drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c

   1 /**
   2  * Copyright (c) 2010-2012 Broadcom. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions, and the following disclaimer,
   9  *    without modification.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. The names of the above-listed copyright holders may not be used
  14  *    to endorse or promote products derived from this software without
  15  *    specific prior written permission.
  16  *
  17  * ALTERNATIVELY, this software may be distributed under the terms of the
  18  * GNU General Public License ("GPL") version 2, as published by the Free
  19  * Software Foundation.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  22  * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  23  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  24  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  25  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  26  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  27  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  28  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  29  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  30  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  31  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #include <linux/kernel.h>
  35 #include <linux/types.h>
  36 #include <linux/errno.h>
  37 #include <linux/interrupt.h>
  38 #include <linux/pagemap.h>
  39 #include <linux/dma-mapping.h>
  40 #include <linux/io.h>
  41 #include <linux/platform_device.h>
  42 #include <linux/uaccess.h>
  43 #include <linux/mm.h>
  44 #include <linux/of.h>
  45 #include <soc/bcm2835/raspberrypi-firmware.h>
  46
  47 #define TOTAL_SLOTS (VCHIQ_SLOT_ZERO_SLOTS + 2 * 32)
  48
  49 #include "vchiq_arm.h"
  50 #include "vchiq_connected.h"
  51 #include "vchiq_killable.h"
  52 #include "vchiq_pagelist.h"
  53
  54 #define MAX_FRAGMENTS (VCHIQ_NUM_CURRENT_BULKS * 2)
  55
  56 #define VCHIQ_PLATFORM_FRAGMENTS_OFFSET_IDX 0
  57 #define VCHIQ_PLATFORM_FRAGMENTS_COUNT_IDX  1
  58
  59 #define BELL0   0x00
  60 #define BELL2   0x08
  61
  62 struct vchiq_2835_state {
  63         int inited;
  64         VCHIQ_ARM_STATE_T arm_state;
  65 };
  66
  67 struct vchiq_pagelist_info {
  68         PAGELIST_T *pagelist;
  69         size_t pagelist_buffer_size;
  70         dma_addr_t dma_addr;
  71         enum dma_data_direction dma_dir;
  72         unsigned int num_pages;
  73         unsigned int pages_need_release;
  74         struct page **pages;
  75         struct scatterlist *scatterlist;
  76         unsigned int scatterlist_mapped;
  77 };
  78
  79 static void __iomem *g_regs;
  80 /* This value is the size of the L2 cache lines as understood by the
  81  * VPU firmware, which determines the required alignment of the
  82  * offsets/sizes in pagelists.
  83  *
  84  * Modern VPU firmware looks for a DT "cache-line-size" property in
  85  * the VCHIQ node and will overwrite it with the actual L2 cache size,
  86  * which the kernel must then respect.  That property was rejected
  87  * upstream, so we have to use the VPU firmware's compatibility value
  88  * of 32.
  89  */
  90 static unsigned int g_cache_line_size = 32;
  91 static unsigned int g_fragments_size;
  92 static char *g_fragments_base;
  93 static char *g_free_fragments;
  94 static struct semaphore g_free_fragments_sema;
  95 static struct device *g_dev;
  96
  97 static DEFINE_SEMAPHORE(g_free_fragments_mutex);
  98
  99 static irqreturn_t
 100 vchiq_doorbell_irq(int irq, void *dev_id);
 101
 102 static struct vchiq_pagelist_info *
 103 create_pagelist(char __user *buf, size_t count, unsigned short type);
 104
 105 static void
 106 free_pagelist(struct vchiq_pagelist_info *pagelistinfo,
 107               int actual);
 108
 109 int vchiq_platform_init(struct platform_device *pdev, VCHIQ_STATE_T *state)
 110 {
 111         struct device *dev = &pdev->dev;
 112         struct rpi_firmware *fw = platform_get_drvdata(pdev);
 113         VCHIQ_SLOT_ZERO_T *vchiq_slot_zero;
 114         struct resource *res;
 115         void *slot_mem;
 116         dma_addr_t slot_phys;
 117         u32 channelbase;
 118         int slot_mem_size, frag_mem_size;
 119         int err, irq, i;
 120
 121         /*
 122          * VCHI messages between the CPU and firmware use
 123          * 32-bit bus addresses.
 124          */
 125         err = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
 126
 127         if (err < 0)
 128                 return err;
 129
 130         g_fragments_size = 2 * g_cache_line_size;
 131
 132         /* Allocate space for the channels in coherent memory */
 133         slot_mem_size = PAGE_ALIGN(TOTAL_SLOTS * VCHIQ_SLOT_SIZE);
 134         frag_mem_size = PAGE_ALIGN(g_fragments_size * MAX_FRAGMENTS);
 135
 136         slot_mem = dmam_alloc_coherent(dev, slot_mem_size + frag_mem_size,
 137                                        &slot_phys, GFP_KERNEL);
 138         if (!slot_mem) {
 139                 dev_err(dev, "could not allocate DMA memory\n");
 140                 return -ENOMEM;
 141         }
 142
 143         WARN_ON(((unsigned long)slot_mem & (PAGE_SIZE - 1)) != 0);
 144
 145         vchiq_slot_zero = vchiq_init_slots(slot_mem, slot_mem_size);
 146         if (!vchiq_slot_zero)
 147                 return -EINVAL;
 148
 149         vchiq_slot_zero->platform_data[VCHIQ_PLATFORM_FRAGMENTS_OFFSET_IDX] =
 150                 (int)slot_phys + slot_mem_size;
 151         vchiq_slot_zero->platform_data[VCHIQ_PLATFORM_FRAGMENTS_COUNT_IDX] =
 152                 MAX_FRAGMENTS;
 153
 154         g_fragments_base = (char *)slot_mem + slot_mem_size;
 155
 156         g_free_fragments = g_fragments_base;
 157         for (i = 0; i < (MAX_FRAGMENTS - 1); i++) {
 158                 *(char **)&g_fragments_base[i*g_fragments_size] =
 159                         &g_fragments_base[(i + 1)*g_fragments_size];
 160         }
 161         *(char **)&g_fragments_base[i * g_fragments_size] = NULL;
 162         sema_init(&g_free_fragments_sema, MAX_FRAGMENTS);
 163
 164         if (vchiq_init_state(state, vchiq_slot_zero, 0) != VCHIQ_SUCCESS)
 165                 return -EINVAL;
 166
 167         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 168         g_regs = devm_ioremap_resource(&pdev->dev, res);
 169         if (IS_ERR(g_regs))
 170                 return PTR_ERR(g_regs);
 171
 172         irq = platform_get_irq(pdev, 0);
 173         if (irq <= 0) {
 174                 dev_err(dev, "failed to get IRQ\n");
 175                 return irq;
 176         }
 177
 178         err = devm_request_irq(dev, irq, vchiq_doorbell_irq, IRQF_IRQPOLL,
 179                                "VCHIQ doorbell", state);
 180         if (err) {
 181                 dev_err(dev, "failed to register irq=%d\n", irq);
 182                 return err;
 183         }
 184
 185         /* Send the base address of the slots to VideoCore */
 186         channelbase = slot_phys;
 187         err = rpi_firmware_property(fw, RPI_FIRMWARE_VCHIQ_INIT,
 188                                     &channelbase, sizeof(channelbase));
 189         if (err || channelbase) {
 190                 dev_err(dev, "failed to set channelbase\n");
 191                 return err ? : -ENXIO;
 192         }
 193
 194         g_dev = dev;
 195         vchiq_log_info(vchiq_arm_log_level,
 196                 "vchiq_init - done (slots %pK, phys %pad)",
 197                 vchiq_slot_zero, &slot_phys);
 198
 199         vchiq_call_connected_callbacks();
 200
 201         return 0;
 202 }
 203
 204 VCHIQ_STATUS_T
 205 vchiq_platform_init_state(VCHIQ_STATE_T *state)
 206 {
 207         VCHIQ_STATUS_T status = VCHIQ_SUCCESS;
 208         struct vchiq_2835_state *platform_state;
 209
 210         state->platform_state = kzalloc(sizeof(*platform_state), GFP_KERNEL);
 211         if (!state->platform_state)
 212                 return VCHIQ_ERROR;
 213
 214         platform_state = (struct vchiq_2835_state *)state->platform_state;
 215
 216         platform_state->inited = 1;
 217         status = vchiq_arm_init_state(state, &platform_state->arm_state);
 218
 219         if (status != VCHIQ_SUCCESS)
 220                 platform_state->inited = 0;
 221
 222         return status;
 223 }
 224
 225 VCHIQ_ARM_STATE_T*
 226 vchiq_platform_get_arm_state(VCHIQ_STATE_T *state)
 227 {
 228         struct vchiq_2835_state *platform_state;
 229
 230         platform_state   = (struct vchiq_2835_state *)state->platform_state;
 231
 232         WARN_ON_ONCE(!platform_state->inited);
 233
 234         return &platform_state->arm_state;
 235 }
 236
 237 void
 238 remote_event_signal(REMOTE_EVENT_T *event)
 239 {
 240         wmb();
 241
 242         event->fired = 1;
 243
 244         dsb(sy);         /* data barrier operation */
 245
 246         if (event->armed)
 247                 writel(0, g_regs + BELL2); /* trigger vc interrupt */
 248 }
 249
 250 VCHIQ_STATUS_T
 251 vchiq_prepare_bulk_data(VCHIQ_BULK_T *bulk, VCHI_MEM_HANDLE_T memhandle,
 252         void *offset, int size, int dir)
 253 {
 254         struct vchiq_pagelist_info *pagelistinfo;
 255
 256         WARN_ON(memhandle != VCHI_MEM_HANDLE_INVALID);
 257
 258         pagelistinfo = create_pagelist((char __user *)offset, size,
 259                                        (dir == VCHIQ_BULK_RECEIVE)
 260                                        ? PAGELIST_READ
 261                                        : PAGELIST_WRITE);
 262
 263         if (!pagelistinfo)
 264                 return VCHIQ_ERROR;
 265
 266         bulk->handle = memhandle;
 267         bulk->data = (void *)(unsigned long)pagelistinfo->dma_addr;
 268
 269         /*
 270          * Store the pagelistinfo address in remote_data,
 271          * which isn't used by the slave.
 272          */
 273         bulk->remote_data = pagelistinfo;
 274
 275         return VCHIQ_SUCCESS;
 276 }
 277
 278 void
 279 vchiq_complete_bulk(VCHIQ_BULK_T *bulk)
 280 {
 281         if (bulk && bulk->remote_data && bulk->actual)
 282                 free_pagelist((struct vchiq_pagelist_info *)bulk->remote_data,
 283                               bulk->actual);
 284 }
 285
 286 void
 287 vchiq_transfer_bulk(VCHIQ_BULK_T *bulk)
 288 {
 289         /*
 290          * This should only be called on the master (VideoCore) side, but
 291          * provide an implementation to avoid the need for ifdefery.
 292          */
 293         BUG();
 294 }
 295
 296 void
 297 vchiq_dump_platform_state(void *dump_context)
 298 {
 299         char buf[80];
 300         int len;
 301
 302         len = snprintf(buf, sizeof(buf),
 303                 "  Platform: 2835 (VC master)");
 304         vchiq_dump(dump_context, buf, len + 1);
 305 }
 306
 307 VCHIQ_STATUS_T
 308 vchiq_platform_suspend(VCHIQ_STATE_T *state)
 309 {
 310         return VCHIQ_ERROR;
 311 }
 312
 313 VCHIQ_STATUS_T
 314 vchiq_platform_resume(VCHIQ_STATE_T *state)
 315 {
 316         return VCHIQ_SUCCESS;
 317 }
 318
 319 void
 320 vchiq_platform_paused(VCHIQ_STATE_T *state)
 321 {
 322 }
 323
 324 void
 325 vchiq_platform_resumed(VCHIQ_STATE_T *state)
 326 {
 327 }
 328
 329 int
 330 vchiq_platform_videocore_wanted(VCHIQ_STATE_T *state)
 331 {
 332         return 1; // autosuspend not supported - videocore always wanted
 333 }
 334
 335 int
 336 vchiq_platform_use_suspend_timer(void)
 337 {
 338         return 0;
 339 }
 340 void
 341 vchiq_dump_platform_use_state(VCHIQ_STATE_T *state)
 342 {
 343         vchiq_log_info(vchiq_arm_log_level, "Suspend timer not in use");
 344 }
 345 void
 346 vchiq_platform_handle_timeout(VCHIQ_STATE_T *state)
 347 {
 348         (void)state;
 349 }
 350 /*
 351  * Local functions
 352  */
 353
 354 static irqreturn_t
 355 vchiq_doorbell_irq(int irq, void *dev_id)
 356 {
 357         VCHIQ_STATE_T *state = dev_id;
 358         irqreturn_t ret = IRQ_NONE;
 359         unsigned int status;
 360
 361         /* Read (and clear) the doorbell */
 362         status = readl(g_regs + BELL0);
 363
 364         if (status & 0x4) {  /* Was the doorbell rung? */
 365                 remote_event_pollall(state);
 366                 ret = IRQ_HANDLED;
 367         }
 368
 369         return ret;
 370 }
 371
 372 static void
 373 cleanup_pagelistinfo(struct vchiq_pagelist_info *pagelistinfo)
 374 {
 375         if (pagelistinfo->scatterlist_mapped) {
 376                 dma_unmap_sg(g_dev, pagelistinfo->scatterlist,
 377                              pagelistinfo->num_pages, pagelistinfo->dma_dir);
 378         }
 379
 380         if (pagelistinfo->pages_need_release) {
 381                 unsigned int i;
 382
 383                 for (i = 0; i < pagelistinfo->num_pages; i++)
 384                         put_page(pagelistinfo->pages[i]);
 385         }
 386
 387         dma_free_coherent(g_dev, pagelistinfo->pagelist_buffer_size,
 388                           pagelistinfo->pagelist, pagelistinfo->dma_addr);
 389 }
 390
 391 /* There is a potential problem with partial cache lines (pages?)
 392  * at the ends of the block when reading. If the CPU accessed anything in
 393  * the same line (page?) then it may have pulled old data into the cache,
 394  * obscuring the new data underneath. We can solve this by transferring the
 395  * partial cache lines separately, and allowing the ARM to copy into the
 396  * cached area.
 397  */
 398
 399 static struct vchiq_pagelist_info *
 400 create_pagelist(char __user *buf, size_t count, unsigned short type)
 401 {
 402         PAGELIST_T *pagelist;
 403         struct vchiq_pagelist_info *pagelistinfo;
 404         struct page **pages;
 405         u32 *addrs;
 406         unsigned int num_pages, offset, i, k;
 407         int actual_pages;
 408         size_t pagelist_size;
 409         struct scatterlist *scatterlist, *sg;
 410         int dma_buffers;
 411         dma_addr_t dma_addr;
 412
 413         if (count >= INT_MAX - PAGE_SIZE)
 414                 return NULL;
 415
 416         offset = ((unsigned int)(unsigned long)buf & (PAGE_SIZE - 1));
 417         num_pages = DIV_ROUND_UP(count + offset, PAGE_SIZE);
 418
 419         if (num_pages > (SIZE_MAX - sizeof(PAGELIST_T) -
 420                          sizeof(struct vchiq_pagelist_info)) /
 421                         (sizeof(u32) + sizeof(pages[0]) +
 422                          sizeof(struct scatterlist)))
 423                 return NULL;
 424
 425         pagelist_size = sizeof(PAGELIST_T) +
 426                         (num_pages * sizeof(u32)) +
 427                         (num_pages * sizeof(pages[0]) +
 428                         (num_pages * sizeof(struct scatterlist))) +
 429                         sizeof(struct vchiq_pagelist_info);
 430
 431         /* Allocate enough storage to hold the page pointers and the page
 432          * list
 433          */
 434         pagelist = dma_zalloc_coherent(g_dev,
 435                                        pagelist_size,
 436                                        &dma_addr,
 437                                        GFP_KERNEL);
 438
 439         vchiq_log_trace(vchiq_arm_log_level, "%s - %pK", __func__, pagelist);
 440
 441         if (!pagelist)
 442                 return NULL;
 443
 444         addrs           = pagelist->addrs;
 445         pages           = (struct page **)(addrs + num_pages);
 446         scatterlist     = (struct scatterlist *)(pages + num_pages);
 447         pagelistinfo    = (struct vchiq_pagelist_info *)
 448                           (scatterlist + num_pages);
 449
 450         pagelist->length = count;
 451         pagelist->type = type;
 452         pagelist->offset = offset;
 453
 454         /* Populate the fields of the pagelistinfo structure */
 455         pagelistinfo->pagelist = pagelist;
 456         pagelistinfo->pagelist_buffer_size = pagelist_size;
 457         pagelistinfo->dma_addr = dma_addr;
 458         pagelistinfo->dma_dir =  (type == PAGELIST_WRITE) ?
 459                                   DMA_TO_DEVICE : DMA_FROM_DEVICE;
 460         pagelistinfo->num_pages = num_pages;
 461         pagelistinfo->pages_need_release = 0;
 462         pagelistinfo->pages = pages;
 463         pagelistinfo->scatterlist = scatterlist;
 464         pagelistinfo->scatterlist_mapped = 0;
 465
 466         if (is_vmalloc_addr(buf)) {
 467                 unsigned long length = count;
 468                 unsigned int off = offset;
 469
 470                 for (actual_pages = 0; actual_pages < num_pages;
 471                      actual_pages++) {
 472                         struct page *pg = vmalloc_to_page(buf + (actual_pages *
 473                                                                  PAGE_SIZE));
 474                         size_t bytes = PAGE_SIZE - off;
 475
 476                         if (!pg) {
 477                                 cleanup_pagelistinfo(pagelistinfo);
 478                                 return NULL;
 479                         }
 480
 481                         if (bytes > length)
 482                                 bytes = length;
 483                         pages[actual_pages] = pg;
 484                         length -= bytes;
 485                         off = 0;
 486                 }
 487                 /* do not try and release vmalloc pages */
 488         } else {
 489                 actual_pages = get_user_pages_fast(
 490                                           (unsigned long)buf & PAGE_MASK,
 491                                           num_pages,
 492                                           type == PAGELIST_READ,
 493                                           pages);
 494
 495                 if (actual_pages != num_pages) {
 496                         vchiq_log_info(vchiq_arm_log_level,
 497                                        "%s - only %d/%d pages locked",
 498                                        __func__, actual_pages, num_pages);
 499
 500                         /* This is probably due to the process being killed */
 501                         while (actual_pages > 0) {
 502                                 actual_pages--;
 503                                 put_page(pages[actual_pages]);
 504                         }
 505                         cleanup_pagelistinfo(pagelistinfo);
 506                         return NULL;
 507                 }
 508                  /* release user pages */
 509                 pagelistinfo->pages_need_release = 1;
 510         }
 511
 512         /*
 513          * Initialize the scatterlist so that the magic cookie
 514          *  is filled if debugging is enabled
 515          */
 516         sg_init_table(scatterlist, num_pages);
 517         /* Now set the pages for each scatterlist */
 518         for (i = 0; i < num_pages; i++) {
 519                 unsigned int len = PAGE_SIZE - offset;
 520
 521                 if (len > count)
 522                         len = count;
 523                 sg_set_page(scatterlist + i, pages[i], len, offset);
 524                 offset = 0;
 525                 count -= len;
 526         }
 527
 528         dma_buffers = dma_map_sg(g_dev,
 529                                  scatterlist,
 530                                  num_pages,
 531                                  pagelistinfo->dma_dir);
 532
 533         if (dma_buffers == 0) {
 534                 cleanup_pagelistinfo(pagelistinfo);
 535                 return NULL;
 536         }
 537
 538         pagelistinfo->scatterlist_mapped = 1;
 539
 540         /* Combine adjacent blocks for performance */
 541         k = 0;
 542         for_each_sg(scatterlist, sg, dma_buffers, i) {
 543                 u32 len = sg_dma_len(sg);
 544                 u32 addr = sg_dma_address(sg);
 545
 546                 /* Note: addrs is the address + page_count - 1
 547                  * The firmware expects blocks after the first to be page-
 548                  * aligned and a multiple of the page size
 549                  */
 550                 WARN_ON(len == 0);
 551                 WARN_ON(i && (i != (dma_buffers - 1)) && (len & ~PAGE_MASK));
 552                 WARN_ON(i && (addr & ~PAGE_MASK));
 553                 if (k > 0 &&
 554                     ((addrs[k - 1] & PAGE_MASK) +
 555                      (((addrs[k - 1] & ~PAGE_MASK) + 1) << PAGE_SHIFT))
 556                     == (addr & PAGE_MASK))
 557                         addrs[k - 1] += ((len + PAGE_SIZE - 1) >> PAGE_SHIFT);
 558                 else
 559                         addrs[k++] = (addr & PAGE_MASK) |
 560                                 (((len + PAGE_SIZE - 1) >> PAGE_SHIFT) - 1);
 561         }
 562
 563         /* Partial cache lines (fragments) require special measures */
 564         if ((type == PAGELIST_READ) &&
 565                 ((pagelist->offset & (g_cache_line_size - 1)) ||
 566                 ((pagelist->offset + pagelist->length) &
 567                 (g_cache_line_size - 1)))) {
 568                 char *fragments;
 569
 570                 if (down_interruptible(&g_free_fragments_sema) != 0) {
 571                         cleanup_pagelistinfo(pagelistinfo);
 572                         return NULL;
 573                 }
 574
 575                 WARN_ON(g_free_fragments == NULL);
 576
 577                 down(&g_free_fragments_mutex);
 578                 fragments = g_free_fragments;
 579                 WARN_ON(fragments == NULL);
 580                 g_free_fragments = *(char **) g_free_fragments;
 581                 up(&g_free_fragments_mutex);
 582                 pagelist->type = PAGELIST_READ_WITH_FRAGMENTS +
 583                         (fragments - g_fragments_base) / g_fragments_size;
 584         }
 585
 586         return pagelistinfo;
 587 }
 588
 589 static void
 590 free_pagelist(struct vchiq_pagelist_info *pagelistinfo,
 591               int actual)
 592 {
 593         PAGELIST_T *pagelist   = pagelistinfo->pagelist;
 594         struct page **pages    = pagelistinfo->pages;
 595         unsigned int num_pages = pagelistinfo->num_pages;
 596
 597         vchiq_log_trace(vchiq_arm_log_level, "%s - %pK, %d",
 598                         __func__, pagelistinfo->pagelist, actual);
 599
 600         /*
 601          * NOTE: dma_unmap_sg must be called before the
 602          * cpu can touch any of the data/pages.
 603          */
 604         dma_unmap_sg(g_dev, pagelistinfo->scatterlist,
 605                      pagelistinfo->num_pages, pagelistinfo->dma_dir);
 606         pagelistinfo->scatterlist_mapped = 0;
 607
 608         /* Deal with any partial cache lines (fragments) */
 609         if (pagelist->type >= PAGELIST_READ_WITH_FRAGMENTS) {
 610                 char *fragments = g_fragments_base +
 611                         (pagelist->type - PAGELIST_READ_WITH_FRAGMENTS) *
 612                         g_fragments_size;
 613                 int head_bytes, tail_bytes;
 614
 615                 head_bytes = (g_cache_line_size - pagelist->offset) &
 616                         (g_cache_line_size - 1);
 617                 tail_bytes = (pagelist->offset + actual) &
 618                         (g_cache_line_size - 1);
 619
 620                 if ((actual >= 0) && (head_bytes != 0)) {
 621                         if (head_bytes > actual)
 622                                 head_bytes = actual;
 623
 624                         memcpy((char *)kmap(pages[0]) +
 625                                 pagelist->offset,
 626                                 fragments,
 627                                 head_bytes);
 628                         kunmap(pages[0]);
 629                 }
 630                 if ((actual >= 0) && (head_bytes < actual) &&
 631                         (tail_bytes != 0)) {
 632                         memcpy((char *)kmap(pages[num_pages - 1]) +
 633                                 ((pagelist->offset + actual) &
 634                                 (PAGE_SIZE - 1) & ~(g_cache_line_size - 1)),
 635                                 fragments + g_cache_line_size,
 636                                 tail_bytes);
 637                         kunmap(pages[num_pages - 1]);
 638                 }
 639
 640                 down(&g_free_fragments_mutex);
 641                 *(char **)fragments = g_free_fragments;
 642                 g_free_fragments = fragments;
 643                 up(&g_free_fragments_mutex);
 644                 up(&g_free_fragments_sema);
 645         }
 646
 647         /* Need to mark all the pages dirty. */
 648         if (pagelist->type != PAGELIST_WRITE &&
 649             pagelistinfo->pages_need_release) {
 650                 unsigned int i;
 651
 652                 for (i = 0; i < num_pages; i++)
 653                         set_page_dirty(pages[i]);
 654         }
 655
 656         cleanup_pagelistinfo(pagelistinfo);
 657 }