queue.c

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/*
 *  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)
{
    struct mmc_queue *mq = q->queuedata;

    /*
     * 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;
    }

    if (mq && mmc_card_removed(mq->card))
        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_fn(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);
}

static 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 && !mmc_can_discard(card))
        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) || mmc_can_sanitize(card))
        queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, q);
}

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_fn, lock);
    if (!mq->queue)
        return -ENOMEM;

    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) {
                pr_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) {
                pr_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);

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);
    }
}

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);
}