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