linux/drivers/tty/n_gsm.c
<<
>>
Prefs
   1/*
   2 * n_gsm.c GSM 0710 tty multiplexor
   3 * Copyright (c) 2009/10 Intel Corporation
   4 *
   5 * This program is free software; you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License version 2 as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it will be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write to the Free Software
  16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17 *
  18 *      * THIS IS A DEVELOPMENT SNAPSHOT IT IS NOT A FINAL RELEASE *
  19 *
  20 * TO DO:
  21 *      Mostly done:    ioctls for setting modes/timing
  22 *      Partly done:    hooks so you can pull off frames to non tty devs
  23 *      Restart DLCI 0 when it closes ?
  24 *      Improve the tx engine
  25 *      Resolve tx side locking by adding a queue_head and routing
  26 *              all control traffic via it
  27 *      General tidy/document
  28 *      Review the locking/move to refcounts more (mux now moved to an
  29 *              alloc/free model ready)
  30 *      Use newest tty open/close port helpers and install hooks
  31 *      What to do about power functions ?
  32 *      Termios setting and negotiation
  33 *      Do we need a 'which mux are you' ioctl to correlate mux and tty sets
  34 *
  35 */
  36
  37#include <linux/types.h>
  38#include <linux/major.h>
  39#include <linux/errno.h>
  40#include <linux/signal.h>
  41#include <linux/fcntl.h>
  42#include <linux/sched.h>
  43#include <linux/interrupt.h>
  44#include <linux/tty.h>
  45#include <linux/ctype.h>
  46#include <linux/mm.h>
  47#include <linux/string.h>
  48#include <linux/slab.h>
  49#include <linux/poll.h>
  50#include <linux/bitops.h>
  51#include <linux/file.h>
  52#include <linux/uaccess.h>
  53#include <linux/module.h>
  54#include <linux/timer.h>
  55#include <linux/tty_flip.h>
  56#include <linux/tty_driver.h>
  57#include <linux/serial.h>
  58#include <linux/kfifo.h>
  59#include <linux/skbuff.h>
  60#include <net/arp.h>
  61#include <linux/ip.h>
  62#include <linux/netdevice.h>
  63#include <linux/etherdevice.h>
  64#include <linux/gsmmux.h>
  65
  66static int debug;
  67module_param(debug, int, 0600);
  68
  69/* Defaults: these are from the specification */
  70
  71#define T1      10              /* 100mS */
  72#define T2      34              /* 333mS */
  73#define N2      3               /* Retry 3 times */
  74
  75/* Use long timers for testing at low speed with debug on */
  76#ifdef DEBUG_TIMING
  77#define T1      100
  78#define T2      200
  79#endif
  80
  81/*
  82 * Semi-arbitrary buffer size limits. 0710 is normally run with 32-64 byte
  83 * limits so this is plenty
  84 */
  85#define MAX_MRU 1500
  86#define MAX_MTU 1500
  87#define GSM_NET_TX_TIMEOUT (HZ*10)
  88
  89/**
  90 *      struct gsm_mux_net      -       network interface
  91 *      @struct gsm_dlci* dlci
  92 *      @struct net_device_stats stats;
  93 *
  94 *      Created when net interface is initialized.
  95 **/
  96struct gsm_mux_net {
  97        struct kref ref;
  98        struct gsm_dlci *dlci;
  99        struct net_device_stats stats;
 100};
 101
 102#define STATS(net) (((struct gsm_mux_net *)netdev_priv(net))->stats)
 103
 104/*
 105 *      Each block of data we have queued to go out is in the form of
 106 *      a gsm_msg which holds everything we need in a link layer independent
 107 *      format
 108 */
 109
 110struct gsm_msg {
 111        struct list_head list;
 112        u8 addr;                /* DLCI address + flags */
 113        u8 ctrl;                /* Control byte + flags */
 114        unsigned int len;       /* Length of data block (can be zero) */
 115        unsigned char *data;    /* Points into buffer but not at the start */
 116        unsigned char buffer[0];
 117};
 118
 119/*
 120 *      Each active data link has a gsm_dlci structure associated which ties
 121 *      the link layer to an optional tty (if the tty side is open). To avoid
 122 *      complexity right now these are only ever freed up when the mux is
 123 *      shut down.
 124 *
 125 *      At the moment we don't free DLCI objects until the mux is torn down
 126 *      this avoid object life time issues but might be worth review later.
 127 */
 128
 129struct gsm_dlci {
 130        struct gsm_mux *gsm;
 131        int addr;
 132        int state;
 133#define DLCI_CLOSED             0
 134#define DLCI_OPENING            1       /* Sending SABM not seen UA */
 135#define DLCI_OPEN               2       /* SABM/UA complete */
 136#define DLCI_CLOSING            3       /* Sending DISC not seen UA/DM */
 137        struct mutex mutex;
 138
 139        /* Link layer */
 140        spinlock_t lock;        /* Protects the internal state */
 141        struct timer_list t1;   /* Retransmit timer for SABM and UA */
 142        int retries;
 143        /* Uplink tty if active */
 144        struct tty_port port;   /* The tty bound to this DLCI if there is one */
 145        struct kfifo *fifo;     /* Queue fifo for the DLCI */
 146        struct kfifo _fifo;     /* For new fifo API porting only */
 147        int adaption;           /* Adaption layer in use */
 148        int prev_adaption;
 149        u32 modem_rx;           /* Our incoming virtual modem lines */
 150        u32 modem_tx;           /* Our outgoing modem lines */
 151        int dead;               /* Refuse re-open */
 152        /* Flow control */
 153        int throttled;          /* Private copy of throttle state */
 154        int constipated;        /* Throttle status for outgoing */
 155        /* Packetised I/O */
 156        struct sk_buff *skb;    /* Frame being sent */
 157        struct sk_buff_head skb_list;   /* Queued frames */
 158        /* Data handling callback */
 159        void (*data)(struct gsm_dlci *dlci, u8 *data, int len);
 160        void (*prev_data)(struct gsm_dlci *dlci, u8 *data, int len);
 161        struct net_device *net; /* network interface, if created */
 162};
 163
 164/* DLCI 0, 62/63 are special or reseved see gsmtty_open */
 165
 166#define NUM_DLCI                64
 167
 168/*
 169 *      DLCI 0 is used to pass control blocks out of band of the data
 170 *      flow (and with a higher link priority). One command can be outstanding
 171 *      at a time and we use this structure to manage them. They are created
 172 *      and destroyed by the user context, and updated by the receive paths
 173 *      and timers
 174 */
 175
 176struct gsm_control {
 177        u8 cmd;         /* Command we are issuing */
 178        u8 *data;       /* Data for the command in case we retransmit */
 179        int len;        /* Length of block for retransmission */
 180        int done;       /* Done flag */
 181        int error;      /* Error if any */
 182};
 183
 184/*
 185 *      Each GSM mux we have is represented by this structure. If we are
 186 *      operating as an ldisc then we use this structure as our ldisc
 187 *      state. We need to sort out lifetimes and locking with respect
 188 *      to the gsm mux array. For now we don't free DLCI objects that
 189 *      have been instantiated until the mux itself is terminated.
 190 *
 191 *      To consider further: tty open versus mux shutdown.
 192 */
 193
 194struct gsm_mux {
 195        struct tty_struct *tty;         /* The tty our ldisc is bound to */
 196        spinlock_t lock;
 197        unsigned int num;
 198        struct kref ref;
 199
 200        /* Events on the GSM channel */
 201        wait_queue_head_t event;
 202
 203        /* Bits for GSM mode decoding */
 204
 205        /* Framing Layer */
 206        unsigned char *buf;
 207        int state;
 208#define GSM_SEARCH              0
 209#define GSM_START               1
 210#define GSM_ADDRESS             2
 211#define GSM_CONTROL             3
 212#define GSM_LEN                 4
 213#define GSM_DATA                5
 214#define GSM_FCS                 6
 215#define GSM_OVERRUN             7
 216#define GSM_LEN0                8
 217#define GSM_LEN1                9
 218#define GSM_SSOF                10
 219        unsigned int len;
 220        unsigned int address;
 221        unsigned int count;
 222        int escape;
 223        int encoding;
 224        u8 control;
 225        u8 fcs;
 226        u8 received_fcs;
 227        u8 *txframe;                    /* TX framing buffer */
 228
 229        /* Methods for the receiver side */
 230        void (*receive)(struct gsm_mux *gsm, u8 ch);
 231        void (*error)(struct gsm_mux *gsm, u8 ch, u8 flag);
 232        /* And transmit side */
 233        int (*output)(struct gsm_mux *mux, u8 *data, int len);
 234
 235        /* Link Layer */
 236        unsigned int mru;
 237        unsigned int mtu;
 238        int initiator;                  /* Did we initiate connection */
 239        int dead;                       /* Has the mux been shut down */
 240        struct gsm_dlci *dlci[NUM_DLCI];
 241        int constipated;                /* Asked by remote to shut up */
 242
 243        spinlock_t tx_lock;
 244        unsigned int tx_bytes;          /* TX data outstanding */
 245#define TX_THRESH_HI            8192
 246#define TX_THRESH_LO            2048
 247        struct list_head tx_list;       /* Pending data packets */
 248
 249        /* Control messages */
 250        struct timer_list t2_timer;     /* Retransmit timer for commands */
 251        int cretries;                   /* Command retry counter */
 252        struct gsm_control *pending_cmd;/* Our current pending command */
 253        spinlock_t control_lock;        /* Protects the pending command */
 254
 255        /* Configuration */
 256        int adaption;           /* 1 or 2 supported */
 257        u8 ftype;               /* UI or UIH */
 258        int t1, t2;             /* Timers in 1/100th of a sec */
 259        int n2;                 /* Retry count */
 260
 261        /* Statistics (not currently exposed) */
 262        unsigned long bad_fcs;
 263        unsigned long malformed;
 264        unsigned long io_error;
 265        unsigned long bad_size;
 266        unsigned long unsupported;
 267};
 268
 269
 270/*
 271 *      Mux objects - needed so that we can translate a tty index into the
 272 *      relevant mux and DLCI.
 273 */
 274
 275#define MAX_MUX         4                       /* 256 minors */
 276static struct gsm_mux *gsm_mux[MAX_MUX];        /* GSM muxes */
 277static spinlock_t gsm_mux_lock;
 278
 279static struct tty_driver *gsm_tty_driver;
 280
 281/*
 282 *      This section of the driver logic implements the GSM encodings
 283 *      both the basic and the 'advanced'. Reliable transport is not
 284 *      supported.
 285 */
 286
 287#define CR                      0x02
 288#define EA                      0x01
 289#define PF                      0x10
 290
 291/* I is special: the rest are ..*/
 292#define RR                      0x01
 293#define UI                      0x03
 294#define RNR                     0x05
 295#define REJ                     0x09
 296#define DM                      0x0F
 297#define SABM                    0x2F
 298#define DISC                    0x43
 299#define UA                      0x63
 300#define UIH                     0xEF
 301
 302/* Channel commands */
 303#define CMD_NSC                 0x09
 304#define CMD_TEST                0x11
 305#define CMD_PSC                 0x21
 306#define CMD_RLS                 0x29
 307#define CMD_FCOFF               0x31
 308#define CMD_PN                  0x41
 309#define CMD_RPN                 0x49
 310#define CMD_FCON                0x51
 311#define CMD_CLD                 0x61
 312#define CMD_SNC                 0x69
 313#define CMD_MSC                 0x71
 314
 315/* Virtual modem bits */
 316#define MDM_FC                  0x01
 317#define MDM_RTC                 0x02
 318#define MDM_RTR                 0x04
 319#define MDM_IC                  0x20
 320#define MDM_DV                  0x40
 321
 322#define GSM0_SOF                0xF9
 323#define GSM1_SOF                0x7E
 324#define GSM1_ESCAPE             0x7D
 325#define GSM1_ESCAPE_BITS        0x20
 326#define XON                     0x11
 327#define XOFF                    0x13
 328
 329static const struct tty_port_operations gsm_port_ops;
 330
 331/*
 332 *      CRC table for GSM 0710
 333 */
 334
 335static const u8 gsm_fcs8[256] = {
 336        0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75,
 337        0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B,
 338        0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69,
 339        0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67,
 340        0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D,
 341        0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43,
 342        0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51,
 343        0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F,
 344        0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05,
 345        0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B,
 346        0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19,
 347        0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17,
 348        0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D,
 349        0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33,
 350        0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21,
 351        0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F,
 352        0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95,
 353        0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B,
 354        0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89,
 355        0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87,
 356        0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD,
 357        0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3,
 358        0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1,
 359        0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF,
 360        0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5,
 361        0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB,
 362        0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9,
 363        0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7,
 364        0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD,
 365        0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3,
 366        0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1,
 367        0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF
 368};
 369
 370#define INIT_FCS        0xFF
 371#define GOOD_FCS        0xCF
 372
 373/**
 374 *      gsm_fcs_add     -       update FCS
 375 *      @fcs: Current FCS
 376 *      @c: Next data
 377 *
 378 *      Update the FCS to include c. Uses the algorithm in the specification
 379 *      notes.
 380 */
 381
 382static inline u8 gsm_fcs_add(u8 fcs, u8 c)
 383{
 384        return gsm_fcs8[fcs ^ c];
 385}
 386
 387/**
 388 *      gsm_fcs_add_block       -       update FCS for a block
 389 *      @fcs: Current FCS
 390 *      @c: buffer of data
 391 *      @len: length of buffer
 392 *
 393 *      Update the FCS to include c. Uses the algorithm in the specification
 394 *      notes.
 395 */
 396
 397static inline u8 gsm_fcs_add_block(u8 fcs, u8 *c, int len)
 398{
 399        while (len--)
 400                fcs = gsm_fcs8[fcs ^ *c++];
 401        return fcs;
 402}
 403
 404/**
 405 *      gsm_read_ea             -       read a byte into an EA
 406 *      @val: variable holding value
 407 *      c: byte going into the EA
 408 *
 409 *      Processes one byte of an EA. Updates the passed variable
 410 *      and returns 1 if the EA is now completely read
 411 */
 412
 413static int gsm_read_ea(unsigned int *val, u8 c)
 414{
 415        /* Add the next 7 bits into the value */
 416        *val <<= 7;
 417        *val |= c >> 1;
 418        /* Was this the last byte of the EA 1 = yes*/
 419        return c & EA;
 420}
 421
 422/**
 423 *      gsm_encode_modem        -       encode modem data bits
 424 *      @dlci: DLCI to encode from
 425 *
 426 *      Returns the correct GSM encoded modem status bits (6 bit field) for
 427 *      the current status of the DLCI and attached tty object
 428 */
 429
 430static u8 gsm_encode_modem(const struct gsm_dlci *dlci)
 431{
 432        u8 modembits = 0;
 433        /* FC is true flow control not modem bits */
 434        if (dlci->throttled)
 435                modembits |= MDM_FC;
 436        if (dlci->modem_tx & TIOCM_DTR)
 437                modembits |= MDM_RTC;
 438        if (dlci->modem_tx & TIOCM_RTS)
 439                modembits |= MDM_RTR;
 440        if (dlci->modem_tx & TIOCM_RI)
 441                modembits |= MDM_IC;
 442        if (dlci->modem_tx & TIOCM_CD)
 443                modembits |= MDM_DV;
 444        return modembits;
 445}
 446
 447/**
 448 *      gsm_print_packet        -       display a frame for debug
 449 *      @hdr: header to print before decode
 450 *      @addr: address EA from the frame
 451 *      @cr: C/R bit from the frame
 452 *      @control: control including PF bit
 453 *      @data: following data bytes
 454 *      @dlen: length of data
 455 *
 456 *      Displays a packet in human readable format for debugging purposes. The
 457 *      style is based on amateur radio LAP-B dump display.
 458 */
 459
 460static void gsm_print_packet(const char *hdr, int addr, int cr,
 461                                        u8 control, const u8 *data, int dlen)
 462{
 463        if (!(debug & 1))
 464                return;
 465
 466        pr_info("%s %d) %c: ", hdr, addr, "RC"[cr]);
 467
 468        switch (control & ~PF) {
 469        case SABM:
 470                pr_cont("SABM");
 471                break;
 472        case UA:
 473                pr_cont("UA");
 474                break;
 475        case DISC:
 476                pr_cont("DISC");
 477                break;
 478        case DM:
 479                pr_cont("DM");
 480                break;
 481        case UI:
 482                pr_cont("UI");
 483                break;
 484        case UIH:
 485                pr_cont("UIH");
 486                break;
 487        default:
 488                if (!(control & 0x01)) {
 489                        pr_cont("I N(S)%d N(R)%d",
 490                                (control & 0x0E) >> 1, (control & 0xE0) >> 5);
 491                } else switch (control & 0x0F) {
 492                        case RR:
 493                                pr_cont("RR(%d)", (control & 0xE0) >> 5);
 494                                break;
 495                        case RNR:
 496                                pr_cont("RNR(%d)", (control & 0xE0) >> 5);
 497                                break;
 498                        case REJ:
 499                                pr_cont("REJ(%d)", (control & 0xE0) >> 5);
 500                                break;
 501                        default:
 502                                pr_cont("[%02X]", control);
 503                }
 504        }
 505
 506        if (control & PF)
 507                pr_cont("(P)");
 508        else
 509                pr_cont("(F)");
 510
 511        if (dlen) {
 512                int ct = 0;
 513                while (dlen--) {
 514                        if (ct % 8 == 0) {
 515                                pr_cont("\n");
 516                                pr_debug("    ");
 517                        }
 518                        pr_cont("%02X ", *data++);
 519                        ct++;
 520                }
 521        }
 522        pr_cont("\n");
 523}
 524
 525
 526/*
 527 *      Link level transmission side
 528 */
 529
 530/**
 531 *      gsm_stuff_packet        -       bytestuff a packet
 532 *      @ibuf: input
 533 *      @obuf: output
 534 *      @len: length of input
 535 *
 536 *      Expand a buffer by bytestuffing it. The worst case size change
 537 *      is doubling and the caller is responsible for handing out
 538 *      suitable sized buffers.
 539 */
 540
 541static int gsm_stuff_frame(const u8 *input, u8 *output, int len)
 542{
 543        int olen = 0;
 544        while (len--) {
 545                if (*input == GSM1_SOF || *input == GSM1_ESCAPE
 546                    || *input == XON || *input == XOFF) {
 547                        *output++ = GSM1_ESCAPE;
 548                        *output++ = *input++ ^ GSM1_ESCAPE_BITS;
 549                        olen++;
 550                } else
 551                        *output++ = *input++;
 552                olen++;
 553        }
 554        return olen;
 555}
 556
 557/**
 558 *      gsm_send        -       send a control frame
 559 *      @gsm: our GSM mux
 560 *      @addr: address for control frame
 561 *      @cr: command/response bit
 562 *      @control:  control byte including PF bit
 563 *
 564 *      Format up and transmit a control frame. These do not go via the
 565 *      queueing logic as they should be transmitted ahead of data when
 566 *      they are needed.
 567 *
 568 *      FIXME: Lock versus data TX path
 569 */
 570
 571static void gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
 572{
 573        int len;
 574        u8 cbuf[10];
 575        u8 ibuf[3];
 576
 577        switch (gsm->encoding) {
 578        case 0:
 579                cbuf[0] = GSM0_SOF;
 580                cbuf[1] = (addr << 2) | (cr << 1) | EA;
 581                cbuf[2] = control;
 582                cbuf[3] = EA;   /* Length of data = 0 */
 583                cbuf[4] = 0xFF - gsm_fcs_add_block(INIT_FCS, cbuf + 1, 3);
 584                cbuf[5] = GSM0_SOF;
 585                len = 6;
 586                break;
 587        case 1:
 588        case 2:
 589                /* Control frame + packing (but not frame stuffing) in mode 1 */
 590                ibuf[0] = (addr << 2) | (cr << 1) | EA;
 591                ibuf[1] = control;
 592                ibuf[2] = 0xFF - gsm_fcs_add_block(INIT_FCS, ibuf, 2);
 593                /* Stuffing may double the size worst case */
 594                len = gsm_stuff_frame(ibuf, cbuf + 1, 3);
 595                /* Now add the SOF markers */
 596                cbuf[0] = GSM1_SOF;
 597                cbuf[len + 1] = GSM1_SOF;
 598                /* FIXME: we can omit the lead one in many cases */
 599                len += 2;
 600                break;
 601        default:
 602                WARN_ON(1);
 603                return;
 604        }
 605        gsm->output(gsm, cbuf, len);
 606        gsm_print_packet("-->", addr, cr, control, NULL, 0);
 607}
 608
 609/**
 610 *      gsm_response    -       send a control response
 611 *      @gsm: our GSM mux
 612 *      @addr: address for control frame
 613 *      @control:  control byte including PF bit
 614 *
 615 *      Format up and transmit a link level response frame.
 616 */
 617
 618static inline void gsm_response(struct gsm_mux *gsm, int addr, int control)
 619{
 620        gsm_send(gsm, addr, 0, control);
 621}
 622
 623/**
 624 *      gsm_command     -       send a control command
 625 *      @gsm: our GSM mux
 626 *      @addr: address for control frame
 627 *      @control:  control byte including PF bit
 628 *
 629 *      Format up and transmit a link level command frame.
 630 */
 631
 632static inline void gsm_command(struct gsm_mux *gsm, int addr, int control)
 633{
 634        gsm_send(gsm, addr, 1, control);
 635}
 636
 637/* Data transmission */
 638
 639#define HDR_LEN         6       /* ADDR CTRL [LEN.2] DATA FCS */
 640
 641/**
 642 *      gsm_data_alloc          -       allocate data frame
 643 *      @gsm: GSM mux
 644 *      @addr: DLCI address
 645 *      @len: length excluding header and FCS
 646 *      @ctrl: control byte
 647 *
 648 *      Allocate a new data buffer for sending frames with data. Space is left
 649 *      at the front for header bytes but that is treated as an implementation
 650 *      detail and not for the high level code to use
 651 */
 652
 653static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
 654                                                                u8 ctrl)
 655{
 656        struct gsm_msg *m = kmalloc(sizeof(struct gsm_msg) + len + HDR_LEN,
 657                                                                GFP_ATOMIC);
 658        if (m == NULL)
 659                return NULL;
 660        m->data = m->buffer + HDR_LEN - 1;      /* Allow for FCS */
 661        m->len = len;
 662        m->addr = addr;
 663        m->ctrl = ctrl;
 664        INIT_LIST_HEAD(&m->list);
 665        return m;
 666}
 667
 668/**
 669 *      gsm_data_kick           -       poke the queue
 670 *      @gsm: GSM Mux
 671 *
 672 *      The tty device has called us to indicate that room has appeared in
 673 *      the transmit queue. Ram more data into the pipe if we have any
 674 *      If we have been flow-stopped by a CMD_FCOFF, then we can only
 675 *      send messages on DLCI0 until CMD_FCON
 676 *
 677 *      FIXME: lock against link layer control transmissions
 678 */
 679
 680static void gsm_data_kick(struct gsm_mux *gsm)
 681{
 682        struct gsm_msg *msg, *nmsg;
 683        int len;
 684        int skip_sof = 0;
 685
 686        list_for_each_entry_safe(msg, nmsg, &gsm->tx_list, list) {
 687                if (gsm->constipated && msg->addr)
 688                        continue;
 689                if (gsm->encoding != 0) {
 690                        gsm->txframe[0] = GSM1_SOF;
 691                        len = gsm_stuff_frame(msg->data,
 692                                                gsm->txframe + 1, msg->len);
 693                        gsm->txframe[len + 1] = GSM1_SOF;
 694                        len += 2;
 695                } else {
 696                        gsm->txframe[0] = GSM0_SOF;
 697                        memcpy(gsm->txframe + 1 , msg->data, msg->len);
 698                        gsm->txframe[msg->len + 1] = GSM0_SOF;
 699                        len = msg->len + 2;
 700                }
 701
 702                if (debug & 4)
 703                        print_hex_dump_bytes("gsm_data_kick: ",
 704                                             DUMP_PREFIX_OFFSET,
 705                                             gsm->txframe, len);
 706
 707                if (gsm->output(gsm, gsm->txframe + skip_sof,
 708                                                len - skip_sof) < 0)
 709                        break;
 710                /* FIXME: Can eliminate one SOF in many more cases */
 711                gsm->tx_bytes -= msg->len;
 712                /* For a burst of frames skip the extra SOF within the
 713                   burst */
 714                skip_sof = 1;
 715
 716                list_del(&msg->list);
 717                kfree(msg);
 718        }
 719}
 720
 721/**
 722 *      __gsm_data_queue                -       queue a UI or UIH frame
 723 *      @dlci: DLCI sending the data
 724 *      @msg: message queued
 725 *
 726 *      Add data to the transmit queue and try and get stuff moving
 727 *      out of the mux tty if not already doing so. The Caller must hold
 728 *      the gsm tx lock.
 729 */
 730
 731static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
 732{
 733        struct gsm_mux *gsm = dlci->gsm;
 734        u8 *dp = msg->data;
 735        u8 *fcs = dp + msg->len;
 736
 737        /* Fill in the header */
 738        if (gsm->encoding == 0) {
 739                if (msg->len < 128)
 740                        *--dp = (msg->len << 1) | EA;
 741                else {
 742                        *--dp = (msg->len >> 7);        /* bits 7 - 15 */
 743                        *--dp = (msg->len & 127) << 1;  /* bits 0 - 6 */
 744                }
 745        }
 746
 747        *--dp = msg->ctrl;
 748        if (gsm->initiator)
 749                *--dp = (msg->addr << 2) | 2 | EA;
 750        else
 751                *--dp = (msg->addr << 2) | EA;
 752        *fcs = gsm_fcs_add_block(INIT_FCS, dp , msg->data - dp);
 753        /* Ugly protocol layering violation */
 754        if (msg->ctrl == UI || msg->ctrl == (UI|PF))
 755                *fcs = gsm_fcs_add_block(*fcs, msg->data, msg->len);
 756        *fcs = 0xFF - *fcs;
 757
 758        gsm_print_packet("Q> ", msg->addr, gsm->initiator, msg->ctrl,
 759                                                        msg->data, msg->len);
 760
 761        /* Move the header back and adjust the length, also allow for the FCS
 762           now tacked on the end */
 763        msg->len += (msg->data - dp) + 1;
 764        msg->data = dp;
 765
 766        /* Add to the actual output queue */
 767        list_add_tail(&msg->list, &gsm->tx_list);
 768        gsm->tx_bytes += msg->len;
 769        gsm_data_kick(gsm);
 770}
 771
 772/**
 773 *      gsm_data_queue          -       queue a UI or UIH frame
 774 *      @dlci: DLCI sending the data
 775 *      @msg: message queued
 776 *
 777 *      Add data to the transmit queue and try and get stuff moving
 778 *      out of the mux tty if not already doing so. Take the
 779 *      the gsm tx lock and dlci lock.
 780 */
 781
 782static void gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
 783{
 784        unsigned long flags;
 785        spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
 786        __gsm_data_queue(dlci, msg);
 787        spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
 788}
 789
 790/**
 791 *      gsm_dlci_data_output    -       try and push data out of a DLCI
 792 *      @gsm: mux
 793 *      @dlci: the DLCI to pull data from
 794 *
 795 *      Pull data from a DLCI and send it into the transmit queue if there
 796 *      is data. Keep to the MRU of the mux. This path handles the usual tty
 797 *      interface which is a byte stream with optional modem data.
 798 *
 799 *      Caller must hold the tx_lock of the mux.
 800 */
 801
 802static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci)
 803{
 804        struct gsm_msg *msg;
 805        u8 *dp;
 806        int len, total_size, size;
 807        int h = dlci->adaption - 1;
 808
 809        total_size = 0;
 810        while (1) {
 811                len = kfifo_len(dlci->fifo);
 812                if (len == 0)
 813                        return total_size;
 814
 815                /* MTU/MRU count only the data bits */
 816                if (len > gsm->mtu)
 817                        len = gsm->mtu;
 818
 819                size = len + h;
 820
 821                msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
 822                /* FIXME: need a timer or something to kick this so it can't
 823                   get stuck with no work outstanding and no buffer free */
 824                if (msg == NULL)
 825                        return -ENOMEM;
 826                dp = msg->data;
 827                switch (dlci->adaption) {
 828                case 1: /* Unstructured */
 829                        break;
 830                case 2: /* Unstructed with modem bits.
 831                Always one byte as we never send inline break data */
 832                        *dp++ = gsm_encode_modem(dlci);
 833                        break;
 834                }
 835                WARN_ON(kfifo_out_locked(dlci->fifo, dp , len, &dlci->lock) != len);
 836                __gsm_data_queue(dlci, msg);
 837                total_size += size;
 838        }
 839        /* Bytes of data we used up */
 840        return total_size;
 841}
 842
 843/**
 844 *      gsm_dlci_data_output_framed  -  try and push data out of a DLCI
 845 *      @gsm: mux
 846 *      @dlci: the DLCI to pull data from
 847 *
 848 *      Pull data from a DLCI and send it into the transmit queue if there
 849 *      is data. Keep to the MRU of the mux. This path handles framed data
 850 *      queued as skbuffs to the DLCI.
 851 *
 852 *      Caller must hold the tx_lock of the mux.
 853 */
 854
 855static int gsm_dlci_data_output_framed(struct gsm_mux *gsm,
 856                                                struct gsm_dlci *dlci)
 857{
 858        struct gsm_msg *msg;
 859        u8 *dp;
 860        int len, size;
 861        int last = 0, first = 0;
 862        int overhead = 0;
 863
 864        /* One byte per frame is used for B/F flags */
 865        if (dlci->adaption == 4)
 866                overhead = 1;
 867
 868        /* dlci->skb is locked by tx_lock */
 869        if (dlci->skb == NULL) {
 870                dlci->skb = skb_dequeue_tail(&dlci->skb_list);
 871                if (dlci->skb == NULL)
 872                        return 0;
 873                first = 1;
 874        }
 875        len = dlci->skb->len + overhead;
 876
 877        /* MTU/MRU count only the data bits */
 878        if (len > gsm->mtu) {
 879                if (dlci->adaption == 3) {
 880                        /* Over long frame, bin it */
 881                        dev_kfree_skb_any(dlci->skb);
 882                        dlci->skb = NULL;
 883                        return 0;
 884                }
 885                len = gsm->mtu;
 886        } else
 887                last = 1;
 888
 889        size = len + overhead;
 890        msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
 891
 892        /* FIXME: need a timer or something to kick this so it can't
 893           get stuck with no work outstanding and no buffer free */
 894        if (msg == NULL) {
 895                skb_queue_tail(&dlci->skb_list, dlci->skb);
 896                dlci->skb = NULL;
 897                return -ENOMEM;
 898        }
 899        dp = msg->data;
 900
 901        if (dlci->adaption == 4) { /* Interruptible framed (Packetised Data) */
 902                /* Flag byte to carry the start/end info */
 903                *dp++ = last << 7 | first << 6 | 1;     /* EA */
 904                len--;
 905        }
 906        memcpy(dp, dlci->skb->data, len);
 907        skb_pull(dlci->skb, len);
 908        __gsm_data_queue(dlci, msg);
 909        if (last) {
 910                dev_kfree_skb_any(dlci->skb);
 911                dlci->skb = NULL;
 912        }
 913        return size;
 914}
 915
 916/**
 917 *      gsm_dlci_data_sweep             -       look for data to send
 918 *      @gsm: the GSM mux
 919 *
 920 *      Sweep the GSM mux channels in priority order looking for ones with
 921 *      data to send. We could do with optimising this scan a bit. We aim
 922 *      to fill the queue totally or up to TX_THRESH_HI bytes. Once we hit
 923 *      TX_THRESH_LO we get called again
 924 *
 925 *      FIXME: We should round robin between groups and in theory you can
 926 *      renegotiate DLCI priorities with optional stuff. Needs optimising.
 927 */
 928
 929static void gsm_dlci_data_sweep(struct gsm_mux *gsm)
 930{
 931        int len;
 932        /* Priority ordering: We should do priority with RR of the groups */
 933        int i = 1;
 934
 935        while (i < NUM_DLCI) {
 936                struct gsm_dlci *dlci;
 937
 938                if (gsm->tx_bytes > TX_THRESH_HI)
 939                        break;
 940                dlci = gsm->dlci[i];
 941                if (dlci == NULL || dlci->constipated) {
 942                        i++;
 943                        continue;
 944                }
 945                if (dlci->adaption < 3 && !dlci->net)
 946                        len = gsm_dlci_data_output(gsm, dlci);
 947                else
 948                        len = gsm_dlci_data_output_framed(gsm, dlci);
 949                if (len < 0)
 950                        break;
 951                /* DLCI empty - try the next */
 952                if (len == 0)
 953                        i++;
 954        }
 955}
 956
 957/**
 958 *      gsm_dlci_data_kick      -       transmit if possible
 959 *      @dlci: DLCI to kick
 960 *
 961 *      Transmit data from this DLCI if the queue is empty. We can't rely on
 962 *      a tty wakeup except when we filled the pipe so we need to fire off
 963 *      new data ourselves in other cases.
 964 */
 965
 966static void gsm_dlci_data_kick(struct gsm_dlci *dlci)
 967{
 968        unsigned long flags;
 969        int sweep;
 970
 971        if (dlci->constipated)
 972                return;
 973
 974        spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
 975        /* If we have nothing running then we need to fire up */
 976        sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO);
 977        if (dlci->gsm->tx_bytes == 0) {
 978                if (dlci->net)
 979                        gsm_dlci_data_output_framed(dlci->gsm, dlci);
 980                else
 981                        gsm_dlci_data_output(dlci->gsm, dlci);
 982        }
 983        if (sweep)
 984                gsm_dlci_data_sweep(dlci->gsm);
 985        spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
 986}
 987
 988/*
 989 *      Control message processing
 990 */
 991
 992
 993/**
 994 *      gsm_control_reply       -       send a response frame to a control
 995 *      @gsm: gsm channel
 996 *      @cmd: the command to use
 997 *      @data: data to follow encoded info
 998 *      @dlen: length of data
 999 *
1000 *      Encode up and queue a UI/UIH frame containing our response.
1001 */
1002
1003static void gsm_control_reply(struct gsm_mux *gsm, int cmd, u8 *data,
1004                                        int dlen)
1005{
1006        struct gsm_msg *msg;
1007        msg = gsm_data_alloc(gsm, 0, dlen + 2, gsm->ftype);
1008        if (msg == NULL)
1009                return;
1010        msg->data[0] = (cmd & 0xFE) << 1 | EA;  /* Clear C/R */
1011        msg->data[1] = (dlen << 1) | EA;
1012        memcpy(msg->data + 2, data, dlen);
1013        gsm_data_queue(gsm->dlci[0], msg);
1014}
1015
1016/**
1017 *      gsm_process_modem       -       process received modem status
1018 *      @tty: virtual tty bound to the DLCI
1019 *      @dlci: DLCI to affect
1020 *      @modem: modem bits (full EA)
1021 *
1022 *      Used when a modem control message or line state inline in adaption
1023 *      layer 2 is processed. Sort out the local modem state and throttles
1024 */
1025
1026static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci,
1027                                                        u32 modem, int clen)
1028{
1029        int  mlines = 0;
1030        u8 brk = 0;
1031        int fc;
1032
1033        /* The modem status command can either contain one octet (v.24 signals)
1034           or two octets (v.24 signals + break signals). The length field will
1035           either be 2 or 3 respectively. This is specified in section
1036           5.4.6.3.7 of the  27.010 mux spec. */
1037
1038        if (clen == 2)
1039                modem = modem & 0x7f;
1040        else {
1041                brk = modem & 0x7f;
1042                modem = (modem >> 7) & 0x7f;
1043        }
1044
1045        /* Flow control/ready to communicate */
1046        fc = (modem & MDM_FC) || !(modem & MDM_RTR);
1047        if (fc && !dlci->constipated) {
1048                /* Need to throttle our output on this device */
1049                dlci->constipated = 1;
1050        } else if (!fc && dlci->constipated) {
1051                dlci->constipated = 0;
1052                gsm_dlci_data_kick(dlci);
1053        }
1054
1055        /* Map modem bits */
1056        if (modem & MDM_RTC)
1057                mlines |= TIOCM_DSR | TIOCM_DTR;
1058        if (modem & MDM_RTR)
1059                mlines |= TIOCM_RTS | TIOCM_CTS;
1060        if (modem & MDM_IC)
1061                mlines |= TIOCM_RI;
1062        if (modem & MDM_DV)
1063                mlines |= TIOCM_CD;
1064
1065        /* Carrier drop -> hangup */
1066        if (tty) {
1067                if ((mlines & TIOCM_CD) == 0 && (dlci->modem_rx & TIOCM_CD))
1068                        if (!(tty->termios.c_cflag & CLOCAL))
1069                                tty_hangup(tty);
1070        }
1071        if (brk & 0x01)
1072                tty_insert_flip_char(&dlci->port, 0, TTY_BREAK);
1073        dlci->modem_rx = mlines;
1074}
1075
1076/**
1077 *      gsm_control_modem       -       modem status received
1078 *      @gsm: GSM channel
1079 *      @data: data following command
1080 *      @clen: command length
1081 *
1082 *      We have received a modem status control message. This is used by
1083 *      the GSM mux protocol to pass virtual modem line status and optionally
1084 *      to indicate break signals. Unpack it, convert to Linux representation
1085 *      and if need be stuff a break message down the tty.
1086 */
1087
1088static void gsm_control_modem(struct gsm_mux *gsm, u8 *data, int clen)
1089{
1090        unsigned int addr = 0;
1091        unsigned int modem = 0;
1092        struct gsm_dlci *dlci;
1093        int len = clen;
1094        u8 *dp = data;
1095        struct tty_struct *tty;
1096
1097        while (gsm_read_ea(&addr, *dp++) == 0) {
1098                len--;
1099                if (len == 0)
1100                        return;
1101        }
1102        /* Must be at least one byte following the EA */
1103        len--;
1104        if (len <= 0)
1105                return;
1106
1107        addr >>= 1;
1108        /* Closed port, or invalid ? */
1109        if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1110                return;
1111        dlci = gsm->dlci[addr];
1112
1113        while (gsm_read_ea(&modem, *dp++) == 0) {
1114                len--;
1115                if (len == 0)
1116                        return;
1117        }
1118        tty = tty_port_tty_get(&dlci->port);
1119        gsm_process_modem(tty, dlci, modem, clen);
1120        if (tty) {
1121                tty_wakeup(tty);
1122                tty_kref_put(tty);
1123        }
1124        gsm_control_reply(gsm, CMD_MSC, data, clen);
1125}
1126
1127/**
1128 *      gsm_control_rls         -       remote line status
1129 *      @gsm: GSM channel
1130 *      @data: data bytes
1131 *      @clen: data length
1132 *
1133 *      The modem sends us a two byte message on the control channel whenever
1134 *      it wishes to send us an error state from the virtual link. Stuff
1135 *      this into the uplink tty if present
1136 */
1137
1138static void gsm_control_rls(struct gsm_mux *gsm, u8 *data, int clen)
1139{
1140        struct tty_port *port;
1141        unsigned int addr = 0;
1142        u8 bits;
1143        int len = clen;
1144        u8 *dp = data;
1145
1146        while (gsm_read_ea(&addr, *dp++) == 0) {
1147                len--;
1148                if (len == 0)
1149                        return;
1150        }
1151        /* Must be at least one byte following ea */
1152        len--;
1153        if (len <= 0)
1154                return;
1155        addr >>= 1;
1156        /* Closed port, or invalid ? */
1157        if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1158                return;
1159        /* No error ? */
1160        bits = *dp;
1161        if ((bits & 1) == 0)
1162                return;
1163
1164        port = &gsm->dlci[addr]->port;
1165
1166        if (bits & 2)
1167                tty_insert_flip_char(port, 0, TTY_OVERRUN);
1168        if (bits & 4)
1169                tty_insert_flip_char(port, 0, TTY_PARITY);
1170        if (bits & 8)
1171                tty_insert_flip_char(port, 0, TTY_FRAME);
1172
1173        tty_flip_buffer_push(port);
1174
1175        gsm_control_reply(gsm, CMD_RLS, data, clen);
1176}
1177
1178static void gsm_dlci_begin_close(struct gsm_dlci *dlci);
1179
1180/**
1181 *      gsm_control_message     -       DLCI 0 control processing
1182 *      @gsm: our GSM mux
1183 *      @command:  the command EA
1184 *      @data: data beyond the command/length EAs
1185 *      @clen: length
1186 *
1187 *      Input processor for control messages from the other end of the link.
1188 *      Processes the incoming request and queues a response frame or an
1189 *      NSC response if not supported
1190 */
1191
1192static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
1193                                                        u8 *data, int clen)
1194{
1195        u8 buf[1];
1196        unsigned long flags;
1197
1198        switch (command) {
1199        case CMD_CLD: {
1200                struct gsm_dlci *dlci = gsm->dlci[0];
1201                /* Modem wishes to close down */
1202                if (dlci) {
1203                        dlci->dead = 1;
1204                        gsm->dead = 1;
1205                        gsm_dlci_begin_close(dlci);
1206                }
1207                }
1208                break;
1209        case CMD_TEST:
1210                /* Modem wishes to test, reply with the data */
1211                gsm_control_reply(gsm, CMD_TEST, data, clen);
1212                break;
1213        case CMD_FCON:
1214                /* Modem can accept data again */
1215                gsm->constipated = 0;
1216                gsm_control_reply(gsm, CMD_FCON, NULL, 0);
1217                /* Kick the link in case it is idling */
1218                spin_lock_irqsave(&gsm->tx_lock, flags);
1219                gsm_data_kick(gsm);
1220                spin_unlock_irqrestore(&gsm->tx_lock, flags);
1221                break;
1222        case CMD_FCOFF:
1223                /* Modem wants us to STFU */
1224                gsm->constipated = 1;
1225                gsm_control_reply(gsm, CMD_FCOFF, NULL, 0);
1226                break;
1227        case CMD_MSC:
1228                /* Out of band modem line change indicator for a DLCI */
1229                gsm_control_modem(gsm, data, clen);
1230                break;
1231        case CMD_RLS:
1232                /* Out of band error reception for a DLCI */
1233                gsm_control_rls(gsm, data, clen);
1234                break;
1235        case CMD_PSC:
1236                /* Modem wishes to enter power saving state */
1237                gsm_control_reply(gsm, CMD_PSC, NULL, 0);
1238                break;
1239                /* Optional unsupported commands */
1240        case CMD_PN:    /* Parameter negotiation */
1241        case CMD_RPN:   /* Remote port negotiation */
1242        case CMD_SNC:   /* Service negotiation command */
1243        default:
1244                /* Reply to bad commands with an NSC */
1245                buf[0] = command;
1246                gsm_control_reply(gsm, CMD_NSC, buf, 1);
1247                break;
1248        }
1249}
1250
1251/**
1252 *      gsm_control_response    -       process a response to our control
1253 *      @gsm: our GSM mux
1254 *      @command: the command (response) EA
1255 *      @data: data beyond the command/length EA
1256 *      @clen: length
1257 *
1258 *      Process a response to an outstanding command. We only allow a single
1259 *      control message in flight so this is fairly easy. All the clean up
1260 *      is done by the caller, we just update the fields, flag it as done
1261 *      and return
1262 */
1263
1264static void gsm_control_response(struct gsm_mux *gsm, unsigned int command,
1265                                                        u8 *data, int clen)
1266{
1267        struct gsm_control *ctrl;
1268        unsigned long flags;
1269
1270        spin_lock_irqsave(&gsm->control_lock, flags);
1271
1272        ctrl = gsm->pending_cmd;
1273        /* Does the reply match our command */
1274        command |= 1;
1275        if (ctrl != NULL && (command == ctrl->cmd || command == CMD_NSC)) {
1276                /* Our command was replied to, kill the retry timer */
1277                del_timer(&gsm->t2_timer);
1278                gsm->pending_cmd = NULL;
1279                /* Rejected by the other end */
1280                if (command == CMD_NSC)
1281                        ctrl->error = -EOPNOTSUPP;
1282                ctrl->done = 1;
1283                wake_up(&gsm->event);
1284        }
1285        spin_unlock_irqrestore(&gsm->control_lock, flags);
1286}
1287
1288/**
1289 *      gsm_control_transmit    -       send control packet
1290 *      @gsm: gsm mux
1291 *      @ctrl: frame to send
1292 *
1293 *      Send out a pending control command (called under control lock)
1294 */
1295
1296static void gsm_control_transmit(struct gsm_mux *gsm, struct gsm_control *ctrl)
1297{
1298        struct gsm_msg *msg = gsm_data_alloc(gsm, 0, ctrl->len + 1, gsm->ftype);
1299        if (msg == NULL)
1300                return;
1301        msg->data[0] = (ctrl->cmd << 1) | 2 | EA;       /* command */
1302        memcpy(msg->data + 1, ctrl->data, ctrl->len);
1303        gsm_data_queue(gsm->dlci[0], msg);
1304}
1305
1306/**
1307 *      gsm_control_retransmit  -       retransmit a control frame
1308 *      @data: pointer to our gsm object
1309 *
1310 *      Called off the T2 timer expiry in order to retransmit control frames
1311 *      that have been lost in the system somewhere. The control_lock protects
1312 *      us from colliding with another sender or a receive completion event.
1313 *      In that situation the timer may still occur in a small window but
1314 *      gsm->pending_cmd will be NULL and we just let the timer expire.
1315 */
1316
1317static void gsm_control_retransmit(unsigned long data)
1318{
1319        struct gsm_mux *gsm = (struct gsm_mux *)data;
1320        struct gsm_control *ctrl;
1321        unsigned long flags;
1322        spin_lock_irqsave(&gsm->control_lock, flags);
1323        ctrl = gsm->pending_cmd;
1324        if (ctrl) {
1325                gsm->cretries--;
1326                if (gsm->cretries == 0) {
1327                        gsm->pending_cmd = NULL;
1328                        ctrl->error = -ETIMEDOUT;
1329                        ctrl->done = 1;
1330                        spin_unlock_irqrestore(&gsm->control_lock, flags);
1331                        wake_up(&gsm->event);
1332                        return;
1333                }
1334                gsm_control_transmit(gsm, ctrl);
1335                mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
1336        }
1337        spin_unlock_irqrestore(&gsm->control_lock, flags);
1338}
1339
1340/**
1341 *      gsm_control_send        -       send a control frame on DLCI 0
1342 *      @gsm: the GSM channel
1343 *      @command: command  to send including CR bit
1344 *      @data: bytes of data (must be kmalloced)
1345 *      @len: length of the block to send
1346 *
1347 *      Queue and dispatch a control command. Only one command can be
1348 *      active at a time. In theory more can be outstanding but the matching
1349 *      gets really complicated so for now stick to one outstanding.
1350 */
1351
1352static struct gsm_control *gsm_control_send(struct gsm_mux *gsm,
1353                unsigned int command, u8 *data, int clen)
1354{
1355        struct gsm_control *ctrl = kzalloc(sizeof(struct gsm_control),
1356                                                GFP_KERNEL);
1357        unsigned long flags;
1358        if (ctrl == NULL)
1359                return NULL;
1360retry:
1361        wait_event(gsm->event, gsm->pending_cmd == NULL);
1362        spin_lock_irqsave(&gsm->control_lock, flags);
1363        if (gsm->pending_cmd != NULL) {
1364                spin_unlock_irqrestore(&gsm->control_lock, flags);
1365                goto retry;
1366        }
1367        ctrl->cmd = command;
1368        ctrl->data = data;
1369        ctrl->len = clen;
1370        gsm->pending_cmd = ctrl;
1371        gsm->cretries = gsm->n2;
1372        mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
1373        gsm_control_transmit(gsm, ctrl);
1374        spin_unlock_irqrestore(&gsm->control_lock, flags);
1375        return ctrl;
1376}
1377
1378/**
1379 *      gsm_control_wait        -       wait for a control to finish
1380 *      @gsm: GSM mux
1381 *      @control: control we are waiting on
1382 *
1383 *      Waits for the control to complete or time out. Frees any used
1384 *      resources and returns 0 for success, or an error if the remote
1385 *      rejected or ignored the request.
1386 */
1387
1388static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control)
1389{
1390        int err;
1391        wait_event(gsm->event, control->done == 1);
1392        err = control->error;
1393        kfree(control);
1394        return err;
1395}
1396
1397
1398/*
1399 *      DLCI level handling: Needs krefs
1400 */
1401
1402/*
1403 *      State transitions and timers
1404 */
1405
1406/**
1407 *      gsm_dlci_close          -       a DLCI has closed
1408 *      @dlci: DLCI that closed
1409 *
1410 *      Perform processing when moving a DLCI into closed state. If there
1411 *      is an attached tty this is hung up
1412 */
1413
1414static void gsm_dlci_close(struct gsm_dlci *dlci)
1415{
1416        del_timer(&dlci->t1);
1417        if (debug & 8)
1418                pr_debug("DLCI %d goes closed.\n", dlci->addr);
1419        dlci->state = DLCI_CLOSED;
1420        if (dlci->addr != 0) {
1421                tty_port_tty_hangup(&dlci->port, false);
1422                kfifo_reset(dlci->fifo);
1423        } else
1424                dlci->gsm->dead = 1;
1425        wake_up(&dlci->gsm->event);
1426        /* A DLCI 0 close is a MUX termination so we need to kick that
1427           back to userspace somehow */
1428}
1429
1430/**
1431 *      gsm_dlci_open           -       a DLCI has opened
1432 *      @dlci: DLCI that opened
1433 *
1434 *      Perform processing when moving a DLCI into open state.
1435 */
1436
1437static void gsm_dlci_open(struct gsm_dlci *dlci)
1438{
1439        /* Note that SABM UA .. SABM UA first UA lost can mean that we go
1440           open -> open */
1441        del_timer(&dlci->t1);
1442        /* This will let a tty open continue */
1443        dlci->state = DLCI_OPEN;
1444        if (debug & 8)
1445                pr_debug("DLCI %d goes open.\n", dlci->addr);
1446        wake_up(&dlci->gsm->event);
1447}
1448
1449/**
1450 *      gsm_dlci_t1             -       T1 timer expiry
1451 *      @dlci: DLCI that opened
1452 *
1453 *      The T1 timer handles retransmits of control frames (essentially of
1454 *      SABM and DISC). We resend the command until the retry count runs out
1455 *      in which case an opening port goes back to closed and a closing port
1456 *      is simply put into closed state (any further frames from the other
1457 *      end will get a DM response)
1458 */
1459
1460static void gsm_dlci_t1(unsigned long data)
1461{
1462        struct gsm_dlci *dlci = (struct gsm_dlci *)data;
1463        struct gsm_mux *gsm = dlci->gsm;
1464
1465        switch (dlci->state) {
1466        case DLCI_OPENING:
1467                dlci->retries--;
1468                if (dlci->retries) {
1469                        gsm_command(dlci->gsm, dlci->addr, SABM|PF);
1470                        mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1471                } else
1472                        gsm_dlci_close(dlci);
1473                break;
1474        case DLCI_CLOSING:
1475                dlci->retries--;
1476                if (dlci->retries) {
1477                        gsm_command(dlci->gsm, dlci->addr, DISC|PF);
1478                        mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1479                } else
1480                        gsm_dlci_close(dlci);
1481                break;
1482        }
1483}
1484
1485/**
1486 *      gsm_dlci_begin_open     -       start channel open procedure
1487 *      @dlci: DLCI to open
1488 *
1489 *      Commence opening a DLCI from the Linux side. We issue SABM messages
1490 *      to the modem which should then reply with a UA, at which point we
1491 *      will move into open state. Opening is done asynchronously with retry
1492 *      running off timers and the responses.
1493 */
1494
1495static void gsm_dlci_begin_open(struct gsm_dlci *dlci)
1496{
1497        struct gsm_mux *gsm = dlci->gsm;
1498        if (dlci->state == DLCI_OPEN || dlci->state == DLCI_OPENING)
1499                return;
1500        dlci->retries = gsm->n2;
1501        dlci->state = DLCI_OPENING;
1502        gsm_command(dlci->gsm, dlci->addr, SABM|PF);
1503        mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1504}
1505
1506/**
1507 *      gsm_dlci_begin_close    -       start channel open procedure
1508 *      @dlci: DLCI to open
1509 *
1510 *      Commence closing a DLCI from the Linux side. We issue DISC messages
1511 *      to the modem which should then reply with a UA, at which point we
1512 *      will move into closed state. Closing is done asynchronously with retry
1513 *      off timers. We may also receive a DM reply from the other end which
1514 *      indicates the channel was already closed.
1515 */
1516
1517static void gsm_dlci_begin_close(struct gsm_dlci *dlci)
1518{
1519        struct gsm_mux *gsm = dlci->gsm;
1520        if (dlci->state == DLCI_CLOSED || dlci->state == DLCI_CLOSING)
1521                return;
1522        dlci->retries = gsm->n2;
1523        dlci->state = DLCI_CLOSING;
1524        gsm_command(dlci->gsm, dlci->addr, DISC|PF);
1525        mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1526}
1527
1528/**
1529 *      gsm_dlci_data           -       data arrived
1530 *      @dlci: channel
1531 *      @data: block of bytes received
1532 *      @len: length of received block
1533 *
1534 *      A UI or UIH frame has arrived which contains data for a channel
1535 *      other than the control channel. If the relevant virtual tty is
1536 *      open we shovel the bits down it, if not we drop them.
1537 */
1538
1539static void gsm_dlci_data(struct gsm_dlci *dlci, u8 *data, int clen)
1540{
1541        /* krefs .. */
1542        struct tty_port *port = &dlci->port;
1543        struct tty_struct *tty;
1544        unsigned int modem = 0;
1545        int len = clen;
1546
1547        if (debug & 16)
1548                pr_debug("%d bytes for tty\n", len);
1549        switch (dlci->adaption)  {
1550        /* Unsupported types */
1551        /* Packetised interruptible data */
1552        case 4:
1553                break;
1554        /* Packetised uininterruptible voice/data */
1555        case 3:
1556                break;
1557        /* Asynchronous serial with line state in each frame */
1558        case 2:
1559                while (gsm_read_ea(&modem, *data++) == 0) {
1560                        len--;
1561                        if (len == 0)
1562                                return;
1563                }
1564                tty = tty_port_tty_get(port);
1565                if (tty) {
1566                        gsm_process_modem(tty, dlci, modem, clen);
1567                        tty_kref_put(tty);
1568                }
1569        /* Line state will go via DLCI 0 controls only */
1570        case 1:
1571        default:
1572                tty_insert_flip_string(port, data, len);
1573                tty_flip_buffer_push(port);
1574        }
1575}
1576
1577/**
1578 *      gsm_dlci_control        -       data arrived on control channel
1579 *      @dlci: channel
1580 *      @data: block of bytes received
1581 *      @len: length of received block
1582 *
1583 *      A UI or UIH frame has arrived which contains data for DLCI 0 the
1584 *      control channel. This should contain a command EA followed by
1585 *      control data bytes. The command EA contains a command/response bit
1586 *      and we divide up the work accordingly.
1587 */
1588
1589static void gsm_dlci_command(struct gsm_dlci *dlci, u8 *data, int len)
1590{
1591        /* See what command is involved */
1592        unsigned int command = 0;
1593        while (len-- > 0) {
1594                if (gsm_read_ea(&command, *data++) == 1) {
1595                        int clen = *data++;
1596                        len--;
1597                        /* FIXME: this is properly an EA */
1598                        clen >>= 1;
1599                        /* Malformed command ? */
1600                        if (clen > len)
1601                                return;
1602                        if (command & 1)
1603                                gsm_control_message(dlci->gsm, command,
1604                                                                data, clen);
1605                        else
1606                                gsm_control_response(dlci->gsm, command,
1607                                                                data, clen);
1608                        return;
1609                }
1610        }
1611}
1612
1613/*
1614 *      Allocate/Free DLCI channels
1615 */
1616
1617/**
1618 *      gsm_dlci_alloc          -       allocate a DLCI
1619 *      @gsm: GSM mux
1620 *      @addr: address of the DLCI
1621 *
1622 *      Allocate and install a new DLCI object into the GSM mux.
1623 *
1624 *      FIXME: review locking races
1625 */
1626
1627static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr)
1628{
1629        struct gsm_dlci *dlci = kzalloc(sizeof(struct gsm_dlci), GFP_ATOMIC);
1630        if (dlci == NULL)
1631                return NULL;
1632        spin_lock_init(&dlci->lock);
1633        mutex_init(&dlci->mutex);
1634        dlci->fifo = &dlci->_fifo;
1635        if (kfifo_alloc(&dlci->_fifo, 4096, GFP_KERNEL) < 0) {
1636                kfree(dlci);
1637                return NULL;
1638        }
1639
1640        skb_queue_head_init(&dlci->skb_list);
1641        init_timer(&dlci->t1);
1642        dlci->t1.function = gsm_dlci_t1;
1643        dlci->t1.data = (unsigned long)dlci;
1644        tty_port_init(&dlci->port);
1645        dlci->port.ops = &gsm_port_ops;
1646        dlci->gsm = gsm;
1647        dlci->addr = addr;
1648        dlci->adaption = gsm->adaption;
1649        dlci->state = DLCI_CLOSED;
1650        if (addr)
1651                dlci->data = gsm_dlci_data;
1652        else
1653                dlci->data = gsm_dlci_command;
1654        gsm->dlci[addr] = dlci;
1655        return dlci;
1656}
1657
1658/**
1659 *      gsm_dlci_free           -       free DLCI
1660 *      @dlci: DLCI to free
1661 *
1662 *      Free up a DLCI.
1663 *
1664 *      Can sleep.
1665 */
1666static void gsm_dlci_free(struct tty_port *port)
1667{
1668        struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
1669
1670        del_timer_sync(&dlci->t1);
1671        dlci->gsm->dlci[dlci->addr] = NULL;
1672        kfifo_free(dlci->fifo);
1673        while ((dlci->skb = skb_dequeue(&dlci->skb_list)))
1674                dev_kfree_skb(dlci->skb);
1675        kfree(dlci);
1676}
1677
1678static inline void dlci_get(struct gsm_dlci *dlci)
1679{
1680        tty_port_get(&dlci->port);
1681}
1682
1683static inline void dlci_put(struct gsm_dlci *dlci)
1684{
1685        tty_port_put(&dlci->port);
1686}
1687
1688static void gsm_destroy_network(struct gsm_dlci *dlci);
1689
1690/**
1691 *      gsm_dlci_release                -       release DLCI
1692 *      @dlci: DLCI to destroy
1693 *
1694 *      Release a DLCI. Actual free is deferred until either
1695 *      mux is closed or tty is closed - whichever is last.
1696 *
1697 *      Can sleep.
1698 */
1699static void gsm_dlci_release(struct gsm_dlci *dlci)
1700{
1701        struct tty_struct *tty = tty_port_tty_get(&dlci->port);
1702        if (tty) {
1703                mutex_lock(&dlci->mutex);
1704                gsm_destroy_network(dlci);
1705                mutex_unlock(&dlci->mutex);
1706
1707                /* tty_vhangup needs the tty_lock, so unlock and
1708                   relock after doing the hangup. */
1709                tty_unlock(tty);
1710                tty_vhangup(tty);
1711                tty_lock(tty);
1712                tty_port_tty_set(&dlci->port, NULL);
1713                tty_kref_put(tty);
1714        }
1715        dlci->state = DLCI_CLOSED;
1716        dlci_put(dlci);
1717}
1718
1719/*
1720 *      LAPBish link layer logic
1721 */
1722
1723/**
1724 *      gsm_queue               -       a GSM frame is ready to process
1725 *      @gsm: pointer to our gsm mux
1726 *
1727 *      At this point in time a frame has arrived and been demangled from
1728 *      the line encoding. All the differences between the encodings have
1729 *      been handled below us and the frame is unpacked into the structures.
1730 *      The fcs holds the header FCS but any data FCS must be added here.
1731 */
1732
1733static void gsm_queue(struct gsm_mux *gsm)
1734{
1735        struct gsm_dlci *dlci;
1736        u8 cr;
1737        int address;
1738        /* We have to sneak a look at the packet body to do the FCS.
1739           A somewhat layering violation in the spec */
1740
1741        if ((gsm->control & ~PF) == UI)
1742                gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf, gsm->len);
1743        if (gsm->encoding == 0) {
1744                /* WARNING: gsm->received_fcs is used for
1745                gsm->encoding = 0 only.
1746                In this case it contain the last piece of data
1747                required to generate final CRC */
1748                gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs);
1749        }
1750        if (gsm->fcs != GOOD_FCS) {
1751                gsm->bad_fcs++;
1752                if (debug & 4)
1753                        pr_debug("BAD FCS %02x\n", gsm->fcs);
1754                return;
1755        }
1756        address = gsm->address >> 1;
1757        if (address >= NUM_DLCI)
1758                goto invalid;
1759
1760        cr = gsm->address & 1;          /* C/R bit */
1761
1762        gsm_print_packet("<--", address, cr, gsm->control, gsm->buf, gsm->len);
1763
1764        cr ^= 1 - gsm->initiator;       /* Flip so 1 always means command */
1765        dlci = gsm->dlci[address];
1766
1767        switch (gsm->control) {
1768        case SABM|PF:
1769                if (cr == 0)
1770                        goto invalid;
1771                if (dlci == NULL)
1772                        dlci = gsm_dlci_alloc(gsm, address);
1773                if (dlci == NULL)
1774                        return;
1775                if (dlci->dead)
1776                        gsm_response(gsm, address, DM);
1777                else {
1778                        gsm_response(gsm, address, UA);
1779                        gsm_dlci_open(dlci);
1780                }
1781                break;
1782        case DISC|PF:
1783                if (cr == 0)
1784                        goto invalid;
1785                if (dlci == NULL || dlci->state == DLCI_CLOSED) {
1786                        gsm_response(gsm, address, DM);
1787                        return;
1788                }
1789                /* Real close complete */
1790                gsm_response(gsm, address, UA);
1791                gsm_dlci_close(dlci);
1792                break;
1793        case UA:
1794        case UA|PF:
1795                if (cr == 0 || dlci == NULL)
1796                        break;
1797                switch (dlci->state) {
1798                case DLCI_CLOSING:
1799                        gsm_dlci_close(dlci);
1800                        break;
1801                case DLCI_OPENING:
1802                        gsm_dlci_open(dlci);
1803                        break;
1804                }
1805                break;
1806        case DM:        /* DM can be valid unsolicited */
1807        case DM|PF:
1808                if (cr)
1809                        goto invalid;
1810                if (dlci == NULL)
1811                        return;
1812                gsm_dlci_close(dlci);
1813                break;
1814        case UI:
1815        case UI|PF:
1816        case UIH:
1817        case UIH|PF:
1818#if 0
1819                if (cr)
1820                        goto invalid;
1821#endif
1822                if (dlci == NULL || dlci->state != DLCI_OPEN) {
1823                        gsm_command(gsm, address, DM|PF);
1824                        return;
1825                }
1826                dlci->data(dlci, gsm->buf, gsm->len);
1827                break;
1828        default:
1829                goto invalid;
1830        }
1831        return;
1832invalid:
1833        gsm->malformed++;
1834        return;
1835}
1836
1837
1838/**
1839 *      gsm0_receive    -       perform processing for non-transparency
1840 *      @gsm: gsm data for this ldisc instance
1841 *      @c: character
1842 *
1843 *      Receive bytes in gsm mode 0
1844 */
1845
1846static void gsm0_receive(struct gsm_mux *gsm, unsigned char c)
1847{
1848        unsigned int len;
1849
1850        switch (gsm->state) {
1851        case GSM_SEARCH:        /* SOF marker */
1852                if (c == GSM0_SOF) {
1853                        gsm->state = GSM_ADDRESS;
1854                        gsm->address = 0;
1855                        gsm->len = 0;
1856                        gsm->fcs = INIT_FCS;
1857                }
1858                break;
1859        case GSM_ADDRESS:       /* Address EA */
1860                gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1861                if (gsm_read_ea(&gsm->address, c))
1862                        gsm->state = GSM_CONTROL;
1863                break;
1864        case GSM_CONTROL:       /* Control Byte */
1865                gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1866                gsm->control = c;
1867                gsm->state = GSM_LEN0;
1868                break;
1869        case GSM_LEN0:          /* Length EA */
1870                gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1871                if (gsm_read_ea(&gsm->len, c)) {
1872                        if (gsm->len > gsm->mru) {
1873                                gsm->bad_size++;
1874                                gsm->state = GSM_SEARCH;
1875                                break;
1876                        }
1877                        gsm->count = 0;
1878                        if (!gsm->len)
1879                                gsm->state = GSM_FCS;
1880                        else
1881                                gsm->state = GSM_DATA;
1882                        break;
1883                }
1884                gsm->state = GSM_LEN1;
1885                break;
1886        case GSM_LEN1:
1887                gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1888                len = c;
1889                gsm->len |= len << 7;
1890                if (gsm->len > gsm->mru) {
1891                        gsm->bad_size++;
1892                        gsm->state = GSM_SEARCH;
1893                        break;
1894                }
1895                gsm->count = 0;
1896                if (!gsm->len)
1897                        gsm->state = GSM_FCS;
1898                else
1899                        gsm->state = GSM_DATA;
1900                break;
1901        case GSM_DATA:          /* Data */
1902                gsm->buf[gsm->count++] = c;
1903                if (gsm->count == gsm->len)
1904                        gsm->state = GSM_FCS;
1905                break;
1906        case GSM_FCS:           /* FCS follows the packet */
1907                gsm->received_fcs = c;
1908                gsm_queue(gsm);
1909                gsm->state = GSM_SSOF;
1910                break;
1911        case GSM_SSOF:
1912                if (c == GSM0_SOF) {
1913                        gsm->state = GSM_SEARCH;
1914                        break;
1915                }
1916                break;
1917        }
1918}
1919
1920/**
1921 *      gsm1_receive    -       perform processing for non-transparency
1922 *      @gsm: gsm data for this ldisc instance
1923 *      @c: character
1924 *
1925 *      Receive bytes in mode 1 (Advanced option)
1926 */
1927
1928static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
1929{
1930        if (c == GSM1_SOF) {
1931                /* EOF is only valid in frame if we have got to the data state
1932                   and received at least one byte (the FCS) */
1933                if (gsm->state == GSM_DATA && gsm->count) {
1934                        /* Extract the FCS */
1935                        gsm->count--;
1936                        gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]);
1937                        gsm->len = gsm->count;
1938                        gsm_queue(gsm);
1939                        gsm->state  = GSM_START;
1940                        return;
1941                }
1942                /* Any partial frame was a runt so go back to start */
1943                if (gsm->state != GSM_START) {
1944                        gsm->malformed++;
1945                        gsm->state = GSM_START;
1946                }
1947                /* A SOF in GSM_START means we are still reading idling or
1948                   framing bytes */
1949                return;
1950        }
1951
1952        if (c == GSM1_ESCAPE) {
1953                gsm->escape = 1;
1954                return;
1955        }
1956
1957        /* Only an unescaped SOF gets us out of GSM search */
1958        if (gsm->state == GSM_SEARCH)
1959                return;
1960
1961        if (gsm->escape) {
1962                c ^= GSM1_ESCAPE_BITS;
1963                gsm->escape = 0;
1964        }
1965        switch (gsm->state) {
1966        case GSM_START:         /* First byte after SOF */
1967                gsm->address = 0;
1968                gsm->state = GSM_ADDRESS;
1969                gsm->fcs = INIT_FCS;
1970                /* Drop through */
1971        case GSM_ADDRESS:       /* Address continuation */
1972                gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1973                if (gsm_read_ea(&gsm->address, c))
1974                        gsm->state = GSM_CONTROL;
1975                break;
1976        case GSM_CONTROL:       /* Control Byte */
1977                gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1978                gsm->control = c;
1979                gsm->count = 0;
1980                gsm->state = GSM_DATA;
1981                break;
1982        case GSM_DATA:          /* Data */
1983                if (gsm->count > gsm->mru) {    /* Allow one for the FCS */
1984                        gsm->state = GSM_OVERRUN;
1985                        gsm->bad_size++;
1986                } else
1987                        gsm->buf[gsm->count++] = c;
1988                break;
1989        case GSM_OVERRUN:       /* Over-long - eg a dropped SOF */
1990                break;
1991        }
1992}
1993
1994/**
1995 *      gsm_error               -       handle tty error
1996 *      @gsm: ldisc data
1997 *      @data: byte received (may be invalid)
1998 *      @flag: error received
1999 *
2000 *      Handle an error in the receipt of data for a frame. Currently we just
2001 *      go back to hunting for a SOF.
2002 *
2003 *      FIXME: better diagnostics ?
2004 */
2005
2006static void gsm_error(struct gsm_mux *gsm,
2007                                unsigned char data, unsigned char flag)
2008{
2009        gsm->state = GSM_SEARCH;
2010        gsm->io_error++;
2011}
2012
2013/**
2014 *      gsm_cleanup_mux         -       generic GSM protocol cleanup
2015 *      @gsm: our mux
2016 *
2017 *      Clean up the bits of the mux which are the same for all framing
2018 *      protocols. Remove the mux from the mux table, stop all the timers
2019 *      and then shut down each device hanging up the channels as we go.
2020 */
2021
2022void gsm_cleanup_mux(struct gsm_mux *gsm)
2023{
2024        int i;
2025        struct gsm_dlci *dlci = gsm->dlci[0];
2026        struct gsm_msg *txq, *ntxq;
2027        struct gsm_control *gc;
2028
2029        gsm->dead = 1;
2030
2031        spin_lock(&gsm_mux_lock);
2032        for (i = 0; i < MAX_MUX; i++) {
2033                if (gsm_mux[i] == gsm) {
2034                        gsm_mux[i] = NULL;
2035                        break;
2036                }
2037        }
2038        spin_unlock(&gsm_mux_lock);
2039        WARN_ON(i == MAX_MUX);
2040
2041        /* In theory disconnecting DLCI 0 is sufficient but for some
2042           modems this is apparently not the case. */
2043        if (dlci) {
2044                gc = gsm_control_send(gsm, CMD_CLD, NULL, 0);
2045                if (gc)
2046                        gsm_control_wait(gsm, gc);
2047        }
2048        del_timer_sync(&gsm->t2_timer);
2049        /* Now we are sure T2 has stopped */
2050        if (dlci) {
2051                dlci->dead = 1;
2052                gsm_dlci_begin_close(dlci);
2053                wait_event_interruptible(gsm->event,
2054                                        dlci->state == DLCI_CLOSED);
2055        }
2056        /* Free up any link layer users */
2057        for (i = 0; i < NUM_DLCI; i++)
2058                if (gsm->dlci[i])
2059                        gsm_dlci_release(gsm->dlci[i]);
2060        /* Now wipe the queues */
2061        list_for_each_entry_safe(txq, ntxq, &gsm->tx_list, list)
2062                kfree(txq);
2063        INIT_LIST_HEAD(&gsm->tx_list);
2064}
2065EXPORT_SYMBOL_GPL(gsm_cleanup_mux);
2066
2067/**
2068 *      gsm_activate_mux        -       generic GSM setup
2069 *      @gsm: our mux
2070 *
2071 *      Set up the bits of the mux which are the same for all framing
2072 *      protocols. Add the mux to the mux table so it can be opened and
2073 *      finally kick off connecting to DLCI 0 on the modem.
2074 */
2075
2076int gsm_activate_mux(struct gsm_mux *gsm)
2077{
2078        struct gsm_dlci *dlci;
2079        int i = 0;
2080
2081        init_timer(&gsm->t2_timer);
2082        gsm->t2_timer.function = gsm_control_retransmit;
2083        gsm->t2_timer.data = (unsigned long)gsm;
2084        init_waitqueue_head(&gsm->event);
2085        spin_lock_init(&gsm->control_lock);
2086        spin_lock_init(&gsm->tx_lock);
2087
2088        if (gsm->encoding == 0)
2089                gsm->receive = gsm0_receive;
2090        else
2091                gsm->receive = gsm1_receive;
2092        gsm->error = gsm_error;
2093
2094        spin_lock(&gsm_mux_lock);
2095        for (i = 0; i < MAX_MUX; i++) {
2096                if (gsm_mux[i] == NULL) {
2097                        gsm->num = i;
2098                        gsm_mux[i] = gsm;
2099                        break;
2100                }
2101        }
2102        spin_unlock(&gsm_mux_lock);
2103        if (i == MAX_MUX)
2104                return -EBUSY;
2105
2106        dlci = gsm_dlci_alloc(gsm, 0);
2107        if (dlci == NULL)
2108                return -ENOMEM;
2109        gsm->dead = 0;          /* Tty opens are now permissible */
2110        return 0;
2111}
2112EXPORT_SYMBOL_GPL(gsm_activate_mux);
2113
2114/**
2115 *      gsm_free_mux            -       free up a mux
2116 *      @mux: mux to free
2117 *
2118 *      Dispose of allocated resources for a dead mux
2119 */
2120void gsm_free_mux(struct gsm_mux *gsm)
2121{
2122        kfree(gsm->txframe);
2123        kfree(gsm->buf);
2124        kfree(gsm);
2125}
2126EXPORT_SYMBOL_GPL(gsm_free_mux);
2127
2128/**
2129 *      gsm_free_muxr           -       free up a mux
2130 *      @mux: mux to free
2131 *
2132 *      Dispose of allocated resources for a dead mux
2133 */
2134static void gsm_free_muxr(struct kref *ref)
2135{
2136        struct gsm_mux *gsm = container_of(ref, struct gsm_mux, ref);
2137        gsm_free_mux(gsm);
2138}
2139
2140static inline void mux_get(struct gsm_mux *gsm)
2141{
2142        kref_get(&gsm->ref);
2143}
2144
2145static inline void mux_put(struct gsm_mux *gsm)
2146{
2147        kref_put(&gsm->ref, gsm_free_muxr);
2148}
2149
2150/**
2151 *      gsm_alloc_mux           -       allocate a mux
2152 *
2153 *      Creates a new mux ready for activation.
2154 */
2155
2156struct gsm_mux *gsm_alloc_mux(void)
2157{
2158        struct gsm_mux *gsm = kzalloc(sizeof(struct gsm_mux), GFP_KERNEL);
2159        if (gsm == NULL)
2160                return NULL;
2161        gsm->buf = kmalloc(MAX_MRU + 1, GFP_KERNEL);
2162        if (gsm->buf == NULL) {
2163                kfree(gsm);
2164                return NULL;
2165        }
2166        gsm->txframe = kmalloc(2 * MAX_MRU + 2, GFP_KERNEL);
2167        if (gsm->txframe == NULL) {
2168                kfree(gsm->buf);
2169                kfree(gsm);
2170                return NULL;
2171        }
2172        spin_lock_init(&gsm->lock);
2173        kref_init(&gsm->ref);
2174        INIT_LIST_HEAD(&gsm->tx_list);
2175
2176        gsm->t1 = T1;
2177        gsm->t2 = T2;
2178        gsm->n2 = N2;
2179        gsm->ftype = UIH;
2180        gsm->adaption = 1;
2181        gsm->encoding = 1;
2182        gsm->mru = 64;  /* Default to encoding 1 so these should be 64 */
2183        gsm->mtu = 64;
2184        gsm->dead = 1;  /* Avoid early tty opens */
2185
2186        return gsm;
2187}
2188EXPORT_SYMBOL_GPL(gsm_alloc_mux);
2189
2190/**
2191 *      gsmld_output            -       write to link
2192 *      @gsm: our mux
2193 *      @data: bytes to output
2194 *      @len: size
2195 *
2196 *      Write a block of data from the GSM mux to the data channel. This
2197 *      will eventually be serialized from above but at the moment isn't.
2198 */
2199
2200static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len)
2201{
2202        if (tty_write_room(gsm->tty) < len) {
2203                set_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
2204                return -ENOSPC;
2205        }
2206        if (debug & 4)
2207                print_hex_dump_bytes("gsmld_output: ", DUMP_PREFIX_OFFSET,
2208                                     data, len);
2209        gsm->tty->ops->write(gsm->tty, data, len);
2210        return len;
2211}
2212
2213/**
2214 *      gsmld_attach_gsm        -       mode set up
2215 *      @tty: our tty structure
2216 *      @gsm: our mux
2217 *
2218 *      Set up the MUX for basic mode and commence connecting to the
2219 *      modem. Currently called from the line discipline set up but
2220 *      will need moving to an ioctl path.
2221 */
2222
2223static int gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2224{
2225        int ret, i;
2226        int base = gsm->num << 6; /* Base for this MUX */
2227
2228        gsm->tty = tty_kref_get(tty);
2229        gsm->output = gsmld_output;
2230        ret =  gsm_activate_mux(gsm);
2231        if (ret != 0)
2232                tty_kref_put(gsm->tty);
2233        else {
2234                /* Don't register device 0 - this is the control channel and not
2235                   a usable tty interface */
2236                for (i = 1; i < NUM_DLCI; i++)
2237                        tty_register_device(gsm_tty_driver, base + i, NULL);
2238        }
2239        return ret;
2240}
2241
2242
2243/**
2244 *      gsmld_detach_gsm        -       stop doing 0710 mux
2245 *      @tty: tty attached to the mux
2246 *      @gsm: mux
2247 *
2248 *      Shutdown and then clean up the resources used by the line discipline
2249 */
2250
2251static void gsmld_detach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2252{
2253        int i;
2254        int base = gsm->num << 6; /* Base for this MUX */
2255
2256        WARN_ON(tty != gsm->tty);
2257        for (i = 1; i < NUM_DLCI; i++)
2258                tty_unregister_device(gsm_tty_driver, base + i);
2259        gsm_cleanup_mux(gsm);
2260        tty_kref_put(gsm->tty);
2261        gsm->tty = NULL;
2262}
2263
2264static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp,
2265                              char *fp, int count)
2266{
2267        struct gsm_mux *gsm = tty->disc_data;
2268        const unsigned char *dp;
2269        char *f;
2270        int i;
2271        char buf[64];
2272        char flags;
2273
2274        if (debug & 4)
2275                print_hex_dump_bytes("gsmld_receive: ", DUMP_PREFIX_OFFSET,
2276                                     cp, count);
2277
2278        for (i = count, dp = cp, f = fp; i; i--, dp++) {
2279                flags = *f++;
2280                switch (flags) {
2281                case TTY_NORMAL:
2282                        gsm->receive(gsm, *dp);
2283                        break;
2284                case TTY_OVERRUN:
2285                case TTY_BREAK:
2286                case TTY_PARITY:
2287                case TTY_FRAME:
2288                        gsm->error(gsm, *dp, flags);
2289                        break;
2290                default:
2291                        WARN_ONCE(1, "%s: unknown flag %d\n",
2292                               tty_name(tty, buf), flags);
2293                        break;
2294                }
2295        }
2296        /* FASYNC if needed ? */
2297        /* If clogged call tty_throttle(tty); */
2298}
2299
2300/**
2301 *      gsmld_chars_in_buffer   -       report available bytes
2302 *      @tty: tty device
2303 *
2304 *      Report the number of characters buffered to be delivered to user
2305 *      at this instant in time.
2306 *
2307 *      Locking: gsm lock
2308 */
2309
2310static ssize_t gsmld_chars_in_buffer(struct tty_struct *tty)
2311{
2312        return 0;
2313}
2314
2315/**
2316 *      gsmld_flush_buffer      -       clean input queue
2317 *      @tty:   terminal device
2318 *
2319 *      Flush the input buffer. Called when the line discipline is
2320 *      being closed, when the tty layer wants the buffer flushed (eg
2321 *      at hangup).
2322 */
2323
2324static void gsmld_flush_buffer(struct tty_struct *tty)
2325{
2326}
2327
2328/**
2329 *      gsmld_close             -       close the ldisc for this tty
2330 *      @tty: device
2331 *
2332 *      Called from the terminal layer when this line discipline is
2333 *      being shut down, either because of a close or becsuse of a
2334 *      discipline change. The function will not be called while other
2335 *      ldisc methods are in progress.
2336 */
2337
2338static void gsmld_close(struct tty_struct *tty)
2339{
2340        struct gsm_mux *gsm = tty->disc_data;
2341
2342        gsmld_detach_gsm(tty, gsm);
2343
2344        gsmld_flush_buffer(tty);
2345        /* Do other clean up here */
2346        mux_put(gsm);
2347}
2348
2349/**
2350 *      gsmld_open              -       open an ldisc
2351 *      @tty: terminal to open
2352 *
2353 *      Called when this line discipline is being attached to the
2354 *      terminal device. Can sleep. Called serialized so that no
2355 *      other events will occur in parallel. No further open will occur
2356 *      until a close.
2357 */
2358
2359static int gsmld_open(struct tty_struct *tty)
2360{
2361        struct gsm_mux *gsm;
2362
2363        if (tty->ops->write == NULL)
2364                return -EINVAL;
2365
2366        /* Attach our ldisc data */
2367        gsm = gsm_alloc_mux();
2368        if (gsm == NULL)
2369                return -ENOMEM;
2370
2371        tty->disc_data = gsm;
2372        tty->receive_room = 65536;
2373
2374        /* Attach the initial passive connection */
2375        gsm->encoding = 1;
2376        return gsmld_attach_gsm(tty, gsm);
2377}
2378
2379/**
2380 *      gsmld_write_wakeup      -       asynchronous I/O notifier
2381 *      @tty: tty device
2382 *
2383 *      Required for the ptys, serial driver etc. since processes
2384 *      that attach themselves to the master and rely on ASYNC
2385 *      IO must be woken up
2386 */
2387
2388static void gsmld_write_wakeup(struct tty_struct *tty)
2389{
2390        struct gsm_mux *gsm = tty->disc_data;
2391        unsigned long flags;
2392
2393        /* Queue poll */
2394        clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2395        spin_lock_irqsave(&gsm->tx_lock, flags);
2396        gsm_data_kick(gsm);
2397        if (gsm->tx_bytes < TX_THRESH_LO) {
2398                gsm_dlci_data_sweep(gsm);
2399        }
2400        spin_unlock_irqrestore(&gsm->tx_lock, flags);
2401}
2402
2403/**
2404 *      gsmld_read              -       read function for tty
2405 *      @tty: tty device
2406 *      @file: file object
2407 *      @buf: userspace buffer pointer
2408 *      @nr: size of I/O
2409 *
2410 *      Perform reads for the line discipline. We are guaranteed that the
2411 *      line discipline will not be closed under us but we may get multiple
2412 *      parallel readers and must handle this ourselves. We may also get
2413 *      a hangup. Always called in user context, may sleep.
2414 *
2415 *      This code must be sure never to sleep through a hangup.
2416 */
2417
2418static ssize_t gsmld_read(struct tty_struct *tty, struct file *file,
2419                         unsigned char __user *buf, size_t nr)
2420{
2421        return -EOPNOTSUPP;
2422}
2423
2424/**
2425 *      gsmld_write             -       write function for tty
2426 *      @tty: tty device
2427 *      @file: file object
2428 *      @buf: userspace buffer pointer
2429 *      @nr: size of I/O
2430 *
2431 *      Called when the owner of the device wants to send a frame
2432 *      itself (or some other control data). The data is transferred
2433 *      as-is and must be properly framed and checksummed as appropriate
2434 *      by userspace. Frames are either sent whole or not at all as this
2435 *      avoids pain user side.
2436 */
2437
2438static ssize_t gsmld_write(struct tty_struct *tty, struct file *file,
2439                           const unsigned char *buf, size_t nr)
2440{
2441        int space = tty_write_room(tty);
2442        if (space >= nr)
2443                return tty->ops->write(tty, buf, nr);
2444        set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2445        return -ENOBUFS;
2446}
2447
2448/**
2449 *      gsmld_poll              -       poll method for N_GSM0710
2450 *      @tty: terminal device
2451 *      @file: file accessing it
2452 *      @wait: poll table
2453 *
2454 *      Called when the line discipline is asked to poll() for data or
2455 *      for special events. This code is not serialized with respect to
2456 *      other events save open/close.
2457 *
2458 *      This code must be sure never to sleep through a hangup.
2459 *      Called without the kernel lock held - fine
2460 */
2461
2462static unsigned int gsmld_poll(struct tty_struct *tty, struct file *file,
2463                                                        poll_table *wait)
2464{
2465        unsigned int mask = 0;
2466        struct gsm_mux *gsm = tty->disc_data;
2467
2468        poll_wait(file, &tty->read_wait, wait);
2469        poll_wait(file, &tty->write_wait, wait);
2470        if (tty_hung_up_p(file))
2471                mask |= POLLHUP;
2472        if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0)
2473                mask |= POLLOUT | POLLWRNORM;
2474        if (gsm->dead)
2475                mask |= POLLHUP;
2476        return mask;
2477}
2478
2479static int gsmld_config(struct tty_struct *tty, struct gsm_mux *gsm,
2480                                                        struct gsm_config *c)
2481{
2482        int need_close = 0;
2483        int need_restart = 0;
2484
2485        /* Stuff we don't support yet - UI or I frame transport, windowing */
2486        if ((c->adaption != 1 && c->adaption != 2) || c->k)
2487                return -EOPNOTSUPP;
2488        /* Check the MRU/MTU range looks sane */
2489        if (c->mru > MAX_MRU || c->mtu > MAX_MTU || c->mru < 8 || c->mtu < 8)
2490                return -EINVAL;
2491        if (c->n2 < 3)
2492                return -EINVAL;
2493        if (c->encapsulation > 1)       /* Basic, advanced, no I */
2494                return -EINVAL;
2495        if (c->initiator > 1)
2496                return -EINVAL;
2497        if (c->i == 0 || c->i > 2)      /* UIH and UI only */
2498                return -EINVAL;
2499        /*
2500         *      See what is needed for reconfiguration
2501         */
2502
2503        /* Timing fields */
2504        if (c->t1 != 0 && c->t1 != gsm->t1)
2505                need_restart = 1;
2506        if (c->t2 != 0 && c->t2 != gsm->t2)
2507                need_restart = 1;
2508        if (c->encapsulation != gsm->encoding)
2509                need_restart = 1;
2510        if (c->adaption != gsm->adaption)
2511                need_restart = 1;
2512        /* Requires care */
2513        if (c->initiator != gsm->initiator)
2514                need_close = 1;
2515        if (c->mru != gsm->mru)
2516                need_restart = 1;
2517        if (c->mtu != gsm->mtu)
2518                need_restart = 1;
2519
2520        /*
2521         *      Close down what is needed, restart and initiate the new
2522         *      configuration
2523         */
2524
2525        if (need_close || need_restart) {
2526                gsm_dlci_begin_close(gsm->dlci[0]);
2527                /* This will timeout if the link is down due to N2 expiring */
2528                wait_event_interruptible(gsm->event,
2529                                gsm->dlci[0]->state == DLCI_CLOSED);
2530                if (signal_pending(current))
2531                        return -EINTR;
2532        }
2533        if (need_restart)
2534                gsm_cleanup_mux(gsm);
2535
2536        gsm->initiator = c->initiator;
2537        gsm->mru = c->mru;
2538        gsm->mtu = c->mtu;
2539        gsm->encoding = c->encapsulation;
2540        gsm->adaption = c->adaption;
2541        gsm->n2 = c->n2;
2542
2543        if (c->i == 1)
2544                gsm->ftype = UIH;
2545        else if (c->i == 2)
2546                gsm->ftype = UI;
2547
2548        if (c->t1)
2549                gsm->t1 = c->t1;
2550        if (c->t2)
2551                gsm->t2 = c->t2;
2552
2553        /* FIXME: We need to separate activation/deactivation from adding
2554           and removing from the mux array */
2555        if (need_restart)
2556                gsm_activate_mux(gsm);
2557        if (gsm->initiator && need_close)
2558                gsm_dlci_begin_open(gsm->dlci[0]);
2559        return 0;
2560}
2561
2562static int gsmld_ioctl(struct tty_struct *tty, struct file *file,
2563                       unsigned int cmd, unsigned long arg)
2564{
2565        struct gsm_config c;
2566        struct gsm_mux *gsm = tty->disc_data;
2567
2568        switch (cmd) {
2569        case GSMIOC_GETCONF:
2570                memset(&c, 0, sizeof(c));
2571                c.adaption = gsm->adaption;
2572                c.encapsulation = gsm->encoding;
2573                c.initiator = gsm->initiator;
2574                c.t1 = gsm->t1;
2575                c.t2 = gsm->t2;
2576                c.t3 = 0;       /* Not supported */
2577                c.n2 = gsm->n2;
2578                if (gsm->ftype == UIH)
2579                        c.i = 1;
2580                else
2581                        c.i = 2;
2582                pr_debug("Ftype %d i %d\n", gsm->ftype, c.i);
2583                c.mru = gsm->mru;
2584                c.mtu = gsm->mtu;
2585                c.k = 0;
2586                if (copy_to_user((void *)arg, &c, sizeof(c)))
2587                        return -EFAULT;
2588                return 0;
2589        case GSMIOC_SETCONF:
2590                if (copy_from_user(&c, (void *)arg, sizeof(c)))
2591                        return -EFAULT;
2592                return gsmld_config(tty, gsm, &c);
2593        default:
2594                return n_tty_ioctl_helper(tty, file, cmd, arg);
2595        }
2596}
2597
2598/*
2599 *      Network interface
2600 *
2601 */
2602
2603static int gsm_mux_net_open(struct net_device *net)
2604{
2605        pr_debug("%s called\n", __func__);
2606        netif_start_queue(net);
2607        return 0;
2608}
2609
2610static int gsm_mux_net_close(struct net_device *net)
2611{
2612        netif_stop_queue(net);
2613        return 0;
2614}
2615
2616static struct net_device_stats *gsm_mux_net_get_stats(struct net_device *net)
2617{
2618        return &((struct gsm_mux_net *)netdev_priv(net))->stats;
2619}
2620static void dlci_net_free(struct gsm_dlci *dlci)
2621{
2622        if (!dlci->net) {
2623                WARN_ON(1);
2624                return;
2625        }
2626        dlci->adaption = dlci->prev_adaption;
2627        dlci->data = dlci->prev_data;
2628        free_netdev(dlci->net);
2629        dlci->net = NULL;
2630}
2631static void net_free(struct kref *ref)
2632{
2633        struct gsm_mux_net *mux_net;
2634        struct gsm_dlci *dlci;
2635
2636        mux_net = container_of(ref, struct gsm_mux_net, ref);
2637        dlci = mux_net->dlci;
2638
2639        if (dlci->net) {
2640                unregister_netdev(dlci->net);
2641                dlci_net_free(dlci);
2642        }
2643}
2644
2645static inline void muxnet_get(struct gsm_mux_net *mux_net)
2646{
2647        kref_get(&mux_net->ref);
2648}
2649
2650static inline void muxnet_put(struct gsm_mux_net *mux_net)
2651{
2652        kref_put(&mux_net->ref, net_free);
2653}
2654
2655static int gsm_mux_net_start_xmit(struct sk_buff *skb,
2656                                      struct net_device *net)
2657{
2658        struct gsm_mux_net *mux_net = (struct gsm_mux_net *)netdev_priv(net);
2659        struct gsm_dlci *dlci = mux_net->dlci;
2660        muxnet_get(mux_net);
2661
2662        skb_queue_head(&dlci->skb_list, skb);
2663        STATS(net).tx_packets++;
2664        STATS(net).tx_bytes += skb->len;
2665        gsm_dlci_data_kick(dlci);
2666        /* And tell the kernel when the last transmit started. */
2667        net->trans_start = jiffies;
2668        muxnet_put(mux_net);
2669        return NETDEV_TX_OK;
2670}
2671
2672/* called when a packet did not ack after watchdogtimeout */
2673static void gsm_mux_net_tx_timeout(struct net_device *net)
2674{
2675        /* Tell syslog we are hosed. */
2676        dev_dbg(&net->dev, "Tx timed out.\n");
2677
2678        /* Update statistics */
2679        STATS(net).tx_errors++;
2680}
2681
2682static void gsm_mux_rx_netchar(struct gsm_dlci *dlci,
2683                                   unsigned char *in_buf, int size)
2684{
2685        struct net_device *net = dlci->net;
2686        struct sk_buff *skb;
2687        struct gsm_mux_net *mux_net = (struct gsm_mux_net *)netdev_priv(net);
2688        muxnet_get(mux_net);
2689
2690        /* Allocate an sk_buff */
2691        skb = dev_alloc_skb(size + NET_IP_ALIGN);
2692        if (!skb) {
2693                /* We got no receive buffer. */
2694                STATS(net).rx_dropped++;
2695                muxnet_put(mux_net);
2696                return;
2697        }
2698        skb_reserve(skb, NET_IP_ALIGN);
2699        memcpy(skb_put(skb, size), in_buf, size);
2700
2701        skb->dev = net;
2702        skb->protocol = __constant_htons(ETH_P_IP);
2703
2704        /* Ship it off to the kernel */
2705        netif_rx(skb);
2706
2707        /* update out statistics */
2708        STATS(net).rx_packets++;
2709        STATS(net).rx_bytes += size;
2710        muxnet_put(mux_net);
2711        return;
2712}
2713
2714int gsm_change_mtu(struct net_device *net, int new_mtu)
2715{
2716        struct gsm_mux_net *mux_net = (struct gsm_mux_net *)netdev_priv(net);
2717        if ((new_mtu < 8) || (new_mtu > mux_net->dlci->gsm->mtu))
2718                return -EINVAL;
2719        net->mtu = new_mtu;
2720        return 0;
2721}
2722
2723static void gsm_mux_net_init(struct net_device *net)
2724{
2725        static const struct net_device_ops gsm_netdev_ops = {
2726                .ndo_open               = gsm_mux_net_open,
2727                .ndo_stop               = gsm_mux_net_close,
2728                .ndo_start_xmit         = gsm_mux_net_start_xmit,
2729                .ndo_tx_timeout         = gsm_mux_net_tx_timeout,
2730                .ndo_get_stats          = gsm_mux_net_get_stats,
2731                .ndo_change_mtu         = gsm_change_mtu,
2732        };
2733
2734        net->netdev_ops = &gsm_netdev_ops;
2735
2736        /* fill in the other fields */
2737        net->watchdog_timeo = GSM_NET_TX_TIMEOUT;
2738        net->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
2739        net->type = ARPHRD_NONE;
2740        net->tx_queue_len = 10;
2741}
2742
2743
2744/* caller holds the dlci mutex */
2745static void gsm_destroy_network(struct gsm_dlci *dlci)
2746{
2747        struct gsm_mux_net *mux_net;
2748
2749        pr_debug("destroy network interface");
2750        if (!dlci->net)
2751                return;
2752        mux_net = (struct gsm_mux_net *)netdev_priv(dlci->net);
2753        muxnet_put(mux_net);
2754}
2755
2756
2757/* caller holds the dlci mutex */
2758static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc)
2759{
2760        char *netname;
2761        int retval = 0;
2762        struct net_device *net;
2763        struct gsm_mux_net *mux_net;
2764
2765        if (!capable(CAP_NET_ADMIN))
2766                return -EPERM;
2767
2768        /* Already in a non tty mode */
2769        if (dlci->adaption > 2)
2770                return -EBUSY;
2771
2772        if (nc->protocol != htons(ETH_P_IP))
2773                return -EPROTONOSUPPORT;
2774
2775        if (nc->adaption != 3 && nc->adaption != 4)
2776                return -EPROTONOSUPPORT;
2777
2778        pr_debug("create network interface");
2779
2780        netname = "gsm%d";
2781        if (nc->if_name[0] != '\0')
2782                netname = nc->if_name;
2783        net = alloc_netdev(sizeof(struct gsm_mux_net),
2784                        netname,
2785                        gsm_mux_net_init);
2786        if (!net) {
2787                pr_err("alloc_netdev failed");
2788                return -ENOMEM;
2789        }
2790        net->mtu = dlci->gsm->mtu;
2791        mux_net = (struct gsm_mux_net *)netdev_priv(net);
2792        mux_net->dlci = dlci;
2793        kref_init(&mux_net->ref);
2794        strncpy(nc->if_name, net->name, IFNAMSIZ); /* return net name */
2795
2796        /* reconfigure dlci for network */
2797        dlci->prev_adaption = dlci->adaption;
2798        dlci->prev_data = dlci->data;
2799        dlci->adaption = nc->adaption;
2800        dlci->data = gsm_mux_rx_netchar;
2801        dlci->net = net;
2802
2803        pr_debug("register netdev");
2804        retval = register_netdev(net);
2805        if (retval) {
2806                pr_err("network register fail %d\n", retval);
2807                dlci_net_free(dlci);
2808                return retval;
2809        }
2810        return net->ifindex;    /* return network index */
2811}
2812
2813/* Line discipline for real tty */
2814struct tty_ldisc_ops tty_ldisc_packet = {
2815        .owner           = THIS_MODULE,
2816        .magic           = TTY_LDISC_MAGIC,
2817        .name            = "n_gsm",
2818        .open            = gsmld_open,
2819        .close           = gsmld_close,
2820        .flush_buffer    = gsmld_flush_buffer,
2821        .chars_in_buffer = gsmld_chars_in_buffer,
2822        .read            = gsmld_read,
2823        .write           = gsmld_write,
2824        .ioctl           = gsmld_ioctl,
2825        .poll            = gsmld_poll,
2826        .receive_buf     = gsmld_receive_buf,
2827        .write_wakeup    = gsmld_write_wakeup
2828};
2829
2830/*
2831 *      Virtual tty side
2832 */
2833
2834#define TX_SIZE         512
2835
2836static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk)
2837{
2838        u8 modembits[5];
2839        struct gsm_control *ctrl;
2840        int len = 2;
2841
2842        if (brk)
2843                len++;
2844
2845        modembits[0] = len << 1 | EA;           /* Data bytes */
2846        modembits[1] = dlci->addr << 2 | 3;     /* DLCI, EA, 1 */
2847        modembits[2] = gsm_encode_modem(dlci) << 1 | EA;
2848        if (brk)
2849                modembits[3] = brk << 4 | 2 | EA;       /* Valid, EA */
2850        ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len + 1);
2851        if (ctrl == NULL)
2852                return -ENOMEM;
2853        return gsm_control_wait(dlci->gsm, ctrl);
2854}
2855
2856static int gsm_carrier_raised(struct tty_port *port)
2857{
2858        struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2859        /* Not yet open so no carrier info */
2860        if (dlci->state != DLCI_OPEN)
2861                return 0;
2862        if (debug & 2)
2863                return 1;
2864        return dlci->modem_rx & TIOCM_CD;
2865}
2866
2867static void gsm_dtr_rts(struct tty_port *port, int onoff)
2868{
2869        struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2870        unsigned int modem_tx = dlci->modem_tx;
2871        if (onoff)
2872                modem_tx |= TIOCM_DTR | TIOCM_RTS;
2873        else
2874                modem_tx &= ~(TIOCM_DTR | TIOCM_RTS);
2875        if (modem_tx != dlci->modem_tx) {
2876                dlci->modem_tx = modem_tx;
2877                gsmtty_modem_update(dlci, 0);
2878        }
2879}
2880
2881static const struct tty_port_operations gsm_port_ops = {
2882        .carrier_raised = gsm_carrier_raised,
2883        .dtr_rts = gsm_dtr_rts,
2884        .destruct = gsm_dlci_free,
2885};
2886
2887static int gsmtty_install(struct tty_driver *driver, struct tty_struct *tty)
2888{
2889        struct gsm_mux *gsm;
2890        struct gsm_dlci *dlci;
2891        unsigned int line = tty->index;
2892        unsigned int mux = line >> 6;
2893        bool alloc = false;
2894        int ret;
2895
2896        line = line & 0x3F;
2897
2898        if (mux >= MAX_MUX)
2899                return -ENXIO;
2900        /* FIXME: we need to lock gsm_mux for lifetimes of ttys eventually */
2901        if (gsm_mux[mux] == NULL)
2902                return -EUNATCH;
2903        if (line == 0 || line > 61)     /* 62/63 reserved */
2904                return -ECHRNG;
2905        gsm = gsm_mux[mux];
2906        if (gsm->dead)
2907                return -EL2HLT;
2908        /* If DLCI 0 is not yet fully open return an error.
2909        This is ok from a locking
2910        perspective as we don't have to worry about this
2911        if DLCI0 is lost */
2912        if (gsm->dlci[0] && gsm->dlci[0]->state != DLCI_OPEN)
2913                return -EL2NSYNC;
2914        dlci = gsm->dlci[line];
2915        if (dlci == NULL) {
2916                alloc = true;
2917                dlci = gsm_dlci_alloc(gsm, line);
2918        }
2919        if (dlci == NULL)
2920                return -ENOMEM;
2921        ret = tty_port_install(&dlci->port, driver, tty);
2922        if (ret) {
2923                if (alloc)
2924                        dlci_put(dlci);
2925                return ret;
2926        }
2927
2928        tty->driver_data = dlci;
2929
2930        return 0;
2931}
2932
2933static int gsmtty_open(struct tty_struct *tty, struct file *filp)
2934{
2935        struct gsm_dlci *dlci = tty->driver_data;
2936        struct tty_port *port = &dlci->port;
2937
2938        port->count++;
2939        dlci_get(dlci);
2940        dlci_get(dlci->gsm->dlci[0]);
2941        mux_get(dlci->gsm);
2942        tty_port_tty_set(port, tty);
2943
2944        dlci->modem_rx = 0;
2945        /* We could in theory open and close before we wait - eg if we get
2946           a DM straight back. This is ok as that will have caused a hangup */
2947        set_bit(ASYNCB_INITIALIZED, &port->flags);
2948        /* Start sending off SABM messages */
2949        gsm_dlci_begin_open(dlci);
2950        /* And wait for virtual carrier */
2951        return tty_port_block_til_ready(port, tty, filp);
2952}
2953
2954static void gsmtty_close(struct tty_struct *tty, struct file *filp)
2955{
2956        struct gsm_dlci *dlci = tty->driver_data;
2957        struct gsm_mux *gsm;
2958
2959        if (dlci == NULL)
2960                return;
2961        if (dlci->state == DLCI_CLOSED)
2962                return;
2963        mutex_lock(&dlci->mutex);
2964        gsm_destroy_network(dlci);
2965        mutex_unlock(&dlci->mutex);
2966        gsm = dlci->gsm;
2967        if (tty_port_close_start(&dlci->port, tty, filp) == 0)
2968                goto out;
2969        gsm_dlci_begin_close(dlci);
2970        if (test_bit(ASYNCB_INITIALIZED, &dlci->port.flags)) {
2971                if (C_HUPCL(tty))
2972                        tty_port_lower_dtr_rts(&dlci->port);
2973        }
2974        tty_port_close_end(&dlci->port, tty);
2975        tty_port_tty_set(&dlci->port, NULL);
2976out:
2977        dlci_put(dlci);
2978        dlci_put(gsm->dlci[0]);
2979        mux_put(gsm);
2980}
2981
2982static void gsmtty_hangup(struct tty_struct *tty)
2983{
2984        struct gsm_dlci *dlci = tty->driver_data;
2985        if (dlci->state == DLCI_CLOSED)
2986                return;
2987        tty_port_hangup(&dlci->port);
2988        gsm_dlci_begin_close(dlci);
2989}
2990
2991static int gsmtty_write(struct tty_struct *tty, const unsigned char *buf,
2992                                                                    int len)
2993{
2994        int sent;
2995        struct gsm_dlci *dlci = tty->driver_data;
2996        if (dlci->state == DLCI_CLOSED)
2997                return -EINVAL;
2998        /* Stuff the bytes into the fifo queue */
2999        sent = kfifo_in_locked(dlci->fifo, buf, len, &dlci->lock);
3000        /* Need to kick the channel */
3001        gsm_dlci_data_kick(dlci);
3002        return sent;
3003}
3004
3005static int gsmtty_write_room(struct tty_struct *tty)
3006{
3007        struct gsm_dlci *dlci = tty->driver_data;
3008        if (dlci->state == DLCI_CLOSED)
3009                return -EINVAL;
3010        return TX_SIZE - kfifo_len(dlci->fifo);
3011}
3012
3013static int gsmtty_chars_in_buffer(struct tty_struct *tty)
3014{
3015        struct gsm_dlci *dlci = tty->driver_data;
3016        if (dlci->state == DLCI_CLOSED)
3017                return -EINVAL;
3018        return kfifo_len(dlci->fifo);
3019}
3020
3021static void gsmtty_flush_buffer(struct tty_struct *tty)
3022{
3023        struct gsm_dlci *dlci = tty->driver_data;
3024        if (dlci->state == DLCI_CLOSED)
3025                return;
3026        /* Caution needed: If we implement reliable transport classes
3027           then the data being transmitted can't simply be junked once
3028           it has first hit the stack. Until then we can just blow it
3029           away */
3030        kfifo_reset(dlci->fifo);
3031        /* Need to unhook this DLCI from the transmit queue logic */
3032}
3033
3034static void gsmtty_wait_until_sent(struct tty_struct *tty, int timeout)
3035{
3036        /* The FIFO handles the queue so the kernel will do the right
3037           thing waiting on chars_in_buffer before calling us. No work
3038           to do here */
3039}
3040
3041static int gsmtty_tiocmget(struct tty_struct *tty)
3042{
3043        struct gsm_dlci *dlci = tty->driver_data;
3044        if (dlci->state == DLCI_CLOSED)
3045                return -EINVAL;
3046        return dlci->modem_rx;
3047}
3048
3049static int gsmtty_tiocmset(struct tty_struct *tty,
3050        unsigned int set, unsigned int clear)
3051{
3052        struct gsm_dlci *dlci = tty->driver_data;
3053        unsigned int modem_tx = dlci->modem_tx;
3054
3055        if (dlci->state == DLCI_CLOSED)
3056                return -EINVAL;
3057        modem_tx &= ~clear;
3058        modem_tx |= set;
3059
3060        if (modem_tx != dlci->modem_tx) {
3061                dlci->modem_tx = modem_tx;
3062                return gsmtty_modem_update(dlci, 0);
3063        }
3064        return 0;
3065}
3066
3067
3068static int gsmtty_ioctl(struct tty_struct *tty,
3069                        unsigned int cmd, unsigned long arg)
3070{
3071        struct gsm_dlci *dlci = tty->driver_data;
3072        struct gsm_netconfig nc;
3073        int index;
3074
3075        if (dlci->state == DLCI_CLOSED)
3076                return -EINVAL;
3077        switch (cmd) {
3078        case GSMIOC_ENABLE_NET:
3079                if (copy_from_user(&nc, (void __user *)arg, sizeof(nc)))
3080                        return -EFAULT;
3081                nc.if_name[IFNAMSIZ-1] = '\0';
3082                /* return net interface index or error code */
3083                mutex_lock(&dlci->mutex);
3084                index = gsm_create_network(dlci, &nc);
3085                mutex_unlock(&dlci->mutex);
3086                if (copy_to_user((void __user *)arg, &nc, sizeof(nc)))
3087                        return -EFAULT;
3088                return index;
3089        case GSMIOC_DISABLE_NET:
3090                if (!capable(CAP_NET_ADMIN))
3091                        return -EPERM;
3092                mutex_lock(&dlci->mutex);
3093                gsm_destroy_network(dlci);
3094                mutex_unlock(&dlci->mutex);
3095                return 0;
3096        default:
3097                return -ENOIOCTLCMD;
3098        }
3099}
3100
3101static void gsmtty_set_termios(struct tty_struct *tty, struct ktermios *old)
3102{
3103        struct gsm_dlci *dlci = tty->driver_data;
3104        if (dlci->state == DLCI_CLOSED)
3105                return;
3106        /* For the moment its fixed. In actual fact the speed information
3107           for the virtual channel can be propogated in both directions by
3108           the RPN control message. This however rapidly gets nasty as we
3109           then have to remap modem signals each way according to whether
3110           our virtual cable is null modem etc .. */
3111        tty_termios_copy_hw(&tty->termios, old);
3112}
3113
3114static void gsmtty_throttle(struct tty_struct *tty)
3115{
3116        struct gsm_dlci *dlci = tty->driver_data;
3117        if (dlci->state == DLCI_CLOSED)
3118                return;
3119        if (tty->termios.c_cflag & CRTSCTS)
3120                dlci->modem_tx &= ~TIOCM_DTR;
3121        dlci->throttled = 1;
3122        /* Send an MSC with DTR cleared */
3123        gsmtty_modem_update(dlci, 0);
3124}
3125
3126static void gsmtty_unthrottle(struct tty_struct *tty)
3127{
3128        struct gsm_dlci *dlci = tty->driver_data;
3129        if (dlci->state == DLCI_CLOSED)
3130                return;
3131        if (tty->termios.c_cflag & CRTSCTS)
3132                dlci->modem_tx |= TIOCM_DTR;
3133        dlci->throttled = 0;
3134        /* Send an MSC with DTR set */
3135        gsmtty_modem_update(dlci, 0);
3136}
3137
3138static int gsmtty_break_ctl(struct tty_struct *tty, int state)
3139{
3140        struct gsm_dlci *dlci = tty->driver_data;
3141        int encode = 0; /* Off */
3142        if (dlci->state == DLCI_CLOSED)
3143                return -EINVAL;
3144
3145        if (state == -1)        /* "On indefinitely" - we can't encode this
3146                                    properly */
3147                encode = 0x0F;
3148        else if (state > 0) {
3149                encode = state / 200;   /* mS to encoding */
3150                if (encode > 0x0F)
3151                        encode = 0x0F;  /* Best effort */
3152        }
3153        return gsmtty_modem_update(dlci, encode);
3154}
3155
3156
3157/* Virtual ttys for the demux */
3158static const struct tty_operations gsmtty_ops = {
3159        .install                = gsmtty_install,
3160        .open                   = gsmtty_open,
3161        .close                  = gsmtty_close,
3162        .write                  = gsmtty_write,
3163        .write_room             = gsmtty_write_room,
3164        .chars_in_buffer        = gsmtty_chars_in_buffer,
3165        .flush_buffer           = gsmtty_flush_buffer,
3166        .ioctl                  = gsmtty_ioctl,
3167        .throttle               = gsmtty_throttle,
3168        .unthrottle             = gsmtty_unthrottle,
3169        .set_termios            = gsmtty_set_termios,
3170        .hangup                 = gsmtty_hangup,
3171        .wait_until_sent        = gsmtty_wait_until_sent,
3172        .tiocmget               = gsmtty_tiocmget,
3173        .tiocmset               = gsmtty_tiocmset,
3174        .break_ctl              = gsmtty_break_ctl,
3175};
3176
3177
3178
3179static int __init gsm_init(void)
3180{
3181        /* Fill in our line protocol discipline, and register it */
3182        int status = tty_register_ldisc(N_GSM0710, &tty_ldisc_packet);
3183        if (status != 0) {
3184                pr_err("n_gsm: can't register line discipline (err = %d)\n",
3185                                                                status);
3186                return status;
3187        }
3188
3189        gsm_tty_driver = alloc_tty_driver(256);
3190        if (!gsm_tty_driver) {
3191                tty_unregister_ldisc(N_GSM0710);
3192                pr_err("gsm_init: tty allocation failed.\n");
3193                return -EINVAL;
3194        }
3195        gsm_tty_driver->driver_name     = "gsmtty";
3196        gsm_tty_driver->name            = "gsmtty";
3197        gsm_tty_driver->major           = 0;    /* Dynamic */
3198        gsm_tty_driver->minor_start     = 0;
3199        gsm_tty_driver->type            = TTY_DRIVER_TYPE_SERIAL;
3200        gsm_tty_driver->subtype = SERIAL_TYPE_NORMAL;
3201        gsm_tty_driver->flags   = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV
3202                                                | TTY_DRIVER_HARDWARE_BREAK;
3203        gsm_tty_driver->init_termios    = tty_std_termios;
3204        /* Fixme */
3205        gsm_tty_driver->init_termios.c_lflag &= ~ECHO;
3206        tty_set_operations(gsm_tty_driver, &gsmtty_ops);
3207
3208        spin_lock_init(&gsm_mux_lock);
3209
3210        if (tty_register_driver(gsm_tty_driver)) {
3211                put_tty_driver(gsm_tty_driver);
3212                tty_unregister_ldisc(N_GSM0710);
3213                pr_err("gsm_init: tty registration failed.\n");
3214                return -EBUSY;
3215        }
3216        pr_debug("gsm_init: loaded as %d,%d.\n",
3217                        gsm_tty_driver->major, gsm_tty_driver->minor_start);
3218        return 0;
3219}
3220
3221static void __exit gsm_exit(void)
3222{
3223        int status = tty_unregister_ldisc(N_GSM0710);
3224        if (status != 0)
3225                pr_err("n_gsm: can't unregister line discipline (err = %d)\n",
3226                                                                status);
3227        tty_unregister_driver(gsm_tty_driver);
3228        put_tty_driver(gsm_tty_driver);
3229}
3230
3231module_init(gsm_init);
3232module_exit(gsm_exit);
3233
3234
3235MODULE_LICENSE("GPL");
3236MODULE_ALIAS_LDISC(N_GSM0710);
3237
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.