PCI: controller: Add VF driver support

Add tegra PCIe VF driver support from Nvidia repo

Bug 3583632

Change-Id: I323ae5a7aaa20647bfd80404bc354a5a52097cce
Signed-off-by: Nagarjuna Kristam <nkristam@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/2736248
Reviewed-by: Laxman Dewangan <ldewangan@nvidia.com>
GVS: Gerrit_Virtual_Submit

drivers/pci/controller/Makefile

@@ -2,3 +2,4 @@
 # Copyright (c) 2022, NVIDIA CORPORATION.  All rights reserved.
 
 obj-m += tegra-pcie-edma.o
+obj-m += pcie-tegra-vf.o

drivers/pci/controller/pcie-tegra-vf.c

@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PCIe driver to enumerate PCIe virtual functions in VM.
+ *
+ * Copyright (C) 2021-2022, NVIDIA Corporation. All rights reserved.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/pci-ecam.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+
+static void pci_tegra_vf_ecam_free(void *ptr)
+{
+	pci_ecam_free((struct pci_config_window *)ptr);
+}
+
+static struct pci_config_window *pci_tegra_vf_ecam_init(struct device *dev,
+		struct pci_host_bridge *bridge, const struct pci_ecam_ops *ops)
+{
+	struct resource cfgres;
+	struct pci_config_window *cfg;
+	static struct resource busn_res = {
+		.start = 0,
+		.end = 255,
+		.flags = IORESOURCE_BUS,
+	};
+	int err;
+
+	err = of_address_to_resource(dev->of_node, 0, &cfgres);
+	if (err) {
+		dev_err(dev, "missing \"reg\" property\n");
+		return ERR_PTR(err);
+	}
+
+	cfg = pci_ecam_create(dev, &cfgres, &busn_res, ops);
+	if (IS_ERR(cfg)) {
+		dev_err(dev, "pci_ecam_create() failed\n");
+		return cfg;
+	}
+
+	err = devm_add_action_or_reset(dev, pci_tegra_vf_ecam_free, cfg);
+	if (err) {
+		dev_err(dev, "devm_add_action_or_reset() failed\n");
+		return ERR_PTR(err);
+	}
+
+	return cfg;
+}
+
+static int pci_tegra_vf_claim_resource(struct pci_dev *dev, void *data)
+{
+	int i;
+	struct resource *res;
+
+	for (i = 0; i < PCI_NUM_RESOURCES; i++) {
+		res = &dev->resource[i];
+
+		if (!res->parent && res->start && res->flags)
+			if (pci_claim_resource(dev, i))
+				dev_err(&dev->dev, "can't claim resource %pR\n",
+					res);
+	}
+
+	return 0;
+}
+
+static int pci_tegra_vf_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct pci_host_bridge *bridge;
+	struct pci_config_window *cfg;
+	struct pci_bus *bus;
+	LIST_HEAD(resources);
+	static struct resource busn_res = {
+		.start = 0,
+		.end = 255,
+		.flags = IORESOURCE_BUS,
+	};
+
+	bridge = pci_alloc_host_bridge(0);
+	if (!bridge) {
+		dev_err(dev, "pci_alloc_host_bridge() failed\n");
+		return -ENOMEM;
+	}
+
+	/* Parse and map our Configuration Space windows */
+	cfg = pci_tegra_vf_ecam_init(dev, bridge, &pci_generic_ecam_ops);
+	if (IS_ERR(cfg)) {
+		dev_err(dev, "pci_tegra_vf_ecam_init() failed\n");
+		return PTR_ERR(cfg);
+	}
+
+	bridge->sysdata = cfg;
+	bridge->ops = (struct pci_ops *)&pci_generic_ecam_ops.pci_ops;
+
+	platform_set_drvdata(pdev, bridge);
+
+	pci_add_resource(&resources, &ioport_resource);
+	pci_add_resource(&resources, &iomem_resource);
+	pci_add_resource(&resources, &busn_res);
+
+	pci_lock_rescan_remove();
+
+	bus = pci_scan_root_bus(dev, 0, bridge->ops, cfg, &resources);
+	if (!bus) {
+		dev_err(dev, "pci_scan_root_bus() failed\n");
+		pci_unlock_rescan_remove();
+		pci_free_resource_list(&resources);
+		return -ENOMEM;
+	}
+
+	pci_walk_bus(bus, pci_tegra_vf_claim_resource, pdev);
+
+	pci_bus_add_devices(bus);
+
+	pci_unlock_rescan_remove();
+
+	return 0;
+}
+
+static int pci_tegra_vf_remove(struct platform_device *pdev)
+{
+	struct pci_host_bridge *bridge = platform_get_drvdata(pdev);
+
+	pci_lock_rescan_remove();
+	pci_stop_root_bus(bridge->bus);
+	pci_remove_root_bus(bridge->bus);
+	pci_unlock_rescan_remove();
+
+	return 0;
+}
+
+static const struct of_device_id pci_tegra_vf_of_match[] = {
+	{ .compatible = "pcie-tegra-vf", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, pci_tegra_vf_of_match);
+
+static struct platform_driver pci_tegra_vf_driver = {
+	.driver = {
+		.name = "pcie-tegra-vf",
+		.of_match_table = pci_tegra_vf_of_match,
+	},
+	.probe = pci_tegra_vf_probe,
+	.remove = pci_tegra_vf_remove,
+};
+module_platform_driver(pci_tegra_vf_driver);
+
+MODULE_DESCRIPTION("PCIe driver to enumerate PCIe virtual functions in VM");
+MODULE_AUTHOR("Manikanta Maddireddy <mmaddireddy@nvidia.com>");
+MODULE_LICENSE("GPL v2");