Linux Audio

Check our new training course

Embedded Linux Audio

Check our new training course
with Creative Commons CC-BY-SA
lecture materials

Bootlin logo

Elixir Cross Referencer

Loading...
   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
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
// SPDX-License-Identifier: GPL-2.0+
/*
 * Linux on zSeries Channel Measurement Facility support
 *
 * Copyright IBM Corp. 2000, 2006
 *
 * Authors: Arnd Bergmann <arndb@de.ibm.com>
 *	    Cornelia Huck <cornelia.huck@de.ibm.com>
 *
 * original idea from Natarajan Krishnaswami <nkrishna@us.ibm.com>
 */

#define KMSG_COMPONENT "cio"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/memblock.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/export.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/timex.h>	/* get_tod_clock() */

#include <asm/ccwdev.h>
#include <asm/cio.h>
#include <asm/cmb.h>
#include <asm/div64.h>

#include "cio.h"
#include "css.h"
#include "device.h"
#include "ioasm.h"
#include "chsc.h"

/*
 * parameter to enable cmf during boot, possible uses are:
 *  "s390cmf" -- enable cmf and allocate 2 MB of ram so measuring can be
 *               used on any subchannel
 *  "s390cmf=<num>" -- enable cmf and allocate enough memory to measure
 *                     <num> subchannel, where <num> is an integer
 *                     between 1 and 65535, default is 1024
 */
#define ARGSTRING "s390cmf"

/* indices for READCMB */
enum cmb_index {
	avg_utilization = -1,
 /* basic and exended format: */
	cmb_ssch_rsch_count = 0,
	cmb_sample_count,
	cmb_device_connect_time,
	cmb_function_pending_time,
	cmb_device_disconnect_time,
	cmb_control_unit_queuing_time,
	cmb_device_active_only_time,
 /* extended format only: */
	cmb_device_busy_time,
	cmb_initial_command_response_time,
};

/**
 * enum cmb_format - types of supported measurement block formats
 *
 * @CMF_BASIC:      traditional channel measurement blocks supported
 *		    by all machines that we run on
 * @CMF_EXTENDED:   improved format that was introduced with the z990
 *		    machine
 * @CMF_AUTODETECT: default: use extended format when running on a machine
 *		    supporting extended format, otherwise fall back to
 *		    basic format
 */
enum cmb_format {
	CMF_BASIC,
	CMF_EXTENDED,
	CMF_AUTODETECT = -1,
};

/*
 * format - actual format for all measurement blocks
 *
 * The format module parameter can be set to a value of 0 (zero)
 * or 1, indicating basic or extended format as described for
 * enum cmb_format.
 */
static int format = CMF_AUTODETECT;
module_param(format, bint, 0444);

/**
 * struct cmb_operations - functions to use depending on cmb_format
 *
 * Most of these functions operate on a struct ccw_device. There is only
 * one instance of struct cmb_operations because the format of the measurement
 * data is guaranteed to be the same for every ccw_device.
 *
 * @alloc:	allocate memory for a channel measurement block,
 *		either with the help of a special pool or with kmalloc
 * @free:	free memory allocated with @alloc
 * @set:	enable or disable measurement
 * @read:	read a measurement entry at an index
 * @readall:	read a measurement block in a common format
 * @reset:	clear the data in the associated measurement block and
 *		reset its time stamp
 */
struct cmb_operations {
	int  (*alloc)  (struct ccw_device *);
	void (*free)   (struct ccw_device *);
	int  (*set)    (struct ccw_device *, u32);
	u64  (*read)   (struct ccw_device *, int);
	int  (*readall)(struct ccw_device *, struct cmbdata *);
	void (*reset)  (struct ccw_device *);
/* private: */
	struct attribute_group *attr_group;
};
static struct cmb_operations *cmbops;

struct cmb_data {
	void *hw_block;   /* Pointer to block updated by hardware */
	void *last_block; /* Last changed block copied from hardware block */
	int size;	  /* Size of hw_block and last_block */
	unsigned long long last_update;  /* when last_block was updated */
};

/*
 * Our user interface is designed in terms of nanoseconds,
 * while the hardware measures total times in its own
 * unit.
 */
static inline u64 time_to_nsec(u32 value)
{
	return ((u64)value) * 128000ull;
}

/*
 * Users are usually interested in average times,
 * not accumulated time.
 * This also helps us with atomicity problems
 * when reading sinlge values.
 */
static inline u64 time_to_avg_nsec(u32 value, u32 count)
{
	u64 ret;

	/* no samples yet, avoid division by 0 */
	if (count == 0)
		return 0;

	/* value comes in units of 128 µsec */
	ret = time_to_nsec(value);
	do_div(ret, count);

	return ret;
}

#define CMF_OFF 0
#define CMF_ON	2

/*
 * Activate or deactivate the channel monitor. When area is NULL,
 * the monitor is deactivated. The channel monitor needs to
 * be active in order to measure subchannels, which also need
 * to be enabled.
 */
static inline void cmf_activate(void *area, unsigned int onoff)
{
	/* activate channel measurement */
	asm volatile(
		"	lgr	1,%[r1]\n"
		"	lgr	2,%[mbo]\n"
		"	schm\n"
		:
		: [r1] "d" ((unsigned long)onoff), [mbo] "d" (area)
		: "1", "2");
}

static int set_schib(struct ccw_device *cdev, u32 mme, int mbfc,
		     unsigned long address)
{
	struct subchannel *sch = to_subchannel(cdev->dev.parent);
	int ret;

	sch->config.mme = mme;
	sch->config.mbfc = mbfc;
	/* address can be either a block address or a block index */
	if (mbfc)
		sch->config.mba = address;
	else
		sch->config.mbi = address;

	ret = cio_commit_config(sch);
	if (!mme && ret == -ENODEV) {
		/*
		 * The task was to disable measurement block updates but
		 * the subchannel is already gone. Report success.
		 */
		ret = 0;
	}
	return ret;
}

struct set_schib_struct {
	u32 mme;
	int mbfc;
	unsigned long address;
	wait_queue_head_t wait;
	int ret;
};

#define CMF_PENDING 1
#define SET_SCHIB_TIMEOUT (10 * HZ)

static int set_schib_wait(struct ccw_device *cdev, u32 mme,
			  int mbfc, unsigned long address)
{
	struct set_schib_struct set_data;
	int ret = -ENODEV;

	spin_lock_irq(cdev->ccwlock);
	if (!cdev->private->cmb)
		goto out;

	ret = set_schib(cdev, mme, mbfc, address);
	if (ret != -EBUSY)
		goto out;

	/* if the device is not online, don't even try again */
	if (cdev->private->state != DEV_STATE_ONLINE)
		goto out;

	init_waitqueue_head(&set_data.wait);
	set_data.mme = mme;
	set_data.mbfc = mbfc;
	set_data.address = address;
	set_data.ret = CMF_PENDING;

	cdev->private->state = DEV_STATE_CMFCHANGE;
	cdev->private->cmb_wait = &set_data;
	spin_unlock_irq(cdev->ccwlock);

	ret = wait_event_interruptible_timeout(set_data.wait,
					       set_data.ret != CMF_PENDING,
					       SET_SCHIB_TIMEOUT);
	spin_lock_irq(cdev->ccwlock);
	if (ret <= 0) {
		if (set_data.ret == CMF_PENDING) {
			set_data.ret = (ret == 0) ? -ETIME : ret;
			if (cdev->private->state == DEV_STATE_CMFCHANGE)
				cdev->private->state = DEV_STATE_ONLINE;
		}
	}
	cdev->private->cmb_wait = NULL;
	ret = set_data.ret;
out:
	spin_unlock_irq(cdev->ccwlock);
	return ret;
}

void retry_set_schib(struct ccw_device *cdev)
{
	struct set_schib_struct *set_data = cdev->private->cmb_wait;

	if (!set_data)
		return;

	set_data->ret = set_schib(cdev, set_data->mme, set_data->mbfc,
				  set_data->address);
	wake_up(&set_data->wait);
}

static int cmf_copy_block(struct ccw_device *cdev)
{
	struct subchannel *sch = to_subchannel(cdev->dev.parent);
	struct cmb_data *cmb_data;
	void *hw_block;

	if (cio_update_schib(sch))
		return -ENODEV;

	if (scsw_fctl(&sch->schib.scsw) & SCSW_FCTL_START_FUNC) {
		/* Don't copy if a start function is in progress. */
		if ((!(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_SUSPENDED)) &&
		    (scsw_actl(&sch->schib.scsw) &
		     (SCSW_ACTL_DEVACT | SCSW_ACTL_SCHACT)) &&
		    (!(scsw_stctl(&sch->schib.scsw) & SCSW_STCTL_SEC_STATUS)))
			return -EBUSY;
	}
	cmb_data = cdev->private->cmb;
	hw_block = cmb_data->hw_block;
	memcpy(cmb_data->last_block, hw_block, cmb_data->size);
	cmb_data->last_update = get_tod_clock();
	return 0;
}

struct copy_block_struct {
	wait_queue_head_t wait;
	int ret;
};

static int cmf_cmb_copy_wait(struct ccw_device *cdev)
{
	struct copy_block_struct copy_block;
	int ret = -ENODEV;

	spin_lock_irq(cdev->ccwlock);
	if (!cdev->private->cmb)
		goto out;

	ret = cmf_copy_block(cdev);
	if (ret != -EBUSY)
		goto out;

	if (cdev->private->state != DEV_STATE_ONLINE)
		goto out;

	init_waitqueue_head(&copy_block.wait);
	copy_block.ret = CMF_PENDING;

	cdev->private->state = DEV_STATE_CMFUPDATE;
	cdev->private->cmb_wait = &copy_block;
	spin_unlock_irq(cdev->ccwlock);

	ret = wait_event_interruptible(copy_block.wait,
				       copy_block.ret != CMF_PENDING);
	spin_lock_irq(cdev->ccwlock);
	if (ret) {
		if (copy_block.ret == CMF_PENDING) {
			copy_block.ret = -ERESTARTSYS;
			if (cdev->private->state == DEV_STATE_CMFUPDATE)
				cdev->private->state = DEV_STATE_ONLINE;
		}
	}
	cdev->private->cmb_wait = NULL;
	ret = copy_block.ret;
out:
	spin_unlock_irq(cdev->ccwlock);
	return ret;
}

void cmf_retry_copy_block(struct ccw_device *cdev)
{
	struct copy_block_struct *copy_block = cdev->private->cmb_wait;

	if (!copy_block)
		return;

	copy_block->ret = cmf_copy_block(cdev);
	wake_up(&copy_block->wait);
}

static void cmf_generic_reset(struct ccw_device *cdev)
{
	struct cmb_data *cmb_data;

	spin_lock_irq(cdev->ccwlock);
	cmb_data = cdev->private->cmb;
	if (cmb_data) {
		memset(cmb_data->last_block, 0, cmb_data->size);
		/*
		 * Need to reset hw block as well to make the hardware start
		 * from 0 again.
		 */
		memset(cmb_data->hw_block, 0, cmb_data->size);
		cmb_data->last_update = 0;
	}
	cdev->private->cmb_start_time = get_tod_clock();
	spin_unlock_irq(cdev->ccwlock);
}

/**
 * struct cmb_area - container for global cmb data
 *
 * @mem:	pointer to CMBs (only in basic measurement mode)
 * @list:	contains a linked list of all subchannels
 * @num_channels: number of channels to be measured
 * @lock:	protect concurrent access to @mem and @list
 */
struct cmb_area {
	struct cmb *mem;
	struct list_head list;
	int num_channels;
	spinlock_t lock;
};

static struct cmb_area cmb_area = {
	.lock = __SPIN_LOCK_UNLOCKED(cmb_area.lock),
	.list = LIST_HEAD_INIT(cmb_area.list),
	.num_channels  = 1024,
};

/* ****** old style CMB handling ********/

/*
 * Basic channel measurement blocks are allocated in one contiguous
 * block of memory, which can not be moved as long as any channel
 * is active. Therefore, a maximum number of subchannels needs to
 * be defined somewhere. This is a module parameter, defaulting to
 * a reasonable value of 1024, or 32 kb of memory.
 * Current kernels don't allow kmalloc with more than 128kb, so the
 * maximum is 4096.
 */

module_param_named(maxchannels, cmb_area.num_channels, uint, 0444);

/**
 * struct cmb - basic channel measurement block
 * @ssch_rsch_count: number of ssch and rsch
 * @sample_count: number of samples
 * @device_connect_time: time of device connect
 * @function_pending_time: time of function pending
 * @device_disconnect_time: time of device disconnect
 * @control_unit_queuing_time: time of control unit queuing
 * @device_active_only_time: time of device active only
 * @reserved: unused in basic measurement mode
 *
 * The measurement block as used by the hardware. The fields are described
 * further in z/Architecture Principles of Operation, chapter 17.
 *
 * The cmb area made up from these blocks must be a contiguous array and may
 * not be reallocated or freed.
 * Only one cmb area can be present in the system.
 */
struct cmb {
	u16 ssch_rsch_count;
	u16 sample_count;
	u32 device_connect_time;
	u32 function_pending_time;
	u32 device_disconnect_time;
	u32 control_unit_queuing_time;
	u32 device_active_only_time;
	u32 reserved[2];
};

/*
 * Insert a single device into the cmb_area list.
 * Called with cmb_area.lock held from alloc_cmb.
 */
static int alloc_cmb_single(struct ccw_device *cdev,
			    struct cmb_data *cmb_data)
{
	struct cmb *cmb;
	struct ccw_device_private *node;
	int ret;

	spin_lock_irq(cdev->ccwlock);
	if (!list_empty(&cdev->private->cmb_list)) {
		ret = -EBUSY;
		goto out;
	}

	/*
	 * Find first unused cmb in cmb_area.mem.
	 * This is a little tricky: cmb_area.list
	 * remains sorted by ->cmb->hw_data pointers.
	 */
	cmb = cmb_area.mem;
	list_for_each_entry(node, &cmb_area.list, cmb_list) {
		struct cmb_data *data;
		data = node->cmb;
		if ((struct cmb*)data->hw_block > cmb)
			break;
		cmb++;
	}
	if (cmb - cmb_area.mem >= cmb_area.num_channels) {
		ret = -ENOMEM;
		goto out;
	}

	/* insert new cmb */
	list_add_tail(&cdev->private->cmb_list, &node->cmb_list);
	cmb_data->hw_block = cmb;
	cdev->private->cmb = cmb_data;
	ret = 0;
out:
	spin_unlock_irq(cdev->ccwlock);
	return ret;
}

static int alloc_cmb(struct ccw_device *cdev)
{
	int ret;
	struct cmb *mem;
	ssize_t size;
	struct cmb_data *cmb_data;

	/* Allocate private cmb_data. */
	cmb_data = kzalloc(sizeof(struct cmb_data), GFP_KERNEL);
	if (!cmb_data)
		return -ENOMEM;

	cmb_data->last_block = kzalloc(sizeof(struct cmb), GFP_KERNEL);
	if (!cmb_data->last_block) {
		kfree(cmb_data);
		return -ENOMEM;
	}
	cmb_data->size = sizeof(struct cmb);
	spin_lock(&cmb_area.lock);

	if (!cmb_area.mem) {
		/* there is no user yet, so we need a new area */
		size = sizeof(struct cmb) * cmb_area.num_channels;
		WARN_ON(!list_empty(&cmb_area.list));

		spin_unlock(&cmb_area.lock);
		mem = (void*)__get_free_pages(GFP_KERNEL | GFP_DMA,
				 get_order(size));
		spin_lock(&cmb_area.lock);

		if (cmb_area.mem) {
			/* ok, another thread was faster */
			free_pages((unsigned long)mem, get_order(size));
		} else if (!mem) {
			/* no luck */
			ret = -ENOMEM;
			goto out;
		} else {
			/* everything ok */
			memset(mem, 0, size);
			cmb_area.mem = mem;
			cmf_activate(cmb_area.mem, CMF_ON);
		}
	}

	/* do the actual allocation */
	ret = alloc_cmb_single(cdev, cmb_data);
out:
	spin_unlock(&cmb_area.lock);
	if (ret) {
		kfree(cmb_data->last_block);
		kfree(cmb_data);
	}
	return ret;
}

static void free_cmb(struct ccw_device *cdev)
{
	struct ccw_device_private *priv;
	struct cmb_data *cmb_data;

	spin_lock(&cmb_area.lock);
	spin_lock_irq(cdev->ccwlock);

	priv = cdev->private;
	cmb_data = priv->cmb;
	priv->cmb = NULL;
	if (cmb_data)
		kfree(cmb_data->last_block);
	kfree(cmb_data);
	list_del_init(&priv->cmb_list);

	if (list_empty(&cmb_area.list)) {
		ssize_t size;
		size = sizeof(struct cmb) * cmb_area.num_channels;
		cmf_activate(NULL, CMF_OFF);
		free_pages((unsigned long)cmb_area.mem, get_order(size));
		cmb_area.mem = NULL;
	}
	spin_unlock_irq(cdev->ccwlock);
	spin_unlock(&cmb_area.lock);
}

static int set_cmb(struct ccw_device *cdev, u32 mme)
{
	u16 offset;
	struct cmb_data *cmb_data;
	unsigned long flags;

	spin_lock_irqsave(cdev->ccwlock, flags);
	if (!cdev->private->cmb) {
		spin_unlock_irqrestore(cdev->ccwlock, flags);
		return -EINVAL;
	}
	cmb_data = cdev->private->cmb;
	offset = mme ? (struct cmb *)cmb_data->hw_block - cmb_area.mem : 0;
	spin_unlock_irqrestore(cdev->ccwlock, flags);

	return set_schib_wait(cdev, mme, 0, offset);
}

/* calculate utilization in 0.1 percent units */
static u64 __cmb_utilization(u64 device_connect_time, u64 function_pending_time,
			     u64 device_disconnect_time, u64 start_time)
{
	u64 utilization, elapsed_time;

	utilization = time_to_nsec(device_connect_time +
				   function_pending_time +
				   device_disconnect_time);

	elapsed_time = get_tod_clock() - start_time;
	elapsed_time = tod_to_ns(elapsed_time);
	elapsed_time /= 1000;

	return elapsed_time ? (utilization / elapsed_time) : 0;
}

static u64 read_cmb(struct ccw_device *cdev, int index)
{
	struct cmb_data *cmb_data;
	unsigned long flags;
	struct cmb *cmb;
	u64 ret = 0;
	u32 val;

	spin_lock_irqsave(cdev->ccwlock, flags);
	cmb_data = cdev->private->cmb;
	if (!cmb_data)
		goto out;

	cmb = cmb_data->hw_block;
	switch (index) {
	case avg_utilization:
		ret = __cmb_utilization(cmb->device_connect_time,
					cmb->function_pending_time,
					cmb->device_disconnect_time,
					cdev->private->cmb_start_time);
		goto out;
	case cmb_ssch_rsch_count:
		ret = cmb->ssch_rsch_count;
		goto out;
	case cmb_sample_count:
		ret = cmb->sample_count;
		goto out;
	case cmb_device_connect_time:
		val = cmb->device_connect_time;
		break;
	case cmb_function_pending_time:
		val = cmb->function_pending_time;
		break;
	case cmb_device_disconnect_time:
		val = cmb->device_disconnect_time;
		break;
	case cmb_control_unit_queuing_time:
		val = cmb->control_unit_queuing_time;
		break;
	case cmb_device_active_only_time:
		val = cmb->device_active_only_time;
		break;
	default:
		goto out;
	}
	ret = time_to_avg_nsec(val, cmb->sample_count);
out:
	spin_unlock_irqrestore(cdev->ccwlock, flags);
	return ret;
}

static int readall_cmb(struct ccw_device *cdev, struct cmbdata *data)
{
	struct cmb *cmb;
	struct cmb_data *cmb_data;
	u64 time;
	unsigned long flags;
	int ret;

	ret = cmf_cmb_copy_wait(cdev);
	if (ret < 0)
		return ret;
	spin_lock_irqsave(cdev->ccwlock, flags);
	cmb_data = cdev->private->cmb;
	if (!cmb_data) {
		ret = -ENODEV;
		goto out;
	}
	if (cmb_data->last_update == 0) {
		ret = -EAGAIN;
		goto out;
	}
	cmb = cmb_data->last_block;
	time = cmb_data->last_update - cdev->private->cmb_start_time;

	memset(data, 0, sizeof(struct cmbdata));

	/* we only know values before device_busy_time */
	data->size = offsetof(struct cmbdata, device_busy_time);

	data->elapsed_time = tod_to_ns(time);

	/* copy data to new structure */
	data->ssch_rsch_count = cmb->ssch_rsch_count;
	data->sample_count = cmb->sample_count;

	/* time fields are converted to nanoseconds while copying */
	data->device_connect_time = time_to_nsec(cmb->device_connect_time);
	data->function_pending_time = time_to_nsec(cmb->function_pending_time);
	data->device_disconnect_time =
		time_to_nsec(cmb->device_disconnect_time);
	data->control_unit_queuing_time
		= time_to_nsec(cmb->control_unit_queuing_time);
	data->device_active_only_time
		= time_to_nsec(cmb->device_active_only_time);
	ret = 0;
out:
	spin_unlock_irqrestore(cdev->ccwlock, flags);
	return ret;
}

static void reset_cmb(struct ccw_device *cdev)
{
	cmf_generic_reset(cdev);
}

static int cmf_enabled(struct ccw_device *cdev)
{
	int enabled;

	spin_lock_irq(cdev->ccwlock);
	enabled = !!cdev->private->cmb;
	spin_unlock_irq(cdev->ccwlock);

	return enabled;
}

static struct attribute_group cmf_attr_group;

static struct cmb_operations cmbops_basic = {
	.alloc	= alloc_cmb,
	.free	= free_cmb,
	.set	= set_cmb,
	.read	= read_cmb,
	.readall    = readall_cmb,
	.reset	    = reset_cmb,
	.attr_group = &cmf_attr_group,
};

/* ******** extended cmb handling ********/

/**
 * struct cmbe - extended channel measurement block
 * @ssch_rsch_count: number of ssch and rsch
 * @sample_count: number of samples
 * @device_connect_time: time of device connect
 * @function_pending_time: time of function pending
 * @device_disconnect_time: time of device disconnect
 * @control_unit_queuing_time: time of control unit queuing
 * @device_active_only_time: time of device active only
 * @device_busy_time: time of device busy
 * @initial_command_response_time: initial command response time
 * @reserved: unused
 *
 * The measurement block as used by the hardware. May be in any 64 bit physical
 * location.
 * The fields are described further in z/Architecture Principles of Operation,
 * third edition, chapter 17.
 */
struct cmbe {
	u32 ssch_rsch_count;
	u32 sample_count;
	u32 device_connect_time;
	u32 function_pending_time;
	u32 device_disconnect_time;
	u32 control_unit_queuing_time;
	u32 device_active_only_time;
	u32 device_busy_time;
	u32 initial_command_response_time;
	u32 reserved[7];
} __packed __aligned(64);

static struct kmem_cache *cmbe_cache;

static int alloc_cmbe(struct ccw_device *cdev)
{
	struct cmb_data *cmb_data;
	struct cmbe *cmbe;
	int ret = -ENOMEM;

	cmbe = kmem_cache_zalloc(cmbe_cache, GFP_KERNEL);
	if (!cmbe)
		return ret;

	cmb_data = kzalloc(sizeof(*cmb_data), GFP_KERNEL);
	if (!cmb_data)
		goto out_free;

	cmb_data->last_block = kzalloc(sizeof(struct cmbe), GFP_KERNEL);
	if (!cmb_data->last_block)
		goto out_free;

	cmb_data->size = sizeof(*cmbe);
	cmb_data->hw_block = cmbe;

	spin_lock(&cmb_area.lock);
	spin_lock_irq(cdev->ccwlock);
	if (cdev->private->cmb)
		goto out_unlock;

	cdev->private->cmb = cmb_data;

	/* activate global measurement if this is the first channel */
	if (list_empty(&cmb_area.list))
		cmf_activate(NULL, CMF_ON);
	list_add_tail(&cdev->private->cmb_list, &cmb_area.list);

	spin_unlock_irq(cdev->ccwlock);
	spin_unlock(&cmb_area.lock);
	return 0;

out_unlock:
	spin_unlock_irq(cdev->ccwlock);
	spin_unlock(&cmb_area.lock);
	ret = -EBUSY;
out_free:
	if (cmb_data)
		kfree(cmb_data->last_block);
	kfree(cmb_data);
	kmem_cache_free(cmbe_cache, cmbe);

	return ret;
}

static void free_cmbe(struct ccw_device *cdev)
{
	struct cmb_data *cmb_data;

	spin_lock(&cmb_area.lock);
	spin_lock_irq(cdev->ccwlock);
	cmb_data = cdev->private->cmb;
	cdev->private->cmb = NULL;
	if (cmb_data) {
		kfree(cmb_data->last_block);
		kmem_cache_free(cmbe_cache, cmb_data->hw_block);
	}
	kfree(cmb_data);

	/* deactivate global measurement if this is the last channel */
	list_del_init(&cdev->private->cmb_list);
	if (list_empty(&cmb_area.list))
		cmf_activate(NULL, CMF_OFF);
	spin_unlock_irq(cdev->ccwlock);
	spin_unlock(&cmb_area.lock);
}

static int set_cmbe(struct ccw_device *cdev, u32 mme)
{
	unsigned long mba;
	struct cmb_data *cmb_data;
	unsigned long flags;

	spin_lock_irqsave(cdev->ccwlock, flags);
	if (!cdev->private->cmb) {
		spin_unlock_irqrestore(cdev->ccwlock, flags);
		return -EINVAL;
	}
	cmb_data = cdev->private->cmb;
	mba = mme ? (unsigned long) cmb_data->hw_block : 0;
	spin_unlock_irqrestore(cdev->ccwlock, flags);

	return set_schib_wait(cdev, mme, 1, mba);
}

static u64 read_cmbe(struct ccw_device *cdev, int index)
{
	struct cmb_data *cmb_data;
	unsigned long flags;
	struct cmbe *cmb;
	u64 ret = 0;
	u32 val;

	spin_lock_irqsave(cdev->ccwlock, flags);
	cmb_data = cdev->private->cmb;
	if (!cmb_data)
		goto out;

	cmb = cmb_data->hw_block;
	switch (index) {
	case avg_utilization:
		ret = __cmb_utilization(cmb->device_connect_time,
					cmb->function_pending_time,
					cmb->device_disconnect_time,
					cdev->private->cmb_start_time);
		goto out;
	case cmb_ssch_rsch_count:
		ret = cmb->ssch_rsch_count;
		goto out;
	case cmb_sample_count:
		ret = cmb->sample_count;
		goto out;
	case cmb_device_connect_time:
		val = cmb->device_connect_time;
		break;
	case cmb_function_pending_time:
		val = cmb->function_pending_time;
		break;
	case cmb_device_disconnect_time:
		val = cmb->device_disconnect_time;
		break;
	case cmb_control_unit_queuing_time:
		val = cmb->control_unit_queuing_time;
		break;
	case cmb_device_active_only_time:
		val = cmb->device_active_only_time;
		break;
	case cmb_device_busy_time:
		val = cmb->device_busy_time;
		break;
	case cmb_initial_command_response_time:
		val = cmb->initial_command_response_time;
		break;
	default:
		goto out;
	}
	ret = time_to_avg_nsec(val, cmb->sample_count);
out:
	spin_unlock_irqrestore(cdev->ccwlock, flags);
	return ret;
}

static int readall_cmbe(struct ccw_device *cdev, struct cmbdata *data)
{
	struct cmbe *cmb;
	struct cmb_data *cmb_data;
	u64 time;
	unsigned long flags;
	int ret;

	ret = cmf_cmb_copy_wait(cdev);
	if (ret < 0)
		return ret;
	spin_lock_irqsave(cdev->ccwlock, flags);
	cmb_data = cdev->private->cmb;
	if (!cmb_data) {
		ret = -ENODEV;
		goto out;
	}
	if (cmb_data->last_update == 0) {
		ret = -EAGAIN;
		goto out;
	}
	time = cmb_data->last_update - cdev->private->cmb_start_time;

	memset (data, 0, sizeof(struct cmbdata));

	/* we only know values before device_busy_time */
	data->size = offsetof(struct cmbdata, device_busy_time);

	data->elapsed_time = tod_to_ns(time);

	cmb = cmb_data->last_block;
	/* copy data to new structure */
	data->ssch_rsch_count = cmb->ssch_rsch_count;
	data->sample_count = cmb->sample_count;

	/* time fields are converted to nanoseconds while copying */
	data->device_connect_time = time_to_nsec(cmb->device_connect_time);
	data->function_pending_time = time_to_nsec(cmb->function_pending_time);
	data->device_disconnect_time =
		time_to_nsec(cmb->device_disconnect_time);
	data->control_unit_queuing_time
		= time_to_nsec(cmb->control_unit_queuing_time);
	data->device_active_only_time
		= time_to_nsec(cmb->device_active_only_time);
	data->device_busy_time = time_to_nsec(cmb->device_busy_time);
	data->initial_command_response_time
		= time_to_nsec(cmb->initial_command_response_time);

	ret = 0;
out:
	spin_unlock_irqrestore(cdev->ccwlock, flags);
	return ret;
}

static void reset_cmbe(struct ccw_device *cdev)
{
	cmf_generic_reset(cdev);
}

static struct attribute_group cmf_attr_group_ext;

static struct cmb_operations cmbops_extended = {
	.alloc	    = alloc_cmbe,
	.free	    = free_cmbe,
	.set	    = set_cmbe,
	.read	    = read_cmbe,
	.readall    = readall_cmbe,
	.reset	    = reset_cmbe,
	.attr_group = &cmf_attr_group_ext,
};

static ssize_t cmb_show_attr(struct device *dev, char *buf, enum cmb_index idx)
{
	return sprintf(buf, "%lld\n",
		(unsigned long long) cmf_read(to_ccwdev(dev), idx));
}

static ssize_t cmb_show_avg_sample_interval(struct device *dev,
					    struct device_attribute *attr,
					    char *buf)
{
	struct ccw_device *cdev = to_ccwdev(dev);
	unsigned long count;
	long interval;

	count = cmf_read(cdev, cmb_sample_count);
	spin_lock_irq(cdev->ccwlock);
	if (count) {
		interval = get_tod_clock() - cdev->private->cmb_start_time;
		interval = tod_to_ns(interval);
		interval /= count;
	} else
		interval = -1;
	spin_unlock_irq(cdev->ccwlock);
	return sprintf(buf, "%ld\n", interval);
}

static ssize_t cmb_show_avg_utilization(struct device *dev,
					struct device_attribute *attr,
					char *buf)
{
	unsigned long u = cmf_read(to_ccwdev(dev), avg_utilization);

	return sprintf(buf, "%02lu.%01lu%%\n", u / 10, u % 10);
}

#define cmf_attr(name) \
static ssize_t show_##name(struct device *dev, \
			   struct device_attribute *attr, char *buf)	\
{ return cmb_show_attr((dev), buf, cmb_##name); } \
static DEVICE_ATTR(name, 0444, show_##name, NULL);

#define cmf_attr_avg(name) \
static ssize_t show_avg_##name(struct device *dev, \
			       struct device_attribute *attr, char *buf) \
{ return cmb_show_attr((dev), buf, cmb_##name); } \
static DEVICE_ATTR(avg_##name, 0444, show_avg_##name, NULL);

cmf_attr(ssch_rsch_count);
cmf_attr(sample_count);
cmf_attr_avg(device_connect_time);
cmf_attr_avg(function_pending_time);
cmf_attr_avg(device_disconnect_time);
cmf_attr_avg(control_unit_queuing_time);
cmf_attr_avg(device_active_only_time);
cmf_attr_avg(device_busy_time);
cmf_attr_avg(initial_command_response_time);

static DEVICE_ATTR(avg_sample_interval, 0444, cmb_show_avg_sample_interval,
		   NULL);
static DEVICE_ATTR(avg_utilization, 0444, cmb_show_avg_utilization, NULL);

static struct attribute *cmf_attributes[] = {
	&dev_attr_avg_sample_interval.attr,
	&dev_attr_avg_utilization.attr,
	&dev_attr_ssch_rsch_count.attr,
	&dev_attr_sample_count.attr,
	&dev_attr_avg_device_connect_time.attr,
	&dev_attr_avg_function_pending_time.attr,
	&dev_attr_avg_device_disconnect_time.attr,
	&dev_attr_avg_control_unit_queuing_time.attr,
	&dev_attr_avg_device_active_only_time.attr,
	NULL,
};

static struct attribute_group cmf_attr_group = {
	.name  = "cmf",
	.attrs = cmf_attributes,
};

static struct attribute *cmf_attributes_ext[] = {
	&dev_attr_avg_sample_interval.attr,
	&dev_attr_avg_utilization.attr,
	&dev_attr_ssch_rsch_count.attr,
	&dev_attr_sample_count.attr,
	&dev_attr_avg_device_connect_time.attr,
	&dev_attr_avg_function_pending_time.attr,
	&dev_attr_avg_device_disconnect_time.attr,
	&dev_attr_avg_control_unit_queuing_time.attr,
	&dev_attr_avg_device_active_only_time.attr,
	&dev_attr_avg_device_busy_time.attr,
	&dev_attr_avg_initial_command_response_time.attr,
	NULL,
};

static struct attribute_group cmf_attr_group_ext = {
	.name  = "cmf",
	.attrs = cmf_attributes_ext,
};

static ssize_t cmb_enable_show(struct device *dev,
			       struct device_attribute *attr,
			       char *buf)
{
	struct ccw_device *cdev = to_ccwdev(dev);

	return sprintf(buf, "%d\n", cmf_enabled(cdev));
}

static ssize_t cmb_enable_store(struct device *dev,
				struct device_attribute *attr, const char *buf,
				size_t c)
{
	struct ccw_device *cdev = to_ccwdev(dev);
	unsigned long val;
	int ret;

	ret = kstrtoul(buf, 16, &val);
	if (ret)
		return ret;

	switch (val) {
	case 0:
		ret = disable_cmf(cdev);
		break;
	case 1:
		ret = enable_cmf(cdev);
		break;
	default:
		ret = -EINVAL;
	}

	return ret ? ret : c;
}
DEVICE_ATTR_RW(cmb_enable);

/**
 * enable_cmf() - switch on the channel measurement for a specific device
 *  @cdev:	The ccw device to be enabled
 *
 *  Enable channel measurements for @cdev. If this is called on a device
 *  for which channel measurement is already enabled a reset of the
 *  measurement data is triggered.
 *  Returns: %0 for success or a negative error value.
 *  Context:
 *    non-atomic
 */
int enable_cmf(struct ccw_device *cdev)
{
	int ret = 0;

	device_lock(&cdev->dev);
	if (cmf_enabled(cdev)) {
		cmbops->reset(cdev);
		goto out_unlock;
	}
	get_device(&cdev->dev);
	ret = cmbops->alloc(cdev);
	if (ret)
		goto out;
	cmbops->reset(cdev);
	ret = sysfs_create_group(&cdev->dev.kobj, cmbops->attr_group);
	if (ret) {
		cmbops->free(cdev);
		goto out;
	}
	ret = cmbops->set(cdev, 2);
	if (ret) {
		sysfs_remove_group(&cdev->dev.kobj, cmbops->attr_group);
		cmbops->free(cdev);
	}
out:
	if (ret)
		put_device(&cdev->dev);
out_unlock:
	device_unlock(&cdev->dev);
	return ret;
}

/**
 * __disable_cmf() - switch off the channel measurement for a specific device
 *  @cdev:	The ccw device to be disabled
 *
 *  Returns: %0 for success or a negative error value.
 *
 *  Context:
 *    non-atomic, device_lock() held.
 */
int __disable_cmf(struct ccw_device *cdev)
{
	int ret;

	ret = cmbops->set(cdev, 0);
	if (ret)
		return ret;

	sysfs_remove_group(&cdev->dev.kobj, cmbops->attr_group);
	cmbops->free(cdev);
	put_device(&cdev->dev);

	return ret;
}

/**
 * disable_cmf() - switch off the channel measurement for a specific device
 *  @cdev:	The ccw device to be disabled
 *
 *  Returns: %0 for success or a negative error value.
 *
 *  Context:
 *    non-atomic
 */
int disable_cmf(struct ccw_device *cdev)
{
	int ret;

	device_lock(&cdev->dev);
	ret = __disable_cmf(cdev);
	device_unlock(&cdev->dev);

	return ret;
}

/**
 * cmf_read() - read one value from the current channel measurement block
 * @cdev:	the channel to be read
 * @index:	the index of the value to be read
 *
 * Returns: The value read or %0 if the value cannot be read.
 *
 *  Context:
 *    any
 */
u64 cmf_read(struct ccw_device *cdev, int index)
{
	return cmbops->read(cdev, index);
}

/**
 * cmf_readall() - read the current channel measurement block
 * @cdev:	the channel to be read
 * @data:	a pointer to a data block that will be filled
 *
 * Returns: %0 on success, a negative error value otherwise.
 *
 *  Context:
 *    any
 */
int cmf_readall(struct ccw_device *cdev, struct cmbdata *data)
{
	return cmbops->readall(cdev, data);
}

/* Reenable cmf when a disconnected device becomes available again. */
int cmf_reenable(struct ccw_device *cdev)
{
	cmbops->reset(cdev);
	return cmbops->set(cdev, 2);
}

/**
 * cmf_reactivate() - reactivate measurement block updates
 *
 * Use this during resume from hibernate.
 */
void cmf_reactivate(void)
{
	spin_lock(&cmb_area.lock);
	if (!list_empty(&cmb_area.list))
		cmf_activate(cmb_area.mem, CMF_ON);
	spin_unlock(&cmb_area.lock);
}

static int __init init_cmbe(void)
{
	cmbe_cache = kmem_cache_create("cmbe_cache", sizeof(struct cmbe),
				       __alignof__(struct cmbe), 0, NULL);

	return cmbe_cache ? 0 : -ENOMEM;
}

static int __init init_cmf(void)
{
	char *format_string;
	char *detect_string;
	int ret;

	/*
	 * If the user did not give a parameter, see if we are running on a
	 * machine supporting extended measurement blocks, otherwise fall back
	 * to basic mode.
	 */
	if (format == CMF_AUTODETECT) {
		if (!css_general_characteristics.ext_mb) {
			format = CMF_BASIC;
		} else {
			format = CMF_EXTENDED;
		}
		detect_string = "autodetected";
	} else {
		detect_string = "parameter";
	}

	switch (format) {
	case CMF_BASIC:
		format_string = "basic";
		cmbops = &cmbops_basic;
		break;
	case CMF_EXTENDED:
		format_string = "extended";
		cmbops = &cmbops_extended;

		ret = init_cmbe();
		if (ret)
			return ret;
		break;
	default:
		return -EINVAL;
	}
	pr_info("Channel measurement facility initialized using format "
		"%s (mode %s)\n", format_string, detect_string);
	return 0;
}
device_initcall(init_cmf);

EXPORT_SYMBOL_GPL(enable_cmf);
EXPORT_SYMBOL_GPL(disable_cmf);
EXPORT_SYMBOL_GPL(cmf_read);
EXPORT_SYMBOL_GPL(cmf_readall);