text: /*
   * Persistent Memory Driver
   *
   * Copyright (c) 2014-2015, Intel Corporation.
   * Copyright (c) 2015, Christoph Hellwig <hch@lst.de>.
   * Copyright (c) 2015, Boaz Harrosh <boaz@plexistor.com>.
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   */
  
  #include <asm/cacheflush.h>
  #include <linux/blkdev.h>
  #include <linux/hdreg.h>
  #include <linux/init.h>
  #include <linux/platform_device.h>
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/slab.h>
  #include <linux/pmem.h>
  #include <linux/nd.h>
  #include "nd.h"
  
  struct pmem_device {
  	struct request_queue	*pmem_queue;
  	struct gendisk		*pmem_disk;
  
  	/* One contiguous memory region per device */
  	phys_addr_t		phys_addr;
  	void __pmem		*virt_addr;
  	size_t			size;
  };
  
  static int pmem_major;
  
  static void pmem_do_bvec(struct pmem_device *pmem, struct page *page,
  			unsigned int len, unsigned int off, int rw,
  			sector_t sector)
  {
  	void *mem = kmap_atomic(page);
  	size_t pmem_off = sector << 9;
  	void __pmem *pmem_addr = pmem->virt_addr + pmem_off;
  
  	if (rw == READ) {
  		memcpy_from_pmem(mem + off, pmem_addr, len);
  		flush_dcache_page(page);
  	} else {
  		flush_dcache_page(page);
  		memcpy_to_pmem(pmem_addr, mem + off, len);
  	}
  
  	kunmap_atomic(mem);
  }
  
  static void pmem_make_request(struct request_queue *q, struct bio *bio)
  {
  	bool do_acct;
  	unsigned long start;
  	struct bio_vec bvec;
  	struct bvec_iter iter;
  	struct block_device *bdev = bio->bi_bdev;
  	struct pmem_device *pmem = bdev->bd_disk->private_data;
  
  	do_acct = nd_iostat_start(bio, &start);
  	bio_for_each_segment(bvec, bio, iter)
  		pmem_do_bvec(pmem, bvec.bv_page, bvec.bv_len, bvec.bv_offset,
  				bio_data_dir(bio), iter.bi_sector);
  	if (do_acct)
  		nd_iostat_end(bio, start);
  
  	if (bio_data_dir(bio))
  		wmb_pmem();
  
  	bio_endio(bio, 0);
  }
  
  static int pmem_rw_page(struct block_device *bdev, sector_t sector,
  		       struct page *page, int rw)
  {
  	struct pmem_device *pmem = bdev->bd_disk->private_data;
  
  	pmem_do_bvec(pmem, page, PAGE_CACHE_SIZE, 0, rw, sector);
  	if (rw & WRITE)
  		wmb_pmem();
  	page_endio(page, rw & WRITE, 0);
  
  	return 0;
  }
  
  static long pmem_direct_access(struct block_device *bdev, sector_t sector,
  			      void **kaddr, unsigned long *pfn, long size)
  {
  	struct pmem_device *pmem = bdev->bd_disk->private_data;
  	size_t offset = sector << 9;
  
  	if (!pmem)
  		return -ENODEV;
  
  	/* FIXME convert DAX to comprehend that this mapping has a lifetime */
  	*kaddr = (void __force *) pmem->virt_addr + offset;
  	*pfn = (pmem->phys_addr + offset) >> PAGE_SHIFT;
  
  	return pmem->size - offset;
  }
  
  static const struct block_device_operations pmem_fops = {
  	.owner =		THIS_MODULE,
  	.rw_page =		pmem_rw_page,
  	.direct_access =	pmem_direct_access,
  	.revalidate_disk =	nvdimm_revalidate_disk,
  };
  
  static struct pmem_device *pmem_alloc(struct device *dev,
  		struct resource *res, int id)
  {
  	struct pmem_device *pmem;
  
  	pmem = kzalloc(sizeof(*pmem), GFP_KERNEL);
  	if (!pmem)
  		return ERR_PTR(-ENOMEM);
  
  	pmem->phys_addr = res->start;
  	pmem->size = resource_size(res);
  	if (!arch_has_pmem_api())
  		dev_warn(dev, "unable to guarantee persistence of writes\n");
  
  	if (!request_mem_region(pmem->phys_addr, pmem->size, dev_name(dev))) {
  		dev_warn(dev, "could not reserve region [0x%pa:0x%zx]\n",
  				&pmem->phys_addr, pmem->size);
  		kfree(pmem);
  		return ERR_PTR(-EBUSY);
  	}
  
  	pmem->virt_addr = memremap_pmem(pmem->phys_addr, pmem->size);
  	if (!pmem->virt_addr) {
  		release_mem_region(pmem->phys_addr, pmem->size);
  		kfree(pmem);
  		return ERR_PTR(-ENXIO);
  	}
  
  	return pmem;
  }
  
  static void pmem_detach_disk(struct pmem_device *pmem)
  {
  	del_gendisk(pmem->pmem_disk);
  	put_disk(pmem->pmem_disk);
  	blk_cleanup_queue(pmem->pmem_queue);
  }
  
  static int pmem_attach_disk(struct nd_namespace_common *ndns,
  		struct pmem_device *pmem)
  {
  	struct gendisk *disk;
  
  	pmem->pmem_queue = blk_alloc_queue(GFP_KERNEL);
  	if (!pmem->pmem_queue)
  		return -ENOMEM;
  
  	blk_queue_make_request(pmem->pmem_queue, pmem_make_request);
  	blk_queue_max_hw_sectors(pmem->pmem_queue, UINT_MAX);
  	blk_queue_bounce_limit(pmem->pmem_queue, BLK_BOUNCE_ANY);
  	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, pmem->pmem_queue);
  
  	disk = alloc_disk(0);
  	if (!disk) {
  		blk_cleanup_queue(pmem->pmem_queue);
  		return -ENOMEM;
  	}
  
  	disk->major		= pmem_major;
  	disk->first_minor	= 0;
  	disk->fops		= &pmem_fops;
  	disk->private_data	= pmem;
  	disk->queue		= pmem->pmem_queue;
  	disk->flags		= GENHD_FL_EXT_DEVT;
  	nvdimm_namespace_disk_name(ndns, disk->disk_name);
  	disk->driverfs_dev = &ndns->dev;
  	set_capacity(disk, pmem->size >> 9);
  	pmem->pmem_disk = disk;
  
  	add_disk(disk);
  	revalidate_disk(disk);
  
  	return 0;
  }
  
  static int pmem_rw_bytes(struct nd_namespace_common *ndns,
  		resource_size_t offset, void *buf, size_t size, int rw)
  {
  	struct pmem_device *pmem = dev_get_drvdata(ndns->claim);
  
  	if (unlikely(offset + size > pmem->size)) {
  		dev_WARN_ONCE(&ndns->dev, 1, "request out of range\n");
  		return -EFAULT;
  	}
  
  	if (rw == READ)
  		memcpy_from_pmem(buf, pmem->virt_addr + offset, size);
  	else {
  		memcpy_to_pmem(pmem->virt_addr + offset, buf, size);
  		wmb_pmem();
  	}
  
  	return 0;
  }
  
  static void pmem_free(struct pmem_device *pmem)
  {
  	memunmap_pmem(pmem->virt_addr);
  	release_mem_region(pmem->phys_addr, pmem->size);
  	kfree(pmem);
  }
  
  static int nd_pmem_probe(struct device *dev)
  {
  	struct nd_region *nd_region = to_nd_region(dev->parent);
  	struct nd_namespace_common *ndns;
  	struct nd_namespace_io *nsio;
  	struct pmem_device *pmem;
  	int rc;
  
  	ndns = nvdimm_namespace_common_probe(dev);
  	if (IS_ERR(ndns))
  		return PTR_ERR(ndns);
  
  	nsio = to_nd_namespace_io(&ndns->dev);
  	pmem = pmem_alloc(dev, &nsio->res, nd_region->id);
  	if (IS_ERR(pmem))
  		return PTR_ERR(pmem);
  
  	dev_set_drvdata(dev, pmem);
  	ndns->rw_bytes = pmem_rw_bytes;
  	if (is_nd_btt(dev))
  		rc = nvdimm_namespace_attach_btt(ndns);
  	else if (nd_btt_probe(ndns, pmem) == 0) {
  		/* we'll come back as btt-pmem */
  		rc = -ENXIO;
  	} else
  		rc = pmem_attach_disk(ndns, pmem);
  	if (rc)
  		pmem_free(pmem);
  	return rc;
  }
  
  static int nd_pmem_remove(struct device *dev)
  {
  	struct pmem_device *pmem = dev_get_drvdata(dev);
  
  	if (is_nd_btt(dev))
  		nvdimm_namespace_detach_btt(to_nd_btt(dev)->ndns);
  	else
  		pmem_detach_disk(pmem);
  	pmem_free(pmem);
  
  	return 0;
  }
  
  MODULE_ALIAS("pmem");
  MODULE_ALIAS_ND_DEVICE(ND_DEVICE_NAMESPACE_IO);
  MODULE_ALIAS_ND_DEVICE(ND_DEVICE_NAMESPACE_PMEM);
  static struct nd_device_driver nd_pmem_driver = {
  	.probe = nd_pmem_probe,
  	.remove = nd_pmem_remove,
  	.drv = {
  		.name = "nd_pmem",
  	},
  	.type = ND_DRIVER_NAMESPACE_IO | ND_DRIVER_NAMESPACE_PMEM,
  };
  
  static int __init pmem_init(void)
  {
  	int error;
  
  	pmem_major = register_blkdev(0, "pmem");
  	if (pmem_major < 0)
  		return pmem_major;
  
  	error = nd_driver_register(&nd_pmem_driver);
  	if (error) {
  		unregister_blkdev(pmem_major, "pmem");
  		return error;
  	}
  
  	return 0;
  }
  module_init(pmem_init);
  
  static void pmem_exit(void)
  {
  	driver_unregister(&nd_pmem_driver.drv);
  	unregister_blkdev(pmem_major, "pmem");
  }
  module_exit(pmem_exit);
  
  MODULE_AUTHOR("Ross Zwisler <ross.zwisler@linux.intel.com>");
  MODULE_LICENSE("GPL v2");
  