From: Marc Zyngier <marc.zyngier@arm.com>
Date: Thu, 22 Jun 2017 11:34:57 +0100
Subject: genirq/irqdomain: Add irq_domain_update_bus_token helper
Patch-mainline: v4.13-rc1
Git-commit: 61d0a000b7746665c7cfcff766532f6f2a922a61
References: FATE#323954

We can have irq domains that are identified by the same fwnode
(because they are serviced by the same HW), and yet have different
functionnality (because they serve different busses, for example).
This is what we use the bus_token field.

Since we don't use this field when generating the domain name,
all the aliasing domains will get the same name, and the debugfs
file creation fails. Also, bus_token is updated by individual drivers,
and the core code is unaware of that update.

In order to sort this mess, let's introduce a helper that takes care
of updating bus_token, and regenerate the debugfs file.

A separate patch will update all the individual users.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Alexander Graf <agraf@suse.de>
---
 include/linux/irqdomain.h |    3 +++
 kernel/irq/irqdomain.c    |   33 +++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -238,6 +238,9 @@
 	return fwnode && fwnode->type == FWNODE_IRQCHIP;
 }
 
+extern void irq_domain_update_bus_token(struct irq_domain *domain,
+					enum irq_domain_bus_token bus_token);
+
 static inline
 struct irq_domain *irq_find_matching_fwnode(struct fwnode_handle *fwnode,
 					    enum irq_domain_bus_token bus_token)
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -156,6 +156,39 @@
 }
 EXPORT_SYMBOL_GPL(irq_domain_remove);
 
+void irq_domain_update_bus_token(struct irq_domain *domain,
+				 enum irq_domain_bus_token bus_token)
+{
+	char *name;
+
+	if (domain->bus_token == bus_token)
+		return;
+
+	mutex_lock(&irq_domain_mutex);
+
+	domain->bus_token = bus_token;
+
+	name = kasprintf(GFP_KERNEL, "%s-%d", domain->name, bus_token);
+	if (!name) {
+		mutex_unlock(&irq_domain_mutex);
+		return;
+	}
+
+	/* agraf@suse.com: Skip as domain dirs are not backported */
+	/* debugfs_remove_domain_dir(domain); */
+
+	if (domain->flags & IRQ_DOMAIN_NAME_ALLOCATED)
+		kfree(domain->name);
+	else
+		domain->flags |= IRQ_DOMAIN_NAME_ALLOCATED;
+
+	domain->name = name;
+	/* agraf@suse.com: Skip as domain dirs are not backported */
+	/* debugfs_add_domain_dir(domain); */
+
+	mutex_unlock(&irq_domain_mutex);
+}
+
 /**
  * irq_domain_add_simple() - Register an irq_domain and optionally map a range of irqs
  * @of_node: pointer to interrupt controller's device tree node.