PCI/MSI: Add support for OF-provided msi_domain

In order to populate the PCI host bridge msi_domain, use the
"msi-parent" attribute to lookup a corresponding irq domain.
If found, this is our MSI domain.

This gets plugged into the core PCI code.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
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: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1438091186-10244-6-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 29 insertions, 1 deletions

diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index f092993..85844d8 100644
--- a/drivers/pci/of.c
+++ b/drivers/pci/of.c
@@ -9,6 +9,7 @@
  * 2 of the License, or (at your option) any later version.
  */
 
+#include <linux/irqdomain.h>
 #include <linux/kernel.h>
 #include <linux/pci.h>
 #include <linux/of.h>
@@ -59,3 +60,27 @@ struct device_node * __weak pcibios_get_phb_of_node(struct pci_bus *bus)
 		return of_node_get(bus->bridge->parent->of_node);
 	return NULL;
 }
+
+struct irq_domain *pci_host_bridge_of_msi_domain(struct pci_bus *bus)
+{
+#ifdef CONFIG_IRQ_DOMAIN
+	struct device_node *np;
+	struct irq_domain *d;
+
+	if (!bus->dev.of_node)
+		return NULL;
+
+	/* Start looking for a phandle to an MSI controller. */
+	np = of_parse_phandle(bus->dev.of_node, "msi-parent", 0);
+	if (!np)
+		return NULL;
+
+	d = irq_find_matching_host(np, DOMAIN_BUS_PCI_MSI);
+	if (d)
+		return d;
+
+	return irq_find_host(np);
+#else
+	return NULL;
+#endif
+}
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index c03ecbf..a7afeac 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -663,12 +663,15 @@ static void pci_set_bus_speed(struct pci_bus *bus)
 
 static struct irq_domain *pci_host_bridge_msi_domain(struct pci_bus *bus)
 {
+	struct irq_domain *d;
+
 	/*
 	 * Any firmware interface that can resolve the msi_domain
 	 * should be called from here.
 	 */
+	d = pci_host_bridge_of_msi_domain(bus);
 
-	return NULL;
+	return d;
 }
 
 static void pci_set_bus_msi_domain(struct pci_bus *bus)