/*
   * 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/blkdev.h>
  #include <linux/device.h>
  #include <linux/genhd.h>
  #include <linux/sizes.h>
  #include <linux/slab.h>
  #include <linux/fs.h>
  #include <linux/mm.h>
  #include "nd-core.h"
  #include "pfn.h"
  #include "nd.h"
  
  static void nd_pfn_release(struct device *dev)
  {
  	struct nd_region *nd_region = to_nd_region(dev->parent);
  	struct nd_pfn *nd_pfn = to_nd_pfn(dev);
  
  	dev_dbg(dev, "%s
  ", __func__);
  	nd_detach_ndns(&nd_pfn->dev, &nd_pfn->ndns);
  	ida_simple_remove(&nd_region->pfn_ida, nd_pfn->id);
  	kfree(nd_pfn->uuid);
  	kfree(nd_pfn);
  }
  
  static struct device_type nd_pfn_device_type = {
  	.name = "nd_pfn",
  	.release = nd_pfn_release,
  };
  
  bool is_nd_pfn(struct device *dev)
  {
  	return dev ? dev->type == &nd_pfn_device_type : false;
  }
  EXPORT_SYMBOL(is_nd_pfn);
  
  struct nd_pfn *to_nd_pfn(struct device *dev)
  {
  	struct nd_pfn *nd_pfn = container_of(dev, struct nd_pfn, dev);
  
  	WARN_ON(!is_nd_pfn(dev));
  	return nd_pfn;
  }
  EXPORT_SYMBOL(to_nd_pfn);
  
  static ssize_t mode_show(struct device *dev,
  		struct device_attribute *attr, char *buf)
  {
  	struct nd_pfn *nd_pfn = to_nd_pfn(dev);
  
  	switch (nd_pfn->mode) {
  	case PFN_MODE_RAM:
  		return sprintf(buf, "ram
  ");
  	case PFN_MODE_PMEM:
  		return sprintf(buf, "pmem
  ");
  	default:
  		return sprintf(buf, "none
  ");
  	}
  }
  
  static ssize_t mode_store(struct device *dev,
  		struct device_attribute *attr, const char *buf, size_t len)
  {
  	struct nd_pfn *nd_pfn = to_nd_pfn(dev);
  	ssize_t rc = 0;
  
  	device_lock(dev);
  	nvdimm_bus_lock(dev);
  	if (dev->driver)
  		rc = -EBUSY;
  	else {
  		size_t n = len - 1;
  
  		if (strncmp(buf, "pmem
  ", n) == 0
  				|| strncmp(buf, "pmem", n) == 0) {
  			/* TODO: allocate from PMEM support */
  			rc = -ENOTTY;
  		} else if (strncmp(buf, "ram
  ", n) == 0
  				|| strncmp(buf, "ram", n) == 0)
  			nd_pfn->mode = PFN_MODE_RAM;
  		else if (strncmp(buf, "none
  ", n) == 0
  				|| strncmp(buf, "none", n) == 0)
  			nd_pfn->mode = PFN_MODE_NONE;
  		else
  			rc = -EINVAL;
  	}
  	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
  			rc, buf, buf[len - 1] == '
  ' ? "" : "
  ");
  	nvdimm_bus_unlock(dev);
  	device_unlock(dev);
  
  	return rc ? rc : len;
  }
  static DEVICE_ATTR_RW(mode);
  
  static ssize_t uuid_show(struct device *dev,
  		struct device_attribute *attr, char *buf)
  {
  	struct nd_pfn *nd_pfn = to_nd_pfn(dev);
  
  	if (nd_pfn->uuid)
  		return sprintf(buf, "%pUb
  ", nd_pfn->uuid);
  	return sprintf(buf, "
  ");
  }
  
  static ssize_t uuid_store(struct device *dev,
  		struct device_attribute *attr, const char *buf, size_t len)
  {
  	struct nd_pfn *nd_pfn = to_nd_pfn(dev);
  	ssize_t rc;
  
  	device_lock(dev);
  	rc = nd_uuid_store(dev, &nd_pfn->uuid, buf, len);
  	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
  			rc, buf, buf[len - 1] == '
  ' ? "" : "
  ");
  	device_unlock(dev);
  
  	return rc ? rc : len;
  }
  static DEVICE_ATTR_RW(uuid);
  
  static ssize_t namespace_show(struct device *dev,
  		struct device_attribute *attr, char *buf)
  {
  	struct nd_pfn *nd_pfn = to_nd_pfn(dev);
  	ssize_t rc;
  
  	nvdimm_bus_lock(dev);
  	rc = sprintf(buf, "%s
  ", nd_pfn->ndns
  			? dev_name(&nd_pfn->ndns->dev) : "");
  	nvdimm_bus_unlock(dev);
  	return rc;
  }
  
  static ssize_t namespace_store(struct device *dev,
  		struct device_attribute *attr, const char *buf, size_t len)
  {
  	struct nd_pfn *nd_pfn = to_nd_pfn(dev);
  	ssize_t rc;
  
  	device_lock(dev);
  	nvdimm_bus_lock(dev);
  	rc = nd_namespace_store(dev, &nd_pfn->ndns, buf, len);
  	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
  			rc, buf, buf[len - 1] == '
  ' ? "" : "
  ");
  	nvdimm_bus_unlock(dev);
  	device_unlock(dev);
  
  	return rc;
  }
  static DEVICE_ATTR_RW(namespace);
  
  static struct attribute *nd_pfn_attributes[] = {
  	&dev_attr_mode.attr,
  	&dev_attr_namespace.attr,
  	&dev_attr_uuid.attr,
  	NULL,
  };
  
  static struct attribute_group nd_pfn_attribute_group = {
  	.attrs = nd_pfn_attributes,
  };
  
  static const struct attribute_group *nd_pfn_attribute_groups[] = {
  	&nd_pfn_attribute_group,
  	&nd_device_attribute_group,
  	&nd_numa_attribute_group,
  	NULL,
  };
  
  static struct device *__nd_pfn_create(struct nd_region *nd_region,
  		u8 *uuid, enum nd_pfn_mode mode,
  		struct nd_namespace_common *ndns)
  {
  	struct nd_pfn *nd_pfn;
  	struct device *dev;
  
  	/* we can only create pages for contiguous ranged of pmem */
  	if (!is_nd_pmem(&nd_region->dev))
  		return NULL;
  
  	nd_pfn = kzalloc(sizeof(*nd_pfn), GFP_KERNEL);
  	if (!nd_pfn)
  		return NULL;
  
  	nd_pfn->id = ida_simple_get(&nd_region->pfn_ida, 0, 0, GFP_KERNEL);
  	if (nd_pfn->id < 0) {
  		kfree(nd_pfn);
  		return NULL;
  	}
  
  	nd_pfn->mode = mode;
  	if (uuid)
  		uuid = kmemdup(uuid, 16, GFP_KERNEL);
  	nd_pfn->uuid = uuid;
  	dev = &nd_pfn->dev;
  	dev_set_name(dev, "pfn%d.%d", nd_region->id, nd_pfn->id);
  	dev->parent = &nd_region->dev;
  	dev->type = &nd_pfn_device_type;
  	dev->groups = nd_pfn_attribute_groups;
  	device_initialize(&nd_pfn->dev);
  	if (ndns && !__nd_attach_ndns(&nd_pfn->dev, ndns, &nd_pfn->ndns)) {
  		dev_dbg(&ndns->dev, "%s failed, already claimed by %s
  ",
  				__func__, dev_name(ndns->claim));
  		put_device(dev);
  		return NULL;
  	}
  	return dev;
  }
  
  struct device *nd_pfn_create(struct nd_region *nd_region)
  {
  	struct device *dev = __nd_pfn_create(nd_region, NULL, PFN_MODE_NONE,
  			NULL);
  
  	if (dev)
  		__nd_device_register(dev);
  	return dev;
  }
  
  int nd_pfn_validate(struct nd_pfn *nd_pfn)
  {
  	struct nd_namespace_common *ndns = nd_pfn->ndns;
  	struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
  	struct nd_namespace_io *nsio;
  	u64 checksum, offset;
  
  	if (!pfn_sb || !ndns)
  		return -ENODEV;
  
  	if (!is_nd_pmem(nd_pfn->dev.parent))
  		return -ENODEV;
  
  	/* section alignment for simple hotplug */
  	if (nvdimm_namespace_capacity(ndns) < ND_PFN_ALIGN)
  		return -ENODEV;
  
  	if (nvdimm_read_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb)))
  		return -ENXIO;
  
  	if (memcmp(pfn_sb->signature, PFN_SIG, PFN_SIG_LEN) != 0)
  		return -ENODEV;
  
  	checksum = le64_to_cpu(pfn_sb->checksum);
  	pfn_sb->checksum = 0;
  	if (checksum != nd_sb_checksum((struct nd_gen_sb *) pfn_sb))
  		return -ENODEV;
  	pfn_sb->checksum = cpu_to_le64(checksum);
  
  	switch (le32_to_cpu(pfn_sb->mode)) {
  	case PFN_MODE_RAM:
  		break;
  	case PFN_MODE_PMEM:
  		/* TODO: allocate from PMEM support */
  		return -ENOTTY;
  	default:
  		return -ENXIO;
  	}
  
  	if (!nd_pfn->uuid) {
  		/* from probe we allocate */
  		nd_pfn->uuid = kmemdup(pfn_sb->uuid, 16, GFP_KERNEL);
  		if (!nd_pfn->uuid)
  			return -ENOMEM;
  	} else {
  		/* from init we validate */
  		if (memcmp(nd_pfn->uuid, pfn_sb->uuid, 16) != 0)
  			return -ENODEV;
  	}
  
  	/*
  	 * These warnings are verbose because they can only trigger in
  	 * the case where the physical address alignment of the
  	 * namespace has changed since the pfn superblock was
  	 * established.
  	 */
  	offset = le64_to_cpu(pfn_sb->dataoff);
  	nsio = to_nd_namespace_io(&ndns->dev);
  	if (nsio->res.start & ND_PFN_MASK) {
  		dev_err(&nd_pfn->dev,
  				"init failed: %s not section aligned
  ",
  				dev_name(&ndns->dev));
  		return -EBUSY;
  	} else if (offset >= resource_size(&nsio->res)) {
  		dev_err(&nd_pfn->dev, "pfn array size exceeds capacity of %s
  ",
  				dev_name(&ndns->dev));
  		return -EBUSY;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL(nd_pfn_validate);
  
  int nd_pfn_probe(struct nd_namespace_common *ndns, void *drvdata)
  {
  	int rc;
  	struct device *dev;
  	struct nd_pfn *nd_pfn;
  	struct nd_pfn_sb *pfn_sb;
  	struct nd_region *nd_region = to_nd_region(ndns->dev.parent);
  
  	if (ndns->force_raw)
  		return -ENODEV;
  
  	nvdimm_bus_lock(&ndns->dev);
  	dev = __nd_pfn_create(nd_region, NULL, PFN_MODE_NONE, ndns);
  	nvdimm_bus_unlock(&ndns->dev);
  	if (!dev)
  		return -ENOMEM;
  	dev_set_drvdata(dev, drvdata);
  	pfn_sb = kzalloc(sizeof(*pfn_sb), GFP_KERNEL);
  	nd_pfn = to_nd_pfn(dev);
  	nd_pfn->pfn_sb = pfn_sb;
  	rc = nd_pfn_validate(nd_pfn);
  	nd_pfn->pfn_sb = NULL;
  	kfree(pfn_sb);
  	dev_dbg(&ndns->dev, "%s: pfn: %s
  ", __func__,
  			rc == 0 ? dev_name(dev) : "<none>");
  	if (rc < 0) {
  		__nd_detach_ndns(dev, &nd_pfn->ndns);
  		put_device(dev);
  	} else
  		__nd_device_register(&nd_pfn->dev);
  
  	return rc;
  }
  EXPORT_SYMBOL(nd_pfn_probe);