+/* Number of irqs reserved for the legacy controller */
+#define NUM_ISA_INTERRUPTS 16
+
+/* 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 can be called several times for the same mapping
+ * but with different flags, though unmap shall always be called
+ * before the virq->hw mapping is changed.
+ */
+ int (*map)(struct irq_host *h, unsigned int virq,
+ irq_hw_number_t hw, unsigned int flags);
+
+ /* Dispose of such a mapping */
+ void (*unmap)(struct irq_host *h, unsigned int virq);
+
+ /* Translate device-tree interrupt specifier from raw format coming
+ * from the firmware to a irq_hw_number_t (interrupt line number) and
+ * trigger flags that can be passed to irq_create_mapping().
+ * If no translation is provided, raw format is assumed to be one cell
+ * for interrupt line and default sense.
+ */
+ int (*xlate)(struct irq_host *h, struct device_node *ctrler,
+ u32 *intspec, unsigned int intsize,
+ irq_hw_number_t *out_hwirq, unsigned int *out_flags);
+};
+
+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;
+};
+
+/* 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];
+
+
+/***
+ * irq_alloc_host - Allocate a new irq_host data structure
+ * @node: 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(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
+ * @flags: flags passed to the controller. contains the trigger type among
+ * others. Use IRQ_TYPE_* defined in include/linux/irq.h
+ *
+ * Only one mapping per hardware interrupt is permitted. Returns a linux
+ * virq number. The flags can be used to provide sense information to the
+ * controller (typically extracted from the device-tree). If no information
+ * is passed, the controller defaults will apply (for example, xics can only
+ * do edge so flags are irrelevant for some pseries specific irqs).
+ *
+ * The device-tree generally contains the trigger info in an encoding that is
+ * specific to a given type of controller. In that case, you can directly use
+ * host->ops->trigger_xlate() to translate that.
+ *
+ * It is recommended that new PICs that don't have existing OF bindings chose
+ * to use a representation of triggers identical to linux.
+ */
+extern unsigned int irq_create_mapping(struct irq_host *host,
+ irq_hw_number_t hwirq,
+ unsigned int flags);
+
+
+/***
+ * 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_radix_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 radix tree
+ * revmaps