irqdomain: Introduce helper function irq_domain_add_hierarchy()

Introduce helper function irq_domain_add_hierarchy(), which creates
a linear irqdomain if parameter 'size' is not zero, otherwise creates
a tree irqdomain.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Yijing Wang <wangyijing@huawei.com>
Cc: Yingjoe Chen <yingjoe.chen@mediatek.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Link: http://lkml.kernel.org/r/1416061447-9472-5-git-send-email-jiang.liu@linux.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/irqdomain.h

@@ -259,6 +259,10 @@ int irq_domain_xlate_onetwocell(struct irq_domain *d, struct device_node *ctrlr,
 extern struct irq_data *irq_domain_get_irq_data(struct irq_domain *domain,
 						unsigned int virq);
 #ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
+extern struct irq_domain *irq_domain_add_hierarchy(struct irq_domain *parent,
+			unsigned int flags, unsigned int size,
+			struct device_node *node,
+			const struct irq_domain_ops *ops, void *host_data);
 extern int __irq_domain_alloc_irqs(struct irq_domain *domain, int irq_base,
 				   unsigned int nr_irqs, int node, void *arg,
 				   bool realloc);

kernel/irq/irqdomain.c

@@ -742,6 +742,42 @@ static int irq_domain_alloc_descs(int virq, unsigned int cnt,
 }
 
 #ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
+/**
+ * irq_domain_add_hierarchy - Add a irqdomain into the hierarchy
+ * @parent:	Parent irq domain to associate with the new domain
+ * @flags:	Irq domain flags associated to the domain
+ * @size:	Size of the domain. See below
+ * @node:	Optional device-tree node of the interrupt controller
+ * @ops:	Pointer to the interrupt domain callbacks
+ * @host_data:	Controller private data pointer
+ *
+ * If @size is 0 a tree domain is created, otherwise a linear domain.
+ *
+ * If successful the parent is associated to the new domain and the
+ * domain flags are set.
+ * Returns pointer to IRQ domain, or NULL on failure.
+ */
+struct irq_domain *irq_domain_add_hierarchy(struct irq_domain *parent,
+					    unsigned int flags,
+					    unsigned int size,
+					    struct device_node *node,
+					    const struct irq_domain_ops *ops,
+					    void *host_data)
+{
+	struct irq_domain *domain;
+
+	if (size)
+		domain = irq_domain_add_linear(node, size, ops, host_data);
+	else
+		domain = irq_domain_add_tree(node, ops, host_data);
+	if (domain) {
+		domain->parent = parent;
+		domain->flags |= flags;
+	}
+
+	return domain;
+}
+
 static void irq_domain_insert_irq(int virq)
 {
 	struct irq_data *data;