[PATCH v5 04/19] PCI/MSI: Add hooks to populate the msi_domain field

In order to be able to populate the device msi_domain field,
add the necessary hooks to propagate the host bridge msi_domain
across secondary busses to devices.

So far, nobody populates the initial msi_domain.

Signed-off-by: Marc Zyngier <redacted>
---
  drivers/pci/probe.c | 42 ++++++++++++++++++++++++++++++++++++++++++
  1 file changed, 42 insertions(+)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index cefd636..2fd4f8e 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c

@@ -661,6 +661,32 @@ static void pci_set_bus_speed(struct pci_bus *bus)
  	}
  }

+static struct irq_domain *pci_host_bridge_msi_domain(struct pci_bus *bus)
+{
+	/*
+	 * Any firmware interface that can resolve the msi_domain
+	 * should be called from here.
+	 */
+
+	return NULL;
+}
+
+static void pci_set_bus_msi_domain(struct pci_bus *bus)
+{
+	struct irq_domain *d;
+
+	/*
+	 * Either bus is the root, and we must obtain it from the
+	 * firmware, or we inherit it from the bridge device.
+	 */
+	if (pci_is_root_bus(bus))
+		d = pci_host_bridge_msi_domain(bus);
+	else
+		d = dev_get_msi_domain(&bus->self->dev);
+
+	dev_set_msi_domain(&bus->dev, d);
+}
+
  static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
  					   struct pci_dev *bridge, int busnr)
  {

@@ -714,6 +740,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
  	bridge->subordinate = child;

  add_dev:
+	pci_set_bus_msi_domain(child);
  	ret = device_register(&child->dev);
  	WARN_ON(ret < 0);

@@ -1544,6 +1571,17 @@ static void pci_init_capabilities(struct pci_dev *dev)
  	pci_enable_acs(dev);
  }

+static void pci_set_msi_domain(struct pci_dev *dev)
+{
+	/*
+	 * If no domain has been set through the pcibios callback,
+	 * inherit the default from the bus device.
+	 */
+	if (!dev_get_msi_domain(&dev->dev))
+		dev_set_msi_domain(&dev->dev,
+				   dev_get_msi_domain(&dev->bus->dev));
+}
+
  void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
  {
  	int ret;

@@ -1585,6 +1623,9 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
  	ret = pcibios_add_device(dev);
  	WARN_ON(ret < 0);

+	/* Setup MSI irq domain */
+	pci_set_msi_domain(dev);
+
  	/* Notifier could use PCI capabilities */
  	dev->match_driver = false;
  	ret = device_add(&dev->dev);

@@ -1975,6 +2016,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
  	b->bridge = get_device(&bridge->dev);
  	device_enable_async_suspend(b->bridge);
  	pci_set_bus_of_node(b);
+	pci_set_bus_msi_domain(b);

  	if (!parent)
  		set_dev_node(b->bridge, pcibus_to_node(b));