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
/*
 *	ds2490.c  USB to one wire bridge
 *
 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/usb.h>
#include <linux/slab.h>

#include "../w1_int.h"
#include "../w1.h"

/* USB Standard */
/* USB Control request vendor type */
#define VENDOR				0x40

/* COMMAND TYPE CODES */
#define CONTROL_CMD			0x00
#define COMM_CMD			0x01
#define MODE_CMD			0x02

/* CONTROL COMMAND CODES */
#define CTL_RESET_DEVICE		0x0000
#define CTL_START_EXE			0x0001
#define CTL_RESUME_EXE			0x0002
#define CTL_HALT_EXE_IDLE		0x0003
#define CTL_HALT_EXE_DONE		0x0004
#define CTL_FLUSH_COMM_CMDS		0x0007
#define CTL_FLUSH_RCV_BUFFER		0x0008
#define CTL_FLUSH_XMT_BUFFER		0x0009
#define CTL_GET_COMM_CMDS		0x000A

/* MODE COMMAND CODES */
#define MOD_PULSE_EN			0x0000
#define MOD_SPEED_CHANGE_EN		0x0001
#define MOD_1WIRE_SPEED			0x0002
#define MOD_STRONG_PU_DURATION		0x0003
#define MOD_PULLDOWN_SLEWRATE		0x0004
#define MOD_PROG_PULSE_DURATION		0x0005
#define MOD_WRITE1_LOWTIME		0x0006
#define MOD_DSOW0_TREC			0x0007

/* COMMUNICATION COMMAND CODES */
#define COMM_ERROR_ESCAPE		0x0601
#define COMM_SET_DURATION		0x0012
#define COMM_BIT_IO			0x0020
#define COMM_PULSE			0x0030
#define COMM_1_WIRE_RESET		0x0042
#define COMM_BYTE_IO			0x0052
#define COMM_MATCH_ACCESS		0x0064
#define COMM_BLOCK_IO			0x0074
#define COMM_READ_STRAIGHT		0x0080
#define COMM_DO_RELEASE			0x6092
#define COMM_SET_PATH			0x00A2
#define COMM_WRITE_SRAM_PAGE		0x00B2
#define COMM_WRITE_EPROM		0x00C4
#define COMM_READ_CRC_PROT_PAGE		0x00D4
#define COMM_READ_REDIRECT_PAGE_CRC	0x21E4
#define COMM_SEARCH_ACCESS		0x00F4

/* Communication command bits */
#define COMM_TYPE			0x0008
#define COMM_SE				0x0008
#define COMM_D				0x0008
#define COMM_Z				0x0008
#define COMM_CH				0x0008
#define COMM_SM				0x0008
#define COMM_R				0x0008
#define COMM_IM				0x0001

#define COMM_PS				0x4000
#define COMM_PST			0x4000
#define COMM_CIB			0x4000
#define COMM_RTS			0x4000
#define COMM_DT				0x2000
#define COMM_SPU			0x1000
#define COMM_F				0x0800
#define COMM_NTF			0x0400
#define COMM_ICP			0x0200
#define COMM_RST			0x0100

#define PULSE_PROG			0x01
#define PULSE_SPUE			0x02

#define BRANCH_MAIN			0xCC
#define BRANCH_AUX			0x33

/* Status flags */
#define ST_SPUA				0x01  /* Strong Pull-up is active */
#define ST_PRGA				0x02  /* 12V programming pulse is being generated */
#define ST_12VP				0x04  /* external 12V programming voltage is present */
#define ST_PMOD				0x08  /* DS2490 powered from USB and external sources */
#define ST_HALT				0x10  /* DS2490 is currently halted */
#define ST_IDLE				0x20  /* DS2490 is currently idle */
#define ST_EPOF				0x80
/* Status transfer size, 16 bytes status, 16 byte result flags */
#define ST_SIZE				0x20

/* Result Register flags */
#define RR_DETECT			0xA5 /* New device detected */
#define RR_NRS				0x01 /* Reset no presence or ... */
#define RR_SH				0x02 /* short on reset or set path */
#define RR_APP				0x04 /* alarming presence on reset */
#define RR_VPP				0x08 /* 12V expected not seen */
#define RR_CMP				0x10 /* compare error */
#define RR_CRC				0x20 /* CRC error detected */
#define RR_RDP				0x40 /* redirected page */
#define RR_EOS				0x80 /* end of search error */

#define SPEED_NORMAL			0x00
#define SPEED_FLEXIBLE			0x01
#define SPEED_OVERDRIVE			0x02

#define NUM_EP				4
#define EP_CONTROL			0
#define EP_STATUS			1
#define EP_DATA_OUT			2
#define EP_DATA_IN			3

struct ds_device
{
	struct list_head	ds_entry;

	struct usb_device	*udev;
	struct usb_interface	*intf;

	int			ep[NUM_EP];

	/* Strong PullUp
	 * 0: pullup not active, else duration in milliseconds
	 */
	int			spu_sleep;
	/* spu_bit contains COMM_SPU or 0 depending on if the strong pullup
	 * should be active or not for writes.
	 */
	u16			spu_bit;

	u8			st_buf[ST_SIZE];
	u8			byte_buf;

	struct w1_bus_master	master;
};

struct ds_status
{
	u8			enable;
	u8			speed;
	u8			pullup_dur;
	u8			ppuls_dur;
	u8			pulldown_slew;
	u8			write1_time;
	u8			write0_time;
	u8			reserved0;
	u8			status;
	u8			command0;
	u8			command1;
	u8			command_buffer_status;
	u8			data_out_buffer_status;
	u8			data_in_buffer_status;
	u8			reserved1;
	u8			reserved2;
};

static struct usb_device_id ds_id_table [] = {
	{ USB_DEVICE(0x04fa, 0x2490) },
	{ },
};
MODULE_DEVICE_TABLE(usb, ds_id_table);

static int ds_probe(struct usb_interface *, const struct usb_device_id *);
static void ds_disconnect(struct usb_interface *);

static int ds_send_control(struct ds_device *, u16, u16);
static int ds_send_control_cmd(struct ds_device *, u16, u16);

static LIST_HEAD(ds_devices);
static DEFINE_MUTEX(ds_mutex);

static struct usb_driver ds_driver = {
	.name =		"DS9490R",
	.probe =	ds_probe,
	.disconnect =	ds_disconnect,
	.id_table =	ds_id_table,
};

static int ds_send_control_cmd(struct ds_device *dev, u16 value, u16 index)
{
	int err;

	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, dev->ep[EP_CONTROL]),
			CONTROL_CMD, VENDOR, value, index, NULL, 0, 1000);
	if (err < 0) {
		pr_err("Failed to send command control message %x.%x: err=%d.\n",
				value, index, err);
		return err;
	}

	return err;
}

static int ds_send_control_mode(struct ds_device *dev, u16 value, u16 index)
{
	int err;

	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, dev->ep[EP_CONTROL]),
			MODE_CMD, VENDOR, value, index, NULL, 0, 1000);
	if (err < 0) {
		pr_err("Failed to send mode control message %x.%x: err=%d.\n",
				value, index, err);
		return err;
	}

	return err;
}

static int ds_send_control(struct ds_device *dev, u16 value, u16 index)
{
	int err;

	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, dev->ep[EP_CONTROL]),
			COMM_CMD, VENDOR, value, index, NULL, 0, 1000);
	if (err < 0) {
		pr_err("Failed to send control message %x.%x: err=%d.\n",
				value, index, err);
		return err;
	}

	return err;
}

static inline void ds_print_msg(unsigned char *buf, unsigned char *str, int off)
{
	pr_info("%45s: %8x\n", str, buf[off]);
}

static void ds_dump_status(struct ds_device *dev, unsigned char *buf, int count)
{
	int i;

	pr_info("0x%x: count=%d, status: ", dev->ep[EP_STATUS], count);
	for (i=0; i<count; ++i)
		pr_info("%02x ", buf[i]);
	pr_info("\n");

	if (count >= 16) {
		ds_print_msg(buf, "enable flag", 0);
		ds_print_msg(buf, "1-wire speed", 1);
		ds_print_msg(buf, "strong pullup duration", 2);
		ds_print_msg(buf, "programming pulse duration", 3);
		ds_print_msg(buf, "pulldown slew rate control", 4);
		ds_print_msg(buf, "write-1 low time", 5);
		ds_print_msg(buf, "data sample offset/write-0 recovery time",
			6);
		ds_print_msg(buf, "reserved (test register)", 7);
		ds_print_msg(buf, "device status flags", 8);
		ds_print_msg(buf, "communication command byte 1", 9);
		ds_print_msg(buf, "communication command byte 2", 10);
		ds_print_msg(buf, "communication command buffer status", 11);
		ds_print_msg(buf, "1-wire data output buffer status", 12);
		ds_print_msg(buf, "1-wire data input buffer status", 13);
		ds_print_msg(buf, "reserved", 14);
		ds_print_msg(buf, "reserved", 15);
	}
	for (i = 16; i < count; ++i) {
		if (buf[i] == RR_DETECT) {
			ds_print_msg(buf, "new device detect", i);
			continue;
		}
		ds_print_msg(buf, "Result Register Value: ", i);
		if (buf[i] & RR_NRS)
			pr_info("NRS: Reset no presence or ...\n");
		if (buf[i] & RR_SH)
			pr_info("SH: short on reset or set path\n");
		if (buf[i] & RR_APP)
			pr_info("APP: alarming presence on reset\n");
		if (buf[i] & RR_VPP)
			pr_info("VPP: 12V expected not seen\n");
		if (buf[i] & RR_CMP)
			pr_info("CMP: compare error\n");
		if (buf[i] & RR_CRC)
			pr_info("CRC: CRC error detected\n");
		if (buf[i] & RR_RDP)
			pr_info("RDP: redirected page\n");
		if (buf[i] & RR_EOS)
			pr_info("EOS: end of search error\n");
	}
}

static int ds_recv_status(struct ds_device *dev, struct ds_status *st,
			  bool dump)
{
	int count, err;

	if (st)
		memset(st, 0, sizeof(*st));

	count = 0;
	err = usb_interrupt_msg(dev->udev,
				usb_rcvintpipe(dev->udev,
					       dev->ep[EP_STATUS]),
				dev->st_buf, sizeof(dev->st_buf),
				&count, 1000);
	if (err < 0) {
		pr_err("Failed to read 1-wire data from 0x%x: err=%d.\n",
		       dev->ep[EP_STATUS], err);
		return err;
	}

	if (dump)
		ds_dump_status(dev, dev->st_buf, count);

	if (st && count >= sizeof(*st))
		memcpy(st, dev->st_buf, sizeof(*st));

	return count;
}

static void ds_reset_device(struct ds_device *dev)
{
	ds_send_control_cmd(dev, CTL_RESET_DEVICE, 0);
	/* Always allow strong pullup which allow individual writes to use
	 * the strong pullup.
	 */
	if (ds_send_control_mode(dev, MOD_PULSE_EN, PULSE_SPUE))
		pr_err("ds_reset_device: Error allowing strong pullup\n");
	/* Chip strong pullup time was cleared. */
	if (dev->spu_sleep) {
		/* lower 4 bits are 0, see ds_set_pullup */
		u8 del = dev->spu_sleep>>4;
		if (ds_send_control(dev, COMM_SET_DURATION | COMM_IM, del))
			pr_err("ds_reset_device: Error setting duration\n");
	}
}

static int ds_recv_data(struct ds_device *dev, unsigned char *buf, int size)
{
	int count, err;

	/* Careful on size.  If size is less than what is available in
	 * the input buffer, the device fails the bulk transfer and
	 * clears the input buffer.  It could read the maximum size of
	 * the data buffer, but then do you return the first, last, or
	 * some set of the middle size bytes?  As long as the rest of
	 * the code is correct there will be size bytes waiting.  A
	 * call to ds_wait_status will wait until the device is idle
	 * and any data to be received would have been available.
	 */
	count = 0;
	err = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, dev->ep[EP_DATA_IN]),
				buf, size, &count, 1000);
	if (err < 0) {
		pr_info("Clearing ep0x%x.\n", dev->ep[EP_DATA_IN]);
		usb_clear_halt(dev->udev, usb_rcvbulkpipe(dev->udev, dev->ep[EP_DATA_IN]));
		ds_recv_status(dev, NULL, true);
		return err;
	}

#if 0
	{
		int i;

		printk("%s: count=%d: ", __func__, count);
		for (i=0; i<count; ++i)
			printk("%02x ", buf[i]);
		printk("\n");
	}
#endif
	return count;
}

static int ds_send_data(struct ds_device *dev, unsigned char *buf, int len)
{
	int count, err;

	count = 0;
	err = usb_bulk_msg(dev->udev, usb_sndbulkpipe(dev->udev, dev->ep[EP_DATA_OUT]), buf, len, &count, 1000);
	if (err < 0) {
		pr_err("Failed to write 1-wire data to ep0x%x: "
			"err=%d.\n", dev->ep[EP_DATA_OUT], err);
		return err;
	}

	return err;
}

#if 0

int ds_stop_pulse(struct ds_device *dev, int limit)
{
	struct ds_status st;
	int count = 0, err = 0;

	do {
		err = ds_send_control(dev, CTL_HALT_EXE_IDLE, 0);
		if (err)
			break;
		err = ds_send_control(dev, CTL_RESUME_EXE, 0);
		if (err)
			break;
		err = ds_recv_status(dev, &st, false);
		if (err)
			break;

		if ((st.status & ST_SPUA) == 0) {
			err = ds_send_control_mode(dev, MOD_PULSE_EN, 0);
			if (err)
				break;
		}
	} while(++count < limit);

	return err;
}

int ds_detect(struct ds_device *dev, struct ds_status *st)
{
	int err;

	err = ds_send_control_cmd(dev, CTL_RESET_DEVICE, 0);
	if (err)
		return err;

	err = ds_send_control(dev, COMM_SET_DURATION | COMM_IM, 0);
	if (err)
		return err;

	err = ds_send_control(dev, COMM_SET_DURATION | COMM_IM | COMM_TYPE, 0x40);
	if (err)
		return err;

	err = ds_send_control_mode(dev, MOD_PULSE_EN, PULSE_PROG);
	if (err)
		return err;

	err = ds_dump_status(dev, st);

	return err;
}

#endif  /*  0  */

static int ds_wait_status(struct ds_device *dev, struct ds_status *st)
{
	int err, count = 0;

	do {
		st->status = 0;
		err = ds_recv_status(dev, st, false);
#if 0
		if (err >= 0) {
			int i;
			printk("0x%x: count=%d, status: ", dev->ep[EP_STATUS], err);
			for (i=0; i<err; ++i)
				printk("%02x ", dev->st_buf[i]);
			printk("\n");
		}
#endif
	} while (!(st->status & ST_IDLE) && !(err < 0) && ++count < 100);

	if (err >= 16 && st->status & ST_EPOF) {
		pr_info("Resetting device after ST_EPOF.\n");
		ds_reset_device(dev);
		/* Always dump the device status. */
		count = 101;
	}

	/* Dump the status for errors or if there is extended return data.
	 * The extended status includes new device detection (maybe someone
	 * can do something with it).
	 */
	if (err > 16 || count >= 100 || err < 0)
		ds_dump_status(dev, dev->st_buf, err);

	/* Extended data isn't an error.  Well, a short is, but the dump
	 * would have already told the user that and we can't do anything
	 * about it in software anyway.
	 */
	if (count >= 100 || err < 0)
		return -1;
	else
		return 0;
}

static int ds_reset(struct ds_device *dev)
{
	int err;

	/* Other potentionally interesting flags for reset.
	 *
	 * COMM_NTF: Return result register feedback.  This could be used to
	 * detect some conditions such as short, alarming presence, or
	 * detect if a new device was detected.
	 *
	 * COMM_SE which allows SPEED_NORMAL, SPEED_FLEXIBLE, SPEED_OVERDRIVE:
	 * Select the data transfer rate.
	 */
	err = ds_send_control(dev, COMM_1_WIRE_RESET | COMM_IM, SPEED_NORMAL);
	if (err)
		return err;

	return 0;
}

#if 0
static int ds_set_speed(struct ds_device *dev, int speed)
{
	int err;

	if (speed != SPEED_NORMAL && speed != SPEED_FLEXIBLE && speed != SPEED_OVERDRIVE)
		return -EINVAL;

	if (speed != SPEED_OVERDRIVE)
		speed = SPEED_FLEXIBLE;

	speed &= 0xff;

	err = ds_send_control_mode(dev, MOD_1WIRE_SPEED, speed);
	if (err)
		return err;

	return err;
}
#endif  /*  0  */

static int ds_set_pullup(struct ds_device *dev, int delay)
{
	int err = 0;
	u8 del = 1 + (u8)(delay >> 4);
	/* Just storing delay would not get the trunication and roundup. */
	int ms = del<<4;

	/* Enable spu_bit if a delay is set. */
	dev->spu_bit = delay ? COMM_SPU : 0;
	/* If delay is zero, it has already been disabled, if the time is
	 * the same as the hardware was last programmed to, there is also
	 * nothing more to do.  Compare with the recalculated value ms
	 * rather than del or delay which can have a different value.
	 */
	if (delay == 0 || ms == dev->spu_sleep)
		return err;

	err = ds_send_control(dev, COMM_SET_DURATION | COMM_IM, del);
	if (err)
		return err;

	dev->spu_sleep = ms;

	return err;
}

static int ds_touch_bit(struct ds_device *dev, u8 bit, u8 *tbit)
{
	int err;
	struct ds_status st;

	err = ds_send_control(dev, COMM_BIT_IO | COMM_IM | (bit ? COMM_D : 0),
		0);
	if (err)
		return err;

	ds_wait_status(dev, &st);

	err = ds_recv_data(dev, tbit, sizeof(*tbit));
	if (err < 0)
		return err;

	return 0;
}

#if 0
static int ds_write_bit(struct ds_device *dev, u8 bit)
{
	int err;
	struct ds_status st;

	/* Set COMM_ICP to write without a readback.  Note, this will
	 * produce one time slot, a down followed by an up with COMM_D
	 * only determing the timing.
	 */
	err = ds_send_control(dev, COMM_BIT_IO | COMM_IM | COMM_ICP |
		(bit ? COMM_D : 0), 0);
	if (err)
		return err;

	ds_wait_status(dev, &st);

	return 0;
}
#endif

static int ds_write_byte(struct ds_device *dev, u8 byte)
{
	int err;
	struct ds_status st;

	err = ds_send_control(dev, COMM_BYTE_IO | COMM_IM | dev->spu_bit, byte);
	if (err)
		return err;

	if (dev->spu_bit)
		msleep(dev->spu_sleep);

	err = ds_wait_status(dev, &st);
	if (err)
		return err;

	err = ds_recv_data(dev, &dev->byte_buf, 1);
	if (err < 0)
		return err;

	return !(byte == dev->byte_buf);
}

static int ds_read_byte(struct ds_device *dev, u8 *byte)
{
	int err;
	struct ds_status st;

	err = ds_send_control(dev, COMM_BYTE_IO | COMM_IM , 0xff);
	if (err)
		return err;

	ds_wait_status(dev, &st);

	err = ds_recv_data(dev, byte, sizeof(*byte));
	if (err < 0)
		return err;

	return 0;
}

static int ds_read_block(struct ds_device *dev, u8 *buf, int len)
{
	struct ds_status st;
	int err;

	if (len > 64*1024)
		return -E2BIG;

	memset(buf, 0xFF, len);

	err = ds_send_data(dev, buf, len);
	if (err < 0)
		return err;

	err = ds_send_control(dev, COMM_BLOCK_IO | COMM_IM, len);
	if (err)
		return err;

	ds_wait_status(dev, &st);

	memset(buf, 0x00, len);
	err = ds_recv_data(dev, buf, len);

	return err;
}

static int ds_write_block(struct ds_device *dev, u8 *buf, int len)
{
	int err;
	struct ds_status st;

	err = ds_send_data(dev, buf, len);
	if (err < 0)
		return err;

	err = ds_send_control(dev, COMM_BLOCK_IO | COMM_IM | dev->spu_bit, len);
	if (err)
		return err;

	if (dev->spu_bit)
		msleep(dev->spu_sleep);

	ds_wait_status(dev, &st);

	err = ds_recv_data(dev, buf, len);
	if (err < 0)
		return err;

	return !(err == len);
}

static void ds9490r_search(void *data, struct w1_master *master,
	u8 search_type, w1_slave_found_callback callback)
{
	/* When starting with an existing id, the first id returned will
	 * be that device (if it is still on the bus most likely).
	 *
	 * If the number of devices found is less than or equal to the
	 * search_limit, that number of IDs will be returned.  If there are
	 * more, search_limit IDs will be returned followed by a non-zero
	 * discrepency value.
	 */
	struct ds_device *dev = data;
	int err;
	u16 value, index;
	struct ds_status st;
	int search_limit;
	int found = 0;
	int i;

	/* DS18b20 spec, 13.16 ms per device, 75 per second, sleep for
	 * discovering 8 devices (1 bulk transfer and 1/2 FIFO size) at a time.
	 */
	const unsigned long jtime = msecs_to_jiffies(1000*8/75);
	/* FIFO 128 bytes, bulk packet size 64, read a multiple of the
	 * packet size.
	 */
	const size_t bufsize = 2 * 64;
	u64 *buf;

	buf = kmalloc(bufsize, GFP_KERNEL);
	if (!buf)
		return;

	mutex_lock(&master->bus_mutex);

	/* address to start searching at */
	if (ds_send_data(dev, (u8 *)&master->search_id, 8) < 0)
		goto search_out;
	master->search_id = 0;

	value = COMM_SEARCH_ACCESS | COMM_IM | COMM_RST | COMM_SM | COMM_F |
		COMM_RTS;
	search_limit = master->max_slave_count;
	if (search_limit > 255)
		search_limit = 0;
	index = search_type | (search_limit << 8);
	if (ds_send_control(dev, value, index) < 0)
		goto search_out;

	do {
		schedule_timeout(jtime);

		err = ds_recv_status(dev, &st, false);
		if (err < 0 || err < sizeof(st))
			break;

		if (st.data_in_buffer_status) {
			/* Bulk in can receive partial ids, but when it does
			 * they fail crc and will be discarded anyway.
			 * That has only been seen when status in buffer
			 * is 0 and bulk is read anyway, so don't read
			 * bulk without first checking if status says there
			 * is data to read.
			 */
			err = ds_recv_data(dev, (u8 *)buf, bufsize);
			if (err < 0)
				break;
			for (i = 0; i < err/8; ++i) {
				++found;
				if (found <= search_limit)
					callback(master, buf[i]);
				/* can't know if there will be a discrepancy
				 * value after until the next id */
				if (found == search_limit)
					master->search_id = buf[i];
			}
		}

		if (test_bit(W1_ABORT_SEARCH, &master->flags))
			break;
	} while (!(st.status & (ST_IDLE | ST_HALT)));

	/* only continue the search if some weren't found */
	if (found <= search_limit) {
		master->search_id = 0;
	} else if (!test_bit(W1_WARN_MAX_COUNT, &master->flags)) {
		/* Only max_slave_count will be scanned in a search,
		 * but it will start where it left off next search
		 * until all ids are identified and then it will start
		 * over.  A continued search will report the previous
		 * last id as the first id (provided it is still on the
		 * bus).
		 */
		dev_info(&dev->udev->dev, "%s: max_slave_count %d reached, "
			"will continue next search.\n", __func__,
			master->max_slave_count);
		set_bit(W1_WARN_MAX_COUNT, &master->flags);
	}
search_out:
	mutex_unlock(&master->bus_mutex);
	kfree(buf);
}

#if 0
/*
 * FIXME: if this disabled code is ever used in the future all ds_send_data()
 * calls must be changed to use a DMAable buffer.
 */
static int ds_match_access(struct ds_device *dev, u64 init)
{
	int err;
	struct ds_status st;

	err = ds_send_data(dev, (unsigned char *)&init, sizeof(init));
	if (err)
		return err;

	ds_wait_status(dev, &st);

	err = ds_send_control(dev, COMM_MATCH_ACCESS | COMM_IM | COMM_RST, 0x0055);
	if (err)
		return err;

	ds_wait_status(dev, &st);

	return 0;
}

static int ds_set_path(struct ds_device *dev, u64 init)
{
	int err;
	struct ds_status st;
	u8 buf[9];

	memcpy(buf, &init, 8);
	buf[8] = BRANCH_MAIN;

	err = ds_send_data(dev, buf, sizeof(buf));
	if (err)
		return err;

	ds_wait_status(dev, &st);

	err = ds_send_control(dev, COMM_SET_PATH | COMM_IM | COMM_RST, 0);
	if (err)
		return err;

	ds_wait_status(dev, &st);

	return 0;
}

#endif  /*  0  */

static u8 ds9490r_touch_bit(void *data, u8 bit)
{
	struct ds_device *dev = data;

	if (ds_touch_bit(dev, bit, &dev->byte_buf))
		return 0;

	return dev->byte_buf;
}

#if 0
static void ds9490r_write_bit(void *data, u8 bit)
{
	struct ds_device *dev = data;

	ds_write_bit(dev, bit);
}

static u8 ds9490r_read_bit(void *data)
{
	struct ds_device *dev = data;
	int err;

	err = ds_touch_bit(dev, 1, &dev->byte_buf);
	if (err)
		return 0;

	return dev->byte_buf & 1;
}
#endif

static void ds9490r_write_byte(void *data, u8 byte)
{
	struct ds_device *dev = data;

	ds_write_byte(dev, byte);
}

static u8 ds9490r_read_byte(void *data)
{
	struct ds_device *dev = data;
	int err;

	err = ds_read_byte(dev, &dev->byte_buf);
	if (err)
		return 0;

	return dev->byte_buf;
}

static void ds9490r_write_block(void *data, const u8 *buf, int len)
{
	struct ds_device *dev = data;
	u8 *tbuf;

	if (len <= 0)
		return;

	tbuf = kmemdup(buf, len, GFP_KERNEL);
	if (!tbuf)
		return;

	ds_write_block(dev, tbuf, len);

	kfree(tbuf);
}

static u8 ds9490r_read_block(void *data, u8 *buf, int len)
{
	struct ds_device *dev = data;
	int err;
	u8 *tbuf;

	if (len <= 0)
		return 0;

	tbuf = kmalloc(len, GFP_KERNEL);
	if (!tbuf)
		return 0;

	err = ds_read_block(dev, tbuf, len);
	if (err >= 0)
		memcpy(buf, tbuf, len);

	kfree(tbuf);

	return err >= 0 ? len : 0;
}

static u8 ds9490r_reset(void *data)
{
	struct ds_device *dev = data;
	int err;

	err = ds_reset(dev);
	if (err)
		return 1;

	return 0;
}

static u8 ds9490r_set_pullup(void *data, int delay)
{
	struct ds_device *dev = data;

	if (ds_set_pullup(dev, delay))
		return 1;

	return 0;
}

static int ds_w1_init(struct ds_device *dev)
{
	memset(&dev->master, 0, sizeof(struct w1_bus_master));

	/* Reset the device as it can be in a bad state.
	 * This is necessary because a block write will wait for data
	 * to be placed in the output buffer and block any later
	 * commands which will keep accumulating and the device will
	 * not be idle.  Another case is removing the ds2490 module
	 * while a bus search is in progress, somehow a few commands
	 * get through, but the input transfers fail leaving data in
	 * the input buffer.  This will cause the next read to fail
	 * see the note in ds_recv_data.
	 */
	ds_reset_device(dev);

	dev->master.data	= dev;
	dev->master.touch_bit	= &ds9490r_touch_bit;
	/* read_bit and write_bit in w1_bus_master are expected to set and
	 * sample the line level.  For write_bit that means it is expected to
	 * set it to that value and leave it there.  ds2490 only supports an
	 * individual time slot at the lowest level.  The requirement from
	 * pulling the bus state down to reading the state is 15us, something
	 * that isn't realistic on the USB bus anyway.
	dev->master.read_bit	= &ds9490r_read_bit;
	dev->master.write_bit	= &ds9490r_write_bit;
	*/
	dev->master.read_byte	= &ds9490r_read_byte;
	dev->master.write_byte	= &ds9490r_write_byte;
	dev->master.read_block	= &ds9490r_read_block;
	dev->master.write_block	= &ds9490r_write_block;
	dev->master.reset_bus	= &ds9490r_reset;
	dev->master.set_pullup	= &ds9490r_set_pullup;
	dev->master.search	= &ds9490r_search;

	return w1_add_master_device(&dev->master);
}

static void ds_w1_fini(struct ds_device *dev)
{
	w1_remove_master_device(&dev->master);
}

static int ds_probe(struct usb_interface *intf,
		    const struct usb_device_id *udev_id)
{
	struct usb_device *udev = interface_to_usbdev(intf);
	struct usb_endpoint_descriptor *endpoint;
	struct usb_host_interface *iface_desc;
	struct ds_device *dev;
	int i, err, alt;

	dev = kzalloc(sizeof(struct ds_device), GFP_KERNEL);
	if (!dev) {
		pr_info("Failed to allocate new DS9490R structure.\n");
		return -ENOMEM;
	}
	dev->udev = usb_get_dev(udev);
	if (!dev->udev) {
		err = -ENOMEM;
		goto err_out_free;
	}
	memset(dev->ep, 0, sizeof(dev->ep));

	usb_set_intfdata(intf, dev);

	err = usb_reset_configuration(dev->udev);
	if (err) {
		dev_err(&dev->udev->dev,
			"Failed to reset configuration: err=%d.\n", err);
		goto err_out_clear;
	}

	/* alternative 3, 1ms interrupt (greatly speeds search), 64 byte bulk */
	alt = 3;
	err = usb_set_interface(dev->udev,
		intf->altsetting[alt].desc.bInterfaceNumber, alt);
	if (err) {
		dev_err(&dev->udev->dev, "Failed to set alternative setting %d "
			"for %d interface: err=%d.\n", alt,
			intf->altsetting[alt].desc.bInterfaceNumber, err);
		goto err_out_clear;
	}

	iface_desc = &intf->altsetting[alt];
	if (iface_desc->desc.bNumEndpoints != NUM_EP-1) {
		pr_info("Num endpoints=%d. It is not DS9490R.\n",
			iface_desc->desc.bNumEndpoints);
		err = -EINVAL;
		goto err_out_clear;
	}

	/*
	 * This loop doesn'd show control 0 endpoint,
	 * so we will fill only 1-3 endpoints entry.
	 */
	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
		endpoint = &iface_desc->endpoint[i].desc;

		dev->ep[i+1] = endpoint->bEndpointAddress;
#if 0
		printk("%d: addr=%x, size=%d, dir=%s, type=%x\n",
			i, endpoint->bEndpointAddress, le16_to_cpu(endpoint->wMaxPacketSize),
			(endpoint->bEndpointAddress & USB_DIR_IN)?"IN":"OUT",
			endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK);
#endif
	}

	err = ds_w1_init(dev);
	if (err)
		goto err_out_clear;

	mutex_lock(&ds_mutex);
	list_add_tail(&dev->ds_entry, &ds_devices);
	mutex_unlock(&ds_mutex);

	return 0;

err_out_clear:
	usb_set_intfdata(intf, NULL);
	usb_put_dev(dev->udev);
err_out_free:
	kfree(dev);
	return err;
}

static void ds_disconnect(struct usb_interface *intf)
{
	struct ds_device *dev;

	dev = usb_get_intfdata(intf);
	if (!dev)
		return;

	mutex_lock(&ds_mutex);
	list_del(&dev->ds_entry);
	mutex_unlock(&ds_mutex);

	ds_w1_fini(dev);

	usb_set_intfdata(intf, NULL);

	usb_put_dev(dev->udev);
	kfree(dev);
}

module_usb_driver(ds_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
MODULE_DESCRIPTION("DS2490 USB <-> W1 bus master driver (DS9490*)");