/*
 *  Copyright (C) 2003 Russell King, All Rights Reserved.
 *  Copyright 2006-2007 Pierre Ossman
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/scatterlist.h>
#include <linux/dma-mapping.h>

#include <linux/mmc/card.h>
#include <linux/mmc/host.h>

#include "queue.h"
#include "block.h"
#include "core.h"
#include "card.h"
#include "host.h"

static inline bool mmc_cqe_dcmd_busy(struct mmc_queue *mq)
{
        /* Allow only 1 DCMD at a time */
        return mq->in_flight[MMC_ISSUE_DCMD];
}

void mmc_cqe_check_busy(struct mmc_queue *mq)
{
        if ((mq->cqe_busy & MMC_CQE_DCMD_BUSY) && !mmc_cqe_dcmd_busy(mq))
                mq->cqe_busy &= ~MMC_CQE_DCMD_BUSY;

        mq->cqe_busy &= ~MMC_CQE_QUEUE_FULL;
}

static inline bool mmc_cqe_can_dcmd(struct mmc_host *host)
{
        return host->caps2 & MMC_CAP2_CQE_DCMD;
}

static enum mmc_issue_type mmc_cqe_issue_type(struct mmc_host *host,
                                              struct request *req)
{
        switch (req_op(req)) {
        case REQ_OP_DRV_IN:
        case REQ_OP_DRV_OUT:
        case REQ_OP_DISCARD:
        case REQ_OP_SECURE_ERASE:
                return MMC_ISSUE_SYNC;
        case REQ_OP_FLUSH:
                return mmc_cqe_can_dcmd(host) ? MMC_ISSUE_DCMD : MMC_ISSUE_SYNC;
        default:
                return MMC_ISSUE_ASYNC;
        }
}

enum mmc_issue_type mmc_issue_type(struct mmc_queue *mq, struct request *req)
{
        struct mmc_host *host = mq->card->host;

        if (mq->use_cqe)
                return mmc_cqe_issue_type(host, req);

        if (req_op(req) == REQ_OP_READ || req_op(req) == REQ_OP_WRITE)
                return MMC_ISSUE_ASYNC;

        return MMC_ISSUE_SYNC;
}

static void __mmc_cqe_recovery_notifier(struct mmc_queue *mq)
{
        if (!mq->recovery_needed) {
                mq->recovery_needed = true;
                schedule_work(&mq->recovery_work);
        }
}

void mmc_cqe_recovery_notifier(struct mmc_request *mrq)
{
        struct mmc_queue_req *mqrq = container_of(mrq, struct mmc_queue_req,
                                                  brq.mrq);
        struct request *req = mmc_queue_req_to_req(mqrq);
        struct request_queue *q = req->q;
        struct mmc_queue *mq = q->queuedata;
        unsigned long flags;

        spin_lock_irqsave(&mq->lock, flags);
        __mmc_cqe_recovery_notifier(mq);
        spin_unlock_irqrestore(&mq->lock, flags);
}

static enum blk_eh_timer_return mmc_cqe_timed_out(struct request *req)
{
        struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
        struct mmc_request *mrq = &mqrq->brq.mrq;
        struct mmc_queue *mq = req->q->queuedata;
        struct mmc_host *host = mq->card->host;
        enum mmc_issue_type issue_type = mmc_issue_type(mq, req);
        bool recovery_needed = false;

        switch (issue_type) {
        case MMC_ISSUE_ASYNC:
        case MMC_ISSUE_DCMD:
                if (host->cqe_ops->cqe_timeout(host, mrq, &recovery_needed)) {
                        if (recovery_needed)
                                __mmc_cqe_recovery_notifier(mq);
                        return BLK_EH_RESET_TIMER;
                }
                /* No timeout (XXX: huh? comment doesn't make much sense) */
                blk_mq_complete_request(req);
                return BLK_EH_DONE;
        default:
                /* Timeout is handled by mmc core */
                return BLK_EH_RESET_TIMER;
        }
}

static enum blk_eh_timer_return mmc_mq_timed_out(struct request *req,
                                                 bool reserved)
{
        struct request_queue *q = req->q;
        struct mmc_queue *mq = q->queuedata;
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&mq->lock, flags);

        if (mq->recovery_needed || !mq->use_cqe)
                ret = BLK_EH_RESET_TIMER;
        else
                ret = mmc_cqe_timed_out(req);

        spin_unlock_irqrestore(&mq->lock, flags);

        return ret;
}

static void mmc_mq_recovery_handler(struct work_struct *work)
{
        struct mmc_queue *mq = container_of(work, struct mmc_queue,
                                            recovery_work);
        struct request_queue *q = mq->queue;

        mmc_get_card(mq->card, &mq->ctx);

        mq->in_recovery = true;

        if (mq->use_cqe)
                mmc_blk_cqe_recovery(mq);
        else
                mmc_blk_mq_recovery(mq);

        mq->in_recovery = false;

        spin_lock_irq(&mq->lock);
        mq->recovery_needed = false;
        spin_unlock_irq(&mq->lock);

        mmc_put_card(mq->card, &mq->ctx);

        blk_mq_run_hw_queues(q, true);
}

static struct scatterlist *mmc_alloc_sg(int sg_len, gfp_t gfp)
{
        struct scatterlist *sg;

        sg = kmalloc_array(sg_len, sizeof(*sg), gfp);
        if (sg)
                sg_init_table(sg, sg_len);

        return sg;
}

static void mmc_queue_setup_discard(struct request_queue *q,
                                    struct mmc_card *card)
{
        unsigned max_discard;

        max_discard = mmc_calc_max_discard(card);
        if (!max_discard)
                return;

        blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
        blk_queue_max_discard_sectors(q, max_discard);
        q->limits.discard_granularity = card->pref_erase << 9;
        /* granularity must not be greater than max. discard */
        if (card->pref_erase > max_discard)
                q->limits.discard_granularity = 0;
        if (mmc_can_secure_erase_trim(card))
                blk_queue_flag_set(QUEUE_FLAG_SECERASE, q);
}

/**
 * mmc_init_request() - initialize the MMC-specific per-request data
 * @q: the request queue
 * @req: the request
 * @gfp: memory allocation policy
 */
static int __mmc_init_request(struct mmc_queue *mq, struct request *req,
                              gfp_t gfp)
{
        struct mmc_queue_req *mq_rq = req_to_mmc_queue_req(req);
        struct mmc_card *card = mq->card;
        struct mmc_host *host = card->host;

        mq_rq->sg = mmc_alloc_sg(host->max_segs, gfp);
        if (!mq_rq->sg)
                return -ENOMEM;

        return 0;
}

static void mmc_exit_request(struct request_queue *q, struct request *req)
{
        struct mmc_queue_req *mq_rq = req_to_mmc_queue_req(req);

        kfree(mq_rq->sg);
        mq_rq->sg = NULL;
}

static int mmc_mq_init_request(struct blk_mq_tag_set *set, struct request *req,
                               unsigned int hctx_idx, unsigned int numa_node)
{
        return __mmc_init_request(set->driver_data, req, GFP_KERNEL);
}

static void mmc_mq_exit_request(struct blk_mq_tag_set *set, struct request *req,
                                unsigned int hctx_idx)
{
        struct mmc_queue *mq = set->driver_data;

        mmc_exit_request(mq->queue, req);
}

static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
                                    const struct blk_mq_queue_data *bd)
{
        struct request *req = bd->rq;
        struct request_queue *q = req->q;
        struct mmc_queue *mq = q->queuedata;
        struct mmc_card *card = mq->card;
        struct mmc_host *host = card->host;
        enum mmc_issue_type issue_type;
        enum mmc_issued issued;
        bool get_card, cqe_retune_ok;
        int ret;

        if (mmc_card_removed(mq->card)) {
                req->rq_flags |= RQF_QUIET;
                return BLK_STS_IOERR;
        }

        issue_type = mmc_issue_type(mq, req);

        spin_lock_irq(&mq->lock);

        if (mq->recovery_needed || mq->busy) {
                spin_unlock_irq(&mq->lock);
                return BLK_STS_RESOURCE;
        }

        switch (issue_type) {
        case MMC_ISSUE_DCMD:
                if (mmc_cqe_dcmd_busy(mq)) {
                        mq->cqe_busy |= MMC_CQE_DCMD_BUSY;
                        spin_unlock_irq(&mq->lock);
                        return BLK_STS_RESOURCE;
                }
                break;
        case MMC_ISSUE_ASYNC:
                break;
        default:
                /*
                 * Timeouts are handled by mmc core, and we don't have a host
                 * API to abort requests, so we can't handle the timeout anyway.
                 * However, when the timeout happens, blk_mq_complete_request()
                 * no longer works (to stop the request disappearing under us).
                 * To avoid racing with that, set a large timeout.
                 */
                req->timeout = 600 * HZ;
                break;
        }

        /* Parallel dispatch of requests is not supported at the moment */
        mq->busy = true;

        mq->in_flight[issue_type] += 1;
        get_card = (mmc_tot_in_flight(mq) == 1);
        cqe_retune_ok = (mmc_cqe_qcnt(mq) == 1);

        spin_unlock_irq(&mq->lock);

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

        if (get_card)
                mmc_get_card(card, &mq->ctx);

        if (mq->use_cqe) {
                host->retune_now = host->need_retune && cqe_retune_ok &&
                                   !host->hold_retune;
        }

        blk_mq_start_request(req);

        issued = mmc_blk_mq_issue_rq(mq, req);

        switch (issued) {
        case MMC_REQ_BUSY:
                ret = BLK_STS_RESOURCE;
                break;
        case MMC_REQ_FAILED_TO_START:
                ret = BLK_STS_IOERR;
                break;
        default:
                ret = BLK_STS_OK;
                break;
        }

        if (issued != MMC_REQ_STARTED) {
                bool put_card = false;

                spin_lock_irq(&mq->lock);
                mq->in_flight[issue_type] -= 1;
                if (mmc_tot_in_flight(mq) == 0)
                        put_card = true;
                mq->busy = false;
                spin_unlock_irq(&mq->lock);
                if (put_card)
                        mmc_put_card(card, &mq->ctx);
        } else {
                WRITE_ONCE(mq->busy, false);
        }

        return ret;
}

static const struct blk_mq_ops mmc_mq_ops = {
        .queue_rq       = mmc_mq_queue_rq,
        .init_request   = mmc_mq_init_request,
        .exit_request   = mmc_mq_exit_request,
        .complete       = mmc_blk_mq_complete,
        .timeout        = mmc_mq_timed_out,
};

static void mmc_setup_queue(struct mmc_queue *mq, struct mmc_card *card)
{
        struct mmc_host *host = card->host;
        u64 limit = BLK_BOUNCE_HIGH;
        unsigned block_size = 512;

        if (mmc_dev(host)->dma_mask && *mmc_dev(host)->dma_mask)
                limit = (u64)dma_max_pfn(mmc_dev(host)) << PAGE_SHIFT;

        blk_queue_flag_set(QUEUE_FLAG_NONROT, mq->queue);
        blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, mq->queue);
        if (mmc_can_erase(card))
                mmc_queue_setup_discard(mq->queue, card);

        blk_queue_bounce_limit(mq->queue, limit);
        blk_queue_max_hw_sectors(mq->queue,
                min(host->max_blk_count, host->max_req_size / 512));
        blk_queue_max_segments(mq->queue, host->max_segs);

        if (mmc_card_mmc(card))
                block_size = card->ext_csd.data_sector_size;

        blk_queue_logical_block_size(mq->queue, block_size);
        blk_queue_max_segment_size(mq->queue,
                        round_down(host->max_seg_size, block_size));

        INIT_WORK(&mq->recovery_work, mmc_mq_recovery_handler);
        INIT_WORK(&mq->complete_work, mmc_blk_mq_complete_work);

        mutex_init(&mq->complete_lock);

        init_waitqueue_head(&mq->wait);
}

/* Set queue depth to get a reasonable value for q->nr_requests */
#define MMC_QUEUE_DEPTH 64

/**
 * mmc_init_queue - initialise a queue structure.
 * @mq: mmc queue
 * @card: mmc card to attach this queue
 *
 * Initialise a MMC card request queue.
 */
int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card)
{
        struct mmc_host *host = card->host;
        int ret;

        mq->card = card;
        mq->use_cqe = host->cqe_enabled;
        
        spin_lock_init(&mq->lock);

        memset(&mq->tag_set, 0, sizeof(mq->tag_set));
        mq->tag_set.ops = &mmc_mq_ops;
        /*
         * The queue depth for CQE must match the hardware because the request
         * tag is used to index the hardware queue.
         */
        if (mq->use_cqe)
                mq->tag_set.queue_depth =
                        min_t(int, card->ext_csd.cmdq_depth, host->cqe_qdepth);
        else
                mq->tag_set.queue_depth = MMC_QUEUE_DEPTH;
        mq->tag_set.numa_node = NUMA_NO_NODE;
        mq->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING;
        mq->tag_set.nr_hw_queues = 1;
        mq->tag_set.cmd_size = sizeof(struct mmc_queue_req);
        mq->tag_set.driver_data = mq;

        ret = blk_mq_alloc_tag_set(&mq->tag_set);
        if (ret)
                return ret;

        mq->queue = blk_mq_init_queue(&mq->tag_set);
        if (IS_ERR(mq->queue)) {
                ret = PTR_ERR(mq->queue);
                goto free_tag_set;
        }

        mq->queue->queuedata = mq;
        blk_queue_rq_timeout(mq->queue, 60 * HZ);

        mmc_setup_queue(mq, card);
        return 0;

free_tag_set:
        blk_mq_free_tag_set(&mq->tag_set);
        return ret;
}

void mmc_queue_suspend(struct mmc_queue *mq)
{
        blk_mq_quiesce_queue(mq->queue);

        /*
         * The host remains claimed while there are outstanding requests, so
         * simply claiming and releasing here ensures there are none.
         */
        mmc_claim_host(mq->card->host);
        mmc_release_host(mq->card->host);
}

void mmc_queue_resume(struct mmc_queue *mq)
{
        blk_mq_unquiesce_queue(mq->queue);
}

void mmc_cleanup_queue(struct mmc_queue *mq)
{
        struct request_queue *q = mq->queue;

        /*
         * The legacy code handled the possibility of being suspended,
         * so do that here too.
         */
        if (blk_queue_quiesced(q))
                blk_mq_unquiesce_queue(q);

        blk_cleanup_queue(q);

        /*
         * A request can be completed before the next request, potentially
         * leaving a complete_work with nothing to do. Such a work item might
         * still be queued at this point. Flush it.
         */
        flush_work(&mq->complete_work);

        mq->card = NULL;
}

/*
 * Prepare the sg list(s) to be handed of to the host driver
 */
unsigned int mmc_queue_map_sg(struct mmc_queue *mq, struct mmc_queue_req *mqrq)
{
        struct request *req = mmc_queue_req_to_req(mqrq);

        return blk_rq_map_sg(mq->queue, req, mqrq->sg);
}