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.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: Yijing Wang <wangyijing@huawei.com>
Cc: Ma Jun <majun258@huawei.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Duc Dang <dhdang@apm.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1438091186-10244-5-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

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_add_device
+	 * 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));