[PATCH 1/2] irqdomain: Allow giving name suffix for domain

[Matti Vaittinen <mazziesaccount@gmail.com>]

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Devices can provide multiple interrupt lines. One reason for this is that
a device has multiple subfunctions, each providing its own interrupt line.
Another reason is that a device can be designed to be used (also) on a
system where some of the interrupts can be routed to another processor.

A line often further acts as a demultiplex for specific interrupts
and has it's respective set of interrupt (status, mask, ack, ...)
registers.

Regmap supports the handling of these registers and demultiplexing
interrupts, but interrupt domain code ends up assigning the same name for
the per interrupt line domains. This will cause a naming collision in the
debugFS code and can also lead to confusion, as /proc/interrupts would
show two separate interrupts with the same domain name and hardware
interrupt number.

Instead of adding a workaround in regmap or driver code, allow giving a
name suffix for the domain name when the domain is created.

Add a name_suffix field in the irq_domain_info structure and make the
irq_domain_instantiate() to use this suffix if it is given when a domain
is created.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
---
 include/linux/irqdomain.h |  3 +++
 kernel/irq/irqdomain.c    | 36 +++++++++++++++++++++++++++---------
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 02cd486ac354..77ead0d41ccd 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -274,6 +274,8 @@ struct irq_domain_chip_generic_info;
  * @direct_max:		Maximum value of direct maps;
  *			Use ~0 for no limit; 0 for no direct mapping
  * @bus_token:		Domain bus token
+ * @name_suffix:	Optional name suffix to avoid collisions when multiple
+ *			domains are added using same fwnode
  * @ops:		Domain operation callbacks
  * @host_data:		Controller private data pointer
  * @dgc_info:		Geneneric chip information structure pointer used to
@@ -290,6 +292,7 @@ struct irq_domain_info {
 	irq_hw_number_t				hwirq_max;
 	int					direct_max;
 	enum irq_domain_bus_token		bus_token;
+	const char				*name_suffix;
 	const struct irq_domain_ops		*ops;
 	void					*host_data;
 #ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 91eaf6bfcbf0..41348a325a94 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -129,13 +129,25 @@ void irq_domain_free_fwnode(struct fwnode_handle *fwnode)
 EXPORT_SYMBOL_GPL(irq_domain_free_fwnode);
 
 static int irq_domain_set_name(struct irq_domain *domain,
-			       const struct fwnode_handle *fwnode,
-			       enum irq_domain_bus_token bus_token)
+			       const struct irq_domain_info *info)
 {
+	const struct fwnode_handle *fwnode = info->fwnode;
+	enum irq_domain_bus_token bus_token = info->bus_token;
 	static atomic_t unknown_domains;
 	struct irqchip_fwid *fwid;
 
 	if (is_fwnode_irqchip(fwnode)) {
+		/*
+		 * The name_suffix is only intended to be used to avoid a name
+		 * collison, when multiple domains are created for a single
+		 * device and the name is picked using a real device node.
+		 * (Typical use-case is regmap-IRQ controllers for devices
+		 * providing more than one physical IRQ.) There should be no
+		 * need to use name_suffix with irqchip-fwnode.
+		 */
+		if (info->name_suffix)
+			return NULL;
+
 		fwid = container_of(fwnode, struct irqchip_fwid, fwnode);
 
 		switch (fwid->type) {
@@ -164,17 +176,23 @@ static int irq_domain_set_name(struct irq_domain *domain,
 		   is_software_node(fwnode)) {
 		char *name;
 
+		if (info->name_suffix)
+			name = bus_token ?
+				kasprintf(GFP_KERNEL, "%pfw-%s-%d", fwnode,
+					  info->name_suffix, bus_token) :
+				kasprintf(GFP_KERNEL, "%pfw-%s", fwnode, info->name_suffix);
+		else
+			name = bus_token ?
+				kasprintf(GFP_KERNEL, "%pfw-%d", fwnode, bus_token) :
+				kasprintf(GFP_KERNEL, "%pfw", fwnode);
+		if (!name)
+			return -ENOMEM;
+
 		/*
 		 * fwnode paths contain '/', which debugfs is legitimately
 		 * unhappy about. Replace them with ':', which does
 		 * the trick and is not as offensive as '\'...
 		 */
-		name = bus_token ?
-			kasprintf(GFP_KERNEL, "%pfw-%d", fwnode, bus_token) :
-			kasprintf(GFP_KERNEL, "%pfw", fwnode);
-		if (!name)
-			return -ENOMEM;
-
 		domain->name = strreplace(name, '/', ':');
 		domain->flags |= IRQ_DOMAIN_NAME_ALLOCATED;
 	}
@@ -211,7 +229,7 @@ static struct irq_domain *__irq_domain_create(const struct irq_domain_info *info
 	if (!domain)
 		return ERR_PTR(-ENOMEM);
 
-	err = irq_domain_set_name(domain, info->fwnode, info->bus_token);
+	err = irq_domain_set_name(domain, info);
 	if (err) {
 		kfree(domain);
 		return ERR_PTR(err);
-- 
2.45.1


-- 
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
Simon says - in Latin please.
~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
Thanks to Simon Glass for the translation =] 

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