[irqchip: irq/irqchip-next] PCI/MSI: Add pci_msi_map_rid_ctlr_node() helper function

["irqchip-bot for Lorenzo Pieralisi" <tip-bot2@linutronix.de>]

The following commit has been merged into the irq/irqchip-next branch of irqchip:

Commit-ID:     cd0ec59affb1f31347170bbafadb9c5cc716bca9
Gitweb:        https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms/cd0ec59affb1f31347170bbafadb9c5cc716bca9
Author:        Lorenzo Pieralisi <lpieralisi@kernel.org>
AuthorDate:    Thu, 03 Jul 2025 12:25:15 +02:00
Committer:     Marc Zyngier <maz@kernel.org>
CommitterDate: Tue, 08 Jul 2025 18:35:52 +01:00

PCI/MSI: Add pci_msi_map_rid_ctlr_node() helper function

IRQchip drivers need a PCI/MSI function to map a RID to a MSI
controller deviceID namespace and at the same time retrieve the
struct device_node pointer of the MSI controller the RID is mapped
to.

Add pci_msi_map_rid_ctlr_node() to achieve this purpose.

Cc  Bjorn Helgaas <bhelgaas@google.com>

Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250703-gicv5-host-v7-25-12e71f1b3528@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 drivers/pci/msi/irqdomain.c | 20 ++++++++++++++++++++
 include/linux/msi.h         |  1 +
 2 files changed, 21 insertions(+)

diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
index c051527..8a6e80d 100644
--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -428,6 +428,26 @@ u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev)
 }
 
 /**
+ * pci_msi_map_rid_ctlr_node - Get the MSI controller node and MSI requester id (RID)
+ * @pdev:	The PCI device
+ * @node:	Pointer to store the MSI controller device node
+ *
+ * Use the firmware data to find the MSI controller node for @pdev.
+ * If found map the RID and initialize @node with it. @node value must
+ * be set to NULL on entry.
+ *
+ * Returns: The RID.
+ */
+u32 pci_msi_map_rid_ctlr_node(struct pci_dev *pdev, struct device_node **node)
+{
+	u32 rid = pci_dev_id(pdev);
+
+	pci_for_each_dma_alias(pdev, get_msi_id_cb, &rid);
+
+	return of_msi_xlate(&pdev->dev, node, rid);
+}
+
+/**
  * pci_msi_get_device_domain - Get the MSI domain for a given PCI device
  * @pdev:	The PCI device
  *
diff --git a/include/linux/msi.h b/include/linux/msi.h
index 6863540..a418e26 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -705,6 +705,7 @@ struct irq_domain *pci_msi_create_irq_domain(struct fwnode_handle *fwnode,
 					     struct msi_domain_info *info,
 					     struct irq_domain *parent);
 u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev);
+u32 pci_msi_map_rid_ctlr_node(struct pci_dev *pdev, struct device_node **node);
 struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev);
 #else /* CONFIG_PCI_MSI */
 static inline struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev)