// SPDX-License-Identifier: GPL-2.0+
  
  #define pr_fmt(fmt) "of_pmem: " fmt
  
  #include <linux/of_platform.h>
  #include <linux/of_address.h>
  #include <linux/libnvdimm.h>
  #include <linux/module.h>
  #include <linux/ioport.h>
  #include <linux/slab.h>

  struct of_pmem_private {
  	struct nvdimm_bus_descriptor bus_desc;
  	struct nvdimm_bus *bus;
  };
  
  static int of_pmem_region_probe(struct platform_device *pdev)
  {
  	struct of_pmem_private *priv;
  	struct device_node *np;
  	struct nvdimm_bus *bus;
  	bool is_volatile;
  	int i;
  
  	np = dev_of_node(&pdev->dev);
  	if (!np)
  		return -ENXIO;
  
  	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
  	if (!priv)
  		return -ENOMEM;

  	priv->bus_desc.provider_name = kstrdup(pdev->name, GFP_KERNEL);

  	priv->bus_desc.module = THIS_MODULE;
  	priv->bus_desc.of_node = np;
  
  	priv->bus = bus = nvdimm_bus_register(&pdev->dev, &priv->bus_desc);
  	if (!bus) {
  		kfree(priv);
  		return -ENODEV;
  	}
  	platform_set_drvdata(pdev, priv);
  
  	is_volatile = !!of_find_property(np, "volatile", NULL);
  	dev_dbg(&pdev->dev, "Registering %s regions from %pOF
  ",
  			is_volatile ? "volatile" : "non-volatile",  np);
  
  	for (i = 0; i < pdev->num_resources; i++) {
  		struct nd_region_desc ndr_desc;
  		struct nd_region *region;
  
  		/*
  		 * NB: libnvdimm copies the data from ndr_desc into it's own
  		 * structures so passing a stack pointer is fine.
  		 */
  		memset(&ndr_desc, 0, sizeof(ndr_desc));

  		ndr_desc.numa_node = dev_to_node(&pdev->dev);

  		ndr_desc.target_node = ndr_desc.numa_node;

  		ndr_desc.res = &pdev->resource[i];
  		ndr_desc.of_node = np;
  		set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
  
  		if (is_volatile)
  			region = nvdimm_volatile_region_create(bus, &ndr_desc);

  		else {
  			set_bit(ND_REGION_PERSIST_MEMCTRL, &ndr_desc.flags);

  			region = nvdimm_pmem_region_create(bus, &ndr_desc);

  		}

  
  		if (!region)
  			dev_warn(&pdev->dev, "Unable to register region %pR from %pOF
  ",
  					ndr_desc.res, np);
  		else
  			dev_dbg(&pdev->dev, "Registered region %pR from %pOF
  ",
  					ndr_desc.res, np);
  	}
  
  	return 0;
  }
  
  static int of_pmem_region_remove(struct platform_device *pdev)
  {
  	struct of_pmem_private *priv = platform_get_drvdata(pdev);
  
  	nvdimm_bus_unregister(priv->bus);
  	kfree(priv);
  
  	return 0;
  }
  
  static const struct of_device_id of_pmem_region_match[] = {
  	{ .compatible = "pmem-region" },

  	{ .compatible = "pmem-region-v2" },

  	{ },
  };
  
  static struct platform_driver of_pmem_region_driver = {
  	.probe = of_pmem_region_probe,
  	.remove = of_pmem_region_remove,
  	.driver = {
  		.name = "of_pmem",

  		.of_match_table = of_pmem_region_match,
  	},
  };
  
  module_platform_driver(of_pmem_region_driver);
  MODULE_DEVICE_TABLE(of, of_pmem_region_match);
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("IBM Corporation");