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
/*
 * Atheros CARL9170 driver
 *
 * 802.11 & command trap routines
 *
 * Copyright 2008, Johannes Berg <johannes@sipsolutions.net>
 * Copyright 2009, 2010, Christian Lamparter <chunkeey@googlemail.com>
 *
 * 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; see the file COPYING.  If not, see
 * http://www.gnu.org/licenses/.
 *
 * This file incorporates work covered by the following copyright and
 * permission notice:
 *    Copyright (c) 2007-2008 Atheros Communications, Inc.
 *
 *    Permission to use, copy, modify, and/or distribute this software for any
 *    purpose with or without fee is hereby granted, provided that the above
 *    copyright notice and this permission notice appear in all copies.
 *
 *    THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 *    WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 *    MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 *    ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 *    WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 *    ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 *    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/etherdevice.h>
#include <linux/crc32.h>
#include <net/mac80211.h>
#include "carl9170.h"
#include "hw.h"
#include "cmd.h"

static void carl9170_dbg_message(struct ar9170 *ar, const char *buf, u32 len)
{
	bool restart = false;
	enum carl9170_restart_reasons reason = CARL9170_RR_NO_REASON;

	if (len > 3) {
		if (memcmp(buf, CARL9170_ERR_MAGIC, 3) == 0) {
			ar->fw.err_counter++;
			if (ar->fw.err_counter > 3) {
				restart = true;
				reason = CARL9170_RR_TOO_MANY_FIRMWARE_ERRORS;
			}
		}

		if (memcmp(buf, CARL9170_BUG_MAGIC, 3) == 0) {
			ar->fw.bug_counter++;
			restart = true;
			reason = CARL9170_RR_FATAL_FIRMWARE_ERROR;
		}
	}

	wiphy_info(ar->hw->wiphy, "FW: %.*s\n", len, buf);

	if (restart)
		carl9170_restart(ar, reason);
}

static void carl9170_handle_ps(struct ar9170 *ar, struct carl9170_rsp *rsp)
{
	u32 ps;
	bool new_ps;

	ps = le32_to_cpu(rsp->psm.state);

	new_ps = (ps & CARL9170_PSM_COUNTER) != CARL9170_PSM_WAKE;
	if (ar->ps.state != new_ps) {
		if (!new_ps) {
			ar->ps.sleep_ms = jiffies_to_msecs(jiffies -
				ar->ps.last_action);
		}

		ar->ps.last_action = jiffies;

		ar->ps.state = new_ps;
	}
}

static int carl9170_check_sequence(struct ar9170 *ar, unsigned int seq)
{
	if (ar->cmd_seq < -1)
		return 0;

	/*
	 * Initialize Counter
	 */
	if (ar->cmd_seq < 0)
		ar->cmd_seq = seq;

	/*
	 * The sequence is strictly monotonic increasing and it never skips!
	 *
	 * Therefore we can safely assume that whenever we received an
	 * unexpected sequence we have lost some valuable data.
	 */
	if (seq != ar->cmd_seq) {
		int count;

		count = (seq - ar->cmd_seq) % ar->fw.cmd_bufs;

		wiphy_err(ar->hw->wiphy, "lost %d command responses/traps! "
			  "w:%d g:%d\n", count, ar->cmd_seq, seq);

		carl9170_restart(ar, CARL9170_RR_LOST_RSP);
		return -EIO;
	}

	ar->cmd_seq = (ar->cmd_seq + 1) % ar->fw.cmd_bufs;
	return 0;
}

static void carl9170_cmd_callback(struct ar9170 *ar, u32 len, void *buffer)
{
	/*
	 * Some commands may have a variable response length
	 * and we cannot predict the correct length in advance.
	 * So we only check if we provided enough space for the data.
	 */
	if (unlikely(ar->readlen != (len - 4))) {
		dev_warn(&ar->udev->dev, "received invalid command response:"
			 "got %d, instead of %d\n", len - 4, ar->readlen);
		print_hex_dump_bytes("carl9170 cmd:", DUMP_PREFIX_OFFSET,
			ar->cmd_buf, (ar->cmd.hdr.len + 4) & 0x3f);
		print_hex_dump_bytes("carl9170 rsp:", DUMP_PREFIX_OFFSET,
			buffer, len);
		/*
		 * Do not complete. The command times out,
		 * and we get a stack trace from there.
		 */
		carl9170_restart(ar, CARL9170_RR_INVALID_RSP);
	}

	spin_lock(&ar->cmd_lock);
	if (ar->readbuf) {
		if (len >= 4)
			memcpy(ar->readbuf, buffer + 4, len - 4);

		ar->readbuf = NULL;
	}
	complete(&ar->cmd_wait);
	spin_unlock(&ar->cmd_lock);
}

void carl9170_handle_command_response(struct ar9170 *ar, void *buf, u32 len)
{
	struct carl9170_rsp *cmd = buf;
	struct ieee80211_vif *vif;

	if ((cmd->hdr.cmd & CARL9170_RSP_FLAG) != CARL9170_RSP_FLAG) {
		if (!(cmd->hdr.cmd & CARL9170_CMD_ASYNC_FLAG))
			carl9170_cmd_callback(ar, len, buf);

		return;
	}

	if (unlikely(cmd->hdr.len != (len - 4))) {
		if (net_ratelimit()) {
			wiphy_err(ar->hw->wiphy, "FW: received over-/under"
				"sized event %x (%d, but should be %d).\n",
			       cmd->hdr.cmd, cmd->hdr.len, len - 4);

			print_hex_dump_bytes("dump:", DUMP_PREFIX_NONE,
					     buf, len);
		}

		return;
	}

	/* hardware event handlers */
	switch (cmd->hdr.cmd) {
	case CARL9170_RSP_PRETBTT:
		/* pre-TBTT event */
		rcu_read_lock();
		vif = carl9170_get_main_vif(ar);

		if (!vif) {
			rcu_read_unlock();
			break;
		}

		switch (vif->type) {
		case NL80211_IFTYPE_STATION:
			carl9170_handle_ps(ar, cmd);
			break;

		case NL80211_IFTYPE_AP:
		case NL80211_IFTYPE_ADHOC:
		case NL80211_IFTYPE_MESH_POINT:
			carl9170_update_beacon(ar, true);
			break;

		default:
			break;
		}
		rcu_read_unlock();

		break;


	case CARL9170_RSP_TXCOMP:
		/* TX status notification */
		carl9170_tx_process_status(ar, cmd);
		break;

	case CARL9170_RSP_BEACON_CONFIG:
		/*
		 * (IBSS) beacon send notification
		 * bytes: 04 c2 XX YY B4 B3 B2 B1
		 *
		 * XX always 80
		 * YY always 00
		 * B1-B4 "should" be the number of send out beacons.
		 */
		break;

	case CARL9170_RSP_ATIM:
		/* End of Atim Window */
		break;

	case CARL9170_RSP_WATCHDOG:
		/* Watchdog Interrupt */
		carl9170_restart(ar, CARL9170_RR_WATCHDOG);
		break;

	case CARL9170_RSP_TEXT:
		/* firmware debug */
		carl9170_dbg_message(ar, (char *)buf + 4, len - 4);
		break;

	case CARL9170_RSP_HEXDUMP:
		wiphy_dbg(ar->hw->wiphy, "FW: HD %d\n", len - 4);
		print_hex_dump_bytes("FW:", DUMP_PREFIX_NONE,
				     (char *)buf + 4, len - 4);
		break;

	case CARL9170_RSP_RADAR:
		if (!net_ratelimit())
			break;

		wiphy_info(ar->hw->wiphy, "FW: RADAR! Please report this "
		       "incident to linux-wireless@vger.kernel.org !\n");
		break;

	case CARL9170_RSP_GPIO:
#ifdef CONFIG_CARL9170_WPC
		if (ar->wps.pbc) {
			bool state = !!(cmd->gpio.gpio & cpu_to_le32(
				AR9170_GPIO_PORT_WPS_BUTTON_PRESSED));

			if (state != ar->wps.pbc_state) {
				ar->wps.pbc_state = state;
				input_report_key(ar->wps.pbc, KEY_WPS_BUTTON,
						 state);
				input_sync(ar->wps.pbc);
			}
		}
#endif /* CONFIG_CARL9170_WPC */
		break;

	case CARL9170_RSP_BOOT:
		complete(&ar->fw_boot_wait);
		break;

	default:
		wiphy_err(ar->hw->wiphy, "FW: received unhandled event %x\n",
			cmd->hdr.cmd);
		print_hex_dump_bytes("dump:", DUMP_PREFIX_NONE, buf, len);
		break;
	}
}

static int carl9170_rx_mac_status(struct ar9170 *ar,
	struct ar9170_rx_head *head, struct ar9170_rx_macstatus *mac,
	struct ieee80211_rx_status *status)
{
	struct ieee80211_channel *chan;
	u8 error, decrypt;

	BUILD_BUG_ON(sizeof(struct ar9170_rx_head) != 12);
	BUILD_BUG_ON(sizeof(struct ar9170_rx_macstatus) != 4);

	error = mac->error;

	if (error & AR9170_RX_ERROR_WRONG_RA) {
		if (!ar->sniffer_enabled)
			return -EINVAL;
	}

	if (error & AR9170_RX_ERROR_PLCP) {
		if (!(ar->filter_state & FIF_PLCPFAIL))
			return -EINVAL;

		status->flag |= RX_FLAG_FAILED_PLCP_CRC;
	}

	if (error & AR9170_RX_ERROR_FCS) {
		ar->tx_fcs_errors++;

		if (!(ar->filter_state & FIF_FCSFAIL))
			return -EINVAL;

		status->flag |= RX_FLAG_FAILED_FCS_CRC;
	}

	decrypt = ar9170_get_decrypt_type(mac);
	if (!(decrypt & AR9170_RX_ENC_SOFTWARE) &&
	    decrypt != AR9170_ENC_ALG_NONE) {
		if ((decrypt == AR9170_ENC_ALG_TKIP) &&
		    (error & AR9170_RX_ERROR_MMIC))
			status->flag |= RX_FLAG_MMIC_ERROR;

		status->flag |= RX_FLAG_DECRYPTED;
	}

	if (error & AR9170_RX_ERROR_DECRYPT && !ar->sniffer_enabled)
		return -ENODATA;

	error &= ~(AR9170_RX_ERROR_MMIC |
		   AR9170_RX_ERROR_FCS |
		   AR9170_RX_ERROR_WRONG_RA |
		   AR9170_RX_ERROR_DECRYPT |
		   AR9170_RX_ERROR_PLCP);

	/* drop any other error frames */
	if (unlikely(error)) {
		/* TODO: update netdevice's RX dropped/errors statistics */

		if (net_ratelimit())
			wiphy_dbg(ar->hw->wiphy, "received frame with "
			       "suspicious error code (%#x).\n", error);

		return -EINVAL;
	}

	chan = ar->channel;
	if (chan) {
		status->band = chan->band;
		status->freq = chan->center_freq;
	}

	switch (mac->status & AR9170_RX_STATUS_MODULATION) {
	case AR9170_RX_STATUS_MODULATION_CCK:
		if (mac->status & AR9170_RX_STATUS_SHORT_PREAMBLE)
			status->flag |= RX_FLAG_SHORTPRE;
		switch (head->plcp[0]) {
		case AR9170_RX_PHY_RATE_CCK_1M:
			status->rate_idx = 0;
			break;
		case AR9170_RX_PHY_RATE_CCK_2M:
			status->rate_idx = 1;
			break;
		case AR9170_RX_PHY_RATE_CCK_5M:
			status->rate_idx = 2;
			break;
		case AR9170_RX_PHY_RATE_CCK_11M:
			status->rate_idx = 3;
			break;
		default:
			if (net_ratelimit()) {
				wiphy_err(ar->hw->wiphy, "invalid plcp cck "
				       "rate (%x).\n", head->plcp[0]);
			}

			return -EINVAL;
		}
		break;

	case AR9170_RX_STATUS_MODULATION_DUPOFDM:
	case AR9170_RX_STATUS_MODULATION_OFDM:
		switch (head->plcp[0] & 0xf) {
		case AR9170_TXRX_PHY_RATE_OFDM_6M:
			status->rate_idx = 0;
			break;
		case AR9170_TXRX_PHY_RATE_OFDM_9M:
			status->rate_idx = 1;
			break;
		case AR9170_TXRX_PHY_RATE_OFDM_12M:
			status->rate_idx = 2;
			break;
		case AR9170_TXRX_PHY_RATE_OFDM_18M:
			status->rate_idx = 3;
			break;
		case AR9170_TXRX_PHY_RATE_OFDM_24M:
			status->rate_idx = 4;
			break;
		case AR9170_TXRX_PHY_RATE_OFDM_36M:
			status->rate_idx = 5;
			break;
		case AR9170_TXRX_PHY_RATE_OFDM_48M:
			status->rate_idx = 6;
			break;
		case AR9170_TXRX_PHY_RATE_OFDM_54M:
			status->rate_idx = 7;
			break;
		default:
			if (net_ratelimit()) {
				wiphy_err(ar->hw->wiphy, "invalid plcp ofdm "
					"rate (%x).\n", head->plcp[0]);
			}

			return -EINVAL;
		}
		if (status->band == IEEE80211_BAND_2GHZ)
			status->rate_idx += 4;
		break;

	case AR9170_RX_STATUS_MODULATION_HT:
		if (head->plcp[3] & 0x80)
			status->flag |= RX_FLAG_40MHZ;
		if (head->plcp[6] & 0x80)
			status->flag |= RX_FLAG_SHORT_GI;

		status->rate_idx = clamp(0, 75, head->plcp[3] & 0x7f);
		status->flag |= RX_FLAG_HT;
		break;

	default:
		BUG();
		return -ENOSYS;
	}

	return 0;
}

static void carl9170_rx_phy_status(struct ar9170 *ar,
	struct ar9170_rx_phystatus *phy, struct ieee80211_rx_status *status)
{
	int i;

	BUILD_BUG_ON(sizeof(struct ar9170_rx_phystatus) != 20);

	for (i = 0; i < 3; i++)
		if (phy->rssi[i] != 0x80)
			status->antenna |= BIT(i);

	/* post-process RSSI */
	for (i = 0; i < 7; i++)
		if (phy->rssi[i] & 0x80)
			phy->rssi[i] = ((phy->rssi[i] & 0x7f) + 1) & 0x7f;

	/* TODO: we could do something with phy_errors */
	status->signal = ar->noise[0] + phy->rssi_combined;
}

static struct sk_buff *carl9170_rx_copy_data(u8 *buf, int len)
{
	struct sk_buff *skb;
	int reserved = 0;
	struct ieee80211_hdr *hdr = (void *) buf;

	if (ieee80211_is_data_qos(hdr->frame_control)) {
		u8 *qc = ieee80211_get_qos_ctl(hdr);
		reserved += NET_IP_ALIGN;

		if (*qc & IEEE80211_QOS_CTL_A_MSDU_PRESENT)
			reserved += NET_IP_ALIGN;
	}

	if (ieee80211_has_a4(hdr->frame_control))
		reserved += NET_IP_ALIGN;

	reserved = 32 + (reserved & NET_IP_ALIGN);

	skb = dev_alloc_skb(len + reserved);
	if (likely(skb)) {
		skb_reserve(skb, reserved);
		memcpy(skb_put(skb, len), buf, len);
	}

	return skb;
}

static u8 *carl9170_find_ie(u8 *data, unsigned int len, u8 ie)
{
	struct ieee80211_mgmt *mgmt = (void *)data;
	u8 *pos, *end;

	pos = (u8 *)mgmt->u.beacon.variable;
	end = data + len;
	while (pos < end) {
		if (pos + 2 + pos[1] > end)
			return NULL;

		if (pos[0] == ie)
			return pos;

		pos += 2 + pos[1];
	}
	return NULL;
}

/*
 * NOTE:
 *
 * The firmware is in charge of waking up the device just before
 * the AP is expected to transmit the next beacon.
 *
 * This leaves the driver with the important task of deciding when
 * to set the PHY back to bed again.
 */
static void carl9170_ps_beacon(struct ar9170 *ar, void *data, unsigned int len)
{
	struct ieee80211_hdr *hdr = data;
	struct ieee80211_tim_ie *tim_ie;
	u8 *tim;
	u8 tim_len;
	bool cam;

	if (likely(!(ar->hw->conf.flags & IEEE80211_CONF_PS)))
		return;

	/* check if this really is a beacon */
	if (!ieee80211_is_beacon(hdr->frame_control))
		return;

	/* min. beacon length + FCS_LEN */
	if (len <= 40 + FCS_LEN)
		return;

	/* and only beacons from the associated BSSID, please */
	if (!ether_addr_equal(hdr->addr3, ar->common.curbssid) ||
	    !ar->common.curaid)
		return;

	ar->ps.last_beacon = jiffies;

	tim = carl9170_find_ie(data, len - FCS_LEN, WLAN_EID_TIM);
	if (!tim)
		return;

	if (tim[1] < sizeof(*tim_ie))
		return;

	tim_len = tim[1];
	tim_ie = (struct ieee80211_tim_ie *) &tim[2];

	if (!WARN_ON_ONCE(!ar->hw->conf.ps_dtim_period))
		ar->ps.dtim_counter = (tim_ie->dtim_count - 1) %
			ar->hw->conf.ps_dtim_period;

	/* Check whenever the PHY can be turned off again. */

	/* 1. What about buffered unicast traffic for our AID? */
	cam = ieee80211_check_tim(tim_ie, tim_len, ar->common.curaid);

	/* 2. Maybe the AP wants to send multicast/broadcast data? */
	cam |= !!(tim_ie->bitmap_ctrl & 0x01);

	if (!cam) {
		/* back to low-power land. */
		ar->ps.off_override &= ~PS_OFF_BCN;
		carl9170_ps_check(ar);
	} else {
		/* force CAM */
		ar->ps.off_override |= PS_OFF_BCN;
	}
}

static void carl9170_ba_check(struct ar9170 *ar, void *data, unsigned int len)
{
	struct ieee80211_bar *bar = (void *) data;
	struct carl9170_bar_list_entry *entry;
	unsigned int queue;

	if (likely(!ieee80211_is_back(bar->frame_control)))
		return;

	if (len <= sizeof(*bar) + FCS_LEN)
		return;

	queue = TID_TO_WME_AC(((le16_to_cpu(bar->control) &
		IEEE80211_BAR_CTRL_TID_INFO_MASK) >>
		IEEE80211_BAR_CTRL_TID_INFO_SHIFT) & 7);

	rcu_read_lock();
	list_for_each_entry_rcu(entry, &ar->bar_list[queue], list) {
		struct sk_buff *entry_skb = entry->skb;
		struct _carl9170_tx_superframe *super = (void *)entry_skb->data;
		struct ieee80211_bar *entry_bar = (void *)super->frame_data;

#define TID_CHECK(a, b) (						\
	((a) & cpu_to_le16(IEEE80211_BAR_CTRL_TID_INFO_MASK)) ==	\
	((b) & cpu_to_le16(IEEE80211_BAR_CTRL_TID_INFO_MASK)))		\

		if (bar->start_seq_num == entry_bar->start_seq_num &&
		    TID_CHECK(bar->control, entry_bar->control) &&
		    compare_ether_addr(bar->ra, entry_bar->ta) == 0 &&
		    compare_ether_addr(bar->ta, entry_bar->ra) == 0) {
			struct ieee80211_tx_info *tx_info;

			tx_info = IEEE80211_SKB_CB(entry_skb);
			tx_info->flags |= IEEE80211_TX_STAT_ACK;

			spin_lock_bh(&ar->bar_list_lock[queue]);
			list_del_rcu(&entry->list);
			spin_unlock_bh(&ar->bar_list_lock[queue]);
			kfree_rcu(entry, head);
			break;
		}
	}
	rcu_read_unlock();

#undef TID_CHECK
}

static bool carl9170_ampdu_check(struct ar9170 *ar, u8 *buf, u8 ms,
				 struct ieee80211_rx_status *rx_status)
{
	__le16 fc;

	if ((ms & AR9170_RX_STATUS_MPDU) == AR9170_RX_STATUS_MPDU_SINGLE) {
		/*
		 * This frame is not part of an aMPDU.
		 * Therefore it is not subjected to any
		 * of the following content restrictions.
		 */
		return true;
	}

	rx_status->flag |= RX_FLAG_AMPDU_DETAILS | RX_FLAG_AMPDU_LAST_KNOWN;
	rx_status->ampdu_reference = ar->ampdu_ref;

	/*
	 * "802.11n - 7.4a.3 A-MPDU contents" describes in which contexts
	 * certain frame types can be part of an aMPDU.
	 *
	 * In order to keep the processing cost down, I opted for a
	 * stateless filter solely based on the frame control field.
	 */

	fc = ((struct ieee80211_hdr *)buf)->frame_control;
	if (ieee80211_is_data_qos(fc) && ieee80211_is_data_present(fc))
		return true;

	if (ieee80211_is_ack(fc) || ieee80211_is_back(fc) ||
	    ieee80211_is_back_req(fc))
		return true;

	if (ieee80211_is_action(fc))
		return true;

	return false;
}

static int carl9170_handle_mpdu(struct ar9170 *ar, u8 *buf, int len,
				struct ieee80211_rx_status *status)
{
	struct sk_buff *skb;

	/* (driver) frame trap handler
	 *
	 * Because power-saving mode handing has to be implemented by
	 * the driver/firmware. We have to check each incoming beacon
	 * from the associated AP, if there's new data for us (either
	 * broadcast/multicast or unicast) we have to react quickly.
	 *
	 * So, if you have you want to add additional frame trap
	 * handlers, this would be the perfect place!
	 */

	carl9170_ps_beacon(ar, buf, len);

	carl9170_ba_check(ar, buf, len);

	skb = carl9170_rx_copy_data(buf, len);
	if (!skb)
		return -ENOMEM;

	memcpy(IEEE80211_SKB_RXCB(skb), status, sizeof(*status));
	ieee80211_rx(ar->hw, skb);
	return 0;
}

/*
 * If the frame alignment is right (or the kernel has
 * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS), and there
 * is only a single MPDU in the USB frame, then we could
 * submit to mac80211 the SKB directly. However, since
 * there may be multiple packets in one SKB in stream
 * mode, and we need to observe the proper ordering,
 * this is non-trivial.
 */
static void carl9170_rx_untie_data(struct ar9170 *ar, u8 *buf, int len)
{
	struct ar9170_rx_head *head;
	struct ar9170_rx_macstatus *mac;
	struct ar9170_rx_phystatus *phy = NULL;
	struct ieee80211_rx_status status;
	int mpdu_len;
	u8 mac_status;

	if (!IS_STARTED(ar))
		return;

	if (unlikely(len < sizeof(*mac)))
		goto drop;

	memset(&status, 0, sizeof(status));

	mpdu_len = len - sizeof(*mac);

	mac = (void *)(buf + mpdu_len);
	mac_status = mac->status;
	switch (mac_status & AR9170_RX_STATUS_MPDU) {
	case AR9170_RX_STATUS_MPDU_FIRST:
		ar->ampdu_ref++;
		/* Aggregated MPDUs start with an PLCP header */
		if (likely(mpdu_len >= sizeof(struct ar9170_rx_head))) {
			head = (void *) buf;

			/*
			 * The PLCP header needs to be cached for the
			 * following MIDDLE + LAST A-MPDU packets.
			 *
			 * So, if you are wondering why all frames seem
			 * to share a common RX status information,
			 * then you have the answer right here...
			 */
			memcpy(&ar->rx_plcp, (void *) buf,
			       sizeof(struct ar9170_rx_head));

			mpdu_len -= sizeof(struct ar9170_rx_head);
			buf += sizeof(struct ar9170_rx_head);

			ar->rx_has_plcp = true;
		} else {
			if (net_ratelimit()) {
				wiphy_err(ar->hw->wiphy, "plcp info "
					"is clipped.\n");
			}

			goto drop;
		}
		break;

	case AR9170_RX_STATUS_MPDU_LAST:
		status.flag |= RX_FLAG_AMPDU_IS_LAST;

		/*
		 * The last frame of an A-MPDU has an extra tail
		 * which does contain the phy status of the whole
		 * aggregate.
		 */
		if (likely(mpdu_len >= sizeof(struct ar9170_rx_phystatus))) {
			mpdu_len -= sizeof(struct ar9170_rx_phystatus);
			phy = (void *)(buf + mpdu_len);
		} else {
			if (net_ratelimit()) {
				wiphy_err(ar->hw->wiphy, "frame tail "
					"is clipped.\n");
			}

			goto drop;
		}

	case AR9170_RX_STATUS_MPDU_MIDDLE:
		/*  These are just data + mac status */
		if (unlikely(!ar->rx_has_plcp)) {
			if (!net_ratelimit())
				return;

			wiphy_err(ar->hw->wiphy, "rx stream does not start "
					"with a first_mpdu frame tag.\n");

			goto drop;
		}

		head = &ar->rx_plcp;
		break;

	case AR9170_RX_STATUS_MPDU_SINGLE:
		/* single mpdu has both: plcp (head) and phy status (tail) */
		head = (void *) buf;

		mpdu_len -= sizeof(struct ar9170_rx_head);
		mpdu_len -= sizeof(struct ar9170_rx_phystatus);

		buf += sizeof(struct ar9170_rx_head);
		phy = (void *)(buf + mpdu_len);
		break;

	default:
		BUG_ON(1);
		break;
	}

	/* FC + DU + RA + FCS */
	if (unlikely(mpdu_len < (2 + 2 + ETH_ALEN + FCS_LEN)))
		goto drop;

	if (unlikely(carl9170_rx_mac_status(ar, head, mac, &status)))
		goto drop;

	if (!carl9170_ampdu_check(ar, buf, mac_status, &status))
		goto drop;

	if (phy)
		carl9170_rx_phy_status(ar, phy, &status);
	else
		status.flag |= RX_FLAG_NO_SIGNAL_VAL;

	if (carl9170_handle_mpdu(ar, buf, mpdu_len, &status))
		goto drop;

	return;
drop:
	ar->rx_dropped++;
}

static void carl9170_rx_untie_cmds(struct ar9170 *ar, const u8 *respbuf,
				   const unsigned int resplen)
{
	struct carl9170_rsp *cmd;
	int i = 0;

	while (i < resplen) {
		cmd = (void *) &respbuf[i];

		i += cmd->hdr.len + 4;
		if (unlikely(i > resplen))
			break;

		if (carl9170_check_sequence(ar, cmd->hdr.seq))
			break;

		carl9170_handle_command_response(ar, cmd, cmd->hdr.len + 4);
	}

	if (unlikely(i != resplen)) {
		if (!net_ratelimit())
			return;

		wiphy_err(ar->hw->wiphy, "malformed firmware trap:\n");
		print_hex_dump_bytes("rxcmd:", DUMP_PREFIX_OFFSET,
				     respbuf, resplen);
	}
}

static void __carl9170_rx(struct ar9170 *ar, u8 *buf, unsigned int len)
{
	unsigned int i = 0;

	/* weird thing, but this is the same in the original driver */
	while (len > 2 && i < 12 && buf[0] == 0xff && buf[1] == 0xff) {
		i += 2;
		len -= 2;
		buf += 2;
	}

	if (unlikely(len < 4))
		return;

	/* found the 6 * 0xffff marker? */
	if (i == 12)
		carl9170_rx_untie_cmds(ar, buf, len);
	else
		carl9170_rx_untie_data(ar, buf, len);
}

static void carl9170_rx_stream(struct ar9170 *ar, void *buf, unsigned int len)
{
	unsigned int tlen, wlen = 0, clen = 0;
	struct ar9170_stream *rx_stream;
	u8 *tbuf;

	tbuf = buf;
	tlen = len;

	while (tlen >= 4) {
		rx_stream = (void *) tbuf;
		clen = le16_to_cpu(rx_stream->length);
		wlen = ALIGN(clen, 4);

		/* check if this is stream has a valid tag.*/
		if (rx_stream->tag != cpu_to_le16(AR9170_RX_STREAM_TAG)) {
			/*
			 * TODO: handle the highly unlikely event that the
			 * corrupted stream has the TAG at the right position.
			 */

			/* check if the frame can be repaired. */
			if (!ar->rx_failover_missing) {

				/* this is not "short read". */
				if (net_ratelimit()) {
					wiphy_err(ar->hw->wiphy,
						"missing tag!\n");
				}

				__carl9170_rx(ar, tbuf, tlen);
				return;
			}

			if (ar->rx_failover_missing > tlen) {
				if (net_ratelimit()) {
					wiphy_err(ar->hw->wiphy,
						"possible multi "
						"stream corruption!\n");
					goto err_telluser;
				} else {
					goto err_silent;
				}
			}

			memcpy(skb_put(ar->rx_failover, tlen), tbuf, tlen);
			ar->rx_failover_missing -= tlen;

			if (ar->rx_failover_missing <= 0) {
				/*
				 * nested carl9170_rx_stream call!
				 *
				 * termination is guaranteed, even when the
				 * combined frame also have an element with
				 * a bad tag.
				 */

				ar->rx_failover_missing = 0;
				carl9170_rx_stream(ar, ar->rx_failover->data,
						   ar->rx_failover->len);

				skb_reset_tail_pointer(ar->rx_failover);
				skb_trim(ar->rx_failover, 0);
			}

			return;
		}

		/* check if stream is clipped */
		if (wlen > tlen - 4) {
			if (ar->rx_failover_missing) {
				/* TODO: handle double stream corruption. */
				if (net_ratelimit()) {
					wiphy_err(ar->hw->wiphy, "double rx "
						"stream corruption!\n");
					goto err_telluser;
				} else {
					goto err_silent;
				}
			}

			/*
			 * save incomplete data set.
			 * the firmware will resend the missing bits when
			 * the rx - descriptor comes round again.
			 */

			memcpy(skb_put(ar->rx_failover, tlen), tbuf, tlen);
			ar->rx_failover_missing = clen - tlen;
			return;
		}
		__carl9170_rx(ar, rx_stream->payload, clen);

		tbuf += wlen + 4;
		tlen -= wlen + 4;
	}

	if (tlen) {
		if (net_ratelimit()) {
			wiphy_err(ar->hw->wiphy, "%d bytes of unprocessed "
				"data left in rx stream!\n", tlen);
		}

		goto err_telluser;
	}

	return;

err_telluser:
	wiphy_err(ar->hw->wiphy, "damaged RX stream data [want:%d, "
		"data:%d, rx:%d, pending:%d ]\n", clen, wlen, tlen,
		ar->rx_failover_missing);

	if (ar->rx_failover_missing)
		print_hex_dump_bytes("rxbuf:", DUMP_PREFIX_OFFSET,
				     ar->rx_failover->data,
				     ar->rx_failover->len);

	print_hex_dump_bytes("stream:", DUMP_PREFIX_OFFSET,
			     buf, len);

	wiphy_err(ar->hw->wiphy, "please check your hardware and cables, if "
		"you see this message frequently.\n");

err_silent:
	if (ar->rx_failover_missing) {
		skb_reset_tail_pointer(ar->rx_failover);
		skb_trim(ar->rx_failover, 0);
		ar->rx_failover_missing = 0;
	}
}

void carl9170_rx(struct ar9170 *ar, void *buf, unsigned int len)
{
	if (ar->fw.rx_stream)
		carl9170_rx_stream(ar, buf, len);
	else
		__carl9170_rx(ar, buf, len);
}