[PATCH v2 17/19] PCI: of_property: Add interrupt-controller property in PCI device nodes

Herve Codina
2024-05-27T16:15:29Z

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>
---
drivers/pci/of_property.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/drivers/pci/of_property.c b/drivers/pci/of_property.c
index 03539e505372..5a0b98e69795 100644
--- 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);
--
2.45.0