PCI: Restrict device disabled status check to DT

Commit 6fffbc7a ("PCI: Honor firmware's device disabled status")
checked the firmware device status for both DT and ACPI devices. That
caused a regression in some ACPI systems. The exact reason isn't clear.
It's possibly a firmware bug. For now, at least, refactor the check to
be for DT based systems only.

Note that the original implementation leaked a refcount which is now
correctly handled.

[bhelgaas: Per ACPI r6.5, sec 6.3.7, for devices on an enumerable bus, _STA
must return with bit[0] ("device is present") set]

Link: https://lore.kernel.org/all/m2fs9lgndw.fsf@gmail.com/
Fixes: 6fffbc7a ("PCI: Honor firmware's device disabled status")
Link: https://lore.kernel.org/r/20230419193513.708818-1-robh@kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217317Reported-by: Donald Hunter <donald.hunter@gmail.com>
Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Tested-by: Donald Hunter <donald.hunter@gmail.com>
Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Binbin Zhou <zhoubinbin@loongson.cn>
Cc: Liu Peibao <liupeibao@loongson.cn>
Cc: Huacai Chen <chenhuacai@loongson.cn>

drivers/pci/of.c

@@ -16,14 +16,32 @@
 #include "pci.h"
 
 #ifdef CONFIG_PCI
-void pci_set_of_node(struct pci_dev *dev)
+/**
+ * pci_set_of_node - Find and set device's DT device_node
+ * @dev: the PCI device structure to fill
+ *
+ * Returns 0 on success with of_node set or when no device is described in the
+ * DT. Returns -ENODEV if the device is present, but disabled in the DT.
+ */
+int pci_set_of_node(struct pci_dev *dev)
 {
+	struct device_node *node;
+
 	if (!dev->bus->dev.of_node)
-		return;
-	dev->dev.of_node = of_pci_find_child_device(dev->bus->dev.of_node,
-						    dev->devfn);
-	if (dev->dev.of_node)
-		dev->dev.fwnode = &dev->dev.of_node->fwnode;
+		return 0;
+
+	node = of_pci_find_child_device(dev->bus->dev.of_node, dev->devfn);
+	if (!node)
+		return 0;
+
+	if (!of_device_is_available(node)) {
+		of_node_put(node);
+		return -ENODEV;
+	}
+
+	dev->dev.of_node = node;
+	dev->dev.fwnode = &node->fwnode;
+	return 0;
 }
 
 void pci_release_of_node(struct pci_dev *dev)

drivers/pci/pci.h

@@ -624,7 +624,7 @@ int of_pci_get_max_link_speed(struct device_node *node);
 u32 of_pci_get_slot_power_limit(struct device_node *node,
 				u8 *slot_power_limit_value,
 				u8 *slot_power_limit_scale);
-void pci_set_of_node(struct pci_dev *dev);
+int pci_set_of_node(struct pci_dev *dev);
 void pci_release_of_node(struct pci_dev *dev);
 void pci_set_bus_of_node(struct pci_bus *bus);
 void pci_release_bus_of_node(struct pci_bus *bus);
@@ -662,7 +662,7 @@ of_pci_get_slot_power_limit(struct device_node *node,
 	return 0;
 }
 
-static inline void pci_set_of_node(struct pci_dev *dev) { }
+static inline int pci_set_of_node(struct pci_dev *dev) { return 0; }
 static inline void pci_release_of_node(struct pci_dev *dev) { }
 static inline void pci_set_bus_of_node(struct pci_bus *bus) { }
 static inline void pci_release_bus_of_node(struct pci_bus *bus) { }

drivers/pci/probe.c

@@ -1826,7 +1826,7 @@ int pci_setup_device(struct pci_dev *dev)
 	u32 class;
 	u16 cmd;
 	u8 hdr_type;
-	int pos = 0;
+	int err, pos = 0;
 	struct pci_bus_region region;
 	struct resource *res;
 
@@ -1840,10 +1840,10 @@ int pci_setup_device(struct pci_dev *dev)
 	dev->error_state = pci_channel_io_normal;
 	set_pcie_port_type(dev);
 
-	pci_set_of_node(dev);
+	err = pci_set_of_node(dev);
+	if (err)
+		return err;
 	pci_set_acpi_fwnode(dev);
-	if (dev->dev.fwnode && !fwnode_device_is_available(dev->dev.fwnode))
-		return -ENODEV;
 
 	pci_dev_assign_slot(dev);