PCI: of_property: Add interrupt-controller property in PCI device nodes

PCI devices and bridges DT nodes created during the PCI scan are created
with the interrupt-map property set to handle interrupts.

In order to set this interrupt-map property at a specific level, a
phandle to the parent interrupt controller is needed. On systems that
are not fully described by a device-tree, the parent interrupt
controller may be unavailable (i.e. not described by the device-tree).

As mentioned in the [1], avoiding the use of the interrupt-map property
and considering a PCI device as an interrupt controller itself avoid the
use of a parent interrupt phandle.

In that case, the PCI device itself as an interrupt controller is
responsible for routing the interrupts described in the device-tree
world (DT overlay) to the PCI interrupts.

Add the 'interrupt-controller' property in the PCI device DT node.

[1]: https://lore.kernel.org/lkml/CAL_Jsq+je7+9ATR=B6jXHjEJHjn24vQFs4Tvi9=vhDeK9n42Aw@mail.gmail.com/

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20240527161450.326615-18-herve.codina@bootlin.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

diff --git a/drivers/pci/of_property.c b/drivers/pci/of_property.c
index 03539e5053720f9e620077790a9f831f904e93b5..5a0b98e697954a0b05a9487b04a588afe6f65d96 100644 (file)
--- a/drivers/pci/of_property.c
+++ b/drivers/pci/of_property.c
@@ -183,6 +183,26 @@ static int of_pci_prop_interrupts(struct pci_dev *pdev,
        return of_changeset_add_prop_u32(ocs, np, "interrupts", (u32)pin);
 }
 
+static int of_pci_prop_intr_ctrl(struct pci_dev *pdev, struct of_changeset *ocs,
+                                struct device_node *np)
+{
+       int ret;
+       u8 pin;
+
+       ret = pci_read_config_byte(pdev, PCI_INTERRUPT_PIN, &pin);
+       if (ret != 0)
+               return ret;
+
+       if (!pin)
+               return 0;
+
+       ret = of_changeset_add_prop_u32(ocs, np, "#interrupt-cells", 1);
+       if (ret)
+               return ret;
+
+       return of_changeset_add_prop_bool(ocs, np, "interrupt-controller");
+}
+
 static int of_pci_prop_intr_map(struct pci_dev *pdev, struct of_changeset *ocs,
                                struct device_node *np)
 {
@@ -336,6 +356,10 @@ int of_pci_add_properties(struct pci_dev *pdev, struct of_changeset *ocs,
                ret = of_pci_prop_intr_map(pdev, ocs, np);
                if (ret)
                        return ret;
+       } else {
+               ret = of_pci_prop_intr_ctrl(pdev, ocs, np);
+               if (ret)
+                       return ret;
        }
 
        ret = of_pci_prop_ranges(pdev, ocs, np);