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 #include <linux/kthread.h>
  14
  15 #include <linux/mmc/card.h>
  16 #include <linux/mmc/host.h>
  17 #include "mmc_queue.h"
  18
  19 #define MMC_QUEUE_SUSPENDED     (1 << 0)
  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 (blk_special_request(req)) {
  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 (blk_fs_request(req) || blk_pc_request(req)) {
  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->cmd_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
  63         /*
  64          * Set iothread to ensure that we aren't put to sleep by
  65          * the process freezing.  We handle suspension ourselves.
  66          */
  67         current->flags |= PF_MEMALLOC|PF_NOFREEZE;
  68
  69         down(&mq->thread_sem);
  70         do {
  71                 struct request *req = NULL;
  72
  73                 spin_lock_irq(q->queue_lock);
  74                 set_current_state(TASK_INTERRUPTIBLE);
  75                 if (!blk_queue_plugged(q))
  76                         req = elv_next_request(q);
  77                 mq->req = req;
  78                 spin_unlock_irq(q->queue_lock);
  79
  80                 if (!req) {
  81                         if (kthread_should_stop()) {
  82                                 set_current_state(TASK_RUNNING);
  83                                 break;
  84                         }
  85                         up(&mq->thread_sem);
  86                         schedule();
  87                         down(&mq->thread_sem);
  88                         continue;
  89                 }
  90                 set_current_state(TASK_RUNNING);
  91
  92                 mq->issue_fn(mq, req);
  93         } while (1);
  94         up(&mq->thread_sem);
  95
  96         return 0;
  97 }
  98
  99 /*
 100  * Generic MMC request handler.  This is called for any queue on a
 101  * particular host.  When the host is not busy, we look for a request
 102  * on any queue on this host, and attempt to issue it.  This may
 103  * not be the queue we were asked to process.
 104  */
 105 static void mmc_request(request_queue_t *q)
 106 {
 107         struct mmc_queue *mq = q->queuedata;
 108         struct request *req;
 109         int ret;
 110
 111         if (!mq) {
 112                 printk(KERN_ERR "MMC: killing requests for dead queue\n");
 113                 while ((req = elv_next_request(q)) != NULL) {
 114                         do {
 115                                 ret = end_that_request_chunk(req, 0,
 116                                         req->current_nr_sectors << 9);
 117                         } while (ret);
 118                 }
 119                 return;
 120         }
 121
 122         if (!mq->req)
 123                 wake_up_process(mq->thread);
 124 }
 125
 126 /**
 127  * mmc_init_queue - initialise a queue structure.
 128  * @mq: mmc queue
 129  * @card: mmc card to attach this queue
 130  * @lock: queue lock
 131  *
 132  * Initialise a MMC card request queue.
 133  */
 134 int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, spinlock_t *lock)
 135 {
 136         struct mmc_host *host = card->host;
 137         u64 limit = BLK_BOUNCE_HIGH;
 138         int ret;
 139
 140         if (mmc_dev(host)->dma_mask && *mmc_dev(host)->dma_mask)
 141                 limit = *mmc_dev(host)->dma_mask;
 142
 143         mq->card = card;
 144         mq->queue = blk_init_queue(mmc_request, lock);
 145         if (!mq->queue)
 146                 return -ENOMEM;
 147
 148         blk_queue_prep_rq(mq->queue, mmc_prep_request);
 149         blk_queue_bounce_limit(mq->queue, limit);
 150         blk_queue_max_sectors(mq->queue, host->max_req_size / 512);
 151         blk_queue_max_phys_segments(mq->queue, host->max_phys_segs);
 152         blk_queue_max_hw_segments(mq->queue, host->max_hw_segs);
 153         blk_queue_max_segment_size(mq->queue, host->max_seg_size);
 154
 155         mq->queue->queuedata = mq;
 156         mq->req = NULL;
 157
 158         mq->sg = kmalloc(sizeof(struct scatterlist) * host->max_phys_segs,
 159                          GFP_KERNEL);
 160         if (!mq->sg) {
 161                 ret = -ENOMEM;
 162                 goto cleanup_queue;
 163         }
 164
 165         init_MUTEX(&mq->thread_sem);
 166
 167         mq->thread = kthread_run(mmc_queue_thread, mq, "mmcqd");
 168         if (IS_ERR(mq->thread)) {
 169                 ret = PTR_ERR(mq->thread);
 170                 goto free_sg;
 171         }
 172
 173         return 0;
 174
 175  free_sg:
 176         kfree(mq->sg);
 177         mq->sg = NULL;
 178  cleanup_queue:
 179         blk_cleanup_queue(mq->queue);
 180         return ret;
 181 }
 182 EXPORT_SYMBOL(mmc_init_queue);
 183
 184 void mmc_cleanup_queue(struct mmc_queue *mq)
 185 {
 186         request_queue_t *q = mq->queue;
 187         unsigned long flags;
 188
 189         /* Mark that we should start throwing out stragglers */
 190         spin_lock_irqsave(q->queue_lock, flags);
 191         q->queuedata = NULL;
 192         spin_unlock_irqrestore(q->queue_lock, flags);
 193
 194         /* Then terminate our worker thread */
 195         kthread_stop(mq->thread);
 196
 197         kfree(mq->sg);
 198         mq->sg = NULL;
 199
 200         blk_cleanup_queue(mq->queue);
 201
 202         mq->card = NULL;
 203 }
 204 EXPORT_SYMBOL(mmc_cleanup_queue);
 205
 206 /**
 207  * mmc_queue_suspend - suspend a MMC request queue
 208  * @mq: MMC queue to suspend
 209  *
 210  * Stop the block request queue, and wait for our thread to
 211  * complete any outstanding requests.  This ensures that we
 212  * won't suspend while a request is being processed.
 213  */
 214 void mmc_queue_suspend(struct mmc_queue *mq)
 215 {
 216         request_queue_t *q = mq->queue;
 217         unsigned long flags;
 218
 219         if (!(mq->flags & MMC_QUEUE_SUSPENDED)) {
 220                 mq->flags |= MMC_QUEUE_SUSPENDED;
 221
 222                 spin_lock_irqsave(q->queue_lock, flags);
 223                 blk_stop_queue(q);
 224                 spin_unlock_irqrestore(q->queue_lock, flags);
 225
 226                 down(&mq->thread_sem);
 227         }
 228 }
 229 EXPORT_SYMBOL(mmc_queue_suspend);
 230
 231 /**
 232  * mmc_queue_resume - resume a previously suspended MMC request queue
 233  * @mq: MMC queue to resume
 234  */
 235 void mmc_queue_resume(struct mmc_queue *mq)
 236 {
 237         request_queue_t *q = mq->queue;
 238         unsigned long flags;
 239
 240         if (mq->flags & MMC_QUEUE_SUSPENDED) {
 241                 mq->flags &= ~MMC_QUEUE_SUSPENDED;
 242
 243                 up(&mq->thread_sem);
 244
 245                 spin_lock_irqsave(q->queue_lock, flags);
 246                 blk_start_queue(q);
 247                 spin_unlock_irqrestore(q->queue_lock, flags);
 248         }
 249 }
 250 EXPORT_SYMBOL(mmc_queue_resume);