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   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_BOUNCESZ      65536
  21
  22 #define MMC_QUEUE_SUSPENDED     (1 << 0)
  23
  24 /*
  25  * Prepare a MMC request. This just filters out odd stuff.
  26  */
  27 static int mmc_prep_request(struct request_queue *q, struct request *req)
  28 {
  29         /*
  30          * We only like normal block requests.
  31          */
  32         if (!blk_fs_request(req) && !blk_pc_request(req)) {
  33                 blk_dump_rq_flags(req, "MMC bad request");
  34                 return BLKPREP_KILL;
  35         }
  36
  37         req->cmd_flags |= REQ_DONTPREP;
  38
  39         return BLKPREP_OK;
  40 }
  41
  42 static int mmc_queue_thread(void *d)
  43 {
  44         struct mmc_queue *mq = d;
  45         struct request_queue *q = mq->queue;
  46
  47         /*
  48          * Set iothread to ensure that we aren't put to sleep by
  49          * the process freezing.  We handle suspension ourselves.
  50          */
  51         current->flags |= PF_MEMALLOC|PF_NOFREEZE;
  52
  53         down(&mq->thread_sem);
  54         do {
  55                 struct request *req = NULL;
  56
  57                 spin_lock_irq(q->queue_lock);
  58                 set_current_state(TASK_INTERRUPTIBLE);
  59                 if (!blk_queue_plugged(q))
  60                         req = elv_next_request(q);
  61                 mq->req = req;
  62                 spin_unlock_irq(q->queue_lock);
  63
  64                 if (!req) {
  65                         if (kthread_should_stop()) {
  66                                 set_current_state(TASK_RUNNING);
  67                                 break;
  68                         }
  69                         up(&mq->thread_sem);
  70                         schedule();
  71                         down(&mq->thread_sem);
  72                         continue;
  73                 }
  74                 set_current_state(TASK_RUNNING);
  75
  76                 mq->issue_fn(mq, req);
  77         } while (1);
  78         up(&mq->thread_sem);
  79
  80         return 0;
  81 }
  82
  83 /*
  84  * Generic MMC request handler.  This is called for any queue on a
  85  * particular host.  When the host is not busy, we look for a request
  86  * on any queue on this host, and attempt to issue it.  This may
  87  * not be the queue we were asked to process.
  88  */
  89 static void mmc_request(request_queue_t *q)
  90 {
  91         struct mmc_queue *mq = q->queuedata;
  92         struct request *req;
  93         int ret;
  94
  95         if (!mq) {
  96                 printk(KERN_ERR "MMC: killing requests for dead queue\n");
  97                 while ((req = elv_next_request(q)) != NULL) {
  98                         do {
  99                                 ret = end_that_request_chunk(req, 0,
 100                                         req->current_nr_sectors << 9);
 101                         } while (ret);
 102                 }
 103                 return;
 104         }
 105
 106         if (!mq->req)
 107                 wake_up_process(mq->thread);
 108 }
 109
 110 /**
 111  * mmc_init_queue - initialise a queue structure.
 112  * @mq: mmc queue
 113  * @card: mmc card to attach this queue
 114  * @lock: queue lock
 115  *
 116  * Initialise a MMC card request queue.
 117  */
 118 int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, spinlock_t *lock)
 119 {
 120         struct mmc_host *host = card->host;
 121         u64 limit = BLK_BOUNCE_HIGH;
 122         int ret;
 123         unsigned int bouncesz;
 124
 125         if (mmc_dev(host)->dma_mask && *mmc_dev(host)->dma_mask)
 126                 limit = *mmc_dev(host)->dma_mask;
 127
 128         mq->card = card;
 129         mq->queue = blk_init_queue(mmc_request, lock);
 130         if (!mq->queue)
 131                 return -ENOMEM;
 132
 133         mq->queue->queuedata = mq;
 134         mq->req = NULL;
 135
 136         blk_queue_prep_rq(mq->queue, mmc_prep_request);
 137
 138 #ifdef CONFIG_MMC_BLOCK_BOUNCE
 139         if (host->max_hw_segs == 1) {
 140                 bouncesz = MMC_QUEUE_BOUNCESZ;
 141
 142                 if (bouncesz > host->max_req_size)
 143                         bouncesz = host->max_req_size;
 144                 if (bouncesz > host->max_seg_size)
 145                         bouncesz = host->max_seg_size;
 146
 147                 mq->bounce_buf = kmalloc(bouncesz, GFP_KERNEL);
 148                 if (!mq->bounce_buf) {
 149                         printk(KERN_WARNING "%s: unable to allocate "
 150                                 "bounce buffer\n", mmc_card_name(card));
 151                 } else {
 152                         blk_queue_bounce_limit(mq->queue, BLK_BOUNCE_HIGH);
 153                         blk_queue_max_sectors(mq->queue, bouncesz / 512);
 154                         blk_queue_max_phys_segments(mq->queue, bouncesz / 512);
 155                         blk_queue_max_hw_segments(mq->queue, bouncesz / 512);
 156                         blk_queue_max_segment_size(mq->queue, bouncesz);
 157
 158                         mq->sg = kmalloc(sizeof(struct scatterlist),
 159                                 GFP_KERNEL);
 160                         if (!mq->sg) {
 161                                 ret = -ENOMEM;
 162                                 goto free_bounce_buf;
 163                         }
 164
 165                         mq->bounce_sg = kmalloc(sizeof(struct scatterlist) *
 166                                 bouncesz / 512, GFP_KERNEL);
 167                         if (!mq->bounce_sg) {
 168                                 ret = -ENOMEM;
 169                                 goto free_sg;
 170                         }
 171                 }
 172         }
 173 #endif
 174
 175         if (!mq->bounce_buf) {
 176                 blk_queue_bounce_limit(mq->queue, limit);
 177                 blk_queue_max_sectors(mq->queue, host->max_req_size / 512);
 178                 blk_queue_max_phys_segments(mq->queue, host->max_phys_segs);
 179                 blk_queue_max_hw_segments(mq->queue, host->max_hw_segs);
 180                 blk_queue_max_segment_size(mq->queue, host->max_seg_size);
 181
 182                 mq->sg = kmalloc(sizeof(struct scatterlist) *
 183                         host->max_phys_segs, GFP_KERNEL);
 184                 if (!mq->sg) {
 185                         ret = -ENOMEM;
 186                         goto cleanup_queue;
 187                 }
 188         }
 189
 190         init_MUTEX(&mq->thread_sem);
 191
 192         mq->thread = kthread_run(mmc_queue_thread, mq, "mmcqd");
 193         if (IS_ERR(mq->thread)) {
 194                 ret = PTR_ERR(mq->thread);
 195                 goto free_bounce_sg;
 196         }
 197
 198         return 0;
 199  free_bounce_sg:
 200         if (mq->bounce_sg)
 201                 kfree(mq->bounce_sg);
 202         mq->bounce_sg = NULL;
 203  free_sg:
 204         kfree(mq->sg);
 205         mq->sg = NULL;
 206  free_bounce_buf:
 207         if (mq->bounce_buf)
 208                 kfree(mq->bounce_buf);
 209         mq->bounce_buf = NULL;
 210  cleanup_queue:
 211         blk_cleanup_queue(mq->queue);
 212         return ret;
 213 }
 214
 215 void mmc_cleanup_queue(struct mmc_queue *mq)
 216 {
 217         request_queue_t *q = mq->queue;
 218         unsigned long flags;
 219
 220         /* Mark that we should start throwing out stragglers */
 221         spin_lock_irqsave(q->queue_lock, flags);
 222         q->queuedata = NULL;
 223         spin_unlock_irqrestore(q->queue_lock, flags);
 224
 225         /* Make sure the queue isn't suspended, as that will deadlock */
 226         mmc_queue_resume(mq);
 227
 228         /* Then terminate our worker thread */
 229         kthread_stop(mq->thread);
 230
 231         if (mq->bounce_sg)
 232                 kfree(mq->bounce_sg);
 233         mq->bounce_sg = NULL;
 234
 235         kfree(mq->sg);
 236         mq->sg = NULL;
 237
 238         if (mq->bounce_buf)
 239                 kfree(mq->bounce_buf);
 240         mq->bounce_buf = NULL;
 241
 242         blk_cleanup_queue(mq->queue);
 243
 244         mq->card = NULL;
 245 }
 246 EXPORT_SYMBOL(mmc_cleanup_queue);
 247
 248 /**
 249  * mmc_queue_suspend - suspend a MMC request queue
 250  * @mq: MMC queue to suspend
 251  *
 252  * Stop the block request queue, and wait for our thread to
 253  * complete any outstanding requests.  This ensures that we
 254  * won't suspend while a request is being processed.
 255  */
 256 void mmc_queue_suspend(struct mmc_queue *mq)
 257 {
 258         request_queue_t *q = mq->queue;
 259         unsigned long flags;
 260
 261         if (!(mq->flags & MMC_QUEUE_SUSPENDED)) {
 262                 mq->flags |= MMC_QUEUE_SUSPENDED;
 263
 264                 spin_lock_irqsave(q->queue_lock, flags);
 265                 blk_stop_queue(q);
 266                 spin_unlock_irqrestore(q->queue_lock, flags);
 267
 268                 down(&mq->thread_sem);
 269         }
 270 }
 271
 272 /**
 273  * mmc_queue_resume - resume a previously suspended MMC request queue
 274  * @mq: MMC queue to resume
 275  */
 276 void mmc_queue_resume(struct mmc_queue *mq)
 277 {
 278         request_queue_t *q = mq->queue;
 279         unsigned long flags;
 280
 281         if (mq->flags & MMC_QUEUE_SUSPENDED) {
 282                 mq->flags &= ~MMC_QUEUE_SUSPENDED;
 283
 284                 up(&mq->thread_sem);
 285
 286                 spin_lock_irqsave(q->queue_lock, flags);
 287                 blk_start_queue(q);
 288                 spin_unlock_irqrestore(q->queue_lock, flags);
 289         }
 290 }
 291
 292 static void copy_sg(struct scatterlist *dst, unsigned int dst_len,
 293         struct scatterlist *src, unsigned int src_len)
 294 {
 295         unsigned int chunk;
 296         char *dst_buf, *src_buf;
 297         unsigned int dst_size, src_size;
 298
 299         dst_buf = NULL;
 300         src_buf = NULL;
 301         dst_size = 0;
 302         src_size = 0;
 303
 304         while (src_len) {
 305                 BUG_ON(dst_len == 0);
 306
 307                 if (dst_size == 0) {
 308                         dst_buf = page_address(dst->page) + dst->offset;
 309                         dst_size = dst->length;
 310                 }
 311
 312                 if (src_size == 0) {
 313                         src_buf = page_address(src->page) + src->offset;
 314                         src_size = src->length;
 315                 }
 316
 317                 chunk = min(dst_size, src_size);
 318
 319                 memcpy(dst_buf, src_buf, chunk);
 320
 321                 dst_buf += chunk;
 322                 src_buf += chunk;
 323                 dst_size -= chunk;
 324                 src_size -= chunk;
 325
 326                 if (dst_size == 0) {
 327                         dst++;
 328                         dst_len--;
 329                 }
 330
 331                 if (src_size == 0) {
 332                         src++;
 333                         src_len--;
 334                 }
 335         }
 336 }
 337
 338 unsigned int mmc_queue_map_sg(struct mmc_queue *mq)
 339 {
 340         unsigned int sg_len;
 341
 342         if (!mq->bounce_buf)
 343                 return blk_rq_map_sg(mq->queue, mq->req, mq->sg);
 344
 345         BUG_ON(!mq->bounce_sg);
 346
 347         sg_len = blk_rq_map_sg(mq->queue, mq->req, mq->bounce_sg);
 348
 349         mq->bounce_sg_len = sg_len;
 350
 351         /*
 352          * Shortcut in the event we only get a single entry.
 353          */
 354         if (sg_len == 1) {
 355                 memcpy(mq->sg, mq->bounce_sg, sizeof(struct scatterlist));
 356                 return 1;
 357         }
 358
 359         mq->sg[0].page = virt_to_page(mq->bounce_buf);
 360         mq->sg[0].offset = offset_in_page(mq->bounce_buf);
 361         mq->sg[0].length = 0;
 362
 363         while (sg_len) {
 364                 mq->sg[0].length += mq->bounce_sg[sg_len - 1].length;
 365                 sg_len--;
 366         }
 367
 368         return 1;
 369 }
 370
 371 void mmc_queue_bounce_pre(struct mmc_queue *mq)
 372 {
 373         if (!mq->bounce_buf)
 374                 return;
 375
 376         if (mq->bounce_sg_len == 1)
 377                 return;
 378         if (rq_data_dir(mq->req) != WRITE)
 379                 return;
 380
 381         copy_sg(mq->sg, 1, mq->bounce_sg, mq->bounce_sg_len);
 382 }
 383
 384 void mmc_queue_bounce_post(struct mmc_queue *mq)
 385 {
 386         if (!mq->bounce_buf)
 387                 return;
 388
 389         if (mq->bounce_sg_len == 1)
 390                 return;
 391         if (rq_data_dir(mq->req) != READ)
 392                 return;
 393
 394         copy_sg(mq->bounce_sg, mq->bounce_sg_len, mq->sg, 1);
 395 }
 396