genirq: Allow the PM device to originate from irq domain

As a preparation to moving the reference to the device used for
runtime power management, add a new 'dev' field to the irqdomain
structure for that exact purpose.

The irq_chip_pm_{get,put}() helpers are made aware of the dual
location via a new private helper.

No functional change intended.

Signed-off-by: Marc Zyngier <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Tested-by: Geert Uytterhoeven <[e-mail]>
Tested-by: Tony Lindgren <[e-mail]>
Acked-by: Bartosz Golaszewski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

include/linux/irqdomain.h

···
  * @gc: Pointer to a list of generic chips. There is a helper function for
  *      setting up one or more generic chips for interrupt controllers
  *      drivers using the generic chip library which uses this pointer.
+ * @dev: Pointer to a device that the domain represent, and that will be
+ *       used for power management purposes.
  * @parent: Pointer to parent irq_domain to support hierarchy irq_domains
  *
  * Revmap data, used internally by irq_domain
···
 	struct fwnode_handle *fwnode;
 	enum irq_domain_bus_token bus_token;
 	struct irq_domain_chip_generic *gc;
+	struct device *dev;
 #ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
 	struct irq_domain *parent;
 #endif
···
 static inline struct device_node *irq_domain_get_of_node(struct irq_domain *d)
 {
 	return to_of_node(d->fwnode);
+}
+
+static inline void irq_domain_set_pm_device(struct irq_domain *d,
+					    struct device *dev)
+{
+	if (d)
+		d->dev = dev;
 }
 
 #ifdef CONFIG_IRQ_DOMAIN

kernel/irq/chip.c

···
 	return 0;
 }
 
+static struct device *irq_get_parent_device(struct irq_data *data)
+{
+	if (data->chip->parent_device)
+		return data->chip->parent_device;
+
+	if (data->domain)
+		return data->domain->dev;
+
+	return NULL;
+}
+
 /**
  * irq_chip_pm_get - Enable power for an IRQ chip
  * @data:	Pointer to interrupt specific data
···
  */
 int irq_chip_pm_get(struct irq_data *data)
 {
+	struct device *dev = irq_get_parent_device(data);
 	int retval;
 
-	if (IS_ENABLED(CONFIG_PM) && data->chip->parent_device) {
-		retval = pm_runtime_get_sync(data->chip->parent_device);
+	if (IS_ENABLED(CONFIG_PM) && dev) {
+		retval = pm_runtime_get_sync(dev);
 		if (retval < 0) {
-			pm_runtime_put_noidle(data->chip->parent_device);
+			pm_runtime_put_noidle(dev);
 			return retval;
 		}
 	}
···
  */
 int irq_chip_pm_put(struct irq_data *data)
 {
+	struct device *dev = irq_get_parent_device(data);
 	int retval = 0;
 
-	if (IS_ENABLED(CONFIG_PM) && data->chip->parent_device)
-		retval = pm_runtime_put(data->chip->parent_device);
+	if (IS_ENABLED(CONFIG_PM) && dev)
+		retval = pm_runtime_put(dev);
 
 	return (retval < 0) ? retval : 0;
 }