Merge branch 'pci/enumeration'

- Move the PRESERVE_BOOT_CONFIG ACPI _DSM evaluation from drivers/acpi to
  drivers/pci so we can unify with similar DT functionality (Vidya Sagar)

- Add of_pci_preserve_config() to check for a DT "linux,pci-probe-only"
  property on a per-host bridge basis in addition to a global basis (Vidya
  Sagar)

- Unify ACPI PRESERVE_BOOT_CONFIG _DSM and DT "linux,pci-probe-only" in a
  generic pci_preserve_config() path (Vidya Sagar)

* pci/enumeration:
  PCI: Use preserve_config in place of pci_flags
  PCI: Unify ACPI and DT 'preserve config' support
  PCI: of: Add of_pci_preserve_config() for per-host bridge support
  PCI: Move PRESERVE_BOOT_CONFIG _DSM evaluation to pci_register_host_bridge()

5 files changed, 100 insertions, 25 deletions

diff --git a/drivers/pci/controller/pci-host-common.c b/drivers/pci/controller/pci-host-common.c
index 45b71806182d..c96b2de163b5 100644
--- a/drivers/pci/controller/pci-host-common.c
+++ b/drivers/pci/controller/pci-host-common.c
@@ -73,10 +73,6 @@ int pci_host_common_probe(struct platform_device *pdev)
 	if (IS_ERR(cfg))
 		return PTR_ERR(cfg);
 
-	/* Do not reassign resources if probe only */
-	if (!pci_has_flag(PCI_PROBE_ONLY))
-		pci_add_flags(PCI_REASSIGN_ALL_BUS);
-
 	bridge->sysdata = cfg;
 	bridge->ops = (struct pci_ops *)&ops->pci_ops;
 	bridge->msi_domain = true;
diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index 51e3dd0ea5ab..48ba95e4ab05 100644
--- a/drivers/pci/of.c
+++ b/drivers/pci/of.c
@@ -234,27 +234,61 @@ int of_get_pci_domain_nr(struct device_node *node)
 EXPORT_SYMBOL_GPL(of_get_pci_domain_nr);
 
 /**
- * of_pci_check_probe_only - Setup probe only mode if linux,pci-probe-only
- *                           is present and valid
+ * of_pci_preserve_config - Return true if the boot configuration needs to
+ *                          be preserved
+ * @node: Device tree node.
+ *
+ * Look for "linux,pci-probe-only" property for a given PCI controller's
+ * node and return true if found. Also look in the chosen node if the
+ * property is not found in the given controller's node.  Having this
+ * property ensures that the kernel doesn't reconfigure the BARs and bridge
+ * windows that are already done by the platform firmware.
+ *
+ * Return: true if the property exists; false otherwise.
  */
-void of_pci_check_probe_only(void)
+bool of_pci_preserve_config(struct device_node *node)
 {
-	u32 val;
+	u32 val = 0;
 	int ret;
 
-	ret = of_property_read_u32(of_chosen, "linux,pci-probe-only", &val);
+	if (!node) {
+		pr_warn("device node is NULL, trying with of_chosen\n");
+		node = of_chosen;
+	}
+
+retry:
+	ret = of_property_read_u32(node, "linux,pci-probe-only", &val);
 	if (ret) {
-		if (ret == -ENODATA || ret == -EOVERFLOW)
-			pr_warn("linux,pci-probe-only without valid value, ignoring\n");
-		return;
+		if (ret == -ENODATA || ret == -EOVERFLOW) {
+			pr_warn("Incorrect value for linux,pci-probe-only in %pOF, ignoring\n",
+				node);
+			return false;
+		}
+		if (ret == -EINVAL) {
+			if (node == of_chosen)
+				return false;
+
+			node = of_chosen;
+			goto retry;
+		}
 	}
 
 	if (val)
+		return true;
+	else
+		return false;
+}
+
+/**
+ * of_pci_check_probe_only - Setup probe only mode if linux,pci-probe-only
+ *                           is present and valid
+ */
+void of_pci_check_probe_only(void)
+{
+	if (of_pci_preserve_config(of_chosen))
 		pci_add_flags(PCI_PROBE_ONLY);
 	else
 		pci_clear_flags(PCI_PROBE_ONLY);
-
-	pr_info("PROBE_ONLY %s\n", val ? "enabled" : "disabled");
 }
 EXPORT_SYMBOL_GPL(of_pci_check_probe_only);
 
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 004575091596..9cc447da9475 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -119,6 +119,28 @@ phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle)
 	return (phys_addr_t)mcfg_addr;
 }
 
+bool pci_acpi_preserve_config(struct pci_host_bridge *host_bridge)
+{
+	if (ACPI_HANDLE(&host_bridge->dev)) {
+		union acpi_object *obj;
+
+		/*
+		 * Evaluate the "PCI Boot Configuration" _DSM Function.  If it
+		 * exists and returns 0, we must preserve any PCI resource
+		 * assignments made by firmware for this host bridge.
+		 */
+		obj = acpi_evaluate_dsm_typed(ACPI_HANDLE(&host_bridge->dev),
+					      &pci_acpi_dsm_guid,
+					      1, DSM_PCI_PRESERVE_BOOT_CONFIG,
+					      NULL, ACPI_TYPE_INTEGER);
+		if (obj && obj->integer.value == 0)
+			return true;
+		ACPI_FREE(obj);
+	}
+
+	return false;
+}
+
 /* _HPX PCI Setting Record (Type 0); same as _HPP */
 struct hpx_type0 {
 	u32 revision;		/* Not present in _HPP */
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index e6d299b93c21..f04c81101da9 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -648,6 +648,7 @@ 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);
+bool of_pci_preserve_config(struct device_node *node);
 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);
@@ -686,6 +687,11 @@ of_pci_get_slot_power_limit(struct device_node *node,
 	return 0;
 }
 
+static inline bool of_pci_preserve_config(struct device_node *node)
+{
+	return false;
+}
+
 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) { }
@@ -732,6 +738,7 @@ static inline void pci_restore_aer_state(struct pci_dev *dev) { }
 #endif
 
 #ifdef CONFIG_ACPI
+bool pci_acpi_preserve_config(struct pci_host_bridge *bridge);
 int pci_acpi_program_hp_params(struct pci_dev *dev);
 extern const struct attribute_group pci_dev_acpi_attr_group;
 void pci_set_acpi_fwnode(struct pci_dev *dev);
@@ -745,6 +752,10 @@ int acpi_pci_wakeup(struct pci_dev *dev, bool enable);
 bool acpi_pci_need_resume(struct pci_dev *dev);
 pci_power_t acpi_pci_choose_state(struct pci_dev *pdev);
 #else
+static inline bool pci_acpi_preserve_config(struct pci_host_bridge *bridge)
+{
+	return false;
+}
 static inline int pci_dev_acpi_reset(struct pci_dev *dev, bool probe)
 {
 	return -ENOTTY;
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 8e696e547565..20475ca30505 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -889,6 +889,17 @@ static void pci_set_bus_msi_domain(struct pci_bus *bus)
 	dev_set_msi_domain(&bus->dev, d);
 }
 
+static bool pci_preserve_config(struct pci_host_bridge *host_bridge)
+{
+	if (pci_acpi_preserve_config(host_bridge))
+		return true;
+
+	if (host_bridge->dev.parent && host_bridge->dev.parent->of_node)
+		return of_pci_preserve_config(host_bridge->dev.parent->of_node);
+
+	return false;
+}
+
 static int pci_register_host_bridge(struct pci_host_bridge *bridge)
 {
 	struct device *parent = bridge->dev.parent;
@@ -983,6 +994,9 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
 	if (nr_node_ids > 1 && pcibus_to_node(bus) == NUMA_NO_NODE)
 		dev_warn(&bus->dev, "Unknown NUMA node; performance will be reduced\n");
 
+	/* Check if the boot configuration by FW needs to be preserved */
+	bridge->preserve_config = pci_preserve_config(bridge);
+
 	/* Coalesce contiguous windows */
 	resource_list_for_each_entry_safe(window, n, &resources) {
 		if (list_is_last(&window->node, &resources))
@@ -3080,20 +3094,18 @@ int pci_host_probe(struct pci_host_bridge *bridge)
 
 	bus = bridge->bus;
 
+	/* If we must preserve the resource configuration, claim now */
+	if (bridge->preserve_config)
+		pci_bus_claim_resources(bus);
+
 	/*
-	 * We insert PCI resources into the iomem_resource and
-	 * ioport_resource trees in either pci_bus_claim_resources()
-	 * or pci_bus_assign_resources().
+	 * Assign whatever was left unassigned. If we didn't claim above,
+	 * this will reassign everything.
 	 */
-	if (pci_has_flag(PCI_PROBE_ONLY)) {
-		pci_bus_claim_resources(bus);
-	} else {
-		pci_bus_size_bridges(bus);
-		pci_bus_assign_resources(bus);
+	pci_assign_unassigned_root_bus_resources(bus);
 
-		list_for_each_entry(child, &bus->children, node)
-			pcie_bus_configure_settings(child);
-	}
+	list_for_each_entry(child, &bus->children, node)
+		pcie_bus_configure_settings(child);
 
 	pci_bus_add_devices(bus);
 	return 0;