PCI/MSI: Allow the MSI domain to be device-specific

So far, we've always considered that for a given PCI device, its
MSI controller was either set by the architecture-specific
pcibios hook, or simply inherited from the host bridge.

This doesn't cover things like firmware-defined topologies like
msi-map (DT) or IORT (ACPI), which can provide information about
which MSI controller to use on a per-device basis.

This patch adds the necessary hook into the MSI code to allow this
feature, and provides the msi-map functionnality as a first
implementation.

Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 5ab5c4f8dcb013f2e94927c5d41084f3308818d8..4cd6f3abcecf2d302561ee2646be0450e6e490cc 100644 (file)
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -1359,4 +1359,21 @@ u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev)
 
        return rid;
 }
+
+/**
+ * pci_msi_get_device_domain - Get the MSI domain for a given PCI device
+ * @pdev:      The PCI device
+ *
+ * Use the firmware data to find a device-specific MSI domain
+ * (i.e. not one that is ste as a default).
+ *
+ * Returns: The coresponding MSI domain or NULL if none has been found.
+ */
+struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev)
+{
+       u32 rid = 0;
+
+       pci_for_each_dma_alias(pdev, get_msi_id_cb, &rid);
+       return of_msi_map_get_device_domain(&pdev->dev, rid);
+}
 #endif /* CONFIG_PCI_MSI_IRQ_DOMAIN */

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 7c333f8c2327104f62fea69d35bf2601d64efb0f..f14a970b61fa59bf00b6e97474da3ec024ba315e 100644 (file)
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1639,6 +1639,14 @@ static struct irq_domain *pci_dev_msi_domain(struct pci_dev *dev)
        if (d)
                return d;
 
+       /*
+        * Let's see if we have a firmware interface able to provide
+        * the domain.
+        */
+       d = pci_msi_get_device_domain(dev);
+       if (d)
+               return d;
+
        return NULL;
 }
 

diff --git a/include/linux/msi.h b/include/linux/msi.h
index 87723751054dd8ea4e60e4cba1a403ccc7590d04..0b4460374020fd98e40248c990eb6110493a21be 100644 (file)
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -295,6 +295,12 @@ irq_hw_number_t pci_msi_domain_calc_hwirq(struct pci_dev *dev,
 int pci_msi_domain_check_cap(struct irq_domain *domain,
                             struct msi_domain_info *info, struct device *dev);
 u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev);
+struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev);
+#else
+static inline struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev)
+{
+       return NULL;
+}
 #endif /* CONFIG_PCI_MSI_IRQ_DOMAIN */
 
 #endif /* LINUX_MSI_H */