linux/drivers/bluetooth/hci_h5.c
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   1/*
   2 *
   3 *  Bluetooth HCI Three-wire UART driver
   4 *
   5 *  Copyright (C) 2012  Intel Corporation
   6 *
   7 *
   8 *  This program is free software; you can redistribute it and/or modify
   9 *  it under the terms of the GNU General Public License as published by
  10 *  the Free Software Foundation; either version 2 of the License, or
  11 *  (at your option) any later version.
  12 *
  13 *  This program is distributed in the hope that it will be useful,
  14 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 *  GNU General Public License for more details.
  17 *
  18 *  You should have received a copy of the GNU General Public License
  19 *  along with this program; if not, write to the Free Software
  20 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21 *
  22 */
  23
  24#include <linux/kernel.h>
  25#include <linux/errno.h>
  26#include <linux/skbuff.h>
  27
  28#include <net/bluetooth/bluetooth.h>
  29#include <net/bluetooth/hci_core.h>
  30
  31#include "hci_uart.h"
  32
  33#define HCI_3WIRE_ACK_PKT       0
  34#define HCI_3WIRE_LINK_PKT      15
  35
  36/* Sliding window size */
  37#define H5_TX_WIN_MAX           4
  38
  39#define H5_ACK_TIMEOUT  msecs_to_jiffies(250)
  40#define H5_SYNC_TIMEOUT msecs_to_jiffies(100)
  41
  42/*
  43 * Maximum Three-wire packet:
  44 *     4 byte header + max value for 12-bit length + 2 bytes for CRC
  45 */
  46#define H5_MAX_LEN (4 + 0xfff + 2)
  47
  48/* Convenience macros for reading Three-wire header values */
  49#define H5_HDR_SEQ(hdr)         ((hdr)[0] & 0x07)
  50#define H5_HDR_ACK(hdr)         (((hdr)[0] >> 3) & 0x07)
  51#define H5_HDR_CRC(hdr)         (((hdr)[0] >> 6) & 0x01)
  52#define H5_HDR_RELIABLE(hdr)    (((hdr)[0] >> 7) & 0x01)
  53#define H5_HDR_PKT_TYPE(hdr)    ((hdr)[1] & 0x0f)
  54#define H5_HDR_LEN(hdr)         ((((hdr)[1] >> 4) & 0xff) + ((hdr)[2] << 4))
  55
  56#define SLIP_DELIMITER  0xc0
  57#define SLIP_ESC        0xdb
  58#define SLIP_ESC_DELIM  0xdc
  59#define SLIP_ESC_ESC    0xdd
  60
  61/* H5 state flags */
  62enum {
  63        H5_RX_ESC,      /* SLIP escape mode */
  64        H5_TX_ACK_REQ,  /* Pending ack to send */
  65};
  66
  67struct h5 {
  68        struct sk_buff_head     unack;          /* Unack'ed packets queue */
  69        struct sk_buff_head     rel;            /* Reliable packets queue */
  70        struct sk_buff_head     unrel;          /* Unreliable packets queue */
  71
  72        unsigned long           flags;
  73
  74        struct sk_buff          *rx_skb;        /* Receive buffer */
  75        size_t                  rx_pending;     /* Expecting more bytes */
  76        u8                      rx_ack;         /* Last ack number received */
  77
  78        int                     (*rx_func) (struct hci_uart *hu, u8 c);
  79
  80        struct timer_list       timer;          /* Retransmission timer */
  81
  82        u8                      tx_seq;         /* Next seq number to send */
  83        u8                      tx_ack;         /* Next ack number to send */
  84        u8                      tx_win;         /* Sliding window size */
  85
  86        enum {
  87                H5_UNINITIALIZED,
  88                H5_INITIALIZED,
  89                H5_ACTIVE,
  90        } state;
  91
  92        enum {
  93                H5_AWAKE,
  94                H5_SLEEPING,
  95                H5_WAKING_UP,
  96        } sleep;
  97};
  98
  99static void h5_reset_rx(struct h5 *h5);
 100
 101static void h5_link_control(struct hci_uart *hu, const void *data, size_t len)
 102{
 103        struct h5 *h5 = hu->priv;
 104        struct sk_buff *nskb;
 105
 106        nskb = alloc_skb(3, GFP_ATOMIC);
 107        if (!nskb)
 108                return;
 109
 110        bt_cb(nskb)->pkt_type = HCI_3WIRE_LINK_PKT;
 111
 112        memcpy(skb_put(nskb, len), data, len);
 113
 114        skb_queue_tail(&h5->unrel, nskb);
 115}
 116
 117static u8 h5_cfg_field(struct h5 *h5)
 118{
 119        u8 field = 0;
 120
 121        /* Sliding window size (first 3 bits) */
 122        field |= (h5->tx_win & 7);
 123
 124        return field;
 125}
 126
 127static void h5_timed_event(unsigned long arg)
 128{
 129        const unsigned char sync_req[] = { 0x01, 0x7e };
 130        unsigned char conf_req[] = { 0x03, 0xfc, 0x01 };
 131        struct hci_uart *hu = (struct hci_uart *) arg;
 132        struct h5 *h5 = hu->priv;
 133        struct sk_buff *skb;
 134        unsigned long flags;
 135
 136        BT_DBG("%s", hu->hdev->name);
 137
 138        if (h5->state == H5_UNINITIALIZED)
 139                h5_link_control(hu, sync_req, sizeof(sync_req));
 140
 141        if (h5->state == H5_INITIALIZED) {
 142                conf_req[2] = h5_cfg_field(h5);
 143                h5_link_control(hu, conf_req, sizeof(conf_req));
 144        }
 145
 146        if (h5->state != H5_ACTIVE) {
 147                mod_timer(&h5->timer, jiffies + H5_SYNC_TIMEOUT);
 148                goto wakeup;
 149        }
 150
 151        if (h5->sleep != H5_AWAKE) {
 152                h5->sleep = H5_SLEEPING;
 153                goto wakeup;
 154        }
 155
 156        BT_DBG("hu %p retransmitting %u pkts", hu, h5->unack.qlen);
 157
 158        spin_lock_irqsave_nested(&h5->unack.lock, flags, SINGLE_DEPTH_NESTING);
 159
 160        while ((skb = __skb_dequeue_tail(&h5->unack)) != NULL) {
 161                h5->tx_seq = (h5->tx_seq - 1) & 0x07;
 162                skb_queue_head(&h5->rel, skb);
 163        }
 164
 165        spin_unlock_irqrestore(&h5->unack.lock, flags);
 166
 167wakeup:
 168        hci_uart_tx_wakeup(hu);
 169}
 170
 171static int h5_open(struct hci_uart *hu)
 172{
 173        struct h5 *h5;
 174        const unsigned char sync[] = { 0x01, 0x7e };
 175
 176        BT_DBG("hu %p", hu);
 177
 178        h5 = kzalloc(sizeof(*h5), GFP_KERNEL);
 179        if (!h5)
 180                return -ENOMEM;
 181
 182        hu->priv = h5;
 183
 184        skb_queue_head_init(&h5->unack);
 185        skb_queue_head_init(&h5->rel);
 186        skb_queue_head_init(&h5->unrel);
 187
 188        h5_reset_rx(h5);
 189
 190        init_timer(&h5->timer);
 191        h5->timer.function = h5_timed_event;
 192        h5->timer.data = (unsigned long) hu;
 193
 194        h5->tx_win = H5_TX_WIN_MAX;
 195
 196        set_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags);
 197
 198        /* Send initial sync request */
 199        h5_link_control(hu, sync, sizeof(sync));
 200        mod_timer(&h5->timer, jiffies + H5_SYNC_TIMEOUT);
 201
 202        return 0;
 203}
 204
 205static int h5_close(struct hci_uart *hu)
 206{
 207        struct h5 *h5 = hu->priv;
 208
 209        skb_queue_purge(&h5->unack);
 210        skb_queue_purge(&h5->rel);
 211        skb_queue_purge(&h5->unrel);
 212
 213        del_timer(&h5->timer);
 214
 215        kfree(h5);
 216
 217        return 0;
 218}
 219
 220static void h5_pkt_cull(struct h5 *h5)
 221{
 222        struct sk_buff *skb, *tmp;
 223        unsigned long flags;
 224        int i, to_remove;
 225        u8 seq;
 226
 227        spin_lock_irqsave(&h5->unack.lock, flags);
 228
 229        to_remove = skb_queue_len(&h5->unack);
 230        if (to_remove == 0)
 231                goto unlock;
 232
 233        seq = h5->tx_seq;
 234
 235        while (to_remove > 0) {
 236                if (h5->rx_ack == seq)
 237                        break;
 238
 239                to_remove--;
 240                seq = (seq - 1) % 8;
 241        }
 242
 243        if (seq != h5->rx_ack)
 244                BT_ERR("Controller acked invalid packet");
 245
 246        i = 0;
 247        skb_queue_walk_safe(&h5->unack, skb, tmp) {
 248                if (i++ >= to_remove)
 249                        break;
 250
 251                __skb_unlink(skb, &h5->unack);
 252                kfree_skb(skb);
 253        }
 254
 255        if (skb_queue_empty(&h5->unack))
 256                del_timer(&h5->timer);
 257
 258unlock:
 259        spin_unlock_irqrestore(&h5->unack.lock, flags);
 260}
 261
 262static void h5_handle_internal_rx(struct hci_uart *hu)
 263{
 264        struct h5 *h5 = hu->priv;
 265        const unsigned char sync_req[] = { 0x01, 0x7e };
 266        const unsigned char sync_rsp[] = { 0x02, 0x7d };
 267        unsigned char conf_req[] = { 0x03, 0xfc, 0x01 };
 268        const unsigned char conf_rsp[] = { 0x04, 0x7b };
 269        const unsigned char wakeup_req[] = { 0x05, 0xfa };
 270        const unsigned char woken_req[] = { 0x06, 0xf9 };
 271        const unsigned char sleep_req[] = { 0x07, 0x78 };
 272        const unsigned char *hdr = h5->rx_skb->data;
 273        const unsigned char *data = &h5->rx_skb->data[4];
 274
 275        BT_DBG("%s", hu->hdev->name);
 276
 277        if (H5_HDR_PKT_TYPE(hdr) != HCI_3WIRE_LINK_PKT)
 278                return;
 279
 280        if (H5_HDR_LEN(hdr) < 2)
 281                return;
 282
 283        conf_req[2] = h5_cfg_field(h5);
 284
 285        if (memcmp(data, sync_req, 2) == 0) {
 286                h5_link_control(hu, sync_rsp, 2);
 287        } else if (memcmp(data, sync_rsp, 2) == 0) {
 288                h5->state = H5_INITIALIZED;
 289                h5_link_control(hu, conf_req, 3);
 290        } else if (memcmp(data, conf_req, 2) == 0) {
 291                h5_link_control(hu, conf_rsp, 2);
 292                h5_link_control(hu, conf_req, 3);
 293        } else if (memcmp(data, conf_rsp, 2) == 0) {
 294                if (H5_HDR_LEN(hdr) > 2)
 295                        h5->tx_win = (data[2] & 7);
 296                BT_DBG("Three-wire init complete. tx_win %u", h5->tx_win);
 297                h5->state = H5_ACTIVE;
 298                hci_uart_init_ready(hu);
 299                return;
 300        } else if (memcmp(data, sleep_req, 2) == 0) {
 301                BT_DBG("Peer went to sleep");
 302                h5->sleep = H5_SLEEPING;
 303                return;
 304        } else if (memcmp(data, woken_req, 2) == 0) {
 305                BT_DBG("Peer woke up");
 306                h5->sleep = H5_AWAKE;
 307        } else if (memcmp(data, wakeup_req, 2) == 0) {
 308                BT_DBG("Peer requested wakeup");
 309                h5_link_control(hu, woken_req, 2);
 310                h5->sleep = H5_AWAKE;
 311        } else {
 312                BT_DBG("Link Control: 0x%02hhx 0x%02hhx", data[0], data[1]);
 313                return;
 314        }
 315
 316        hci_uart_tx_wakeup(hu);
 317}
 318
 319static void h5_complete_rx_pkt(struct hci_uart *hu)
 320{
 321        struct h5 *h5 = hu->priv;
 322        const unsigned char *hdr = h5->rx_skb->data;
 323
 324        if (H5_HDR_RELIABLE(hdr)) {
 325                h5->tx_ack = (h5->tx_ack + 1) % 8;
 326                set_bit(H5_TX_ACK_REQ, &h5->flags);
 327                hci_uart_tx_wakeup(hu);
 328        }
 329
 330        h5->rx_ack = H5_HDR_ACK(hdr);
 331
 332        h5_pkt_cull(h5);
 333
 334        switch (H5_HDR_PKT_TYPE(hdr)) {
 335        case HCI_EVENT_PKT:
 336        case HCI_ACLDATA_PKT:
 337        case HCI_SCODATA_PKT:
 338                bt_cb(h5->rx_skb)->pkt_type = H5_HDR_PKT_TYPE(hdr);
 339
 340                /* Remove Three-wire header */
 341                skb_pull(h5->rx_skb, 4);
 342
 343                hci_recv_frame(h5->rx_skb);
 344                h5->rx_skb = NULL;
 345
 346                break;
 347
 348        default:
 349                h5_handle_internal_rx(hu);
 350                break;
 351        }
 352
 353        h5_reset_rx(h5);
 354}
 355
 356static int h5_rx_crc(struct hci_uart *hu, unsigned char c)
 357{
 358        struct h5 *h5 = hu->priv;
 359
 360        h5_complete_rx_pkt(hu);
 361        h5_reset_rx(h5);
 362
 363        return 0;
 364}
 365
 366static int h5_rx_payload(struct hci_uart *hu, unsigned char c)
 367{
 368        struct h5 *h5 = hu->priv;
 369        const unsigned char *hdr = h5->rx_skb->data;
 370
 371        if (H5_HDR_CRC(hdr)) {
 372                h5->rx_func = h5_rx_crc;
 373                h5->rx_pending = 2;
 374        } else {
 375                h5_complete_rx_pkt(hu);
 376                h5_reset_rx(h5);
 377        }
 378
 379        return 0;
 380}
 381
 382static int h5_rx_3wire_hdr(struct hci_uart *hu, unsigned char c)
 383{
 384        struct h5 *h5 = hu->priv;
 385        const unsigned char *hdr = h5->rx_skb->data;
 386
 387        BT_DBG("%s rx: seq %u ack %u crc %u rel %u type %u len %u",
 388               hu->hdev->name, H5_HDR_SEQ(hdr), H5_HDR_ACK(hdr),
 389               H5_HDR_CRC(hdr), H5_HDR_RELIABLE(hdr), H5_HDR_PKT_TYPE(hdr),
 390               H5_HDR_LEN(hdr));
 391
 392        if (((hdr[0] + hdr[1] + hdr[2] + hdr[3]) & 0xff) != 0xff) {
 393                BT_ERR("Invalid header checksum");
 394                h5_reset_rx(h5);
 395                return 0;
 396        }
 397
 398        if (H5_HDR_RELIABLE(hdr) && H5_HDR_SEQ(hdr) != h5->tx_ack) {
 399                BT_ERR("Out-of-order packet arrived (%u != %u)",
 400                       H5_HDR_SEQ(hdr), h5->tx_ack);
 401                h5_reset_rx(h5);
 402                return 0;
 403        }
 404
 405        if (h5->state != H5_ACTIVE &&
 406            H5_HDR_PKT_TYPE(hdr) != HCI_3WIRE_LINK_PKT) {
 407                BT_ERR("Non-link packet received in non-active state");
 408                h5_reset_rx(h5);
 409        }
 410
 411        h5->rx_func = h5_rx_payload;
 412        h5->rx_pending = H5_HDR_LEN(hdr);
 413
 414        return 0;
 415}
 416
 417static int h5_rx_pkt_start(struct hci_uart *hu, unsigned char c)
 418{
 419        struct h5 *h5 = hu->priv;
 420
 421        if (c == SLIP_DELIMITER)
 422                return 1;
 423
 424        h5->rx_func = h5_rx_3wire_hdr;
 425        h5->rx_pending = 4;
 426
 427        h5->rx_skb = bt_skb_alloc(H5_MAX_LEN, GFP_ATOMIC);
 428        if (!h5->rx_skb) {
 429                BT_ERR("Can't allocate mem for new packet");
 430                h5_reset_rx(h5);
 431                return -ENOMEM;
 432        }
 433
 434        h5->rx_skb->dev = (void *) hu->hdev;
 435
 436        return 0;
 437}
 438
 439static int h5_rx_delimiter(struct hci_uart *hu, unsigned char c)
 440{
 441        struct h5 *h5 = hu->priv;
 442
 443        if (c == SLIP_DELIMITER)
 444                h5->rx_func = h5_rx_pkt_start;
 445
 446        return 1;
 447}
 448
 449static void h5_unslip_one_byte(struct h5 *h5, unsigned char c)
 450{
 451        const u8 delim = SLIP_DELIMITER, esc = SLIP_ESC;
 452        const u8 *byte = &c;
 453
 454        if (!test_bit(H5_RX_ESC, &h5->flags) && c == SLIP_ESC) {
 455                set_bit(H5_RX_ESC, &h5->flags);
 456                return;
 457        }
 458
 459        if (test_and_clear_bit(H5_RX_ESC, &h5->flags)) {
 460                switch (c) {
 461                case SLIP_ESC_DELIM:
 462                        byte = &delim;
 463                        break;
 464                case SLIP_ESC_ESC:
 465                        byte = &esc;
 466                        break;
 467                default:
 468                        BT_ERR("Invalid esc byte 0x%02hhx", c);
 469                        h5_reset_rx(h5);
 470                        return;
 471                }
 472        }
 473
 474        memcpy(skb_put(h5->rx_skb, 1), byte, 1);
 475        h5->rx_pending--;
 476
 477        BT_DBG("unsliped 0x%02hhx, rx_pending %zu", *byte, h5->rx_pending);
 478}
 479
 480static void h5_reset_rx(struct h5 *h5)
 481{
 482        if (h5->rx_skb) {
 483                kfree_skb(h5->rx_skb);
 484                h5->rx_skb = NULL;
 485        }
 486
 487        h5->rx_func = h5_rx_delimiter;
 488        h5->rx_pending = 0;
 489        clear_bit(H5_RX_ESC, &h5->flags);
 490}
 491
 492static int h5_recv(struct hci_uart *hu, void *data, int count)
 493{
 494        struct h5 *h5 = hu->priv;
 495        unsigned char *ptr = data;
 496
 497        BT_DBG("%s pending %zu count %d", hu->hdev->name, h5->rx_pending,
 498               count);
 499
 500        while (count > 0) {
 501                int processed;
 502
 503                if (h5->rx_pending > 0) {
 504                        if (*ptr == SLIP_DELIMITER) {
 505                                BT_ERR("Too short H5 packet");
 506                                h5_reset_rx(h5);
 507                                continue;
 508                        }
 509
 510                        h5_unslip_one_byte(h5, *ptr);
 511
 512                        ptr++; count--;
 513                        continue;
 514                }
 515
 516                processed = h5->rx_func(hu, *ptr);
 517                if (processed < 0)
 518                        return processed;
 519
 520                ptr += processed;
 521                count -= processed;
 522        }
 523
 524        return 0;
 525}
 526
 527static int h5_enqueue(struct hci_uart *hu, struct sk_buff *skb)
 528{
 529        struct h5 *h5 = hu->priv;
 530
 531        if (skb->len > 0xfff) {
 532                BT_ERR("Packet too long (%u bytes)", skb->len);
 533                kfree_skb(skb);
 534                return 0;
 535        }
 536
 537        if (h5->state != H5_ACTIVE) {
 538                BT_ERR("Ignoring HCI data in non-active state");
 539                kfree_skb(skb);
 540                return 0;
 541        }
 542
 543        switch (bt_cb(skb)->pkt_type) {
 544        case HCI_ACLDATA_PKT:
 545        case HCI_COMMAND_PKT:
 546                skb_queue_tail(&h5->rel, skb);
 547                break;
 548
 549        case HCI_SCODATA_PKT:
 550                skb_queue_tail(&h5->unrel, skb);
 551                break;
 552
 553        default:
 554                BT_ERR("Unknown packet type %u", bt_cb(skb)->pkt_type);
 555                kfree_skb(skb);
 556                break;
 557        }
 558
 559        return 0;
 560}
 561
 562static void h5_slip_delim(struct sk_buff *skb)
 563{
 564        const char delim = SLIP_DELIMITER;
 565
 566        memcpy(skb_put(skb, 1), &delim, 1);
 567}
 568
 569static void h5_slip_one_byte(struct sk_buff *skb, u8 c)
 570{
 571        const char esc_delim[2] = { SLIP_ESC, SLIP_ESC_DELIM };
 572        const char esc_esc[2] = { SLIP_ESC, SLIP_ESC_ESC };
 573
 574        switch (c) {
 575        case SLIP_DELIMITER:
 576                memcpy(skb_put(skb, 2), &esc_delim, 2);
 577                break;
 578        case SLIP_ESC:
 579                memcpy(skb_put(skb, 2), &esc_esc, 2);
 580                break;
 581        default:
 582                memcpy(skb_put(skb, 1), &c, 1);
 583        }
 584}
 585
 586static bool valid_packet_type(u8 type)
 587{
 588        switch (type) {
 589        case HCI_ACLDATA_PKT:
 590        case HCI_COMMAND_PKT:
 591        case HCI_SCODATA_PKT:
 592        case HCI_3WIRE_LINK_PKT:
 593        case HCI_3WIRE_ACK_PKT:
 594                return true;
 595        default:
 596                return false;
 597        }
 598}
 599
 600static struct sk_buff *h5_prepare_pkt(struct hci_uart *hu, u8 pkt_type,
 601                                      const u8 *data, size_t len)
 602{
 603        struct h5 *h5 = hu->priv;
 604        struct sk_buff *nskb;
 605        u8 hdr[4];
 606        int i;
 607
 608        if (!valid_packet_type(pkt_type)) {
 609                BT_ERR("Unknown packet type %u", pkt_type);
 610                return NULL;
 611        }
 612
 613        /*
 614         * Max len of packet: (original len + 4 (H5 hdr) + 2 (crc)) * 2
 615         * (because bytes 0xc0 and 0xdb are escaped, worst case is when
 616         * the packet is all made of 0xc0 and 0xdb) + 2 (0xc0
 617         * delimiters at start and end).
 618         */
 619        nskb = alloc_skb((len + 6) * 2 + 2, GFP_ATOMIC);
 620        if (!nskb)
 621                return NULL;
 622
 623        bt_cb(nskb)->pkt_type = pkt_type;
 624
 625        h5_slip_delim(nskb);
 626
 627        hdr[0] = h5->tx_ack << 3;
 628        clear_bit(H5_TX_ACK_REQ, &h5->flags);
 629
 630        /* Reliable packet? */
 631        if (pkt_type == HCI_ACLDATA_PKT || pkt_type == HCI_COMMAND_PKT) {
 632                hdr[0] |= 1 << 7;
 633                hdr[0] |= h5->tx_seq;
 634                h5->tx_seq = (h5->tx_seq + 1) % 8;
 635        }
 636
 637        hdr[1] = pkt_type | ((len & 0x0f) << 4);
 638        hdr[2] = len >> 4;
 639        hdr[3] = ~((hdr[0] + hdr[1] + hdr[2]) & 0xff);
 640
 641        BT_DBG("%s tx: seq %u ack %u crc %u rel %u type %u len %u",
 642               hu->hdev->name, H5_HDR_SEQ(hdr), H5_HDR_ACK(hdr),
 643               H5_HDR_CRC(hdr), H5_HDR_RELIABLE(hdr), H5_HDR_PKT_TYPE(hdr),
 644               H5_HDR_LEN(hdr));
 645
 646        for (i = 0; i < 4; i++)
 647                h5_slip_one_byte(nskb, hdr[i]);
 648
 649        for (i = 0; i < len; i++)
 650                h5_slip_one_byte(nskb, data[i]);
 651
 652        h5_slip_delim(nskb);
 653
 654        return nskb;
 655}
 656
 657static struct sk_buff *h5_dequeue(struct hci_uart *hu)
 658{
 659        struct h5 *h5 = hu->priv;
 660        unsigned long flags;
 661        struct sk_buff *skb, *nskb;
 662
 663        if (h5->sleep != H5_AWAKE) {
 664                const unsigned char wakeup_req[] = { 0x05, 0xfa };
 665
 666                if (h5->sleep == H5_WAKING_UP)
 667                        return NULL;
 668
 669                h5->sleep = H5_WAKING_UP;
 670                BT_DBG("Sending wakeup request");
 671
 672                mod_timer(&h5->timer, jiffies + HZ / 100);
 673                return h5_prepare_pkt(hu, HCI_3WIRE_LINK_PKT, wakeup_req, 2);
 674        }
 675
 676        if ((skb = skb_dequeue(&h5->unrel)) != NULL) {
 677                nskb = h5_prepare_pkt(hu, bt_cb(skb)->pkt_type,
 678                                      skb->data, skb->len);
 679                if (nskb) {
 680                        kfree_skb(skb);
 681                        return nskb;
 682                }
 683
 684                skb_queue_head(&h5->unrel, skb);
 685                BT_ERR("Could not dequeue pkt because alloc_skb failed");
 686        }
 687
 688        spin_lock_irqsave_nested(&h5->unack.lock, flags, SINGLE_DEPTH_NESTING);
 689
 690        if (h5->unack.qlen >= h5->tx_win)
 691                goto unlock;
 692
 693        if ((skb = skb_dequeue(&h5->rel)) != NULL) {
 694                nskb = h5_prepare_pkt(hu, bt_cb(skb)->pkt_type,
 695                                      skb->data, skb->len);
 696                if (nskb) {
 697                        __skb_queue_tail(&h5->unack, skb);
 698                        mod_timer(&h5->timer, jiffies + H5_ACK_TIMEOUT);
 699                        spin_unlock_irqrestore(&h5->unack.lock, flags);
 700                        return nskb;
 701                }
 702
 703                skb_queue_head(&h5->rel, skb);
 704                BT_ERR("Could not dequeue pkt because alloc_skb failed");
 705        }
 706
 707unlock:
 708        spin_unlock_irqrestore(&h5->unack.lock, flags);
 709
 710        if (test_bit(H5_TX_ACK_REQ, &h5->flags))
 711                return h5_prepare_pkt(hu, HCI_3WIRE_ACK_PKT, NULL, 0);
 712
 713        return NULL;
 714}
 715
 716static int h5_flush(struct hci_uart *hu)
 717{
 718        BT_DBG("hu %p", hu);
 719        return 0;
 720}
 721
 722static struct hci_uart_proto h5p = {
 723        .id             = HCI_UART_3WIRE,
 724        .open           = h5_open,
 725        .close          = h5_close,
 726        .recv           = h5_recv,
 727        .enqueue        = h5_enqueue,
 728        .dequeue        = h5_dequeue,
 729        .flush          = h5_flush,
 730};
 731
 732int __init h5_init(void)
 733{
 734        int err = hci_uart_register_proto(&h5p);
 735
 736        if (!err)
 737                BT_INFO("HCI Three-wire UART (H5) protocol initialized");
 738        else
 739                BT_ERR("HCI Three-wire UART (H5) protocol init failed");
 740
 741        return err;
 742}
 743
 744int __exit h5_deinit(void)
 745{
 746        return hci_uart_unregister_proto(&h5p);
 747}
 748
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