw_number_t virq_to_hw(unsigned int virq);
> > +
> > +/**
> > + * irq_find_host - Locates a host for a given device node
> > + * @node: device-tree node of the interrupt controller
> > + */
> > +extern struct irq_host *irq_find_host(struct device_node *node);
> > +
> > +/**
> > + * irq_set_default_host - Set a "default" host
> > + * @host: default host pointer
> > + *
> > + * For convenience, it's possible to set a "default" host that will be
> > used
> > + * whenever NULL is passed to irq_create_mapping(). It makes life
> > easier for
> > + * platforms that want to manipulate a few hard coded interrupt
> > numbers that
> > + * aren't properly represented in the device-tree.
> > + */
> > +extern void irq_set_default_host(struct irq_host *host);
> > +
> > +/**
> > + * irq_set_virq_count - Set the maximum number of virt irqs
> > + * @count: number of linux virtual irqs, capped with NR_IRQS
> > + *
> > + * This is mainly for use by platforms like iSeries who want to
> > program
> > + * the virtual irq number in the controller to avoid the reverse
> > mapping
> > + */
> > +extern void irq_set_virq_count(unsigned int count);
> > +
> > +/**
> > + * irq_create_mapping - Map a hardware interrupt into linux virq space
> > + * @host: host owning this hardware interrupt or NULL for default host
> > + * @hwirq: hardware irq number in that host space
> > + *
> > + * Only one mapping per hardware interrupt is permitted. Returns a
> > linux
> > + * virq number.
> > + * If the sense/trigger is to be specified, set_irq_type() should be
> > called
> > + * on the number returned from that call.
> > + */
> > +extern unsigned int irq_create_mapping(struct irq_host *host,
> > +				       irq_hw_number_t hwirq);
> > +
> > +/**
> > + * irq_dispose_mapping - Unmap an interrupt
> > + * @virq: linux virq number of the interrupt to unmap
> > + */
> > +extern void irq_dispose_mapping(unsigned int virq);
> > +
> > +/**
> > + * irq_find_mapping - Find a linux virq from an hw irq number.
> > + * @host: host owning this hardware interrupt
> > + * @hwirq: hardware irq number in that host space
> > + *
> > + * This is a slow path, for use by generic code. It's expected that an
> > + * irq controller implementation directly calls the appropriate low
> > level
> > + * mapping function.
> > + */
> > +extern unsigned int irq_find_mapping(struct irq_host *host,
> > +				     irq_hw_number_t hwirq);
> > +
> > +/**
> > + * irq_create_direct_mapping - Allocate a virq for direct mapping
> > + * @host: host to allocate the virq for or NULL for default host
> > + *
> > + * This routine is used for irq controllers which can choose the
> > hardware
> > + * interrupt numbers they generate. In such a case it's simplest to
> > use
> > + * the linux virq as the hardware interrupt number.
> > + */
> > +extern unsigned int irq_create_direct_mapping(struct irq_host *host);
> > +
> > +/**
> > + * irq_radix_revmap_insert - Insert a hw irq to linux virq number
> > mapping.
> > + * @host: host owning this hardware interrupt
> > + * @virq: linux irq number
> > + * @hwirq: hardware irq number in that host space
> > + *
> > + * This is for use by irq controllers that use a radix tree reverse
> > + * mapping for fast lookup.
> > + */
> > +extern void irq_radix_revmap_insert(struct irq_host *host, unsigned
> > int virq,
> > +				    irq_hw_number_t hwirq);
> > +
> > +/**
> > + * irq_radix_revmap_lookup - Find a linux virq from a hw irq number.
> > + * @host: host owning this hardware interrupt
> > + * @hwirq: hardware irq number in that host space
> > + *
> > + * This is a fast path, for use by irq controller code that uses radix
> > tree
> > + * revmaps
> > + */
> > +extern unsigned int irq_radix_revmap_lookup(struct irq_host *host,
> > +					    irq_hw_number_t hwirq);
> > +
> > +/**
> > + * irq_linear_revmap - Find a linux virq from a hw irq number.
> > + * @host: host owning this hardware interrupt
> > + * @hwirq: hardware irq number in that host space
> > + *
> > + * This is a fast path, for use by irq controller code that uses
> > linear
> > + * revmaps. It does fallback to the slow path if the revmap doesn't
> > exist
> > + * yet and will create the revmap entry with appropriate locking
> > + */
> > +
> > +extern unsigned int irq_linear_revmap(struct irq_host *host,
> > +				      irq_hw_number_t hwirq);
> > +
> > +
> > +
> > +/**
> > + * irq_alloc_virt - Allocate virtual irq numbers
> > + * @host: host owning these new virtual irqs
> > + * @count: number of consecutive numbers to allocate
> > + * @hint: pass a hint number, the allocator will try to use a 1:1
> > mapping
> > + *
> > + * This is a low level function that is used internally by
> > irq_create_mapping()
> > + * and that can be used by some irq controllers implementations for
> > things
> > + * like allocating ranges of numbers for MSIs. The revmaps are left
> > untouched.
> > + */
> > +extern unsigned int irq_alloc_virt(struct irq_host *host,
> > +				   unsigned int count,
> > +				   unsigned int hint);
> > +
> > +/**
> > + * irq_free_virt - Free virtual irq numbers
> > + * @virq: virtual irq number of the first interrupt to free
> > + * @count: number of interrupts to free
> > + *
> > + * This function is the opposite of irq_alloc_virt. It will not clear
> > reverse
> > + * maps, this should be done previously by unmap'ing the interrupt. In
> > fact,
> > + * all interrupts covered by the range being freed should have been
> > unmapped
> > + * prior to calling this.
> > + */
> > +extern void irq_free_virt(unsigned int virq, unsigned int count);
> > +
> > +
> > +#endif /* CONFIG_VIRQ */
> > +
> > +#endif /* _LINUX_VIRQ_H */
> > +#endif /* __KERNEL__ */
> > +
> > diff --git a/kernel/irq/Makefile b/kernel/irq/Makefile
> > index 7d04780..f5207dc 100644
> > --- a/kernel/irq/Makefile
> > +++ b/kernel/irq/Makefile
> > @@ -1,5 +1,6 @@
> > 
> >  obj-y := handle.o manage.o spurious.o resend.o chip.o devres.o
> > +obj-$(CONFIG_VIRQ) += virq.o
> >  obj-$(CONFIG_GENERIC_IRQ_PROBE) += autoprobe.o
> >  obj-$(CONFIG_PROC_FS) += proc.o
> >  obj-$(CONFIG_GENERIC_PENDING_IRQ) += migration.o
> > diff --git a/kernel/irq/virq.c b/kernel/irq/virq.c
> > new file mode 100644
> > index 0000000..b3c0db3
> > --- /dev/null
> > +++ b/kernel/irq/virq.c
> > @@ -0,0 +1,687 @@
> > +/*
> > + * Mapping support from per-controller hw irq numbers to linux irqs
> > + *
> > + *  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 ([email-masked])
> > + *  Updated and modified by Cort Dougan <[email-masked]>
> > + *    Copyright (C) 1996-2001 Cort Dougan
> > + *  Adapted for Power Macintosh by Paul Mackerras
> > + *    Copyright (C) 1996 Paul Mackerras ([email-masked])
> > + *  Generalized for virtual irq mapping on all platformes by Grant
> > Likely
> > + *    Copyright (C) 2010 Secret Lab Technologies Ltd.
> > + *
> > + * 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.
> > + */
> > +
> > +#include <linux/interrupt.h>
> > +#include <linux/irq.h>
> > +#include <linux/module.h>
> > +#include <linux/mutex.h>
> > +#include <linux/slab.h>
> > +#include <linux/radix-tree.h>
> > +#include <linux/virq.h>
> > +#include <linux/of_irq.h>
> > +
> > +/*
> > + * IRQ controller and virtual interrupts
> > + */
> > +static LIST_HEAD(irq_hosts);
> > +static DEFINE_RAW_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;
> > +
> > +	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);
> > +			/* 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);
> > +	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();
> > +
> > +			/* Clear norequest flags */
> > +			irq_to_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...
> > +	 */
> > +	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)
> > +{
> > +	struct irq_desc *desc;
> > +
> > +	desc = irq_to_desc_alloc_node(virq, 0);
> > +	if (!desc) {
> > +		pr_debug("irq: -> allocating desc failed\n");
> > +		goto error;
> > +	}
> > +
> > +	/* Clear IRQ_NOREQUEST flag */
> > +	desc->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");
> > +		goto error;
> > +	}
> > +
> > +	return 0;
> > +
> > +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 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,
> > +				   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 != (irq_to_desc(virq)->status & IRQF_TRIGGER_MASK))
> > +		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;
> > +	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 */
> > +	irq_to_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;
> > +
> > +	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);
> > +
> > +	raw_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;
> > +	}
> > +	raw_spin_unlock_irqrestore(&irq_big_lock, flags);
> > +}
> > +
> > +/* 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 = irq_to_desc(i);
> > +		if (!desc)
> > +			continue;
> > +
> > +		raw_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->name)
> > +				p = desc->chip->name;
> > +			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);
> > +		}
> > +
> > +		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 */
> > +
> > 
> > _______________________________________________
> > devicetree-discuss mailing list
> > [email-masked]
> > https://lists.ozlabs.org/listinfo/devicetree-discuss
>