text: // SPDX-License-Identifier: GPL-2.0
  /* Copyright(c) 2016 - 2018 Intel Corporation. All rights reserved. */
  #include <linux/memremap.h>
  #include <linux/module.h>
  #include <linux/pfn_t.h>
  #include "../../nvdimm/pfn.h"
  #include "../../nvdimm/nd.h"
  #include "../bus.h"
  
  struct dev_dax *__dax_pmem_probe(struct device *dev, enum dev_dax_subsys subsys)
  {
  	struct range range;
  	int rc, id, region_id;
  	resource_size_t offset;
  	struct nd_pfn_sb *pfn_sb;
  	struct dev_dax *dev_dax;
  	struct dev_dax_data data;
  	struct nd_namespace_io *nsio;
  	struct dax_region *dax_region;
  	struct dev_pagemap pgmap = { };
  	struct nd_namespace_common *ndns;
  	struct nd_dax *nd_dax = to_nd_dax(dev);
  	struct nd_pfn *nd_pfn = &nd_dax->nd_pfn;
  	struct nd_region *nd_region = to_nd_region(dev->parent);
  
  	ndns = nvdimm_namespace_common_probe(dev);
  	if (IS_ERR(ndns))
  		return ERR_CAST(ndns);
  
  	/* parse the 'pfn' info block via ->rw_bytes */
  	rc = devm_namespace_enable(dev, ndns, nd_info_block_reserve());
  	if (rc)
  		return ERR_PTR(rc);
  	rc = nvdimm_setup_pfn(nd_pfn, &pgmap);
  	if (rc)
  		return ERR_PTR(rc);
  	devm_namespace_disable(dev, ndns);
  
  	/* reserve the metadata area, device-dax will reserve the data */
  	pfn_sb = nd_pfn->pfn_sb;
  	offset = le64_to_cpu(pfn_sb->dataoff);
  	nsio = to_nd_namespace_io(&ndns->dev);
  	if (!devm_request_mem_region(dev, nsio->res.start, offset,
  				dev_name(&ndns->dev))) {
  		dev_warn(dev, "could not reserve metadata\n");
  		return ERR_PTR(-EBUSY);
  	}
  
  	rc = sscanf(dev_name(&ndns->dev), "namespace%d.%d", &region_id, &id);
  	if (rc != 2)
  		return ERR_PTR(-EINVAL);
  
  	/* adjust the dax_region range to the start of data */
  	range = pgmap.range;
  	range.start += offset;
  	dax_region = alloc_dax_region(dev, region_id, &range,
  			nd_region->target_node, le32_to_cpu(pfn_sb->align),
  			IORESOURCE_DAX_STATIC);
  	if (!dax_region)
  		return ERR_PTR(-ENOMEM);
  
  	data = (struct dev_dax_data) {
  		.dax_region = dax_region,
  		.id = id,
  		.pgmap = &pgmap,
  		.subsys = subsys,
  		.size = range_len(&range),
  	};
  	dev_dax = devm_create_dev_dax(&data);
  
  	/* child dev_dax instances now own the lifetime of the dax_region */
  	dax_region_put(dax_region);
  
  	return dev_dax;
  }
  EXPORT_SYMBOL_GPL(__dax_pmem_probe);
  
  MODULE_LICENSE("GPL v2");
  MODULE_AUTHOR("Intel Corporation");
  