genirq/msi: Provide MSI_FLAG_PARENT_PM_DEV

Some platform-MSI implementations require that power management is
redirected to the underlying interrupt chip device. To make this work
with per device MSI domains provide a new feature flag and let the
core code handle the setup of dev->pm_dev when set during device MSI
domain creation.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240127161753.114685-14-apatel@ventanamicro.com

include/linux/msi.h

@@ -554,6 +554,8 @@ enum {
 	MSI_FLAG_FREE_MSI_DESCS		= (1 << 6),
 	/* Use dev->fwnode for MSI device domain creation */
 	MSI_FLAG_USE_DEV_FWNODE		= (1 << 7),
+	/* Set parent->dev into domain->pm_dev on device domain creation */
+	MSI_FLAG_PARENT_PM_DEV		= (1 << 8),
 
 	/* Mask for the generic functionality */
 	MSI_GENERIC_FLAGS_MASK		= GENMASK(15, 0),

kernel/irq/msi.c

@@ -845,8 +845,11 @@ static struct irq_domain *__msi_create_irq_domain(struct fwnode_handle *fwnode,
 	domain = irq_domain_create_hierarchy(parent, flags | IRQ_DOMAIN_FLAG_MSI, 0,
 					     fwnode, &msi_domain_ops, info);
 
-	if (domain)
+	if (domain) {
 		irq_domain_update_bus_token(domain, info->bus_token);
+		if (info->flags & MSI_FLAG_PARENT_PM_DEV)
+			domain->pm_dev = parent->pm_dev;
+	}
 
 	return domain;
 }