PCI: altera: Allow building as module

Altera PCIe Rootport IP is a soft IP and is only available after
an FPGA image (whose design contains it) is programmed.

Make driver modulable to support use cases when FPGA image is
programmed after the kernel has booted, so that the driver
can be loaded upon request.
Signed-off-by: Ley Foon Tan <ley.foon.tan@intel.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

drivers/pci/controller/Kconfig

@@ -174,7 +174,7 @@ config PCIE_IPROC_MSI
 	  PCIe controller
 
 config PCIE_ALTERA
-	bool "Altera PCIe controller"
+	tristate "Altera PCIe controller"
 	depends on ARM || NIOS2 || ARM64 || COMPILE_TEST
 	help
 	  Say Y here if you want to enable PCIe controller support on Altera

drivers/pci/controller/pcie-altera.c

@@ -10,6 +10,7 @@
 #include <linux/interrupt.h>
 #include <linux/irqchip/chained_irq.h>
 #include <linux/init.h>
+#include <linux/module.h>
 #include <linux/of_address.h>
 #include <linux/of_device.h>
 #include <linux/of_irq.h>
@@ -705,6 +706,13 @@ static int altera_pcie_init_irq_domain(struct altera_pcie *pcie)
 	return 0;
 }
 
+static void altera_pcie_irq_teardown(struct altera_pcie *pcie)
+{
+	irq_set_chained_handler_and_data(pcie->irq, NULL, NULL);
+	irq_domain_remove(pcie->irq_domain);
+	irq_dispose_mapping(pcie->irq);
+}
+
 static int altera_pcie_parse_dt(struct altera_pcie *pcie)
 {
 	struct device *dev = &pcie->pdev->dev;
@@ -798,6 +806,7 @@ static int altera_pcie_probe(struct platform_device *pdev)
 
 	pcie = pci_host_bridge_priv(bridge);
 	pcie->pdev = pdev;
+	platform_set_drvdata(pdev, pcie);
 
 	match = of_match_device(altera_pcie_of_match, &pdev->dev);
 	if (!match)
@@ -855,13 +864,28 @@ static int altera_pcie_probe(struct platform_device *pdev)
 	return ret;
 }
 
+static int altera_pcie_remove(struct platform_device *pdev)
+{
+	struct altera_pcie *pcie = platform_get_drvdata(pdev);
+	struct pci_host_bridge *bridge = pci_host_bridge_from_priv(pcie);
+
+	pci_stop_root_bus(bridge->bus);
+	pci_remove_root_bus(bridge->bus);
+	pci_free_resource_list(&pcie->resources);
+	altera_pcie_irq_teardown(pcie);
+
+	return 0;
+}
+
 static struct platform_driver altera_pcie_driver = {
 	.probe		= altera_pcie_probe,
+	.remove		= altera_pcie_remove,
 	.driver = {
 		.name	= "altera-pcie",
 		.of_match_table = altera_pcie_of_match,
-		.suppress_bind_attrs = true,
 	},
 };
 
-builtin_platform_driver(altera_pcie_driver);
+MODULE_DEVICE_TABLE(of, altera_pcie_of_match);
+module_platform_driver(altera_pcie_driver);
+MODULE_LICENSE("GPL v2");