/*
 * 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 <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 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_status(void *buf, unsigned int cmd)
{
        struct nd_cmd_clear_error *clear_err;
        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;
        case ND_CMD_CLEAR_ERROR:
                clear_err = buf;
                if (clear_err->status & 0xffff)
                        return -EIO;
                if (!clear_err->cleared)
                        return -EIO;
                if (clear_err->length > clear_err->cleared)
                        return clear_err->cleared;
                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;
                if (cmd_rc)
                        *cmd_rc = xlat_status(buf, cmd);
        }

 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_CLEAR_ERROR; 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, 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 nvdimm_bus *nvdimm_bus,
                struct nd_cmd_ars_status *ars_status)
{
        int rc;
        u32 i;

        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 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(acpi_desc->dev, acpi_nfit_remove_resource, res);
        if (ret) {
                remove_resource(res);
                return ret;
        }

        return 0;
}

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 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;
        }

        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;
                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 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->nd_region)
                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, nfit_spa);
                if (rc)
                        goto out;
        }

        ndr_desc->nd_mapping = nd_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;
        }

 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->nvdimm_bus,
                                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_done || !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.
         */

        /* 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_done = 1;
                else
                        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);
        mutex_unlock(&acpi_desc->init_mutex);
}

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

        list_for_each_entry(nfit_spa, &acpi_desc->spas, list)
                if (nfit_spa_type(nfit_spa->spa) == NFIT_SPA_DCR) {
                        /* 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;
}

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);

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;

        /* 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);
        return wait_for_completion_interruptible(&flush.cmp);
}

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;
}

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->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->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);
        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;

        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);

        acpi_desc->cancel = 1;
        flush_workqueue(nfit_wq);
        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;
        } else {
                /*
                 * Finish previous registration before considering new
                 * regions.
                 */
                flush_workqueue(nfit_wq);
        }

        /* 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]);

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

        return acpi_bus_register_driver(&acpi_nfit_driver);
}

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

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