irqchip/msi-lib: Add IRQ_DOMAIN_FLAG_FWNODE_PARENT handling

In some irqchip implementations the fwnode representing the IRQdomain
and the MSI controller fwnode do not match; in particular the IRQdomain
fwnode is the MSI controller fwnode parent.

To support selecting such IRQ domains, add a flag in core IRQ domain
code that explicitly tells the MSI lib to use the parent fwnode while
carrying out IRQ domain selection.

Update the msi-lib select callback with the resulting logic.

Signed-off-by: Lorenzo Pieralisi <[email protected]>
Reviewed-by: Marc Zyngier <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Marc Zyngier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Marc Zyngier <[email protected]>

Author: Lorenzo Pieralisi

drivers/irqchip/irq-msi-lib.c

@@ -133,11 +133,14 @@ int msi_lib_irq_domain_select(struct irq_domain *d, struct irq_fwspec *fwspec,
 {
 	const struct msi_parent_ops *ops = d->msi_parent_ops;
 	u32 busmask = BIT(bus_token);
+	struct fwnode_handle *fwh;
 
 	if (!ops)
 		return 0;
 
-	if (fwspec->fwnode != d->fwnode || fwspec->param_count != 0)
+	fwh = d->flags & IRQ_DOMAIN_FLAG_FWNODE_PARENT ? fwnode_get_parent(fwspec->fwnode)
+						       : fwspec->fwnode;
+	if (fwh != d->fwnode || fwspec->param_count != 0)
 		return 0;
 
 	/* Handle pure domain searches */

include/linux/irqdomain.h

@@ -212,6 +212,9 @@ enum {
 	/* Address and data pair is mutable when irq_set_affinity() */
 	IRQ_DOMAIN_FLAG_MSI_IMMUTABLE	= (1 << 11),
 
+	/* IRQ domain requires parent fwnode matching */
+	IRQ_DOMAIN_FLAG_FWNODE_PARENT	= (1 << 12),
+
 	/*
 	 * Flags starting from IRQ_DOMAIN_FLAG_NONCORE are reserved
 	 * for implementation specific purposes and ignored by the