drivers/mmc/mmc_queue.c

   1 /*
   2  *  linux/drivers/mmc/mmc_queue.c
   3  *
   4  *  Copyright (C) 2003 Russell King, All Rights Reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  */
  11 #include <linux/module.h>
  12 #include <linux/blkdev.h>
  13
  14 #include <linux/mmc/card.h>
  15 #include <linux/mmc/host.h>
  16 #include "mmc_queue.h"
  17
  18 #define MMC_QUEUE_EXIT          (1 << 0)
  19 #define MMC_QUEUE_SUSPENDED     (1 << 1)
  20
  21 /*
  22  * Prepare a MMC request.  Essentially, this means passing the
  23  * preparation off to the media driver.  The media driver will
  24  * create a mmc_io_request in req->special.
  25  */
  26 static int mmc_prep_request(struct request_queue *q, struct request *req)
  27 {
  28         struct mmc_queue *mq = q->queuedata;
  29         int ret = BLKPREP_KILL;
  30
  31         if (req->flags & REQ_SPECIAL) {
  32                 /*
  33                  * Special commands already have the command
  34                  * blocks already setup in req->special.
  35                  */
  36                 BUG_ON(!req->special);
  37
  38                 ret = BLKPREP_OK;
  39         } else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
  40                 /*
  41                  * Block I/O requests need translating according
  42                  * to the protocol.
  43                  */
  44                 ret = mq->prep_fn(mq, req);
  45         } else {
  46                 /*
  47                  * Everything else is invalid.
  48                  */
  49                 blk_dump_rq_flags(req, "MMC bad request");
  50         }
  51
  52         if (ret == BLKPREP_OK)
  53                 req->flags |= REQ_DONTPREP;
  54
  55         return ret;
  56 }
  57
  58 static int mmc_queue_thread(void *d)
  59 {
  60         struct mmc_queue *mq = d;
  61         struct request_queue *q = mq->queue;
  62         DECLARE_WAITQUEUE(wait, current);
  63
  64         /*
  65          * Set iothread to ensure that we aren't put to sleep by
  66          * the process freezing.  We handle suspension ourselves.
  67          */
  68         current->flags |= PF_MEMALLOC|PF_NOFREEZE;
  69
  70         daemonize("mmcqd");
  71
  72         complete(&mq->thread_complete);
  73
  74         down(&mq->thread_sem);
  75         add_wait_queue(&mq->thread_wq, &wait);
  76         do {
  77                 struct request *req = NULL;
  78
  79                 spin_lock_irq(q->queue_lock);
  80                 set_current_state(TASK_INTERRUPTIBLE);
  81                 if (!blk_queue_plugged(q))
  82                         req = elv_next_request(q);
  83                 mq->req = req;
  84                 spin_unlock_irq(q->queue_lock);
  85
  86                 if (!req) {
  87                         if (mq->flags & MMC_QUEUE_EXIT)
  88                                 break;
  89                         up(&mq->thread_sem);
  90                         schedule();
  91                         down(&mq->thread_sem);
  92                         continue;
  93                 }
  94                 set_current_state(TASK_RUNNING);
  95
  96                 mq->issue_fn(mq, req);
  97         } while (1);
  98         remove_wait_queue(&mq->thread_wq, &wait);
  99         up(&mq->thread_sem);
 100
 101         complete_and_exit(&mq->thread_complete, 0);
 102         return 0;
 103 }
 104
 105 /*
 106  * Generic MMC request handler.  This is called for any queue on a
 107  * particular host.  When the host is not busy, we look for a request
 108  * on any queue on this host, and attempt to issue it.  This may
 109  * not be the queue we were asked to process.
 110  */
 111 static void mmc_request(request_queue_t *q)
 112 {
 113         struct mmc_queue *mq = q->queuedata;
 114
 115         if (!mq->req)
 116                 wake_up(&mq->thread_wq);
 117 }
 118
 119 /**
 120  * mmc_init_queue - initialise a queue structure.
 121  * @mq: mmc queue
 122  * @card: mmc card to attach this queue
 123  * @lock: queue lock
 124  *
 125  * Initialise a MMC card request queue.
 126  */
 127 int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, spinlock_t *lock)
 128 {
 129         struct mmc_host *host = card->host;
 130         u64 limit = BLK_BOUNCE_HIGH;
 131         int ret;
 132
 133         if (host->dev->dma_mask && *host->dev->dma_mask)
 134                 limit = *host->dev->dma_mask;
 135
 136         mq->card = card;
 137         mq->queue = blk_init_queue(mmc_request, lock);
 138         if (!mq->queue)
 139                 return -ENOMEM;
 140
 141         blk_queue_prep_rq(mq->queue, mmc_prep_request);
 142         blk_queue_bounce_limit(mq->queue, limit);
 143         blk_queue_max_sectors(mq->queue, host->max_sectors);
 144         blk_queue_max_phys_segments(mq->queue, host->max_phys_segs);
 145         blk_queue_max_hw_segments(mq->queue, host->max_hw_segs);
 146         blk_queue_max_segment_size(mq->queue, host->max_seg_size);
 147
 148         mq->queue->queuedata = mq;
 149         mq->req = NULL;
 150
 151         mq->sg = kmalloc(sizeof(struct scatterlist) * host->max_phys_segs,
 152                          GFP_KERNEL);
 153         if (!mq->sg) {
 154                 ret = -ENOMEM;
 155                 goto cleanup;
 156         }
 157
 158         init_completion(&mq->thread_complete);
 159         init_waitqueue_head(&mq->thread_wq);
 160         init_MUTEX(&mq->thread_sem);
 161
 162         ret = kernel_thread(mmc_queue_thread, mq, CLONE_KERNEL);
 163         if (ret >= 0) {
 164                 wait_for_completion(&mq->thread_complete);
 165                 init_completion(&mq->thread_complete);
 166                 ret = 0;
 167                 goto out;
 168         }
 169
 170  cleanup:
 171         kfree(mq->sg);
 172         mq->sg = NULL;
 173
 174         blk_cleanup_queue(mq->queue);
 175  out:
 176         return ret;
 177 }
 178 EXPORT_SYMBOL(mmc_init_queue);
 179
 180 void mmc_cleanup_queue(struct mmc_queue *mq)
 181 {
 182         mq->flags |= MMC_QUEUE_EXIT;
 183         wake_up(&mq->thread_wq);
 184         wait_for_completion(&mq->thread_complete);
 185
 186         kfree(mq->sg);
 187         mq->sg = NULL;
 188
 189         blk_cleanup_queue(mq->queue);
 190
 191         mq->card = NULL;
 192 }
 193 EXPORT_SYMBOL(mmc_cleanup_queue);
 194
 195 /**
 196  * mmc_queue_suspend - suspend a MMC request queue
 197  * @mq: MMC queue to suspend
 198  *
 199  * Stop the block request queue, and wait for our thread to
 200  * complete any outstanding requests.  This ensures that we
 201  * won't suspend while a request is being processed.
 202  */
 203 void mmc_queue_suspend(struct mmc_queue *mq)
 204 {
 205         request_queue_t *q = mq->queue;
 206         unsigned long flags;
 207
 208         if (!(mq->flags & MMC_QUEUE_SUSPENDED)) {
 209                 mq->flags |= MMC_QUEUE_SUSPENDED;
 210
 211                 spin_lock_irqsave(q->queue_lock, flags);
 212                 blk_stop_queue(q);
 213                 spin_unlock_irqrestore(q->queue_lock, flags);
 214
 215                 down(&mq->thread_sem);
 216         }
 217 }
 218 EXPORT_SYMBOL(mmc_queue_suspend);
 219
 220 /**
 221  * mmc_queue_resume - resume a previously suspended MMC request queue
 222  * @mq: MMC queue to resume
 223  */
 224 void mmc_queue_resume(struct mmc_queue *mq)
 225 {
 226         request_queue_t *q = mq->queue;
 227         unsigned long flags;
 228
 229         if (mq->flags & MMC_QUEUE_SUSPENDED) {
 230                 mq->flags &= ~MMC_QUEUE_SUSPENDED;
 231
 232                 up(&mq->thread_sem);
 233
 234                 spin_lock_irqsave(q->queue_lock, flags);
 235                 blk_start_queue(q);
 236                 spin_unlock_irqrestore(q->queue_lock, flags);
 237         }
 238 }
 239 EXPORT_SYMBOL(mmc_queue_resume);