[PATCH v2 2/6] PCI: Set PCI_BUS_FLAGS_MSI_REMAP if MSI controller enables IRQ remapping

[Yongji Xie]

On ARM HW the capability of IRQ remapping is abstracted on
MSI controller side. MSI_FLAG_IRQ_REMAPPING is used to advertise
this [1].

To have a universal flag to test this capability for different
archs on PCI side, we set PCI_BUS_FLAGS_MSI_REMAP for PCI buses
when MSI_FLAG_IRQ_REMAPPING is set.

[1] https://www.mail-archive.com/linux-kernel%40vger.kernel.org/msg1138820.html

Signed-off-by: Yongji Xie <xyjxie@xxxxxxxxxxxxxxxxxx>
---
 drivers/pci/msi.c   |   15 +++++++++++++++
 drivers/pci/probe.c |    3 +++
 include/linux/msi.h |    5 ++++-
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index a080f44..dbdb5c3 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -1134,6 +1134,21 @@ void *msi_desc_to_pci_sysdata(struct msi_desc *desc)
 }
 EXPORT_SYMBOL_GPL(msi_desc_to_pci_sysdata);
 
+int pci_bus_msi_isolated(struct pci_bus *bus, struct irq_domain *domain)
+{
+#ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
+	struct msi_domain_info *info;
+
+	if (!domain)
+		return 0;
+
+	info = msi_get_domain_info(domain);
+	if (info->flags & MSI_FLAG_IRQ_REMAPPING)
+		return 1;
+#endif
+	return 0;
+}
+
 #ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
 /**
  * pci_msi_domain_write_msg - Helper to write MSI message to PCI config space
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 8004f67..2b9e3ba 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -713,6 +713,9 @@ static void pci_set_bus_msi_domain(struct pci_bus *bus)
 	if (!d)
 		d = pci_host_bridge_msi_domain(b);
 
+	if (b == bus && pci_bus_msi_isolated(bus, d))
+		bus->bus_flags |= PCI_BUS_FLAGS_MSI_REMAP;
+
 	dev_set_msi_domain(&bus->dev, d);
 }
 
diff --git a/include/linux/msi.h b/include/linux/msi.h
index 08441b1..04cc749 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -15,6 +15,8 @@ extern int pci_msi_ignore_mask;
 struct irq_data;
 struct msi_desc;
 struct pci_dev;
+struct pci_bus;
+struct irq_domain;
 struct platform_msi_priv_data;
 void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
 void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);
@@ -164,6 +166,8 @@ void arch_restore_msi_irqs(struct pci_dev *dev);
 void default_teardown_msi_irqs(struct pci_dev *dev);
 void default_restore_msi_irqs(struct pci_dev *dev);
 
+int pci_bus_msi_isolated(struct pci_bus *bus, struct irq_domain *domain);
+
 struct msi_controller {
 	struct module *owner;
 	struct device *dev;
@@ -182,7 +186,6 @@ struct msi_controller {
 #include <linux/irqhandler.h>
 #include <asm/msi.h>
 
-struct irq_domain;
 struct irq_domain_ops;
 struct irq_chip;
 struct device_node;
-- 
1.7.9.5