/*
 * 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/list_sort.h>
#include <linux/libnvdimm.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/ndctl.h>
#include <linux/delay.h>
#include <linux/list.h>
#include <linux/acpi.h>
#include <linux/sort.h>
#include <linux/pmem.h>
#include <linux/io.h>
#include <asm/cacheflush.h>
#include "nfit.h"

/*
 * For readq() and writeq() on 32-bit builds, the hi-lo, lo-hi order is
 * irrelevant.
 */
#include <linux/io-64-nonatomic-hi-lo.h>

static bool force_enable_dimms;
module_param(force_enable_dimms, bool, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(force_enable_dimms, "Ignore _STA (ACPI DIMM device) status");

struct nfit_table_prev {
	struct list_head spas;
	struct list_head memdevs;
	struct list_head dcrs;
	struct list_head bdws;
	struct list_head idts;
	struct list_head flushes;
};

static u8 nfit_uuid[NFIT_UUID_MAX][16];

const u8 *to_nfit_uuid(enum nfit_uuids id)
{
	return nfit_uuid[id];
}
EXPORT_SYMBOL(to_nfit_uuid);

static struct acpi_nfit_desc *to_acpi_nfit_desc(
		struct nvdimm_bus_descriptor *nd_desc)
{
	return container_of(nd_desc, struct acpi_nfit_desc, nd_desc);
}

static struct acpi_device *to_acpi_dev(struct acpi_nfit_desc *acpi_desc)
{
	struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc;

	/*
	 * If provider == 'ACPI.NFIT' we can assume 'dev' is a struct
	 * acpi_device.
	 */
	if (!nd_desc->provider_name
			|| strcmp(nd_desc->provider_name, "ACPI.NFIT") != 0)
		return NULL;

	return to_acpi_device(acpi_desc->dev);
}

static int xlat_status(void *buf, unsigned int cmd)
{
	struct nd_cmd_ars_status *ars_status;
	struct nd_cmd_ars_start *ars_start;
	struct nd_cmd_ars_cap *ars_cap;
	u16 flags;

	switch (cmd) {
	case ND_CMD_ARS_CAP:
		ars_cap = buf;
		if ((ars_cap->status & 0xffff) == NFIT_ARS_CAP_NONE)
			return -ENOTTY;

		/* Command failed */
		if (ars_cap->status & 0xffff)
			return -EIO;

		/* No supported scan types for this range */
		flags = ND_ARS_PERSISTENT | ND_ARS_VOLATILE;
		if ((ars_cap->status >> 16 & flags) == 0)
			return -ENOTTY;
		break;
	case ND_CMD_ARS_START:
		ars_start = buf;
		/* ARS is in progress */
		if ((ars_start->status & 0xffff) == NFIT_ARS_START_BUSY)
			return -EBUSY;

		/* Command failed */
		if (ars_start->status & 0xffff)
			return -EIO;
		break;
	case ND_CMD_ARS_STATUS:
		ars_status = buf;
		/* Command failed */
		if (ars_status->status & 0xffff)
			return -EIO;
		/* Check extended status (Upper two bytes) */
		if (ars_status->status == NFIT_ARS_STATUS_DONE)
			return 0;

		/* ARS is in progress */
		if (ars_status->status == NFIT_ARS_STATUS_BUSY)
			return -EBUSY;

		/* No ARS performed for the current boot */
		if (ars_status->status == NFIT_ARS_STATUS_NONE)
			return -EAGAIN;

		/*
		 * ARS interrupted, either we overflowed or some other
		 * agent wants the scan to stop.  If we didn't overflow
		 * then just continue with the returned results.
		 */
		if (ars_status->status == NFIT_ARS_STATUS_INTR) {
			if (ars_status->flags & NFIT_ARS_F_OVERFLOW)
				return -ENOSPC;
			return 0;
		}

		/* Unknown status */
		if (ars_status->status >> 16)
			return -EIO;
		break;
	default:
		break;
	}

	return 0;
}

static int acpi_nfit_ctl(struct nvdimm_bus_descriptor *nd_desc,
		struct nvdimm *nvdimm, unsigned int cmd, void *buf,
		unsigned int buf_len, int *cmd_rc)
{
	struct acpi_nfit_desc *acpi_desc = to_acpi_nfit_desc(nd_desc);
	const struct nd_cmd_desc *desc = NULL;
	union acpi_object in_obj, in_buf, *out_obj;
	struct device *dev = acpi_desc->dev;
	const char *cmd_name, *dimm_name;
	unsigned long dsm_mask;
	acpi_handle handle;
	const u8 *uuid;
	u32 offset;
	int rc, i;

	if (nvdimm) {
		struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm);
		struct acpi_device *adev = nfit_mem->adev;

		if (!adev)
			return -ENOTTY;
		dimm_name = nvdimm_name(nvdimm);
		cmd_name = nvdimm_cmd_name(cmd);
		dsm_mask = nfit_mem->dsm_mask;
		desc = nd_cmd_dimm_desc(cmd);
		uuid = to_nfit_uuid(NFIT_DEV_DIMM);
		handle = adev->handle;
	} else {
		struct acpi_device *adev = to_acpi_dev(acpi_desc);

		cmd_name = nvdimm_bus_cmd_name(cmd);
		dsm_mask = nd_desc->dsm_mask;
		desc = nd_cmd_bus_desc(cmd);
		uuid = to_nfit_uuid(NFIT_DEV_BUS);
		handle = adev->handle;
		dimm_name = "bus";
	}

	if (!desc || (cmd && (desc->out_num + desc->in_num == 0)))
		return -ENOTTY;

	if (!test_bit(cmd, &dsm_mask))
		return -ENOTTY;

	in_obj.type = ACPI_TYPE_PACKAGE;
	in_obj.package.count = 1;
	in_obj.package.elements = &in_buf;
	in_buf.type = ACPI_TYPE_BUFFER;
	in_buf.buffer.pointer = buf;
	in_buf.buffer.length = 0;

	/* libnvdimm has already validated the input envelope */
	for (i = 0; i < desc->in_num; i++)
		in_buf.buffer.length += nd_cmd_in_size(nvdimm, cmd, desc,
				i, buf);

	if (IS_ENABLED(CONFIG_ACPI_NFIT_DEBUG)) {
		dev_dbg(dev, "%s:%s cmd: %s input length: %d\n", __func__,
				dimm_name, cmd_name, in_buf.buffer.length);
		print_hex_dump_debug(cmd_name, DUMP_PREFIX_OFFSET, 4,
				4, in_buf.buffer.pointer, min_t(u32, 128,
					in_buf.buffer.length), true);
	}

	out_obj = acpi_evaluate_dsm(handle, uuid, 1, cmd, &in_obj);
	if (!out_obj) {
		dev_dbg(dev, "%s:%s _DSM failed cmd: %s\n", __func__, dimm_name,
				cmd_name);
		return -EINVAL;
	}

	if (out_obj->package.type != ACPI_TYPE_BUFFER) {
		dev_dbg(dev, "%s:%s unexpected output object type cmd: %s type: %d\n",
				__func__, dimm_name, cmd_name, out_obj->type);
		rc = -EINVAL;
		goto out;
	}

	if (IS_ENABLED(CONFIG_ACPI_NFIT_DEBUG)) {
		dev_dbg(dev, "%s:%s cmd: %s output length: %d\n", __func__,
				dimm_name, cmd_name, out_obj->buffer.length);
		print_hex_dump_debug(cmd_name, DUMP_PREFIX_OFFSET, 4,
				4, out_obj->buffer.pointer, min_t(u32, 128,
					out_obj->buffer.length), true);
	}

	for (i = 0, offset = 0; i < desc->out_num; i++) {
		u32 out_size = nd_cmd_out_size(nvdimm, cmd, desc, i, buf,
				(u32 *) out_obj->buffer.pointer);

		if (offset + out_size > out_obj->buffer.length) {
			dev_dbg(dev, "%s:%s output object underflow cmd: %s field: %d\n",
					__func__, dimm_name, cmd_name, i);
			break;
		}

		if (in_buf.buffer.length + offset + out_size > buf_len) {
			dev_dbg(dev, "%s:%s output overrun cmd: %s field: %d\n",
					__func__, dimm_name, cmd_name, i);
			rc = -ENXIO;
			goto out;
		}
		memcpy(buf + in_buf.buffer.length + offset,
				out_obj->buffer.pointer + offset, out_size);
		offset += out_size;
	}
	if (offset + in_buf.buffer.length < buf_len) {
		if (i >= 1) {
			/*
			 * status valid, return the number of bytes left
			 * unfilled in the output buffer
			 */
			rc = buf_len - offset - in_buf.buffer.length;
			if (cmd_rc)
				*cmd_rc = xlat_status(buf, cmd);
		} else {
			dev_err(dev, "%s:%s underrun cmd: %s buf_len: %d out_len: %d\n",
					__func__, dimm_name, cmd_name, buf_len,
					offset);
			rc = -ENXIO;
		}
	} else
		rc = 0;

 out:
	ACPI_FREE(out_obj);

	return rc;
}

static const char *spa_type_name(u16 type)
{
	static const char *to_name[] = {
		[NFIT_SPA_VOLATILE] = "volatile",
		[NFIT_SPA_PM] = "pmem",
		[NFIT_SPA_DCR] = "dimm-control-region",
		[NFIT_SPA_BDW] = "block-data-window",
		[NFIT_SPA_VDISK] = "volatile-disk",
		[NFIT_SPA_VCD] = "volatile-cd",
		[NFIT_SPA_PDISK] = "persistent-disk",
		[NFIT_SPA_PCD] = "persistent-cd",

	};

	if (type > NFIT_SPA_PCD)
		return "unknown";

	return to_name[type];
}

static int nfit_spa_type(struct acpi_nfit_system_address *spa)
{
	int i;

	for (i = 0; i < NFIT_UUID_MAX; i++)
		if (memcmp(to_nfit_uuid(i), spa->range_guid, 16) == 0)
			return i;
	return -1;
}

static bool add_spa(struct acpi_nfit_desc *acpi_desc,
		struct nfit_table_prev *prev,
		struct acpi_nfit_system_address *spa)
{
	size_t length = min_t(size_t, sizeof(*spa), spa->header.length);
	struct device *dev = acpi_desc->dev;
	struct nfit_spa *nfit_spa;

	list_for_each_entry(nfit_spa, &prev->spas, list) {
		if (memcmp(nfit_spa->spa, spa, length) == 0) {
			list_move_tail(&nfit_spa->list, &acpi_desc->spas);
			return true;
		}
	}

	nfit_spa = devm_kzalloc(dev, sizeof(*nfit_spa), GFP_KERNEL);
	if (!nfit_spa)
		return false;
	INIT_LIST_HEAD(&nfit_spa->list);
	nfit_spa->spa = spa;
	list_add_tail(&nfit_spa->list, &acpi_desc->spas);
	dev_dbg(dev, "%s: spa index: %d type: %s\n", __func__,
			spa->range_index,
			spa_type_name(nfit_spa_type(spa)));
	return true;
}

static bool add_memdev(struct acpi_nfit_desc *acpi_desc,
		struct nfit_table_prev *prev,
		struct acpi_nfit_memory_map *memdev)
{
	size_t length = min_t(size_t, sizeof(*memdev), memdev->header.length);
	struct device *dev = acpi_desc->dev;
	struct nfit_memdev *nfit_memdev;

	list_for_each_entry(nfit_memdev, &prev->memdevs, list)
		if (memcmp(nfit_memdev->memdev, memdev, length) == 0) {
			list_move_tail(&nfit_memdev->list, &acpi_desc->memdevs);
			return true;
		}

	nfit_memdev = devm_kzalloc(dev, sizeof(*nfit_memdev), GFP_KERNEL);
	if (!nfit_memdev)
		return false;
	INIT_LIST_HEAD(&nfit_memdev->list);
	nfit_memdev->memdev = memdev;
	list_add_tail(&nfit_memdev->list, &acpi_desc->memdevs);
	dev_dbg(dev, "%s: memdev handle: %#x spa: %d dcr: %d\n",
			__func__, memdev->device_handle, memdev->range_index,
			memdev->region_index);
	return true;
}

static bool add_dcr(struct acpi_nfit_desc *acpi_desc,
		struct nfit_table_prev *prev,
		struct acpi_nfit_control_region *dcr)
{
	size_t length = min_t(size_t, sizeof(*dcr), dcr->header.length);
	struct device *dev = acpi_desc->dev;
	struct nfit_dcr *nfit_dcr;

	list_for_each_entry(nfit_dcr, &prev->dcrs, list)
		if (memcmp(nfit_dcr->dcr, dcr, length) == 0) {
			list_move_tail(&nfit_dcr->list, &acpi_desc->dcrs);
			return true;
		}

	nfit_dcr = devm_kzalloc(dev, sizeof(*nfit_dcr), GFP_KERNEL);
	if (!nfit_dcr)
		return false;
	INIT_LIST_HEAD(&nfit_dcr->list);
	nfit_dcr->dcr = dcr;
	list_add_tail(&nfit_dcr->list, &acpi_desc->dcrs);
	dev_dbg(dev, "%s: dcr index: %d windows: %d\n", __func__,
			dcr->region_index, dcr->windows);
	return true;
}

static bool add_bdw(struct acpi_nfit_desc *acpi_desc,
		struct nfit_table_prev *prev,
		struct acpi_nfit_data_region *bdw)
{
	size_t length = min_t(size_t, sizeof(*bdw), bdw->header.length);
	struct device *dev = acpi_desc->dev;
	struct nfit_bdw *nfit_bdw;

	list_for_each_entry(nfit_bdw, &prev->bdws, list)
		if (memcmp(nfit_bdw->bdw, bdw, length) == 0) {
			list_move_tail(&nfit_bdw->list, &acpi_desc->bdws);
			return true;
		}

	nfit_bdw = devm_kzalloc(dev, sizeof(*nfit_bdw), GFP_KERNEL);
	if (!nfit_bdw)
		return false;
	INIT_LIST_HEAD(&nfit_bdw->list);
	nfit_bdw->bdw = bdw;
	list_add_tail(&nfit_bdw->list, &acpi_desc->bdws);
	dev_dbg(dev, "%s: bdw dcr: %d windows: %d\n", __func__,
			bdw->region_index, bdw->windows);
	return true;
}

static bool add_idt(struct acpi_nfit_desc *acpi_desc,
		struct nfit_table_prev *prev,
		struct acpi_nfit_interleave *idt)
{
	size_t length = min_t(size_t, sizeof(*idt), idt->header.length);
	struct device *dev = acpi_desc->dev;
	struct nfit_idt *nfit_idt;

	list_for_each_entry(nfit_idt, &prev->idts, list)
		if (memcmp(nfit_idt->idt, idt, length) == 0) {
			list_move_tail(&nfit_idt->list, &acpi_desc->idts);
			return true;
		}

	nfit_idt = devm_kzalloc(dev, sizeof(*nfit_idt), GFP_KERNEL);
	if (!nfit_idt)
		return false;
	INIT_LIST_HEAD(&nfit_idt->list);
	nfit_idt->idt = idt;
	list_add_tail(&nfit_idt->list, &acpi_desc->idts);
	dev_dbg(dev, "%s: idt index: %d num_lines: %d\n", __func__,
			idt->interleave_index, idt->line_count);
	return true;
}

static bool add_flush(struct acpi_nfit_desc *acpi_desc,
		struct nfit_table_prev *prev,
		struct acpi_nfit_flush_address *flush)
{
	size_t length = min_t(size_t, sizeof(*flush), flush->header.length);
	struct device *dev = acpi_desc->dev;
	struct nfit_flush *nfit_flush;

	list_for_each_entry(nfit_flush, &prev->flushes, list)
		if (memcmp(nfit_flush->flush, flush, length) == 0) {
			list_move_tail(&nfit_flush->list, &acpi_desc->flushes);
			return true;
		}

	nfit_flush = devm_kzalloc(dev, sizeof(*nfit_flush), GFP_KERNEL);
	if (!nfit_flush)
		return false;
	INIT_LIST_HEAD(&nfit_flush->list);
	nfit_flush->flush = flush;
	list_add_tail(&nfit_flush->list, &acpi_desc->flushes);
	dev_dbg(dev, "%s: nfit_flush handle: %d hint_count: %d\n", __func__,
			flush->device_handle, flush->hint_count);
	return true;
}

static void *add_table(struct acpi_nfit_desc *acpi_desc,
		struct nfit_table_prev *prev, void *table, const void *end)
{
	struct device *dev = acpi_desc->dev;
	struct acpi_nfit_header *hdr;
	void *err = ERR_PTR(-ENOMEM);

	if (table >= end)
		return NULL;

	hdr = table;
	if (!hdr->length) {
		dev_warn(dev, "found a zero length table '%d' parsing nfit\n",
			hdr->type);
		return NULL;
	}

	switch (hdr->type) {
	case ACPI_NFIT_TYPE_SYSTEM_ADDRESS:
		if (!add_spa(acpi_desc, prev, table))
			return err;
		break;
	case ACPI_NFIT_TYPE_MEMORY_MAP:
		if (!add_memdev(acpi_desc, prev, table))
			return err;
		break;
	case ACPI_NFIT_TYPE_CONTROL_REGION:
		if (!add_dcr(acpi_desc, prev, table))
			return err;
		break;
	case ACPI_NFIT_TYPE_DATA_REGION:
		if (!add_bdw(acpi_desc, prev, table))
			return err;
		break;
	case ACPI_NFIT_TYPE_INTERLEAVE:
		if (!add_idt(acpi_desc, prev, table))
			return err;
		break;
	case ACPI_NFIT_TYPE_FLUSH_ADDRESS:
		if (!add_flush(acpi_desc, prev, table))
			return err;
		break;
	case ACPI_NFIT_TYPE_SMBIOS:
		dev_dbg(dev, "%s: smbios\n", __func__);
		break;
	default:
		dev_err(dev, "unknown table '%d' parsing nfit\n", hdr->type);
		break;
	}

	return table + hdr->length;
}

static void nfit_mem_find_spa_bdw(struct acpi_nfit_desc *acpi_desc,
		struct nfit_mem *nfit_mem)
{
	u32 device_handle = __to_nfit_memdev(nfit_mem)->device_handle;
	u16 dcr = nfit_mem->dcr->region_index;
	struct nfit_spa *nfit_spa;

	list_for_each_entry(nfit_spa, &acpi_desc->spas, list) {
		u16 range_index = nfit_spa->spa->range_index;
		int type = nfit_spa_type(nfit_spa->spa);
		struct nfit_memdev *nfit_memdev;

		if (type != NFIT_SPA_BDW)
			continue;

		list_for_each_entry(nfit_memdev, &acpi_desc->memdevs, list) {
			if (nfit_memdev->memdev->range_index != range_index)
				continue;
			if (nfit_memdev->memdev->device_handle != device_handle)
				continue;
			if (nfit_memdev->memdev->region_index != dcr)
				continue;

			nfit_mem->spa_bdw = nfit_spa->spa;
			return;
		}
	}

	dev_dbg(acpi_desc->dev, "SPA-BDW not found for SPA-DCR %d\n",
			nfit_mem->spa_dcr->range_index);
	nfit_mem->bdw = NULL;
}

static void nfit_mem_init_bdw(struct acpi_nfit_desc *acpi_desc,
		struct nfit_mem *nfit_mem, struct acpi_nfit_system_address *spa)
{
	u16 dcr = __to_nfit_memdev(nfit_mem)->region_index;
	struct nfit_memdev *nfit_memdev;
	struct nfit_flush *nfit_flush;
	struct nfit_bdw *nfit_bdw;
	struct nfit_idt *nfit_idt;
	u16 idt_idx, range_index;

	list_for_each_entry(nfit_bdw, &acpi_desc->bdws, list) {
		if (nfit_bdw->bdw->region_index != dcr)
			continue;
		nfit_mem->bdw = nfit_bdw->bdw;
		break;
	}

	if (!nfit_mem->bdw)
		return;

	nfit_mem_find_spa_bdw(acpi_desc, nfit_mem);

	if (!nfit_mem->spa_bdw)
		return;

	range_index = nfit_mem->spa_bdw->range_index;
	list_for_each_entry(nfit_memdev, &acpi_desc->memdevs, list) {
		if (nfit_memdev->memdev->range_index != range_index ||
				nfit_memdev->memdev->region_index != dcr)
			continue;
		nfit_mem->memdev_bdw = nfit_memdev->memdev;
		idt_idx = nfit_memdev->memdev->interleave_index;
		list_for_each_entry(nfit_idt, &acpi_desc->idts, list) {
			if (nfit_idt->idt->interleave_index != idt_idx)
				continue;
			nfit_mem->idt_bdw = nfit_idt->idt;
			break;
		}

		list_for_each_entry(nfit_flush, &acpi_desc->flushes, list) {
			if (nfit_flush->flush->device_handle !=
					nfit_memdev->memdev->device_handle)
				continue;
			nfit_mem->nfit_flush = nfit_flush;
			break;
		}
		break;
	}
}

static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
		struct acpi_nfit_system_address *spa)
{
	struct nfit_mem *nfit_mem, *found;
	struct nfit_memdev *nfit_memdev;
	int type = nfit_spa_type(spa);

	switch (type) {
	case NFIT_SPA_DCR:
	case NFIT_SPA_PM:
		break;
	default:
		return 0;
	}

	list_for_each_entry(nfit_memdev, &acpi_desc->memdevs, list) {
		struct nfit_dcr *nfit_dcr;
		u32 device_handle;
		u16 dcr;

		if (nfit_memdev->memdev->range_index != spa->range_index)
			continue;
		found = NULL;
		dcr = nfit_memdev->memdev->region_index;
		device_handle = nfit_memdev->memdev->device_handle;
		list_for_each_entry(nfit_mem, &acpi_desc->dimms, list)
			if (__to_nfit_memdev(nfit_mem)->device_handle
					== device_handle) {
				found = nfit_mem;
				break;
			}

		if (found)
			nfit_mem = found;
		else {
			nfit_mem = devm_kzalloc(acpi_desc->dev,
					sizeof(*nfit_mem), GFP_KERNEL);
			if (!nfit_mem)
				return -ENOMEM;
			INIT_LIST_HEAD(&nfit_mem->list);
			list_add(&nfit_mem->list, &acpi_desc->dimms);
		}

		list_for_each_entry(nfit_dcr, &acpi_desc->dcrs, list) {
			if (nfit_dcr->dcr->region_index != dcr)
				continue;
			/*
			 * Record the control region for the dimm.  For
			 * the ACPI 6.1 case, where there are separate
			 * control regions for the pmem vs blk
			 * interfaces, be sure to record the extended
			 * blk details.
			 */
			if (!nfit_mem->dcr)
				nfit_mem->dcr = nfit_dcr->dcr;
			else if (nfit_mem->dcr->windows == 0
					&& nfit_dcr->dcr->windows)
				nfit_mem->dcr = nfit_dcr->dcr;
			break;
		}

		if (dcr && !nfit_mem->dcr) {
			dev_err(acpi_desc->dev, "SPA %d missing DCR %d\n",
					spa->range_index, dcr);
			return -ENODEV;
		}

		if (type == NFIT_SPA_DCR) {
			struct nfit_idt *nfit_idt;
			u16 idt_idx;

			/* multiple dimms may share a SPA when interleaved */
			nfit_mem->spa_dcr = spa;
			nfit_mem->memdev_dcr = nfit_memdev->memdev;
			idt_idx = nfit_memdev->memdev->interleave_index;
			list_for_each_entry(nfit_idt, &acpi_desc->idts, list) {
				if (nfit_idt->idt->interleave_index != idt_idx)
					continue;
				nfit_mem->idt_dcr = nfit_idt->idt;
				break;
			}
			nfit_mem_init_bdw(acpi_desc, nfit_mem, spa);
		} else {
			/*
			 * A single dimm may belong to multiple SPA-PM
			 * ranges, record at least one in addition to
			 * any SPA-DCR range.
			 */
			nfit_mem->memdev_pmem = nfit_memdev->memdev;
		}
	}

	return 0;
}

static int nfit_mem_cmp(void *priv, struct list_head *_a, struct list_head *_b)
{
	struct nfit_mem *a = container_of(_a, typeof(*a), list);
	struct nfit_mem *b = container_of(_b, typeof(*b), list);
	u32 handleA, handleB;

	handleA = __to_nfit_memdev(a)->device_handle;
	handleB = __to_nfit_memdev(b)->device_handle;
	if (handleA < handleB)
		return -1;
	else if (handleA > handleB)
		return 1;
	return 0;
}

static int nfit_mem_init(struct acpi_nfit_desc *acpi_desc)
{
	struct nfit_spa *nfit_spa;

	/*
	 * For each SPA-DCR or SPA-PMEM address range find its
	 * corresponding MEMDEV(s).  From each MEMDEV find the
	 * corresponding DCR.  Then, if we're operating on a SPA-DCR,
	 * try to find a SPA-BDW and a corresponding BDW that references
	 * the DCR.  Throw it all into an nfit_mem object.  Note, that
	 * BDWs are optional.
	 */
	list_for_each_entry(nfit_spa, &acpi_desc->spas, list) {
		int rc;

		rc = nfit_mem_dcr_init(acpi_desc, nfit_spa->spa);
		if (rc)
			return rc;
	}

	list_sort(NULL, &acpi_desc->dimms, nfit_mem_cmp);

	return 0;
}

static ssize_t revision_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct nvdimm_bus *nvdimm_bus = to_nvdimm_bus(dev);
	struct nvdimm_bus_descriptor *nd_desc = to_nd_desc(nvdimm_bus);
	struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);

	return sprintf(buf, "%d\n", acpi_desc->acpi_header.revision);
}
static DEVICE_ATTR_RO(revision);

static struct attribute *acpi_nfit_attributes[] = {
	&dev_attr_revision.attr,
	NULL,
};

static struct attribute_group acpi_nfit_attribute_group = {
	.name = "nfit",
	.attrs = acpi_nfit_attributes,
};

static const struct attribute_group *acpi_nfit_attribute_groups[] = {
	&nvdimm_bus_attribute_group,
	&acpi_nfit_attribute_group,
	NULL,
};

static struct acpi_nfit_memory_map *to_nfit_memdev(struct device *dev)
{
	struct nvdimm *nvdimm = to_nvdimm(dev);
	struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm);

	return __to_nfit_memdev(nfit_mem);
}

static struct acpi_nfit_control_region *to_nfit_dcr(struct device *dev)
{
	struct nvdimm *nvdimm = to_nvdimm(dev);
	struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm);

	return nfit_mem->dcr;
}

static ssize_t handle_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct acpi_nfit_memory_map *memdev = to_nfit_memdev(dev);

	return sprintf(buf, "%#x\n", memdev->device_handle);
}
static DEVICE_ATTR_RO(handle);

static ssize_t phys_id_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct acpi_nfit_memory_map *memdev = to_nfit_memdev(dev);

	return sprintf(buf, "%#x\n", memdev->physical_id);
}
static DEVICE_ATTR_RO(phys_id);

static ssize_t vendor_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct acpi_nfit_control_region *dcr = to_nfit_dcr(dev);

	return sprintf(buf, "%#x\n", dcr->vendor_id);
}
static DEVICE_ATTR_RO(vendor);

static ssize_t rev_id_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct acpi_nfit_control_region *dcr = to_nfit_dcr(dev);

	return sprintf(buf, "%#x\n", dcr->revision_id);
}
static DEVICE_ATTR_RO(rev_id);

static ssize_t device_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct acpi_nfit_control_region *dcr = to_nfit_dcr(dev);

	return sprintf(buf, "%#x\n", dcr->device_id);
}
static DEVICE_ATTR_RO(device);

static ssize_t format_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct acpi_nfit_control_region *dcr = to_nfit_dcr(dev);

	return sprintf(buf, "%#x\n", dcr->code);
}
static DEVICE_ATTR_RO(format);

static ssize_t serial_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct acpi_nfit_control_region *dcr = to_nfit_dcr(dev);

	return sprintf(buf, "%#x\n", dcr->serial_number);
}
static DEVICE_ATTR_RO(serial);

static ssize_t flags_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	u16 flags = to_nfit_memdev(dev)->flags;

	return sprintf(buf, "%s%s%s%s%s\n",
		flags & ACPI_NFIT_MEM_SAVE_FAILED ? "save_fail " : "",
		flags & ACPI_NFIT_MEM_RESTORE_FAILED ? "restore_fail " : "",
		flags & ACPI_NFIT_MEM_FLUSH_FAILED ? "flush_fail " : "",
		flags & ACPI_NFIT_MEM_NOT_ARMED ? "not_armed " : "",
		flags & ACPI_NFIT_MEM_HEALTH_OBSERVED ? "smart_event " : "");
}
static DEVICE_ATTR_RO(flags);

static struct attribute *acpi_nfit_dimm_attributes[] = {
	&dev_attr_handle.attr,
	&dev_attr_phys_id.attr,
	&dev_attr_vendor.attr,
	&dev_attr_device.attr,
	&dev_attr_format.attr,
	&dev_attr_serial.attr,
	&dev_attr_rev_id.attr,
	&dev_attr_flags.attr,
	NULL,
};

static umode_t acpi_nfit_dimm_attr_visible(struct kobject *kobj,
		struct attribute *a, int n)
{
	struct device *dev = container_of(kobj, struct device, kobj);

	if (to_nfit_dcr(dev))
		return a->mode;
	else
		return 0;
}

static struct attribute_group acpi_nfit_dimm_attribute_group = {
	.name = "nfit",
	.attrs = acpi_nfit_dimm_attributes,
	.is_visible = acpi_nfit_dimm_attr_visible,
};

static const struct attribute_group *acpi_nfit_dimm_attribute_groups[] = {
	&nvdimm_attribute_group,
	&nd_device_attribute_group,
	&acpi_nfit_dimm_attribute_group,
	NULL,
};

static struct nvdimm *acpi_nfit_dimm_by_handle(struct acpi_nfit_desc *acpi_desc,
		u32 device_handle)
{
	struct nfit_mem *nfit_mem;

	list_for_each_entry(nfit_mem, &acpi_desc->dimms, list)
		if (__to_nfit_memdev(nfit_mem)->device_handle == device_handle)
			return nfit_mem->nvdimm;

	return NULL;
}

static int acpi_nfit_add_dimm(struct acpi_nfit_desc *acpi_desc,
		struct nfit_mem *nfit_mem, u32 device_handle)
{
	struct acpi_device *adev, *adev_dimm;
	struct device *dev = acpi_desc->dev;
	const u8 *uuid = to_nfit_uuid(NFIT_DEV_DIMM);
	int i;

	nfit_mem->dsm_mask = acpi_desc->dimm_dsm_force_en;
	adev = to_acpi_dev(acpi_desc);
	if (!adev)
		return 0;

	adev_dimm = acpi_find_child_device(adev, device_handle, false);
	nfit_mem->adev = adev_dimm;
	if (!adev_dimm) {
		dev_err(dev, "no ACPI.NFIT device with _ADR %#x, disabling...\n",
				device_handle);
		return force_enable_dimms ? 0 : -ENODEV;
	}

	for (i = ND_CMD_SMART; i <= ND_CMD_VENDOR; i++)
		if (acpi_check_dsm(adev_dimm->handle, uuid, 1, 1ULL << i))
			set_bit(i, &nfit_mem->dsm_mask);

	return 0;
}

static int acpi_nfit_register_dimms(struct acpi_nfit_desc *acpi_desc)
{
	struct nfit_mem *nfit_mem;
	int dimm_count = 0;

	list_for_each_entry(nfit_mem, &acpi_desc->dimms, list) {
		struct nvdimm *nvdimm;
		unsigned long flags = 0;
		u32 device_handle;
		u16 mem_flags;
		int rc;

		device_handle = __to_nfit_memdev(nfit_mem)->device_handle;
		nvdimm = acpi_nfit_dimm_by_handle(acpi_desc, device_handle);
		if (nvdimm) {
			dimm_count++;
			continue;
		}

		if (nfit_mem->bdw && nfit_mem->memdev_pmem)
			flags |= NDD_ALIASING;

		mem_flags = __to_nfit_memdev(nfit_mem)->flags;
		if (mem_flags & ACPI_NFIT_MEM_NOT_ARMED)
			flags |= NDD_UNARMED;

		rc = acpi_nfit_add_dimm(acpi_desc, nfit_mem, device_handle);
		if (rc)
			continue;

		nvdimm = nvdimm_create(acpi_desc->nvdimm_bus, nfit_mem,
				acpi_nfit_dimm_attribute_groups,
				flags, &nfit_mem->dsm_mask);
		if (!nvdimm)
			return -ENOMEM;

		nfit_mem->nvdimm = nvdimm;
		dimm_count++;

		if ((mem_flags & ACPI_NFIT_MEM_FAILED_MASK) == 0)
			continue;

		dev_info(acpi_desc->dev, "%s flags:%s%s%s%s\n",
				nvdimm_name(nvdimm),
		  mem_flags & ACPI_NFIT_MEM_SAVE_FAILED ? " save_fail" : "",
		  mem_flags & ACPI_NFIT_MEM_RESTORE_FAILED ? " restore_fail":"",
		  mem_flags & ACPI_NFIT_MEM_FLUSH_FAILED ? " flush_fail" : "",
		  mem_flags & ACPI_NFIT_MEM_NOT_ARMED ? " not_armed" : "");

	}

	return nvdimm_bus_check_dimm_count(acpi_desc->nvdimm_bus, dimm_count);
}

static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc)
{
	struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc;
	const u8 *uuid = to_nfit_uuid(NFIT_DEV_BUS);
	struct acpi_device *adev;
	int i;

	nd_desc->dsm_mask = acpi_desc->bus_dsm_force_en;
	adev = to_acpi_dev(acpi_desc);
	if (!adev)
		return;

	for (i = ND_CMD_ARS_CAP; i <= ND_CMD_ARS_STATUS; i++)
		if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i))
			set_bit(i, &nd_desc->dsm_mask);
}

static ssize_t range_index_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct nd_region *nd_region = to_nd_region(dev);
	struct nfit_spa *nfit_spa = nd_region_provider_data(nd_region);

	return sprintf(buf, "%d\n", nfit_spa->spa->range_index);
}
static DEVICE_ATTR_RO(range_index);

static struct attribute *acpi_nfit_region_attributes[] = {
	&dev_attr_range_index.attr,
	NULL,
};

static struct attribute_group acpi_nfit_region_attribute_group = {
	.name = "nfit",
	.attrs = acpi_nfit_region_attributes,
};

static const struct attribute_group *acpi_nfit_region_attribute_groups[] = {
	&nd_region_attribute_group,
	&nd_mapping_attribute_group,
	&nd_device_attribute_group,
	&nd_numa_attribute_group,
	&acpi_nfit_region_attribute_group,
	NULL,
};

/* enough info to uniquely specify an interleave set */
struct nfit_set_info {
	struct nfit_set_info_map {
		u64 region_offset;
		u32 serial_number;
		u32 pad;
	} mapping[0];
};

static size_t sizeof_nfit_set_info(int num_mappings)
{
	return sizeof(struct nfit_set_info)
		+ num_mappings * sizeof(struct nfit_set_info_map);
}

static int cmp_map(const void *m0, const void *m1)
{
	const struct nfit_set_info_map *map0 = m0;
	const struct nfit_set_info_map *map1 = m1;

	return memcmp(&map0->region_offset, &map1->region_offset,
			sizeof(u64));
}

/* Retrieve the nth entry referencing this spa */
static struct acpi_nfit_memory_map *memdev_from_spa(
		struct acpi_nfit_desc *acpi_desc, u16 range_index, int n)
{
	struct nfit_memdev *nfit_memdev;

	list_for_each_entry(nfit_memdev, &acpi_desc->memdevs, list)
		if (nfit_memdev->memdev->range_index == range_index)
			if (n-- == 0)
				return nfit_memdev->memdev;
	return NULL;
}

static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
		struct nd_region_desc *ndr_desc,
		struct acpi_nfit_system_address *spa)
{
	int i, spa_type = nfit_spa_type(spa);
	struct device *dev = acpi_desc->dev;
	struct nd_interleave_set *nd_set;
	u16 nr = ndr_desc->num_mappings;
	struct nfit_set_info *info;

	if (spa_type == NFIT_SPA_PM || spa_type == NFIT_SPA_VOLATILE)
		/* pass */;
	else
		return 0;

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

	info = devm_kzalloc(dev, sizeof_nfit_set_info(nr), GFP_KERNEL);
	if (!info)
		return -ENOMEM;
	for (i = 0; i < nr; i++) {
		struct nd_mapping *nd_mapping = &ndr_desc->nd_mapping[i];
		struct nfit_set_info_map *map = &info->mapping[i];
		struct nvdimm *nvdimm = nd_mapping->nvdimm;
		struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm);
		struct acpi_nfit_memory_map *memdev = memdev_from_spa(acpi_desc,
				spa->range_index, i);

		if (!memdev || !nfit_mem->dcr) {
			dev_err(dev, "%s: failed to find DCR\n", __func__);
			return -ENODEV;
		}

		map->region_offset = memdev->region_offset;
		map->serial_number = nfit_mem->dcr->serial_number;
	}

	sort(&info->mapping[0], nr, sizeof(struct nfit_set_info_map),
			cmp_map, NULL);
	nd_set->cookie = nd_fletcher64(info, sizeof_nfit_set_info(nr), 0);
	ndr_desc->nd_set = nd_set;
	devm_kfree(dev, info);

	return 0;
}

static u64 to_interleave_offset(u64 offset, struct nfit_blk_mmio *mmio)
{
	struct acpi_nfit_interleave *idt = mmio->idt;
	u32 sub_line_offset, line_index, line_offset;
	u64 line_no, table_skip_count, table_offset;

	line_no = div_u64_rem(offset, mmio->line_size, &sub_line_offset);
	table_skip_count = div_u64_rem(line_no, mmio->num_lines, &line_index);
	line_offset = idt->line_offset[line_index]
		* mmio->line_size;
	table_offset = table_skip_count * mmio->table_size;

	return mmio->base_offset + line_offset + table_offset + sub_line_offset;
}

static void wmb_blk(struct nfit_blk *nfit_blk)
{

	if (nfit_blk->nvdimm_flush) {
		/*
		 * The first wmb() is needed to 'sfence' all previous writes
		 * such that they are architecturally visible for the platform
		 * buffer flush.  Note that we've already arranged for pmem
		 * writes to avoid the cache via arch_memcpy_to_pmem().  The
		 * final wmb() ensures ordering for the NVDIMM flush write.
		 */
		wmb();
		writeq(1, nfit_blk->nvdimm_flush);
		wmb();
	} else
		wmb_pmem();
}

static u32 read_blk_stat(struct nfit_blk *nfit_blk, unsigned int bw)
{
	struct nfit_blk_mmio *mmio = &nfit_blk->mmio[DCR];
	u64 offset = nfit_blk->stat_offset + mmio->size * bw;

	if (mmio->num_lines)
		offset = to_interleave_offset(offset, mmio);

	return readl(mmio->addr.base + offset);
}

static void write_blk_ctl(struct nfit_blk *nfit_blk, unsigned int bw,
		resource_size_t dpa, unsigned int len, unsigned int write)
{
	u64 cmd, offset;
	struct nfit_blk_mmio *mmio = &nfit_blk->mmio[DCR];

	enum {
		BCW_OFFSET_MASK = (1ULL << 48)-1,
		BCW_LEN_SHIFT = 48,
		BCW_LEN_MASK = (1ULL << 8) - 1,
		BCW_CMD_SHIFT = 56,
	};

	cmd = (dpa >> L1_CACHE_SHIFT) & BCW_OFFSET_MASK;
	len = len >> L1_CACHE_SHIFT;
	cmd |= ((u64) len & BCW_LEN_MASK) << BCW_LEN_SHIFT;
	cmd |= ((u64) write) << BCW_CMD_SHIFT;

	offset = nfit_blk->cmd_offset + mmio->size * bw;
	if (mmio->num_lines)
		offset = to_interleave_offset(offset, mmio);

	writeq(cmd, mmio->addr.base + offset);
	wmb_blk(nfit_blk);

	if (nfit_blk->dimm_flags & NFIT_BLK_DCR_LATCH)
		readq(mmio->addr.base + offset);
}

static int acpi_nfit_blk_single_io(struct nfit_blk *nfit_blk,
		resource_size_t dpa, void *iobuf, size_t len, int rw,
		unsigned int lane)
{
	struct nfit_blk_mmio *mmio = &nfit_blk->mmio[BDW];
	unsigned int copied = 0;
	u64 base_offset;
	int rc;

	base_offset = nfit_blk->bdw_offset + dpa % L1_CACHE_BYTES
		+ lane * mmio->size;
	write_blk_ctl(nfit_blk, lane, dpa, len, rw);
	while (len) {
		unsigned int c;
		u64 offset;

		if (mmio->num_lines) {
			u32 line_offset;

			offset = to_interleave_offset(base_offset + copied,
					mmio);
			div_u64_rem(offset, mmio->line_size, &line_offset);
			c = min_t(size_t, len, mmio->line_size - line_offset);
		} else {
			offset = base_offset + nfit_blk->bdw_offset;
			c = len;
		}

		if (rw)
			memcpy_to_pmem(mmio->addr.aperture + offset,
					iobuf + copied, c);
		else {
			if (nfit_blk->dimm_flags & NFIT_BLK_READ_FLUSH)
				mmio_flush_range((void __force *)
					mmio->addr.aperture + offset, c);

			memcpy_from_pmem(iobuf + copied,
					mmio->addr.aperture + offset, c);
		}

		copied += c;
		len -= c;
	}

	if (rw)
		wmb_blk(nfit_blk);

	rc = read_blk_stat(nfit_blk, lane) ? -EIO : 0;
	return rc;
}

static int acpi_nfit_blk_region_do_io(struct nd_blk_region *ndbr,
		resource_size_t dpa, void *iobuf, u64 len, int rw)
{
	struct nfit_blk *nfit_blk = nd_blk_region_provider_data(ndbr);
	struct nfit_blk_mmio *mmio = &nfit_blk->mmio[BDW];
	struct nd_region *nd_region = nfit_blk->nd_region;
	unsigned int lane, copied = 0;
	int rc = 0;

	lane = nd_region_acquire_lane(nd_region);
	while (len) {
		u64 c = min(len, mmio->size);

		rc = acpi_nfit_blk_single_io(nfit_blk, dpa + copied,
				iobuf + copied, c, rw, lane);
		if (rc)
			break;

		copied += c;
		len -= c;
	}
	nd_region_release_lane(nd_region, lane);

	return rc;
}

static void nfit_spa_mapping_release(struct kref *kref)
{
	struct nfit_spa_mapping *spa_map = to_spa_map(kref);
	struct acpi_nfit_system_address *spa = spa_map->spa;
	struct acpi_nfit_desc *acpi_desc = spa_map->acpi_desc;

	WARN_ON(!mutex_is_locked(&acpi_desc->spa_map_mutex));
	dev_dbg(acpi_desc->dev, "%s: SPA%d\n", __func__, spa->range_index);
	if (spa_map->type == SPA_MAP_APERTURE)
		memunmap((void __force *)spa_map->addr.aperture);
	else
		iounmap(spa_map->addr.base);
	release_mem_region(spa->address, spa->length);
	list_del(&spa_map->list);
	kfree(spa_map);
}

static struct nfit_spa_mapping *find_spa_mapping(
		struct acpi_nfit_desc *acpi_desc,
		struct acpi_nfit_system_address *spa)
{
	struct nfit_spa_mapping *spa_map;

	WARN_ON(!mutex_is_locked(&acpi_desc->spa_map_mutex));
	list_for_each_entry(spa_map, &acpi_desc->spa_maps, list)
		if (spa_map->spa == spa)
			return spa_map;

	return NULL;
}

static void nfit_spa_unmap(struct acpi_nfit_desc *acpi_desc,
		struct acpi_nfit_system_address *spa)
{
	struct nfit_spa_mapping *spa_map;

	mutex_lock(&acpi_desc->spa_map_mutex);
	spa_map = find_spa_mapping(acpi_desc, spa);

	if (spa_map)
		kref_put(&spa_map->kref, nfit_spa_mapping_release);
	mutex_unlock(&acpi_desc->spa_map_mutex);
}

static void __iomem *__nfit_spa_map(struct acpi_nfit_desc *acpi_desc,
		struct acpi_nfit_system_address *spa, enum spa_map_type type)
{
	resource_size_t start = spa->address;
	resource_size_t n = spa->length;
	struct nfit_spa_mapping *spa_map;
	struct resource *res;

	WARN_ON(!mutex_is_locked(&acpi_desc->spa_map_mutex));

	spa_map = find_spa_mapping(acpi_desc, spa);
	if (spa_map) {
		kref_get(&spa_map->kref);
		return spa_map->addr.base;
	}

	spa_map = kzalloc(sizeof(*spa_map), GFP_KERNEL);
	if (!spa_map)
		return NULL;

	INIT_LIST_HEAD(&spa_map->list);
	spa_map->spa = spa;
	kref_init(&spa_map->kref);
	spa_map->acpi_desc = acpi_desc;

	res = request_mem_region(start, n, dev_name(acpi_desc->dev));
	if (!res)
		goto err_mem;

	spa_map->type = type;
	if (type == SPA_MAP_APERTURE)
		spa_map->addr.aperture = (void __pmem *)memremap(start, n,
							ARCH_MEMREMAP_PMEM);
	else
		spa_map->addr.base = ioremap_nocache(start, n);


	if (!spa_map->addr.base)
		goto err_map;

	list_add_tail(&spa_map->list, &acpi_desc->spa_maps);
	return spa_map->addr.base;

 err_map:
	release_mem_region(start, n);
 err_mem:
	kfree(spa_map);
	return NULL;
}

/**
 * nfit_spa_map - interleave-aware managed-mappings of acpi_nfit_system_address ranges
 * @nvdimm_bus: NFIT-bus that provided the spa table entry
 * @nfit_spa: spa table to map
 * @type: aperture or control region
 *
 * In the case where block-data-window apertures and
 * dimm-control-regions are interleaved they will end up sharing a
 * single request_mem_region() + ioremap() for the address range.  In
 * the style of devm nfit_spa_map() mappings are automatically dropped
 * when all region devices referencing the same mapping are disabled /
 * unbound.
 */
static void __iomem *nfit_spa_map(struct acpi_nfit_desc *acpi_desc,
		struct acpi_nfit_system_address *spa, enum spa_map_type type)
{
	void __iomem *iomem;

	mutex_lock(&acpi_desc->spa_map_mutex);
	iomem = __nfit_spa_map(acpi_desc, spa, type);
	mutex_unlock(&acpi_desc->spa_map_mutex);

	return iomem;
}

static int nfit_blk_init_interleave(struct nfit_blk_mmio *mmio,
		struct acpi_nfit_interleave *idt, u16 interleave_ways)
{
	if (idt) {
		mmio->num_lines = idt->line_count;
		mmio->line_size = idt->line_size;
		if (interleave_ways == 0)
			return -ENXIO;
		mmio->table_size = mmio->num_lines * interleave_ways
			* mmio->line_size;
	}

	return 0;
}

static int acpi_nfit_blk_get_flags(struct nvdimm_bus_descriptor *nd_desc,
		struct nvdimm *nvdimm, struct nfit_blk *nfit_blk)
{
	struct nd_cmd_dimm_flags flags;
	int rc;

	memset(&flags, 0, sizeof(flags));
	rc = nd_desc->ndctl(nd_desc, nvdimm, ND_CMD_DIMM_FLAGS, &flags,
			sizeof(flags), NULL);

	if (rc >= 0 && flags.status == 0)
		nfit_blk->dimm_flags = flags.flags;
	else if (rc == -ENOTTY) {
		/* fall back to a conservative default */
		nfit_blk->dimm_flags = NFIT_BLK_DCR_LATCH | NFIT_BLK_READ_FLUSH;
		rc = 0;
	} else
		rc = -ENXIO;

	return rc;
}

static int acpi_nfit_blk_region_enable(struct nvdimm_bus *nvdimm_bus,
		struct device *dev)
{
	struct nvdimm_bus_descriptor *nd_desc = to_nd_desc(nvdimm_bus);
	struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);
	struct nd_blk_region *ndbr = to_nd_blk_region(dev);
	struct nfit_flush *nfit_flush;
	struct nfit_blk_mmio *mmio;
	struct nfit_blk *nfit_blk;
	struct nfit_mem *nfit_mem;
	struct nvdimm *nvdimm;
	int rc;

	nvdimm = nd_blk_region_to_dimm(ndbr);
	nfit_mem = nvdimm_provider_data(nvdimm);
	if (!nfit_mem || !nfit_mem->dcr || !nfit_mem->bdw) {
		dev_dbg(dev, "%s: missing%s%s%s\n", __func__,
				nfit_mem ? "" : " nfit_mem",
				(nfit_mem && nfit_mem->dcr) ? "" : " dcr",
				(nfit_mem && nfit_mem->bdw) ? "" : " bdw");
		return -ENXIO;
	}

	nfit_blk = devm_kzalloc(dev, sizeof(*nfit_blk), GFP_KERNEL);
	if (!nfit_blk)
		return -ENOMEM;
	nd_blk_region_set_provider_data(ndbr, nfit_blk);
	nfit_blk->nd_region = to_nd_region(dev);

	/* map block aperture memory */
	nfit_blk->bdw_offset = nfit_mem->bdw->offset;
	mmio = &nfit_blk->mmio[BDW];
	mmio->addr.base = nfit_spa_map(acpi_desc, nfit_mem->spa_bdw,
			SPA_MAP_APERTURE);
	if (!mmio->addr.base) {
		dev_dbg(dev, "%s: %s failed to map bdw\n", __func__,
				nvdimm_name(nvdimm));
		return -ENOMEM;
	}
	mmio->size = nfit_mem->bdw->size;
	mmio->base_offset = nfit_mem->memdev_bdw->region_offset;
	mmio->idt = nfit_mem->idt_bdw;
	mmio->spa = nfit_mem->spa_bdw;
	rc = nfit_blk_init_interleave(mmio, nfit_mem->idt_bdw,
			nfit_mem->memdev_bdw->interleave_ways);
	if (rc) {
		dev_dbg(dev, "%s: %s failed to init bdw interleave\n",
				__func__, nvdimm_name(nvdimm));
		return rc;
	}

	/* map block control memory */
	nfit_blk->cmd_offset = nfit_mem->dcr->command_offset;
	nfit_blk->stat_offset = nfit_mem->dcr->status_offset;
	mmio = &nfit_blk->mmio[DCR];
	mmio->addr.base = nfit_spa_map(acpi_desc, nfit_mem->spa_dcr,
			SPA_MAP_CONTROL);
	if (!mmio->addr.base) {
		dev_dbg(dev, "%s: %s failed to map dcr\n", __func__,
				nvdimm_name(nvdimm));
		return -ENOMEM;
	}
	mmio->size = nfit_mem->dcr->window_size;
	mmio->base_offset = nfit_mem->memdev_dcr->region_offset;
	mmio->idt = nfit_mem->idt_dcr;
	mmio->spa = nfit_mem->spa_dcr;
	rc = nfit_blk_init_interleave(mmio, nfit_mem->idt_dcr,
			nfit_mem->memdev_dcr->interleave_ways);
	if (rc) {
		dev_dbg(dev, "%s: %s failed to init dcr interleave\n",
				__func__, nvdimm_name(nvdimm));
		return rc;
	}

	rc = acpi_nfit_blk_get_flags(nd_desc, nvdimm, nfit_blk);
	if (rc < 0) {
		dev_dbg(dev, "%s: %s failed get DIMM flags\n",
				__func__, nvdimm_name(nvdimm));
		return rc;
	}

	nfit_flush = nfit_mem->nfit_flush;
	if (nfit_flush && nfit_flush->flush->hint_count != 0) {
		nfit_blk->nvdimm_flush = devm_ioremap_nocache(dev,
				nfit_flush->flush->hint_address[0], 8);
		if (!nfit_blk->nvdimm_flush)
			return -ENOMEM;
	}

	if (!arch_has_wmb_pmem() && !nfit_blk->nvdimm_flush)
		dev_warn(dev, "unable to guarantee persistence of writes\n");

	if (mmio->line_size == 0)
		return 0;

	if ((u32) nfit_blk->cmd_offset % mmio->line_size
			+ 8 > mmio->line_size) {
		dev_dbg(dev, "cmd_offset crosses interleave boundary\n");
		return -ENXIO;
	} else if ((u32) nfit_blk->stat_offset % mmio->line_size
			+ 8 > mmio->line_size) {
		dev_dbg(dev, "stat_offset crosses interleave boundary\n");
		return -ENXIO;
	}

	return 0;
}

static void acpi_nfit_blk_region_disable(struct nvdimm_bus *nvdimm_bus,
		struct device *dev)
{
	struct nvdimm_bus_descriptor *nd_desc = to_nd_desc(nvdimm_bus);
	struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);
	struct nd_blk_region *ndbr = to_nd_blk_region(dev);
	struct nfit_blk *nfit_blk = nd_blk_region_provider_data(ndbr);
	int i;

	if (!nfit_blk)
		return; /* never enabled */

	/* auto-free BLK spa mappings */
	for (i = 0; i < 2; i++) {
		struct nfit_blk_mmio *mmio = &nfit_blk->mmio[i];

		if (mmio->addr.base)
			nfit_spa_unmap(acpi_desc, mmio->spa);
	}
	nd_blk_region_set_provider_data(ndbr, NULL);
	/* devm will free nfit_blk */
}

static int ars_get_cap(struct acpi_nfit_desc *acpi_desc,
		struct nd_cmd_ars_cap *cmd, u64 addr, u64 length)
{
	struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc;
	int cmd_rc, rc;

	cmd->address = addr;
	cmd->length = length;
	rc = nd_desc->ndctl(nd_desc, NULL, ND_CMD_ARS_CAP, cmd,
			sizeof(*cmd), &cmd_rc);
	if (rc < 0)
		return rc;
	if (cmd_rc < 0)
		return cmd_rc;
	return 0;
}

static int ars_do_start(struct nvdimm_bus_descriptor *nd_desc,
		struct nd_cmd_ars_start *cmd, u64 addr, u64 length)
{
	int cmd_rc;
	int rc;

	cmd->address = addr;
	cmd->length = length;
	cmd->type = ND_ARS_PERSISTENT;

	while (1) {
		rc = nd_desc->ndctl(nd_desc, NULL, ND_CMD_ARS_START, cmd,
				sizeof(*cmd), &cmd_rc);

		if (rc < 0)
			return rc;

		if (cmd_rc == -EBUSY) {
			/* ARS is in progress */
			msleep(1000);
			continue;
		}

		if (cmd_rc < 0)
			return cmd_rc;

		return 0;
	}
}

static int ars_get_status(struct nvdimm_bus_descriptor *nd_desc,
		struct nd_cmd_ars_status *cmd, u32 size)
{
	int rc, cmd_rc;

	while (1) {
		rc = nd_desc->ndctl(nd_desc, NULL, ND_CMD_ARS_STATUS, cmd,
			size, &cmd_rc);
		if (rc < 0)
			return rc;

		/* FIXME make async and have a timeout */
		if (cmd_rc == -EBUSY) {
			msleep(1000);
			continue;
		}

		if (cmd_rc == -EAGAIN || cmd_rc == 0)
			return 0;

		/* TODO: error list overflow support */
		if (cmd_rc == -ENOSPC)
			return -ENXIO;

		return cmd_rc;
	}
}

static int ars_status_process_records(struct nvdimm_bus *nvdimm_bus,
		struct nd_cmd_ars_status *ars_status, u64 start)
{
	int rc;
	u32 i;

	/*
	 * The address field returned by ars_status should be either
	 * less than or equal to the address we last started ARS for.
	 * The (start, length) returned by ars_status should also have
	 * non-zero overlap with the range we started ARS for.
	 * If this is not the case, bail.
	 */
	if (ars_status->address > start ||
			(ars_status->address + ars_status->length < start))
		return -ENXIO;

	for (i = 0; i < ars_status->num_records; i++) {
		rc = nvdimm_bus_add_poison(nvdimm_bus,
				ars_status->records[i].err_address,
				ars_status->records[i].length);
		if (rc)
			return rc;
	}

	return 0;
}

static int acpi_nfit_find_poison(struct acpi_nfit_desc *acpi_desc,
		struct nd_region_desc *ndr_desc)
{
	struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc;
	struct nvdimm_bus *nvdimm_bus = acpi_desc->nvdimm_bus;
	struct nd_cmd_ars_status *ars_status = NULL;
	struct nd_cmd_ars_start *ars_start = NULL;
	struct nd_cmd_ars_cap *ars_cap = NULL;
	u64 start, len, cur, remaining;
	u32 ars_status_size;
	int rc;

	ars_cap = kzalloc(sizeof(*ars_cap), GFP_KERNEL);
	if (!ars_cap)
		return -ENOMEM;

	start = ndr_desc->res->start;
	len = ndr_desc->res->end - ndr_desc->res->start + 1;

	rc = ars_get_cap(acpi_desc, ars_cap, start, len);
	if (rc == -ENOTTY) {
		rc = 0;
		goto out;
	}

	/*
	 * Check if a full-range ARS has been run. If so, use those results
	 * without having to start a new ARS.
	 */
	ars_status_size = ars_cap->max_ars_out;
	ars_status = kzalloc(ars_status_size, GFP_KERNEL);
	if (!ars_status) {
		rc = -ENOMEM;
		goto out;
	}

	rc = ars_get_status(nd_desc, ars_status, ars_status_size);
	if (rc)
		goto out;

	if (ars_status->address <= start &&
		(ars_status->address + ars_status->length >= start + len)) {
		rc = ars_status_process_records(nvdimm_bus, ars_status, start);
		goto out;
	}

	/*
	 * ARS_STATUS can overflow if the number of poison entries found is
	 * greater than the maximum buffer size (ars_cap->max_ars_out)
	 * To detect overflow, check if the length field of ars_status
	 * is less than the length we supplied. If so, process the
	 * error entries we got, adjust the start point, and start again
	 */
	ars_start = kzalloc(sizeof(*ars_start), GFP_KERNEL);
	if (!ars_start)
		return -ENOMEM;

	cur = start;
	remaining = len;
	do {
		u64 done, end;

		rc = ars_do_start(nd_desc, ars_start, cur, remaining);
		if (rc < 0)
			goto out;

		rc = ars_get_status(nd_desc, ars_status, ars_status_size);
		if (rc < 0)
			goto out;

		rc = ars_status_process_records(nvdimm_bus, ars_status, cur);
		if (rc < 0)
			goto out;

		end = min(cur + remaining,
			ars_status->address + ars_status->length);
		done = end - cur;
		cur += done;
		remaining -= done;
	} while (remaining);

 out:
	kfree(ars_cap);
	kfree(ars_start);
	kfree(ars_status);
	return rc;
}

static int acpi_nfit_init_mapping(struct acpi_nfit_desc *acpi_desc,
		struct nd_mapping *nd_mapping, struct nd_region_desc *ndr_desc,
		struct acpi_nfit_memory_map *memdev,
		struct acpi_nfit_system_address *spa)
{
	struct nvdimm *nvdimm = acpi_nfit_dimm_by_handle(acpi_desc,
			memdev->device_handle);
	struct nd_blk_region_desc *ndbr_desc;
	struct nfit_mem *nfit_mem;
	int blk_valid = 0;

	if (!nvdimm) {
		dev_err(acpi_desc->dev, "spa%d dimm: %#x not found\n",
				spa->range_index, memdev->device_handle);
		return -ENODEV;
	}

	nd_mapping->nvdimm = nvdimm;
	switch (nfit_spa_type(spa)) {
	case NFIT_SPA_PM:
	case NFIT_SPA_VOLATILE:
		nd_mapping->start = memdev->address;
		nd_mapping->size = memdev->region_size;
		break;
	case NFIT_SPA_DCR:
		nfit_mem = nvdimm_provider_data(nvdimm);
		if (!nfit_mem || !nfit_mem->bdw) {
			dev_dbg(acpi_desc->dev, "spa%d %s missing bdw\n",
					spa->range_index, nvdimm_name(nvdimm));
		} else {
			nd_mapping->size = nfit_mem->bdw->capacity;
			nd_mapping->start = nfit_mem->bdw->start_address;
			ndr_desc->num_lanes = nfit_mem->bdw->windows;
			blk_valid = 1;
		}

		ndr_desc->nd_mapping = nd_mapping;
		ndr_desc->num_mappings = blk_valid;
		ndbr_desc = to_blk_region_desc(ndr_desc);
		ndbr_desc->enable = acpi_nfit_blk_region_enable;
		ndbr_desc->disable = acpi_nfit_blk_region_disable;
		ndbr_desc->do_io = acpi_desc->blk_do_io;
		if (!nvdimm_blk_region_create(acpi_desc->nvdimm_bus, ndr_desc))
			return -ENOMEM;
		break;
	}

	return 0;
}

static int acpi_nfit_register_region(struct acpi_nfit_desc *acpi_desc,
		struct nfit_spa *nfit_spa)
{
	static struct nd_mapping nd_mappings[ND_MAX_MAPPINGS];
	struct acpi_nfit_system_address *spa = nfit_spa->spa;
	struct nd_blk_region_desc ndbr_desc;
	struct nd_region_desc *ndr_desc;
	struct nfit_memdev *nfit_memdev;
	struct nvdimm_bus *nvdimm_bus;
	struct resource res;
	int count = 0, rc;

	if (nfit_spa->is_registered)
		return 0;

	if (spa->range_index == 0) {
		dev_dbg(acpi_desc->dev, "%s: detected invalid spa index\n",
				__func__);
		return 0;
	}

	memset(&res, 0, sizeof(res));
	memset(&nd_mappings, 0, sizeof(nd_mappings));
	memset(&ndbr_desc, 0, sizeof(ndbr_desc));
	res.start = spa->address;
	res.end = res.start + spa->length - 1;
	ndr_desc = &ndbr_desc.ndr_desc;
	ndr_desc->res = &res;
	ndr_desc->provider_data = nfit_spa;
	ndr_desc->attr_groups = acpi_nfit_region_attribute_groups;
	if (spa->flags & ACPI_NFIT_PROXIMITY_VALID)
		ndr_desc->numa_node = acpi_map_pxm_to_online_node(
						spa->proximity_domain);
	else
		ndr_desc->numa_node = NUMA_NO_NODE;

	list_for_each_entry(nfit_memdev, &acpi_desc->memdevs, list) {
		struct acpi_nfit_memory_map *memdev = nfit_memdev->memdev;
		struct nd_mapping *nd_mapping;

		if (memdev->range_index != spa->range_index)
			continue;
		if (count >= ND_MAX_MAPPINGS) {
			dev_err(acpi_desc->dev, "spa%d exceeds max mappings %d\n",
					spa->range_index, ND_MAX_MAPPINGS);
			return -ENXIO;
		}
		nd_mapping = &nd_mappings[count++];
		rc = acpi_nfit_init_mapping(acpi_desc, nd_mapping, ndr_desc,
				memdev, spa);
		if (rc)
			return rc;
	}

	ndr_desc->nd_mapping = nd_mappings;
	ndr_desc->num_mappings = count;
	rc = acpi_nfit_init_interleave_set(acpi_desc, ndr_desc, spa);
	if (rc)
		return rc;

	nvdimm_bus = acpi_desc->nvdimm_bus;
	if (nfit_spa_type(spa) == NFIT_SPA_PM) {
		rc = acpi_nfit_find_poison(acpi_desc, ndr_desc);
		if (rc) {
			dev_err(acpi_desc->dev,
				"error while performing ARS to find poison: %d\n",
				rc);
			return rc;
		}
		if (!nvdimm_pmem_region_create(nvdimm_bus, ndr_desc))
			return -ENOMEM;
	} else if (nfit_spa_type(spa) == NFIT_SPA_VOLATILE) {
		if (!nvdimm_volatile_region_create(nvdimm_bus, ndr_desc))
			return -ENOMEM;
	}

	nfit_spa->is_registered = 1;
	return 0;
}

static int acpi_nfit_register_regions(struct acpi_nfit_desc *acpi_desc)
{
	struct nfit_spa *nfit_spa;

	list_for_each_entry(nfit_spa, &acpi_desc->spas, list) {
		int rc = acpi_nfit_register_region(acpi_desc, nfit_spa);

		if (rc)
			return rc;
	}
	return 0;
}

static int acpi_nfit_check_deletions(struct acpi_nfit_desc *acpi_desc,
		struct nfit_table_prev *prev)
{
	struct device *dev = acpi_desc->dev;

	if (!list_empty(&prev->spas) ||
			!list_empty(&prev->memdevs) ||
			!list_empty(&prev->dcrs) ||
			!list_empty(&prev->bdws) ||
			!list_empty(&prev->idts) ||
			!list_empty(&prev->flushes)) {
		dev_err(dev, "new nfit deletes entries (unsupported)\n");
		return -ENXIO;
	}
	return 0;
}

int acpi_nfit_init(struct acpi_nfit_desc *acpi_desc, acpi_size sz)
{
	struct device *dev = acpi_desc->dev;
	struct nfit_table_prev prev;
	const void *end;
	u8 *data;
	int rc;

	mutex_lock(&acpi_desc->init_mutex);

	INIT_LIST_HEAD(&prev.spas);
	INIT_LIST_HEAD(&prev.memdevs);
	INIT_LIST_HEAD(&prev.dcrs);
	INIT_LIST_HEAD(&prev.bdws);
	INIT_LIST_HEAD(&prev.idts);
	INIT_LIST_HEAD(&prev.flushes);

	list_cut_position(&prev.spas, &acpi_desc->spas,
				acpi_desc->spas.prev);
	list_cut_position(&prev.memdevs, &acpi_desc->memdevs,
				acpi_desc->memdevs.prev);
	list_cut_position(&prev.dcrs, &acpi_desc->dcrs,
				acpi_desc->dcrs.prev);
	list_cut_position(&prev.bdws, &acpi_desc->bdws,
				acpi_desc->bdws.prev);
	list_cut_position(&prev.idts, &acpi_desc->idts,
				acpi_desc->idts.prev);
	list_cut_position(&prev.flushes, &acpi_desc->flushes,
				acpi_desc->flushes.prev);

	data = (u8 *) acpi_desc->nfit;
	end = data + sz;
	while (!IS_ERR_OR_NULL(data))
		data = add_table(acpi_desc, &prev, data, end);

	if (IS_ERR(data)) {
		dev_dbg(dev, "%s: nfit table parsing error: %ld\n", __func__,
				PTR_ERR(data));
		rc = PTR_ERR(data);
		goto out_unlock;
	}

	rc = acpi_nfit_check_deletions(acpi_desc, &prev);
	if (rc)
		goto out_unlock;

	if (nfit_mem_init(acpi_desc) != 0) {
		rc = -ENOMEM;
		goto out_unlock;
	}

	acpi_nfit_init_dsms(acpi_desc);

	rc = acpi_nfit_register_dimms(acpi_desc);
	if (rc)
		goto out_unlock;

	rc = acpi_nfit_register_regions(acpi_desc);

 out_unlock:
	mutex_unlock(&acpi_desc->init_mutex);
	return rc;
}
EXPORT_SYMBOL_GPL(acpi_nfit_init);

void acpi_nfit_desc_init(struct acpi_nfit_desc *acpi_desc, struct device *dev)
{
	struct nvdimm_bus_descriptor *nd_desc;

	dev_set_drvdata(dev, acpi_desc);
	acpi_desc->dev = dev;
	acpi_desc->blk_do_io = acpi_nfit_blk_region_do_io;
	nd_desc = &acpi_desc->nd_desc;
	nd_desc->provider_name = "ACPI.NFIT";
	nd_desc->ndctl = acpi_nfit_ctl;
	nd_desc->attr_groups = acpi_nfit_attribute_groups;

	INIT_LIST_HEAD(&acpi_desc->spa_maps);
	INIT_LIST_HEAD(&acpi_desc->spas);
	INIT_LIST_HEAD(&acpi_desc->dcrs);
	INIT_LIST_HEAD(&acpi_desc->bdws);
	INIT_LIST_HEAD(&acpi_desc->idts);
	INIT_LIST_HEAD(&acpi_desc->flushes);
	INIT_LIST_HEAD(&acpi_desc->memdevs);
	INIT_LIST_HEAD(&acpi_desc->dimms);
	mutex_init(&acpi_desc->spa_map_mutex);
	mutex_init(&acpi_desc->init_mutex);
}
EXPORT_SYMBOL_GPL(acpi_nfit_desc_init);

static int acpi_nfit_add(struct acpi_device *adev)
{
	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
	struct acpi_nfit_desc *acpi_desc;
	struct device *dev = &adev->dev;
	struct acpi_table_header *tbl;
	acpi_status status = AE_OK;
	acpi_size sz;
	int rc;

	status = acpi_get_table_with_size("NFIT", 0, &tbl, &sz);
	if (ACPI_FAILURE(status)) {
		/* This is ok, we could have an nvdimm hotplugged later */
		dev_dbg(dev, "failed to find NFIT at startup\n");
		return 0;
	}

	acpi_desc = devm_kzalloc(dev, sizeof(*acpi_desc), GFP_KERNEL);
	if (!acpi_desc)
		return -ENOMEM;
	acpi_nfit_desc_init(acpi_desc, &adev->dev);
	acpi_desc->nvdimm_bus = nvdimm_bus_register(dev, &acpi_desc->nd_desc);
	if (!acpi_desc->nvdimm_bus)
		return -ENOMEM;

	/*
	 * Save the acpi header for later and then skip it,
	 * making nfit point to the first nfit table header.
	 */
	acpi_desc->acpi_header = *tbl;
	acpi_desc->nfit = (void *) tbl + sizeof(struct acpi_table_nfit);
	sz -= sizeof(struct acpi_table_nfit);

	/* Evaluate _FIT and override with that if present */
	status = acpi_evaluate_object(adev->handle, "_FIT", NULL, &buf);
	if (ACPI_SUCCESS(status) && buf.length > 0) {
		union acpi_object *obj;
		/*
		 * Adjust for the acpi_object header of the _FIT
		 */
		obj = buf.pointer;
		if (obj->type == ACPI_TYPE_BUFFER) {
			acpi_desc->nfit =
				(struct acpi_nfit_header *)obj->buffer.pointer;
			sz = obj->buffer.length;
		} else
			dev_dbg(dev, "%s invalid type %d, ignoring _FIT\n",
				 __func__, (int) obj->type);
	}

	rc = acpi_nfit_init(acpi_desc, sz);
	if (rc) {
		nvdimm_bus_unregister(acpi_desc->nvdimm_bus);
		return rc;
	}
	return 0;
}

static int acpi_nfit_remove(struct acpi_device *adev)
{
	struct acpi_nfit_desc *acpi_desc = dev_get_drvdata(&adev->dev);

	nvdimm_bus_unregister(acpi_desc->nvdimm_bus);
	return 0;
}

static void acpi_nfit_notify(struct acpi_device *adev, u32 event)
{
	struct acpi_nfit_desc *acpi_desc = dev_get_drvdata(&adev->dev);
	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
	struct acpi_nfit_header *nfit_saved;
	union acpi_object *obj;
	struct device *dev = &adev->dev;
	acpi_status status;
	int ret;

	dev_dbg(dev, "%s: event: %d\n", __func__, event);

	device_lock(dev);
	if (!dev->driver) {
		/* dev->driver may be null if we're being removed */
		dev_dbg(dev, "%s: no driver found for dev\n", __func__);
		goto out_unlock;
	}

	if (!acpi_desc) {
		acpi_desc = devm_kzalloc(dev, sizeof(*acpi_desc), GFP_KERNEL);
		if (!acpi_desc)
			goto out_unlock;
		acpi_nfit_desc_init(acpi_desc, &adev->dev);
		acpi_desc->nvdimm_bus = nvdimm_bus_register(dev, &acpi_desc->nd_desc);
		if (!acpi_desc->nvdimm_bus)
			goto out_unlock;
	}

	/* Evaluate _FIT */
	status = acpi_evaluate_object(adev->handle, "_FIT", NULL, &buf);
	if (ACPI_FAILURE(status)) {
		dev_err(dev, "failed to evaluate _FIT\n");
		goto out_unlock;
	}

	nfit_saved = acpi_desc->nfit;
	obj = buf.pointer;
	if (obj->type == ACPI_TYPE_BUFFER) {
		acpi_desc->nfit =
			(struct acpi_nfit_header *)obj->buffer.pointer;
		ret = acpi_nfit_init(acpi_desc, obj->buffer.length);
		if (ret) {
			/* Merge failed, restore old nfit, and exit */
			acpi_desc->nfit = nfit_saved;
			dev_err(dev, "failed to merge updated NFIT\n");
		}
	} else {
		/* Bad _FIT, restore old nfit */
		dev_err(dev, "Invalid _FIT\n");
	}
	kfree(buf.pointer);

 out_unlock:
	device_unlock(dev);
}

static const struct acpi_device_id acpi_nfit_ids[] = {
	{ "ACPI0012", 0 },
	{ "", 0 },
};
MODULE_DEVICE_TABLE(acpi, acpi_nfit_ids);

static struct acpi_driver acpi_nfit_driver = {
	.name = KBUILD_MODNAME,
	.ids = acpi_nfit_ids,
	.ops = {
		.add = acpi_nfit_add,
		.remove = acpi_nfit_remove,
		.notify = acpi_nfit_notify,
	},
};

static __init int nfit_init(void)
{
	BUILD_BUG_ON(sizeof(struct acpi_table_nfit) != 40);
	BUILD_BUG_ON(sizeof(struct acpi_nfit_system_address) != 56);
	BUILD_BUG_ON(sizeof(struct acpi_nfit_memory_map) != 48);
	BUILD_BUG_ON(sizeof(struct acpi_nfit_interleave) != 20);
	BUILD_BUG_ON(sizeof(struct acpi_nfit_smbios) != 9);
	BUILD_BUG_ON(sizeof(struct acpi_nfit_control_region) != 80);
	BUILD_BUG_ON(sizeof(struct acpi_nfit_data_region) != 40);

	acpi_str_to_uuid(UUID_VOLATILE_MEMORY, nfit_uuid[NFIT_SPA_VOLATILE]);
	acpi_str_to_uuid(UUID_PERSISTENT_MEMORY, nfit_uuid[NFIT_SPA_PM]);
	acpi_str_to_uuid(UUID_CONTROL_REGION, nfit_uuid[NFIT_SPA_DCR]);
	acpi_str_to_uuid(UUID_DATA_REGION, nfit_uuid[NFIT_SPA_BDW]);
	acpi_str_to_uuid(UUID_VOLATILE_VIRTUAL_DISK, nfit_uuid[NFIT_SPA_VDISK]);
	acpi_str_to_uuid(UUID_VOLATILE_VIRTUAL_CD, nfit_uuid[NFIT_SPA_VCD]);
	acpi_str_to_uuid(UUID_PERSISTENT_VIRTUAL_DISK, nfit_uuid[NFIT_SPA_PDISK]);
	acpi_str_to_uuid(UUID_PERSISTENT_VIRTUAL_CD, nfit_uuid[NFIT_SPA_PCD]);
	acpi_str_to_uuid(UUID_NFIT_BUS, nfit_uuid[NFIT_DEV_BUS]);
	acpi_str_to_uuid(UUID_NFIT_DIMM, nfit_uuid[NFIT_DEV_DIMM]);

	return acpi_bus_register_driver(&acpi_nfit_driver);
}

static __exit void nfit_exit(void)
{
	acpi_bus_unregister_driver(&acpi_nfit_driver);
}

module_init(nfit_init);
module_exit(nfit_exit);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Intel Corporation");