PCI: host-generic: Move bridge allocation outside of pci_host_common_init()

Having the host bridge allocation inside pci_host_common_init() results
in a lot of complexity in the pcie-apple driver (the only direct user
of this function outside of core PCI code).

It forces the allocation of driver-specific tracking structures outside
of the bridge allocation, which in turn requires it to use inefficient
data structures to match the bridge and the private structure as needed.

Instead, let the bridge structure be passed to pci_host_common_init(),
allowing the driver to allocate it together with the private data,
as it is usually intended. The driver can then retrieve the bridge
via the owning device attached to the PCI config window structure.
This allows the pcie-apple driver to be significantly simplified.

Both core and driver code are changed in one go to avoid going via
a transitional interface.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Radu Rendec <rrendec@redhat.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Manivannan Sadhasivam <mani@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Krzysztof Wilczyński <kwilczynski@kernel.org>
Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
Link: https://lore.kernel.org/r/86jyzms036.wl-maz@kernel.org
Link: https://patch.msgid.link/20251125102726.865617-1-maz@kernel.org

Author: Marc Zyngier

drivers/pci/controller/pci-host-common.c

@@ -53,16 +53,12 @@ struct pci_config_window *pci_host_common_ecam_create(struct device *dev,
 EXPORT_SYMBOL_GPL(pci_host_common_ecam_create);
 
 int pci_host_common_init(struct platform_device *pdev,
+			 struct pci_host_bridge *bridge,
 			 const struct pci_ecam_ops *ops)
 {
 	struct device *dev = &pdev->dev;
-	struct pci_host_bridge *bridge;
 	struct pci_config_window *cfg;
 
-	bridge = devm_pci_alloc_host_bridge(dev, 0);
-	if (!bridge)
-		return -ENOMEM;
-
 	of_pci_check_probe_only();
 
 	platform_set_drvdata(pdev, bridge);
@@ -85,12 +81,17 @@ EXPORT_SYMBOL_GPL(pci_host_common_init);
 int pci_host_common_probe(struct platform_device *pdev)
 {
 	const struct pci_ecam_ops *ops;
+	struct pci_host_bridge *bridge;
 
 	ops = of_device_get_match_data(&pdev->dev);
 	if (!ops)
 		return -ENODEV;
 
-	return pci_host_common_init(pdev, ops);
+	bridge = devm_pci_alloc_host_bridge(&pdev->dev, 0);
+	if (!bridge)
+		return -ENOMEM;
+
+	return pci_host_common_init(pdev, bridge, ops);
 }
 EXPORT_SYMBOL_GPL(pci_host_common_probe);
 

drivers/pci/controller/pci-host-common.h

@@ -14,6 +14,7 @@ struct pci_ecam_ops;
 
 int pci_host_common_probe(struct platform_device *pdev);
 int pci_host_common_init(struct platform_device *pdev,
+			 struct pci_host_bridge *bridge,
 			 const struct pci_ecam_ops *ops);
 void pci_host_common_remove(struct platform_device *pdev);
 

drivers/pci/controller/pcie-apple.c

@@ -187,7 +187,6 @@ struct apple_pcie {
 	const struct hw_info	*hw;
 	unsigned long		*bitmap;
 	struct list_head	ports;
-	struct list_head	entry;
 	struct completion	event;
 	struct irq_fwspec	fwspec;
 	u32			nvecs;
@@ -206,9 +205,6 @@ struct apple_pcie_port {
 	int			idx;
 };
 
-static LIST_HEAD(pcie_list);
-static DEFINE_MUTEX(pcie_list_lock);
-
 static void rmw_set(u32 set, void __iomem *addr)
 {
 	writel_relaxed(readl_relaxed(addr) | set, addr);
@@ -724,32 +720,9 @@ static int apple_msi_init(struct apple_pcie *pcie)
 	return 0;
 }
 
-static void apple_pcie_register(struct apple_pcie *pcie)
-{
-	guard(mutex)(&pcie_list_lock);
-
-	list_add_tail(&pcie->entry, &pcie_list);
-}
-
-static void apple_pcie_unregister(struct apple_pcie *pcie)
-{
-	guard(mutex)(&pcie_list_lock);
-
-	list_del(&pcie->entry);
-}
-
 static struct apple_pcie *apple_pcie_lookup(struct device *dev)
 {
-	struct apple_pcie *pcie;
-
-	guard(mutex)(&pcie_list_lock);
-
-	list_for_each_entry(pcie, &pcie_list, entry) {
-		if (pcie->dev == dev)
-			return pcie;
-	}
-
-	return NULL;
+	return pci_host_bridge_priv(dev_get_drvdata(dev));
 }
 
 static struct apple_pcie_port *apple_pcie_get_port(struct pci_dev *pdev)
@@ -875,13 +848,15 @@ static const struct pci_ecam_ops apple_pcie_cfg_ecam_ops = {
 static int apple_pcie_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	struct pci_host_bridge *bridge;
 	struct apple_pcie *pcie;
 	int ret;
 
-	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
-	if (!pcie)
+	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*pcie));
+	if (!bridge)
 		return -ENOMEM;
 
+	pcie = pci_host_bridge_priv(bridge);
 	pcie->dev = dev;
 	pcie->hw = of_device_get_match_data(dev);
 	if (!pcie->hw)
@@ -897,13 +872,7 @@ static int apple_pcie_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	apple_pcie_register(pcie);
-
-	ret = pci_host_common_init(pdev, &apple_pcie_cfg_ecam_ops);
-	if (ret)
-		apple_pcie_unregister(pcie);
-
-	return ret;
+	return pci_host_common_init(pdev, bridge, &apple_pcie_cfg_ecam_ops);
 }
 
 static const struct of_device_id apple_pcie_of_match[] = {