/*
 * NVM Express device driver
 * Copyright (c) 2011-2014, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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/aer.h>
#include <linux/bitops.h>
#include <linux/blkdev.h>
#include <linux/blk-mq.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/genhd.h>
#include <linux/hdreg.h>
#include <linux/idr.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kdev_t.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/poison.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/t10-pi.h>
#include <linux/timer.h>
#include <linux/types.h>
#include <linux/io-64-nonatomic-lo-hi.h>
#include <asm/unaligned.h>

#include "nvme.h"

#define NVME_Q_DEPTH            1024
#define NVME_AQ_DEPTH           256
#define SQ_SIZE(depth)          (depth * sizeof(struct nvme_command))
#define CQ_SIZE(depth)          (depth * sizeof(struct nvme_completion))
                
/*
 * We handle AEN commands ourselves and don't even let the
 * block layer know about them.
 */
#define NVME_AQ_BLKMQ_DEPTH     (NVME_AQ_DEPTH - NVME_NR_AERS)

static int use_threaded_interrupts;
module_param(use_threaded_interrupts, int, 0);

static bool use_cmb_sqes = true;
module_param(use_cmb_sqes, bool, 0644);
MODULE_PARM_DESC(use_cmb_sqes, "use controller's memory buffer for I/O SQes");

static struct workqueue_struct *nvme_workq;

struct nvme_dev;
struct nvme_queue;

static int nvme_reset(struct nvme_dev *dev);
static void nvme_process_cq(struct nvme_queue *nvmeq);
static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown);

/*
 * Represents an NVM Express device.  Each nvme_dev is a PCI function.
 */
struct nvme_dev {
        struct nvme_queue **queues;
        struct blk_mq_tag_set tagset;
        struct blk_mq_tag_set admin_tagset;
        u32 __iomem *dbs;
        struct device *dev;
        struct dma_pool *prp_page_pool;
        struct dma_pool *prp_small_pool;
        unsigned queue_count;
        unsigned online_queues;
        unsigned max_qid;
        int q_depth;
        u32 db_stride;
        struct msix_entry *entry;
        void __iomem *bar;
        struct work_struct reset_work;
        struct work_struct remove_work;
        struct timer_list watchdog_timer;
        struct mutex shutdown_lock;
        bool subsystem;
        void __iomem *cmb;
        dma_addr_t cmb_dma_addr;
        u64 cmb_size;
        u32 cmbsz;
        struct nvme_ctrl ctrl;
        struct completion ioq_wait;
};

static inline struct nvme_dev *to_nvme_dev(struct nvme_ctrl *ctrl)
{
        return container_of(ctrl, struct nvme_dev, ctrl);
}

/*
 * An NVM Express queue.  Each device has at least two (one for admin
 * commands and one for I/O commands).
 */
struct nvme_queue {
        struct device *q_dmadev;
        struct nvme_dev *dev;
        char irqname[24];       /* nvme4294967295-65535\0 */
        spinlock_t q_lock;
        struct nvme_command *sq_cmds;
        struct nvme_command __iomem *sq_cmds_io;
        volatile struct nvme_completion *cqes;
        struct blk_mq_tags **tags;
        dma_addr_t sq_dma_addr;
        dma_addr_t cq_dma_addr;
        u32 __iomem *q_db;
        u16 q_depth;
        s16 cq_vector;
        u16 sq_tail;
        u16 cq_head;
        u16 qid;
        u8 cq_phase;
        u8 cqe_seen;
};

/*
 * The nvme_iod describes the data in an I/O, including the list of PRP
 * entries.  You can't see it in this data structure because C doesn't let
 * me express that.  Use nvme_init_iod to ensure there's enough space
 * allocated to store the PRP list.
 */
struct nvme_iod {
        struct nvme_queue *nvmeq;
        int aborted;
        int npages;             /* In the PRP list. 0 means small pool in use */
        int nents;              /* Used in scatterlist */
        int length;             /* Of data, in bytes */
        dma_addr_t first_dma;
        struct scatterlist meta_sg; /* metadata requires single contiguous buffer */
        struct scatterlist *sg;
        struct scatterlist inline_sg[0];
};

/*
 * Check we didin't inadvertently grow the command struct
 */
static inline void _nvme_check_size(void)
{
        BUILD_BUG_ON(sizeof(struct nvme_rw_command) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_create_cq) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_create_sq) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_delete_queue) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_features) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_format_cmd) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_abort_cmd) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_command) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_id_ctrl) != 4096);
        BUILD_BUG_ON(sizeof(struct nvme_id_ns) != 4096);
        BUILD_BUG_ON(sizeof(struct nvme_lba_range_type) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_smart_log) != 512);
}

/*
 * Max size of iod being embedded in the request payload
 */
#define NVME_INT_PAGES          2
#define NVME_INT_BYTES(dev)     (NVME_INT_PAGES * (dev)->ctrl.page_size)

/*
 * Will slightly overestimate the number of pages needed.  This is OK
 * as it only leads to a small amount of wasted memory for the lifetime of
 * the I/O.
 */
static int nvme_npages(unsigned size, struct nvme_dev *dev)
{
        unsigned nprps = DIV_ROUND_UP(size + dev->ctrl.page_size,
                                      dev->ctrl.page_size);
        return DIV_ROUND_UP(8 * nprps, PAGE_SIZE - 8);
}

static unsigned int nvme_iod_alloc_size(struct nvme_dev *dev,
                unsigned int size, unsigned int nseg)
{
        return sizeof(__le64 *) * nvme_npages(size, dev) +
                        sizeof(struct scatterlist) * nseg;
}

static unsigned int nvme_cmd_size(struct nvme_dev *dev)
{
        return sizeof(struct nvme_iod) +
                nvme_iod_alloc_size(dev, NVME_INT_BYTES(dev), NVME_INT_PAGES);
}

static int nvme_admin_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
                                unsigned int hctx_idx)
{
        struct nvme_dev *dev = data;
        struct nvme_queue *nvmeq = dev->queues[0];

        WARN_ON(hctx_idx != 0);
        WARN_ON(dev->admin_tagset.tags[0] != hctx->tags);
        WARN_ON(nvmeq->tags);

        hctx->driver_data = nvmeq;
        nvmeq->tags = &dev->admin_tagset.tags[0];
        return 0;
}

static void nvme_admin_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
{
        struct nvme_queue *nvmeq = hctx->driver_data;

        nvmeq->tags = NULL;
}

static int nvme_admin_init_request(void *data, struct request *req,
                                unsigned int hctx_idx, unsigned int rq_idx,
                                unsigned int numa_node)
{
        struct nvme_dev *dev = data;
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct nvme_queue *nvmeq = dev->queues[0];

        BUG_ON(!nvmeq);
        iod->nvmeq = nvmeq;
        return 0;
}

static int nvme_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
                          unsigned int hctx_idx)
{
        struct nvme_dev *dev = data;
        struct nvme_queue *nvmeq = dev->queues[hctx_idx + 1];

        if (!nvmeq->tags)
                nvmeq->tags = &dev->tagset.tags[hctx_idx];

        WARN_ON(dev->tagset.tags[hctx_idx] != hctx->tags);
        hctx->driver_data = nvmeq;
        return 0;
}

static int nvme_init_request(void *data, struct request *req,
                                unsigned int hctx_idx, unsigned int rq_idx,
                                unsigned int numa_node)
{
        struct nvme_dev *dev = data;
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct nvme_queue *nvmeq = dev->queues[hctx_idx + 1];

        BUG_ON(!nvmeq);
        iod->nvmeq = nvmeq;
        return 0;
}

/**
 * __nvme_submit_cmd() - Copy a command into a queue and ring the doorbell
 * @nvmeq: The queue to use
 * @cmd: The command to send
 *
 * Safe to use from interrupt context
 */
static void __nvme_submit_cmd(struct nvme_queue *nvmeq,
                                                struct nvme_command *cmd)
{
        u16 tail = nvmeq->sq_tail;

        if (nvmeq->sq_cmds_io)
                memcpy_toio(&nvmeq->sq_cmds_io[tail], cmd, sizeof(*cmd));
        else
                memcpy(&nvmeq->sq_cmds[tail], cmd, sizeof(*cmd));

        if (++tail == nvmeq->q_depth)
                tail = 0;
        writel(tail, nvmeq->q_db);
        nvmeq->sq_tail = tail;
}

static __le64 **iod_list(struct request *req)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        return (__le64 **)(iod->sg + req->nr_phys_segments);
}

static int nvme_init_iod(struct request *rq, unsigned size,
                struct nvme_dev *dev)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(rq);
        int nseg = rq->nr_phys_segments;

        if (nseg > NVME_INT_PAGES || size > NVME_INT_BYTES(dev)) {
                iod->sg = kmalloc(nvme_iod_alloc_size(dev, size, nseg), GFP_ATOMIC);
                if (!iod->sg)
                        return BLK_MQ_RQ_QUEUE_BUSY;
        } else {
                iod->sg = iod->inline_sg;
        }

        iod->aborted = 0;
        iod->npages = -1;
        iod->nents = 0;
        iod->length = size;
        return 0;
}

static void nvme_free_iod(struct nvme_dev *dev, struct request *req)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        const int last_prp = dev->ctrl.page_size / 8 - 1;
        int i;
        __le64 **list = iod_list(req);
        dma_addr_t prp_dma = iod->first_dma;

        nvme_cleanup_cmd(req);

        if (iod->npages == 0)
                dma_pool_free(dev->prp_small_pool, list[0], prp_dma);
        for (i = 0; i < iod->npages; i++) {
                __le64 *prp_list = list[i];
                dma_addr_t next_prp_dma = le64_to_cpu(prp_list[last_prp]);
                dma_pool_free(dev->prp_page_pool, prp_list, prp_dma);
                prp_dma = next_prp_dma;
        }

        if (iod->sg != iod->inline_sg)
                kfree(iod->sg);
}

#ifdef CONFIG_BLK_DEV_INTEGRITY
static void nvme_dif_prep(u32 p, u32 v, struct t10_pi_tuple *pi)
{
        if (be32_to_cpu(pi->ref_tag) == v)
                pi->ref_tag = cpu_to_be32(p);
}

static void nvme_dif_complete(u32 p, u32 v, struct t10_pi_tuple *pi)
{
        if (be32_to_cpu(pi->ref_tag) == p)
                pi->ref_tag = cpu_to_be32(v);
}

/**
 * nvme_dif_remap - remaps ref tags to bip seed and physical lba
 *
 * The virtual start sector is the one that was originally submitted by the
 * block layer. Due to partitioning, MD/DM cloning, etc. the actual physical
 * start sector may be different. Remap protection information to match the
 * physical LBA on writes, and back to the original seed on reads.
 *
 * Type 0 and 3 do not have a ref tag, so no remapping required.
 */
static void nvme_dif_remap(struct request *req,
                        void (*dif_swap)(u32 p, u32 v, struct t10_pi_tuple *pi))
{
        struct nvme_ns *ns = req->rq_disk->private_data;
        struct bio_integrity_payload *bip;
        struct t10_pi_tuple *pi;
        void *p, *pmap;
        u32 i, nlb, ts, phys, virt;

        if (!ns->pi_type || ns->pi_type == NVME_NS_DPS_PI_TYPE3)
                return;

        bip = bio_integrity(req->bio);
        if (!bip)
                return;

        pmap = kmap_atomic(bip->bip_vec->bv_page) + bip->bip_vec->bv_offset;

        p = pmap;
        virt = bip_get_seed(bip);
        phys = nvme_block_nr(ns, blk_rq_pos(req));
        nlb = (blk_rq_bytes(req) >> ns->lba_shift);
        ts = ns->disk->queue->integrity.tuple_size;

        for (i = 0; i < nlb; i++, virt++, phys++) {
                pi = (struct t10_pi_tuple *)p;
                dif_swap(phys, virt, pi);
                p += ts;
        }
        kunmap_atomic(pmap);
}
#else /* CONFIG_BLK_DEV_INTEGRITY */
static void nvme_dif_remap(struct request *req,
                        void (*dif_swap)(u32 p, u32 v, struct t10_pi_tuple *pi))
{
}
static void nvme_dif_prep(u32 p, u32 v, struct t10_pi_tuple *pi)
{
}
static void nvme_dif_complete(u32 p, u32 v, struct t10_pi_tuple *pi)
{
}
#endif

static bool nvme_setup_prps(struct nvme_dev *dev, struct request *req,
                int total_len)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct dma_pool *pool;
        int length = total_len;
        struct scatterlist *sg = iod->sg;
        int dma_len = sg_dma_len(sg);
        u64 dma_addr = sg_dma_address(sg);
        u32 page_size = dev->ctrl.page_size;
        int offset = dma_addr & (page_size - 1);
        __le64 *prp_list;
        __le64 **list = iod_list(req);
        dma_addr_t prp_dma;
        int nprps, i;

        length -= (page_size - offset);
        if (length <= 0)
                return true;

        dma_len -= (page_size - offset);
        if (dma_len) {
                dma_addr += (page_size - offset);
        } else {
                sg = sg_next(sg);
                dma_addr = sg_dma_address(sg);
                dma_len = sg_dma_len(sg);
        }

        if (length <= page_size) {
                iod->first_dma = dma_addr;
                return true;
        }

        nprps = DIV_ROUND_UP(length, page_size);
        if (nprps <= (256 / 8)) {
                pool = dev->prp_small_pool;
                iod->npages = 0;
        } else {
                pool = dev->prp_page_pool;
                iod->npages = 1;
        }

        prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma);
        if (!prp_list) {
                iod->first_dma = dma_addr;
                iod->npages = -1;
                return false;
        }
        list[0] = prp_list;
        iod->first_dma = prp_dma;
        i = 0;
        for (;;) {
                if (i == page_size >> 3) {
                        __le64 *old_prp_list = prp_list;
                        prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma);
                        if (!prp_list)
                                return false;
                        list[iod->npages++] = prp_list;
                        prp_list[0] = old_prp_list[i - 1];
                        old_prp_list[i - 1] = cpu_to_le64(prp_dma);
                        i = 1;
                }
                prp_list[i++] = cpu_to_le64(dma_addr);
                dma_len -= page_size;
                dma_addr += page_size;
                length -= page_size;
                if (length <= 0)
                        break;
                if (dma_len > 0)
                        continue;
                BUG_ON(dma_len < 0);
                sg = sg_next(sg);
                dma_addr = sg_dma_address(sg);
                dma_len = sg_dma_len(sg);
        }

        return true;
}

static int nvme_map_data(struct nvme_dev *dev, struct request *req,
                unsigned size, struct nvme_command *cmnd)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct request_queue *q = req->q;
        enum dma_data_direction dma_dir = rq_data_dir(req) ?
                        DMA_TO_DEVICE : DMA_FROM_DEVICE;
        int ret = BLK_MQ_RQ_QUEUE_ERROR;

        sg_init_table(iod->sg, req->nr_phys_segments);
        iod->nents = blk_rq_map_sg(q, req, iod->sg);
        if (!iod->nents)
                goto out;

        ret = BLK_MQ_RQ_QUEUE_BUSY;
        if (!dma_map_sg(dev->dev, iod->sg, iod->nents, dma_dir))
                goto out;

        if (!nvme_setup_prps(dev, req, size))
                goto out_unmap;

        ret = BLK_MQ_RQ_QUEUE_ERROR;
        if (blk_integrity_rq(req)) {
                if (blk_rq_count_integrity_sg(q, req->bio) != 1)
                        goto out_unmap;

                sg_init_table(&iod->meta_sg, 1);
                if (blk_rq_map_integrity_sg(q, req->bio, &iod->meta_sg) != 1)
                        goto out_unmap;

                if (rq_data_dir(req))
                        nvme_dif_remap(req, nvme_dif_prep);

                if (!dma_map_sg(dev->dev, &iod->meta_sg, 1, dma_dir))
                        goto out_unmap;
        }

        cmnd->rw.prp1 = cpu_to_le64(sg_dma_address(iod->sg));
        cmnd->rw.prp2 = cpu_to_le64(iod->first_dma);
        if (blk_integrity_rq(req))
                cmnd->rw.metadata = cpu_to_le64(sg_dma_address(&iod->meta_sg));
        return BLK_MQ_RQ_QUEUE_OK;

out_unmap:
        dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir);
out:
        return ret;
}

static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        enum dma_data_direction dma_dir = rq_data_dir(req) ?
                        DMA_TO_DEVICE : DMA_FROM_DEVICE;

        if (iod->nents) {
                dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir);
                if (blk_integrity_rq(req)) {
                        if (!rq_data_dir(req))
                                nvme_dif_remap(req, nvme_dif_complete);
                        dma_unmap_sg(dev->dev, &iod->meta_sg, 1, dma_dir);
                }
        }

        nvme_free_iod(dev, req);
}

/*
 * NOTE: ns is NULL when called on the admin queue.
 */
static int nvme_queue_rq(struct blk_mq_hw_ctx *hctx,
                         const struct blk_mq_queue_data *bd)
{
        struct nvme_ns *ns = hctx->queue->queuedata;
        struct nvme_queue *nvmeq = hctx->driver_data;
        struct nvme_dev *dev = nvmeq->dev;
        struct request *req = bd->rq;
        struct nvme_command cmnd;
        unsigned map_len;
        int ret = BLK_MQ_RQ_QUEUE_OK;

        /*
         * If formated with metadata, require the block layer provide a buffer
         * unless this namespace is formated such that the metadata can be
         * stripped/generated by the controller with PRACT=1.
         */
        if (ns && ns->ms && !blk_integrity_rq(req)) {
                if (!(ns->pi_type && ns->ms == 8) &&
                                        req->cmd_type != REQ_TYPE_DRV_PRIV) {
                        blk_mq_end_request(req, -EFAULT);
                        return BLK_MQ_RQ_QUEUE_OK;
                }
        }

        map_len = nvme_map_len(req);
        ret = nvme_init_iod(req, map_len, dev);
        if (ret)
                return ret;

        ret = nvme_setup_cmd(ns, req, &cmnd);
        if (ret)
                goto out;

        if (req->nr_phys_segments)
                ret = nvme_map_data(dev, req, map_len, &cmnd);

        if (ret)
                goto out;

        cmnd.common.command_id = req->tag;
        blk_mq_start_request(req);

        spin_lock_irq(&nvmeq->q_lock);
        if (unlikely(nvmeq->cq_vector < 0)) {
                if (ns && !test_bit(NVME_NS_DEAD, &ns->flags))
                        ret = BLK_MQ_RQ_QUEUE_BUSY;
                else
                        ret = BLK_MQ_RQ_QUEUE_ERROR;
                spin_unlock_irq(&nvmeq->q_lock);
                goto out;
        }
        __nvme_submit_cmd(nvmeq, &cmnd);
        nvme_process_cq(nvmeq);
        spin_unlock_irq(&nvmeq->q_lock);
        return BLK_MQ_RQ_QUEUE_OK;
out:
        nvme_free_iod(dev, req);
        return ret;
}

static void nvme_complete_rq(struct request *req)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct nvme_dev *dev = iod->nvmeq->dev;
        int error = 0;

        nvme_unmap_data(dev, req);

        if (unlikely(req->errors)) {
                if (nvme_req_needs_retry(req, req->errors)) {
                        nvme_requeue_req(req);
                        return;
                }

                if (req->cmd_type == REQ_TYPE_DRV_PRIV)
                        error = req->errors;
                else
                        error = nvme_error_status(req->errors);
        }

        if (unlikely(iod->aborted)) {
                dev_warn(dev->ctrl.device,
                        "completing aborted command with status: %04x\n",
                        req->errors);
        }

        blk_mq_end_request(req, error);
}

/* We read the CQE phase first to check if the rest of the entry is valid */
static inline bool nvme_cqe_valid(struct nvme_queue *nvmeq, u16 head,
                u16 phase)
{
        return (le16_to_cpu(nvmeq->cqes[head].status) & 1) == phase;
}

static void __nvme_process_cq(struct nvme_queue *nvmeq, unsigned int *tag)
{
        u16 head, phase;

        head = nvmeq->cq_head;
        phase = nvmeq->cq_phase;

        while (nvme_cqe_valid(nvmeq, head, phase)) {
                struct nvme_completion cqe = nvmeq->cqes[head];
                struct request *req;

                if (++head == nvmeq->q_depth) {
                        head = 0;
                        phase = !phase;
                }

                if (tag && *tag == cqe.command_id)
                        *tag = -1;

                if (unlikely(cqe.command_id >= nvmeq->q_depth)) {
                        dev_warn(nvmeq->dev->ctrl.device,
                                "invalid id %d completed on queue %d\n",
                                cqe.command_id, le16_to_cpu(cqe.sq_id));
                        continue;
                }

                /*
                 * AEN requests are special as they don't time out and can
                 * survive any kind of queue freeze and often don't respond to
                 * aborts.  We don't even bother to allocate a struct request
                 * for them but rather special case them here.
                 */
                if (unlikely(nvmeq->qid == 0 &&
                                cqe.command_id >= NVME_AQ_BLKMQ_DEPTH)) {
                        nvme_complete_async_event(&nvmeq->dev->ctrl, &cqe);
                        continue;
                }

                req = blk_mq_tag_to_rq(*nvmeq->tags, cqe.command_id);
                if (req->cmd_type == REQ_TYPE_DRV_PRIV && req->special)
                        memcpy(req->special, &cqe, sizeof(cqe));
                blk_mq_complete_request(req, le16_to_cpu(cqe.status) >> 1);

        }

        /* If the controller ignores the cq head doorbell and continuously
         * writes to the queue, it is theoretically possible to wrap around
         * the queue twice and mistakenly return IRQ_NONE.  Linux only
         * requires that 0.1% of your interrupts are handled, so this isn't
         * a big problem.
         */
        if (head == nvmeq->cq_head && phase == nvmeq->cq_phase)
                return;

        if (likely(nvmeq->cq_vector >= 0))
                writel(head, nvmeq->q_db + nvmeq->dev->db_stride);
        nvmeq->cq_head = head;
        nvmeq->cq_phase = phase;

        nvmeq->cqe_seen = 1;
}

static void nvme_process_cq(struct nvme_queue *nvmeq)
{
        __nvme_process_cq(nvmeq, NULL);
}

static irqreturn_t nvme_irq(int irq, void *data)
{
        irqreturn_t result;
        struct nvme_queue *nvmeq = data;
        spin_lock(&nvmeq->q_lock);
        nvme_process_cq(nvmeq);
        result = nvmeq->cqe_seen ? IRQ_HANDLED : IRQ_NONE;
        nvmeq->cqe_seen = 0;
        spin_unlock(&nvmeq->q_lock);
        return result;
}

static irqreturn_t nvme_irq_check(int irq, void *data)
{
        struct nvme_queue *nvmeq = data;
        if (nvme_cqe_valid(nvmeq, nvmeq->cq_head, nvmeq->cq_phase))
                return IRQ_WAKE_THREAD;
        return IRQ_NONE;
}

static int nvme_poll(struct blk_mq_hw_ctx *hctx, unsigned int tag)
{
        struct nvme_queue *nvmeq = hctx->driver_data;

        if (nvme_cqe_valid(nvmeq, nvmeq->cq_head, nvmeq->cq_phase)) {
                spin_lock_irq(&nvmeq->q_lock);
                __nvme_process_cq(nvmeq, &tag);
                spin_unlock_irq(&nvmeq->q_lock);

                if (tag == -1)
                        return 1;
        }

        return 0;
}

static void nvme_pci_submit_async_event(struct nvme_ctrl *ctrl, int aer_idx)
{
        struct nvme_dev *dev = to_nvme_dev(ctrl);
        struct nvme_queue *nvmeq = dev->queues[0];
        struct nvme_command c;

        memset(&c, 0, sizeof(c));
        c.common.opcode = nvme_admin_async_event;
        c.common.command_id = NVME_AQ_BLKMQ_DEPTH + aer_idx;

        spin_lock_irq(&nvmeq->q_lock);
        __nvme_submit_cmd(nvmeq, &c);
        spin_unlock_irq(&nvmeq->q_lock);
}

static int adapter_delete_queue(struct nvme_dev *dev, u8 opcode, u16 id)
{
        struct nvme_command c;

        memset(&c, 0, sizeof(c));
        c.delete_queue.opcode = opcode;
        c.delete_queue.qid = cpu_to_le16(id);

        return nvme_submit_sync_cmd(dev->ctrl.admin_q, &c, NULL, 0);
}

static int adapter_alloc_cq(struct nvme_dev *dev, u16 qid,
                                                struct nvme_queue *nvmeq)
{
        struct nvme_command c;
        int flags = NVME_QUEUE_PHYS_CONTIG | NVME_CQ_IRQ_ENABLED;

        /*
         * Note: we (ab)use the fact the the prp fields survive if no data
         * is attached to the request.
         */
        memset(&c, 0, sizeof(c));
        c.create_cq.opcode = nvme_admin_create_cq;
        c.create_cq.prp1 = cpu_to_le64(nvmeq->cq_dma_addr);
        c.create_cq.cqid = cpu_to_le16(qid);
        c.create_cq.qsize = cpu_to_le16(nvmeq->q_depth - 1);
        c.create_cq.cq_flags = cpu_to_le16(flags);
        c.create_cq.irq_vector = cpu_to_le16(nvmeq->cq_vector);

        return nvme_submit_sync_cmd(dev->ctrl.admin_q, &c, NULL, 0);
}

static int adapter_alloc_sq(struct nvme_dev *dev, u16 qid,
                                                struct nvme_queue *nvmeq)
{
        struct nvme_command c;
        int flags = NVME_QUEUE_PHYS_CONTIG | NVME_SQ_PRIO_MEDIUM;

        /*
         * Note: we (ab)use the fact the the prp fields survive if no data
         * is attached to the request.
         */
        memset(&c, 0, sizeof(c));
        c.create_sq.opcode = nvme_admin_create_sq;
        c.create_sq.prp1 = cpu_to_le64(nvmeq->sq_dma_addr);
        c.create_sq.sqid = cpu_to_le16(qid);
        c.create_sq.qsize = cpu_to_le16(nvmeq->q_depth - 1);
        c.create_sq.sq_flags = cpu_to_le16(flags);
        c.create_sq.cqid = cpu_to_le16(qid);

        return nvme_submit_sync_cmd(dev->ctrl.admin_q, &c, NULL, 0);
}

static int adapter_delete_cq(struct nvme_dev *dev, u16 cqid)
{
        return adapter_delete_queue(dev, nvme_admin_delete_cq, cqid);
}

static int adapter_delete_sq(struct nvme_dev *dev, u16 sqid)
{
        return adapter_delete_queue(dev, nvme_admin_delete_sq, sqid);
}

static void abort_endio(struct request *req, int error)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct nvme_queue *nvmeq = iod->nvmeq;
        u16 status = req->errors;

        dev_warn(nvmeq->dev->ctrl.device, "Abort status: 0x%x", status);
        atomic_inc(&nvmeq->dev->ctrl.abort_limit);
        blk_mq_free_request(req);
}

static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct nvme_queue *nvmeq = iod->nvmeq;
        struct nvme_dev *dev = nvmeq->dev;
        struct request *abort_req;
        struct nvme_command cmd;

        /*
         * Shutdown immediately if controller times out while starting. The
         * reset work will see the pci device disabled when it gets the forced
         * cancellation error. All outstanding requests are completed on
         * shutdown, so we return BLK_EH_HANDLED.
         */
        if (dev->ctrl.state == NVME_CTRL_RESETTING) {
                dev_warn(dev->ctrl.device,
                         "I/O %d QID %d timeout, disable controller\n",
                         req->tag, nvmeq->qid);
                nvme_dev_disable(dev, false);
                req->errors = NVME_SC_CANCELLED;
                return BLK_EH_HANDLED;
        }

        /*
         * Shutdown the controller immediately and schedule a reset if the
         * command was already aborted once before and still hasn't been
         * returned to the driver, or if this is the admin queue.
         */
        if (!nvmeq->qid || iod->aborted) {
                dev_warn(dev->ctrl.device,
                         "I/O %d QID %d timeout, reset controller\n",
                         req->tag, nvmeq->qid);
                nvme_dev_disable(dev, false);
                queue_work(nvme_workq, &dev->reset_work);

                /*
                 * Mark the request as handled, since the inline shutdown
                 * forces all outstanding requests to complete.
                 */
                req->errors = NVME_SC_CANCELLED;
                return BLK_EH_HANDLED;
        }

        iod->aborted = 1;

        if (atomic_dec_return(&dev->ctrl.abort_limit) < 0) {
                atomic_inc(&dev->ctrl.abort_limit);
                return BLK_EH_RESET_TIMER;
        }

        memset(&cmd, 0, sizeof(cmd));
        cmd.abort.opcode = nvme_admin_abort_cmd;
        cmd.abort.cid = req->tag;
        cmd.abort.sqid = cpu_to_le16(nvmeq->qid);

        dev_warn(nvmeq->dev->ctrl.device,
                "I/O %d QID %d timeout, aborting\n",
                 req->tag, nvmeq->qid);

        abort_req = nvme_alloc_request(dev->ctrl.admin_q, &cmd,
                        BLK_MQ_REQ_NOWAIT);
        if (IS_ERR(abort_req)) {
                atomic_inc(&dev->ctrl.abort_limit);
                return BLK_EH_RESET_TIMER;
        }

        abort_req->timeout = ADMIN_TIMEOUT;
        abort_req->end_io_data = NULL;
        blk_execute_rq_nowait(abort_req->q, NULL, abort_req, 0, abort_endio);

        /*
         * The aborted req will be completed on receiving the abort req.
         * We enable the timer again. If hit twice, it'll cause a device reset,
         * as the device then is in a faulty state.
         */
        return BLK_EH_RESET_TIMER;
}

static void nvme_cancel_io(struct request *req, void *data, bool reserved)
{
        int status;

        if (!blk_mq_request_started(req))
                return;

        dev_dbg_ratelimited(((struct nvme_dev *) data)->ctrl.device,
                                "Cancelling I/O %d", req->tag);

        status = NVME_SC_ABORT_REQ;
        if (blk_queue_dying(req->q))
                status |= NVME_SC_DNR;
        blk_mq_complete_request(req, status);
}

static void nvme_free_queue(struct nvme_queue *nvmeq)
{
        dma_free_coherent(nvmeq->q_dmadev, CQ_SIZE(nvmeq->q_depth),
                                (void *)nvmeq->cqes, nvmeq->cq_dma_addr);
        if (nvmeq->sq_cmds)
                dma_free_coherent(nvmeq->q_dmadev, SQ_SIZE(nvmeq->q_depth),
                                        nvmeq->sq_cmds, nvmeq->sq_dma_addr);
        kfree(nvmeq);
}

static void nvme_free_queues(struct nvme_dev *dev, int lowest)
{
        int i;

        for (i = dev->queue_count - 1; i >= lowest; i--) {
                struct nvme_queue *nvmeq = dev->queues[i];
                dev->queue_count--;
                dev->queues[i] = NULL;
                nvme_free_queue(nvmeq);
        }
}

/**
 * nvme_suspend_queue - put queue into suspended state
 * @nvmeq - queue to suspend
 */
static int nvme_suspend_queue(struct nvme_queue *nvmeq)
{
        int vector;

        spin_lock_irq(&nvmeq->q_lock);
        if (nvmeq->cq_vector == -1) {
                spin_unlock_irq(&nvmeq->q_lock);
                return 1;
        }
        vector = nvmeq->dev->entry[nvmeq->cq_vector].vector;
        nvmeq->dev->online_queues--;
        nvmeq->cq_vector = -1;
        spin_unlock_irq(&nvmeq->q_lock);

        if (!nvmeq->qid && nvmeq->dev->ctrl.admin_q)
                blk_mq_stop_hw_queues(nvmeq->dev->ctrl.admin_q);

        irq_set_affinity_hint(vector, NULL);
        free_irq(vector, nvmeq);

        return 0;
}

static void nvme_disable_admin_queue(struct nvme_dev *dev, bool shutdown)
{
        struct nvme_queue *nvmeq = dev->queues[0];

        if (!nvmeq)
                return;
        if (nvme_suspend_queue(nvmeq))
                return;

        if (shutdown)
                nvme_shutdown_ctrl(&dev->ctrl);
        else
                nvme_disable_ctrl(&dev->ctrl, lo_hi_readq(
                                                dev->bar + NVME_REG_CAP));

        spin_lock_irq(&nvmeq->q_lock);
        nvme_process_cq(nvmeq);
        spin_unlock_irq(&nvmeq->q_lock);
}

static int nvme_cmb_qdepth(struct nvme_dev *dev, int nr_io_queues,
                                int entry_size)
{
        int q_depth = dev->q_depth;
        unsigned q_size_aligned = roundup(q_depth * entry_size,
                                          dev->ctrl.page_size);

        if (q_size_aligned * nr_io_queues > dev->cmb_size) {
                u64 mem_per_q = div_u64(dev->cmb_size, nr_io_queues);
                mem_per_q = round_down(mem_per_q, dev->ctrl.page_size);
                q_depth = div_u64(mem_per_q, entry_size);

                /*
                 * Ensure the reduced q_depth is above some threshold where it
                 * would be better to map queues in system memory with the
                 * original depth
                 */
                if (q_depth < 64)
                        return -ENOMEM;
        }

        return q_depth;
}

static int nvme_alloc_sq_cmds(struct nvme_dev *dev, struct nvme_queue *nvmeq,
                                int qid, int depth)
{
        if (qid && dev->cmb && use_cmb_sqes && NVME_CMB_SQS(dev->cmbsz)) {
                unsigned offset = (qid - 1) * roundup(SQ_SIZE(depth),
                                                      dev->ctrl.page_size);
                nvmeq->sq_dma_addr = dev->cmb_dma_addr + offset;
                nvmeq->sq_cmds_io = dev->cmb + offset;
        } else {
                nvmeq->sq_cmds = dma_alloc_coherent(dev->dev, SQ_SIZE(depth),
                                        &nvmeq->sq_dma_addr, GFP_KERNEL);
                if (!nvmeq->sq_cmds)
                        return -ENOMEM;
        }

        return 0;
}

static struct nvme_queue *nvme_alloc_queue(struct nvme_dev *dev, int qid,
                                                        int depth)
{
        struct nvme_queue *nvmeq = kzalloc(sizeof(*nvmeq), GFP_KERNEL);
        if (!nvmeq)
                return NULL;

        nvmeq->cqes = dma_zalloc_coherent(dev->dev, CQ_SIZE(depth),
                                          &nvmeq->cq_dma_addr, GFP_KERNEL);
        if (!nvmeq->cqes)
                goto free_nvmeq;

        if (nvme_alloc_sq_cmds(dev, nvmeq, qid, depth))
                goto free_cqdma;

        nvmeq->q_dmadev = dev->dev;
        nvmeq->dev = dev;
        snprintf(nvmeq->irqname, sizeof(nvmeq->irqname), "nvme%dq%d",
                        dev->ctrl.instance, qid);
        spin_lock_init(&nvmeq->q_lock);
        nvmeq->cq_head = 0;
        nvmeq->cq_phase = 1;
        nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
        nvmeq->q_depth = depth;
        nvmeq->qid = qid;
        nvmeq->cq_vector = -1;
        dev->queues[qid] = nvmeq;
        dev->queue_count++;

        return nvmeq;

 free_cqdma:
        dma_free_coherent(dev->dev, CQ_SIZE(depth), (void *)nvmeq->cqes,
                                                        nvmeq->cq_dma_addr);
 free_nvmeq:
        kfree(nvmeq);
        return NULL;
}

static int queue_request_irq(struct nvme_dev *dev, struct nvme_queue *nvmeq,
                                                        const char *name)
{
        if (use_threaded_interrupts)
                return request_threaded_irq(dev->entry[nvmeq->cq_vector].vector,
                                        nvme_irq_check, nvme_irq, IRQF_SHARED,
                                        name, nvmeq);
        return request_irq(dev->entry[nvmeq->cq_vector].vector, nvme_irq,
                                IRQF_SHARED, name, nvmeq);
}

static void nvme_init_queue(struct nvme_queue *nvmeq, u16 qid)
{
        struct nvme_dev *dev = nvmeq->dev;

        spin_lock_irq(&nvmeq->q_lock);
        nvmeq->sq_tail = 0;
        nvmeq->cq_head = 0;
        nvmeq->cq_phase = 1;
        nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
        memset((void *)nvmeq->cqes, 0, CQ_SIZE(nvmeq->q_depth));
        dev->online_queues++;
        spin_unlock_irq(&nvmeq->q_lock);
}

static int nvme_create_queue(struct nvme_queue *nvmeq, int qid)
{
        struct nvme_dev *dev = nvmeq->dev;
        int result;

        nvmeq->cq_vector = qid - 1;
        result = adapter_alloc_cq(dev, qid, nvmeq);
        if (result < 0)
                return result;

        result = adapter_alloc_sq(dev, qid, nvmeq);
        if (result < 0)
                goto release_cq;

        result = queue_request_irq(dev, nvmeq, nvmeq->irqname);
        if (result < 0)
                goto release_sq;

        nvme_init_queue(nvmeq, qid);
        return result;

 release_sq:
        adapter_delete_sq(dev, qid);
 release_cq:
        adapter_delete_cq(dev, qid);
        return result;
}

static struct blk_mq_ops nvme_mq_admin_ops = {
        .queue_rq       = nvme_queue_rq,
        .complete       = nvme_complete_rq,
        .map_queue      = blk_mq_map_queue,
        .init_hctx      = nvme_admin_init_hctx,
        .exit_hctx      = nvme_admin_exit_hctx,
        .init_request   = nvme_admin_init_request,
        .timeout        = nvme_timeout,
};

static struct blk_mq_ops nvme_mq_ops = {
        .queue_rq       = nvme_queue_rq,
        .complete       = nvme_complete_rq,
        .map_queue      = blk_mq_map_queue,
        .init_hctx      = nvme_init_hctx,
        .init_request   = nvme_init_request,
        .timeout        = nvme_timeout,
        .poll           = nvme_poll,
};

static void nvme_dev_remove_admin(struct nvme_dev *dev)
{
        if (dev->ctrl.admin_q && !blk_queue_dying(dev->ctrl.admin_q)) {
                /*
                 * If the controller was reset during removal, it's possible
                 * user requests may be waiting on a stopped queue. Start the
                 * queue to flush these to completion.
                 */
                blk_mq_start_stopped_hw_queues(dev->ctrl.admin_q, true);
                blk_cleanup_queue(dev->ctrl.admin_q);
                blk_mq_free_tag_set(&dev->admin_tagset);
        }
}

static int nvme_alloc_admin_tags(struct nvme_dev *dev)
{
        if (!dev->ctrl.admin_q) {
                dev->admin_tagset.ops = &nvme_mq_admin_ops;
                dev->admin_tagset.nr_hw_queues = 1;

                /*
                 * Subtract one to leave an empty queue entry for 'Full Queue'
                 * condition. See NVM-Express 1.2 specification, section 4.1.2.
                 */
                dev->admin_tagset.queue_depth = NVME_AQ_BLKMQ_DEPTH - 1;
                dev->admin_tagset.timeout = ADMIN_TIMEOUT;
                dev->admin_tagset.numa_node = dev_to_node(dev->dev);
                dev->admin_tagset.cmd_size = nvme_cmd_size(dev);
                dev->admin_tagset.driver_data = dev;

                if (blk_mq_alloc_tag_set(&dev->admin_tagset))
                        return -ENOMEM;

                dev->ctrl.admin_q = blk_mq_init_queue(&dev->admin_tagset);
                if (IS_ERR(dev->ctrl.admin_q)) {
                        blk_mq_free_tag_set(&dev->admin_tagset);
                        return -ENOMEM;
                }
                if (!blk_get_queue(dev->ctrl.admin_q)) {
                        nvme_dev_remove_admin(dev);
                        dev->ctrl.admin_q = NULL;
                        return -ENODEV;
                }
        } else
                blk_mq_start_stopped_hw_queues(dev->ctrl.admin_q, true);

        return 0;
}

static int nvme_configure_admin_queue(struct nvme_dev *dev)
{
        int result;
        u32 aqa;
        u64 cap = lo_hi_readq(dev->bar + NVME_REG_CAP);
        struct nvme_queue *nvmeq;

        dev->subsystem = readl(dev->bar + NVME_REG_VS) >= NVME_VS(1, 1) ?
                                                NVME_CAP_NSSRC(cap) : 0;

        if (dev->subsystem &&
            (readl(dev->bar + NVME_REG_CSTS) & NVME_CSTS_NSSRO))
                writel(NVME_CSTS_NSSRO, dev->bar + NVME_REG_CSTS);

        result = nvme_disable_ctrl(&dev->ctrl, cap);
        if (result < 0)
                return result;

        nvmeq = dev->queues[0];
        if (!nvmeq) {
                nvmeq = nvme_alloc_queue(dev, 0, NVME_AQ_DEPTH);
                if (!nvmeq)
                        return -ENOMEM;
        }

        aqa = nvmeq->q_depth - 1;
        aqa |= aqa << 16;

        writel(aqa, dev->bar + NVME_REG_AQA);
        lo_hi_writeq(nvmeq->sq_dma_addr, dev->bar + NVME_REG_ASQ);
        lo_hi_writeq(nvmeq->cq_dma_addr, dev->bar + NVME_REG_ACQ);

        result = nvme_enable_ctrl(&dev->ctrl, cap);
        if (result)
                goto free_nvmeq;

        nvmeq->cq_vector = 0;
        result = queue_request_irq(dev, nvmeq, nvmeq->irqname);
        if (result) {
                nvmeq->cq_vector = -1;
                goto free_nvmeq;
        }

        return result;

 free_nvmeq:
        nvme_free_queues(dev, 0);
        return result;
}

static bool nvme_should_reset(struct nvme_dev *dev, u32 csts)
{

        /* If true, indicates loss of adapter communication, possibly by a
         * NVMe Subsystem reset.
         */
        bool nssro = dev->subsystem && (csts & NVME_CSTS_NSSRO);

        /* If there is a reset ongoing, we shouldn't reset again. */
        if (work_busy(&dev->reset_work))
                return false;

        /* We shouldn't reset unless the controller is on fatal error state
         * _or_ if we lost the communication with it.
         */
        if (!(csts & NVME_CSTS_CFS) && !nssro)
                return false;

        /* If PCI error recovery process is happening, we cannot reset or
         * the recovery mechanism will surely fail.
         */
        if (pci_channel_offline(to_pci_dev(dev->dev)))
                return false;

        return true;
}

static void nvme_watchdog_timer(unsigned long data)
{
        struct nvme_dev *dev = (struct nvme_dev *)data;
        u32 csts = readl(dev->bar + NVME_REG_CSTS);

        /* Skip controllers under certain specific conditions. */
        if (nvme_should_reset(dev, csts)) {
                if (queue_work(nvme_workq, &dev->reset_work))
                        dev_warn(dev->dev,
                                "Failed status: 0x%x, reset controller.\n",
                                csts);
                return;
        }

        mod_timer(&dev->watchdog_timer, round_jiffies(jiffies + HZ));
}

static int nvme_create_io_queues(struct nvme_dev *dev)
{
        unsigned i, max;
        int ret = 0;

        for (i = dev->queue_count; i <= dev->max_qid; i++) {
                if (!nvme_alloc_queue(dev, i, dev->q_depth)) {
                        ret = -ENOMEM;
                        break;
                }
        }

        max = min(dev->max_qid, dev->queue_count - 1);
        for (i = dev->online_queues; i <= max; i++) {
                ret = nvme_create_queue(dev->queues[i], i);
                if (ret) {
                        nvme_free_queues(dev, i);
                        break;
                }
        }

        /*
         * Ignore failing Create SQ/CQ commands, we can continue with less
         * than the desired aount of queues, and even a controller without
         * I/O queues an still be used to issue admin commands.  This might
         * be useful to upgrade a buggy firmware for example.
         */
        return ret >= 0 ? 0 : ret;
}

static void __iomem *nvme_map_cmb(struct nvme_dev *dev)
{
        u64 szu, size, offset;
        u32 cmbloc;
        resource_size_t bar_size;
        struct pci_dev *pdev = to_pci_dev(dev->dev);
        void __iomem *cmb;
        dma_addr_t dma_addr;

        if (!use_cmb_sqes)
                return NULL;

        dev->cmbsz = readl(dev->bar + NVME_REG_CMBSZ);
        if (!(NVME_CMB_SZ(dev->cmbsz)))
                return NULL;

        cmbloc = readl(dev->bar + NVME_REG_CMBLOC);

        szu = (u64)1 << (12 + 4 * NVME_CMB_SZU(dev->cmbsz));
        size = szu * NVME_CMB_SZ(dev->cmbsz);
        offset = szu * NVME_CMB_OFST(cmbloc);
        bar_size = pci_resource_len(pdev, NVME_CMB_BIR(cmbloc));

        if (offset > bar_size)
                return NULL;

        /*
         * Controllers may support a CMB size larger than their BAR,
         * for example, due to being behind a bridge. Reduce the CMB to
         * the reported size of the BAR
         */
        if (size > bar_size - offset)
                size = bar_size - offset;

        dma_addr = pci_resource_start(pdev, NVME_CMB_BIR(cmbloc)) + offset;
        cmb = ioremap_wc(dma_addr, size);
        if (!cmb)
                return NULL;

        dev->cmb_dma_addr = dma_addr;
        dev->cmb_size = size;
        return cmb;
}

static inline void nvme_release_cmb(struct nvme_dev *dev)
{
        if (dev->cmb) {
                iounmap(dev->cmb);
                dev->cmb = NULL;
        }
}

static size_t db_bar_size(struct nvme_dev *dev, unsigned nr_io_queues)
{
        return 4096 + ((nr_io_queues + 1) * 8 * dev->db_stride);
}

static int nvme_setup_io_queues(struct nvme_dev *dev)
{
        struct nvme_queue *adminq = dev->queues[0];
        struct pci_dev *pdev = to_pci_dev(dev->dev);
        int result, i, vecs, nr_io_queues, size;

        nr_io_queues = num_online_cpus();
        result = nvme_set_queue_count(&dev->ctrl, &nr_io_queues);
        if (result < 0)
                return result;

        /*
         * Degraded controllers might return an error when setting the queue
         * count.  We still want to be able to bring them online and offer
         * access to the admin queue, as that might be only way to fix them up.
         */
        if (result > 0) {
                dev_err(dev->ctrl.device,
                        "Could not set queue count (%d)\n", result);
                return 0;
        }

        if (dev->cmb && NVME_CMB_SQS(dev->cmbsz)) {
                result = nvme_cmb_qdepth(dev, nr_io_queues,
                                sizeof(struct nvme_command));
                if (result > 0)
                        dev->q_depth = result;
                else
                        nvme_release_cmb(dev);
        }

        size = db_bar_size(dev, nr_io_queues);
        if (size > 8192) {
                iounmap(dev->bar);
                do {
                        dev->bar = ioremap(pci_resource_start(pdev, 0), size);
                        if (dev->bar)
                                break;
                        if (!--nr_io_queues)
                                return -ENOMEM;
                        size = db_bar_size(dev, nr_io_queues);
                } while (1);
                dev->dbs = dev->bar + 4096;
                adminq->q_db = dev->dbs;
        }

        /* Deregister the admin queue's interrupt */
        free_irq(dev->entry[0].vector, adminq);

        /*
         * If we enable msix early due to not intx, disable it again before
         * setting up the full range we need.
         */
        if (pdev->msi_enabled)
                pci_disable_msi(pdev);
        else if (pdev->msix_enabled)
                pci_disable_msix(pdev);

        for (i = 0; i < nr_io_queues; i++)
                dev->entry[i].entry = i;
        vecs = pci_enable_msix_range(pdev, dev->entry, 1, nr_io_queues);
        if (vecs < 0) {
                vecs = pci_enable_msi_range(pdev, 1, min(nr_io_queues, 32));
                if (vecs < 0) {
                        vecs = 1;
                } else {
                        for (i = 0; i < vecs; i++)
                                dev->entry[i].vector = i + pdev->irq;
                }
        }

        /*
         * Should investigate if there's a performance win from allocating
         * more queues than interrupt vectors; it might allow the submission
         * path to scale better, even if the receive path is limited by the
         * number of interrupts.
         */
        nr_io_queues = vecs;
        dev->max_qid = nr_io_queues;

        result = queue_request_irq(dev, adminq, adminq->irqname);
        if (result) {
                adminq->cq_vector = -1;
                goto free_queues;
        }
        return nvme_create_io_queues(dev);

 free_queues:
        nvme_free_queues(dev, 1);
        return result;
}

static void nvme_pci_post_scan(struct nvme_ctrl *ctrl)
{
        struct nvme_dev *dev = to_nvme_dev(ctrl);
        struct nvme_queue *nvmeq;
        int i;

        for (i = 0; i < dev->online_queues; i++) {
                nvmeq = dev->queues[i];

                if (!nvmeq->tags || !(*nvmeq->tags))
                        continue;

                irq_set_affinity_hint(dev->entry[nvmeq->cq_vector].vector,
                                        blk_mq_tags_cpumask(*nvmeq->tags));
        }
}

static void nvme_del_queue_end(struct request *req, int error)
{
        struct nvme_queue *nvmeq = req->end_io_data;

        blk_mq_free_request(req);
        complete(&nvmeq->dev->ioq_wait);
}

static void nvme_del_cq_end(struct request *req, int error)
{
        struct nvme_queue *nvmeq = req->end_io_data;

        if (!error) {
                unsigned long flags;

                /*
                 * We might be called with the AQ q_lock held
                 * and the I/O queue q_lock should always
                 * nest inside the AQ one.
                 */
                spin_lock_irqsave_nested(&nvmeq->q_lock, flags,
                                        SINGLE_DEPTH_NESTING);
                nvme_process_cq(nvmeq);
                spin_unlock_irqrestore(&nvmeq->q_lock, flags);
        }

        nvme_del_queue_end(req, error);
}

static int nvme_delete_queue(struct nvme_queue *nvmeq, u8 opcode)
{
        struct request_queue *q = nvmeq->dev->ctrl.admin_q;
        struct request *req;
        struct nvme_command cmd;

        memset(&cmd, 0, sizeof(cmd));
        cmd.delete_queue.opcode = opcode;
        cmd.delete_queue.qid = cpu_to_le16(nvmeq->qid);

        req = nvme_alloc_request(q, &cmd, BLK_MQ_REQ_NOWAIT);
        if (IS_ERR(req))
                return PTR_ERR(req);

        req->timeout = ADMIN_TIMEOUT;
        req->end_io_data = nvmeq;

        blk_execute_rq_nowait(q, NULL, req, false,
                        opcode == nvme_admin_delete_cq ?
                                nvme_del_cq_end : nvme_del_queue_end);
        return 0;
}

static void nvme_disable_io_queues(struct nvme_dev *dev)
{
        int pass, queues = dev->online_queues - 1;
        unsigned long timeout;
        u8 opcode = nvme_admin_delete_sq;

        for (pass = 0; pass < 2; pass++) {
                int sent = 0, i = queues;

                reinit_completion(&dev->ioq_wait);
 retry:
                timeout = ADMIN_TIMEOUT;
                for (; i > 0; i--) {
                        struct nvme_queue *nvmeq = dev->queues[i];

                        if (!pass)
                                nvme_suspend_queue(nvmeq);
                        if (nvme_delete_queue(nvmeq, opcode))
                                break;
                        ++sent;
                }
                while (sent--) {
                        timeout = wait_for_completion_io_timeout(&dev->ioq_wait, timeout);
                        if (timeout == 0)
                                return;
                        if (i)
                                goto retry;
                }
                opcode = nvme_admin_delete_cq;
        }
}

/*
 * Return: error value if an error occurred setting up the queues or calling
 * Identify Device.  0 if these succeeded, even if adding some of the
 * namespaces failed.  At the moment, these failures are silent.  TBD which
 * failures should be reported.
 */
static int nvme_dev_add(struct nvme_dev *dev)
{
        if (!dev->ctrl.tagset) {
                dev->tagset.ops = &nvme_mq_ops;
                dev->tagset.nr_hw_queues = dev->online_queues - 1;
                dev->tagset.timeout = NVME_IO_TIMEOUT;
                dev->tagset.numa_node = dev_to_node(dev->dev);
                dev->tagset.queue_depth =
                                min_t(int, dev->q_depth, BLK_MQ_MAX_DEPTH) - 1;
                dev->tagset.cmd_size = nvme_cmd_size(dev);
                dev->tagset.flags = BLK_MQ_F_SHOULD_MERGE;
                dev->tagset.driver_data = dev;

                if (blk_mq_alloc_tag_set(&dev->tagset))
                        return 0;
                dev->ctrl.tagset = &dev->tagset;
        } else {
                blk_mq_update_nr_hw_queues(&dev->tagset, dev->online_queues - 1);

                /* Free previously allocated queues that are no longer usable */
                nvme_free_queues(dev, dev->online_queues);
        }

        return 0;
}

static int nvme_pci_enable(struct nvme_dev *dev)
{
        u64 cap;
        int result = -ENOMEM;
        struct pci_dev *pdev = to_pci_dev(dev->dev);

        if (pci_enable_device_mem(pdev))
                return result;

        pci_set_master(pdev);

        if (dma_set_mask_and_coherent(dev->dev, DMA_BIT_MASK(64)) &&
            dma_set_mask_and_coherent(dev->dev, DMA_BIT_MASK(32)))
                goto disable;

        if (readl(dev->bar + NVME_REG_CSTS) == -1) {
                result = -ENODEV;
                goto disable;
        }

        /*
         * Some devices and/or platforms don't advertise or work with INTx
         * interrupts. Pre-enable a single MSIX or MSI vec for setup. We'll
         * adjust this later.
         */
        if (pci_enable_msix(pdev, dev->entry, 1)) {
                pci_enable_msi(pdev);
                dev->entry[0].vector = pdev->irq;
        }

        if (!dev->entry[0].vector) {
                result = -ENODEV;
                goto disable;
        }

        cap = lo_hi_readq(dev->bar + NVME_REG_CAP);

        dev->q_depth = min_t(int, NVME_CAP_MQES(cap) + 1, NVME_Q_DEPTH);
        dev->db_stride = 1 << NVME_CAP_STRIDE(cap);
        dev->dbs = dev->bar + 4096;

        /*
         * Temporary fix for the Apple controller found in the MacBook8,1 and
         * some MacBook7,1 to avoid controller resets and data loss.
         */
        if (pdev->vendor == PCI_VENDOR_ID_APPLE && pdev->device == 0x2001) {
                dev->q_depth = 2;
                dev_warn(dev->dev, "detected Apple NVMe controller, set "
                        "queue depth=%u to work around controller resets\n",
                        dev->q_depth);
        }

        if (readl(dev->bar + NVME_REG_VS) >= NVME_VS(1, 2))
                dev->cmb = nvme_map_cmb(dev);

        pci_enable_pcie_error_reporting(pdev);
        pci_save_state(pdev);
        return 0;

 disable:
        pci_disable_device(pdev);
        return result;
}

static void nvme_dev_unmap(struct nvme_dev *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev->dev);
        int bars;

        if (dev->bar)
                iounmap(dev->bar);

        bars = pci_select_bars(pdev, IORESOURCE_MEM);
        pci_release_selected_regions(pdev, bars);
}

static void nvme_pci_disable(struct nvme_dev *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev->dev);

        if (pdev->msi_enabled)
                pci_disable_msi(pdev);
        else if (pdev->msix_enabled)
                pci_disable_msix(pdev);

        if (pci_is_enabled(pdev)) {
                pci_disable_pcie_error_reporting(pdev);
                pci_disable_device(pdev);
        }
}

static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown)
{
        int i;
        u32 csts = -1;

        del_timer_sync(&dev->watchdog_timer);

        mutex_lock(&dev->shutdown_lock);
        if (pci_is_enabled(to_pci_dev(dev->dev))) {
                nvme_stop_queues(&dev->ctrl);
                csts = readl(dev->bar + NVME_REG_CSTS);
        }
        if (csts & NVME_CSTS_CFS || !(csts & NVME_CSTS_RDY)) {
                for (i = dev->queue_count - 1; i >= 0; i--) {
                        struct nvme_queue *nvmeq = dev->queues[i];
                        nvme_suspend_queue(nvmeq);
                }
        } else {
                nvme_disable_io_queues(dev);
                nvme_disable_admin_queue(dev, shutdown);
        }
        nvme_pci_disable(dev);

        blk_mq_tagset_busy_iter(&dev->tagset, nvme_cancel_io, dev);
        blk_mq_tagset_busy_iter(&dev->admin_tagset, nvme_cancel_io, dev);
        mutex_unlock(&dev->shutdown_lock);
}

static int nvme_setup_prp_pools(struct nvme_dev *dev)
{
        dev->prp_page_pool = dma_pool_create("prp list page", dev->dev,
                                                PAGE_SIZE, PAGE_SIZE, 0);
        if (!dev->prp_page_pool)
                return -ENOMEM;

        /* Optimisation for I/Os between 4k and 128k */
        dev->prp_small_pool = dma_pool_create("prp list 256", dev->dev,
                                                256, 256, 0);
        if (!dev->prp_small_pool) {
                dma_pool_destroy(dev->prp_page_pool);
                return -ENOMEM;
        }
        return 0;
}

static void nvme_release_prp_pools(struct nvme_dev *dev)
{
        dma_pool_destroy(dev->prp_page_pool);
        dma_pool_destroy(dev->prp_small_pool);
}

static void nvme_pci_free_ctrl(struct nvme_ctrl *ctrl)
{
        struct nvme_dev *dev = to_nvme_dev(ctrl);

        put_device(dev->dev);
        if (dev->tagset.tags)
                blk_mq_free_tag_set(&dev->tagset);
        if (dev->ctrl.admin_q)
                blk_put_queue(dev->ctrl.admin_q);
        kfree(dev->queues);
        kfree(dev->entry);
        kfree(dev);
}

static void nvme_remove_dead_ctrl(struct nvme_dev *dev, int status)
{
        dev_warn(dev->ctrl.device, "Removing after probe failure status: %d\n", status);

        kref_get(&dev->ctrl.kref);
        nvme_dev_disable(dev, false);
        if (!schedule_work(&dev->remove_work))
                nvme_put_ctrl(&dev->ctrl);
}

static void nvme_reset_work(struct work_struct *work)
{
        struct nvme_dev *dev = container_of(work, struct nvme_dev, reset_work);
        int result = -ENODEV;

        if (WARN_ON(dev->ctrl.state == NVME_CTRL_RESETTING))
                goto out;

        /*
         * If we're called to reset a live controller first shut it down before
         * moving on.
         */
        if (dev->ctrl.ctrl_config & NVME_CC_ENABLE)
                nvme_dev_disable(dev, false);

        if (!nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_RESETTING))
                goto out;

        result = nvme_pci_enable(dev);
        if (result)
                goto out;

        result = nvme_configure_admin_queue(dev);
        if (result)
                goto out;

        nvme_init_queue(dev->queues[0], 0);
        result = nvme_alloc_admin_tags(dev);
        if (result)
                goto out;

        result = nvme_init_identify(&dev->ctrl);
        if (result)
                goto out;

        result = nvme_setup_io_queues(dev);
        if (result)
                goto out;

        /*
         * A controller that can not execute IO typically requires user
         * intervention to correct. For such degraded controllers, the driver
         * should not submit commands the user did not request, so skip
         * registering for asynchronous event notification on this condition.
         */
        if (dev->online_queues > 1)
                nvme_queue_async_events(&dev->ctrl);

        mod_timer(&dev->watchdog_timer, round_jiffies(jiffies + HZ));

        /*
         * Keep the controller around but remove all namespaces if we don't have
         * any working I/O queue.
         */
        if (dev->online_queues < 2) {
                dev_warn(dev->ctrl.device, "IO queues not created\n");
                nvme_kill_queues(&dev->ctrl);
                nvme_remove_namespaces(&dev->ctrl);
        } else {
                nvme_start_queues(&dev->ctrl);
                nvme_dev_add(dev);
        }

        if (!nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_LIVE)) {
                dev_warn(dev->ctrl.device, "failed to mark controller live\n");
                goto out;
        }

        if (dev->online_queues > 1)
                nvme_queue_scan(&dev->ctrl);
        return;

 out:
        nvme_remove_dead_ctrl(dev, result);
}

static void nvme_remove_dead_ctrl_work(struct work_struct *work)
{
        struct nvme_dev *dev = container_of(work, struct nvme_dev, remove_work);
        struct pci_dev *pdev = to_pci_dev(dev->dev);

        nvme_kill_queues(&dev->ctrl);
        if (pci_get_drvdata(pdev))
                device_release_driver(&pdev->dev);
        nvme_put_ctrl(&dev->ctrl);
}

static int nvme_reset(struct nvme_dev *dev)
{
        if (!dev->ctrl.admin_q || blk_queue_dying(dev->ctrl.admin_q))
                return -ENODEV;

        if (!queue_work(nvme_workq, &dev->reset_work))
                return -EBUSY;

        flush_work(&dev->reset_work);
        return 0;
}

static int nvme_pci_reg_read32(struct nvme_ctrl *ctrl, u32 off, u32 *val)
{
        *val = readl(to_nvme_dev(ctrl)->bar + off);
        return 0;
}

static int nvme_pci_reg_write32(struct nvme_ctrl *ctrl, u32 off, u32 val)
{
        writel(val, to_nvme_dev(ctrl)->bar + off);
        return 0;
}

static int nvme_pci_reg_read64(struct nvme_ctrl *ctrl, u32 off, u64 *val)
{
        *val = readq(to_nvme_dev(ctrl)->bar + off);
        return 0;
}

static int nvme_pci_reset_ctrl(struct nvme_ctrl *ctrl)
{
        return nvme_reset(to_nvme_dev(ctrl));
}

static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = {
        .module                 = THIS_MODULE,
        .reg_read32             = nvme_pci_reg_read32,
        .reg_write32            = nvme_pci_reg_write32,
        .reg_read64             = nvme_pci_reg_read64,
        .reset_ctrl             = nvme_pci_reset_ctrl,
        .free_ctrl              = nvme_pci_free_ctrl,
        .post_scan              = nvme_pci_post_scan,
        .submit_async_event     = nvme_pci_submit_async_event,
};

static int nvme_dev_map(struct nvme_dev *dev)
{
        int bars;
        struct pci_dev *pdev = to_pci_dev(dev->dev);

        bars = pci_select_bars(pdev, IORESOURCE_MEM);
        if (!bars)
                return -ENODEV;
        if (pci_request_selected_regions(pdev, bars, "nvme"))
                return -ENODEV;

        dev->bar = ioremap(pci_resource_start(pdev, 0), 8192);
        if (!dev->bar)
                goto release;

       return 0;
  release:
       pci_release_selected_regions(pdev, bars);
       return -ENODEV;
}

static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
        int node, result = -ENOMEM;
        struct nvme_dev *dev;

        node = dev_to_node(&pdev->dev);
        if (node == NUMA_NO_NODE)
                set_dev_node(&pdev->dev, 0);

        dev = kzalloc_node(sizeof(*dev), GFP_KERNEL, node);
        if (!dev)
                return -ENOMEM;
        dev->entry = kzalloc_node(num_possible_cpus() * sizeof(*dev->entry),
                                                        GFP_KERNEL, node);
        if (!dev->entry)
                goto free;
        dev->queues = kzalloc_node((num_possible_cpus() + 1) * sizeof(void *),
                                                        GFP_KERNEL, node);
        if (!dev->queues)
                goto free;

        dev->dev = get_device(&pdev->dev);
        pci_set_drvdata(pdev, dev);

        result = nvme_dev_map(dev);
        if (result)
                goto free;

        INIT_WORK(&dev->reset_work, nvme_reset_work);
        INIT_WORK(&dev->remove_work, nvme_remove_dead_ctrl_work);
        setup_timer(&dev->watchdog_timer, nvme_watchdog_timer,
                (unsigned long)dev);
        mutex_init(&dev->shutdown_lock);
        init_completion(&dev->ioq_wait);

        result = nvme_setup_prp_pools(dev);
        if (result)
                goto put_pci;

        result = nvme_init_ctrl(&dev->ctrl, &pdev->dev, &nvme_pci_ctrl_ops,
                        id->driver_data);
        if (result)
                goto release_pools;

        dev_info(dev->ctrl.device, "pci function %s\n", dev_name(&pdev->dev));

        queue_work(nvme_workq, &dev->reset_work);
        return 0;

 release_pools:
        nvme_release_prp_pools(dev);
 put_pci:
        put_device(dev->dev);
        nvme_dev_unmap(dev);
 free:
        kfree(dev->queues);
        kfree(dev->entry);
        kfree(dev);
        return result;
}

static void nvme_reset_notify(struct pci_dev *pdev, bool prepare)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);

        if (prepare)
                nvme_dev_disable(dev, false);
        else
                queue_work(nvme_workq, &dev->reset_work);
}

static void nvme_shutdown(struct pci_dev *pdev)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);
        nvme_dev_disable(dev, true);
}

/*
 * The driver's remove may be called on a device in a partially initialized
 * state. This function must not have any dependencies on the device state in
 * order to proceed.
 */
static void nvme_remove(struct pci_dev *pdev)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);

        nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DELETING);

        pci_set_drvdata(pdev, NULL);

        if (!pci_device_is_present(pdev))
                nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DEAD);

        flush_work(&dev->reset_work);
        nvme_uninit_ctrl(&dev->ctrl);
        nvme_dev_disable(dev, true);
        nvme_dev_remove_admin(dev);
        nvme_free_queues(dev, 0);
        nvme_release_cmb(dev);
        nvme_release_prp_pools(dev);
        nvme_dev_unmap(dev);
        nvme_put_ctrl(&dev->ctrl);
}

#ifdef CONFIG_PM_SLEEP
static int nvme_suspend(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct nvme_dev *ndev = pci_get_drvdata(pdev);

        nvme_dev_disable(ndev, true);
        return 0;
}

static int nvme_resume(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct nvme_dev *ndev = pci_get_drvdata(pdev);

        queue_work(nvme_workq, &ndev->reset_work);
        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(nvme_dev_pm_ops, nvme_suspend, nvme_resume);

static pci_ers_result_t nvme_error_detected(struct pci_dev *pdev,
                                                pci_channel_state_t state)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);

        /*
         * A frozen channel requires a reset. When detected, this method will
         * shutdown the controller to quiesce. The controller will be restarted
         * after the slot reset through driver's slot_reset callback.
         */
        switch (state) {
        case pci_channel_io_normal:
                return PCI_ERS_RESULT_CAN_RECOVER;
        case pci_channel_io_frozen:
                dev_warn(dev->ctrl.device,
                        "frozen state error detected, reset controller\n");
                nvme_dev_disable(dev, false);
                return PCI_ERS_RESULT_NEED_RESET;
        case pci_channel_io_perm_failure:
                dev_warn(dev->ctrl.device,
                        "failure state error detected, request disconnect\n");
                return PCI_ERS_RESULT_DISCONNECT;
        }
        return PCI_ERS_RESULT_NEED_RESET;
}

static pci_ers_result_t nvme_slot_reset(struct pci_dev *pdev)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);

        dev_info(dev->ctrl.device, "restart after slot reset\n");
        pci_restore_state(pdev);
        queue_work(nvme_workq, &dev->reset_work);
        return PCI_ERS_RESULT_RECOVERED;
}

static void nvme_error_resume(struct pci_dev *pdev)
{
        pci_cleanup_aer_uncorrect_error_status(pdev);
}

static const struct pci_error_handlers nvme_err_handler = {
        .error_detected = nvme_error_detected,
        .slot_reset     = nvme_slot_reset,
        .resume         = nvme_error_resume,
        .reset_notify   = nvme_reset_notify,
};

/* Move to pci_ids.h later */
#define PCI_CLASS_STORAGE_EXPRESS       0x010802

static const struct pci_device_id nvme_id_table[] = {
        { PCI_VDEVICE(INTEL, 0x0953),
                .driver_data = NVME_QUIRK_STRIPE_SIZE |
                                NVME_QUIRK_DISCARD_ZEROES, },
        { PCI_VDEVICE(INTEL, 0x0a53),
                .driver_data = NVME_QUIRK_STRIPE_SIZE |
                                NVME_QUIRK_DISCARD_ZEROES, },
        { PCI_VDEVICE(INTEL, 0x0a54),
                .driver_data = NVME_QUIRK_STRIPE_SIZE |
                                NVME_QUIRK_DISCARD_ZEROES, },
        { PCI_VDEVICE(INTEL, 0x5845),   /* Qemu emulated controller */
                .driver_data = NVME_QUIRK_IDENTIFY_CNS, },
        { PCI_DEVICE_CLASS(PCI_CLASS_STORAGE_EXPRESS, 0xffffff) },
        { PCI_DEVICE(PCI_VENDOR_ID_APPLE, 0x2001) },
        { 0, }
};
MODULE_DEVICE_TABLE(pci, nvme_id_table);

static struct pci_driver nvme_driver = {
        .name           = "nvme",
        .id_table       = nvme_id_table,
        .probe          = nvme_probe,
        .remove         = nvme_remove,
        .shutdown       = nvme_shutdown,
        .driver         = {
                .pm     = &nvme_dev_pm_ops,
        },
        .err_handler    = &nvme_err_handler,
};

static int __init nvme_init(void)
{
        int result;

        nvme_workq = alloc_workqueue("nvme", WQ_UNBOUND | WQ_MEM_RECLAIM, 0);
        if (!nvme_workq)
                return -ENOMEM;

        result = pci_register_driver(&nvme_driver);
        if (result)
                destroy_workqueue(nvme_workq);
        return result;
}

static void __exit nvme_exit(void)
{
        pci_unregister_driver(&nvme_driver);
        destroy_workqueue(nvme_workq);
        _nvme_check_size();
}

MODULE_AUTHOR("Matthew Wilcox <willy@linux.intel.com>");
MODULE_LICENSE("GPL");
MODULE_VERSION("1.0");
module_init(nvme_init);
module_exit(nvme_exit);