linux-kernel - [PATCH 4/6] PCI: of: Add an API to get the BDF for the device node

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Message-Id: <20250819-pci-pwrctrl-perst-v1-4-4b74978d2007@oss.qualcomm.com>
Date: Tue, 19 Aug 2025 12:44:53 +0530
From: Manivannan Sadhasivam via B4 Relay <devnull+manivannan.sadhasivam.oss.qualcomm.com@...nel.org>
To: Manivannan Sadhasivam <mani@...nel.org>, 
 Lorenzo Pieralisi <lpieralisi@...nel.org>, 
 Krzysztof Wilczyński <kwilczynski@...nel.org>, 
 Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>, 
 Bartosz Golaszewski <brgl@...ev.pl>, Saravana Kannan <saravanak@...gle.com>
Cc: linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
 Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>, 
 Brian Norris <briannorris@...omium.org>, 
 Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
Subject: [PATCH 4/6] PCI: of: Add an API to get the BDF for the device node

From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>

Bus:Device:Function (BDF) numbers are used to uniquely identify a
device/function on a PCI bus. Hence, add an API to get the BDF from the
devicetree node of a device.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
---
 drivers/pci/of.c       | 21 +++++++++++++++++++++
 include/linux/of_pci.h |  6 ++++++
 2 files changed, 27 insertions(+)

diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index 3579265f119845637e163d9051437c89662762f8..5e584d25434291430145e510b1d49a371dce9165 100644
--- a/drivers/pci/of.c
+++ b/drivers/pci/of.c
@@ -183,6 +183,27 @@ int of_pci_get_devfn(struct device_node *np)
 }
 EXPORT_SYMBOL_GPL(of_pci_get_devfn);
 
+/**
+ * of_pci_get_bdf() - Get Bus:Device:Function (BDF) numbers for a device node
+ * @np: device node
+ *
+ * Parses a standard 5-cell PCI resource and returns an 16-bit value that
+ * corresponds to the BDF of the node. On error, a negative error code is
+ * returned.
+ */
+int of_pci_get_bdf(struct device_node *np)
+{
+	u32 reg[5];
+	int error;
+
+	error = of_property_read_u32_array(np, "reg", reg, ARRAY_SIZE(reg));
+	if (error)
+		return error;
+
+	return (reg[0] >> 8) & 0xffff;
+}
+EXPORT_SYMBOL_GPL(of_pci_get_bdf);
+
 /**
  * of_pci_parse_bus_range() - parse the bus-range property of a PCI device
  * @node: device node
diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
index 29658c0ee71ff10122760214d04ee2bab01709fd..b36ac10653c82f4efdbb57cea56d2ec9d581212f 100644
--- a/include/linux/of_pci.h
+++ b/include/linux/of_pci.h
@@ -12,6 +12,7 @@ struct device_node;
 struct device_node *of_pci_find_child_device(struct device_node *parent,
 					     unsigned int devfn);
 int of_pci_get_devfn(struct device_node *np);
+int of_pci_get_bdf(struct device_node *np);
 void of_pci_check_probe_only(void);
 #else
 static inline struct device_node *of_pci_find_child_device(struct device_node *parent,
@@ -25,6 +26,11 @@ static inline int of_pci_get_devfn(struct device_node *np)
 	return -EINVAL;
 }
 
+static inline int of_pci_get_bdf(struct device_node *np)
+{
+	return -EINVAL;
+}
+
 static inline void of_pci_check_probe_only(void) { }
 #endif
 

-- 
2.45.2