// SPDX-License-Identifier: GPL-2.0-only

  /*
   * 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>.

   */

  #include <linux/blkdev.h>
  #include <linux/hdreg.h>
  #include <linux/init.h>
  #include <linux/platform_device.h>

  #include <linux/set_memory.h>

  #include <linux/module.h>
  #include <linux/moduleparam.h>

  #include <linux/badblocks.h>

  #include <linux/memremap.h>

  #include <linux/vmalloc.h>

  #include <linux/blk-mq.h>

  #include <linux/pfn_t.h>

  #include <linux/slab.h>

  #include <linux/uio.h>

  #include <linux/dax.h>

  #include <linux/nd.h>

  #include <linux/backing-dev.h>

  #include <linux/mm.h>
  #include <asm/cacheflush.h>

  #include "pmem.h"

  #include "pfn.h"

  #include "nd.h"

  static struct device *to_dev(struct pmem_device *pmem)
  {
  	/*
  	 * nvdimm bus services need a 'dev' parameter, and we record the device
  	 * at init in bb.dev.
  	 */
  	return pmem->bb.dev;
  }
  
  static struct nd_region *to_region(struct pmem_device *pmem)
  {
  	return to_nd_region(to_dev(pmem)->parent);
  }

  static void hwpoison_clear(struct pmem_device *pmem,
  		phys_addr_t phys, unsigned int len)
  {
  	unsigned long pfn_start, pfn_end, pfn;
  
  	/* only pmem in the linear map supports HWPoison */
  	if (is_vmalloc_addr(pmem->virt_addr))
  		return;
  
  	pfn_start = PHYS_PFN(phys);
  	pfn_end = pfn_start + PHYS_PFN(len);
  	for (pfn = pfn_start; pfn < pfn_end; pfn++) {
  		struct page *page = pfn_to_page(pfn);
  
  		/*
  		 * Note, no need to hold a get_dev_pagemap() reference
  		 * here since we're in the driver I/O path and
  		 * outstanding I/O requests pin the dev_pagemap.
  		 */
  		if (test_and_clear_pmem_poison(page))
  			clear_mce_nospec(pfn);
  	}
  }

  static blk_status_t pmem_clear_poison(struct pmem_device *pmem,
  		phys_addr_t offset, unsigned int len)

  {

  	struct device *dev = to_dev(pmem);

  	sector_t sector;
  	long cleared;

  	blk_status_t rc = BLK_STS_OK;

  
  	sector = (offset - pmem->data_offset) / 512;

  	cleared = nvdimm_clear_poison(dev, pmem->phys_addr + offset, len);
  	if (cleared < len)

  		rc = BLK_STS_IOERR;

  	if (cleared > 0 && cleared / 512) {

  		hwpoison_clear(pmem, pmem->phys_addr + offset, cleared);

  		cleared /= 512;

  		dev_dbg(dev, "%#llx clear %ld sector%s
  ",

  				(unsigned long long) sector, cleared,
  				cleared > 1 ? "s" : "");

  		badblocks_clear(&pmem->bb, sector, cleared);

  		if (pmem->bb_state)
  			sysfs_notify_dirent(pmem->bb_state);

  	}

  	arch_invalidate_pmem(pmem->virt_addr + offset, len);

  
  	return rc;

  }

  static void write_pmem(void *pmem_addr, struct page *page,
  		unsigned int off, unsigned int len)
  {

  	unsigned int chunk;
  	void *mem;
  
  	while (len) {
  		mem = kmap_atomic(page);

  		chunk = min_t(unsigned int, len, PAGE_SIZE - off);

  		memcpy_flushcache(pmem_addr, mem + off, chunk);
  		kunmap_atomic(mem);
  		len -= chunk;
  		off = 0;
  		page++;

  		pmem_addr += chunk;

  	}

  }

  static blk_status_t read_pmem(struct page *page, unsigned int off,

  		void *pmem_addr, unsigned int len)
  {

  	unsigned int chunk;

  	unsigned long rem;

  	void *mem;
  
  	while (len) {
  		mem = kmap_atomic(page);

  		chunk = min_t(unsigned int, len, PAGE_SIZE - off);

  		rem = copy_mc_to_kernel(mem + off, pmem_addr, chunk);

  		kunmap_atomic(mem);

  		if (rem)

  			return BLK_STS_IOERR;
  		len -= chunk;
  		off = 0;
  		page++;

  		pmem_addr += chunk;

  	}

  	return BLK_STS_OK;

  }

  static blk_status_t pmem_do_read(struct pmem_device *pmem,
  			struct page *page, unsigned int page_off,
  			sector_t sector, unsigned int len)
  {
  	blk_status_t rc;
  	phys_addr_t pmem_off = sector * 512 + pmem->data_offset;
  	void *pmem_addr = pmem->virt_addr + pmem_off;
  
  	if (unlikely(is_bad_pmem(&pmem->bb, sector, len)))
  		return BLK_STS_IOERR;
  
  	rc = read_pmem(page, page_off, pmem_addr, len);
  	flush_dcache_page(page);
  	return rc;
  }
  
  static blk_status_t pmem_do_write(struct pmem_device *pmem,
  			struct page *page, unsigned int page_off,
  			sector_t sector, unsigned int len)

  {

  	blk_status_t rc = BLK_STS_OK;

  	bool bad_pmem = false;

  	phys_addr_t pmem_off = sector * 512 + pmem->data_offset;

  	void *pmem_addr = pmem->virt_addr + pmem_off;

  	if (unlikely(is_bad_pmem(&pmem->bb, sector, len)))
  		bad_pmem = true;

  	/*
  	 * Note that we write the data both before and after
  	 * clearing poison.  The write before clear poison
  	 * handles situations where the latest written data is
  	 * preserved and the clear poison operation simply marks
  	 * the address range as valid without changing the data.
  	 * In this case application software can assume that an
  	 * interrupted write will either return the new good
  	 * data or an error.
  	 *
  	 * However, if pmem_clear_poison() leaves the data in an
  	 * indeterminate state we need to perform the write
  	 * after clear poison.
  	 */
  	flush_dcache_page(page);
  	write_pmem(pmem_addr, page, page_off, len);
  	if (unlikely(bad_pmem)) {
  		rc = pmem_clear_poison(pmem, pmem_off, len);
  		write_pmem(pmem_addr, page, page_off, len);

  	}

  	return rc;

  }

  static blk_qc_t pmem_submit_bio(struct bio *bio)

  {

  	int ret = 0;

  	blk_status_t rc = 0;

  	bool do_acct;
  	unsigned long start;

  	struct bio_vec bvec;

  	struct bvec_iter iter;

  	struct pmem_device *pmem = bio->bi_disk->private_data;

  	struct nd_region *nd_region = to_region(pmem);

  	if (bio->bi_opf & REQ_PREFLUSH)

  		ret = nvdimm_flush(nd_region, bio);

  	do_acct = blk_queue_io_stat(bio->bi_disk->queue);
  	if (do_acct)
  		start = bio_start_io_acct(bio);

  	bio_for_each_segment(bvec, bio, iter) {

  		if (op_is_write(bio_op(bio)))
  			rc = pmem_do_write(pmem, bvec.bv_page, bvec.bv_offset,
  				iter.bi_sector, bvec.bv_len);
  		else
  			rc = pmem_do_read(pmem, bvec.bv_page, bvec.bv_offset,
  				iter.bi_sector, bvec.bv_len);

  		if (rc) {

  			bio->bi_status = rc;

  			break;
  		}
  	}

  	if (do_acct)

  		bio_end_io_acct(bio, start);

  	if (bio->bi_opf & REQ_FUA)

  		ret = nvdimm_flush(nd_region, bio);
  
  	if (ret)
  		bio->bi_status = errno_to_blk_status(ret);

  	bio_endio(bio);

  	return BLK_QC_T_NONE;

  }
  
  static int pmem_rw_page(struct block_device *bdev, sector_t sector,

  		       struct page *page, unsigned int op)

  {

  	struct pmem_device *pmem = bdev->bd_disk->private_data;

  	blk_status_t rc;

  	if (op_is_write(op))

  		rc = pmem_do_write(pmem, page, 0, sector, thp_size(page));

  	else

  		rc = pmem_do_read(pmem, page, 0, sector, thp_size(page));

  	/*
  	 * The ->rw_page interface is subtle and tricky.  The core
  	 * retries on any error, so we can only invoke page_endio() in
  	 * the successful completion case.  Otherwise, we'll see crashes
  	 * caused by double completion.
  	 */
  	if (rc == 0)

  		page_endio(page, op_is_write(op), 0);

  	return blk_status_to_errno(rc);

  }

  /* see "strong" declaration in tools/testing/nvdimm/pmem-dax.c */

  __weak long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
  		long nr_pages, void **kaddr, pfn_t *pfn)

  {

  	resource_size_t offset = PFN_PHYS(pgoff) + pmem->data_offset;

  	if (unlikely(is_bad_pmem(&pmem->bb, PFN_PHYS(pgoff) / 512,
  					PFN_PHYS(nr_pages))))

  		return -EIO;

  
  	if (kaddr)
  		*kaddr = pmem->virt_addr + offset;
  	if (pfn)
  		*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);

  	/*
  	 * If badblocks are present, limit known good range to the
  	 * requested range.
  	 */
  	if (unlikely(pmem->bb.count))

  		return nr_pages;
  	return PHYS_PFN(pmem->size - pmem->pfn_pad - offset);

  }
  
  static const struct block_device_operations pmem_fops = {
  	.owner =		THIS_MODULE,

  	.submit_bio =		pmem_submit_bio,

  	.rw_page =		pmem_rw_page,

  };

  static int pmem_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
  				    size_t nr_pages)
  {
  	struct pmem_device *pmem = dax_get_private(dax_dev);
  
  	return blk_status_to_errno(pmem_do_write(pmem, ZERO_PAGE(0), 0,
  				   PFN_PHYS(pgoff) >> SECTOR_SHIFT,
  				   PAGE_SIZE));
  }

  static long pmem_dax_direct_access(struct dax_device *dax_dev,
  		pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn)
  {
  	struct pmem_device *pmem = dax_get_private(dax_dev);
  
  	return __pmem_direct_access(pmem, pgoff, nr_pages, kaddr, pfn);
  }

  /*
   * Use the 'no check' versions of copy_from_iter_flushcache() and

   * copy_mc_to_iter() to bypass HARDENED_USERCOPY overhead. Bounds

   * checking, both file offset and device offset, is handled by
   * dax_iomap_actor()
   */

  static size_t pmem_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
  		void *addr, size_t bytes, struct iov_iter *i)
  {

  	return _copy_from_iter_flushcache(addr, bytes, i);

  }

  static size_t pmem_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
  		void *addr, size_t bytes, struct iov_iter *i)
  {

  	return _copy_mc_to_iter(addr, bytes, i);

  }

  static const struct dax_operations pmem_dax_ops = {
  	.direct_access = pmem_dax_direct_access,

  	.dax_supported = generic_fsdax_supported,

  	.copy_from_iter = pmem_copy_from_iter,

  	.copy_to_iter = pmem_copy_to_iter,

  	.zero_page_range = pmem_dax_zero_page_range,

  };

  static const struct attribute_group *pmem_attribute_groups[] = {
  	&dax_attribute_group,
  	NULL,

  };

  static void pmem_pagemap_cleanup(struct dev_pagemap *pgmap)

  {

  	struct request_queue *q =
  		container_of(pgmap->ref, struct request_queue, q_usage_counter);

  	blk_cleanup_queue(q);
  }

  static void pmem_release_queue(void *pgmap)

  {

  	pmem_pagemap_cleanup(pgmap);

  }

  static void pmem_pagemap_kill(struct dev_pagemap *pgmap)

  {

  	struct request_queue *q =
  		container_of(pgmap->ref, struct request_queue, q_usage_counter);

  	blk_freeze_queue_start(q);

  }

  static void pmem_release_disk(void *__pmem)

  {

  	struct pmem_device *pmem = __pmem;
  
  	kill_dax(pmem->dax_dev);
  	put_dax(pmem->dax_dev);
  	del_gendisk(pmem->disk);
  	put_disk(pmem->disk);

  }

  static const struct dev_pagemap_ops fsdax_pagemap_ops = {

  	.kill			= pmem_pagemap_kill,
  	.cleanup		= pmem_pagemap_cleanup,
  };

  static int pmem_attach_disk(struct device *dev,
  		struct nd_namespace_common *ndns)

  {

  	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);

  	struct nd_region *nd_region = to_nd_region(dev->parent);

  	int nid = dev_to_node(dev), fua;

  	struct resource *res = &nsio->res;

  	struct range bb_range;

  	struct nd_pfn *nd_pfn = NULL;

  	struct dax_device *dax_dev;

  	struct nd_pfn_sb *pfn_sb;

  	struct pmem_device *pmem;

  	struct request_queue *q;

  	struct device *gendev;

  	struct gendisk *disk;
  	void *addr;

  	int rc;

  	unsigned long flags = 0UL;

  
  	pmem = devm_kzalloc(dev, sizeof(*pmem), GFP_KERNEL);
  	if (!pmem)
  		return -ENOMEM;

  	rc = devm_namespace_enable(dev, ndns, nd_info_block_reserve());
  	if (rc)
  		return rc;

  	/* while nsio_rw_bytes is active, parse a pfn info block if present */
  	if (is_nd_pfn(dev)) {
  		nd_pfn = to_nd_pfn(dev);

  		rc = nvdimm_setup_pfn(nd_pfn, &pmem->pgmap);
  		if (rc)
  			return rc;

  	}
  
  	/* we're attaching a block device, disable raw namespace access */

  	devm_namespace_disable(dev, ndns);

  	dev_set_drvdata(dev, pmem);

  	pmem->phys_addr = res->start;
  	pmem->size = resource_size(res);

  	fua = nvdimm_has_flush(nd_region);
  	if (!IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) || fua < 0) {

  		dev_warn(dev, "unable to guarantee persistence of writes
  ");

  		fua = 0;
  	}

  	if (!devm_request_mem_region(dev, res->start, resource_size(res),

  				dev_name(&ndns->dev))) {

  		dev_warn(dev, "could not reserve region %pR
  ", res);

  		return -EBUSY;

  	}

  	q = blk_alloc_queue(dev_to_node(dev));

  	if (!q)

  		return -ENOMEM;

  	pmem->pfn_flags = PFN_DEV;

  	pmem->pgmap.ref = &q->q_usage_counter;

  	if (is_nd_pfn(dev)) {

  		pmem->pgmap.type = MEMORY_DEVICE_FS_DAX;
  		pmem->pgmap.ops = &fsdax_pagemap_ops;

  		addr = devm_memremap_pages(dev, &pmem->pgmap);

  		pfn_sb = nd_pfn->pfn_sb;
  		pmem->data_offset = le64_to_cpu(pfn_sb->dataoff);

  		pmem->pfn_pad = resource_size(res) -

  			range_len(&pmem->pgmap.range);

  		pmem->pfn_flags |= PFN_MAP;

  		bb_range = pmem->pgmap.range;
  		bb_range.start += pmem->data_offset;

  	} else if (pmem_should_map_pages(dev)) {

  		pmem->pgmap.range.start = res->start;
  		pmem->pgmap.range.end = res->end;

  		pmem->pgmap.nr_range = 1;

  		pmem->pgmap.type = MEMORY_DEVICE_FS_DAX;
  		pmem->pgmap.ops = &fsdax_pagemap_ops;

  		addr = devm_memremap_pages(dev, &pmem->pgmap);

  		pmem->pfn_flags |= PFN_MAP;

  		bb_range = pmem->pgmap.range;

  	} else {

  		if (devm_add_action_or_reset(dev, pmem_release_queue,

  					&pmem->pgmap))

  			return -ENOMEM;

  		addr = devm_memremap(dev, pmem->phys_addr,
  				pmem->size, ARCH_MEMREMAP_PMEM);

  		bb_range.start =  res->start;
  		bb_range.end = res->end;

  	}

  	if (IS_ERR(addr))
  		return PTR_ERR(addr);

  	pmem->virt_addr = addr;

  	blk_queue_write_cache(q, true, fua);

  	blk_queue_physical_block_size(q, PAGE_SIZE);

  	blk_queue_logical_block_size(q, pmem_sector_size(ndns));

  	blk_queue_max_hw_sectors(q, UINT_MAX);

  	blk_queue_flag_set(QUEUE_FLAG_NONROT, q);

  	if (pmem->pfn_flags & PFN_MAP)
  		blk_queue_flag_set(QUEUE_FLAG_DAX, q);

  	disk = alloc_disk_node(0, nid);

  	if (!disk)
  		return -ENOMEM;

  	pmem->disk = disk;

  	disk->fops		= &pmem_fops;

  	disk->queue		= q;

  	disk->flags		= GENHD_FL_EXT_DEVT;

  	disk->private_data	= pmem;

  	nvdimm_namespace_disk_name(ndns, disk->disk_name);

  	set_capacity(disk, (pmem->size - pmem->pfn_pad - pmem->data_offset)
  			/ 512);

  	if (devm_init_badblocks(dev, &pmem->bb))
  		return -ENOMEM;

  	nvdimm_badblocks_populate(nd_region, &pmem->bb, &bb_range);

  	disk->bb = &pmem->bb;

  	if (is_nvdimm_sync(nd_region))
  		flags = DAXDEV_F_SYNC;
  	dax_dev = alloc_dax(pmem, disk->disk_name, &pmem_dax_ops, flags);

  	if (IS_ERR(dax_dev)) {

  		put_disk(disk);

  		return PTR_ERR(dax_dev);

  	}

  	dax_write_cache(dax_dev, nvdimm_has_cache(nd_region));

  	pmem->dax_dev = dax_dev;

  	gendev = disk_to_dev(disk);
  	gendev->groups = pmem_attribute_groups;

  	device_add_disk(dev, disk, NULL);

  	if (devm_add_action_or_reset(dev, pmem_release_disk, pmem))

  		return -ENOMEM;

  	nvdimm_check_and_set_ro(disk);

  	pmem->bb_state = sysfs_get_dirent(disk_to_dev(disk)->kobj.sd,
  					  "badblocks");

  	if (!pmem->bb_state)
  		dev_warn(dev, "'badblocks' notification disabled
  ");

  	return 0;
  }

  static int nd_pmem_probe(struct device *dev)

  {

  	int ret;

  	struct nd_namespace_common *ndns;

  	ndns = nvdimm_namespace_common_probe(dev);
  	if (IS_ERR(ndns))
  		return PTR_ERR(ndns);

  	if (is_nd_btt(dev))

  		return nvdimm_namespace_attach_btt(ndns);

  	if (is_nd_pfn(dev))

  		return pmem_attach_disk(dev, ndns);

  	ret = devm_namespace_enable(dev, ndns, nd_info_block_reserve());
  	if (ret)
  		return ret;

  	ret = nd_btt_probe(dev, ndns);
  	if (ret == 0)

  		return -ENXIO;

  	/*
  	 * We have two failure conditions here, there is no
  	 * info reserver block or we found a valid info reserve block
  	 * but failed to initialize the pfn superblock.
  	 *
  	 * For the first case consider namespace as a raw pmem namespace
  	 * and attach a disk.
  	 *
  	 * For the latter, consider this a success and advance the namespace
  	 * seed.
  	 */
  	ret = nd_pfn_probe(dev, ndns);
  	if (ret == 0)
  		return -ENXIO;
  	else if (ret == -EOPNOTSUPP)
  		return ret;
  
  	ret = nd_dax_probe(dev, ndns);
  	if (ret == 0)
  		return -ENXIO;
  	else if (ret == -EOPNOTSUPP)
  		return ret;

  
  	/* probe complete, attach handles namespace enabling */
  	devm_namespace_disable(dev, ndns);

  	return pmem_attach_disk(dev, ndns);

  }

  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));

  	else {
  		/*

  		 * Note, this assumes nd_device_lock() context to not
  		 * race nd_pmem_notify()

  		 */
  		sysfs_put(pmem->bb_state);
  		pmem->bb_state = NULL;
  	}

  	nvdimm_flush(to_nd_region(dev->parent), NULL);

  	return 0;
  }

  static void nd_pmem_shutdown(struct device *dev)
  {

  	nvdimm_flush(to_nd_region(dev->parent), NULL);

  }

  static void nd_pmem_notify(struct device *dev, enum nvdimm_event event)
  {

  	struct nd_region *nd_region;

  	resource_size_t offset = 0, end_trunc = 0;
  	struct nd_namespace_common *ndns;
  	struct nd_namespace_io *nsio;

  	struct badblocks *bb;

  	struct range range;

  	struct kernfs_node *bb_state;

  
  	if (event != NVDIMM_REVALIDATE_POISON)
  		return;

  	if (is_nd_btt(dev)) {
  		struct nd_btt *nd_btt = to_nd_btt(dev);
  
  		ndns = nd_btt->ndns;

  		nd_region = to_nd_region(ndns->dev.parent);
  		nsio = to_nd_namespace_io(&ndns->dev);
  		bb = &nsio->bb;

  		bb_state = NULL;

  	} else {
  		struct pmem_device *pmem = dev_get_drvdata(dev);

  		nd_region = to_region(pmem);
  		bb = &pmem->bb;

  		bb_state = pmem->bb_state;

  
  		if (is_nd_pfn(dev)) {
  			struct nd_pfn *nd_pfn = to_nd_pfn(dev);
  			struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
  
  			ndns = nd_pfn->ndns;
  			offset = pmem->data_offset +
  					__le32_to_cpu(pfn_sb->start_pad);
  			end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
  		} else {
  			ndns = to_ndns(dev);
  		}
  
  		nsio = to_nd_namespace_io(&ndns->dev);
  	}

  	range.start = nsio->res.start + offset;
  	range.end = nsio->res.end - end_trunc;
  	nvdimm_badblocks_populate(nd_region, bb, &range);

  	if (bb_state)
  		sysfs_notify_dirent(bb_state);

  }

  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,

  	.notify = nd_pmem_notify,

  	.shutdown = nd_pmem_shutdown,

  	.drv = {
  		.name = "nd_pmem",

  	},

  	.type = ND_DRIVER_NAMESPACE_IO | ND_DRIVER_NAMESPACE_PMEM,

  };

  module_nd_driver(nd_pmem_driver);

  
  MODULE_AUTHOR("Ross Zwisler <ross.zwisler@linux.intel.com>");
  MODULE_LICENSE("GPL v2");