drivers/mmc/card/queue.c

   1 /*
   2  *  linux/drivers/mmc/queue.c
   3  *
   4  *  Copyright (C) 2003 Russell King, All Rights Reserved.
   5  *  Copyright 2006-2007 Pierre Ossman
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  */
  12 #include <linux/module.h>
  13 #include <linux/blkdev.h>
  14 #include <linux/kthread.h>
  15
  16 #include <linux/mmc/card.h>
  17 #include <linux/mmc/host.h>
  18 #include "queue.h"
  19
  20 #define MMC_QUEUE_SUSPENDED     (1 << 0)
  21
  22 /*
  23  * Prepare a MMC request. This just filters out odd stuff.
  24  */
  25 static int mmc_prep_request(struct request_queue *q, struct request *req)
  26 {
  27         /*
  28          * We only like normal block requests.
  29          */
  30         if (!blk_fs_request(req) && !blk_pc_request(req)) {
  31                 blk_dump_rq_flags(req, "MMC bad request");
  32                 return BLKPREP_KILL;
  33         }
  34
  35         req->cmd_flags |= REQ_DONTPREP;
  36
  37         return BLKPREP_OK;
  38 }
  39
  40 static int mmc_queue_thread(void *d)
  41 {
  42         struct mmc_queue *mq = d;
  43         struct request_queue *q = mq->queue;
  44
  45         /*
  46          * Set iothread to ensure that we aren't put to sleep by
  47          * the process freezing.  We handle suspension ourselves.
  48          */
  49         current->flags |= PF_MEMALLOC|PF_NOFREEZE;
  50
  51         down(&mq->thread_sem);
  52         do {
  53                 struct request *req = NULL;
  54
  55                 spin_lock_irq(q->queue_lock);
  56                 set_current_state(TASK_INTERRUPTIBLE);
  57                 if (!blk_queue_plugged(q))
  58                         req = elv_next_request(q);
  59                 mq->req = req;
  60                 spin_unlock_irq(q->queue_lock);
  61
  62                 if (!req) {
  63                         if (kthread_should_stop()) {
  64                                 set_current_state(TASK_RUNNING);
  65                                 break;
  66                         }
  67                         up(&mq->thread_sem);
  68                         schedule();
  69                         down(&mq->thread_sem);
  70                         continue;
  71                 }
  72                 set_current_state(TASK_RUNNING);
  73
  74                 mq->issue_fn(mq, req);
  75         } while (1);
  76         up(&mq->thread_sem);
  77
  78         return 0;
  79 }
  80
  81 /*
  82  * Generic MMC request handler.  This is called for any queue on a
  83  * particular host.  When the host is not busy, we look for a request
  84  * on any queue on this host, and attempt to issue it.  This may
  85  * not be the queue we were asked to process.
  86  */
  87 static void mmc_request(request_queue_t *q)
  88 {
  89         struct mmc_queue *mq = q->queuedata;
  90         struct request *req;
  91         int ret;
  92
  93         if (!mq) {
  94                 printk(KERN_ERR "MMC: killing requests for dead queue\n");
  95                 while ((req = elv_next_request(q)) != NULL) {
  96                         do {
  97                                 ret = end_that_request_chunk(req, 0,
  98                                         req->current_nr_sectors << 9);
  99                         } while (ret);
 100                 }
 101                 return;
 102         }
 103
 104         if (!mq->req)
 105                 wake_up_process(mq->thread);
 106 }
 107
 108 /**
 109  * mmc_init_queue - initialise a queue structure.
 110  * @mq: mmc queue
 111  * @card: mmc card to attach this queue
 112  * @lock: queue lock
 113  *
 114  * Initialise a MMC card request queue.
 115  */
 116 int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, spinlock_t *lock)
 117 {
 118         struct mmc_host *host = card->host;
 119         u64 limit = BLK_BOUNCE_HIGH;
 120         int ret;
 121
 122         if (mmc_dev(host)->dma_mask && *mmc_dev(host)->dma_mask)
 123                 limit = *mmc_dev(host)->dma_mask;
 124
 125         mq->card = card;
 126         mq->queue = blk_init_queue(mmc_request, lock);
 127         if (!mq->queue)
 128                 return -ENOMEM;
 129
 130         blk_queue_prep_rq(mq->queue, mmc_prep_request);
 131         blk_queue_bounce_limit(mq->queue, limit);
 132         blk_queue_max_sectors(mq->queue, host->max_req_size / 512);
 133         blk_queue_max_phys_segments(mq->queue, host->max_phys_segs);
 134         blk_queue_max_hw_segments(mq->queue, host->max_hw_segs);
 135         blk_queue_max_segment_size(mq->queue, host->max_seg_size);
 136
 137         mq->queue->queuedata = mq;
 138         mq->req = NULL;
 139
 140         mq->sg = kmalloc(sizeof(struct scatterlist) * host->max_phys_segs,
 141                          GFP_KERNEL);
 142         if (!mq->sg) {
 143                 ret = -ENOMEM;
 144                 goto cleanup_queue;
 145         }
 146
 147         init_MUTEX(&mq->thread_sem);
 148
 149         mq->thread = kthread_run(mmc_queue_thread, mq, "mmcqd");
 150         if (IS_ERR(mq->thread)) {
 151                 ret = PTR_ERR(mq->thread);
 152                 goto free_sg;
 153         }
 154
 155         return 0;
 156
 157  free_sg:
 158         kfree(mq->sg);
 159         mq->sg = NULL;
 160  cleanup_queue:
 161         blk_cleanup_queue(mq->queue);
 162         return ret;
 163 }
 164
 165 void mmc_cleanup_queue(struct mmc_queue *mq)
 166 {
 167         request_queue_t *q = mq->queue;
 168         unsigned long flags;
 169
 170         /* Mark that we should start throwing out stragglers */
 171         spin_lock_irqsave(q->queue_lock, flags);
 172         q->queuedata = NULL;
 173         spin_unlock_irqrestore(q->queue_lock, flags);
 174
 175         /* Make sure the queue isn't suspended, as that will deadlock */
 176         mmc_queue_resume(mq);
 177
 178         /* Then terminate our worker thread */
 179         kthread_stop(mq->thread);
 180
 181         kfree(mq->sg);
 182         mq->sg = NULL;
 183
 184         blk_cleanup_queue(mq->queue);
 185
 186         mq->card = NULL;
 187 }
 188 EXPORT_SYMBOL(mmc_cleanup_queue);
 189
 190 /**
 191  * mmc_queue_suspend - suspend a MMC request queue
 192  * @mq: MMC queue to suspend
 193  *
 194  * Stop the block request queue, and wait for our thread to
 195  * complete any outstanding requests.  This ensures that we
 196  * won't suspend while a request is being processed.
 197  */
 198 void mmc_queue_suspend(struct mmc_queue *mq)
 199 {
 200         request_queue_t *q = mq->queue;
 201         unsigned long flags;
 202
 203         if (!(mq->flags & MMC_QUEUE_SUSPENDED)) {
 204                 mq->flags |= MMC_QUEUE_SUSPENDED;
 205
 206                 spin_lock_irqsave(q->queue_lock, flags);
 207                 blk_stop_queue(q);
 208                 spin_unlock_irqrestore(q->queue_lock, flags);
 209
 210                 down(&mq->thread_sem);
 211         }
 212 }
 213
 214 /**
 215  * mmc_queue_resume - resume a previously suspended MMC request queue
 216  * @mq: MMC queue to resume
 217  */
 218 void mmc_queue_resume(struct mmc_queue *mq)
 219 {
 220         request_queue_t *q = mq->queue;
 221         unsigned long flags;
 222
 223         if (mq->flags & MMC_QUEUE_SUSPENDED) {
 224                 mq->flags &= ~MMC_QUEUE_SUSPENDED;
 225
 226                 up(&mq->thread_sem);
 227
 228                 spin_lock_irqsave(q->queue_lock, flags);
 229                 blk_start_queue(q);
 230                 spin_unlock_irqrestore(q->queue_lock, flags);
 231         }
 232 }
 233