PCI: mediatek: Add loadable kernel module support

Implement remove() callback function for the Mediatek PCIe controller
driver to add loadable kernel module support.

Save the PCIe's GIC IRQ at probe so that it can be retrieved to
call dispose_irq() to tear down the IRQ upon module removal.

Signed-off-by: Honghui Zhang <honghui.zhang@mediatek.com>
[lorenzo.pieralisi@arm.com: updated commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Ryder Lee <ryder.lee@mediatek.com>

drivers/pci/controller/Kconfig

@@ -231,7 +231,7 @@ config PCIE_ROCKCHIP_EP
 	  available to support GEN2 with 4 slots.
 
 config PCIE_MEDIATEK
-	bool "MediaTek PCIe controller"
+	tristate "MediaTek PCIe controller"
 	depends on ARCH_MEDIATEK || COMPILE_TEST
 	depends on OF
 	depends on PCI_MSI_IRQ_DOMAIN

drivers/pci/controller/pcie-mediatek.c

@@ -15,6 +15,7 @@
 #include <linux/irqdomain.h>
 #include <linux/kernel.h>
 #include <linux/msi.h>
+#include <linux/module.h>
 #include <linux/of_address.h>
 #include <linux/of_pci.h>
 #include <linux/of_platform.h>
@@ -162,6 +163,7 @@ struct mtk_pcie_soc {
  * @phy: pointer to PHY control block
  * @lane: lane count
  * @slot: port slot
+ * @irq: GIC irq
  * @irq_domain: legacy INTx IRQ domain
  * @inner_domain: inner IRQ domain
  * @msi_domain: MSI IRQ domain
@@ -182,6 +184,7 @@ struct mtk_pcie_port {
 	struct phy *phy;
 	u32 lane;
 	u32 slot;
+	int irq;
 	struct irq_domain *irq_domain;
 	struct irq_domain *inner_domain;
 	struct irq_domain *msi_domain;
@@ -530,6 +533,27 @@ static void mtk_pcie_enable_msi(struct mtk_pcie_port *port)
 	writel(val, port->base + PCIE_INT_MASK);
 }
 
+static void mtk_pcie_irq_teardown(struct mtk_pcie *pcie)
+{
+	struct mtk_pcie_port *port, *tmp;
+
+	list_for_each_entry_safe(port, tmp, &pcie->ports, list) {
+		irq_set_chained_handler_and_data(port->irq, NULL, NULL);
+
+		if (port->irq_domain)
+			irq_domain_remove(port->irq_domain);
+
+		if (IS_ENABLED(CONFIG_PCI_MSI)) {
+			if (port->msi_domain)
+				irq_domain_remove(port->msi_domain);
+			if (port->inner_domain)
+				irq_domain_remove(port->inner_domain);
+		}
+
+		irq_dispose_mapping(port->irq);
+	}
+}
+
 static int mtk_pcie_intx_map(struct irq_domain *domain, unsigned int irq,
 			     irq_hw_number_t hwirq)
 {
@@ -620,16 +644,17 @@ static int mtk_pcie_setup_irq(struct mtk_pcie_port *port,
 	struct mtk_pcie *pcie = port->pcie;
 	struct device *dev = pcie->dev;
 	struct platform_device *pdev = to_platform_device(dev);
-	int err, irq;
+	int err;
 
 	err = mtk_pcie_init_irq_domain(port, node);
 	if (err) {
 		dev_err(dev, "failed to init PCIe IRQ domain\n");
 		return err;
 	}
 
-	irq = platform_get_irq(pdev, port->slot);
-	irq_set_chained_handler_and_data(irq, mtk_pcie_intr_handler, port);
+	port->irq = platform_get_irq(pdev, port->slot);
+	irq_set_chained_handler_and_data(port->irq,
+					 mtk_pcie_intr_handler, port);
 
 	return 0;
 }
@@ -1168,6 +1193,31 @@ static int mtk_pcie_probe(struct platform_device *pdev)
 	return err;
 }
 
+
+static void mtk_pcie_free_resources(struct mtk_pcie *pcie)
+{
+	struct pci_host_bridge *host = pci_host_bridge_from_priv(pcie);
+	struct list_head *windows = &host->windows;
+
+	pci_free_resource_list(windows);
+}
+
+static int mtk_pcie_remove(struct platform_device *pdev)
+{
+	struct mtk_pcie *pcie = platform_get_drvdata(pdev);
+	struct pci_host_bridge *host = pci_host_bridge_from_priv(pcie);
+
+	pci_stop_root_bus(host->bus);
+	pci_remove_root_bus(host->bus);
+	mtk_pcie_free_resources(pcie);
+
+	mtk_pcie_irq_teardown(pcie);
+
+	mtk_pcie_put_resources(pcie);
+
+	return 0;
+}
+
 static int __maybe_unused mtk_pcie_suspend_noirq(struct device *dev)
 {
 	struct mtk_pcie *pcie = dev_get_drvdata(dev);
@@ -1245,11 +1295,13 @@ static const struct of_device_id mtk_pcie_ids[] = {
 
 static struct platform_driver mtk_pcie_driver = {
 	.probe = mtk_pcie_probe,
+	.remove = mtk_pcie_remove,
 	.driver = {
 		.name = "mtk-pcie",
 		.of_match_table = mtk_pcie_ids,
 		.suppress_bind_attrs = true,
 		.pm = &mtk_pcie_pm_ops,
 	},
 };
-builtin_platform_driver(mtk_pcie_driver);
+module_platform_driver(mtk_pcie_driver);
+MODULE_LICENSE("GPL v2");