[PATCH v2 10/19] irqdomain: Introduce irq_domain_alloc() and irq_domain_publish()

[Herve Codina]

The irq_domain_add_*() family functions create an irq_domain and also
publish this newly created to domain. Once an irq_domain is published,
consumers can request IRQ in order to use them.

Some interrupt controller drivers have to perform some more operations
with the created irq_domain in order to have it ready to be used.
For instance:
  - Allocate generic irq chips with irq_alloc_domain_generic_chips()
  - Retrieve the generic irq chips with irq_get_domain_generic_chip()
  - Initialize retrieved chips: set register base address and offsets,
    set several hooks such as irq_mask, irq_unmask, ...

To avoid a window where the domain is published but not yet ready to be
used, introduce irq_domain_alloc_*() family functions to create the
irq_domain and irq_domain_publish() to publish the irq_domain.
With this new functions, any additional initialisation can then be done
between the call creating the irq_domain and the call publishing it.

Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
---
 include/linux/irqdomain.h | 16 +++++++
 kernel/irq/irqdomain.c    | 91 ++++++++++++++++++++++++++++-----------
 2 files changed, 82 insertions(+), 25 deletions(-)

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 21ecf582a0fe..86203e7e6659 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -257,6 +257,22 @@ static inline struct fwnode_handle *irq_domain_alloc_fwnode(phys_addr_t *pa)
 }
 
 void irq_domain_free_fwnode(struct fwnode_handle *fwnode);
+struct irq_domain *irq_domain_alloc(struct fwnode_handle *fwnode, unsigned int size,
+				    irq_hw_number_t hwirq_max, int direct_max,
+				    const struct irq_domain_ops *ops,
+				    void *host_data);
+
+static inline struct irq_domain *irq_domain_alloc_linear(struct fwnode_handle *fwnode,
+							 unsigned int size,
+							 const struct irq_domain_ops *ops,
+							 void *host_data)
+{
+	return irq_domain_alloc(fwnode, size, size, 0, ops, host_data);
+}
+
+void irq_domain_free(struct irq_domain *domain);
+void irq_domain_publish(struct irq_domain *domain);
+void irq_domain_unpublish(struct irq_domain *domain);
 struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, unsigned int size,
 				    irq_hw_number_t hwirq_max, int direct_max,
 				    const struct irq_domain_ops *ops,
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 86f8b91b0d3a..06c3e1b03a1d 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -231,7 +231,38 @@ static struct irq_domain *__irq_domain_create(struct fwnode_handle *fwnode,
 	return domain;
 }
 
-static void __irq_domain_publish(struct irq_domain *domain)
+struct irq_domain *irq_domain_alloc(struct fwnode_handle *fwnode, unsigned int size,
+				    irq_hw_number_t hwirq_max, int direct_max,
+				    const struct irq_domain_ops *ops,
+				    void *host_data)
+{
+	return __irq_domain_create(fwnode, size, hwirq_max, direct_max, ops,
+				   host_data);
+}
+EXPORT_SYMBOL_GPL(irq_domain_alloc);
+
+/**
+ * irq_domain_free() - Free an irq domain.
+ * @domain: domain to free
+ *
+ * This routine is used to free an irq domain. The caller must ensure
+ * that the domain is not published.
+ */
+void irq_domain_free(struct irq_domain *domain)
+{
+	fwnode_dev_initialized(domain->fwnode, false);
+	fwnode_handle_put(domain->fwnode);
+	if (domain->flags & IRQ_DOMAIN_NAME_ALLOCATED)
+		kfree(domain->name);
+	kfree(domain);
+}
+EXPORT_SYMBOL_GPL(irq_domain_free);
+
+/**
+ * irq_domain_publish() - Publish an irq domain.
+ * @domain: domain to publish
+ */
+void irq_domain_publish(struct irq_domain *domain)
 {
 	mutex_lock(&irq_domain_mutex);
 	debugfs_add_domain_dir(domain);
@@ -240,6 +271,36 @@ static void __irq_domain_publish(struct irq_domain *domain)
 
 	pr_debug("Added domain %s\n", domain->name);
 }
+EXPORT_SYMBOL_GPL(irq_domain_publish);
+
+/**
+ * irq_domain_unpublish() - Unpublish an irq domain.
+ * @domain: domain to unpublish
+ *
+ * This routine is used to unpublish an irq domain. The caller must ensure
+ * that all mappings within the domain have been disposed of prior to
+ * use, depending on the revmap type.
+ */
+void irq_domain_unpublish(struct irq_domain *domain)
+{
+	mutex_lock(&irq_domain_mutex);
+	debugfs_remove_domain_dir(domain);
+
+	WARN_ON(!radix_tree_empty(&domain->revmap_tree));
+
+	list_del(&domain->link);
+
+	/*
+	 * If the going away domain is the default one, reset it.
+	 */
+	if (unlikely(irq_default_domain == domain))
+		irq_set_default_host(NULL);
+
+	mutex_unlock(&irq_domain_mutex);
+
+	pr_debug("Removed domain %s\n", domain->name);
+}
+EXPORT_SYMBOL_GPL(irq_domain_unpublish);
 
 /**
  * __irq_domain_add() - Allocate a new irq_domain data structure
@@ -264,7 +325,7 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, unsigned int s
 	domain = __irq_domain_create(fwnode, size, hwirq_max, direct_max,
 				     ops, host_data);
 	if (domain)
-		__irq_domain_publish(domain);
+		irq_domain_publish(domain);
 
 	return domain;
 }
@@ -280,28 +341,8 @@ EXPORT_SYMBOL_GPL(__irq_domain_add);
  */
 void irq_domain_remove(struct irq_domain *domain)
 {
-	mutex_lock(&irq_domain_mutex);
-	debugfs_remove_domain_dir(domain);
-
-	WARN_ON(!radix_tree_empty(&domain->revmap_tree));
-
-	list_del(&domain->link);
-
-	/*
-	 * If the going away domain is the default one, reset it.
-	 */
-	if (unlikely(irq_default_domain == domain))
-		irq_set_default_host(NULL);
-
-	mutex_unlock(&irq_domain_mutex);
-
-	pr_debug("Removed domain %s\n", domain->name);
-
-	fwnode_dev_initialized(domain->fwnode, false);
-	fwnode_handle_put(domain->fwnode);
-	if (domain->flags & IRQ_DOMAIN_NAME_ALLOCATED)
-		kfree(domain->name);
-	kfree(domain);
+	irq_domain_unpublish(domain);
+	irq_domain_free(domain);
 }
 EXPORT_SYMBOL_GPL(irq_domain_remove);
 
@@ -1184,7 +1225,7 @@ struct irq_domain *irq_domain_create_hierarchy(struct irq_domain *parent,
 		domain->parent = parent;
 		domain->flags |= flags;
 
-		__irq_domain_publish(domain);
+		irq_domain_publish(domain);
 	}
 
 	return domain;
-- 
2.45.0