// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for sTec s1120 PCIe SSDs. sTec was acquired in 2013 by HGST and HGST
 * was acquired by Western Digital in 2012.
 *
 * Copyright 2012 sTec, Inc.
 * Copyright (c) 2017 Western Digital Corporation or its affiliates.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/blkdev.h>
#include <linux/blk-mq.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/compiler.h>
#include <linux/workqueue.h>
#include <linux/delay.h>
#include <linux/time.h>
#include <linux/hdreg.h>
#include <linux/dma-mapping.h>
#include <linux/completion.h>
#include <linux/scatterlist.h>
#include <linux/err.h>
#include <linux/aer.h>
#include <linux/wait.h>
#include <linux/stringify.h>
#include <scsi/scsi.h>
#include <scsi/sg.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <asm/unaligned.h>

#include "skd_s1120.h"

static int skd_dbg_level;
static int skd_isr_comp_limit = 4;

#define SKD_ASSERT(expr) \
        do { \
                if (unlikely(!(expr))) { \
                        pr_err("Assertion failed! %s,%s,%s,line=%d\n",  \
                               # expr, __FILE__, __func__, __LINE__); \
                } \
        } while (0)

#define DRV_NAME "skd"
#define PFX DRV_NAME ": "

MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("STEC s1120 PCIe SSD block driver");

#define PCI_VENDOR_ID_STEC      0x1B39
#define PCI_DEVICE_ID_S1120     0x0001

#define SKD_FUA_NV              (1 << 1)
#define SKD_MINORS_PER_DEVICE   16

#define SKD_MAX_QUEUE_DEPTH     200u

#define SKD_PAUSE_TIMEOUT       (5 * 1000)

#define SKD_N_FITMSG_BYTES      (512u)
#define SKD_MAX_REQ_PER_MSG     14

#define SKD_N_SPECIAL_FITMSG_BYTES      (128u)

/* SG elements are 32 bytes, so we can make this 4096 and still be under the
 * 128KB limit.  That allows 4096*4K = 16M xfer size
 */
#define SKD_N_SG_PER_REQ_DEFAULT 256u

#define SKD_N_COMPLETION_ENTRY  256u
#define SKD_N_READ_CAP_BYTES    (8u)

#define SKD_N_INTERNAL_BYTES    (512u)

#define SKD_SKCOMP_SIZE                                                 \
        ((sizeof(struct fit_completion_entry_v1) +                      \
          sizeof(struct fit_comp_error_info)) * SKD_N_COMPLETION_ENTRY)

/* 5 bits of uniqifier, 0xF800 */
#define SKD_ID_TABLE_MASK       (3u << 8u)
#define  SKD_ID_RW_REQUEST      (0u << 8u)
#define  SKD_ID_INTERNAL        (1u << 8u)
#define  SKD_ID_FIT_MSG         (3u << 8u)
#define SKD_ID_SLOT_MASK        0x00FFu
#define SKD_ID_SLOT_AND_TABLE_MASK 0x03FFu

#define SKD_N_MAX_SECTORS 2048u

#define SKD_MAX_RETRIES 2u

#define SKD_TIMER_SECONDS(seconds) (seconds)
#define SKD_TIMER_MINUTES(minutes) ((minutes) * (60))

#define INQ_STD_NBYTES 36

enum skd_drvr_state {
        SKD_DRVR_STATE_LOAD,
        SKD_DRVR_STATE_IDLE,
        SKD_DRVR_STATE_BUSY,
        SKD_DRVR_STATE_STARTING,
        SKD_DRVR_STATE_ONLINE,
        SKD_DRVR_STATE_PAUSING,
        SKD_DRVR_STATE_PAUSED,
        SKD_DRVR_STATE_RESTARTING,
        SKD_DRVR_STATE_RESUMING,
        SKD_DRVR_STATE_STOPPING,
        SKD_DRVR_STATE_FAULT,
        SKD_DRVR_STATE_DISAPPEARED,
        SKD_DRVR_STATE_PROTOCOL_MISMATCH,
        SKD_DRVR_STATE_BUSY_ERASE,
        SKD_DRVR_STATE_BUSY_SANITIZE,
        SKD_DRVR_STATE_BUSY_IMMINENT,
        SKD_DRVR_STATE_WAIT_BOOT,
        SKD_DRVR_STATE_SYNCING,
};

#define SKD_WAIT_BOOT_TIMO      SKD_TIMER_SECONDS(90u)
#define SKD_STARTING_TIMO       SKD_TIMER_SECONDS(8u)
#define SKD_RESTARTING_TIMO     SKD_TIMER_MINUTES(4u)
#define SKD_BUSY_TIMO           SKD_TIMER_MINUTES(20u)
#define SKD_STARTED_BUSY_TIMO   SKD_TIMER_SECONDS(60u)
#define SKD_START_WAIT_SECONDS  90u

enum skd_req_state {
        SKD_REQ_STATE_IDLE,
        SKD_REQ_STATE_SETUP,
        SKD_REQ_STATE_BUSY,
        SKD_REQ_STATE_COMPLETED,
        SKD_REQ_STATE_TIMEOUT,
};

enum skd_check_status_action {
        SKD_CHECK_STATUS_REPORT_GOOD,
        SKD_CHECK_STATUS_REPORT_SMART_ALERT,
        SKD_CHECK_STATUS_REQUEUE_REQUEST,
        SKD_CHECK_STATUS_REPORT_ERROR,
        SKD_CHECK_STATUS_BUSY_IMMINENT,
};

struct skd_msg_buf {
        struct fit_msg_hdr      fmh;
        struct skd_scsi_request scsi[SKD_MAX_REQ_PER_MSG];
};

struct skd_fitmsg_context {
        u32 id;

        u32 length;

        struct skd_msg_buf *msg_buf;
        dma_addr_t mb_dma_address;
};

struct skd_request_context {
        enum skd_req_state state;

        u16 id;
        u32 fitmsg_id;

        u8 flush_cmd;

        enum dma_data_direction data_dir;
        struct scatterlist *sg;
        u32 n_sg;
        u32 sg_byte_count;

        struct fit_sg_descriptor *sksg_list;
        dma_addr_t sksg_dma_address;

        struct fit_completion_entry_v1 completion;

        struct fit_comp_error_info err_info;
        int retries;

        blk_status_t status;
};

struct skd_special_context {
        struct skd_request_context req;

        void *data_buf;
        dma_addr_t db_dma_address;

        struct skd_msg_buf *msg_buf;
        dma_addr_t mb_dma_address;
};

typedef enum skd_irq_type {
        SKD_IRQ_LEGACY,
        SKD_IRQ_MSI,
        SKD_IRQ_MSIX
} skd_irq_type_t;

#define SKD_MAX_BARS                    2

struct skd_device {
        void __iomem *mem_map[SKD_MAX_BARS];
        resource_size_t mem_phys[SKD_MAX_BARS];
        u32 mem_size[SKD_MAX_BARS];

        struct skd_msix_entry *msix_entries;

        struct pci_dev *pdev;
        int pcie_error_reporting_is_enabled;

        spinlock_t lock;
        struct gendisk *disk;
        struct blk_mq_tag_set tag_set;
        struct request_queue *queue;
        struct skd_fitmsg_context *skmsg;
        struct device *class_dev;
        int gendisk_on;
        int sync_done;

        u32 devno;
        u32 major;
        char isr_name[30];

        enum skd_drvr_state state;
        u32 drive_state;

        u32 cur_max_queue_depth;
        u32 queue_low_water_mark;
        u32 dev_max_queue_depth;

        u32 num_fitmsg_context;
        u32 num_req_context;

        struct skd_fitmsg_context *skmsg_table;

        struct skd_special_context internal_skspcl;
        u32 read_cap_blocksize;
        u32 read_cap_last_lba;
        int read_cap_is_valid;
        int inquiry_is_valid;
        u8 inq_serial_num[13];  /*12 chars plus null term */

        u8 skcomp_cycle;
        u32 skcomp_ix;
        struct kmem_cache *msgbuf_cache;
        struct kmem_cache *sglist_cache;
        struct kmem_cache *databuf_cache;
        struct fit_completion_entry_v1 *skcomp_table;
        struct fit_comp_error_info *skerr_table;
        dma_addr_t cq_dma_address;

        wait_queue_head_t waitq;

        struct timer_list timer;
        u32 timer_countdown;
        u32 timer_substate;

        int sgs_per_request;
        u32 last_mtd;

        u32 proto_ver;

        int dbg_level;
        u32 connect_time_stamp;
        int connect_retries;
#define SKD_MAX_CONNECT_RETRIES 16
        u32 drive_jiffies;

        u32 timo_slot;

        struct work_struct start_queue;
        struct work_struct completion_worker;
};

#define SKD_WRITEL(DEV, VAL, OFF) skd_reg_write32(DEV, VAL, OFF)
#define SKD_READL(DEV, OFF)      skd_reg_read32(DEV, OFF)
#define SKD_WRITEQ(DEV, VAL, OFF) skd_reg_write64(DEV, VAL, OFF)

static inline u32 skd_reg_read32(struct skd_device *skdev, u32 offset)
{
        u32 val = readl(skdev->mem_map[1] + offset);

        if (unlikely(skdev->dbg_level >= 2))
                dev_dbg(&skdev->pdev->dev, "offset %x = %x\n", offset, val);
        return val;
}

static inline void skd_reg_write32(struct skd_device *skdev, u32 val,
                                   u32 offset)
{
        writel(val, skdev->mem_map[1] + offset);
        if (unlikely(skdev->dbg_level >= 2))
                dev_dbg(&skdev->pdev->dev, "offset %x = %x\n", offset, val);
}

static inline void skd_reg_write64(struct skd_device *skdev, u64 val,
                                   u32 offset)
{
        writeq(val, skdev->mem_map[1] + offset);
        if (unlikely(skdev->dbg_level >= 2))
                dev_dbg(&skdev->pdev->dev, "offset %x = %016llx\n", offset,
                        val);
}


#define SKD_IRQ_DEFAULT SKD_IRQ_MSIX
static int skd_isr_type = SKD_IRQ_DEFAULT;

module_param(skd_isr_type, int, 0444);
MODULE_PARM_DESC(skd_isr_type, "Interrupt type capability."
                 " (0==legacy, 1==MSI, 2==MSI-X, default==1)");

#define SKD_MAX_REQ_PER_MSG_DEFAULT 1
static int skd_max_req_per_msg = SKD_MAX_REQ_PER_MSG_DEFAULT;

module_param(skd_max_req_per_msg, int, 0444);
MODULE_PARM_DESC(skd_max_req_per_msg,
                 "Maximum SCSI requests packed in a single message."
                 " (1-" __stringify(SKD_MAX_REQ_PER_MSG) ", default==1)");

#define SKD_MAX_QUEUE_DEPTH_DEFAULT 64
#define SKD_MAX_QUEUE_DEPTH_DEFAULT_STR "64"
static int skd_max_queue_depth = SKD_MAX_QUEUE_DEPTH_DEFAULT;

module_param(skd_max_queue_depth, int, 0444);
MODULE_PARM_DESC(skd_max_queue_depth,
                 "Maximum SCSI requests issued to s1120."
                 " (1-200, default==" SKD_MAX_QUEUE_DEPTH_DEFAULT_STR ")");

static int skd_sgs_per_request = SKD_N_SG_PER_REQ_DEFAULT;
module_param(skd_sgs_per_request, int, 0444);
MODULE_PARM_DESC(skd_sgs_per_request,
                 "Maximum SG elements per block request."
                 " (1-4096, default==256)");

static int skd_max_pass_thru = 1;
module_param(skd_max_pass_thru, int, 0444);
MODULE_PARM_DESC(skd_max_pass_thru,
                 "Maximum SCSI pass-thru at a time. IGNORED");

module_param(skd_dbg_level, int, 0444);
MODULE_PARM_DESC(skd_dbg_level, "s1120 debug level (0,1,2)");

module_param(skd_isr_comp_limit, int, 0444);
MODULE_PARM_DESC(skd_isr_comp_limit, "s1120 isr comp limit (0=none) default=4");

/* Major device number dynamically assigned. */
static u32 skd_major;

static void skd_destruct(struct skd_device *skdev);
static const struct block_device_operations skd_blockdev_ops;
static void skd_send_fitmsg(struct skd_device *skdev,
                            struct skd_fitmsg_context *skmsg);
static void skd_send_special_fitmsg(struct skd_device *skdev,
                                    struct skd_special_context *skspcl);
static bool skd_preop_sg_list(struct skd_device *skdev,
                             struct skd_request_context *skreq);
static void skd_postop_sg_list(struct skd_device *skdev,
                               struct skd_request_context *skreq);

static void skd_restart_device(struct skd_device *skdev);
static int skd_quiesce_dev(struct skd_device *skdev);
static int skd_unquiesce_dev(struct skd_device *skdev);
static void skd_disable_interrupts(struct skd_device *skdev);
static void skd_isr_fwstate(struct skd_device *skdev);
static void skd_recover_requests(struct skd_device *skdev);
static void skd_soft_reset(struct skd_device *skdev);

const char *skd_drive_state_to_str(int state);
const char *skd_skdev_state_to_str(enum skd_drvr_state state);
static void skd_log_skdev(struct skd_device *skdev, const char *event);
static void skd_log_skreq(struct skd_device *skdev,
                          struct skd_request_context *skreq, const char *event);

/*
 *****************************************************************************
 * READ/WRITE REQUESTS
 *****************************************************************************
 */
static bool skd_inc_in_flight(struct request *rq, void *data, bool reserved)
{
        int *count = data;

        count++;
        return true;
}

static int skd_in_flight(struct skd_device *skdev)
{
        int count = 0;

        blk_mq_tagset_busy_iter(&skdev->tag_set, skd_inc_in_flight, &count);

        return count;
}

static void
skd_prep_rw_cdb(struct skd_scsi_request *scsi_req,
                int data_dir, unsigned lba,
                unsigned count)
{
        if (data_dir == READ)
                scsi_req->cdb[0] = READ_10;
        else
                scsi_req->cdb[0] = WRITE_10;

        scsi_req->cdb[1] = 0;
        scsi_req->cdb[2] = (lba & 0xff000000) >> 24;
        scsi_req->cdb[3] = (lba & 0xff0000) >> 16;
        scsi_req->cdb[4] = (lba & 0xff00) >> 8;
        scsi_req->cdb[5] = (lba & 0xff);
        scsi_req->cdb[6] = 0;
        scsi_req->cdb[7] = (count & 0xff00) >> 8;
        scsi_req->cdb[8] = count & 0xff;
        scsi_req->cdb[9] = 0;
}

static void
skd_prep_zerosize_flush_cdb(struct skd_scsi_request *scsi_req,
                            struct skd_request_context *skreq)
{
        skreq->flush_cmd = 1;

        scsi_req->cdb[0] = SYNCHRONIZE_CACHE;
        scsi_req->cdb[1] = 0;
        scsi_req->cdb[2] = 0;
        scsi_req->cdb[3] = 0;
        scsi_req->cdb[4] = 0;
        scsi_req->cdb[5] = 0;
        scsi_req->cdb[6] = 0;
        scsi_req->cdb[7] = 0;
        scsi_req->cdb[8] = 0;
        scsi_req->cdb[9] = 0;
}

/*
 * Return true if and only if all pending requests should be failed.
 */
static bool skd_fail_all(struct request_queue *q)
{
        struct skd_device *skdev = q->queuedata;

        SKD_ASSERT(skdev->state != SKD_DRVR_STATE_ONLINE);

        skd_log_skdev(skdev, "req_not_online");
        switch (skdev->state) {
        case SKD_DRVR_STATE_PAUSING:
        case SKD_DRVR_STATE_PAUSED:
        case SKD_DRVR_STATE_STARTING:
        case SKD_DRVR_STATE_RESTARTING:
        case SKD_DRVR_STATE_WAIT_BOOT:
        /* In case of starting, we haven't started the queue,
         * so we can't get here... but requests are
         * possibly hanging out waiting for us because we
         * reported the dev/skd0 already.  They'll wait
         * forever if connect doesn't complete.
         * What to do??? delay dev/skd0 ??
         */
        case SKD_DRVR_STATE_BUSY:
        case SKD_DRVR_STATE_BUSY_IMMINENT:
        case SKD_DRVR_STATE_BUSY_ERASE:
                return false;

        case SKD_DRVR_STATE_BUSY_SANITIZE:
        case SKD_DRVR_STATE_STOPPING:
        case SKD_DRVR_STATE_SYNCING:
        case SKD_DRVR_STATE_FAULT:
        case SKD_DRVR_STATE_DISAPPEARED:
        default:
                return true;
        }
}

static blk_status_t skd_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
                                    const struct blk_mq_queue_data *mqd)
{
        struct request *const req = mqd->rq;
        struct request_queue *const q = req->q;
        struct skd_device *skdev = q->queuedata;
        struct skd_fitmsg_context *skmsg;
        struct fit_msg_hdr *fmh;
        const u32 tag = blk_mq_unique_tag(req);
        struct skd_request_context *const skreq = blk_mq_rq_to_pdu(req);
        struct skd_scsi_request *scsi_req;
        unsigned long flags = 0;
        const u32 lba = blk_rq_pos(req);
        const u32 count = blk_rq_sectors(req);
        const int data_dir = rq_data_dir(req);

        if (unlikely(skdev->state != SKD_DRVR_STATE_ONLINE))
                return skd_fail_all(q) ? BLK_STS_IOERR : BLK_STS_RESOURCE;

        if (!(req->rq_flags & RQF_DONTPREP)) {
                skreq->retries = 0;
                req->rq_flags |= RQF_DONTPREP;
        }

        blk_mq_start_request(req);

        WARN_ONCE(tag >= skd_max_queue_depth, "%#x > %#x (nr_requests = %lu)\n",
                  tag, skd_max_queue_depth, q->nr_requests);

        SKD_ASSERT(skreq->state == SKD_REQ_STATE_IDLE);

        dev_dbg(&skdev->pdev->dev,
                "new req=%p lba=%u(0x%x) count=%u(0x%x) dir=%d\n", req, lba,
                lba, count, count, data_dir);

        skreq->id = tag + SKD_ID_RW_REQUEST;
        skreq->flush_cmd = 0;
        skreq->n_sg = 0;
        skreq->sg_byte_count = 0;

        skreq->fitmsg_id = 0;

        skreq->data_dir = data_dir == READ ? DMA_FROM_DEVICE : DMA_TO_DEVICE;

        if (req->bio && !skd_preop_sg_list(skdev, skreq)) {
                dev_dbg(&skdev->pdev->dev, "error Out\n");
                skreq->status = BLK_STS_RESOURCE;
                blk_mq_complete_request(req);
                return BLK_STS_OK;
        }

        dma_sync_single_for_device(&skdev->pdev->dev, skreq->sksg_dma_address,
                                   skreq->n_sg *
                                   sizeof(struct fit_sg_descriptor),
                                   DMA_TO_DEVICE);

        /* Either a FIT msg is in progress or we have to start one. */
        if (skd_max_req_per_msg == 1) {
                skmsg = NULL;
        } else {
                spin_lock_irqsave(&skdev->lock, flags);
                skmsg = skdev->skmsg;
        }
        if (!skmsg) {
                skmsg = &skdev->skmsg_table[tag];
                skdev->skmsg = skmsg;

                /* Initialize the FIT msg header */
                fmh = &skmsg->msg_buf->fmh;
                memset(fmh, 0, sizeof(*fmh));
                fmh->protocol_id = FIT_PROTOCOL_ID_SOFIT;
                skmsg->length = sizeof(*fmh);
        } else {
                fmh = &skmsg->msg_buf->fmh;
        }

        skreq->fitmsg_id = skmsg->id;

        scsi_req = &skmsg->msg_buf->scsi[fmh->num_protocol_cmds_coalesced];
        memset(scsi_req, 0, sizeof(*scsi_req));

        scsi_req->hdr.tag = skreq->id;
        scsi_req->hdr.sg_list_dma_address =
                cpu_to_be64(skreq->sksg_dma_address);

        if (req_op(req) == REQ_OP_FLUSH) {
                skd_prep_zerosize_flush_cdb(scsi_req, skreq);
                SKD_ASSERT(skreq->flush_cmd == 1);
        } else {
                skd_prep_rw_cdb(scsi_req, data_dir, lba, count);
        }

        if (req->cmd_flags & REQ_FUA)
                scsi_req->cdb[1] |= SKD_FUA_NV;

        scsi_req->hdr.sg_list_len_bytes = cpu_to_be32(skreq->sg_byte_count);

        /* Complete resource allocations. */
        skreq->state = SKD_REQ_STATE_BUSY;

        skmsg->length += sizeof(struct skd_scsi_request);
        fmh->num_protocol_cmds_coalesced++;

        dev_dbg(&skdev->pdev->dev, "req=0x%x busy=%d\n", skreq->id,
                skd_in_flight(skdev));

        /*
         * If the FIT msg buffer is full send it.
         */
        if (skd_max_req_per_msg == 1) {
                skd_send_fitmsg(skdev, skmsg);
        } else {
                if (mqd->last ||
                    fmh->num_protocol_cmds_coalesced >= skd_max_req_per_msg) {
                        skd_send_fitmsg(skdev, skmsg);
                        skdev->skmsg = NULL;
                }
                spin_unlock_irqrestore(&skdev->lock, flags);
        }

        return BLK_STS_OK;
}

static enum blk_eh_timer_return skd_timed_out(struct request *req,
                                              bool reserved)
{
        struct skd_device *skdev = req->q->queuedata;

        dev_err(&skdev->pdev->dev, "request with tag %#x timed out\n",
                blk_mq_unique_tag(req));

        return BLK_EH_RESET_TIMER;
}

static void skd_complete_rq(struct request *req)
{
        struct skd_request_context *skreq = blk_mq_rq_to_pdu(req);

        blk_mq_end_request(req, skreq->status);
}

static bool skd_preop_sg_list(struct skd_device *skdev,
                             struct skd_request_context *skreq)
{
        struct request *req = blk_mq_rq_from_pdu(skreq);
        struct scatterlist *sgl = &skreq->sg[0], *sg;
        int n_sg;
        int i;

        skreq->sg_byte_count = 0;

        WARN_ON_ONCE(skreq->data_dir != DMA_TO_DEVICE &&
                     skreq->data_dir != DMA_FROM_DEVICE);

        n_sg = blk_rq_map_sg(skdev->queue, req, sgl);
        if (n_sg <= 0)
                return false;

        /*
         * Map scatterlist to PCI bus addresses.
         * Note PCI might change the number of entries.
         */
        n_sg = dma_map_sg(&skdev->pdev->dev, sgl, n_sg, skreq->data_dir);
        if (n_sg <= 0)
                return false;

        SKD_ASSERT(n_sg <= skdev->sgs_per_request);

        skreq->n_sg = n_sg;

        for_each_sg(sgl, sg, n_sg, i) {
                struct fit_sg_descriptor *sgd = &skreq->sksg_list[i];
                u32 cnt = sg_dma_len(sg);
                uint64_t dma_addr = sg_dma_address(sg);

                sgd->control = FIT_SGD_CONTROL_NOT_LAST;
                sgd->byte_count = cnt;
                skreq->sg_byte_count += cnt;
                sgd->host_side_addr = dma_addr;
                sgd->dev_side_addr = 0;
        }

        skreq->sksg_list[n_sg - 1].next_desc_ptr = 0LL;
        skreq->sksg_list[n_sg - 1].control = FIT_SGD_CONTROL_LAST;

        if (unlikely(skdev->dbg_level > 1)) {
                dev_dbg(&skdev->pdev->dev,
                        "skreq=%x sksg_list=%p sksg_dma=%pad\n",
                        skreq->id, skreq->sksg_list, &skreq->sksg_dma_address);
                for (i = 0; i < n_sg; i++) {
                        struct fit_sg_descriptor *sgd = &skreq->sksg_list[i];

                        dev_dbg(&skdev->pdev->dev,
                                "  sg[%d] count=%u ctrl=0x%x addr=0x%llx next=0x%llx\n",
                                i, sgd->byte_count, sgd->control,
                                sgd->host_side_addr, sgd->next_desc_ptr);
                }
        }

        return true;
}

static void skd_postop_sg_list(struct skd_device *skdev,
                               struct skd_request_context *skreq)
{
        /*
         * restore the next ptr for next IO request so we
         * don't have to set it every time.
         */
        skreq->sksg_list[skreq->n_sg - 1].next_desc_ptr =
                skreq->sksg_dma_address +
                ((skreq->n_sg) * sizeof(struct fit_sg_descriptor));
        dma_unmap_sg(&skdev->pdev->dev, &skreq->sg[0], skreq->n_sg,
                     skreq->data_dir);
}

/*
 *****************************************************************************
 * TIMER
 *****************************************************************************
 */

static void skd_timer_tick_not_online(struct skd_device *skdev);

static void skd_start_queue(struct work_struct *work)
{
        struct skd_device *skdev = container_of(work, typeof(*skdev),
                                                start_queue);

        /*
         * Although it is safe to call blk_start_queue() from interrupt
         * context, blk_mq_start_hw_queues() must not be called from
         * interrupt context.
         */
        blk_mq_start_hw_queues(skdev->queue);
}

static void skd_timer_tick(struct timer_list *t)
{
        struct skd_device *skdev = from_timer(skdev, t, timer);
        unsigned long reqflags;
        u32 state;

        if (skdev->state == SKD_DRVR_STATE_FAULT)
                /* The driver has declared fault, and we want it to
                 * stay that way until driver is reloaded.
                 */
                return;

        spin_lock_irqsave(&skdev->lock, reqflags);

        state = SKD_READL(skdev, FIT_STATUS);
        state &= FIT_SR_DRIVE_STATE_MASK;
        if (state != skdev->drive_state)
                skd_isr_fwstate(skdev);

        if (skdev->state != SKD_DRVR_STATE_ONLINE)
                skd_timer_tick_not_online(skdev);

        mod_timer(&skdev->timer, (jiffies + HZ));

        spin_unlock_irqrestore(&skdev->lock, reqflags);
}

static void skd_timer_tick_not_online(struct skd_device *skdev)
{
        switch (skdev->state) {
        case SKD_DRVR_STATE_IDLE:
        case SKD_DRVR_STATE_LOAD:
                break;
        case SKD_DRVR_STATE_BUSY_SANITIZE:
                dev_dbg(&skdev->pdev->dev,
                        "drive busy sanitize[%x], driver[%x]\n",
                        skdev->drive_state, skdev->state);
                /* If we've been in sanitize for 3 seconds, we figure we're not
                 * going to get anymore completions, so recover requests now
                 */
                if (skdev->timer_countdown > 0) {
                        skdev->timer_countdown--;
                        return;
                }
                skd_recover_requests(skdev);
                break;

        case SKD_DRVR_STATE_BUSY:
        case SKD_DRVR_STATE_BUSY_IMMINENT:
        case SKD_DRVR_STATE_BUSY_ERASE:
                dev_dbg(&skdev->pdev->dev, "busy[%x], countdown=%d\n",
                        skdev->state, skdev->timer_countdown);
                if (skdev->timer_countdown > 0) {
                        skdev->timer_countdown--;
                        return;
                }
                dev_dbg(&skdev->pdev->dev,
                        "busy[%x], timedout=%d, restarting device.",
                        skdev->state, skdev->timer_countdown);
                skd_restart_device(skdev);
                break;

        case SKD_DRVR_STATE_WAIT_BOOT:
        case SKD_DRVR_STATE_STARTING:
                if (skdev->timer_countdown > 0) {
                        skdev->timer_countdown--;
                        return;
                }
                /* For now, we fault the drive.  Could attempt resets to
                 * revcover at some point. */
                skdev->state = SKD_DRVR_STATE_FAULT;

                dev_err(&skdev->pdev->dev, "DriveFault Connect Timeout (%x)\n",
                        skdev->drive_state);

                /*start the queue so we can respond with error to requests */
                /* wakeup anyone waiting for startup complete */
                schedule_work(&skdev->start_queue);
                skdev->gendisk_on = -1;
                wake_up_interruptible(&skdev->waitq);
                break;

        case SKD_DRVR_STATE_ONLINE:
                /* shouldn't get here. */
                break;

        case SKD_DRVR_STATE_PAUSING:
        case SKD_DRVR_STATE_PAUSED:
                break;

        case SKD_DRVR_STATE_RESTARTING:
                if (skdev->timer_countdown > 0) {
                        skdev->timer_countdown--;
                        return;
                }
                /* For now, we fault the drive. Could attempt resets to
                 * revcover at some point. */
                skdev->state = SKD_DRVR_STATE_FAULT;
                dev_err(&skdev->pdev->dev,
                        "DriveFault Reconnect Timeout (%x)\n",
                        skdev->drive_state);

                /*
                 * Recovering does two things:
                 * 1. completes IO with error
                 * 2. reclaims dma resources
                 * When is it safe to recover requests?
                 * - if the drive state is faulted
                 * - if the state is still soft reset after out timeout
                 * - if the drive registers are dead (state = FF)
                 * If it is "unsafe", we still need to recover, so we will
                 * disable pci bus mastering and disable our interrupts.
                 */

                if ((skdev->drive_state == FIT_SR_DRIVE_SOFT_RESET) ||
                    (skdev->drive_state == FIT_SR_DRIVE_FAULT) ||
                    (skdev->drive_state == FIT_SR_DRIVE_STATE_MASK))
                        /* It never came out of soft reset. Try to
                         * recover the requests and then let them
                         * fail. This is to mitigate hung processes. */
                        skd_recover_requests(skdev);
                else {
                        dev_err(&skdev->pdev->dev, "Disable BusMaster (%x)\n",
                                skdev->drive_state);
                        pci_disable_device(skdev->pdev);
                        skd_disable_interrupts(skdev);
                        skd_recover_requests(skdev);
                }

                /*start the queue so we can respond with error to requests */
                /* wakeup anyone waiting for startup complete */
                schedule_work(&skdev->start_queue);
                skdev->gendisk_on = -1;
                wake_up_interruptible(&skdev->waitq);
                break;

        case SKD_DRVR_STATE_RESUMING:
        case SKD_DRVR_STATE_STOPPING:
        case SKD_DRVR_STATE_SYNCING:
        case SKD_DRVR_STATE_FAULT:
        case SKD_DRVR_STATE_DISAPPEARED:
        default:
                break;
        }
}

static int skd_start_timer(struct skd_device *skdev)
{
        int rc;

        timer_setup(&skdev->timer, skd_timer_tick, 0);

        rc = mod_timer(&skdev->timer, (jiffies + HZ));
        if (rc)
                dev_err(&skdev->pdev->dev, "failed to start timer %d\n", rc);
        return rc;
}

static void skd_kill_timer(struct skd_device *skdev)
{
        del_timer_sync(&skdev->timer);
}

/*
 *****************************************************************************
 * INTERNAL REQUESTS -- generated by driver itself
 *****************************************************************************
 */

static int skd_format_internal_skspcl(struct skd_device *skdev)
{
        struct skd_special_context *skspcl = &skdev->internal_skspcl;
        struct fit_sg_descriptor *sgd = &skspcl->req.sksg_list[0];
        struct fit_msg_hdr *fmh;
        uint64_t dma_address;
        struct skd_scsi_request *scsi;

        fmh = &skspcl->msg_buf->fmh;
        fmh->protocol_id = FIT_PROTOCOL_ID_SOFIT;
        fmh->num_protocol_cmds_coalesced = 1;

        scsi = &skspcl->msg_buf->scsi[0];
        memset(scsi, 0, sizeof(*scsi));
        dma_address = skspcl->req.sksg_dma_address;
        scsi->hdr.sg_list_dma_address = cpu_to_be64(dma_address);
        skspcl->req.n_sg = 1;
        sgd->control = FIT_SGD_CONTROL_LAST;
        sgd->byte_count = 0;
        sgd->host_side_addr = skspcl->db_dma_address;
        sgd->dev_side_addr = 0;
        sgd->next_desc_ptr = 0LL;

        return 1;
}

#define WR_BUF_SIZE SKD_N_INTERNAL_BYTES

static void skd_send_internal_skspcl(struct skd_device *skdev,
                                     struct skd_special_context *skspcl,
                                     u8 opcode)
{
        struct fit_sg_descriptor *sgd = &skspcl->req.sksg_list[0];
        struct skd_scsi_request *scsi;
        unsigned char *buf = skspcl->data_buf;
        int i;

        if (skspcl->req.state != SKD_REQ_STATE_IDLE)
                /*
                 * A refresh is already in progress.
                 * Just wait for it to finish.
                 */
                return;

        skspcl->req.state = SKD_REQ_STATE_BUSY;

        scsi = &skspcl->msg_buf->scsi[0];
        scsi->hdr.tag = skspcl->req.id;

        memset(scsi->cdb, 0, sizeof(scsi->cdb));

        switch (opcode) {
        case TEST_UNIT_READY:
                scsi->cdb[0] = TEST_UNIT_READY;
                sgd->byte_count = 0;
                scsi->hdr.sg_list_len_bytes = 0;
                break;

        case READ_CAPACITY:
                scsi->cdb[0] = READ_CAPACITY;
                sgd->byte_count = SKD_N_READ_CAP_BYTES;
                scsi->hdr.sg_list_len_bytes = cpu_to_be32(sgd->byte_count);
                break;

        case INQUIRY:
                scsi->cdb[0] = INQUIRY;
                scsi->cdb[1] = 0x01;    /* evpd */
                scsi->cdb[2] = 0x80;    /* serial number page */
                scsi->cdb[4] = 0x10;
                sgd->byte_count = 16;
                scsi->hdr.sg_list_len_bytes = cpu_to_be32(sgd->byte_count);
                break;

        case SYNCHRONIZE_CACHE:
                scsi->cdb[0] = SYNCHRONIZE_CACHE;
                sgd->byte_count = 0;
                scsi->hdr.sg_list_len_bytes = 0;
                break;

        case WRITE_BUFFER:
                scsi->cdb[0] = WRITE_BUFFER;
                scsi->cdb[1] = 0x02;
                scsi->cdb[7] = (WR_BUF_SIZE & 0xFF00) >> 8;
                scsi->cdb[8] = WR_BUF_SIZE & 0xFF;
                sgd->byte_count = WR_BUF_SIZE;
                scsi->hdr.sg_list_len_bytes = cpu_to_be32(sgd->byte_count);
                /* fill incrementing byte pattern */
                for (i = 0; i < sgd->byte_count; i++)
                        buf[i] = i & 0xFF;
                break;

        case READ_BUFFER:
                scsi->cdb[0] = READ_BUFFER;
                scsi->cdb[1] = 0x02;
                scsi->cdb[7] = (WR_BUF_SIZE & 0xFF00) >> 8;
                scsi->cdb[8] = WR_BUF_SIZE & 0xFF;
                sgd->byte_count = WR_BUF_SIZE;
                scsi->hdr.sg_list_len_bytes = cpu_to_be32(sgd->byte_count);
                memset(skspcl->data_buf, 0, sgd->byte_count);
                break;

        default:
                SKD_ASSERT("Don't know what to send");
                return;

        }
        skd_send_special_fitmsg(skdev, skspcl);
}

static void skd_refresh_device_data(struct skd_device *skdev)
{
        struct skd_special_context *skspcl = &skdev->internal_skspcl;

        skd_send_internal_skspcl(skdev, skspcl, TEST_UNIT_READY);
}

static int skd_chk_read_buf(struct skd_device *skdev,
                            struct skd_special_context *skspcl)

{
        unsigned char *buf = skspcl->data_buf;
        int i;

        /* check for incrementing byte pattern */
        for (i = 0; i < WR_BUF_SIZE; i++)
                if (buf[i] != (i & 0xFF))
                        return 1;

        return 0;
}

static void skd_log_check_status(struct skd_device *skdev, u8 status, u8 key,
                                 u8 code, u8 qual, u8 fruc)
{
        /* If the check condition is of special interest, log a message */
        if ((status == SAM_STAT_CHECK_CONDITION) && (key == 0x02)
            && (code == 0x04) && (qual == 0x06)) {
                dev_err(&skdev->pdev->dev,
                        "*** LOST_WRITE_DATA ERROR *** key/asc/ascq/fruc %02x/%02x/%02x/%02x\n",
                        key, code, qual, fruc);
        }
}

static void skd_complete_internal(struct skd_device *skdev,
                                  struct fit_completion_entry_v1 *skcomp,
                                  struct fit_comp_error_info *skerr,
                                  struct skd_special_context *skspcl)
{
        u8 *buf = skspcl->data_buf;
        u8 status;
        int i;
        struct skd_scsi_request *scsi = &skspcl->msg_buf->scsi[0];

        lockdep_assert_held(&skdev->lock);

        SKD_ASSERT(skspcl == &skdev->internal_skspcl);

        dev_dbg(&skdev->pdev->dev, "complete internal %x\n", scsi->cdb[0]);

        dma_sync_single_for_cpu(&skdev->pdev->dev,
                                skspcl->db_dma_address,
                                skspcl->req.sksg_list[0].byte_count,
                                DMA_BIDIRECTIONAL);

        skspcl->req.completion = *skcomp;
        skspcl->req.state = SKD_REQ_STATE_IDLE;

        status = skspcl->req.completion.status;

        skd_log_check_status(skdev, status, skerr->key, skerr->code,
                             skerr->qual, skerr->fruc);

        switch (scsi->cdb[0]) {
        case TEST_UNIT_READY:
                if (status == SAM_STAT_GOOD)
                        skd_send_internal_skspcl(skdev, skspcl, WRITE_BUFFER);
                else if ((status == SAM_STAT_CHECK_CONDITION) &&
                         (skerr->key == MEDIUM_ERROR))
                        skd_send_internal_skspcl(skdev, skspcl, WRITE_BUFFER);
                else {
                        if (skdev->state == SKD_DRVR_STATE_STOPPING) {
                                dev_dbg(&skdev->pdev->dev,
                                        "TUR failed, don't send anymore state 0x%x\n",
                                        skdev->state);
                                return;
                        }
                        dev_dbg(&skdev->pdev->dev,
                                "**** TUR failed, retry skerr\n");
                        skd_send_internal_skspcl(skdev, skspcl,
                                                 TEST_UNIT_READY);
                }
                break;

        case WRITE_BUFFER:
                if (status == SAM_STAT_GOOD)
                        skd_send_internal_skspcl(skdev, skspcl, READ_BUFFER);
                else {
                        if (skdev->state == SKD_DRVR_STATE_STOPPING) {
                                dev_dbg(&skdev->pdev->dev,
                                        "write buffer failed, don't send anymore state 0x%x\n",
                                        skdev->state);
                                return;
                        }
                        dev_dbg(&skdev->pdev->dev,
                                "**** write buffer failed, retry skerr\n");
                        skd_send_internal_skspcl(skdev, skspcl,
                                                 TEST_UNIT_READY);
                }
                break;

        case READ_BUFFER:
                if (status == SAM_STAT_GOOD) {
                        if (skd_chk_read_buf(skdev, skspcl) == 0)
                                skd_send_internal_skspcl(skdev, skspcl,
                                                         READ_CAPACITY);
                        else {
                                dev_err(&skdev->pdev->dev,
                                        "*** W/R Buffer mismatch %d ***\n",
                                        skdev->connect_retries);
                                if (skdev->connect_retries <
                                    SKD_MAX_CONNECT_RETRIES) {
                                        skdev->connect_retries++;
                                        skd_soft_reset(skdev);
                                } else {
                                        dev_err(&skdev->pdev->dev,
                                                "W/R Buffer Connect Error\n");
                                        return;
                                }
                        }

                } else {
                        if (skdev->state == SKD_DRVR_STATE_STOPPING) {
                                dev_dbg(&skdev->pdev->dev,
                                        "read buffer failed, don't send anymore state 0x%x\n",
                                        skdev->state);
                                return;
                        }
                        dev_dbg(&skdev->pdev->dev,
                                "**** read buffer failed, retry skerr\n");
                        skd_send_internal_skspcl(skdev, skspcl,
                                                 TEST_UNIT_READY);
                }
                break;

        case READ_CAPACITY:
                skdev->read_cap_is_valid = 0;
                if (status == SAM_STAT_GOOD) {
                        skdev->read_cap_last_lba =
                                (buf[0] << 24) | (buf[1] << 16) |
                                (buf[2] << 8) | buf[3];
                        skdev->read_cap_blocksize =
                                (buf[4] << 24) | (buf[5] << 16) |
                                (buf[6] << 8) | buf[7];

                        dev_dbg(&skdev->pdev->dev, "last lba %d, bs %d\n",
                                skdev->read_cap_last_lba,
                                skdev->read_cap_blocksize);

                        set_capacity(skdev->disk, skdev->read_cap_last_lba + 1);

                        skdev->read_cap_is_valid = 1;

                        skd_send_internal_skspcl(skdev, skspcl, INQUIRY);
                } else if ((status == SAM_STAT_CHECK_CONDITION) &&
                           (skerr->key == MEDIUM_ERROR)) {
                        skdev->read_cap_last_lba = ~0;
                        set_capacity(skdev->disk, skdev->read_cap_last_lba + 1);
                        dev_dbg(&skdev->pdev->dev, "**** MEDIUM ERROR caused READCAP to fail, ignore failure and continue to inquiry\n");
                        skd_send_internal_skspcl(skdev, skspcl, INQUIRY);
                } else {
                        dev_dbg(&skdev->pdev->dev, "**** READCAP failed, retry TUR\n");
                        skd_send_internal_skspcl(skdev, skspcl,
                                                 TEST_UNIT_READY);
                }
                break;

        case INQUIRY:
                skdev->inquiry_is_valid = 0;
                if (status == SAM_STAT_GOOD) {
                        skdev->inquiry_is_valid = 1;

                        for (i = 0; i < 12; i++)
                                skdev->inq_serial_num[i] = buf[i + 4];
                        skdev->inq_serial_num[12] = 0;
                }

                if (skd_unquiesce_dev(skdev) < 0)
                        dev_dbg(&skdev->pdev->dev, "**** failed, to ONLINE device\n");
                 /* connection is complete */
                skdev->connect_retries = 0;
                break;

        case SYNCHRONIZE_CACHE:
                if (status == SAM_STAT_GOOD)
                        skdev->sync_done = 1;
                else
                        skdev->sync_done = -1;
                wake_up_interruptible(&skdev->waitq);
                break;

        default:
                SKD_ASSERT("we didn't send this");
        }
}

/*
 *****************************************************************************
 * FIT MESSAGES
 *****************************************************************************
 */

static void skd_send_fitmsg(struct skd_device *skdev,
                            struct skd_fitmsg_context *skmsg)
{
        u64 qcmd;

        dev_dbg(&skdev->pdev->dev, "dma address %pad, busy=%d\n",
                &skmsg->mb_dma_address, skd_in_flight(skdev));
        dev_dbg(&skdev->pdev->dev, "msg_buf %p\n", skmsg->msg_buf);

        qcmd = skmsg->mb_dma_address;
        qcmd |= FIT_QCMD_QID_NORMAL;

        if (unlikely(skdev->dbg_level > 1)) {
                u8 *bp = (u8 *)skmsg->msg_buf;
                int i;
                for (i = 0; i < skmsg->length; i += 8) {
                        dev_dbg(&skdev->pdev->dev, "msg[%2d] %8ph\n", i,
                                &bp[i]);
                        if (i == 0)
                                i = 64 - 8;
                }
        }

        if (skmsg->length > 256)
                qcmd |= FIT_QCMD_MSGSIZE_512;
        else if (skmsg->length > 128)
                qcmd |= FIT_QCMD_MSGSIZE_256;
        else if (skmsg->length > 64)
                qcmd |= FIT_QCMD_MSGSIZE_128;
        else
                /*
                 * This makes no sense because the FIT msg header is
                 * 64 bytes. If the msg is only 64 bytes long it has
                 * no payload.
                 */
                qcmd |= FIT_QCMD_MSGSIZE_64;

        dma_sync_single_for_device(&skdev->pdev->dev, skmsg->mb_dma_address,
                                   skmsg->length, DMA_TO_DEVICE);

        /* Make sure skd_msg_buf is written before the doorbell is triggered. */
        smp_wmb();

        SKD_WRITEQ(skdev, qcmd, FIT_Q_COMMAND);
}

static void skd_send_special_fitmsg(struct skd_device *skdev,
                                    struct skd_special_context *skspcl)
{
        u64 qcmd;

        WARN_ON_ONCE(skspcl->req.n_sg != 1);

        if (unlikely(skdev->dbg_level > 1)) {
                u8 *bp = (u8 *)skspcl->msg_buf;
                int i;

                for (i = 0; i < SKD_N_SPECIAL_FITMSG_BYTES; i += 8) {
                        dev_dbg(&skdev->pdev->dev, " spcl[%2d] %8ph\n", i,
                                &bp[i]);
                        if (i == 0)
                                i = 64 - 8;
                }

                dev_dbg(&skdev->pdev->dev,
                        "skspcl=%p id=%04x sksg_list=%p sksg_dma=%pad\n",
                        skspcl, skspcl->req.id, skspcl->req.sksg_list,
                        &skspcl->req.sksg_dma_address);
                for (i = 0; i < skspcl->req.n_sg; i++) {
                        struct fit_sg_descriptor *sgd =
                                &skspcl->req.sksg_list[i];

                        dev_dbg(&skdev->pdev->dev,
                                "  sg[%d] count=%u ctrl=0x%x addr=0x%llx next=0x%llx\n",
                                i, sgd->byte_count, sgd->control,
                                sgd->host_side_addr, sgd->next_desc_ptr);
                }
        }

        /*
         * Special FIT msgs are always 128 bytes: a 64-byte FIT hdr
         * and one 64-byte SSDI command.
         */
        qcmd = skspcl->mb_dma_address;
        qcmd |= FIT_QCMD_QID_NORMAL + FIT_QCMD_MSGSIZE_128;

        dma_sync_single_for_device(&skdev->pdev->dev, skspcl->mb_dma_address,
                                   SKD_N_SPECIAL_FITMSG_BYTES, DMA_TO_DEVICE);
        dma_sync_single_for_device(&skdev->pdev->dev,
                                   skspcl->req.sksg_dma_address,
                                   1 * sizeof(struct fit_sg_descriptor),
                                   DMA_TO_DEVICE);
        dma_sync_single_for_device(&skdev->pdev->dev,
                                   skspcl->db_dma_address,
                                   skspcl->req.sksg_list[0].byte_count,
                                   DMA_BIDIRECTIONAL);

        /* Make sure skd_msg_buf is written before the doorbell is triggered. */
        smp_wmb();

        SKD_WRITEQ(skdev, qcmd, FIT_Q_COMMAND);
}

/*
 *****************************************************************************
 * COMPLETION QUEUE
 *****************************************************************************
 */

static void skd_complete_other(struct skd_device *skdev,
                               struct fit_completion_entry_v1 *skcomp,
                               struct fit_comp_error_info *skerr);

struct sns_info {
        u8 type;
        u8 stat;
        u8 key;
        u8 asc;
        u8 ascq;
        u8 mask;
        enum skd_check_status_action action;
};

static struct sns_info skd_chkstat_table[] = {
        /* Good */
        { 0x70, 0x02, RECOVERED_ERROR, 0,    0,    0x1c,
          SKD_CHECK_STATUS_REPORT_GOOD },

        /* Smart alerts */
        { 0x70, 0x02, NO_SENSE,        0x0B, 0x00, 0x1E,        /* warnings */
          SKD_CHECK_STATUS_REPORT_SMART_ALERT },
        { 0x70, 0x02, NO_SENSE,        0x5D, 0x00, 0x1E,        /* thresholds */
          SKD_CHECK_STATUS_REPORT_SMART_ALERT },
        { 0x70, 0x02, RECOVERED_ERROR, 0x0B, 0x01, 0x1F,        /* temperature over trigger */
          SKD_CHECK_STATUS_REPORT_SMART_ALERT },

        /* Retry (with limits) */
        { 0x70, 0x02, 0x0B,            0,    0,    0x1C,        /* This one is for DMA ERROR */
          SKD_CHECK_STATUS_REQUEUE_REQUEST },
        { 0x70, 0x02, 0x06,            0x0B, 0x00, 0x1E,        /* warnings */
          SKD_CHECK_STATUS_REQUEUE_REQUEST },
        { 0x70, 0x02, 0x06,            0x5D, 0x00, 0x1E,        /* thresholds */
          SKD_CHECK_STATUS_REQUEUE_REQUEST },
        { 0x70, 0x02, 0x06,            0x80, 0x30, 0x1F,        /* backup power */
          SKD_CHECK_STATUS_REQUEUE_REQUEST },

        /* Busy (or about to be) */
        { 0x70, 0x02, 0x06,            0x3f, 0x01, 0x1F, /* fw changed */
          SKD_CHECK_STATUS_BUSY_IMMINENT },
};

/*
 * Look up status and sense data to decide how to handle the error
 * from the device.
 * mask says which fields must match e.g., mask=0x18 means check
 * type and stat, ignore key, asc, ascq.
 */

static enum skd_check_status_action
skd_check_status(struct skd_device *skdev,
                 u8 cmp_status, struct fit_comp_error_info *skerr)
{
        int i;

        dev_err(&skdev->pdev->dev, "key/asc/ascq/fruc %02x/%02x/%02x/%02x\n",
                skerr->key, skerr->code, skerr->qual, skerr->fruc);

        dev_dbg(&skdev->pdev->dev,
                "stat: t=%02x stat=%02x k=%02x c=%02x q=%02x fruc=%02x\n",
                skerr->type, cmp_status, skerr->key, skerr->code, skerr->qual,
                skerr->fruc);

        /* Does the info match an entry in the good category? */
        for (i = 0; i < ARRAY_SIZE(skd_chkstat_table); i++) {
                struct sns_info *sns = &skd_chkstat_table[i];

                if (sns->mask & 0x10)
                        if (skerr->type != sns->type)
                                continue;

                if (sns->mask & 0x08)
                        if (cmp_status != sns->stat)
                                continue;

                if (sns->mask & 0x04)
                        if (skerr->key != sns->key)
                                continue;

                if (sns->mask & 0x02)
                        if (skerr->code != sns->asc)
                                continue;

                if (sns->mask & 0x01)
                        if (skerr->qual != sns->ascq)
                                continue;

                if (sns->action == SKD_CHECK_STATUS_REPORT_SMART_ALERT) {
                        dev_err(&skdev->pdev->dev,
                                "SMART Alert: sense key/asc/ascq %02x/%02x/%02x\n",
                                skerr->key, skerr->code, skerr->qual);
                }
                return sns->action;
        }

        /* No other match, so nonzero status means error,
         * zero status means good
         */
        if (cmp_status) {
                dev_dbg(&skdev->pdev->dev, "status check: error\n");
                return SKD_CHECK_STATUS_REPORT_ERROR;
        }

        dev_dbg(&skdev->pdev->dev, "status check good default\n");
        return SKD_CHECK_STATUS_REPORT_GOOD;
}

static void skd_resolve_req_exception(struct skd_device *skdev,
                                      struct skd_request_context *skreq,
                                      struct request *req)
{
        u8 cmp_status = skreq->completion.status;

        switch (skd_check_status(skdev, cmp_status, &skreq->err_info)) {
        case SKD_CHECK_STATUS_REPORT_GOOD:
        case SKD_CHECK_STATUS_REPORT_SMART_ALERT:
                skreq->status = BLK_STS_OK;
                if (likely(!blk_should_fake_timeout(req->q)))
                        blk_mq_complete_request(req);
                break;

        case SKD_CHECK_STATUS_BUSY_IMMINENT:
                skd_log_skreq(skdev, skreq, "retry(busy)");
                blk_mq_requeue_request(req, true);
                dev_info(&skdev->pdev->dev, "drive BUSY imminent\n");
                skdev->state = SKD_DRVR_STATE_BUSY_IMMINENT;
                skdev->timer_countdown = SKD_TIMER_MINUTES(20);
                skd_quiesce_dev(skdev);
                break;

        case SKD_CHECK_STATUS_REQUEUE_REQUEST:
                if (++skreq->retries < SKD_MAX_RETRIES) {
                        skd_log_skreq(skdev, skreq, "retry");
                        blk_mq_requeue_request(req, true);
                        break;
                }
                fallthrough;

        case SKD_CHECK_STATUS_REPORT_ERROR:
        default:
                skreq->status = BLK_STS_IOERR;
                if (likely(!blk_should_fake_timeout(req->q)))
                        blk_mq_complete_request(req);
                break;
        }
}

static void skd_release_skreq(struct skd_device *skdev,
                              struct skd_request_context *skreq)
{
        /*
         * Reclaim the skd_request_context
         */
        skreq->state = SKD_REQ_STATE_IDLE;
}

static int skd_isr_completion_posted(struct skd_device *skdev,
                                        int limit, int *enqueued)
{
        struct fit_completion_entry_v1 *skcmp;
        struct fit_comp_error_info *skerr;
        u16 req_id;
        u32 tag;
        u16 hwq = 0;
        struct request *rq;
        struct skd_request_context *skreq;
        u16 cmp_cntxt;
        u8 cmp_status;
        u8 cmp_cycle;
        u32 cmp_bytes;
        int rc = 0;
        int processed = 0;

        lockdep_assert_held(&skdev->lock);

        for (;; ) {
                SKD_ASSERT(skdev->skcomp_ix < SKD_N_COMPLETION_ENTRY);

                skcmp = &skdev->skcomp_table[skdev->skcomp_ix];
                cmp_cycle = skcmp->cycle;
                cmp_cntxt = skcmp->tag;
                cmp_status = skcmp->status;
                cmp_bytes = be32_to_cpu(skcmp->num_returned_bytes);

                skerr = &skdev->skerr_table[skdev->skcomp_ix];

                dev_dbg(&skdev->pdev->dev,
                        "cycle=%d ix=%d got cycle=%d cmdctxt=0x%x stat=%d busy=%d rbytes=0x%x proto=%d\n",
                        skdev->skcomp_cycle, skdev->skcomp_ix, cmp_cycle,
                        cmp_cntxt, cmp_status, skd_in_flight(skdev),
                        cmp_bytes, skdev->proto_ver);

                if (cmp_cycle != skdev->skcomp_cycle) {
                        dev_dbg(&skdev->pdev->dev, "end of completions\n");
                        break;
                }
                /*
                 * Update the completion queue head index and possibly
                 * the completion cycle count. 8-bit wrap-around.
                 */
                skdev->skcomp_ix++;
                if (skdev->skcomp_ix >= SKD_N_COMPLETION_ENTRY) {
                        skdev->skcomp_ix = 0;
                        skdev->skcomp_cycle++;
                }

                /*
                 * The command context is a unique 32-bit ID. The low order
                 * bits help locate the request. The request is usually a
                 * r/w request (see skd_start() above) or a special request.
                 */
                req_id = cmp_cntxt;
                tag = req_id & SKD_ID_SLOT_AND_TABLE_MASK;

                /* Is this other than a r/w request? */
                if (tag >= skdev->num_req_context) {
                        /*
                         * This is not a completion for a r/w request.
                         */
                        WARN_ON_ONCE(blk_mq_tag_to_rq(skdev->tag_set.tags[hwq],
                                                      tag));
                        skd_complete_other(skdev, skcmp, skerr);
                        continue;
                }

                rq = blk_mq_tag_to_rq(skdev->tag_set.tags[hwq], tag);
                if (WARN(!rq, "No request for tag %#x -> %#x\n", cmp_cntxt,
                         tag))
                        continue;
                skreq = blk_mq_rq_to_pdu(rq);

                /*
                 * Make sure the request ID for the slot matches.
                 */
                if (skreq->id != req_id) {
                        dev_err(&skdev->pdev->dev,
                                "Completion mismatch comp_id=0x%04x skreq=0x%04x new=0x%04x\n",
                                req_id, skreq->id, cmp_cntxt);

                        continue;
                }

                SKD_ASSERT(skreq->state == SKD_REQ_STATE_BUSY);

                skreq->completion = *skcmp;
                if (unlikely(cmp_status == SAM_STAT_CHECK_CONDITION)) {
                        skreq->err_info = *skerr;
                        skd_log_check_status(skdev, cmp_status, skerr->key,
                                             skerr->code, skerr->qual,
                                             skerr->fruc);
                }
                /* Release DMA resources for the request. */
                if (skreq->n_sg > 0)
                        skd_postop_sg_list(skdev, skreq);

                skd_release_skreq(skdev, skreq);

                /*
                 * Capture the outcome and post it back to the native request.
                 */
                if (likely(cmp_status == SAM_STAT_GOOD)) {
                        skreq->status = BLK_STS_OK;
                        if (likely(!blk_should_fake_timeout(rq->q)))
                                blk_mq_complete_request(rq);
                } else {
                        skd_resolve_req_exception(skdev, skreq, rq);
                }

                /* skd_isr_comp_limit equal zero means no limit */
                if (limit) {
                        if (++processed >= limit) {
                                rc = 1;
                                break;
                        }
                }
        }

        if (skdev->state == SKD_DRVR_STATE_PAUSING &&
            skd_in_flight(skdev) == 0) {
                skdev->state = SKD_DRVR_STATE_PAUSED;
                wake_up_interruptible(&skdev->waitq);
        }

        return rc;
}

static void skd_complete_other(struct skd_device *skdev,
                               struct fit_completion_entry_v1 *skcomp,
                               struct fit_comp_error_info *skerr)
{
        u32 req_id = 0;
        u32 req_table;
        u32 req_slot;
        struct skd_special_context *skspcl;

        lockdep_assert_held(&skdev->lock);

        req_id = skcomp->tag;
        req_table = req_id & SKD_ID_TABLE_MASK;
        req_slot = req_id & SKD_ID_SLOT_MASK;

        dev_dbg(&skdev->pdev->dev, "table=0x%x id=0x%x slot=%d\n", req_table,
                req_id, req_slot);

        /*
         * Based on the request id, determine how to dispatch this completion.
         * This swich/case is finding the good cases and forwarding the
         * completion entry. Errors are reported below the switch.
         */
        switch (req_table) {
        case SKD_ID_RW_REQUEST:
                /*
                 * The caller, skd_isr_completion_posted() above,
                 * handles r/w requests. The only way we get here
                 * is if the req_slot is out of bounds.
                 */
                break;

        case SKD_ID_INTERNAL:
                if (req_slot == 0) {
                        skspcl = &skdev->internal_skspcl;
                        if (skspcl->req.id == req_id &&
                            skspcl->req.state == SKD_REQ_STATE_BUSY) {
                                skd_complete_internal(skdev,
                                                      skcomp, skerr, skspcl);
                                return;
                        }
                }
                break;

        case SKD_ID_FIT_MSG:
                /*
                 * These id's should never appear in a completion record.
                 */
                break;

        default:
                /*
                 * These id's should never appear anywhere;
                 */
                break;
        }

        /*
         * If we get here it is a bad or stale id.
         */
}

static void skd_reset_skcomp(struct skd_device *skdev)
{
        memset(skdev->skcomp_table, 0, SKD_SKCOMP_SIZE);

        skdev->skcomp_ix = 0;
        skdev->skcomp_cycle = 1;
}

/*
 *****************************************************************************
 * INTERRUPTS
 *****************************************************************************
 */
static void skd_completion_worker(struct work_struct *work)
{
        struct skd_device *skdev =
                container_of(work, struct skd_device, completion_worker);
        unsigned long flags;
        int flush_enqueued = 0;

        spin_lock_irqsave(&skdev->lock, flags);

        /*
         * pass in limit=0, which means no limit..
         * process everything in compq
         */
        skd_isr_completion_posted(skdev, 0, &flush_enqueued);
        schedule_work(&skdev->start_queue);

        spin_unlock_irqrestore(&skdev->lock, flags);
}

static void skd_isr_msg_from_dev(struct skd_device *skdev);

static irqreturn_t
skd_isr(int irq, void *ptr)
{
        struct skd_device *skdev = ptr;
        u32 intstat;
        u32 ack;
        int rc = 0;
        int deferred = 0;
        int flush_enqueued = 0;

        spin_lock(&skdev->lock);

        for (;; ) {
                intstat = SKD_READL(skdev, FIT_INT_STATUS_HOST);

                ack = FIT_INT_DEF_MASK;
                ack &= intstat;

                dev_dbg(&skdev->pdev->dev, "intstat=0x%x ack=0x%x\n", intstat,
                        ack);

                /* As long as there is an int pending on device, keep
                 * running loop.  When none, get out, but if we've never
                 * done any processing, call completion handler?
                 */
                if (ack == 0) {
                        /* No interrupts on device, but run the completion
                         * processor anyway?
                         */
                        if (rc == 0)
                                if (likely (skdev->state
                                        == SKD_DRVR_STATE_ONLINE))
                                        deferred = 1;
                        break;
                }

                rc = IRQ_HANDLED;

                SKD_WRITEL(skdev, ack, FIT_INT_STATUS_HOST);

                if (likely((skdev->state != SKD_DRVR_STATE_LOAD) &&
                           (skdev->state != SKD_DRVR_STATE_STOPPING))) {
                        if (intstat & FIT_ISH_COMPLETION_POSTED) {
                                /*
                                 * If we have already deferred completion
                                 * processing, don't bother running it again
                                 */
                                if (deferred == 0)
                                        deferred =
                                                skd_isr_completion_posted(skdev,
                                                skd_isr_comp_limit, &flush_enqueued);
                        }

                        if (intstat & FIT_ISH_FW_STATE_CHANGE) {
                                skd_isr_fwstate(skdev);
                                if (skdev->state == SKD_DRVR_STATE_FAULT ||
                                    skdev->state ==
                                    SKD_DRVR_STATE_DISAPPEARED) {
                                        spin_unlock(&skdev->lock);
                                        return rc;
                                }
                        }

                        if (intstat & FIT_ISH_MSG_FROM_DEV)
                                skd_isr_msg_from_dev(skdev);
                }
        }

        if (unlikely(flush_enqueued))
                schedule_work(&skdev->start_queue);

        if (deferred)
                schedule_work(&skdev->completion_worker);
        else if (!flush_enqueued)
                schedule_work(&skdev->start_queue);

        spin_unlock(&skdev->lock);

        return rc;
}

static void skd_drive_fault(struct skd_device *skdev)
{
        skdev->state = SKD_DRVR_STATE_FAULT;
        dev_err(&skdev->pdev->dev, "Drive FAULT\n");
}

static void skd_drive_disappeared(struct skd_device *skdev)
{
        skdev->state = SKD_DRVR_STATE_DISAPPEARED;
        dev_err(&skdev->pdev->dev, "Drive DISAPPEARED\n");
}

static void skd_isr_fwstate(struct skd_device *skdev)
{
        u32 sense;
        u32 state;
        u32 mtd;
        int prev_driver_state = skdev->state;

        sense = SKD_READL(skdev, FIT_STATUS);
        state = sense & FIT_SR_DRIVE_STATE_MASK;

        dev_err(&skdev->pdev->dev, "s1120 state %s(%d)=>%s(%d)\n",
                skd_drive_state_to_str(skdev->drive_state), skdev->drive_state,
                skd_drive_state_to_str(state), state);

        skdev->drive_state = state;

        switch (skdev->drive_state) {
        case FIT_SR_DRIVE_INIT:
                if (skdev->state == SKD_DRVR_STATE_PROTOCOL_MISMATCH) {
                        skd_disable_interrupts(skdev);
                        break;
                }
                if (skdev->state == SKD_DRVR_STATE_RESTARTING)
                        skd_recover_requests(skdev);
                if (skdev->state == SKD_DRVR_STATE_WAIT_BOOT) {
                        skdev->timer_countdown = SKD_STARTING_TIMO;
                        skdev->state = SKD_DRVR_STATE_STARTING;
                        skd_soft_reset(skdev);
                        break;
                }
                mtd = FIT_MXD_CONS(FIT_MTD_FITFW_INIT, 0, 0);
                SKD_WRITEL(skdev, mtd, FIT_MSG_TO_DEVICE);
                skdev->last_mtd = mtd;
                break;

        case FIT_SR_DRIVE_ONLINE:
                skdev->cur_max_queue_depth = skd_max_queue_depth;
                if (skdev->cur_max_queue_depth > skdev->dev_max_queue_depth)
                        skdev->cur_max_queue_depth = skdev->dev_max_queue_depth;

                skdev->queue_low_water_mark =
                        skdev->cur_max_queue_depth * 2 / 3 + 1;
                if (skdev->queue_low_water_mark < 1)
                        skdev->queue_low_water_mark = 1;
                dev_info(&skdev->pdev->dev,
                         "Queue depth limit=%d dev=%d lowat=%d\n",
                         skdev->cur_max_queue_depth,
                         skdev->dev_max_queue_depth,
                         skdev->queue_low_water_mark);

                skd_refresh_device_data(skdev);
                break;

        case FIT_SR_DRIVE_BUSY:
                skdev->state = SKD_DRVR_STATE_BUSY;
                skdev->timer_countdown = SKD_BUSY_TIMO;
                skd_quiesce_dev(skdev);
                break;
        case FIT_SR_DRIVE_BUSY_SANITIZE:
                /* set timer for 3 seconds, we'll abort any unfinished
                 * commands after that expires
                 */
                skdev->state = SKD_DRVR_STATE_BUSY_SANITIZE;
                skdev->timer_countdown = SKD_TIMER_SECONDS(3);
                schedule_work(&skdev->start_queue);
                break;
        case FIT_SR_DRIVE_BUSY_ERASE:
                skdev->state = SKD_DRVR_STATE_BUSY_ERASE;
                skdev->timer_countdown = SKD_BUSY_TIMO;
                break;
        case FIT_SR_DRIVE_OFFLINE:
                skdev->state = SKD_DRVR_STATE_IDLE;
                break;
        case FIT_SR_DRIVE_SOFT_RESET:
                switch (skdev->state) {
                case SKD_DRVR_STATE_STARTING:
                case SKD_DRVR_STATE_RESTARTING:
                        /* Expected by a caller of skd_soft_reset() */
                        break;
                default:
                        skdev->state = SKD_DRVR_STATE_RESTARTING;
                        break;
                }
                break;
        case FIT_SR_DRIVE_FW_BOOTING:
                dev_dbg(&skdev->pdev->dev, "ISR FIT_SR_DRIVE_FW_BOOTING\n");
                skdev->state = SKD_DRVR_STATE_WAIT_BOOT;
                skdev->timer_countdown = SKD_WAIT_BOOT_TIMO;
                break;

        case FIT_SR_DRIVE_DEGRADED:
        case FIT_SR_PCIE_LINK_DOWN:
        case FIT_SR_DRIVE_NEED_FW_DOWNLOAD:
                break;

        case FIT_SR_DRIVE_FAULT:
                skd_drive_fault(skdev);
                skd_recover_requests(skdev);
                schedule_work(&skdev->start_queue);
                break;

        /* PCIe bus returned all Fs? */
        case 0xFF:
                dev_info(&skdev->pdev->dev, "state=0x%x sense=0x%x\n", state,
                         sense);
                skd_drive_disappeared(skdev);
                skd_recover_requests(skdev);
                schedule_work(&skdev->start_queue);
                break;
        default:
                /*
                 * Uknown FW State. Wait for a state we recognize.
                 */
                break;
        }
        dev_err(&skdev->pdev->dev, "Driver state %s(%d)=>%s(%d)\n",
                skd_skdev_state_to_str(prev_driver_state), prev_driver_state,
                skd_skdev_state_to_str(skdev->state), skdev->state);
}

static bool skd_recover_request(struct request *req, void *data, bool reserved)
{
        struct skd_device *const skdev = data;
        struct skd_request_context *skreq = blk_mq_rq_to_pdu(req);

        if (skreq->state != SKD_REQ_STATE_BUSY)
                return true;

        skd_log_skreq(skdev, skreq, "recover");

        /* Release DMA resources for the request. */
        if (skreq->n_sg > 0)
                skd_postop_sg_list(skdev, skreq);

        skreq->state = SKD_REQ_STATE_IDLE;
        skreq->status = BLK_STS_IOERR;
        blk_mq_complete_request(req);
        return true;
}

static void skd_recover_requests(struct skd_device *skdev)
{
        blk_mq_tagset_busy_iter(&skdev->tag_set, skd_recover_request, skdev);
}

static void skd_isr_msg_from_dev(struct skd_device *skdev)
{
        u32 mfd;
        u32 mtd;
        u32 data;

        mfd = SKD_READL(skdev, FIT_MSG_FROM_DEVICE);

        dev_dbg(&skdev->pdev->dev, "mfd=0x%x last_mtd=0x%x\n", mfd,
                skdev->last_mtd);

        /* ignore any mtd that is an ack for something we didn't send */
        if (FIT_MXD_TYPE(mfd) != FIT_MXD_TYPE(skdev->last_mtd))
                return;

        switch (FIT_MXD_TYPE(mfd)) {
        case FIT_MTD_FITFW_INIT:
                skdev->proto_ver = FIT_PROTOCOL_MAJOR_VER(mfd);

                if (skdev->proto_ver != FIT_PROTOCOL_VERSION_1) {
                        dev_err(&skdev->pdev->dev, "protocol mismatch\n");
                        dev_err(&skdev->pdev->dev, "  got=%d support=%d\n",
                                skdev->proto_ver, FIT_PROTOCOL_VERSION_1);
                        dev_err(&skdev->pdev->dev, "  please upgrade driver\n");
                        skdev->state = SKD_DRVR_STATE_PROTOCOL_MISMATCH;
                        skd_soft_reset(skdev);
                        break;
                }
                mtd = FIT_MXD_CONS(FIT_MTD_GET_CMDQ_DEPTH, 0, 0);
                SKD_WRITEL(skdev, mtd, FIT_MSG_TO_DEVICE);
                skdev->last_mtd = mtd;
                break;

        case FIT_MTD_GET_CMDQ_DEPTH:
                skdev->dev_max_queue_depth = FIT_MXD_DATA(mfd);
                mtd = FIT_MXD_CONS(FIT_MTD_SET_COMPQ_DEPTH, 0,
                                   SKD_N_COMPLETION_ENTRY);
                SKD_WRITEL(skdev, mtd, FIT_MSG_TO_DEVICE);
                skdev->last_mtd = mtd;
                break;

        case FIT_MTD_SET_COMPQ_DEPTH:
                SKD_WRITEQ(skdev, skdev->cq_dma_address, FIT_MSG_TO_DEVICE_ARG);
                mtd = FIT_MXD_CONS(FIT_MTD_SET_COMPQ_ADDR, 0, 0);
                SKD_WRITEL(skdev, mtd, FIT_MSG_TO_DEVICE);
                skdev->last_mtd = mtd;
                break;

        case FIT_MTD_SET_COMPQ_ADDR:
                skd_reset_skcomp(skdev);
                mtd = FIT_MXD_CONS(FIT_MTD_CMD_LOG_HOST_ID, 0, skdev->devno);
                SKD_WRITEL(skdev, mtd, FIT_MSG_TO_DEVICE);
                skdev->last_mtd = mtd;
                break;

        case FIT_MTD_CMD_LOG_HOST_ID:
                /* hardware interface overflows in y2106 */
                skdev->connect_time_stamp = (u32)ktime_get_real_seconds();
                data = skdev->connect_time_stamp & 0xFFFF;
                mtd = FIT_MXD_CONS(FIT_MTD_CMD_LOG_TIME_STAMP_LO, 0, data);
                SKD_WRITEL(skdev, mtd, FIT_MSG_TO_DEVICE);
                skdev->last_mtd = mtd;
                break;

        case FIT_MTD_CMD_LOG_TIME_STAMP_LO:
                skdev->drive_jiffies = FIT_MXD_DATA(mfd);
                data = (skdev->connect_time_stamp >> 16) & 0xFFFF;
                mtd = FIT_MXD_CONS(FIT_MTD_CMD_LOG_TIME_STAMP_HI, 0, data);
                SKD_WRITEL(skdev, mtd, FIT_MSG_TO_DEVICE);
                skdev->last_mtd = mtd;
                break;

        case FIT_MTD_CMD_LOG_TIME_STAMP_HI:
                skdev->drive_jiffies |= (FIT_MXD_DATA(mfd) << 16);
                mtd = FIT_MXD_CONS(FIT_MTD_ARM_QUEUE, 0, 0);
                SKD_WRITEL(skdev, mtd, FIT_MSG_TO_DEVICE);
                skdev->last_mtd = mtd;

                dev_err(&skdev->pdev->dev, "Time sync driver=0x%x device=0x%x\n",

                        skdev->connect_time_stamp, skdev->drive_jiffies);
                break;

        case FIT_MTD_ARM_QUEUE:
                skdev->last_mtd = 0;
                /*
                 * State should be, or soon will be, FIT_SR_DRIVE_ONLINE.
                 */
                break;

        default:
                break;
        }
}

static void skd_disable_interrupts(struct skd_device *skdev)
{
        u32 sense;

        sense = SKD_READL(skdev, FIT_CONTROL);
        sense &= ~FIT_CR_ENABLE_INTERRUPTS;
        SKD_WRITEL(skdev, sense, FIT_CONTROL);
        dev_dbg(&skdev->pdev->dev, "sense 0x%x\n", sense);

        /* Note that the 1s is written. A 1-bit means
         * disable, a 0 means enable.
         */
        SKD_WRITEL(skdev, ~0, FIT_INT_MASK_HOST);
}

static void skd_enable_interrupts(struct skd_device *skdev)
{
        u32 val;

        /* unmask interrupts first */
        val = FIT_ISH_FW_STATE_CHANGE +
              FIT_ISH_COMPLETION_POSTED + FIT_ISH_MSG_FROM_DEV;

        /* Note that the compliment of mask is written. A 1-bit means
         * disable, a 0 means enable. */
        SKD_WRITEL(skdev, ~val, FIT_INT_MASK_HOST);
        dev_dbg(&skdev->pdev->dev, "interrupt mask=0x%x\n", ~val);

        val = SKD_READL(skdev, FIT_CONTROL);
        val |= FIT_CR_ENABLE_INTERRUPTS;
        dev_dbg(&skdev->pdev->dev, "control=0x%x\n", val);
        SKD_WRITEL(skdev, val, FIT_CONTROL);
}

/*
 *****************************************************************************
 * START, STOP, RESTART, QUIESCE, UNQUIESCE
 *****************************************************************************
 */

static void skd_soft_reset(struct skd_device *skdev)
{
        u32 val;

        val = SKD_READL(skdev, FIT_CONTROL);
        val |= (FIT_CR_SOFT_RESET);
        dev_dbg(&skdev->pdev->dev, "control=0x%x\n", val);
        SKD_WRITEL(skdev, val, FIT_CONTROL);
}

static void skd_start_device(struct skd_device *skdev)
{
        unsigned long flags;
        u32 sense;
        u32 state;

        spin_lock_irqsave(&skdev->lock, flags);

        /* ack all ghost interrupts */
        SKD_WRITEL(skdev, FIT_INT_DEF_MASK, FIT_INT_STATUS_HOST);

        sense = SKD_READL(skdev, FIT_STATUS);

        dev_dbg(&skdev->pdev->dev, "initial status=0x%x\n", sense);

        state = sense & FIT_SR_DRIVE_STATE_MASK;
        skdev->drive_state = state;
        skdev->last_mtd = 0;

        skdev->state = SKD_DRVR_STATE_STARTING;
        skdev->timer_countdown = SKD_STARTING_TIMO;

        skd_enable_interrupts(skdev);

        switch (skdev->drive_state) {
        case FIT_SR_DRIVE_OFFLINE:
                dev_err(&skdev->pdev->dev, "Drive offline...\n");
                break;

        case FIT_SR_DRIVE_FW_BOOTING:
                dev_dbg(&skdev->pdev->dev, "FIT_SR_DRIVE_FW_BOOTING\n");
                skdev->state = SKD_DRVR_STATE_WAIT_BOOT;
                skdev->timer_countdown = SKD_WAIT_BOOT_TIMO;
                break;

        case FIT_SR_DRIVE_BUSY_SANITIZE:
                dev_info(&skdev->pdev->dev, "Start: BUSY_SANITIZE\n");
                skdev->state = SKD_DRVR_STATE_BUSY_SANITIZE;
                skdev->timer_countdown = SKD_STARTED_BUSY_TIMO;
                break;

        case FIT_SR_DRIVE_BUSY_ERASE:
                dev_info(&skdev->pdev->dev, "Start: BUSY_ERASE\n");
                skdev->state = SKD_DRVR_STATE_BUSY_ERASE;
                skdev->timer_countdown = SKD_STARTED_BUSY_TIMO;
                break;

        case FIT_SR_DRIVE_INIT:
        case FIT_SR_DRIVE_ONLINE:
                skd_soft_reset(skdev);
                break;

        case FIT_SR_DRIVE_BUSY:
                dev_err(&skdev->pdev->dev, "Drive Busy...\n");
                skdev->state = SKD_DRVR_STATE_BUSY;
                skdev->timer_countdown = SKD_STARTED_BUSY_TIMO;
                break;

        case FIT_SR_DRIVE_SOFT_RESET:
                dev_err(&skdev->pdev->dev, "drive soft reset in prog\n");
                break;

        case FIT_SR_DRIVE_FAULT:
                /* Fault state is bad...soft reset won't do it...
                 * Hard reset, maybe, but does it work on device?
                 * For now, just fault so the system doesn't hang.
                 */
                skd_drive_fault(skdev);
                /*start the queue so we can respond with error to requests */
                dev_dbg(&skdev->pdev->dev, "starting queue\n");
                schedule_work(&skdev->start_queue);
                skdev->gendisk_on = -1;
                wake_up_interruptible(&skdev->waitq);
                break;

        case 0xFF:
                /* Most likely the device isn't there or isn't responding
                 * to the BAR1 addresses. */
                skd_drive_disappeared(skdev);
                /*start the queue so we can respond with error to requests */
                dev_dbg(&skdev->pdev->dev,
                        "starting queue to error-out reqs\n");
                schedule_work(&skdev->start_queue);
                skdev->gendisk_on = -1;
                wake_up_interruptible(&skdev->waitq);
                break;

        default:
                dev_err(&skdev->pdev->dev, "Start: unknown state %x\n",
                        skdev->drive_state);
                break;
        }

        state = SKD_READL(skdev, FIT_CONTROL);
        dev_dbg(&skdev->pdev->dev, "FIT Control Status=0x%x\n", state);

        state = SKD_READL(skdev, FIT_INT_STATUS_HOST);
        dev_dbg(&skdev->pdev->dev, "Intr Status=0x%x\n", state);

        state = SKD_READL(skdev, FIT_INT_MASK_HOST);
        dev_dbg(&skdev->pdev->dev, "Intr Mask=0x%x\n", state);

        state = SKD_READL(skdev, FIT_MSG_FROM_DEVICE);
        dev_dbg(&skdev->pdev->dev, "Msg from Dev=0x%x\n", state);

        state = SKD_READL(skdev, FIT_HW_VERSION);
        dev_dbg(&skdev->pdev->dev, "HW version=0x%x\n", state);

        spin_unlock_irqrestore(&skdev->lock, flags);
}

static void skd_stop_device(struct skd_device *skdev)
{
        unsigned long flags;
        struct skd_special_context *skspcl = &skdev->internal_skspcl;
        u32 dev_state;
        int i;

        spin_lock_irqsave(&skdev->lock, flags);

        if (skdev->state != SKD_DRVR_STATE_ONLINE) {
                dev_err(&skdev->pdev->dev, "%s not online no sync\n", __func__);
                goto stop_out;
        }

        if (skspcl->req.state != SKD_REQ_STATE_IDLE) {
                dev_err(&skdev->pdev->dev, "%s no special\n", __func__);
                goto stop_out;
        }

        skdev->state = SKD_DRVR_STATE_SYNCING;
        skdev->sync_done = 0;

        skd_send_internal_skspcl(skdev, skspcl, SYNCHRONIZE_CACHE);

        spin_unlock_irqrestore(&skdev->lock, flags);

        wait_event_interruptible_timeout(skdev->waitq,
                                         (skdev->sync_done), (10 * HZ));

        spin_lock_irqsave(&skdev->lock, flags);

        switch (skdev->sync_done) {
        case 0:
                dev_err(&skdev->pdev->dev, "%s no sync\n", __func__);
                break;
        case 1:
                dev_err(&skdev->pdev->dev, "%s sync done\n", __func__);
                break;
        default:
                dev_err(&skdev->pdev->dev, "%s sync error\n", __func__);
        }

stop_out:
        skdev->state = SKD_DRVR_STATE_STOPPING;
        spin_unlock_irqrestore(&skdev->lock, flags);

        skd_kill_timer(skdev);

        spin_lock_irqsave(&skdev->lock, flags);
        skd_disable_interrupts(skdev);

        /* ensure all ints on device are cleared */
        /* soft reset the device to unload with a clean slate */
        SKD_WRITEL(skdev, FIT_INT_DEF_MASK, FIT_INT_STATUS_HOST);
        SKD_WRITEL(skdev, FIT_CR_SOFT_RESET, FIT_CONTROL);

        spin_unlock_irqrestore(&skdev->lock, flags);

        /* poll every 100ms, 1 second timeout */
        for (i = 0; i < 10; i++) {
                dev_state =
                        SKD_READL(skdev, FIT_STATUS) & FIT_SR_DRIVE_STATE_MASK;
                if (dev_state == FIT_SR_DRIVE_INIT)
                        break;
                set_current_state(TASK_INTERRUPTIBLE);
                schedule_timeout(msecs_to_jiffies(100));
        }

        if (dev_state != FIT_SR_DRIVE_INIT)
                dev_err(&skdev->pdev->dev, "%s state error 0x%02x\n", __func__,
                        dev_state);
}

/* assume spinlock is held */
static void skd_restart_device(struct skd_device *skdev)
{
        u32 state;

        /* ack all ghost interrupts */
        SKD_WRITEL(skdev, FIT_INT_DEF_MASK, FIT_INT_STATUS_HOST);

        state = SKD_READL(skdev, FIT_STATUS);

        dev_dbg(&skdev->pdev->dev, "drive status=0x%x\n", state);

        state &= FIT_SR_DRIVE_STATE_MASK;
        skdev->drive_state = state;
        skdev->last_mtd = 0;

        skdev->state = SKD_DRVR_STATE_RESTARTING;
        skdev->timer_countdown = SKD_RESTARTING_TIMO;

        skd_soft_reset(skdev);
}

/* assume spinlock is held */
static int skd_quiesce_dev(struct skd_device *skdev)
{
        int rc = 0;

        switch (skdev->state) {
        case SKD_DRVR_STATE_BUSY:
        case SKD_DRVR_STATE_BUSY_IMMINENT:
                dev_dbg(&skdev->pdev->dev, "stopping queue\n");
                blk_mq_stop_hw_queues(skdev->queue);
                break;
        case SKD_DRVR_STATE_ONLINE:
        case SKD_DRVR_STATE_STOPPING:
        case SKD_DRVR_STATE_SYNCING:
        case SKD_DRVR_STATE_PAUSING:
        case SKD_DRVR_STATE_PAUSED:
        case SKD_DRVR_STATE_STARTING:
        case SKD_DRVR_STATE_RESTARTING:
        case SKD_DRVR_STATE_RESUMING:
        default:
                rc = -EINVAL;
                dev_dbg(&skdev->pdev->dev, "state [%d] not implemented\n",
                        skdev->state);
        }
        return rc;
}

/* assume spinlock is held */
static int skd_unquiesce_dev(struct skd_device *skdev)
{
        int prev_driver_state = skdev->state;

        skd_log_skdev(skdev, "unquiesce");
        if (skdev->state == SKD_DRVR_STATE_ONLINE) {
                dev_dbg(&skdev->pdev->dev, "**** device already ONLINE\n");
                return 0;
        }
        if (skdev->drive_state != FIT_SR_DRIVE_ONLINE) {
                /*
                 * If there has been an state change to other than
                 * ONLINE, we will rely on controller state change
                 * to come back online and restart the queue.
                 * The BUSY state means that driver is ready to
                 * continue normal processing but waiting for controller
                 * to become available.
                 */
                skdev->state = SKD_DRVR_STATE_BUSY;
                dev_dbg(&skdev->pdev->dev, "drive BUSY state\n");
                return 0;
        }

        /*
         * Drive has just come online, driver is either in startup,
         * paused performing a task, or bust waiting for hardware.
         */
        switch (skdev->state) {
        case SKD_DRVR_STATE_PAUSED:
        case SKD_DRVR_STATE_BUSY:
        case SKD_DRVR_STATE_BUSY_IMMINENT:
        case SKD_DRVR_STATE_BUSY_ERASE:
        case SKD_DRVR_STATE_STARTING:
        case SKD_DRVR_STATE_RESTARTING:
        case SKD_DRVR_STATE_FAULT:
        case SKD_DRVR_STATE_IDLE:
        case SKD_DRVR_STATE_LOAD:
                skdev->state = SKD_DRVR_STATE_ONLINE;
                dev_err(&skdev->pdev->dev, "Driver state %s(%d)=>%s(%d)\n",
                        skd_skdev_state_to_str(prev_driver_state),
                        prev_driver_state, skd_skdev_state_to_str(skdev->state),
                        skdev->state);
                dev_dbg(&skdev->pdev->dev,
                        "**** device ONLINE...starting block queue\n");
                dev_dbg(&skdev->pdev->dev, "starting queue\n");
                dev_info(&skdev->pdev->dev, "STEC s1120 ONLINE\n");
                schedule_work(&skdev->start_queue);
                skdev->gendisk_on = 1;
                wake_up_interruptible(&skdev->waitq);
                break;

        case SKD_DRVR_STATE_DISAPPEARED:
        default:
                dev_dbg(&skdev->pdev->dev,
                        "**** driver state %d, not implemented\n",
                        skdev->state);
                return -EBUSY;
        }
        return 0;
}

/*
 *****************************************************************************
 * PCIe MSI/MSI-X INTERRUPT HANDLERS
 *****************************************************************************
 */

static irqreturn_t skd_reserved_isr(int irq, void *skd_host_data)
{
        struct skd_device *skdev = skd_host_data;
        unsigned long flags;

        spin_lock_irqsave(&skdev->lock, flags);
        dev_dbg(&skdev->pdev->dev, "MSIX = 0x%x\n",
                SKD_READL(skdev, FIT_INT_STATUS_HOST));
        dev_err(&skdev->pdev->dev, "MSIX reserved irq %d = 0x%x\n", irq,
                SKD_READL(skdev, FIT_INT_STATUS_HOST));
        SKD_WRITEL(skdev, FIT_INT_RESERVED_MASK, FIT_INT_STATUS_HOST);
        spin_unlock_irqrestore(&skdev->lock, flags);
        return IRQ_HANDLED;
}

static irqreturn_t skd_statec_isr(int irq, void *skd_host_data)
{
        struct skd_device *skdev = skd_host_data;
        unsigned long flags;

        spin_lock_irqsave(&skdev->lock, flags);
        dev_dbg(&skdev->pdev->dev, "MSIX = 0x%x\n",
                SKD_READL(skdev, FIT_INT_STATUS_HOST));
        SKD_WRITEL(skdev, FIT_ISH_FW_STATE_CHANGE, FIT_INT_STATUS_HOST);
        skd_isr_fwstate(skdev);
        spin_unlock_irqrestore(&skdev->lock, flags);
        return IRQ_HANDLED;
}

static irqreturn_t skd_comp_q(int irq, void *skd_host_data)
{
        struct skd_device *skdev = skd_host_data;
        unsigned long flags;
        int flush_enqueued = 0;
        int deferred;

        spin_lock_irqsave(&skdev->lock, flags);
        dev_dbg(&skdev->pdev->dev, "MSIX = 0x%x\n",
                SKD_READL(skdev, FIT_INT_STATUS_HOST));
        SKD_WRITEL(skdev, FIT_ISH_COMPLETION_POSTED, FIT_INT_STATUS_HOST);
        deferred = skd_isr_completion_posted(skdev, skd_isr_comp_limit,
                                                &flush_enqueued);
        if (flush_enqueued)
                schedule_work(&skdev->start_queue);

        if (deferred)
                schedule_work(&skdev->completion_worker);
        else if (!flush_enqueued)
                schedule_work(&skdev->start_queue);

        spin_unlock_irqrestore(&skdev->lock, flags);

        return IRQ_HANDLED;
}

static irqreturn_t skd_msg_isr(int irq, void *skd_host_data)
{
        struct skd_device *skdev = skd_host_data;
        unsigned long flags;

        spin_lock_irqsave(&skdev->lock, flags);
        dev_dbg(&skdev->pdev->dev, "MSIX = 0x%x\n",
                SKD_READL(skdev, FIT_INT_STATUS_HOST));
        SKD_WRITEL(skdev, FIT_ISH_MSG_FROM_DEV, FIT_INT_STATUS_HOST);
        skd_isr_msg_from_dev(skdev);
        spin_unlock_irqrestore(&skdev->lock, flags);
        return IRQ_HANDLED;
}

static irqreturn_t skd_qfull_isr(int irq, void *skd_host_data)
{
        struct skd_device *skdev = skd_host_data;
        unsigned long flags;

        spin_lock_irqsave(&skdev->lock, flags);
        dev_dbg(&skdev->pdev->dev, "MSIX = 0x%x\n",
                SKD_READL(skdev, FIT_INT_STATUS_HOST));
        SKD_WRITEL(skdev, FIT_INT_QUEUE_FULL, FIT_INT_STATUS_HOST);
        spin_unlock_irqrestore(&skdev->lock, flags);
        return IRQ_HANDLED;
}

/*
 *****************************************************************************
 * PCIe MSI/MSI-X SETUP
 *****************************************************************************
 */

struct skd_msix_entry {
        char isr_name[30];
};

struct skd_init_msix_entry {
        const char *name;
        irq_handler_t handler;
};

#define SKD_MAX_MSIX_COUNT              13
#define SKD_MIN_MSIX_COUNT              7
#define SKD_BASE_MSIX_IRQ               4

static struct skd_init_msix_entry msix_entries[SKD_MAX_MSIX_COUNT] = {
        { "(DMA 0)",        skd_reserved_isr },
        { "(DMA 1)",        skd_reserved_isr },
        { "(DMA 2)",        skd_reserved_isr },
        { "(DMA 3)",        skd_reserved_isr },
        { "(State Change)", skd_statec_isr   },
        { "(COMPL_Q)",      skd_comp_q       },
        { "(MSG)",          skd_msg_isr      },
        { "(Reserved)",     skd_reserved_isr },
        { "(Reserved)",     skd_reserved_isr },
        { "(Queue Full 0)", skd_qfull_isr    },
        { "(Queue Full 1)", skd_qfull_isr    },
        { "(Queue Full 2)", skd_qfull_isr    },
        { "(Queue Full 3)", skd_qfull_isr    },
};

static int skd_acquire_msix(struct skd_device *skdev)
{
        int i, rc;
        struct pci_dev *pdev = skdev->pdev;

        rc = pci_alloc_irq_vectors(pdev, SKD_MAX_MSIX_COUNT, SKD_MAX_MSIX_COUNT,
                        PCI_IRQ_MSIX);
        if (rc < 0) {
                dev_err(&skdev->pdev->dev, "failed to enable MSI-X %d\n", rc);
                goto out;
        }

        skdev->msix_entries = kcalloc(SKD_MAX_MSIX_COUNT,
                        sizeof(struct skd_msix_entry), GFP_KERNEL);
        if (!skdev->msix_entries) {
                rc = -ENOMEM;
                dev_err(&skdev->pdev->dev, "msix table allocation error\n");
                goto out;
        }

        /* Enable MSI-X vectors for the base queue */
        for (i = 0; i < SKD_MAX_MSIX_COUNT; i++) {
                struct skd_msix_entry *qentry = &skdev->msix_entries[i];

                snprintf(qentry->isr_name, sizeof(qentry->isr_name),
                         "%s%d-msix %s", DRV_NAME, skdev->devno,
                         msix_entries[i].name);

                rc = devm_request_irq(&skdev->pdev->dev,
                                pci_irq_vector(skdev->pdev, i),
                                msix_entries[i].handler, 0,
                                qentry->isr_name, skdev);
                if (rc) {
                        dev_err(&skdev->pdev->dev,
                                "Unable to register(%d) MSI-X handler %d: %s\n",
                                rc, i, qentry->isr_name);
                        goto msix_out;
                }
        }

        dev_dbg(&skdev->pdev->dev, "%d msix irq(s) enabled\n",
                SKD_MAX_MSIX_COUNT);
        return 0;

msix_out:
        while (--i >= 0)
                devm_free_irq(&pdev->dev, pci_irq_vector(pdev, i), skdev);
out:
        kfree(skdev->msix_entries);
        skdev->msix_entries = NULL;
        return rc;
}

static int skd_acquire_irq(struct skd_device *skdev)
{
        struct pci_dev *pdev = skdev->pdev;
        unsigned int irq_flag = PCI_IRQ_LEGACY;
        int rc;

        if (skd_isr_type == SKD_IRQ_MSIX) {
                rc = skd_acquire_msix(skdev);
                if (!rc)
                        return 0;

                dev_err(&skdev->pdev->dev,
                        "failed to enable MSI-X, re-trying with MSI %d\n", rc);
        }

        snprintf(skdev->isr_name, sizeof(skdev->isr_name), "%s%d", DRV_NAME,
                        skdev->devno);

        if (skd_isr_type != SKD_IRQ_LEGACY)
                irq_flag |= PCI_IRQ_MSI;
        rc = pci_alloc_irq_vectors(pdev, 1, 1, irq_flag);
        if (rc < 0) {
                dev_err(&skdev->pdev->dev,
                        "failed to allocate the MSI interrupt %d\n", rc);
                return rc;
        }

        rc = devm_request_irq(&pdev->dev, pdev->irq, skd_isr,
                        pdev->msi_enabled ? 0 : IRQF_SHARED,
                        skdev->isr_name, skdev);
        if (rc) {
                pci_free_irq_vectors(pdev);
                dev_err(&skdev->pdev->dev, "failed to allocate interrupt %d\n",
                        rc);
                return rc;
        }

        return 0;
}

static void skd_release_irq(struct skd_device *skdev)
{
        struct pci_dev *pdev = skdev->pdev;

        if (skdev->msix_entries) {
                int i;

                for (i = 0; i < SKD_MAX_MSIX_COUNT; i++) {
                        devm_free_irq(&pdev->dev, pci_irq_vector(pdev, i),
                                        skdev);
                }

                kfree(skdev->msix_entries);
                skdev->msix_entries = NULL;
        } else {
                devm_free_irq(&pdev->dev, pdev->irq, skdev);
        }

        pci_free_irq_vectors(pdev);
}

/*
 *****************************************************************************
 * CONSTRUCT
 *****************************************************************************
 */

static void *skd_alloc_dma(struct skd_device *skdev, struct kmem_cache *s,
                           dma_addr_t *dma_handle, gfp_t gfp,
                           enum dma_data_direction dir)
{
        struct device *dev = &skdev->pdev->dev;
        void *buf;

        buf = kmem_cache_alloc(s, gfp);
        if (!buf)
                return NULL;
        *dma_handle = dma_map_single(dev, buf,
                                     kmem_cache_size(s), dir);
        if (dma_mapping_error(dev, *dma_handle)) {
                kmem_cache_free(s, buf);
                buf = NULL;
        }
        return buf;
}

static void skd_free_dma(struct skd_device *skdev, struct kmem_cache *s,
                         void *vaddr, dma_addr_t dma_handle,
                         enum dma_data_direction dir)
{
        if (!vaddr)
                return;

        dma_unmap_single(&skdev->pdev->dev, dma_handle,
                         kmem_cache_size(s), dir);
        kmem_cache_free(s, vaddr);
}

static int skd_cons_skcomp(struct skd_device *skdev)
{
        int rc = 0;
        struct fit_completion_entry_v1 *skcomp;

        dev_dbg(&skdev->pdev->dev,
                "comp pci_alloc, total bytes %zd entries %d\n",
                SKD_SKCOMP_SIZE, SKD_N_COMPLETION_ENTRY);

        skcomp = dma_alloc_coherent(&skdev->pdev->dev, SKD_SKCOMP_SIZE,
                                    &skdev->cq_dma_address, GFP_KERNEL);

        if (skcomp == NULL) {
                rc = -ENOMEM;
                goto err_out;
        }

        skdev->skcomp_table = skcomp;
        skdev->skerr_table = (struct fit_comp_error_info *)((char *)skcomp +
                                                           sizeof(*skcomp) *
                                                           SKD_N_COMPLETION_ENTRY);

err_out:
        return rc;
}

static int skd_cons_skmsg(struct skd_device *skdev)
{
        int rc = 0;
        u32 i;

        dev_dbg(&skdev->pdev->dev,
                "skmsg_table kcalloc, struct %lu, count %u total %lu\n",
                sizeof(struct skd_fitmsg_context), skdev->num_fitmsg_context,
                sizeof(struct skd_fitmsg_context) * skdev->num_fitmsg_context);

        skdev->skmsg_table = kcalloc(skdev->num_fitmsg_context,
                                     sizeof(struct skd_fitmsg_context),
                                     GFP_KERNEL);
        if (skdev->skmsg_table == NULL) {
                rc = -ENOMEM;
                goto err_out;
        }

        for (i = 0; i < skdev->num_fitmsg_context; i++) {
                struct skd_fitmsg_context *skmsg;

                skmsg = &skdev->skmsg_table[i];

                skmsg->id = i + SKD_ID_FIT_MSG;

                skmsg->msg_buf = dma_alloc_coherent(&skdev->pdev->dev,
                                                    SKD_N_FITMSG_BYTES,
                                                    &skmsg->mb_dma_address,
                                                    GFP_KERNEL);
                if (skmsg->msg_buf == NULL) {
                        rc = -ENOMEM;
                        goto err_out;
                }

                WARN(((uintptr_t)skmsg->msg_buf | skmsg->mb_dma_address) &
                     (FIT_QCMD_ALIGN - 1),
                     "not aligned: msg_buf %p mb_dma_address %pad\n",
                     skmsg->msg_buf, &skmsg->mb_dma_address);
        }

err_out:
        return rc;
}

static struct fit_sg_descriptor *skd_cons_sg_list(struct skd_device *skdev,
                                                  u32 n_sg,
                                                  dma_addr_t *ret_dma_addr)
{
        struct fit_sg_descriptor *sg_list;

        sg_list = skd_alloc_dma(skdev, skdev->sglist_cache, ret_dma_addr,
                                GFP_DMA | __GFP_ZERO, DMA_TO_DEVICE);

        if (sg_list != NULL) {
                uint64_t dma_address = *ret_dma_addr;
                u32 i;

                for (i = 0; i < n_sg - 1; i++) {
                        uint64_t ndp_off;
                        ndp_off = (i + 1) * sizeof(struct fit_sg_descriptor);

                        sg_list[i].next_desc_ptr = dma_address + ndp_off;
                }
                sg_list[i].next_desc_ptr = 0LL;
        }

        return sg_list;
}

static void skd_free_sg_list(struct skd_device *skdev,
                             struct fit_sg_descriptor *sg_list,
                             dma_addr_t dma_addr)
{
        if (WARN_ON_ONCE(!sg_list))
                return;

        skd_free_dma(skdev, skdev->sglist_cache, sg_list, dma_addr,
                     DMA_TO_DEVICE);
}

static int skd_init_request(struct blk_mq_tag_set *set, struct request *rq,
                            unsigned int hctx_idx, unsigned int numa_node)
{
        struct skd_device *skdev = set->driver_data;
        struct skd_request_context *skreq = blk_mq_rq_to_pdu(rq);

        skreq->state = SKD_REQ_STATE_IDLE;
        skreq->sg = (void *)(skreq + 1);
        sg_init_table(skreq->sg, skd_sgs_per_request);
        skreq->sksg_list = skd_cons_sg_list(skdev, skd_sgs_per_request,
                                            &skreq->sksg_dma_address);

        return skreq->sksg_list ? 0 : -ENOMEM;
}

static void skd_exit_request(struct blk_mq_tag_set *set, struct request *rq,
                             unsigned int hctx_idx)
{
        struct skd_device *skdev = set->driver_data;
        struct skd_request_context *skreq = blk_mq_rq_to_pdu(rq);

        skd_free_sg_list(skdev, skreq->sksg_list, skreq->sksg_dma_address);
}

static int skd_cons_sksb(struct skd_device *skdev)
{
        int rc = 0;
        struct skd_special_context *skspcl;

        skspcl = &skdev->internal_skspcl;

        skspcl->req.id = 0 + SKD_ID_INTERNAL;
        skspcl->req.state = SKD_REQ_STATE_IDLE;

        skspcl->data_buf = skd_alloc_dma(skdev, skdev->databuf_cache,
                                         &skspcl->db_dma_address,
                                         GFP_DMA | __GFP_ZERO,
                                         DMA_BIDIRECTIONAL);
        if (skspcl->data_buf == NULL) {
                rc = -ENOMEM;
                goto err_out;
        }

        skspcl->msg_buf = skd_alloc_dma(skdev, skdev->msgbuf_cache,
                                        &skspcl->mb_dma_address,
                                        GFP_DMA | __GFP_ZERO, DMA_TO_DEVICE);
        if (skspcl->msg_buf == NULL) {
                rc = -ENOMEM;
                goto err_out;
        }

        skspcl->req.sksg_list = skd_cons_sg_list(skdev, 1,
                                                 &skspcl->req.sksg_dma_address);
        if (skspcl->req.sksg_list == NULL) {
                rc = -ENOMEM;
                goto err_out;
        }

        if (!skd_format_internal_skspcl(skdev)) {
                rc = -EINVAL;
                goto err_out;
        }

err_out:
        return rc;
}

static const struct blk_mq_ops skd_mq_ops = {
        .queue_rq       = skd_mq_queue_rq,
        .complete       = skd_complete_rq,
        .timeout        = skd_timed_out,
        .init_request   = skd_init_request,
        .exit_request   = skd_exit_request,
};

static int skd_cons_disk(struct skd_device *skdev)
{
        int rc = 0;
        struct gendisk *disk;
        struct request_queue *q;
        unsigned long flags;

        disk = alloc_disk(SKD_MINORS_PER_DEVICE);
        if (!disk) {
                rc = -ENOMEM;
                goto err_out;
        }

        skdev->disk = disk;
        sprintf(disk->disk_name, DRV_NAME "%u", skdev->devno);

        disk->major = skdev->major;
        disk->first_minor = skdev->devno * SKD_MINORS_PER_DEVICE;
        disk->fops = &skd_blockdev_ops;
        disk->private_data = skdev;

        memset(&skdev->tag_set, 0, sizeof(skdev->tag_set));
        skdev->tag_set.ops = &skd_mq_ops;
        skdev->tag_set.nr_hw_queues = 1;
        skdev->tag_set.queue_depth = skd_max_queue_depth;
        skdev->tag_set.cmd_size = sizeof(struct skd_request_context) +
                skdev->sgs_per_request * sizeof(struct scatterlist);
        skdev->tag_set.numa_node = NUMA_NO_NODE;
        skdev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE |
                BLK_ALLOC_POLICY_TO_MQ_FLAG(BLK_TAG_ALLOC_FIFO);
        skdev->tag_set.driver_data = skdev;
        rc = blk_mq_alloc_tag_set(&skdev->tag_set);
        if (rc)
                goto err_out;
        q = blk_mq_init_queue(&skdev->tag_set);
        if (IS_ERR(q)) {
                blk_mq_free_tag_set(&skdev->tag_set);
                rc = PTR_ERR(q);
                goto err_out;
        }
        q->queuedata = skdev;

        skdev->queue = q;
        disk->queue = q;

        blk_queue_write_cache(q, true, true);
        blk_queue_max_segments(q, skdev->sgs_per_request);
        blk_queue_max_hw_sectors(q, SKD_N_MAX_SECTORS);

        /* set optimal I/O size to 8KB */
        blk_queue_io_opt(q, 8192);

        blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
        blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, q);

        blk_queue_rq_timeout(q, 8 * HZ);

        spin_lock_irqsave(&skdev->lock, flags);
        dev_dbg(&skdev->pdev->dev, "stopping queue\n");
        blk_mq_stop_hw_queues(skdev->queue);
        spin_unlock_irqrestore(&skdev->lock, flags);

err_out:
        return rc;
}

#define SKD_N_DEV_TABLE         16u
static u32 skd_next_devno;

static struct skd_device *skd_construct(struct pci_dev *pdev)
{
        struct skd_device *skdev;
        int blk_major = skd_major;
        size_t size;
        int rc;

        skdev = kzalloc(sizeof(*skdev), GFP_KERNEL);

        if (!skdev) {
                dev_err(&pdev->dev, "memory alloc failure\n");
                return NULL;
        }

        skdev->state = SKD_DRVR_STATE_LOAD;
        skdev->pdev = pdev;
        skdev->devno = skd_next_devno++;
        skdev->major = blk_major;
        skdev->dev_max_queue_depth = 0;

        skdev->num_req_context = skd_max_queue_depth;
        skdev->num_fitmsg_context = skd_max_queue_depth;
        skdev->cur_max_queue_depth = 1;
        skdev->queue_low_water_mark = 1;
        skdev->proto_ver = 99;
        skdev->sgs_per_request = skd_sgs_per_request;
        skdev->dbg_level = skd_dbg_level;

        spin_lock_init(&skdev->lock);

        INIT_WORK(&skdev->start_queue, skd_start_queue);
        INIT_WORK(&skdev->completion_worker, skd_completion_worker);

        size = max(SKD_N_FITMSG_BYTES, SKD_N_SPECIAL_FITMSG_BYTES);
        skdev->msgbuf_cache = kmem_cache_create("skd-msgbuf", size, 0,
                                                SLAB_HWCACHE_ALIGN, NULL);
        if (!skdev->msgbuf_cache)
                goto err_out;
        WARN_ONCE(kmem_cache_size(skdev->msgbuf_cache) < size,
                  "skd-msgbuf: %d < %zd\n",
                  kmem_cache_size(skdev->msgbuf_cache), size);
        size = skd_sgs_per_request * sizeof(struct fit_sg_descriptor);
        skdev->sglist_cache = kmem_cache_create("skd-sglist", size, 0,
                                                SLAB_HWCACHE_ALIGN, NULL);
        if (!skdev->sglist_cache)
                goto err_out;
        WARN_ONCE(kmem_cache_size(skdev->sglist_cache) < size,
                  "skd-sglist: %d < %zd\n",
                  kmem_cache_size(skdev->sglist_cache), size);
        size = SKD_N_INTERNAL_BYTES;
        skdev->databuf_cache = kmem_cache_create("skd-databuf", size, 0,
                                                 SLAB_HWCACHE_ALIGN, NULL);
        if (!skdev->databuf_cache)
                goto err_out;
        WARN_ONCE(kmem_cache_size(skdev->databuf_cache) < size,
                  "skd-databuf: %d < %zd\n",
                  kmem_cache_size(skdev->databuf_cache), size);

        dev_dbg(&skdev->pdev->dev, "skcomp\n");
        rc = skd_cons_skcomp(skdev);
        if (rc < 0)
                goto err_out;

        dev_dbg(&skdev->pdev->dev, "skmsg\n");
        rc = skd_cons_skmsg(skdev);
        if (rc < 0)
                goto err_out;

        dev_dbg(&skdev->pdev->dev, "sksb\n");
        rc = skd_cons_sksb(skdev);
        if (rc < 0)
                goto err_out;

        dev_dbg(&skdev->pdev->dev, "disk\n");
        rc = skd_cons_disk(skdev);
        if (rc < 0)
                goto err_out;

        dev_dbg(&skdev->pdev->dev, "VICTORY\n");
        return skdev;

err_out:
        dev_dbg(&skdev->pdev->dev, "construct failed\n");
        skd_destruct(skdev);
        return NULL;
}

/*
 *****************************************************************************
 * DESTRUCT (FREE)
 *****************************************************************************
 */

static void skd_free_skcomp(struct skd_device *skdev)
{
        if (skdev->skcomp_table)
                dma_free_coherent(&skdev->pdev->dev, SKD_SKCOMP_SIZE,
                                  skdev->skcomp_table, skdev->cq_dma_address);

        skdev->skcomp_table = NULL;
        skdev->cq_dma_address = 0;
}

static void skd_free_skmsg(struct skd_device *skdev)
{
        u32 i;

        if (skdev->skmsg_table == NULL)
                return;

        for (i = 0; i < skdev->num_fitmsg_context; i++) {
                struct skd_fitmsg_context *skmsg;

                skmsg = &skdev->skmsg_table[i];

                if (skmsg->msg_buf != NULL) {