Introduce generic helper functions to parse Root Port device tree nodes
and extract common properties like reset GPIOs. This allows multiple
PCI host controller drivers to share the same parsing logic.

Define struct pci_host_port to hold common Root Port properties
(currently only reset GPIO descriptor) and add
pci_host_common_parse_ports() to parse Root Port nodes from device tree.

Also add the 'ports' list to struct pci_host_bridge for better maintain
parsed Root Port information.

Signed-off-by: Sherry Sun <redacted>
---
 drivers/pci/controller/pci-host-common.c | 78 ++++++++++++++++++++++++
 drivers/pci/controller/pci-host-common.h | 15 +++++
 drivers/pci/probe.c                      |  1 +
 include/linux/pci.h                      |  1 +
 4 files changed, 95 insertions(+)

diff --git a/drivers/pci/controller/pci-host-common.c b/drivers/pci/controller/pci-host-common.c
index d6258c1cffe5..2f012cf80463 100644
--- a/drivers/pci/controller/pci-host-common.c
+++ b/drivers/pci/controller/pci-host-common.c

@@ -9,6 +9,7 @@
 
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/gpio/consumer.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_pci.h>

@@ -17,6 +18,83 @@
 
 #include "pci-host-common.h"
 
+/**
+ * pci_host_common_delete_ports - Cleanup function for port list
+ * @data: Pointer to the port list head
+ */
+static void pci_host_common_delete_ports(void *data)
+{
+	struct list_head *ports = data;
+	struct pci_host_port *port, *tmp;
+
+	list_for_each_entry_safe(port, tmp, ports, list)
+		list_del(&port->list);
+}
+
+/**
+ * pci_host_common_parse_port - Parse a single Root Port node
+ * @dev: Device pointer
+ * @bridge: PCI host bridge
+ * @node: Device tree node of the Root Port
+ *
+ * Returns: 0 on success, negative error code on failure
+ */
+static int pci_host_common_parse_port(struct device *dev,
+				      struct pci_host_bridge *bridge,
+				      struct device_node *node)
+{
+	struct pci_host_port *port;
+	struct gpio_desc *reset;
+
+	reset = devm_fwnode_gpiod_get(dev, of_fwnode_handle(node),
+				      "reset", GPIOD_ASIS, "PERST#");
+	if (IS_ERR(reset))
+		return PTR_ERR(reset);
+
+	port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
+	if (!port)
+		return -ENOMEM;
+
+	port->reset = reset;
+	INIT_LIST_HEAD(&port->list);
+	list_add_tail(&port->list, &bridge->ports);
+
+	return 0;
+}
+
+/**
+ * pci_host_common_parse_ports - Parse Root Port nodes from device tree
+ * @dev: Device pointer
+ * @bridge: PCI host bridge
+ *
+ * This function iterates through child nodes of the host bridge and parses
+ * Root Port properties (currently only reset GPIO).
+ *
+ * Returns: 0 on success, -ENOENT if no ports found, other negative error codes
+ * on failure
+ */
+int pci_host_common_parse_ports(struct device *dev, struct pci_host_bridge *bridge)
+{
+	int ret = -ENOENT;
+	int err;
+
+	for_each_available_child_of_node_scoped(dev->of_node, of_port) {
+		if (!of_node_is_type(of_port, "pci"))
+			continue;
+		ret = pci_host_common_parse_port(dev, bridge, of_port);
+		if (ret)
+			return ret;
+	}
+