Free Electrons

Embedded Linux Experts

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
/*
 * ispqueue.c
 *
 * TI OMAP3 ISP - Video buffers queue handling
 *
 * Copyright (C) 2010 Nokia Corporation
 *
 * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
 *	     Sakari Ailus <sakari.ailus@iki.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <asm/cacheflush.h>
#include <linux/dma-mapping.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/poll.h>
#include <linux/scatterlist.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

#include "ispqueue.h"

/* -----------------------------------------------------------------------------
 * Video buffers management
 */

/*
 * isp_video_buffer_cache_sync - Keep the buffers coherent between CPU and ISP
 *
 * The typical operation required here is Cache Invalidation across
 * the (user space) buffer address range. And this _must_ be done
 * at QBUF stage (and *only* at QBUF).
 *
 * We try to use optimal cache invalidation function:
 * - dmac_map_area:
 *    - used when the number of pages are _low_.
 *    - it becomes quite slow as the number of pages increase.
 *       - for 648x492 viewfinder (150 pages) it takes 1.3 ms.
 *       - for 5 Mpix buffer (2491 pages) it takes between 25-50 ms.
 *
 * - flush_cache_all:
 *    - used when the number of pages are _high_.
 *    - time taken in the range of 500-900 us.
 *    - has a higher penalty but, as whole dcache + icache is invalidated
 */
/*
 * FIXME: dmac_inv_range crashes randomly on the user space buffer
 *        address. Fall back to flush_cache_all for now.
 */
#define ISP_CACHE_FLUSH_PAGES_MAX       0

static void isp_video_buffer_cache_sync(struct isp_video_buffer *buf)
{
	if (buf->skip_cache)
		return;

	if (buf->vbuf.m.userptr == 0 || buf->npages == 0 ||
	    buf->npages > ISP_CACHE_FLUSH_PAGES_MAX)
		flush_cache_all();
	else {
		dmac_map_area((void *)buf->vbuf.m.userptr, buf->vbuf.length,
			      DMA_FROM_DEVICE);
		outer_inv_range(buf->vbuf.m.userptr,
				buf->vbuf.m.userptr + buf->vbuf.length);
	}
}

/*
 * isp_video_buffer_lock_vma - Prevent VMAs from being unmapped
 *
 * Lock the VMAs underlying the given buffer into memory. This avoids the
 * userspace buffer mapping from being swapped out, making VIPT cache handling
 * easier.
 *
 * Note that the pages will not be freed as the buffers have been locked to
 * memory using by a call to get_user_pages(), but the userspace mapping could
 * still disappear if the VMAs are not locked. This is caused by the memory
 * management code trying to be as lock-less as possible, which results in the
 * userspace mapping manager not finding out that the pages are locked under
 * some conditions.
 */
static int isp_video_buffer_lock_vma(struct isp_video_buffer *buf, int lock)
{
	struct vm_area_struct *vma;
	unsigned long start;
	unsigned long end;
	int ret = 0;

	if (buf->vbuf.memory == V4L2_MEMORY_MMAP)
		return 0;

	/* We can be called from workqueue context if the current task dies to
	 * unlock the VMAs. In that case there's no current memory management
	 * context so unlocking can't be performed, but the VMAs have been or
	 * are getting destroyed anyway so it doesn't really matter.
	 */
	if (!current || !current->mm)
		return lock ? -EINVAL : 0;

	start = buf->vbuf.m.userptr;
	end = buf->vbuf.m.userptr + buf->vbuf.length - 1;

	down_write(&current->mm->mmap_sem);
	spin_lock(&current->mm->page_table_lock);

	do {
		vma = find_vma(current->mm, start);
		if (vma == NULL) {
			ret = -EFAULT;
			goto out;
		}

		if (lock)
			vma->vm_flags |= VM_LOCKED;
		else
			vma->vm_flags &= ~VM_LOCKED;

		start = vma->vm_end + 1;
	} while (vma->vm_end < end);

	if (lock)
		buf->vm_flags |= VM_LOCKED;
	else
		buf->vm_flags &= ~VM_LOCKED;

out:
	spin_unlock(&current->mm->page_table_lock);
	up_write(&current->mm->mmap_sem);
	return ret;
}

/*
 * isp_video_buffer_sglist_kernel - Build a scatter list for a vmalloc'ed buffer
 *
 * Iterate over the vmalloc'ed area and create a scatter list entry for every
 * page.
 */
static int isp_video_buffer_sglist_kernel(struct isp_video_buffer *buf)
{
	struct scatterlist *sglist;
	unsigned int npages;
	unsigned int i;
	void *addr;

	addr = buf->vaddr;
	npages = PAGE_ALIGN(buf->vbuf.length) >> PAGE_SHIFT;

	sglist = vmalloc(npages * sizeof(*sglist));
	if (sglist == NULL)
		return -ENOMEM;

	sg_init_table(sglist, npages);

	for (i = 0; i < npages; ++i, addr += PAGE_SIZE) {
		struct page *page = vmalloc_to_page(addr);

		if (page == NULL || PageHighMem(page)) {
			vfree(sglist);
			return -EINVAL;
		}

		sg_set_page(&sglist[i], page, PAGE_SIZE, 0);
	}

	buf->sglen = npages;
	buf->sglist = sglist;

	return 0;
}

/*
 * isp_video_buffer_sglist_user - Build a scatter list for a userspace buffer
 *
 * Walk the buffer pages list and create a 1:1 mapping to a scatter list.
 */
static int isp_video_buffer_sglist_user(struct isp_video_buffer *buf)
{
	struct scatterlist *sglist;
	unsigned int offset = buf->offset;
	unsigned int i;

	sglist = vmalloc(buf->npages * sizeof(*sglist));
	if (sglist == NULL)
		return -ENOMEM;

	sg_init_table(sglist, buf->npages);

	for (i = 0; i < buf->npages; ++i) {
		if (PageHighMem(buf->pages[i])) {
			vfree(sglist);
			return -EINVAL;
		}

		sg_set_page(&sglist[i], buf->pages[i], PAGE_SIZE - offset,
			    offset);
		offset = 0;
	}

	buf->sglen = buf->npages;
	buf->sglist = sglist;

	return 0;
}

/*
 * isp_video_buffer_sglist_pfnmap - Build a scatter list for a VM_PFNMAP buffer
 *
 * Create a scatter list of physically contiguous pages starting at the buffer
 * memory physical address.
 */
static int isp_video_buffer_sglist_pfnmap(struct isp_video_buffer *buf)
{
	struct scatterlist *sglist;
	unsigned int offset = buf->offset;
	unsigned long pfn = buf->paddr >> PAGE_SHIFT;
	unsigned int i;

	sglist = vmalloc(buf->npages * sizeof(*sglist));
	if (sglist == NULL)
		return -ENOMEM;

	sg_init_table(sglist, buf->npages);

	for (i = 0; i < buf->npages; ++i, ++pfn) {
		sg_set_page(&sglist[i], pfn_to_page(pfn), PAGE_SIZE - offset,
			    offset);
		/* PFNMAP buffers will not get DMA-mapped, set the DMA address
		 * manually.
		 */
		sg_dma_address(&sglist[i]) = (pfn << PAGE_SHIFT) + offset;
		offset = 0;
	}

	buf->sglen = buf->npages;
	buf->sglist = sglist;

	return 0;
}

/*
 * isp_video_buffer_cleanup - Release pages for a userspace VMA.
 *
 * Release pages locked by a call isp_video_buffer_prepare_user and free the
 * pages table.
 */
static void isp_video_buffer_cleanup(struct isp_video_buffer *buf)
{
	enum dma_data_direction direction;
	unsigned int i;

	if (buf->queue->ops->buffer_cleanup)
		buf->queue->ops->buffer_cleanup(buf);

	if (!(buf->vm_flags & VM_PFNMAP)) {
		direction = buf->vbuf.type == V4L2_BUF_TYPE_VIDEO_CAPTURE
			  ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
		dma_unmap_sg(buf->queue->dev, buf->sglist, buf->sglen,
			     direction);
	}

	vfree(buf->sglist);
	buf->sglist = NULL;
	buf->sglen = 0;

	if (buf->pages != NULL) {
		isp_video_buffer_lock_vma(buf, 0);

		for (i = 0; i < buf->npages; ++i)
			page_cache_release(buf->pages[i]);

		vfree(buf->pages);
		buf->pages = NULL;
	}

	buf->npages = 0;
	buf->skip_cache = false;
}

/*
 * isp_video_buffer_prepare_user - Pin userspace VMA pages to memory.
 *
 * This function creates a list of pages for a userspace VMA. The number of
 * pages is first computed based on the buffer size, and pages are then
 * retrieved by a call to get_user_pages.
 *
 * Pages are pinned to memory by get_user_pages, making them available for DMA
 * transfers. However, due to memory management optimization, it seems the
 * get_user_pages doesn't guarantee that the pinned pages will not be written
 * to swap and removed from the userspace mapping(s). When this happens, a page
 * fault can be generated when accessing those unmapped pages.
 *
 * If the fault is triggered by a page table walk caused by VIPT cache
 * management operations, the page fault handler might oops if the MM semaphore
 * is held, as it can't handle kernel page faults in that case. To fix that, a
 * fixup entry needs to be added to the cache management code, or the userspace
 * VMA must be locked to avoid removing pages from the userspace mapping in the
 * first place.
 *
 * If the number of pages retrieved is smaller than the number required by the
 * buffer size, the function returns -EFAULT.
 */
static int isp_video_buffer_prepare_user(struct isp_video_buffer *buf)
{
	unsigned long data;
	unsigned int first;
	unsigned int last;
	int ret;

	data = buf->vbuf.m.userptr;
	first = (data & PAGE_MASK) >> PAGE_SHIFT;
	last = ((data + buf->vbuf.length - 1) & PAGE_MASK) >> PAGE_SHIFT;

	buf->offset = data & ~PAGE_MASK;
	buf->npages = last - first + 1;
	buf->pages = vmalloc(buf->npages * sizeof(buf->pages[0]));
	if (buf->pages == NULL)
		return -ENOMEM;

	down_read(&current->mm->mmap_sem);
	ret = get_user_pages(current, current->mm, data & PAGE_MASK,
			     buf->npages,
			     buf->vbuf.type == V4L2_BUF_TYPE_VIDEO_CAPTURE, 0,
			     buf->pages, NULL);
	up_read(&current->mm->mmap_sem);

	if (ret != buf->npages) {
		buf->npages = ret < 0 ? 0 : ret;
		isp_video_buffer_cleanup(buf);
		return -EFAULT;
	}

	ret = isp_video_buffer_lock_vma(buf, 1);
	if (ret < 0)
		isp_video_buffer_cleanup(buf);

	return ret;
}

/*
 * isp_video_buffer_prepare_pfnmap - Validate a VM_PFNMAP userspace buffer
 *
 * Userspace VM_PFNMAP buffers are supported only if they are contiguous in
 * memory and if they span a single VMA.
 *
 * Return 0 if the buffer is valid, or -EFAULT otherwise.
 */
static int isp_video_buffer_prepare_pfnmap(struct isp_video_buffer *buf)
{
	struct vm_area_struct *vma;
	unsigned long prev_pfn;
	unsigned long this_pfn;
	unsigned long start;
	unsigned long end;
	dma_addr_t pa;
	int ret = -EFAULT;

	start = buf->vbuf.m.userptr;
	end = buf->vbuf.m.userptr + buf->vbuf.length - 1;

	buf->offset = start & ~PAGE_MASK;
	buf->npages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
	buf->pages = NULL;

	down_read(&current->mm->mmap_sem);
	vma = find_vma(current->mm, start);
	if (vma == NULL || vma->vm_end < end)
		goto done;

	for (prev_pfn = 0; start <= end; start += PAGE_SIZE) {
		ret = follow_pfn(vma, start, &this_pfn);
		if (ret)
			goto done;

		if (prev_pfn == 0)
			pa = this_pfn << PAGE_SHIFT;
		else if (this_pfn != prev_pfn + 1) {
			ret = -EFAULT;
			goto done;
		}

		prev_pfn = this_pfn;
	}

	buf->paddr = pa + buf->offset;
	ret = 0;

done:
	up_read(&current->mm->mmap_sem);
	return ret;
}

/*
 * isp_video_buffer_prepare_vm_flags - Get VMA flags for a userspace address
 *
 * This function locates the VMAs for the buffer's userspace address and checks
 * that their flags match. The only flag that we need to care for at the moment
 * is VM_PFNMAP.
 *
 * The buffer vm_flags field is set to the first VMA flags.
 *
 * Return -EFAULT if no VMA can be found for part of the buffer, or if the VMAs
 * have incompatible flags.
 */
static int isp_video_buffer_prepare_vm_flags(struct isp_video_buffer *buf)
{
	struct vm_area_struct *vma;
	pgprot_t vm_page_prot;
	unsigned long start;
	unsigned long end;
	int ret = -EFAULT;

	start = buf->vbuf.m.userptr;
	end = buf->vbuf.m.userptr + buf->vbuf.length - 1;

	down_read(&current->mm->mmap_sem);

	do {
		vma = find_vma(current->mm, start);
		if (vma == NULL)
			goto done;

		if (start == buf->vbuf.m.userptr) {
			buf->vm_flags = vma->vm_flags;
			vm_page_prot = vma->vm_page_prot;
		}

		if ((buf->vm_flags ^ vma->vm_flags) & VM_PFNMAP)
			goto done;

		if (vm_page_prot != vma->vm_page_prot)
			goto done;

		start = vma->vm_end + 1;
	} while (vma->vm_end < end);

	/* Skip cache management to enhance performances for non-cached or
	 * write-combining buffers.
	 */
	if (vm_page_prot == pgprot_noncached(vm_page_prot) ||
	    vm_page_prot == pgprot_writecombine(vm_page_prot))
		buf->skip_cache = true;

	ret = 0;

done:
	up_read(&current->mm->mmap_sem);
	return ret;
}

/*
 * isp_video_buffer_prepare - Make a buffer ready for operation
 *
 * Preparing a buffer involves:
 *
 * - validating VMAs (userspace buffers only)
 * - locking pages and VMAs into memory (userspace buffers only)
 * - building page and scatter-gather lists
 * - mapping buffers for DMA operation
 * - performing driver-specific preparation
 *
 * The function must be called in userspace context with a valid mm context
 * (this excludes cleanup paths such as sys_close when the userspace process
 * segfaults).
 */
static int isp_video_buffer_prepare(struct isp_video_buffer *buf)
{
	enum dma_data_direction direction;
	int ret;

	switch (buf->vbuf.memory) {
	case V4L2_MEMORY_MMAP:
		ret = isp_video_buffer_sglist_kernel(buf);
		break;

	case V4L2_MEMORY_USERPTR:
		ret = isp_video_buffer_prepare_vm_flags(buf);
		if (ret < 0)
			return ret;

		if (buf->vm_flags & VM_PFNMAP) {
			ret = isp_video_buffer_prepare_pfnmap(buf);
			if (ret < 0)
				return ret;

			ret = isp_video_buffer_sglist_pfnmap(buf);
		} else {
			ret = isp_video_buffer_prepare_user(buf);
			if (ret < 0)
				return ret;

			ret = isp_video_buffer_sglist_user(buf);
		}
		break;

	default:
		return -EINVAL;
	}

	if (ret < 0)
		goto done;

	if (!(buf->vm_flags & VM_PFNMAP)) {
		direction = buf->vbuf.type == V4L2_BUF_TYPE_VIDEO_CAPTURE
			  ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
		ret = dma_map_sg(buf->queue->dev, buf->sglist, buf->sglen,
				 direction);
		if (ret != buf->sglen) {
			ret = -EFAULT;
			goto done;
		}
	}

	if (buf->queue->ops->buffer_prepare)
		ret = buf->queue->ops->buffer_prepare(buf);

done:
	if (ret < 0) {
		isp_video_buffer_cleanup(buf);
		return ret;
	}

	return ret;
}

/*
 * isp_video_queue_query - Query the status of a given buffer
 *
 * Locking: must be called with the queue lock held.
 */
static void isp_video_buffer_query(struct isp_video_buffer *buf,
				   struct v4l2_buffer *vbuf)
{
	memcpy(vbuf, &buf->vbuf, sizeof(*vbuf));

	if (buf->vma_use_count)
		vbuf->flags |= V4L2_BUF_FLAG_MAPPED;

	switch (buf->state) {
	case ISP_BUF_STATE_ERROR:
		vbuf->flags |= V4L2_BUF_FLAG_ERROR;
	case ISP_BUF_STATE_DONE:
		vbuf->flags |= V4L2_BUF_FLAG_DONE;
	case ISP_BUF_STATE_QUEUED:
	case ISP_BUF_STATE_ACTIVE:
		vbuf->flags |= V4L2_BUF_FLAG_QUEUED;
		break;
	case ISP_BUF_STATE_IDLE:
	default:
		break;
	}
}

/*
 * isp_video_buffer_wait - Wait for a buffer to be ready
 *
 * In non-blocking mode, return immediately with 0 if the buffer is ready or
 * -EAGAIN if the buffer is in the QUEUED or ACTIVE state.
 *
 * In blocking mode, wait (interruptibly but with no timeout) on the buffer wait
 * queue using the same condition.
 */
static int isp_video_buffer_wait(struct isp_video_buffer *buf, int nonblocking)
{
	if (nonblocking) {
		return (buf->state != ISP_BUF_STATE_QUEUED &&
			buf->state != ISP_BUF_STATE_ACTIVE)
			? 0 : -EAGAIN;
	}

	return wait_event_interruptible(buf->wait,
		buf->state != ISP_BUF_STATE_QUEUED &&
		buf->state != ISP_BUF_STATE_ACTIVE);
}

/* -----------------------------------------------------------------------------
 * Queue management
 */

/*
 * isp_video_queue_free - Free video buffers memory
 *
 * Buffers can only be freed if the queue isn't streaming and if no buffer is
 * mapped to userspace. Return -EBUSY if those conditions aren't statisfied.
 *
 * This function must be called with the queue lock held.
 */
static int isp_video_queue_free(struct isp_video_queue *queue)
{
	unsigned int i;

	if (queue->streaming)
		return -EBUSY;

	for (i = 0; i < queue->count; ++i) {
		if (queue->buffers[i]->vma_use_count != 0)
			return -EBUSY;
	}

	for (i = 0; i < queue->count; ++i) {
		struct isp_video_buffer *buf = queue->buffers[i];

		isp_video_buffer_cleanup(buf);

		vfree(buf->vaddr);
		buf->vaddr = NULL;

		kfree(buf);
		queue->buffers[i] = NULL;
	}

	INIT_LIST_HEAD(&queue->queue);
	queue->count = 0;
	return 0;
}

/*
 * isp_video_queue_alloc - Allocate video buffers memory
 *
 * This function must be called with the queue lock held.
 */
static int isp_video_queue_alloc(struct isp_video_queue *queue,
				 unsigned int nbuffers,
				 unsigned int size, enum v4l2_memory memory)
{
	struct isp_video_buffer *buf;
	unsigned int i;
	void *mem;
	int ret;

	/* Start by freeing the buffers. */
	ret = isp_video_queue_free(queue);
	if (ret < 0)
		return ret;

	/* Bail out of no buffers should be allocated. */
	if (nbuffers == 0)
		return 0;

	/* Initialize the allocated buffers. */
	for (i = 0; i < nbuffers; ++i) {
		buf = kzalloc(queue->bufsize, GFP_KERNEL);
		if (buf == NULL)
			break;

		if (memory == V4L2_MEMORY_MMAP) {
			/* Allocate video buffers memory for mmap mode. Align
			 * the size to the page size.
			 */
			mem = vmalloc_32_user(PAGE_ALIGN(size));
			if (mem == NULL) {
				kfree(buf);
				break;
			}

			buf->vbuf.m.offset = i * PAGE_ALIGN(size);
			buf->vaddr = mem;
		}

		buf->vbuf.index = i;
		buf->vbuf.length = size;
		buf->vbuf.type = queue->type;
		buf->vbuf.field = V4L2_FIELD_NONE;
		buf->vbuf.memory = memory;

		buf->queue = queue;
		init_waitqueue_head(&buf->wait);

		queue->buffers[i] = buf;
	}

	if (i == 0)
		return -ENOMEM;

	queue->count = i;
	return nbuffers;
}

/**
 * omap3isp_video_queue_cleanup - Clean up the video buffers queue
 * @queue: Video buffers queue
 *
 * Free all allocated resources and clean up the video buffers queue. The queue
 * must not be busy (no ongoing video stream) and buffers must have been
 * unmapped.
 *
 * Return 0 on success or -EBUSY if the queue is busy or buffers haven't been
 * unmapped.
 */
int omap3isp_video_queue_cleanup(struct isp_video_queue *queue)
{
	return isp_video_queue_free(queue);
}

/**
 * omap3isp_video_queue_init - Initialize the video buffers queue
 * @queue: Video buffers queue
 * @type: V4L2 buffer type (capture or output)
 * @ops: Driver-specific queue operations
 * @dev: Device used for DMA operations
 * @bufsize: Size of the driver-specific buffer structure
 *
 * Initialize the video buffers queue with the supplied parameters.
 *
 * The queue type must be one of V4L2_BUF_TYPE_VIDEO_CAPTURE or
 * V4L2_BUF_TYPE_VIDEO_OUTPUT. Other buffer types are not supported yet.
 *
 * Buffer objects will be allocated using the given buffer size to allow room
 * for driver-specific fields. Driver-specific buffer structures must start
 * with a struct isp_video_buffer field. Drivers with no driver-specific buffer
 * structure must pass the size of the isp_video_buffer structure in the bufsize
 * parameter.
 *
 * Return 0 on success.
 */
int omap3isp_video_queue_init(struct isp_video_queue *queue,
			      enum v4l2_buf_type type,
			      const struct isp_video_queue_operations *ops,
			      struct device *dev, unsigned int bufsize)
{
	INIT_LIST_HEAD(&queue->queue);
	mutex_init(&queue->lock);
	spin_lock_init(&queue->irqlock);

	queue->type = type;
	queue->ops = ops;
	queue->dev = dev;
	queue->bufsize = bufsize;

	return 0;
}

/* -----------------------------------------------------------------------------
 * V4L2 operations
 */

/**
 * omap3isp_video_queue_reqbufs - Allocate video buffers memory
 *
 * This function is intended to be used as a VIDIOC_REQBUFS ioctl handler. It
 * allocated video buffer objects and, for MMAP buffers, buffer memory.
 *
 * If the number of buffers is 0, all buffers are freed and the function returns
 * without performing any allocation.
 *
 * If the number of buffers is not 0, currently allocated buffers (if any) are
 * freed and the requested number of buffers are allocated. Depending on
 * driver-specific requirements and on memory availability, a number of buffer
 * smaller or bigger than requested can be allocated. This isn't considered as
 * an error.
 *
 * Return 0 on success or one of the following error codes:
 *
 * -EINVAL if the buffer type or index are invalid
 * -EBUSY if the queue is busy (streaming or buffers mapped)
 * -ENOMEM if the buffers can't be allocated due to an out-of-memory condition
 */
int omap3isp_video_queue_reqbufs(struct isp_video_queue *queue,
				 struct v4l2_requestbuffers *rb)
{
	unsigned int nbuffers = rb->count;
	unsigned int size;
	int ret;

	if (rb->type != queue->type)
		return -EINVAL;

	queue->ops->queue_prepare(queue, &nbuffers, &size);
	if (size == 0)
		return -EINVAL;

	nbuffers = min_t(unsigned int, nbuffers, ISP_VIDEO_MAX_BUFFERS);

	mutex_lock(&queue->lock);

	ret = isp_video_queue_alloc(queue, nbuffers, size, rb->memory);
	if (ret < 0)
		goto done;

	rb->count = ret;
	ret = 0;

done:
	mutex_unlock(&queue->lock);
	return ret;
}

/**
 * omap3isp_video_queue_querybuf - Query the status of a buffer in a queue
 *
 * This function is intended to be used as a VIDIOC_QUERYBUF ioctl handler. It
 * returns the status of a given video buffer.
 *
 * Return 0 on success or -EINVAL if the buffer type or index are invalid.
 */
int omap3isp_video_queue_querybuf(struct isp_video_queue *queue,
				  struct v4l2_buffer *vbuf)
{
	struct isp_video_buffer *buf;
	int ret = 0;

	if (vbuf->type != queue->type)
		return -EINVAL;

	mutex_lock(&queue->lock);

	if (vbuf->index >= queue->count) {
		ret = -EINVAL;
		goto done;
	}

	buf = queue->buffers[vbuf->index];
	isp_video_buffer_query(buf, vbuf);

done:
	mutex_unlock(&queue->lock);
	return ret;
}

/**
 * omap3isp_video_queue_qbuf - Queue a buffer
 *
 * This function is intended to be used as a VIDIOC_QBUF ioctl handler.
 *
 * The v4l2_buffer structure passed from userspace is first sanity tested. If
 * sane, the buffer is then processed and added to the main queue and, if the
 * queue is streaming, to the IRQ queue.
 *
 * Before being enqueued, USERPTR buffers are checked for address changes. If
 * the buffer has a different userspace address, the old memory area is unlocked
 * and the new memory area is locked.
 */
int omap3isp_video_queue_qbuf(struct isp_video_queue *queue,
			      struct v4l2_buffer *vbuf)
{
	struct isp_video_buffer *buf;
	unsigned long flags;
	int ret = -EINVAL;

	if (vbuf->type != queue->type)
		goto done;

	mutex_lock(&queue->lock);

	if (vbuf->index >= queue->count)
		goto done;

	buf = queue->buffers[vbuf->index];

	if (vbuf->memory != buf->vbuf.memory)
		goto done;

	if (buf->state != ISP_BUF_STATE_IDLE)
		goto done;

	if (vbuf->memory == V4L2_MEMORY_USERPTR &&
	    vbuf->length < buf->vbuf.length)
		goto done;

	if (vbuf->memory == V4L2_MEMORY_USERPTR &&
	    vbuf->m.userptr != buf->vbuf.m.userptr) {
		isp_video_buffer_cleanup(buf);
		buf->vbuf.m.userptr = vbuf->m.userptr;
		buf->prepared = 0;
	}

	if (!buf->prepared) {
		ret = isp_video_buffer_prepare(buf);
		if (ret < 0)
			goto done;
		buf->prepared = 1;
	}

	isp_video_buffer_cache_sync(buf);

	buf->state = ISP_BUF_STATE_QUEUED;
	list_add_tail(&buf->stream, &queue->queue);

	if (queue->streaming) {
		spin_lock_irqsave(&queue->irqlock, flags);
		queue->ops->buffer_queue(buf);
		spin_unlock_irqrestore(&queue->irqlock, flags);
	}

	ret = 0;

done:
	mutex_unlock(&queue->lock);
	return ret;
}

/**
 * omap3isp_video_queue_dqbuf - Dequeue a buffer
 *
 * This function is intended to be used as a VIDIOC_DQBUF ioctl handler.
 *
 * The v4l2_buffer structure passed from userspace is first sanity tested. If
 * sane, the buffer is then processed and added to the main queue and, if the
 * queue is streaming, to the IRQ queue.
 *
 * Before being enqueued, USERPTR buffers are checked for address changes. If
 * the buffer has a different userspace address, the old memory area is unlocked
 * and the new memory area is locked.
 */
int omap3isp_video_queue_dqbuf(struct isp_video_queue *queue,
			       struct v4l2_buffer *vbuf, int nonblocking)
{
	struct isp_video_buffer *buf;
	int ret;

	if (vbuf->type != queue->type)
		return -EINVAL;

	mutex_lock(&queue->lock);

	if (list_empty(&queue->queue)) {
		ret = -EINVAL;
		goto done;
	}

	buf = list_first_entry(&queue->queue, struct isp_video_buffer, stream);
	ret = isp_video_buffer_wait(buf, nonblocking);
	if (ret < 0)
		goto done;

	list_del(&buf->stream);

	isp_video_buffer_query(buf, vbuf);
	buf->state = ISP_BUF_STATE_IDLE;
	vbuf->flags &= ~V4L2_BUF_FLAG_QUEUED;

done:
	mutex_unlock(&queue->lock);
	return ret;
}

/**
 * omap3isp_video_queue_streamon - Start streaming
 *
 * This function is intended to be used as a VIDIOC_STREAMON ioctl handler. It
 * starts streaming on the queue and calls the buffer_queue operation for all
 * queued buffers.
 *
 * Return 0 on success.
 */
int omap3isp_video_queue_streamon(struct isp_video_queue *queue)
{
	struct isp_video_buffer *buf;
	unsigned long flags;

	mutex_lock(&queue->lock);

	if (queue->streaming)
		goto done;

	queue->streaming = 1;

	spin_lock_irqsave(&queue->irqlock, flags);
	list_for_each_entry(buf, &queue->queue, stream)
		queue->ops->buffer_queue(buf);
	spin_unlock_irqrestore(&queue->irqlock, flags);

done:
	mutex_unlock(&queue->lock);
	return 0;
}

/**
 * omap3isp_video_queue_streamoff - Stop streaming
 *
 * This function is intended to be used as a VIDIOC_STREAMOFF ioctl handler. It
 * stops streaming on the queue and wakes up all the buffers.
 *
 * Drivers must stop the hardware and synchronize with interrupt handlers and/or
 * delayed works before calling this function to make sure no buffer will be
 * touched by the driver and/or hardware.
 */
void omap3isp_video_queue_streamoff(struct isp_video_queue *queue)
{
	struct isp_video_buffer *buf;
	unsigned long flags;
	unsigned int i;

	mutex_lock(&queue->lock);

	if (!queue->streaming)
		goto done;

	queue->streaming = 0;

	spin_lock_irqsave(&queue->irqlock, flags);
	for (i = 0; i < queue->count; ++i) {
		buf = queue->buffers[i];

		if (buf->state == ISP_BUF_STATE_ACTIVE)
			wake_up(&buf->wait);

		buf->state = ISP_BUF_STATE_IDLE;
	}
	spin_unlock_irqrestore(&queue->irqlock, flags);

	INIT_LIST_HEAD(&queue->queue);

done:
	mutex_unlock(&queue->lock);
}

/**
 * omap3isp_video_queue_discard_done - Discard all buffers marked as DONE
 *
 * This function is intended to be used with suspend/resume operations. It
 * discards all 'done' buffers as they would be too old to be requested after
 * resume.
 *
 * Drivers must stop the hardware and synchronize with interrupt handlers and/or
 * delayed works before calling this function to make sure no buffer will be
 * touched by the driver and/or hardware.
 */
void omap3isp_video_queue_discard_done(struct isp_video_queue *queue)
{
	struct isp_video_buffer *buf;
	unsigned int i;

	mutex_lock(&queue->lock);

	if (!queue->streaming)
		goto done;

	for (i = 0; i < queue->count; ++i) {
		buf = queue->buffers[i];

		if (buf->state == ISP_BUF_STATE_DONE)
			buf->state = ISP_BUF_STATE_ERROR;
	}

done:
	mutex_unlock(&queue->lock);
}

static void isp_video_queue_vm_open(struct vm_area_struct *vma)
{
	struct isp_video_buffer *buf = vma->vm_private_data;

	buf->vma_use_count++;
}

static void isp_video_queue_vm_close(struct vm_area_struct *vma)
{
	struct isp_video_buffer *buf = vma->vm_private_data;

	buf->vma_use_count--;
}

static const struct vm_operations_struct isp_video_queue_vm_ops = {
	.open = isp_video_queue_vm_open,
	.close = isp_video_queue_vm_close,
};

/**
 * omap3isp_video_queue_mmap - Map buffers to userspace
 *
 * This function is intended to be used as an mmap() file operation handler. It
 * maps a buffer to userspace based on the VMA offset.
 *
 * Only buffers of memory type MMAP are supported.
 */
int omap3isp_video_queue_mmap(struct isp_video_queue *queue,
			 struct vm_area_struct *vma)
{
	struct isp_video_buffer *uninitialized_var(buf);
	unsigned long size;
	unsigned int i;
	int ret = 0;

	mutex_lock(&queue->lock);

	for (i = 0; i < queue->count; ++i) {
		buf = queue->buffers[i];
		if ((buf->vbuf.m.offset >> PAGE_SHIFT) == vma->vm_pgoff)
			break;
	}

	if (i == queue->count) {
		ret = -EINVAL;
		goto done;
	}

	size = vma->vm_end - vma->vm_start;

	if (buf->vbuf.memory != V4L2_MEMORY_MMAP ||
	    size != PAGE_ALIGN(buf->vbuf.length)) {
		ret = -EINVAL;
		goto done;
	}

	ret = remap_vmalloc_range(vma, buf->vaddr, 0);
	if (ret < 0)
		goto done;

	vma->vm_ops = &isp_video_queue_vm_ops;
	vma->vm_private_data = buf;
	isp_video_queue_vm_open(vma);

done:
	mutex_unlock(&queue->lock);
	return ret;
}

/**
 * omap3isp_video_queue_poll - Poll video queue state
 *
 * This function is intended to be used as a poll() file operation handler. It
 * polls the state of the video buffer at the front of the queue and returns an
 * events mask.
 *
 * If no buffer is present at the front of the queue, POLLERR is returned.
 */
unsigned int omap3isp_video_queue_poll(struct isp_video_queue *queue,
				       struct file *file, poll_table *wait)
{
	struct isp_video_buffer *buf;
	unsigned int mask = 0;

	mutex_lock(&queue->lock);
	if (list_empty(&queue->queue)) {
		mask |= POLLERR;
		goto done;
	}
	buf = list_first_entry(&queue->queue, struct isp_video_buffer, stream);

	poll_wait(file, &buf->wait, wait);
	if (buf->state == ISP_BUF_STATE_DONE ||
	    buf->state == ISP_BUF_STATE_ERROR) {
		if (queue->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
			mask |= POLLIN | POLLRDNORM;
		else
			mask |= POLLOUT | POLLWRNORM;
	}

done:
	mutex_unlock(&queue->lock);
	return mask;
}