genirq/msi: Optionally use dev->fwnode for device domain

To support wire to MSI domains via the MSI infrastructure it is required to
use the firmware node of the device which implements this for creating the
MSI domain. Otherwise the existing firmware match mechanisms to find the
correct irqdomain for a wired interrupt which is connected to a wire to MSI
bridge would fail.

This cannot be used for the general case because not all devices provide
firmware nodes and all regular per device MSI domains are directly
associated to the device and have not be searched for.
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/20240127161753.114685-11-apatel@ventanamicro.com

include/linux/msi.h

@@ -552,6 +552,8 @@ enum {
 	MSI_FLAG_ALLOC_SIMPLE_MSI_DESCS	= (1 << 5),
 	/* Free MSI descriptors */
 	MSI_FLAG_FREE_MSI_DESCS		= (1 << 6),
+	/* Use dev->fwnode for MSI device domain creation */
+	MSI_FLAG_USE_DEV_FWNODE		= (1 << 7),
 
 	/* Mask for the generic functionality */
 	MSI_GENERIC_FLAGS_MASK		= GENMASK(15, 0),

kernel/irq/msi.c

@@ -960,9 +960,9 @@ bool msi_create_device_irq_domain(struct device *dev, unsigned int domid,
 				  void *chip_data)
 {
 	struct irq_domain *domain, *parent = dev->msi.domain;
-	const struct msi_parent_ops *pops;
+	struct fwnode_handle *fwnode, *fwnalloced = NULL;
 	struct msi_domain_template *bundle;
-	struct fwnode_handle *fwnode;
+	const struct msi_parent_ops *pops;
 
 	if (!irq_domain_is_msi_parent(parent))
 		return false;
@@ -985,7 +985,19 @@ bool msi_create_device_irq_domain(struct device *dev, unsigned int domid,
 		 pops->prefix ? : "", bundle->chip.name, dev_name(dev));
 	bundle->chip.name = bundle->name;
 
-	fwnode = irq_domain_alloc_named_fwnode(bundle->name);
+	/*
+	 * Using the device firmware node is required for wire to MSI
+	 * device domains so that the existing firmware results in a domain
+	 * match.
+	 * All other device domains like PCI/MSI use the named firmware
+	 * node as they are not guaranteed to have a fwnode. They are never
+	 * looked up and always handled in the context of the device.
+	 */
+	if (bundle->info.flags & MSI_FLAG_USE_DEV_FWNODE)
+		fwnode = dev->fwnode;
+	else
+		fwnode = fwnalloced = irq_domain_alloc_named_fwnode(bundle->name);
+
 	if (!fwnode)
 		goto free_bundle;
 
@@ -1012,7 +1024,7 @@ bool msi_create_device_irq_domain(struct device *dev, unsigned int domid,
 fail:
 	msi_unlock_descs(dev);
 free_fwnode:
-	irq_domain_free_fwnode(fwnode);
+	irq_domain_free_fwnode(fwnalloced);
 free_bundle:
 	kfree(bundle);
 	return false;