/*
 *  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"

/*
 * Prepare a MMC request. This just filters out odd stuff.
 */
static int mmc_prep_request(struct request_queue *q, struct request *req)
{
        struct mmc_queue *mq = q->queuedata;

        if (mq && (mmc_card_removed(mq->card) || mmc_access_rpmb(mq)))
                return BLKPREP_KILL;

        req->rq_flags |= RQF_DONTPREP;

        return BLKPREP_OK;
}

static int mmc_queue_thread(void *d)
{
        struct mmc_queue *mq = d;
        struct request_queue *q = mq->queue;
        struct mmc_context_info *cntx = &mq->card->host->context_info;

        current->flags |= PF_MEMALLOC;

        down(&mq->thread_sem);
        do {
                struct request *req;

                spin_lock_irq(q->queue_lock);
                set_current_state(TASK_INTERRUPTIBLE);
                req = blk_fetch_request(q);
                mq->asleep = false;
                cntx->is_waiting_last_req = false;
                cntx->is_new_req = false;
                if (!req) {
                        /*
                         * Dispatch queue is empty so set flags for
                         * mmc_request_fn() to wake us up.
                         */
                        if (mq->qcnt)
                                cntx->is_waiting_last_req = true;
                        else
                                mq->asleep = true;
                }
                spin_unlock_irq(q->queue_lock);

                if (req || mq->qcnt) {
                        set_current_state(TASK_RUNNING);
                        mmc_blk_issue_rq(mq, req);
                        cond_resched();
                } else {
                        if (kthread_should_stop()) {
                                set_current_state(TASK_RUNNING);
                                break;
                        }
                        up(&mq->thread_sem);
                        schedule();
                        down(&mq->thread_sem);
                }
        } while (1);
        up(&mq->thread_sem);

        return 0;
}

/*
 * Generic MMC request handler.  This is called for any queue on a
 * particular host.  When the host is not busy, we look for a request
 * on any queue on this host, and attempt to issue it.  This may
 * not be the queue we were asked to process.
 */
static void mmc_request_fn(struct request_queue *q)
{
        struct mmc_queue *mq = q->queuedata;
        struct request *req;
        struct mmc_context_info *cntx;

        if (!mq) {
                while ((req = blk_fetch_request(q)) != NULL) {
                        req->rq_flags |= RQF_QUIET;
                        __blk_end_request_all(req, BLK_STS_IOERR);
                }
                return;
        }

        cntx = &mq->card->host->context_info;

        if (cntx->is_waiting_last_req) {
                cntx->is_new_req = true;
                wake_up_interruptible(&cntx->wait);
        }

        if (mq->asleep)
                wake_up_process(mq->thread);
}

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;

        queue_flag_set_unlocked(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))
                queue_flag_set_unlocked(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 request_queue *q, struct request *req,
                            gfp_t gfp)
{
        struct mmc_queue_req *mq_rq = req_to_mmc_queue_req(req);
        struct mmc_queue *mq = q->queuedata;
        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;
}

/**
 * mmc_init_queue - initialise a queue structure.
 * @mq: mmc queue
 * @card: mmc card to attach this queue
 * @lock: queue lock
 * @subname: partition subname
 *
 * Initialise a MMC card request queue.
 */
int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
                   spinlock_t *lock, const char *subname)
{
        struct mmc_host *host = card->host;
        u64 limit = BLK_BOUNCE_HIGH;
        int ret = -ENOMEM;

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

        mq->card = card;
        mq->queue = blk_alloc_queue(GFP_KERNEL);
        if (!mq->queue)
                return -ENOMEM;
        mq->queue->queue_lock = lock;
        mq->queue->request_fn = mmc_request_fn;
        mq->queue->init_rq_fn = mmc_init_request;
        mq->queue->exit_rq_fn = mmc_exit_request;
        mq->queue->cmd_size = sizeof(struct mmc_queue_req);
        mq->queue->queuedata = mq;
        mq->qcnt = 0;
        ret = blk_init_allocated_queue(mq->queue);
        if (ret) {
                blk_cleanup_queue(mq->queue);
                return ret;
        }

        blk_queue_prep_rq(mq->queue, mmc_prep_request);
        queue_flag_set_unlocked(QUEUE_FLAG_NONROT, mq->queue);
        queue_flag_clear_unlocked(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);
        blk_queue_max_segment_size(mq->queue, host->max_seg_size);

        sema_init(&mq->thread_sem, 1);

        mq->thread = kthread_run(mmc_queue_thread, mq, "mmcqd/%d%s",
                host->index, subname ? subname : "");

        if (IS_ERR(mq->thread)) {
                ret = PTR_ERR(mq->thread);
                goto cleanup_queue;
        }

        return 0;

cleanup_queue:
        blk_cleanup_queue(mq->queue);
        return ret;
}

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

        /* Make sure the queue isn't suspended, as that will deadlock */
        mmc_queue_resume(mq);

        /* Then terminate our worker thread */
        kthread_stop(mq->thread);

        /* Empty the queue */
        spin_lock_irqsave(q->queue_lock, flags);
        q->queuedata = NULL;
        blk_start_queue(q);
        spin_unlock_irqrestore(q->queue_lock, flags);

        mq->card = NULL;
}
EXPORT_SYMBOL(mmc_cleanup_queue);

/**
 * mmc_queue_suspend - suspend a MMC request queue
 * @mq: MMC queue to suspend
 *
 * Stop the block request queue, and wait for our thread to
 * complete any outstanding requests.  This ensures that we
 * won't suspend while a request is being processed.
 */
void mmc_queue_suspend(struct mmc_queue *mq)
{
        struct request_queue *q = mq->queue;
        unsigned long flags;

        if (!mq->suspended) {
                mq->suspended |= true;

                spin_lock_irqsave(q->queue_lock, flags);
                blk_stop_queue(q);
                spin_unlock_irqrestore(q->queue_lock, flags);

                down(&mq->thread_sem);
        }
}

/**
 * mmc_queue_resume - resume a previously suspended MMC request queue
 * @mq: MMC queue to resume
 */
void mmc_queue_resume(struct mmc_queue *mq)
{
        struct request_queue *q = mq->queue;
        unsigned long flags;

        if (mq->suspended) {
                mq->suspended = false;

                up(&mq->thread_sem);

                spin_lock_irqsave(q->queue_lock, flags);
                blk_start_queue(q);
                spin_unlock_irqrestore(q->queue_lock, flags);
        }
}

/*
 * 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);
}