/*
 *  linux/drivers/mmc/card/queue.c
 *
 *  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/mmc/card.h>
#include <linux/mmc/host.h>
#include "queue.h"

#define MMC_QUEUE_BOUNCESZ      65536

#define MMC_QUEUE_SUSPENDED     (1 << 0)

/*
 * Prepare a MMC request. This just filters out odd stuff.
 */
static int mmc_prep_request(struct request_queue *q, struct request *req)
{
        /*
         * We only like normal block requests and discards.
         */
        if (req->cmd_type != REQ_TYPE_FS && !(req->cmd_flags & REQ_DISCARD)) {
                blk_dump_rq_flags(req, "MMC bad request");
                return BLKPREP_KILL;
        }

        req->cmd_flags |= REQ_DONTPREP;

        return BLKPREP_OK;
}

static int mmc_queue_thread(void *d)
{
        struct mmc_queue *mq = d;
        struct request_queue *q = mq->queue;

        current->flags |= PF_MEMALLOC;

        down(&mq->thread_sem);
        do {
                struct request *req = NULL;
                struct mmc_queue_req *tmp;

                spin_lock_irq(q->queue_lock);
                set_current_state(TASK_INTERRUPTIBLE);
                req = blk_fetch_request(q);
                mq->mqrq_cur->req = req;
                spin_unlock_irq(q->queue_lock);

                if (req || mq->mqrq_prev->req) {
                        set_current_state(TASK_RUNNING);
                        mq->issue_fn(mq, req);
                } else {
                        if (kthread_should_stop()) {
                                set_current_state(TASK_RUNNING);
                                break;
                        }
                        up(&mq->thread_sem);
                        schedule();
                        down(&mq->thread_sem);
                }

                /* Current request becomes previous request and vice versa. */
                mq->mqrq_prev->brq.mrq.data = NULL;
                mq->mqrq_prev->req = NULL;
                tmp = mq->mqrq_prev;
                mq->mqrq_prev = mq->mqrq_cur;
                mq->mqrq_cur = tmp;
        } 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(struct request_queue *q)
{
        struct mmc_queue *mq = q->queuedata;
        struct request *req;

        if (!mq) {
                while ((req = blk_fetch_request(q)) != NULL) {
                        req->cmd_flags |= REQ_QUIET;
                        __blk_end_request_all(req, -EIO);
                }
                return;
        }

        if (!mq->mqrq_cur->req && !mq->mqrq_prev->req)
                wake_up_process(mq->thread);
}

struct scatterlist *mmc_alloc_sg(int sg_len, int *err)
{
        struct scatterlist *sg;

        sg = kmalloc(sizeof(struct scatterlist)*sg_len, GFP_KERNEL);
        if (!sg)
                *err = -ENOMEM;
        else {
                *err = 0;
                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);
        q->limits.max_discard_sectors = max_discard;
        if (card->erased_byte == 0)
                q->limits.discard_zeroes_data = 1;
        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_SECDISCARD, q);
}

/**
 * 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;
        struct mmc_queue_req *mqrq_cur = &mq->mqrq[0];
        struct mmc_queue_req *mqrq_prev = &mq->mqrq[1];

        if (mmc_dev(host)->dma_mask && *mmc_dev(host)->dma_mask)
                limit = *mmc_dev(host)->dma_mask;

        mq->card = card;
        mq->queue = blk_init_queue(mmc_request, lock);
        if (!mq->queue)
                return -ENOMEM;

        memset(&mq->mqrq_cur, 0, sizeof(mq->mqrq_cur));
        memset(&mq->mqrq_prev, 0, sizeof(mq->mqrq_prev));
        mq->mqrq_cur = mqrq_cur;
        mq->mqrq_prev = mqrq_prev;
        mq->queue->queuedata = mq;

        blk_queue_prep_rq(mq->queue, mmc_prep_request);
        queue_flag_set_unlocked(QUEUE_FLAG_NONROT, mq->queue);
        if (mmc_can_erase(card))
                mmc_queue_setup_discard(mq->queue, card);

#ifdef CONFIG_MMC_BLOCK_BOUNCE
        if (host->max_segs == 1) {
                unsigned int bouncesz;

                bouncesz = MMC_QUEUE_BOUNCESZ;

                if (bouncesz > host->max_req_size)
                        bouncesz = host->max_req_size;
                if (bouncesz > host->max_seg_size)
                        bouncesz = host->max_seg_size;
                if (bouncesz > (host->max_blk_count * 512))
                        bouncesz = host->max_blk_count * 512;

                if (bouncesz > 512) {
                        mqrq_cur->bounce_buf = kmalloc(bouncesz, GFP_KERNEL);
                        if (!mqrq_cur->bounce_buf) {
                                printk(KERN_WARNING "%s: unable to "
                                        "allocate bounce cur buffer\n",
                                        mmc_card_name(card));
                        }
                        mqrq_prev->bounce_buf = kmalloc(bouncesz, GFP_KERNEL);
                        if (!mqrq_prev->bounce_buf) {
                                printk(KERN_WARNING "%s: unable to "
                                        "allocate bounce prev buffer\n",
                                        mmc_card_name(card));
                                kfree(mqrq_cur->bounce_buf);
                                mqrq_cur->bounce_buf = NULL;
                        }
                }

                if (mqrq_cur->bounce_buf && mqrq_prev->bounce_buf) {
                        blk_queue_bounce_limit(mq->queue, BLK_BOUNCE_ANY);
                        blk_queue_max_hw_sectors(mq->queue, bouncesz / 512);
                        blk_queue_max_segments(mq->queue, bouncesz / 512);
                        blk_queue_max_segment_size(mq->queue, bouncesz);

                        mqrq_cur->sg = mmc_alloc_sg(1, &ret);
                        if (ret)
                                goto cleanup_queue;

                        mqrq_cur->bounce_sg =
                                mmc_alloc_sg(bouncesz / 512, &ret);
                        if (ret)
                                goto cleanup_queue;

                        mqrq_prev->sg = mmc_alloc_sg(1, &ret);
                        if (ret)
                                goto cleanup_queue;

                        mqrq_prev->bounce_sg =
                                mmc_alloc_sg(bouncesz / 512, &ret);
                        if (ret)
                                goto cleanup_queue;
                }
        }
#endif

        if (!mqrq_cur->bounce_buf && !mqrq_prev->bounce_buf) {
                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);

                mqrq_cur->sg = mmc_alloc_sg(host->max_segs, &ret);
                if (ret)
                        goto cleanup_queue;


                mqrq_prev->sg = mmc_alloc_sg(host->max_segs, &ret);
                if (ret)
                        goto cleanup_queue;
        }

        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 free_bounce_sg;
        }

        return 0;
 free_bounce_sg:
        kfree(mqrq_cur->bounce_sg);
        mqrq_cur->bounce_sg = NULL;
        kfree(mqrq_prev->bounce_sg);
        mqrq_prev->bounce_sg = NULL;

 cleanup_queue:
        kfree(mqrq_cur->sg);
        mqrq_cur->sg = NULL;
        kfree(mqrq_cur->bounce_buf);
        mqrq_cur->bounce_buf = NULL;

        kfree(mqrq_prev->sg);
        mqrq_prev->sg = NULL;
        kfree(mqrq_prev->bounce_buf);
        mqrq_prev->bounce_buf = NULL;

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

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

        /* 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);

        kfree(mqrq_cur->bounce_sg);
        mqrq_cur->bounce_sg = NULL;

        kfree(mqrq_cur->sg);
        mqrq_cur->sg = NULL;

        kfree(mqrq_cur->bounce_buf);
        mqrq_cur->bounce_buf = NULL;

        kfree(mqrq_prev->bounce_sg);
        mqrq_prev->bounce_sg = NULL;

        kfree(mqrq_prev->sg);
        mqrq_prev->sg = NULL;

        kfree(mqrq_prev->bounce_buf);
        mqrq_prev->bounce_buf = NULL;

        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->flags & MMC_QUEUE_SUSPENDED)) {
                mq->flags |= MMC_QUEUE_SUSPENDED;

                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->flags & MMC_QUEUE_SUSPENDED) {
                mq->flags &= ~MMC_QUEUE_SUSPENDED;

                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)
{
        unsigned int sg_len;
        size_t buflen;
        struct scatterlist *sg;
        int i;

        if (!mqrq->bounce_buf)
                return blk_rq_map_sg(mq->queue, mqrq->req, mqrq->sg);

        BUG_ON(!mqrq->bounce_sg);

        sg_len = blk_rq_map_sg(mq->queue, mqrq->req, mqrq->bounce_sg);

        mqrq->bounce_sg_len = sg_len;

        buflen = 0;
        for_each_sg(mqrq->bounce_sg, sg, sg_len, i)
                buflen += sg->length;

        sg_init_one(mqrq->sg, mqrq->bounce_buf, buflen);

        return 1;
}

/*
 * If writing, bounce the data to the buffer before the request
 * is sent to the host driver
 */
void mmc_queue_bounce_pre(struct mmc_queue_req *mqrq)
{
        if (!mqrq->bounce_buf)
                return;

        if (rq_data_dir(mqrq->req) != WRITE)
                return;

        sg_copy_to_buffer(mqrq->bounce_sg, mqrq->bounce_sg_len,
                mqrq->bounce_buf, mqrq->sg[0].length);
}

/*
 * If reading, bounce the data from the buffer after the request
 * has been handled by the host driver
 */
void mmc_queue_bounce_post(struct mmc_queue_req *mqrq)
{
        if (!mqrq->bounce_buf)
                return;

        if (rq_data_dir(mqrq->req) != READ)
                return;

        sg_copy_from_buffer(mqrq->bounce_sg, mqrq->bounce_sg_len,
                mqrq->bounce_buf, mqrq->sg[0].length);
}