PCI: Unify pcie_find_root_port() and pci_find_pcie_root_port()

Previously we used pcie_find_root_port() to find a Root Port from a PCIe
device and pci_find_pcie_root_port() to find a Root Port from a
Conventional PCI device.

Unify the two functions and use pcie_find_root_port() to find a Root Port
from either a Conventional PCI device or a PCIe device.  Then there is no
need to distinguish the type of the device.

Link: https://lore.kernel.org/r/1589019568-5216-1-git-send-email-yangyicong@hisilicon.com
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com> # thunderbolt

drivers/pci/pci-acpi.c

@@ -948,7 +948,7 @@ static bool acpi_pci_bridge_d3(struct pci_dev *dev)
 	 * Look for a special _DSD property for the root port and if it
 	 * is set we know the hierarchy behind it supports D3 just fine.
 	 */
-	root = pci_find_pcie_root_port(dev);
+	root = pcie_find_root_port(dev);
 	if (!root)
 		return false;
 

drivers/pci/pci.c

@@ -751,30 +751,6 @@ struct resource *pci_find_resource(struct pci_dev *dev, struct resource *res)
 }
 EXPORT_SYMBOL(pci_find_resource);
 
-/**
- * pci_find_pcie_root_port - return PCIe Root Port
- * @dev: PCI device to query
- *
- * Traverse up the parent chain and return the PCIe Root Port PCI Device
- * for a given PCI Device.
- */
-struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev)
-{
-	struct pci_dev *bridge, *highest_pcie_bridge = dev;
-
-	bridge = pci_upstream_bridge(dev);
-	while (bridge && pci_is_pcie(bridge)) {
-		highest_pcie_bridge = bridge;
-		bridge = pci_upstream_bridge(bridge);
-	}
-
-	if (pci_pcie_type(highest_pcie_bridge) != PCI_EXP_TYPE_ROOT_PORT)
-		return NULL;
-
-	return highest_pcie_bridge;
-}
-EXPORT_SYMBOL(pci_find_pcie_root_port);
-
 /**
  * pci_wait_for_pending - wait for @mask bit(s) to clear in status word @pos
  * @dev: the PCI device to operate on

drivers/pci/probe.c

@@ -2056,7 +2056,7 @@ static void pci_configure_relaxed_ordering(struct pci_dev *dev)
 	 * For now, we only deal with Relaxed Ordering issues with Root
 	 * Ports. Peer-to-Peer DMA is another can of worms.
 	 */
-	root = pci_find_pcie_root_port(dev);
+	root = pcie_find_root_port(dev);
 	if (!root)
 		return;
 

drivers/pci/quirks.c

@@ -4319,7 +4319,7 @@ DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_AMD, 0x1a02, PCI_CLASS_NOT_DEFINED,
  */
 static void quirk_disable_root_port_attributes(struct pci_dev *pdev)
 {
-	struct pci_dev *root_port = pci_find_pcie_root_port(pdev);
+	struct pci_dev *root_port = pcie_find_root_port(pdev);
 
 	if (!root_port) {
 		pci_warn(pdev, "PCIe Completion erratum may cause device errors\n");

drivers/thunderbolt/switch.c

@@ -263,7 +263,7 @@ static void nvm_authenticate_start_dma_port(struct tb_switch *sw)
 	 * itself. To be on the safe side keep the root port in D0 during
 	 * the whole upgrade process.
 	 */
-	root_port = pci_find_pcie_root_port(sw->tb->nhi->pdev);
+	root_port = pcie_find_root_port(sw->tb->nhi->pdev);
 	if (root_port)
 		pm_runtime_get_noresume(&root_port->dev);
 }
@@ -272,7 +272,7 @@ static void nvm_authenticate_complete_dma_port(struct tb_switch *sw)
 {
 	struct pci_dev *root_port;
 
-	root_port = pci_find_pcie_root_port(sw->tb->nhi->pdev);
+	root_port = pcie_find_root_port(sw->tb->nhi->pdev);
 	if (root_port)
 		pm_runtime_put(&root_port->dev);
 }

include/linux/pci.h

@@ -1025,7 +1025,6 @@ void pci_bus_add_device(struct pci_dev *dev);
 void pci_read_bridge_bases(struct pci_bus *child);
 struct resource *pci_find_parent_resource(const struct pci_dev *dev,
 					  struct resource *res);
-struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev);
 u8 pci_swizzle_interrupt_pin(const struct pci_dev *dev, u8 pin);
 int pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge);
 u8 pci_common_swizzle(struct pci_dev *dev, u8 *pinp);
@@ -2143,17 +2142,23 @@ static inline int pci_pcie_type(const struct pci_dev *dev)
 	return (pcie_caps_reg(dev) & PCI_EXP_FLAGS_TYPE) >> 4;
 }
 
+/**
+ * pcie_find_root_port - Get the PCIe root port device
+ * @dev: PCI device
+ *
+ * Traverse up the parent chain and return the PCIe Root Port PCI Device
+ * for a given PCI/PCIe Device.
+ */
 static inline struct pci_dev *pcie_find_root_port(struct pci_dev *dev)
 {
-	while (1) {
+	struct pci_dev *bridge = pci_upstream_bridge(dev);
-		if (!pci_is_pcie(dev))
+
-			break;
+	while (bridge) {
-		if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
+		if (pci_pcie_type(bridge) == PCI_EXP_TYPE_ROOT_PORT)
-			return dev;
+			return bridge;
-		if (!dev->bus->self)
+		bridge = pci_upstream_bridge(bridge);
-			break;
-		dev = dev->bus->self;
 	}
+
 	return NULL;
 }