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                         mq->req = req = elv_next_request(q);
  83                 spin_unlock_irq(q->queue_lock);
  84
  85                 if (!req) {
  86                         if (mq->flags & MMC_QUEUE_EXIT)
  87                                 break;
  88                         up(&mq->thread_sem);
  89                         schedule();
  90                         down(&mq->thread_sem);
  91                         continue;
  92                 }
  93                 set_current_state(TASK_RUNNING);
  94
  95                 mq->issue_fn(mq, req);
  96         } while (1);
  97         remove_wait_queue(&mq->thread_wq, &wait);
  98         up(&mq->thread_sem);
  99
 100         complete_and_exit(&mq->thread_complete, 0);
 101         return 0;
 102 }
 103
 104 /*
 105  * Generic MMC request handler.  This is called for any queue on a
 106  * particular host.  When the host is not busy, we look for a request
 107  * on any queue on this host, and attempt to issue it.  This may
 108  * not be the queue we were asked to process.
 109  */
 110 static void mmc_request(request_queue_t *q)
 111 {
 112         struct mmc_queue *mq = q->queuedata;
 113
 114         if (!mq->req)
 115                 wake_up(&mq->thread_wq);
 116 }
 117
 118 /**
 119  * mmc_init_queue - initialise a queue structure.
 120  * @mq: mmc queue
 121  * @card: mmc card to attach this queue
 122  * @lock: queue lock
 123  *
 124  * Initialise a MMC card request queue.
 125  */
 126 int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, spinlock_t *lock)
 127 {
 128         struct mmc_host *host = card->host;
 129         u64 limit = BLK_BOUNCE_HIGH;
 130         int ret;
 131
 132         if (host->dev->dma_mask && *host->dev->dma_mask)
 133                 limit = *host->dev->dma_mask;
 134
 135         mq->card = card;
 136         mq->queue = blk_init_queue(mmc_request, lock);
 137         if (!mq->queue)
 138                 return -ENOMEM;
 139
 140         blk_queue_prep_rq(mq->queue, mmc_prep_request);
 141         blk_queue_bounce_limit(mq->queue, limit);
 142         blk_queue_max_sectors(mq->queue, host->max_sectors);
 143         blk_queue_max_phys_segments(mq->queue, host->max_phys_segs);
 144         blk_queue_max_hw_segments(mq->queue, host->max_hw_segs);
 145         blk_queue_max_segment_size(mq->queue, host->max_seg_size);
 146
 147         mq->queue->queuedata = mq;
 148         mq->req = NULL;
 149
 150         mq->sg = kmalloc(sizeof(struct scatterlist) * host->max_phys_segs,
 151                          GFP_KERNEL);
 152         if (!mq->sg) {
 153                 ret = -ENOMEM;
 154                 goto cleanup;
 155         }
 156
 157         init_completion(&mq->thread_complete);
 158         init_waitqueue_head(&mq->thread_wq);
 159         init_MUTEX(&mq->thread_sem);
 160
 161         ret = kernel_thread(mmc_queue_thread, mq, CLONE_KERNEL);
 162         if (ret >= 0) {
 163                 wait_for_completion(&mq->thread_complete);
 164                 init_completion(&mq->thread_complete);
 165                 ret = 0;
 166                 goto out;
 167         }
 168
 169  cleanup:
 170         kfree(mq->sg);
 171         mq->sg = NULL;
 172
 173         blk_cleanup_queue(mq->queue);
 174  out:
 175         return ret;
 176 }
 177 EXPORT_SYMBOL(mmc_init_queue);
 178
 179 void mmc_cleanup_queue(struct mmc_queue *mq)
 180 {
 181         mq->flags |= MMC_QUEUE_EXIT;
 182         wake_up(&mq->thread_wq);
 183         wait_for_completion(&mq->thread_complete);
 184
 185         kfree(mq->sg);
 186         mq->sg = NULL;
 187
 188         blk_cleanup_queue(mq->queue);
 189
 190         mq->card = NULL;
 191 }
 192 EXPORT_SYMBOL(mmc_cleanup_queue);
 193
 194 /**
 195  * mmc_queue_suspend - suspend a MMC request queue
 196  * @mq: MMC queue to suspend
 197  *
 198  * Stop the block request queue, and wait for our thread to
 199  * complete any outstanding requests.  This ensures that we
 200  * won't suspend while a request is being processed.
 201  */
 202 void mmc_queue_suspend(struct mmc_queue *mq)
 203 {
 204         request_queue_t *q = mq->queue;
 205         unsigned long flags;
 206
 207         if (!(mq->flags & MMC_QUEUE_SUSPENDED)) {
 208                 mq->flags |= MMC_QUEUE_SUSPENDED;
 209
 210                 spin_lock_irqsave(q->queue_lock, flags);
 211                 blk_stop_queue(q);
 212                 spin_unlock_irqrestore(q->queue_lock, flags);
 213
 214                 down(&mq->thread_sem);
 215         }
 216 }
 217 EXPORT_SYMBOL(mmc_queue_suspend);
 218
 219 /**
 220  * mmc_queue_resume - resume a previously suspended MMC request queue
 221  * @mq: MMC queue to resume
 222  */
 223 void mmc_queue_resume(struct mmc_queue *mq)
 224 {
 225         request_queue_t *q = mq->queue;
 226         unsigned long flags;
 227
 228         if (mq->flags & MMC_QUEUE_SUSPENDED) {
 229                 mq->flags &= ~MMC_QUEUE_SUSPENDED;
 230
 231                 up(&mq->thread_sem);
 232
 233                 spin_lock_irqsave(q->queue_lock, flags);
 234                 blk_start_queue(q);
 235                 spin_unlock_irqrestore(q->queue_lock, flags);
 236         }
 237 }
 238 EXPORT_SYMBOL(mmc_queue_resume);