PCI: ACPI: Add helper to register the MSI domain directly.

Some architectures like X86, sets up the MSI domain but not registered
with IRQ framework. This causes pci_host_bridge_acpi_msi_domain() to not
find it. pci_msi_register_fwnode_provider() can not be used because
these domains seem to be created differently as in
native_create_pci_msi_domain(). Hence, add a new helper to register the
domain directly and check this first while searching for the MSI domain.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>

X86: msi.c: Register the MSI domain with IRQ framework

Register the default MSI irq domain so that
pci_host_bridge_acpi_msi_domain() is able to the MSI domain from PCI
host bridge.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>

arch/x86/kernel/apic/msi.c

@@ -278,6 +278,7 @@ struct irq_domain * __init native_create_pci_msi_domain(void)
 void __init x86_create_pci_msi_domain(void)
 {
 	x86_pci_msi_default_domain = x86_init.irqs.create_pci_msi_domain();
+	pci_msi_register_default_domain(x86_pci_msi_default_domain);
 }
 
 /* Keep around for hyperV */

drivers/pci/pci-acpi.c

@@ -1461,6 +1461,7 @@ void pci_acpi_cleanup(struct device *dev, struct acpi_device *adev)
 }
 
 static struct fwnode_handle *(*pci_msi_get_fwnode_cb)(struct device *dev);
+static struct irq_domain *pci_msi_default_domain;
 
 /**
  * pci_msi_register_fwnode_provider - Register callback to retrieve fwnode
@@ -1476,6 +1477,17 @@ pci_msi_register_fwnode_provider(struct fwnode_handle *(*fn)(struct device *))
 	pci_msi_get_fwnode_cb = fn;
 }
 
+/**
+ * pci_msi_register_default_domain - Register default MSI domain
+ *
+ * This should be called by irqchip driver, which is the parent of
+ * the MSI domain to provide callback interface to query fwnode.
+ */
+void pci_msi_register_default_domain(struct irq_domain *msidom)
+{
+	pci_msi_default_domain = msidom;
+}
+
 /**
  * pci_host_bridge_acpi_msi_domain - Retrieve MSI domain of a PCI host bridge
  * @bus:      The PCI host bridge bus.
@@ -1489,6 +1501,9 @@ struct irq_domain *pci_host_bridge_acpi_msi_domain(struct pci_bus *bus)
 {
 	struct fwnode_handle *fwnode;
 
+	if (pci_msi_default_domain)
+		return pci_msi_default_domain;
+
 	if (!pci_msi_get_fwnode_cb)
 		return NULL;
 

include/linux/pci.h

@@ -2614,6 +2614,7 @@ struct irq_domain *pci_host_bridge_acpi_msi_domain(struct pci_bus *bus);
 
 void
 pci_msi_register_fwnode_provider(struct fwnode_handle *(*fn)(struct device *));
+void pci_msi_register_default_domain(struct irq_domain *msidom);
 bool pci_pr3_present(struct pci_dev *pdev);
 #else
 static inline struct irq_domain *