linux-libre/drivers/acpi/nfit/core.c

/*
 * 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/sysfs.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 <linux/nd.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");

static unsigned int scrub_timeout = NFIT_ARS_TIMEOUT;
module_param(scrub_timeout, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(scrub_timeout, "Initial scrub timeout in seconds");

/* after three payloads of overflow, it's dead jim */
static unsigned int scrub_overflow_abort = 3;
module_param(scrub_overflow_abort, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(scrub_overflow_abort,
		"Number of times we overflow ARS results before abort");

static bool disable_vendor_specific;
module_param(disable_vendor_specific, bool, S_IRUGO);
MODULE_PARM_DESC(disable_vendor_specific,
		"Limit commands to the publicly specified set\n");

LIST_HEAD(acpi_descs);
DEFINE_MUTEX(acpi_desc_lock);

static struct workqueue_struct *nfit_wq;

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_bus_status(void *buf, unsigned int cmd, u32 status)
{
	struct nd_cmd_clear_error *clear_err;
	struct nd_cmd_ars_status *ars_status;
	u16 flags;

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

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

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

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

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

		/* No ARS performed for the current boot */
		if (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 (status == NFIT_ARS_STATUS_INTR) {
			if (ars_status->out_length >= 40 && (ars_status->flags
						& NFIT_ARS_F_OVERFLOW))
				return -ENOSPC;
			return 0;
		}

		/* Unknown status */
		if (status >> 16)
			return -EIO;
		return 0;
	case ND_CMD_CLEAR_ERROR:
		clear_err = buf;
		if (status & 0xffff)
			return -EIO;
		if (!clear_err->cleared)
			return -EIO;
		if (clear_err->length > clear_err->cleared)
			return clear_err->cleared;
		return 0;
	default:
		break;
	}

	/* all other non-zero status results in an error */
	if (status)
		return -EIO;
	return 0;
}

static int xlat_status(struct nvdimm *nvdimm, void *buf, unsigned int cmd,
		u32 status)
{
	if (!nvdimm)
		return xlat_bus_status(buf, cmd, status);
	if (status)
		return -EIO;
	return 0;
}

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);
	union acpi_object in_obj, in_buf, *out_obj;
	const struct nd_cmd_desc *desc = NULL;
	struct device *dev = acpi_desc->dev;
	struct nd_cmd_pkg *call_pkg = NULL;
	const char *cmd_name, *dimm_name;
	unsigned long cmd_mask, dsm_mask;
	u32 offset, fw_status = 0;
	acpi_handle handle;
	unsigned int func;
	const u8 *uuid;
	int rc, i;

	func = cmd;
	if (cmd == ND_CMD_CALL) {
		call_pkg = buf;
		func = call_pkg->nd_command;
	}

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

		if (!adev)
			return -ENOTTY;
		if (call_pkg && nfit_mem->family != call_pkg->nd_family)
			return -ENOTTY;

		dimm_name = nvdimm_name(nvdimm);
		cmd_name = nvdimm_cmd_name(cmd);
		cmd_mask = nvdimm_cmd_mask(nvdimm);
		dsm_mask = nfit_mem->dsm_mask;
		desc = nd_cmd_dimm_desc(cmd);
		uuid = to_nfit_uuid(nfit_mem->family);
		handle = adev->handle;
	} else {
		struct acpi_device *adev = to_acpi_dev(acpi_desc);

		cmd_name = nvdimm_bus_cmd_name(cmd);
		cmd_mask = nd_desc->cmd_mask;
		dsm_mask = cmd_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, &cmd_mask) || !test_bit(func, &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 (call_pkg) {
		/* skip over package wrapper */
		in_buf.buffer.pointer = (void *) &call_pkg->nd_payload;
		in_buf.buffer.length = call_pkg->nd_size_in;
	}

	if (IS_ENABLED(CONFIG_ACPI_NFIT_DEBUG)) {
		dev_dbg(dev, "%s:%s cmd: %d: func: %d input length: %d\n",
				__func__, dimm_name, cmd, func,
				in_buf.buffer.length);
		print_hex_dump_debug("nvdimm in  ", DUMP_PREFIX_OFFSET, 4, 4,
			in_buf.buffer.pointer,
			min_t(u32, 256, in_buf.buffer.length), true);
	}

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

	if (call_pkg) {
		call_pkg->nd_fw_size = out_obj->buffer.length;
		memcpy(call_pkg->nd_payload + call_pkg->nd_size_in,
			out_obj->buffer.pointer,
			min(call_pkg->nd_fw_size, call_pkg->nd_size_out));

		ACPI_FREE(out_obj);
		/*
		 * Need to support FW function w/o known size in advance.
		 * Caller can determine required size based upon nd_fw_size.
		 * If we return an error (like elsewhere) then caller wouldn't
		 * be able to rely upon data returned to make calculation.
		 */
		return 0;
	}

	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,
				out_obj->buffer.length - offset);

		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;
	}

	/*
	 * Set fw_status for all the commands with a known format to be
	 * later interpreted by xlat_status().
	 */
	if (i >= 1 && ((cmd >= ND_CMD_ARS_CAP && cmd <= ND_CMD_CLEAR_ERROR)
			|| (cmd >= ND_CMD_SMART && cmd <= ND_CMD_VENDOR)))
		fw_status = *(u32 *) out_obj->buffer.pointer;

	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(nvdimm, buf, cmd,
						fw_status);
		} 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;
		if (cmd_rc)
			*cmd_rc = xlat_status(nvdimm, buf, cmd, fw_status);
	}

 out:
	ACPI_FREE(out_obj);

	return rc;
}
EXPORT_SYMBOL_GPL(acpi_nfit_ctl);

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];
}

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)
{
	struct device *dev = acpi_desc->dev;
	struct nfit_spa *nfit_spa;

	if (spa->header.length != sizeof(*spa))
		return false;

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

	nfit_spa = devm_kzalloc(dev, sizeof(*nfit_spa) + sizeof(*spa),
			GFP_KERNEL);
	if (!nfit_spa)
		return false;
	INIT_LIST_HEAD(&nfit_spa->list);
	memcpy(nfit_spa->spa, spa, sizeof(*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)
{
	struct device *dev = acpi_desc->dev;
	struct nfit_memdev *nfit_memdev;

	if (memdev->header.length != sizeof(*memdev))
		return false;

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

	nfit_memdev = devm_kzalloc(dev, sizeof(*nfit_memdev) + sizeof(*memdev),
			GFP_KERNEL);
	if (!nfit_memdev)
		return false;
	INIT_LIST_HEAD(&nfit_memdev->list);
	memcpy(nfit_memdev->memdev, memdev, sizeof(*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;
}

/*
 * An implementation may provide a truncated control region if no block windows
 * are defined.
 */
static size_t sizeof_dcr(struct acpi_nfit_control_region *dcr)
{
	if (dcr->header.length < offsetof(struct acpi_nfit_control_region,
				window_size))
		return 0;
	if (dcr->windows)
		return sizeof(*dcr);
	return offsetof(struct acpi_nfit_control_region, window_size);
}

static bool add_dcr(struct acpi_nfit_desc *acpi_desc,
		struct nfit_table_prev *prev,
		struct acpi_nfit_control_region *dcr)
{
	struct device *dev = acpi_desc->dev;
	struct nfit_dcr *nfit_dcr;

	if (!sizeof_dcr(dcr))
		return false;

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

	nfit_dcr = devm_kzalloc(dev, sizeof(*nfit_dcr) + sizeof(*dcr),
			GFP_KERNEL);
	if (!nfit_dcr)
		return false;
	INIT_LIST_HEAD(&nfit_dcr->list);
	memcpy(nfit_dcr->dcr, dcr, sizeof_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)
{
	struct device *dev = acpi_desc->dev;
	struct nfit_bdw *nfit_bdw;

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

	nfit_bdw = devm_kzalloc(dev, sizeof(*nfit_bdw) + sizeof(*bdw),
			GFP_KERNEL);
	if (!nfit_bdw)
		return false;
	INIT_LIST_HEAD(&nfit_bdw->list);
	memcpy(nfit_bdw->bdw, bdw, sizeof(*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 size_t sizeof_idt(struct acpi_nfit_interleave *idt)
{
	if (idt->header.length < sizeof(*idt))
		return 0;
	return sizeof(*idt) + sizeof(u32) * (idt->line_count - 1);
}

static bool add_idt(struct acpi_nfit_desc *acpi_desc,
		struct nfit_table_prev *prev,
		struct acpi_nfit_interleave *idt)
{
	struct device *dev = acpi_desc->dev;
	struct nfit_idt *nfit_idt;

	if (!sizeof_idt(idt))
		return false;

	list_for_each_entry(nfit_idt, &prev->idts, list) {
		if (sizeof_idt(nfit_idt->idt) != sizeof_idt(idt))
			continue;

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

	nfit_idt = devm_kzalloc(dev, sizeof(*nfit_idt) + sizeof_idt(idt),
			GFP_KERNEL);
	if (!nfit_idt)
		return false;
	INIT_LIST_HEAD(&nfit_idt->list);
	memcpy(nfit_idt->idt, idt, sizeof_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 size_t sizeof_flush(struct acpi_nfit_flush_address *flush)
{
	if (flush->header.length < sizeof(*flush))
		return 0;
	return sizeof(*flush) + sizeof(u64) * (flush->hint_count - 1);
}

static bool add_flush(struct acpi_nfit_desc *acpi_desc,
		struct nfit_table_prev *prev,
		struct acpi_nfit_flush_address *flush)
{
	struct device *dev = acpi_desc->dev;
	struct nfit_flush *nfit_flush;

	if (!sizeof_flush(flush))
		return false;

	list_for_each_entry(nfit_flush, &prev->flushes, list) {
		if (sizeof_flush(nfit_flush->flush) != sizeof_flush(flush))
			continue;

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

	nfit_flush = devm_kzalloc(dev, sizeof(*nfit_flush)
			+ sizeof_flush(flush), GFP_KERNEL);
	if (!nfit_flush)
		return false;
	INIT_LIST_HEAD(&nfit_flush->list);
	memcpy(nfit_flush->flush, flush, sizeof_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_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;
		}
		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_flush *nfit_flush;
		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);
			nfit_mem->acpi_desc = acpi_desc;
			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;
		}

		list_for_each_entry(nfit_flush, &acpi_desc->flushes, list) {
			struct acpi_nfit_flush_address *flush;
			u16 i;

			if (nfit_flush->flush->device_handle != device_handle)
				continue;
			nfit_mem->nfit_flush = nfit_flush;
			flush = nfit_flush->flush;
			nfit_mem->flush_wpq = devm_kzalloc(acpi_desc->dev,
					flush->hint_count
					* sizeof(struct resource), GFP_KERNEL);
			if (!nfit_mem->flush_wpq)
				return -ENOMEM;
			for (i = 0; i < flush->hint_count; i++) {
				struct resource *res = &nfit_mem->flush_wpq[i];

				res->start = flush->hint_address[i];
				res->end = res->start + 8 - 1;
			}
			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 ssize_t hw_error_scrub_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->scrub_mode);
}

/*
 * The 'hw_error_scrub' attribute can have the following values written to it:
 * '0': Switch to the default mode where an exception will only insert
 *      the address of the memory error into the poison and badblocks lists.
 * '1': Enable a full scrub to happen if an exception for a memory error is
 *      received.
 */
static ssize_t hw_error_scrub_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t size)
{
	struct nvdimm_bus_descriptor *nd_desc;
	ssize_t rc;
	long val;

	rc = kstrtol(buf, 0, &val);
	if (rc)
		return rc;

	device_lock(dev);
	nd_desc = dev_get_drvdata(dev);
	if (nd_desc) {
		struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);

		switch (val) {
		case HW_ERROR_SCRUB_ON:
			acpi_desc->scrub_mode = HW_ERROR_SCRUB_ON;
			break;
		case HW_ERROR_SCRUB_OFF:
			acpi_desc->scrub_mode = HW_ERROR_SCRUB_OFF;
			break;
		default:
			rc = -EINVAL;
			break;
		}
	}
	device_unlock(dev);
	if (rc)
		return rc;
	return size;
}
static DEVICE_ATTR_RW(hw_error_scrub);

/*
 * This shows the number of full Address Range Scrubs that have been
 * completed since driver load time. Userspace can wait on this using
 * select/poll etc. A '+' at the end indicates an ARS is in progress
 */
static ssize_t scrub_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct nvdimm_bus_descriptor *nd_desc;
	ssize_t rc = -ENXIO;

	device_lock(dev);
	nd_desc = dev_get_drvdata(dev);
	if (nd_desc) {
		struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);

		mutex_lock(&acpi_desc->init_mutex);
		rc = sprintf(buf, "%d%s", acpi_desc->scrub_count,
				work_busy(&acpi_desc->work)
				&& !acpi_desc->cancel ? "+\n" : "\n");
		mutex_unlock(&acpi_desc->init_mutex);
	}
	device_unlock(dev);
	return rc;
}

static ssize_t scrub_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t size)
{
	struct nvdimm_bus_descriptor *nd_desc;
	ssize_t rc;
	long val;

	rc = kstrtol(buf, 0, &val);
	if (rc)
		return rc;
	if (val != 1)
		return -EINVAL;

	device_lock(dev);
	nd_desc = dev_get_drvdata(dev);
	if (nd_desc) {
		struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);

		rc = acpi_nfit_ars_rescan(acpi_desc);
	}
	device_unlock(dev);
	if (rc)
		return rc;
	return size;
}
static DEVICE_ATTR_RW(scrub);

static bool ars_supported(struct nvdimm_bus *nvdimm_bus)
{
	struct nvdimm_bus_descriptor *nd_desc = to_nd_desc(nvdimm_bus);
	const unsigned long mask = 1 << ND_CMD_ARS_CAP | 1 << ND_CMD_ARS_START
		| 1 << ND_CMD_ARS_STATUS;

	return (nd_desc->cmd_mask & mask) == mask;
}

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

	if (a == &dev_attr_scrub.attr && !ars_supported(nvdimm_bus))
		return 0;
	return a->mode;
}

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

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

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, "0x%04x\n", be16_to_cpu(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, "0x%04x\n", be16_to_cpu(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, "0x%04x\n", be16_to_cpu(dcr->device_id));
}
static DEVICE_ATTR_RO(device);

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

	return sprintf(buf, "0x%04x\n", be16_to_cpu(dcr->subsystem_vendor_id));
}
static DEVICE_ATTR_RO(subsystem_vendor);

static ssize_t subsystem_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, "0x%04x\n",
			be16_to_cpu(dcr->subsystem_revision_id));
}
static DEVICE_ATTR_RO(subsystem_rev_id);

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

	return sprintf(buf, "0x%04x\n", be16_to_cpu(dcr->subsystem_device_id));
}
static DEVICE_ATTR_RO(subsystem_device);

static int num_nvdimm_formats(struct nvdimm *nvdimm)
{
	struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm);
	int formats = 0;

	if (nfit_mem->memdev_pmem)
		formats++;
	if (nfit_mem->memdev_bdw)
		formats++;
	return formats;
}

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, "0x%04x\n", le16_to_cpu(dcr->code));
}
static DEVICE_ATTR_RO(format);

static ssize_t format1_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	u32 handle;
	ssize_t rc = -ENXIO;
	struct nfit_mem *nfit_mem;
	struct nfit_memdev *nfit_memdev;
	struct acpi_nfit_desc *acpi_desc;
	struct nvdimm *nvdimm = to_nvdimm(dev);
	struct acpi_nfit_control_region *dcr = to_nfit_dcr(dev);

	nfit_mem = nvdimm_provider_data(nvdimm);
	acpi_desc = nfit_mem->acpi_desc;
	handle = to_nfit_memdev(dev)->device_handle;

	/* assumes DIMMs have at most 2 published interface codes */
	mutex_lock(&acpi_desc->init_mutex);
	list_for_each_entry(nfit_memdev, &acpi_desc->memdevs, list) {
		struct acpi_nfit_memory_map *memdev = nfit_memdev->memdev;
		struct nfit_dcr *nfit_dcr;

		if (memdev->device_handle != handle)
			continue;

		list_for_each_entry(nfit_dcr, &acpi_desc->dcrs, list) {
			if (nfit_dcr->dcr->region_index != memdev->region_index)
				continue;
			if (nfit_dcr->dcr->code == dcr->code)
				continue;
			rc = sprintf(buf, "0x%04x\n",
					le16_to_cpu(nfit_dcr->dcr->code));
			break;
		}
		if (rc != ENXIO)
			break;
	}
	mutex_unlock(&acpi_desc->init_mutex);
	return rc;
}
static DEVICE_ATTR_RO(format1);

static ssize_t formats_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct nvdimm *nvdimm = to_nvdimm(dev);

	return sprintf(buf, "%d\n", num_nvdimm_formats(nvdimm));
}
static DEVICE_ATTR_RO(formats);

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, "0x%08x\n", be32_to_cpu(dcr->serial_number));
}
static DEVICE_ATTR_RO(serial);

static ssize_t family_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct nvdimm *nvdimm = to_nvdimm(dev);
	struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm);

	if (nfit_mem->family < 0)
		return -ENXIO;
	return sprintf(buf, "%d\n", nfit_mem->family);
}
static DEVICE_ATTR_RO(family);

static ssize_t dsm_mask_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct nvdimm *nvdimm = to_nvdimm(dev);
	struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm);

	if (nfit_mem->family < 0)
		return -ENXIO;
	return sprintf(buf, "%#lx\n", nfit_mem->dsm_mask);
}
static DEVICE_ATTR_RO(dsm_mask);

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

	if (dcr->valid_fields & ACPI_NFIT_CONTROL_MFG_INFO_VALID)
		return sprintf(buf, "%04x-%02x-%04x-%08x\n",
				be16_to_cpu(dcr->vendor_id),
				dcr->manufacturing_location,
				be16_to_cpu(dcr->manufacturing_date),
				be32_to_cpu(dcr->serial_number));
	else
		return sprintf(buf, "%04x-%08x\n",
				be16_to_cpu(dcr->vendor_id),
				be32_to_cpu(dcr->serial_number));
}
static DEVICE_ATTR_RO(id);

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_rev_id.attr,
	&dev_attr_subsystem_vendor.attr,
	&dev_attr_subsystem_device.attr,
	&dev_attr_subsystem_rev_id.attr,
	&dev_attr_format.attr,
	&dev_attr_formats.attr,
	&dev_attr_format1.attr,
	&dev_attr_serial.attr,
	&dev_attr_flags.attr,
	&dev_attr_id.attr,
	&dev_attr_family.attr,
	&dev_attr_dsm_mask.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);
	struct nvdimm *nvdimm = to_nvdimm(dev);

	if (!to_nfit_dcr(dev))
		return 0;
	if (a == &dev_attr_format1.attr && num_nvdimm_formats(nvdimm) <= 1)
		return 0;
	return a->mode;
}

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;
}

void __acpi_nvdimm_notify(struct device *dev, u32 event)
{
	struct nfit_mem *nfit_mem;
	struct acpi_nfit_desc *acpi_desc;

	dev_dbg(dev->parent, "%s: %s: event: %d\n", dev_name(dev), __func__,
			event);

	if (event != NFIT_NOTIFY_DIMM_HEALTH) {
		dev_dbg(dev->parent, "%s: unknown event: %d\n", dev_name(dev),
				event);
		return;
	}

	acpi_desc = dev_get_drvdata(dev->parent);
	if (!acpi_desc)
		return;

	/*
	 * If we successfully retrieved acpi_desc, then we know nfit_mem data
	 * is still valid.
	 */
	nfit_mem = dev_get_drvdata(dev);
	if (nfit_mem && nfit_mem->flags_attr)
		sysfs_notify_dirent(nfit_mem->flags_attr);
}
EXPORT_SYMBOL_GPL(__acpi_nvdimm_notify);

static void acpi_nvdimm_notify(acpi_handle handle, u32 event, void *data)
{
	struct acpi_device *adev = data;
	struct device *dev = &adev->dev;

	device_lock(dev->parent);
	__acpi_nvdimm_notify(dev, event);
	device_unlock(dev->parent);
}

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;
	unsigned long dsm_mask;
	const u8 *uuid;
	int i;

	/* nfit test assumes 1:1 relationship between commands and dsms */
	nfit_mem->dsm_mask = acpi_desc->dimm_cmd_force_en;
	nfit_mem->family = NVDIMM_FAMILY_INTEL;
	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;
	}

	if (ACPI_FAILURE(acpi_install_notify_handler(adev_dimm->handle,
		ACPI_DEVICE_NOTIFY, acpi_nvdimm_notify, adev_dimm))) {
		dev_err(dev, "%s: notification registration failed\n",
				dev_name(&adev_dimm->dev));
		return -ENXIO;
	}
	/*
	 * Record nfit_mem for the notification path to track back to
	 * the nfit sysfs attributes for this dimm device object.
	 */
	dev_set_drvdata(&adev_dimm->dev, nfit_mem);

	/*
	 * Until standardization materializes we need to consider 4
	 * different command sets.  Note, that checking for function0 (bit0)
	 * tells us if any commands are reachable through this uuid.
	 */
	for (i = NVDIMM_FAMILY_INTEL; i <= NVDIMM_FAMILY_MSFT; i++)
		if (acpi_check_dsm(adev_dimm->handle, to_nfit_uuid(i), 1, 1))
			break;

	/* limit the supported commands to those that are publicly documented */
	nfit_mem->family = i;
	if (nfit_mem->family == NVDIMM_FAMILY_INTEL) {
		dsm_mask = 0x3fe;
		if (disable_vendor_specific)
			dsm_mask &= ~(1 << ND_CMD_VENDOR);
	} else if (nfit_mem->family == NVDIMM_FAMILY_HPE1) {
		dsm_mask = 0x1c3c76;
	} else if (nfit_mem->family == NVDIMM_FAMILY_HPE2) {
		dsm_mask = 0x1fe;
		if (disable_vendor_specific)
			dsm_mask &= ~(1 << 8);
	} else if (nfit_mem->family == NVDIMM_FAMILY_MSFT) {
		dsm_mask = 0xffffffff;
	} else {
		dev_dbg(dev, "unknown dimm command family\n");
		nfit_mem->family = -1;
		/* DSMs are optional, continue loading the driver... */
		return 0;
	}

	uuid = to_nfit_uuid(nfit_mem->family);
	for_each_set_bit(i, &dsm_mask, BITS_PER_LONG)
		if (acpi_check_dsm(adev_dimm->handle, uuid, 1, 1ULL << i))
			set_bit(i, &nfit_mem->dsm_mask);

	return 0;
}

static void shutdown_dimm_notify(void *data)
{
	struct acpi_nfit_desc *acpi_desc = data;
	struct nfit_mem *nfit_mem;

	mutex_lock(&acpi_desc->init_mutex);
	/*
	 * Clear out the nfit_mem->flags_attr and shut down dimm event
	 * notifications.
	 */
	list_for_each_entry(nfit_mem, &acpi_desc->dimms, list) {
		struct acpi_device *adev_dimm = nfit_mem->adev;

		if (nfit_mem->flags_attr) {
			sysfs_put(nfit_mem->flags_attr);
			nfit_mem->flags_attr = NULL;
		}
		if (adev_dimm) {
			acpi_remove_notify_handler(adev_dimm->handle,
					ACPI_DEVICE_NOTIFY, acpi_nvdimm_notify);
			dev_set_drvdata(&adev_dimm->dev, NULL);
		}
	}
	mutex_unlock(&acpi_desc->init_mutex);
}

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

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

		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;

		/*
		 * TODO: provide translation for non-NVDIMM_FAMILY_INTEL
		 * devices (i.e. from nd_cmd to acpi_dsm) to standardize the
		 * userspace interface.
		 */
		cmd_mask = 1UL << ND_CMD_CALL;
		if (nfit_mem->family == NVDIMM_FAMILY_INTEL)
			cmd_mask |= nfit_mem->dsm_mask;

		flush = nfit_mem->nfit_flush ? nfit_mem->nfit_flush->flush
			: NULL;
		nvdimm = nvdimm_create(acpi_desc->nvdimm_bus, nfit_mem,
				acpi_nfit_dimm_attribute_groups,
				flags, cmd_mask, flush ? flush->hint_count : 0,
				nfit_mem->flush_wpq);
		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" : "");

	}

	rc = nvdimm_bus_check_dimm_count(acpi_desc->nvdimm_bus, dimm_count);
	if (rc)
		return rc;

	/*
	 * Now that dimms are successfully registered, and async registration
	 * is flushed, attempt to enable event notification.
	 */
	list_for_each_entry(nfit_mem, &acpi_desc->dimms, list) {
		struct kernfs_node *nfit_kernfs;

		nvdimm = nfit_mem->nvdimm;
		if (!nvdimm)
			continue;

		nfit_kernfs = sysfs_get_dirent(nvdimm_kobj(nvdimm)->sd, "nfit");
		if (nfit_kernfs)
			nfit_mem->flags_attr = sysfs_get_dirent(nfit_kernfs,
					"flags");
		sysfs_put(nfit_kernfs);
		if (!nfit_mem->flags_attr)
			dev_warn(acpi_desc->dev, "%s: notifications disabled\n",
					nvdimm_name(nvdimm));
	}

	return devm_add_action_or_reset(acpi_desc->dev, shutdown_dimm_notify,
			acpi_desc);
}

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->cmd_mask = acpi_desc->bus_cmd_force_en;
	adev = to_acpi_dev(acpi_desc);
	if (!adev)
		return;

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

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;

	if (map0->region_offset < map1->region_offset)
		return -1;
	else if (map0->region_offset > map1->region_offset)
		return 1;
	return 0;
}

/* 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_desc *mapping = &ndr_desc->mapping[i];
		struct nfit_set_info_map *map = &info->mapping[i];
		struct nvdimm *nvdimm = 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);

	/* support namespaces created with the wrong sort order */
	sort(&info->mapping[0], nr, sizeof(struct nfit_set_info_map),
			cmp_map_compat, NULL);
	nd_set->altcookie = 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 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;
	const u32 STATUS_MASK = 0x80000037;

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

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

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);
	nvdimm_flush(nfit_blk->nd_region);

	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)
		nvdimm_flush(nfit_blk->nd_region);

	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 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 nd_blk_region *ndbr = to_nd_blk_region(dev);
	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 = devm_nvdimm_memremap(dev, nfit_mem->spa_bdw->address,
                        nfit_mem->spa_bdw->length, ARCH_MEMREMAP_PMEM);
	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 = devm_nvdimm_ioremap(dev, nfit_mem->spa_dcr->address,
			nfit_mem->spa_dcr->length);
	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;
	}

	if (nvdimm_has_flush(nfit_blk->nd_region) < 0)
		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 int ars_get_cap(struct acpi_nfit_desc *acpi_desc,
		struct nd_cmd_ars_cap *cmd, struct nfit_spa *nfit_spa)
{
	struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc;
	struct acpi_nfit_system_address *spa = nfit_spa->spa;
	int cmd_rc, rc;

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

static int ars_start(struct acpi_nfit_desc *acpi_desc, struct nfit_spa *nfit_spa)
{
	int rc;
	int cmd_rc;
	struct nd_cmd_ars_start ars_start;
	struct acpi_nfit_system_address *spa = nfit_spa->spa;
	struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc;

	memset(&ars_start, 0, sizeof(ars_start));
	ars_start.address = spa->address;
	ars_start.length = spa->length;
	if (nfit_spa_type(spa) == NFIT_SPA_PM)
		ars_start.type = ND_ARS_PERSISTENT;
	else if (nfit_spa_type(spa) == NFIT_SPA_VOLATILE)
		ars_start.type = ND_ARS_VOLATILE;
	else
		return -ENOTTY;

	rc = nd_desc->ndctl(nd_desc, NULL, ND_CMD_ARS_START, &ars_start,
			sizeof(ars_start), &cmd_rc);

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

static int ars_continue(struct acpi_nfit_desc *acpi_desc)
{
	int rc, cmd_rc;
	struct nd_cmd_ars_start ars_start;
	struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc;
	struct nd_cmd_ars_status *ars_status = acpi_desc->ars_status;

	memset(&ars_start, 0, sizeof(ars_start));
	ars_start.address = ars_status->restart_address;
	ars_start.length = ars_status->restart_length;
	ars_start.type = ars_status->type;
	rc = nd_desc->ndctl(nd_desc, NULL, ND_CMD_ARS_START, &ars_start,
			sizeof(ars_start), &cmd_rc);
	if (rc < 0)
		return rc;
	return cmd_rc;
}

static int ars_get_status(struct acpi_nfit_desc *acpi_desc)
{
	struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc;
	struct nd_cmd_ars_status *ars_status = acpi_desc->ars_status;
	int rc, cmd_rc;

	rc = nd_desc->ndctl(nd_desc, NULL, ND_CMD_ARS_STATUS, ars_status,
			acpi_desc->ars_status_size, &cmd_rc);
	if (rc < 0)
		return rc;
	return cmd_rc;
}

static int ars_status_process_records(struct acpi_nfit_desc *acpi_desc,
		struct nd_cmd_ars_status *ars_status)
{
	struct nvdimm_bus *nvdimm_bus = acpi_desc->nvdimm_bus;
	int rc;
	u32 i;

	/*
	 * First record starts at 44 byte offset from the start of the
	 * payload.
	 */
	if (ars_status->out_length < 44)
		return 0;
	for (i = 0; i < ars_status->num_records; i++) {
		/* only process full records */
		if (ars_status->out_length
				< 44 + sizeof(struct nd_ars_record) * (i + 1))
			break;
		rc = nvdimm_bus_add_poison(nvdimm_bus,
				ars_status->records[i].err_address,
				ars_status->records[i].length);
		if (rc)
			return rc;
	}
	if (i < ars_status->num_records)
		dev_warn(acpi_desc->dev, "detected truncated ars results\n");

	return 0;
}

static void acpi_nfit_remove_resource(void *data)
{
	struct resource *res = data;

	remove_resource(res);
}

static int acpi_nfit_insert_resource(struct acpi_nfit_desc *acpi_desc,
		struct nd_region_desc *ndr_desc)
{
	struct resource *res, *nd_res = ndr_desc->res;
	int is_pmem, ret;

	/* No operation if the region is already registered as PMEM */
	is_pmem = region_intersects(nd_res->start, resource_size(nd_res),
				IORESOURCE_MEM, IORES_DESC_PERSISTENT_MEMORY);
	if (is_pmem == REGION_INTERSECTS)
		return 0;

	res = devm_kzalloc(acpi_desc->dev, sizeof(*res), GFP_KERNEL);
	if (!res)
		return -ENOMEM;

	res->name = "Persistent Memory";
	res->start = nd_res->start;
	res->end = nd_res->end;
	res->flags = IORESOURCE_MEM;
	res->desc = IORES_DESC_PERSISTENT_MEMORY;

	ret = insert_resource(&iomem_resource, res);
	if (ret)
		return ret;

	ret = devm_add_action_or_reset(acpi_desc->dev,
					acpi_nfit_remove_resource,
					res);
	if (ret)
		return ret;

	return 0;
}

static int acpi_nfit_init_mapping(struct acpi_nfit_desc *acpi_desc,
		struct nd_mapping_desc *mapping, struct nd_region_desc *ndr_desc,
		struct acpi_nfit_memory_map *memdev,
		struct nfit_spa *nfit_spa)
{
	struct nvdimm *nvdimm = acpi_nfit_dimm_by_handle(acpi_desc,
			memdev->device_handle);
	struct acpi_nfit_system_address *spa = nfit_spa->spa;
	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;
	}

	mapping->nvdimm = nvdimm;
	switch (nfit_spa_type(spa)) {
	case NFIT_SPA_PM:
	case NFIT_SPA_VOLATILE:
		mapping->start = memdev->address;
		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 {
			mapping->size = nfit_mem->bdw->capacity;
			mapping->start = nfit_mem->bdw->start_address;
			ndr_desc->num_lanes = nfit_mem->bdw->windows;
			blk_valid = 1;
		}

		ndr_desc->mapping = 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->do_io = acpi_desc->blk_do_io;
		nfit_spa->nd_region = nvdimm_blk_region_create(acpi_desc->nvdimm_bus,
				ndr_desc);
		if (!nfit_spa->nd_region)
			return -ENOMEM;
		break;
	}

	return 0;
}

static bool nfit_spa_is_virtual(struct acpi_nfit_system_address *spa)
{
	return (nfit_spa_type(spa) == NFIT_SPA_VDISK ||
		nfit_spa_type(spa) == NFIT_SPA_VCD   ||
		nfit_spa_type(spa) == NFIT_SPA_PDISK ||
		nfit_spa_type(spa) == NFIT_SPA_PCD);
}

static int acpi_nfit_register_region(struct acpi_nfit_desc *acpi_desc,
		struct nfit_spa *nfit_spa)
{
	static struct nd_mapping_desc 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->nd_region)
		return 0;

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

	memset(&res, 0, sizeof(res));
	memset(&mappings, 0, sizeof(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_desc *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;
		}
		mapping = &mappings[count++];
		rc = acpi_nfit_init_mapping(acpi_desc, mapping, ndr_desc,
				memdev, nfit_spa);
		if (rc)
			goto out;
	}

	ndr_desc->mapping = mappings;
	ndr_desc->num_mappings = count;
	rc = acpi_nfit_init_interleave_set(acpi_desc, ndr_desc, spa);
	if (rc)
		goto out;

	nvdimm_bus = acpi_desc->nvdimm_bus;
	if (nfit_spa_type(spa) == NFIT_SPA_PM) {
		rc = acpi_nfit_insert_resource(acpi_desc, ndr_desc);
		if (rc) {
			dev_warn(acpi_desc->dev,
				"failed to insert pmem resource to iomem: %d\n",
				rc);
			goto out;
		}

		nfit_spa->nd_region = nvdimm_pmem_region_create(nvdimm_bus,
				ndr_desc);
		if (!nfit_spa->nd_region)
			rc = -ENOMEM;
	} else if (nfit_spa_type(spa) == NFIT_SPA_VOLATILE) {
		nfit_spa->nd_region = nvdimm_volatile_region_create(nvdimm_bus,
				ndr_desc);
		if (!nfit_spa->nd_region)
			rc = -ENOMEM;
	} else if (nfit_spa_is_virtual(spa)) {
		nfit_spa->nd_region = nvdimm_pmem_region_create(nvdimm_bus,
				ndr_desc);
		if (!nfit_spa->nd_region)
			rc = -ENOMEM;
	}

 out:
	if (rc)
		dev_err(acpi_desc->dev, "failed to register spa range %d\n",
				nfit_spa->spa->range_index);
	return rc;
}

static int ars_status_alloc(struct acpi_nfit_desc *acpi_desc,
		u32 max_ars)
{
	struct device *dev = acpi_desc->dev;
	struct nd_cmd_ars_status *ars_status;

	if (acpi_desc->ars_status && acpi_desc->ars_status_size >= max_ars) {
		memset(acpi_desc->ars_status, 0, acpi_desc->ars_status_size);
		return 0;
	}

	if (acpi_desc->ars_status)
		devm_kfree(dev, acpi_desc->ars_status);
	acpi_desc->ars_status = NULL;
	ars_status = devm_kzalloc(dev, max_ars, GFP_KERNEL);
	if (!ars_status)
		return -ENOMEM;
	acpi_desc->ars_status = ars_status;
	acpi_desc->ars_status_size = max_ars;
	return 0;
}

static int acpi_nfit_query_poison(struct acpi_nfit_desc *acpi_desc,
		struct nfit_spa *nfit_spa)
{
	struct acpi_nfit_system_address *spa = nfit_spa->spa;
	int rc;

	if (!nfit_spa->max_ars) {
		struct nd_cmd_ars_cap ars_cap;

		memset(&ars_cap, 0, sizeof(ars_cap));
		rc = ars_get_cap(acpi_desc, &ars_cap, nfit_spa);
		if (rc < 0)
			return rc;
		nfit_spa->max_ars = ars_cap.max_ars_out;
		nfit_spa->clear_err_unit = ars_cap.clear_err_unit;
		/* check that the supported scrub types match the spa type */
		if (nfit_spa_type(spa) == NFIT_SPA_VOLATILE &&
				((ars_cap.status >> 16) & ND_ARS_VOLATILE) == 0)
			return -ENOTTY;
		else if (nfit_spa_type(spa) == NFIT_SPA_PM &&
				((ars_cap.status >> 16) & ND_ARS_PERSISTENT) == 0)
			return -ENOTTY;
	}

	if (ars_status_alloc(acpi_desc, nfit_spa->max_ars))
		return -ENOMEM;

	rc = ars_get_status(acpi_desc);
	if (rc < 0 && rc != -ENOSPC)
		return rc;

	if (ars_status_process_records(acpi_desc, acpi_desc->ars_status))
		return -ENOMEM;

	return 0;
}

static void acpi_nfit_async_scrub(struct acpi_nfit_desc *acpi_desc,
		struct nfit_spa *nfit_spa)
{
	struct acpi_nfit_system_address *spa = nfit_spa->spa;
	unsigned int overflow_retry = scrub_overflow_abort;
	u64 init_ars_start = 0, init_ars_len = 0;
	struct device *dev = acpi_desc->dev;
	unsigned int tmo = scrub_timeout;
	int rc;

	if (!nfit_spa->ars_required || !nfit_spa->nd_region)
		return;

	rc = ars_start(acpi_desc, nfit_spa);
	/*
	 * If we timed out the initial scan we'll still be busy here,
	 * and will wait another timeout before giving up permanently.
	 */
	if (rc < 0 && rc != -EBUSY)
		return;

	do {
		u64 ars_start, ars_len;

		if (acpi_desc->cancel)
			break;
		rc = acpi_nfit_query_poison(acpi_desc, nfit_spa);
		if (rc == -ENOTTY)
			break;
		if (rc == -EBUSY && !tmo) {
			dev_warn(dev, "range %d ars timeout, aborting\n",
					spa->range_index);
			break;
		}

		if (rc == -EBUSY) {
			/*
			 * Note, entries may be appended to the list
			 * while the lock is dropped, but the workqueue
			 * being active prevents entries being deleted /
			 * freed.
			 */
			mutex_unlock(&acpi_desc->init_mutex);
			ssleep(1);
			tmo--;
			mutex_lock(&acpi_desc->init_mutex);
			continue;
		}

		/* we got some results, but there are more pending... */
		if (rc == -ENOSPC && overflow_retry--) {
			if (!init_ars_len) {
				init_ars_len = acpi_desc->ars_status->length;
				init_ars_start = acpi_desc->ars_status->address;
			}
			rc = ars_continue(acpi_desc);
		}

		if (rc < 0) {
			dev_warn(dev, "range %d ars continuation failed\n",
					spa->range_index);
			break;
		}

		if (init_ars_len) {
			ars_start = init_ars_start;
			ars_len = init_ars_len;
		} else {
			ars_start = acpi_desc->ars_status->address;
			ars_len = acpi_desc->ars_status->length;
		}
		dev_dbg(dev, "spa range: %d ars from %#llx + %#llx complete\n",
				spa->range_index, ars_start, ars_len);
		/* notify the region about new poison entries */
		nvdimm_region_notify(nfit_spa->nd_region,
				NVDIMM_REVALIDATE_POISON);
		break;
	} while (1);
}

static void acpi_nfit_scrub(struct work_struct *work)
{
	struct device *dev;
	u64 init_scrub_length = 0;
	struct nfit_spa *nfit_spa;
	u64 init_scrub_address = 0;
	bool init_ars_done = false;
	struct acpi_nfit_desc *acpi_desc;
	unsigned int tmo = scrub_timeout;
	unsigned int overflow_retry = scrub_overflow_abort;

	acpi_desc = container_of(work, typeof(*acpi_desc), work);
	dev = acpi_desc->dev;

	/*
	 * We scrub in 2 phases.  The first phase waits for any platform
	 * firmware initiated scrubs to complete and then we go search for the
	 * affected spa regions to mark them scanned.  In the second phase we
	 * initiate a directed scrub for every range that was not scrubbed in
	 * phase 1. If we're called for a 'rescan', we harmlessly pass through
	 * the first phase, but really only care about running phase 2, where
	 * regions can be notified of new poison.
	 */

	/* process platform firmware initiated scrubs */
 retry:
	mutex_lock(&acpi_desc->init_mutex);
	list_for_each_entry(nfit_spa, &acpi_desc->spas, list) {
		struct nd_cmd_ars_status *ars_status;
		struct acpi_nfit_system_address *spa;
		u64 ars_start, ars_len;
		int rc;

		if (acpi_desc->cancel)
			break;

		if (nfit_spa->nd_region)
			continue;

		if (init_ars_done) {
			/*
			 * No need to re-query, we're now just
			 * reconciling all the ranges covered by the
			 * initial scrub
			 */
			rc = 0;
		} else
			rc = acpi_nfit_query_poison(acpi_desc, nfit_spa);

		if (rc == -ENOTTY) {
			/* no ars capability, just register spa and move on */
			acpi_nfit_register_region(acpi_desc, nfit_spa);
			continue;
		}

		if (rc == -EBUSY && !tmo) {
			/* fallthrough to directed scrub in phase 2 */
			dev_warn(dev, "timeout awaiting ars results, continuing...\n");
			break;
		} else if (rc == -EBUSY) {
			mutex_unlock(&acpi_desc->init_mutex);
			ssleep(1);
			tmo--;
			goto retry;
		}

		/* we got some results, but there are more pending... */
		if (rc == -ENOSPC && overflow_retry--) {
			ars_status = acpi_desc->ars_status;
			/*
			 * Record the original scrub range, so that we
			 * can recall all the ranges impacted by the
			 * initial scrub.
			 */
			if (!init_scrub_length) {
				init_scrub_length = ars_status->length;
				init_scrub_address = ars_status->address;
			}
			rc = ars_continue(acpi_desc);
			if (rc == 0) {
				mutex_unlock(&acpi_desc->init_mutex);
				goto retry;
			}
		}

		if (rc < 0) {
			/*
			 * Initial scrub failed, we'll give it one more
			 * try below...
			 */
			break;
		}

		/* We got some final results, record completed ranges */
		ars_status = acpi_desc->ars_status;
		if (init_scrub_length) {
			ars_start = init_scrub_address;
			ars_len = ars_start + init_scrub_length;
		} else {
			ars_start = ars_status->address;
			ars_len = ars_status->length;
		}
		spa = nfit_spa->spa;

		if (!init_ars_done) {
			init_ars_done = true;
			dev_dbg(dev, "init scrub %#llx + %#llx complete\n",
					ars_start, ars_len);
		}
		if (ars_start <= spa->address && ars_start + ars_len
				>= spa->address + spa->length)
			acpi_nfit_register_region(acpi_desc, nfit_spa);
	}

	/*
	 * For all the ranges not covered by an initial scrub we still
	 * want to see if there are errors, but it's ok to discover them
	 * asynchronously.
	 */
	list_for_each_entry(nfit_spa, &acpi_desc->spas, list) {
		/*
		 * Flag all the ranges that still need scrubbing, but
		 * register them now to make data available.
		 */
		if (!nfit_spa->nd_region) {
			nfit_spa->ars_required = 1;
			acpi_nfit_register_region(acpi_desc, nfit_spa);
		}
	}

	list_for_each_entry(nfit_spa, &acpi_desc->spas, list)
		acpi_nfit_async_scrub(acpi_desc, nfit_spa);
	acpi_desc->scrub_count++;
	if (acpi_desc->scrub_count_state)
		sysfs_notify_dirent(acpi_desc->scrub_count_state);
	mutex_unlock(&acpi_desc->init_mutex);
}

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, type = nfit_spa_type(nfit_spa->spa);

		/* PMEM and VMEM will be registered by the ARS workqueue */
		if (type == NFIT_SPA_PM || type == NFIT_SPA_VOLATILE)
			continue;
		/* BLK apertures belong to BLK region registration below */
		if (type == NFIT_SPA_BDW)
			continue;
		/* BLK regions don't need to wait for ARS results */
		rc = acpi_nfit_register_region(acpi_desc, nfit_spa);
		if (rc)
			return rc;
	}

	queue_work(nfit_wq, &acpi_desc->work);
	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;
}

static int acpi_nfit_desc_init_scrub_attr(struct acpi_nfit_desc *acpi_desc)
{
	struct device *dev = acpi_desc->dev;
	struct kernfs_node *nfit;
	struct device *bus_dev;

	if (!ars_supported(acpi_desc->nvdimm_bus))
		return 0;

	bus_dev = to_nvdimm_bus_dev(acpi_desc->nvdimm_bus);
	nfit = sysfs_get_dirent(bus_dev->kobj.sd, "nfit");
	if (!nfit) {
		dev_err(dev, "sysfs_get_dirent 'nfit' failed\n");
		return -ENODEV;
	}
	acpi_desc->scrub_count_state = sysfs_get_dirent(nfit, "scrub");
	sysfs_put(nfit);
	if (!acpi_desc->scrub_count_state) {
		dev_err(dev, "sysfs_get_dirent 'scrub' failed\n");
		return -ENODEV;
	}

	return 0;
}

static void acpi_nfit_destruct(void *data)
{
	struct acpi_nfit_desc *acpi_desc = data;
	struct device *bus_dev = to_nvdimm_bus_dev(acpi_desc->nvdimm_bus);

	/*
	 * Destruct under acpi_desc_lock so that nfit_handle_mce does not
	 * race teardown
	 */
	mutex_lock(&acpi_desc_lock);
	acpi_desc->cancel = 1;
	/*
	 * Bounce the nvdimm bus lock to make sure any in-flight
	 * acpi_nfit_ars_rescan() submissions have had a chance to
	 * either submit or see ->cancel set.
	 */
	device_lock(bus_dev);
	device_unlock(bus_dev);

	flush_workqueue(nfit_wq);
	if (acpi_desc->scrub_count_state)
		sysfs_put(acpi_desc->scrub_count_state);
	nvdimm_bus_unregister(acpi_desc->nvdimm_bus);
	acpi_desc->nvdimm_bus = NULL;
	list_del(&acpi_desc->list);
	mutex_unlock(&acpi_desc_lock);
}

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

	if (!acpi_desc->nvdimm_bus) {
		acpi_nfit_init_dsms(acpi_desc);

		acpi_desc->nvdimm_bus = nvdimm_bus_register(dev,
				&acpi_desc->nd_desc);
		if (!acpi_desc->nvdimm_bus)
			return -ENOMEM;

		rc = devm_add_action_or_reset(dev, acpi_nfit_destruct,
				acpi_desc);
		if (rc)
			return rc;

		rc = acpi_nfit_desc_init_scrub_attr(acpi_desc);
		if (rc)
			return rc;

		/* register this acpi_desc for mce notifications */
		mutex_lock(&acpi_desc_lock);
		list_add_tail(&acpi_desc->list, &acpi_descs);
		mutex_unlock(&acpi_desc_lock);
	}

	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);

	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;

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

	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);

struct acpi_nfit_flush_work {
	struct work_struct work;
	struct completion cmp;
};

static void flush_probe(struct work_struct *work)
{
	struct acpi_nfit_flush_work *flush;

	flush = container_of(work, typeof(*flush), work);
	complete(&flush->cmp);
}

static int acpi_nfit_flush_probe(struct nvdimm_bus_descriptor *nd_desc)
{
	struct acpi_nfit_desc *acpi_desc = to_acpi_nfit_desc(nd_desc);
	struct device *dev = acpi_desc->dev;
	struct acpi_nfit_flush_work flush;
	int rc;

	/* bounce the device lock to flush acpi_nfit_add / acpi_nfit_notify */
	device_lock(dev);
	device_unlock(dev);

	/*
	 * Scrub work could take 10s of seconds, userspace may give up so we
	 * need to be interruptible while waiting.
	 */
	INIT_WORK_ONSTACK(&flush.work, flush_probe);
	COMPLETION_INITIALIZER_ONSTACK(flush.cmp);
	queue_work(nfit_wq, &flush.work);

	rc = wait_for_completion_interruptible(&flush.cmp);
	cancel_work_sync(&flush.work);
	return rc;
}

static int acpi_nfit_clear_to_send(struct nvdimm_bus_descriptor *nd_desc,
		struct nvdimm *nvdimm, unsigned int cmd)
{
	struct acpi_nfit_desc *acpi_desc = to_acpi_nfit_desc(nd_desc);

	if (nvdimm)
		return 0;
	if (cmd != ND_CMD_ARS_START)
		return 0;

	/*
	 * The kernel and userspace may race to initiate a scrub, but
	 * the scrub thread is prepared to lose that initial race.  It
	 * just needs guarantees that any ars it initiates are not
	 * interrupted by any intervening start reqeusts from userspace.
	 */
	if (work_busy(&acpi_desc->work))
		return -EBUSY;

	return 0;
}

int acpi_nfit_ars_rescan(struct acpi_nfit_desc *acpi_desc)
{
	struct device *dev = acpi_desc->dev;
	struct nfit_spa *nfit_spa;

	if (work_busy(&acpi_desc->work))
		return -EBUSY;

	if (acpi_desc->cancel)
		return 0;

	mutex_lock(&acpi_desc->init_mutex);
	list_for_each_entry(nfit_spa, &acpi_desc->spas, list) {
		struct acpi_nfit_system_address *spa = nfit_spa->spa;

		if (nfit_spa_type(spa) != NFIT_SPA_PM)
			continue;

		nfit_spa->ars_required = 1;
	}
	queue_work(nfit_wq, &acpi_desc->work);
	dev_dbg(dev, "%s: ars_scan triggered\n", __func__);
	mutex_unlock(&acpi_desc->init_mutex);

	return 0;
}

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->module = THIS_MODULE;
	nd_desc->ndctl = acpi_nfit_ctl;
	nd_desc->flush_probe = acpi_nfit_flush_probe;
	nd_desc->clear_to_send = acpi_nfit_clear_to_send;
	nd_desc->attr_groups = acpi_nfit_attribute_groups;

	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);
	INIT_LIST_HEAD(&acpi_desc->list);
	mutex_init(&acpi_desc->init_mutex);
	INIT_WORK(&acpi_desc->work, acpi_nfit_scrub);
}
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 = 0;

	status = acpi_get_table_with_size(ACPI_SIG_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);

	/* Save the acpi header for exporting the revision via sysfs */
	acpi_desc->acpi_header = *tbl;

	/* 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 = buf.pointer;

		if (obj->type == ACPI_TYPE_BUFFER)
			rc = acpi_nfit_init(acpi_desc, obj->buffer.pointer,
					obj->buffer.length);
		else
			dev_dbg(dev, "%s invalid type %d, ignoring _FIT\n",
				 __func__, (int) obj->type);
		kfree(buf.pointer);
	} else
		/* skip over the lead-in header table */
		rc = acpi_nfit_init(acpi_desc, (void *) tbl
				+ sizeof(struct acpi_table_nfit),
				sz - sizeof(struct acpi_table_nfit));
	return rc;
}

static int acpi_nfit_remove(struct acpi_device *adev)
{
	/* see acpi_nfit_destruct */
	return 0;
}

void __acpi_nfit_notify(struct device *dev, acpi_handle handle, u32 event)
{
	struct acpi_nfit_desc *acpi_desc = dev_get_drvdata(dev);
	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object *obj;
	acpi_status status;
	int ret;

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

	if (event != NFIT_NOTIFY_UPDATE)
		return;

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

	if (!acpi_desc) {
		acpi_desc = devm_kzalloc(dev, sizeof(*acpi_desc), GFP_KERNEL);
		if (!acpi_desc)
			return;
		acpi_nfit_desc_init(acpi_desc, dev);
	} else {
		/*
		 * Finish previous registration before considering new
		 * regions.
		 */
		flush_workqueue(nfit_wq);
	}

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

	obj = buf.pointer;
	if (obj->type == ACPI_TYPE_BUFFER) {
		ret = acpi_nfit_init(acpi_desc, obj->buffer.pointer,
				obj->buffer.length);
		if (ret)
			dev_err(dev, "failed to merge updated NFIT\n");
	} else
		dev_err(dev, "Invalid _FIT\n");
	kfree(buf.pointer);
}
EXPORT_SYMBOL_GPL(__acpi_nfit_notify);

static void acpi_nfit_notify(struct acpi_device *adev, u32 event)
{
	device_lock(&adev->dev);
	__acpi_nfit_notify(&adev->dev, adev->handle, event);
	device_unlock(&adev->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)
{
	int ret;

	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]);
	acpi_str_to_uuid(UUID_NFIT_DIMM_N_HPE1, nfit_uuid[NFIT_DEV_DIMM_N_HPE1]);
	acpi_str_to_uuid(UUID_NFIT_DIMM_N_HPE2, nfit_uuid[NFIT_DEV_DIMM_N_HPE2]);
	acpi_str_to_uuid(UUID_NFIT_DIMM_N_MSFT, nfit_uuid[NFIT_DEV_DIMM_N_MSFT]);

	nfit_wq = create_singlethread_workqueue("nfit");
	if (!nfit_wq)
		return -ENOMEM;

	nfit_mce_register();
	ret = acpi_bus_register_driver(&acpi_nfit_driver);
	if (ret) {
		nfit_mce_unregister();
		destroy_workqueue(nfit_wq);
	}

	return ret;

}

static __exit void nfit_exit(void)
{
	nfit_mce_unregister();
	acpi_bus_unregister_driver(&acpi_nfit_driver);
	destroy_workqueue(nfit_wq);
	WARN_ON(!list_empty(&acpi_descs));
}

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