/*
   * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of version 2 of the GNU General Public License as
   * published by the Free Software Foundation.
   *
   * This program is distributed in the hope that 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 <linux/device.h>
  #include <linux/sizes.h>
  #include "nd-core.h"

  #include "pmem.h"

  #include "pfn.h"
  #include "btt.h"
  #include "nd.h"
  
  void __nd_detach_ndns(struct device *dev, struct nd_namespace_common **_ndns)
  {
  	struct nd_namespace_common *ndns = *_ndns;

  	struct nvdimm_bus *nvdimm_bus;

  	if (!ndns)
  		return;
  
  	nvdimm_bus = walk_to_nvdimm_bus(&ndns->dev);
  	lockdep_assert_held(&nvdimm_bus->reconfig_mutex);

  	dev_WARN_ONCE(dev, ndns->claim != dev, "%s: invalid claim
  ", __func__);

  	ndns->claim = NULL;
  	*_ndns = NULL;
  	put_device(&ndns->dev);
  }
  
  void nd_detach_ndns(struct device *dev,
  		struct nd_namespace_common **_ndns)
  {
  	struct nd_namespace_common *ndns = *_ndns;
  
  	if (!ndns)
  		return;
  	get_device(&ndns->dev);

  	nvdimm_bus_lock(&ndns->dev);

  	__nd_detach_ndns(dev, _ndns);

  	nvdimm_bus_unlock(&ndns->dev);

  	put_device(&ndns->dev);
  }
  
  bool __nd_attach_ndns(struct device *dev, struct nd_namespace_common *attach,
  		struct nd_namespace_common **_ndns)
  {

  	struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(&attach->dev);

  	if (attach->claim)
  		return false;

  	lockdep_assert_held(&nvdimm_bus->reconfig_mutex);

  	dev_WARN_ONCE(dev, *_ndns, "%s: invalid claim
  ", __func__);

  	attach->claim = dev;
  	*_ndns = attach;
  	get_device(&attach->dev);
  	return true;
  }
  
  bool nd_attach_ndns(struct device *dev, struct nd_namespace_common *attach,
  		struct nd_namespace_common **_ndns)
  {
  	bool claimed;

  	nvdimm_bus_lock(&attach->dev);

  	claimed = __nd_attach_ndns(dev, attach, _ndns);

  	nvdimm_bus_unlock(&attach->dev);

  	return claimed;
  }
  
  static int namespace_match(struct device *dev, void *data)
  {
  	char *name = data;
  
  	return strcmp(name, dev_name(dev)) == 0;
  }
  
  static bool is_idle(struct device *dev, struct nd_namespace_common *ndns)
  {
  	struct nd_region *nd_region = to_nd_region(dev->parent);
  	struct device *seed = NULL;
  
  	if (is_nd_btt(dev))
  		seed = nd_region->btt_seed;
  	else if (is_nd_pfn(dev))
  		seed = nd_region->pfn_seed;

  	else if (is_nd_dax(dev))
  		seed = nd_region->dax_seed;

  
  	if (seed == dev || ndns || dev->driver)
  		return false;
  	return true;
  }

  struct nd_pfn *to_nd_pfn_safe(struct device *dev)
  {
  	/*
  	 * pfn device attributes are re-used by dax device instances, so we
  	 * need to be careful to correct device-to-nd_pfn conversion.
  	 */
  	if (is_nd_pfn(dev))
  		return to_nd_pfn(dev);
  
  	if (is_nd_dax(dev)) {
  		struct nd_dax *nd_dax = to_nd_dax(dev);
  
  		return &nd_dax->nd_pfn;
  	}
  
  	WARN_ON(1);
  	return NULL;
  }

  static void nd_detach_and_reset(struct device *dev,
  		struct nd_namespace_common **_ndns)
  {
  	/* detach the namespace and destroy / reset the device */

  	__nd_detach_ndns(dev, _ndns);

  	if (is_idle(dev, *_ndns)) {
  		nd_device_unregister(dev, ND_ASYNC);
  	} else if (is_nd_btt(dev)) {
  		struct nd_btt *nd_btt = to_nd_btt(dev);
  
  		nd_btt->lbasize = 0;
  		kfree(nd_btt->uuid);
  		nd_btt->uuid = NULL;

  	} else if (is_nd_pfn(dev) || is_nd_dax(dev)) {
  		struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);

  
  		kfree(nd_pfn->uuid);
  		nd_pfn->uuid = NULL;
  		nd_pfn->mode = PFN_MODE_NONE;
  	}
  }
  
  ssize_t nd_namespace_store(struct device *dev,
  		struct nd_namespace_common **_ndns, const char *buf,
  		size_t len)
  {
  	struct nd_namespace_common *ndns;
  	struct device *found;
  	char *name;
  
  	if (dev->driver) {
  		dev_dbg(dev, "%s: -EBUSY
  ", __func__);
  		return -EBUSY;
  	}
  
  	name = kstrndup(buf, len, GFP_KERNEL);
  	if (!name)
  		return -ENOMEM;
  	strim(name);
  
  	if (strncmp(name, "namespace", 9) == 0 || strcmp(name, "") == 0)
  		/* pass */;
  	else {
  		len = -EINVAL;
  		goto out;
  	}
  
  	ndns = *_ndns;
  	if (strcmp(name, "") == 0) {
  		nd_detach_and_reset(dev, _ndns);
  		goto out;
  	} else if (ndns) {
  		dev_dbg(dev, "namespace already set to: %s
  ",
  				dev_name(&ndns->dev));
  		len = -EBUSY;
  		goto out;
  	}
  
  	found = device_find_child(dev->parent, name, namespace_match);
  	if (!found) {
  		dev_dbg(dev, "'%s' not found under %s
  ", name,
  				dev_name(dev->parent));
  		len = -ENODEV;
  		goto out;
  	}
  
  	ndns = to_ndns(found);

  
  	switch (ndns->claim_class) {
  	case NVDIMM_CCLASS_NONE:
  		break;
  	case NVDIMM_CCLASS_BTT:

  	case NVDIMM_CCLASS_BTT2:

  		if (!is_nd_btt(dev)) {
  			len = -EBUSY;
  			goto out_attach;
  		}
  		break;
  	case NVDIMM_CCLASS_PFN:
  		if (!is_nd_pfn(dev)) {
  			len = -EBUSY;
  			goto out_attach;
  		}
  		break;
  	case NVDIMM_CCLASS_DAX:
  		if (!is_nd_dax(dev)) {
  			len = -EBUSY;
  			goto out_attach;
  		}
  		break;
  	default:
  		len = -EBUSY;
  		goto out_attach;
  		break;
  	}

  	if (__nvdimm_namespace_capacity(ndns) < SZ_16M) {
  		dev_dbg(dev, "%s too small to host
  ", name);
  		len = -ENXIO;
  		goto out_attach;
  	}
  
  	WARN_ON_ONCE(!is_nvdimm_bus_locked(dev));

  	if (!__nd_attach_ndns(dev, ndns, _ndns)) {

  		dev_dbg(dev, "%s already claimed
  ",
  				dev_name(&ndns->dev));
  		len = -EBUSY;
  	}
  
   out_attach:
  	put_device(&ndns->dev); /* from device_find_child */
   out:
  	kfree(name);
  	return len;
  }
  
  /*
   * nd_sb_checksum: compute checksum for a generic info block
   *
   * Returns a fletcher64 checksum of everything in the given info block
   * except the last field (since that's where the checksum lives).
   */
  u64 nd_sb_checksum(struct nd_gen_sb *nd_gen_sb)
  {
  	u64 sum;
  	__le64 sum_save;
  
  	BUILD_BUG_ON(sizeof(struct btt_sb) != SZ_4K);
  	BUILD_BUG_ON(sizeof(struct nd_pfn_sb) != SZ_4K);
  	BUILD_BUG_ON(sizeof(struct nd_gen_sb) != SZ_4K);
  
  	sum_save = nd_gen_sb->checksum;
  	nd_gen_sb->checksum = 0;
  	sum = nd_fletcher64(nd_gen_sb, sizeof(*nd_gen_sb), 1);
  	nd_gen_sb->checksum = sum_save;
  	return sum;
  }
  EXPORT_SYMBOL(nd_sb_checksum);

  
  static int nsio_rw_bytes(struct nd_namespace_common *ndns,

  		resource_size_t offset, void *buf, size_t size, int rw,
  		unsigned long flags)

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

  	unsigned int sz_align = ALIGN(size + (offset & (512 - 1)), 512);
  	sector_t sector = offset >> 9;
  	int rc = 0;
  
  	if (unlikely(!size))
  		return 0;

  
  	if (unlikely(offset + size > nsio->size)) {
  		dev_WARN_ONCE(&ndns->dev, 1, "request out of range
  ");
  		return -EFAULT;
  	}
  
  	if (rw == READ) {

  		if (unlikely(is_bad_pmem(&nsio->bb, sector, sz_align)))

  			return -EIO;

  		return memcpy_mcsafe(buf, nsio->addr + offset, size);

  	}
  
  	if (unlikely(is_bad_pmem(&nsio->bb, sector, sz_align))) {

  		if (IS_ALIGNED(offset, 512) && IS_ALIGNED(size, 512)

  				&& !(flags & NVDIMM_IO_ATOMIC)) {

  			long cleared;

  			might_sleep();

  			cleared = nvdimm_clear_poison(&ndns->dev,
  					nsio->res.start + offset, size);

  			if (cleared < size)

  				rc = -EIO;

  			if (cleared > 0 && cleared / 512) {
  				cleared /= 512;
  				badblocks_clear(&nsio->bb, sector, cleared);

  			}

  			arch_invalidate_pmem(nsio->addr + offset, size);

  		} else
  			rc = -EIO;

  	}

  	memcpy_flushcache(nsio->addr + offset, buf, size);

  	nvdimm_flush(to_nd_region(ndns->dev.parent));

  	return rc;

  }
  
  int devm_nsio_enable(struct device *dev, struct nd_namespace_io *nsio)
  {
  	struct resource *res = &nsio->res;
  	struct nd_namespace_common *ndns = &nsio->common;
  
  	nsio->size = resource_size(res);
  	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;
  	}
  
  	ndns->rw_bytes = nsio_rw_bytes;
  	if (devm_init_badblocks(dev, &nsio->bb))
  		return -ENOMEM;
  	nvdimm_badblocks_populate(to_nd_region(ndns->dev.parent), &nsio->bb,
  			&nsio->res);
  
  	nsio->addr = devm_memremap(dev, res->start, resource_size(res),
  			ARCH_MEMREMAP_PMEM);

  
  	return PTR_ERR_OR_ZERO(nsio->addr);

  }
  EXPORT_SYMBOL_GPL(devm_nsio_enable);
  
  void devm_nsio_disable(struct device *dev, struct nd_namespace_io *nsio)
  {
  	struct resource *res = &nsio->res;
  
  	devm_memunmap(dev, nsio->addr);
  	devm_exit_badblocks(dev, &nsio->bb);
  	devm_release_mem_region(dev, res->start, resource_size(res));
  }
  EXPORT_SYMBOL_GPL(devm_nsio_disable);