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. Always one byte as we never
 831                           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 gsm->encoding = 0 only.
1745                            In this case it contain the last piece of data
1746                            required to generate final CRC */
1747                gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs);
1748        }
1749        if (gsm->fcs != GOOD_FCS) {
1750                gsm->bad_fcs++;
1751                if (debug & 4)
1752                        pr_debug("BAD FCS %02x\n", gsm->fcs);
1753                return;
1754        }
1755        address = gsm->address >> 1;
1756        if (address >= NUM_DLCI)
1757                goto invalid;
1758
1759        cr = gsm->address & 1;          /* C/R bit */
1760
1761        gsm_print_packet("<--", address, cr, gsm->control, gsm->buf, gsm->len);
1762
1763        cr ^= 1 - gsm->initiator;       /* Flip so 1 always means command */
1764        dlci = gsm->dlci[address];
1765
1766        switch (gsm->control) {
1767        case SABM|PF:
1768                if (cr == 0)
1769                        goto invalid;
1770                if (dlci == NULL)
1771                        dlci = gsm_dlci_alloc(gsm, address);
1772                if (dlci == NULL)
1773                        return;
1774                if (dlci->dead)
1775                        gsm_response(gsm, address, DM);
1776                else {
1777                        gsm_response(gsm, address, UA);
1778                        gsm_dlci_open(dlci);
1779                }
1780                break;
1781        case DISC|PF:
1782                if (cr == 0)
1783                        goto invalid;
1784                if (dlci == NULL || dlci->state == DLCI_CLOSED) {
1785                        gsm_response(gsm, address, DM);
1786                        return;
1787                }
1788                /* Real close complete */
1789                gsm_response(gsm, address, UA);
1790                gsm_dlci_close(dlci);
1791                break;
1792        case UA:
1793        case UA|PF:
1794                if (cr == 0 || dlci == NULL)
1795                        break;
1796                switch (dlci->state) {
1797                case DLCI_CLOSING:
1798                        gsm_dlci_close(dlci);
1799                        break;
1800                case DLCI_OPENING:
1801                        gsm_dlci_open(dlci);
1802                        break;
1803                }
1804                break;
1805        case DM:        /* DM can be valid unsolicited */
1806        case DM|PF:
1807                if (cr)
1808                        goto invalid;
1809                if (dlci == NULL)
1810                        return;
1811                gsm_dlci_close(dlci);
1812                break;
1813        case UI:
1814        case UI|PF:
1815        case UIH:
1816        case UIH|PF:
1817#if 0
1818                if (cr)
1819                        goto invalid;
1820#endif
1821                if (dlci == NULL || dlci->state != DLCI_OPEN) {
1822                        gsm_command(gsm, address, DM|PF);
1823                        return;
1824                }
1825                dlci->data(dlci, gsm->buf, gsm->len);
1826                break;
1827        default:
1828                goto invalid;
1829        }
1830        return;
1831invalid:
1832        gsm->malformed++;
1833        return;
1834}
1835
1836
1837/**
1838 *      gsm0_receive    -       perform processing for non-transparency
1839 *      @gsm: gsm data for this ldisc instance
1840 *      @c: character
1841 *
1842 *      Receive bytes in gsm mode 0
1843 */
1844
1845static void gsm0_receive(struct gsm_mux *gsm, unsigned char c)
1846{
1847        unsigned int len;
1848
1849        switch (gsm->state) {
1850        case GSM_SEARCH:        /* SOF marker */
1851                if (c == GSM0_SOF) {
1852                        gsm->state = GSM_ADDRESS;
1853                        gsm->address = 0;
1854                        gsm->len = 0;
1855                        gsm->fcs = INIT_FCS;
1856                }
1857                break;
1858        case GSM_ADDRESS:       /* Address EA */
1859                gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1860                if (gsm_read_ea(&gsm->address, c))
1861                        gsm->state = GSM_CONTROL;
1862                break;
1863        case GSM_CONTROL:       /* Control Byte */
1864                gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1865                gsm->control = c;
1866                gsm->state = GSM_LEN0;
1867                break;
1868        case GSM_LEN0:          /* Length EA */
1869                gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1870                if (gsm_read_ea(&gsm->len, c)) {
1871                        if (gsm->len > gsm->mru) {
1872                                gsm->bad_size++;
1873                                gsm->state = GSM_SEARCH;
1874                                break;
1875                        }
1876                        gsm->count = 0;
1877                        if (!gsm->len)
1878                                gsm->state = GSM_FCS;
1879                        else
1880                                gsm->state = GSM_DATA;
1881                        break;
1882                }
1883                gsm->state = GSM_LEN1;
1884                break;
1885        case GSM_LEN1:
1886                gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1887                len = c;
1888                gsm->len |= len << 7;
1889                if (gsm->len > gsm->mru) {
1890                        gsm->bad_size++;
1891                        gsm->state = GSM_SEARCH;
1892                        break;
1893                }
1894                gsm->count = 0;
1895                if (!gsm->len)
1896                        gsm->state = GSM_FCS;
1897                else
1898                        gsm->state = GSM_DATA;
1899                break;
1900        case GSM_DATA:          /* Data */
1901                gsm->buf[gsm->count++] = c;
1902                if (gsm->count == gsm->len)
1903                        gsm->state = GSM_FCS;
1904                break;
1905        case GSM_FCS:           /* FCS follows the packet */
1906                gsm->received_fcs = c;
1907                gsm_queue(gsm);
1908                gsm->state = GSM_SSOF;
1909                break;
1910        case GSM_SSOF:
1911                if (c == GSM0_SOF) {
1912                        gsm->state = GSM_SEARCH;
1913                        break;
1914                }
1915                break;
1916        }
1917}
1918
1919/**
1920 *      gsm1_receive    -       perform processing for non-transparency
1921 *      @gsm: gsm data for this ldisc instance
1922 *      @c: character
1923 *
1924 *      Receive bytes in mode 1 (Advanced option)
1925 */
1926
1927static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
1928{
1929        if (c == GSM1_SOF) {
1930                /* EOF is only valid in frame if we have got to the data state
1931                   and received at least one byte (the FCS) */
1932                if (gsm->state == GSM_DATA && gsm->count) {
1933                        /* Extract the FCS */
1934                        gsm->count--;
1935                        gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]);
1936                        gsm->len = gsm->count;
1937                        gsm_queue(gsm);
1938                        gsm->state  = GSM_START;
1939                        return;
1940                }
1941                /* Any partial frame was a runt so go back to start */
1942                if (gsm->state != GSM_START) {
1943                        gsm->malformed++;
1944                        gsm->state = GSM_START;
1945                }
1946                /* A SOF in GSM_START means we are still reading idling or
1947                   framing bytes */
1948                return;
1949        }
1950
1951        if (c == GSM1_ESCAPE) {
1952                gsm->escape = 1;
1953                return;
1954        }
1955
1956        /* Only an unescaped SOF gets us out of GSM search */
1957        if (gsm->state == GSM_SEARCH)
1958                return;
1959
1960        if (gsm->escape) {
1961                c ^= GSM1_ESCAPE_BITS;
1962                gsm->escape = 0;
1963        }
1964        switch (gsm->state) {
1965        case GSM_START:         /* First byte after SOF */
1966                gsm->address = 0;
1967                gsm->state = GSM_ADDRESS;
1968                gsm->fcs = INIT_FCS;
1969                /* Drop through */
1970        case GSM_ADDRESS:       /* Address continuation */
1971                gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1972                if (gsm_read_ea(&gsm->address, c))
1973                        gsm->state = GSM_CONTROL;
1974                break;
1975        case GSM_CONTROL:       /* Control Byte */
1976                gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1977                gsm->control = c;
1978                gsm->count = 0;
1979                gsm->state = GSM_DATA;
1980                break;
1981        case GSM_DATA:          /* Data */
1982                if (gsm->count > gsm->mru) {    /* Allow one for the FCS */
1983                        gsm->state = GSM_OVERRUN;
1984                        gsm->bad_size++;
1985                } else
1986                        gsm->buf[gsm->count++] = c;
1987                break;
1988        case GSM_OVERRUN:       /* Over-long - eg a dropped SOF */
1989                break;
1990        }
1991}
1992
1993/**
1994 *      gsm_error               -       handle tty error
1995 *      @gsm: ldisc data
1996 *      @data: byte received (may be invalid)
1997 *      @flag: error received
1998 *
1999 *      Handle an error in the receipt of data for a frame. Currently we just
2000 *      go back to hunting for a SOF.
2001 *
2002 *      FIXME: better diagnostics ?
2003 */
2004
2005static void gsm_error(struct gsm_mux *gsm,
2006                                unsigned char data, unsigned char flag)
2007{
2008        gsm->state = GSM_SEARCH;
2009        gsm->io_error++;
2010}
2011
2012/**
2013 *      gsm_cleanup_mux         -       generic GSM protocol cleanup
2014 *      @gsm: our mux
2015 *
2016 *      Clean up the bits of the mux which are the same for all framing
2017 *      protocols. Remove the mux from the mux table, stop all the timers
2018 *      and then shut down each device hanging up the channels as we go.
2019 */
2020
2021void gsm_cleanup_mux(struct gsm_mux *gsm)
2022{
2023        int i;
2024        struct gsm_dlci *dlci = gsm->dlci[0];
2025        struct gsm_msg *txq, *ntxq;
2026        struct gsm_control *gc;
2027
2028        gsm->dead = 1;
2029
2030        spin_lock(&gsm_mux_lock);
2031        for (i = 0; i < MAX_MUX; i++) {
2032                if (gsm_mux[i] == gsm) {
2033                        gsm_mux[i] = NULL;
2034                        break;
2035                }
2036        }
2037        spin_unlock(&gsm_mux_lock);
2038        WARN_ON(i == MAX_MUX);
2039
2040        /* In theory disconnecting DLCI 0 is sufficient but for some
2041           modems this is apparently not the case. */
2042        if (dlci) {
2043                gc = gsm_control_send(gsm, CMD_CLD, NULL, 0);
2044                if (gc)
2045                        gsm_control_wait(gsm, gc);
2046        }
2047        del_timer_sync(&gsm->t2_timer);
2048        /* Now we are sure T2 has stopped */
2049        if (dlci) {
2050                dlci->dead = 1;
2051                gsm_dlci_begin_close(dlci);
2052                wait_event_interruptible(gsm->event,
2053                                        dlci->state == DLCI_CLOSED);
2054        }
2055        /* Free up any link layer users */
2056        for (i = 0; i < NUM_DLCI; i++)
2057                if (gsm->dlci[i])
2058                        gsm_dlci_release(gsm->dlci[i]);
2059        /* Now wipe the queues */
2060        list_for_each_entry_safe(txq, ntxq, &gsm->tx_list, list)
2061                kfree(txq);
2062        INIT_LIST_HEAD(&gsm->tx_list);
2063}
2064EXPORT_SYMBOL_GPL(gsm_cleanup_mux);
2065
2066/**
2067 *      gsm_activate_mux        -       generic GSM setup
2068 *      @gsm: our mux
2069 *
2070 *      Set up the bits of the mux which are the same for all framing
2071 *      protocols. Add the mux to the mux table so it can be opened and
2072 *      finally kick off connecting to DLCI 0 on the modem.
2073 */
2074
2075int gsm_activate_mux(struct gsm_mux *gsm)
2076{
2077        struct gsm_dlci *dlci;
2078        int i = 0;
2079
2080        init_timer(&gsm->t2_timer);
2081        gsm->t2_timer.function = gsm_control_retransmit;
2082        gsm->t2_timer.data = (unsigned long)gsm;
2083        init_waitqueue_head(&gsm->event);
2084        spin_lock_init(&gsm->control_lock);
2085        spin_lock_init(&gsm->tx_lock);
2086
2087        if (gsm->encoding == 0)
2088                gsm->receive = gsm0_receive;
2089        else
2090                gsm->receive = gsm1_receive;
2091        gsm->error = gsm_error;
2092
2093        spin_lock(&gsm_mux_lock);
2094        for (i = 0; i < MAX_MUX; i++) {
2095                if (gsm_mux[i] == NULL) {
2096                        gsm->num = i;
2097                        gsm_mux[i] = gsm;
2098                        break;
2099                }
2100        }
2101        spin_unlock(&gsm_mux_lock);
2102        if (i == MAX_MUX)
2103                return -EBUSY;
2104
2105        dlci = gsm_dlci_alloc(gsm, 0);
2106        if (dlci == NULL)
2107                return -ENOMEM;
2108        gsm->dead = 0;          /* Tty opens are now permissible */
2109        return 0;
2110}
2111EXPORT_SYMBOL_GPL(gsm_activate_mux);
2112
2113/**
2114 *      gsm_free_mux            -       free up a mux
2115 *      @mux: mux to free
2116 *
2117 *      Dispose of allocated resources for a dead mux
2118 */
2119void gsm_free_mux(struct gsm_mux *gsm)
2120{
2121        kfree(gsm->txframe);
2122        kfree(gsm->buf);
2123        kfree(gsm);
2124}
2125EXPORT_SYMBOL_GPL(gsm_free_mux);
2126
2127/**
2128 *      gsm_free_muxr           -       free up a mux
2129 *      @mux: mux to free
2130 *
2131 *      Dispose of allocated resources for a dead mux
2132 */
2133static void gsm_free_muxr(struct kref *ref)
2134{
2135        struct gsm_mux *gsm = container_of(ref, struct gsm_mux, ref);
2136        gsm_free_mux(gsm);
2137}
2138
2139static inline void mux_get(struct gsm_mux *gsm)
2140{
2141        kref_get(&gsm->ref);
2142}
2143
2144static inline void mux_put(struct gsm_mux *gsm)
2145{
2146        kref_put(&gsm->ref, gsm_free_muxr);
2147}
2148
2149/**
2150 *      gsm_alloc_mux           -       allocate a mux
2151 *
2152 *      Creates a new mux ready for activation.
2153 */
2154
2155struct gsm_mux *gsm_alloc_mux(void)
2156{
2157        struct gsm_mux *gsm = kzalloc(sizeof(struct gsm_mux), GFP_KERNEL);
2158        if (gsm == NULL)
2159                return NULL;
2160        gsm->buf = kmalloc(MAX_MRU + 1, GFP_KERNEL);
2161        if (gsm->buf == NULL) {
2162                kfree(gsm);
2163                return NULL;
2164        }
2165        gsm->txframe = kmalloc(2 * MAX_MRU + 2, GFP_KERNEL);
2166        if (gsm->txframe == NULL) {
2167                kfree(gsm->buf);
2168                kfree(gsm);
2169                return NULL;
2170        }
2171        spin_lock_init(&gsm->lock);
2172        kref_init(&gsm->ref);
2173        INIT_LIST_HEAD(&gsm->tx_list);
2174
2175        gsm->t1 = T1;
2176        gsm->t2 = T2;
2177        gsm->n2 = N2;
2178        gsm->ftype = UIH;
2179        gsm->adaption = 1;
2180        gsm->encoding = 1;
2181        gsm->mru = 64;  /* Default to encoding 1 so these should be 64 */
2182        gsm->mtu = 64;
2183        gsm->dead = 1;  /* Avoid early tty opens */
2184
2185        return gsm;
2186}
2187EXPORT_SYMBOL_GPL(gsm_alloc_mux);
2188
2189/**
2190 *      gsmld_output            -       write to link
2191 *      @gsm: our mux
2192 *      @data: bytes to output
2193 *      @len: size
2194 *
2195 *      Write a block of data from the GSM mux to the data channel. This
2196 *      will eventually be serialized from above but at the moment isn't.
2197 */
2198
2199static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len)
2200{
2201        if (tty_write_room(gsm->tty) < len) {
2202                set_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
2203                return -ENOSPC;
2204        }
2205        if (debug & 4)
2206                print_hex_dump_bytes("gsmld_output: ", DUMP_PREFIX_OFFSET,
2207                                     data, len);
2208        gsm->tty->ops->write(gsm->tty, data, len);
2209        return len;
2210}
2211
2212/**
2213 *      gsmld_attach_gsm        -       mode set up
2214 *      @tty: our tty structure
2215 *      @gsm: our mux
2216 *
2217 *      Set up the MUX for basic mode and commence connecting to the
2218 *      modem. Currently called from the line discipline set up but
2219 *      will need moving to an ioctl path.
2220 */
2221
2222static int gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2223{
2224        int ret, i;
2225        int base = gsm->num << 6; /* Base for this MUX */
2226
2227        gsm->tty = tty_kref_get(tty);
2228        gsm->output = gsmld_output;
2229        ret =  gsm_activate_mux(gsm);
2230        if (ret != 0)
2231                tty_kref_put(gsm->tty);
2232        else {
2233                /* Don't register device 0 - this is the control channel and not
2234                   a usable tty interface */
2235                for (i = 1; i < NUM_DLCI; i++)
2236                        tty_register_device(gsm_tty_driver, base + i, NULL);
2237        }
2238        return ret;
2239}
2240
2241
2242/**
2243 *      gsmld_detach_gsm        -       stop doing 0710 mux
2244 *      @tty: tty attached to the mux
2245 *      @gsm: mux
2246 *
2247 *      Shutdown and then clean up the resources used by the line discipline
2248 */
2249
2250static void gsmld_detach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2251{
2252        int i;
2253        int base = gsm->num << 6; /* Base for this MUX */
2254
2255        WARN_ON(tty != gsm->tty);
2256        for (i = 1; i < NUM_DLCI; i++)
2257                tty_unregister_device(gsm_tty_driver, base + i);
2258        gsm_cleanup_mux(gsm);
2259        tty_kref_put(gsm->tty);
2260        gsm->tty = NULL;
2261}
2262
2263static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp,
2264                              char *fp, int count)
2265{
2266        struct gsm_mux *gsm = tty->disc_data;
2267        const unsigned char *dp;
2268        char *f;
2269        int i;
2270        char buf[64];
2271        char flags;
2272
2273        if (debug & 4)
2274                print_hex_dump_bytes("gsmld_receive: ", DUMP_PREFIX_OFFSET,
2275                                     cp, count);
2276
2277        for (i = count, dp = cp, f = fp; i; i--, dp++) {
2278                flags = *f++;
2279                switch (flags) {
2280                case TTY_NORMAL:
2281                        gsm->receive(gsm, *dp);
2282                        break;
2283                case TTY_OVERRUN:
2284                case TTY_BREAK:
2285                case TTY_PARITY:
2286                case TTY_FRAME:
2287                        gsm->error(gsm, *dp, flags);
2288                        break;
2289                default:
2290                        WARN_ONCE(1, "%s: unknown flag %d\n",
2291                               tty_name(tty, buf), flags);
2292                        break;
2293                }
2294        }
2295        /* FASYNC if needed ? */
2296        /* If clogged call tty_throttle(tty); */
2297}
2298
2299/**
2300 *      gsmld_chars_in_buffer   -       report available bytes
2301 *      @tty: tty device
2302 *
2303 *      Report the number of characters buffered to be delivered to user
2304 *      at this instant in time.
2305 *
2306 *      Locking: gsm lock
2307 */
2308
2309static ssize_t gsmld_chars_in_buffer(struct tty_struct *tty)
2310{
2311        return 0;
2312}
2313
2314/**
2315 *      gsmld_flush_buffer      -       clean input queue
2316 *      @tty:   terminal device
2317 *
2318 *      Flush the input buffer. Called when the line discipline is
2319 *      being closed, when the tty layer wants the buffer flushed (eg
2320 *      at hangup).
2321 */
2322
2323static void gsmld_flush_buffer(struct tty_struct *tty)
2324{
2325}
2326
2327/**
2328 *      gsmld_close             -       close the ldisc for this tty
2329 *      @tty: device
2330 *
2331 *      Called from the terminal layer when this line discipline is
2332 *      being shut down, either because of a close or becsuse of a
2333 *      discipline change. The function will not be called while other
2334 *      ldisc methods are in progress.
2335 */
2336
2337static void gsmld_close(struct tty_struct *tty)
2338{
2339        struct gsm_mux *gsm = tty->disc_data;
2340
2341        gsmld_detach_gsm(tty, gsm);
2342
2343        gsmld_flush_buffer(tty);
2344        /* Do other clean up here */
2345        mux_put(gsm);
2346}
2347
2348/**
2349 *      gsmld_open              -       open an ldisc
2350 *      @tty: terminal to open
2351 *
2352 *      Called when this line discipline is being attached to the
2353 *      terminal device. Can sleep. Called serialized so that no
2354 *      other events will occur in parallel. No further open will occur
2355 *      until a close.
2356 */
2357
2358static int gsmld_open(struct tty_struct *tty)
2359{
2360        struct gsm_mux *gsm;
2361
2362        if (tty->ops->write == NULL)
2363                return -EINVAL;
2364
2365        /* Attach our ldisc data */
2366        gsm = gsm_alloc_mux();
2367        if (gsm == NULL)
2368                return -ENOMEM;
2369
2370        tty->disc_data = gsm;
2371        tty->receive_room = 65536;
2372
2373        /* Attach the initial passive connection */
2374        gsm->encoding = 1;
2375        return gsmld_attach_gsm(tty, gsm);
2376}
2377
2378/**
2379 *      gsmld_write_wakeup      -       asynchronous I/O notifier
2380 *      @tty: tty device
2381 *
2382 *      Required for the ptys, serial driver etc. since processes
2383 *      that attach themselves to the master and rely on ASYNC
2384 *      IO must be woken up
2385 */
2386
2387static void gsmld_write_wakeup(struct tty_struct *tty)
2388{
2389        struct gsm_mux *gsm = tty->disc_data;
2390        unsigned long flags;
2391
2392        /* Queue poll */
2393        clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2394        spin_lock_irqsave(&gsm->tx_lock, flags);
2395        gsm_data_kick(gsm);
2396        if (gsm->tx_bytes < TX_THRESH_LO) {
2397                gsm_dlci_data_sweep(gsm);
2398        }
2399        spin_unlock_irqrestore(&gsm->tx_lock, flags);
2400}
2401
2402/**
2403 *      gsmld_read              -       read function for tty
2404 *      @tty: tty device
2405 *      @file: file object
2406 *      @buf: userspace buffer pointer
2407 *      @nr: size of I/O
2408 *
2409 *      Perform reads for the line discipline. We are guaranteed that the
2410 *      line discipline will not be closed under us but we may get multiple
2411 *      parallel readers and must handle this ourselves. We may also get
2412 *      a hangup. Always called in user context, may sleep.
2413 *
2414 *      This code must be sure never to sleep through a hangup.
2415 */
2416
2417static ssize_t gsmld_read(struct tty_struct *tty, struct file *file,
2418                         unsigned char __user *buf, size_t nr)
2419{
2420        return -EOPNOTSUPP;
2421}
2422
2423/**
2424 *      gsmld_write             -       write function for tty
2425 *      @tty: tty device
2426 *      @file: file object
2427 *      @buf: userspace buffer pointer
2428 *      @nr: size of I/O
2429 *
2430 *      Called when the owner of the device wants to send a frame
2431 *      itself (or some other control data). The data is transferred
2432 *      as-is and must be properly framed and checksummed as appropriate
2433 *      by userspace. Frames are either sent whole or not at all as this
2434 *      avoids pain user side.
2435 */
2436
2437static ssize_t gsmld_write(struct tty_struct *tty, struct file *file,
2438                           const unsigned char *buf, size_t nr)
2439{
2440        int space = tty_write_room(tty);
2441        if (space >= nr)
2442                return tty->ops->write(tty, buf, nr);
2443        set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2444        return -ENOBUFS;
2445}
2446
2447/**
2448 *      gsmld_poll              -       poll method for N_GSM0710
2449 *      @tty: terminal device
2450 *      @file: file accessing it
2451 *      @wait: poll table
2452 *
2453 *      Called when the line discipline is asked to poll() for data or
2454 *      for special events. This code is not serialized with respect to
2455 *      other events save open/close.
2456 *
2457 *      This code must be sure never to sleep through a hangup.
2458 *      Called without the kernel lock held - fine
2459 */
2460
2461static unsigned int gsmld_poll(struct tty_struct *tty, struct file *file,
2462                                                        poll_table *wait)
2463{
2464        unsigned int mask = 0;
2465        struct gsm_mux *gsm = tty->disc_data;
2466
2467        poll_wait(file, &tty->read_wait, wait);
2468        poll_wait(file, &tty->write_wait, wait);
2469        if (tty_hung_up_p(file))
2470                mask |= POLLHUP;
2471        if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0)
2472                mask |= POLLOUT | POLLWRNORM;
2473        if (gsm->dead)
2474                mask |= POLLHUP;
2475        return mask;
2476}
2477
2478static int gsmld_config(struct tty_struct *tty, struct gsm_mux *gsm,
2479                                                        struct gsm_config *c)
2480{
2481        int need_close = 0;
2482        int need_restart = 0;
2483
2484        /* Stuff we don't support yet - UI or I frame transport, windowing */
2485        if ((c->adaption != 1 && c->adaption != 2) || c->k)
2486                return -EOPNOTSUPP;
2487        /* Check the MRU/MTU range looks sane */
2488        if (c->mru > MAX_MRU || c->mtu > MAX_MTU || c->mru < 8 || c->mtu < 8)
2489                return -EINVAL;
2490        if (c->n2 < 3)
2491                return -EINVAL;
2492        if (c->encapsulation > 1)       /* Basic, advanced, no I */
2493                return -EINVAL;
2494        if (c->initiator > 1)
2495                return -EINVAL;
2496        if (c->i == 0 || c->i > 2)      /* UIH and UI only */
2497                return -EINVAL;
2498        /*
2499         *      See what is needed for reconfiguration
2500         */
2501
2502        /* Timing fields */
2503        if (c->t1 != 0 && c->t1 != gsm->t1)
2504                need_restart = 1;
2505        if (c->t2 != 0 && c->t2 != gsm->t2)
2506                need_restart = 1;
2507        if (c->encapsulation != gsm->encoding)
2508                need_restart = 1;
2509        if (c->adaption != gsm->adaption)
2510                need_restart = 1;
2511        /* Requires care */
2512        if (c->initiator != gsm->initiator)
2513                need_close = 1;
2514        if (c->mru != gsm->mru)
2515                need_restart = 1;
2516        if (c->mtu != gsm->mtu)
2517                need_restart = 1;
2518
2519        /*
2520         *      Close down what is needed, restart and initiate the new
2521         *      configuration
2522         */
2523
2524        if (need_close || need_restart) {
2525                gsm_dlci_begin_close(gsm->dlci[0]);
2526                /* This will timeout if the link is down due to N2 expiring */
2527                wait_event_interruptible(gsm->event,
2528                                gsm->dlci[0]->state == DLCI_CLOSED);
2529                if (signal_pending(current))
2530                        return -EINTR;
2531        }
2532        if (need_restart)
2533                gsm_cleanup_mux(gsm);
2534
2535        gsm->initiator = c->initiator;
2536        gsm->mru = c->mru;
2537        gsm->mtu = c->mtu;
2538        gsm->encoding = c->encapsulation;
2539        gsm->adaption = c->adaption;
2540        gsm->n2 = c->n2;
2541
2542        if (c->i == 1)
2543                gsm->ftype = UIH;
2544        else if (c->i == 2)
2545                gsm->ftype = UI;
2546
2547        if (c->t1)
2548                gsm->t1 = c->t1;
2549        if (c->t2)
2550                gsm->t2 = c->t2;
2551
2552        /* FIXME: We need to separate activation/deactivation from adding
2553           and removing from the mux array */
2554        if (need_restart)
2555                gsm_activate_mux(gsm);
2556        if (gsm->initiator && need_close)
2557                gsm_dlci_begin_open(gsm->dlci[0]);
2558        return 0;
2559}
2560
2561static int gsmld_ioctl(struct tty_struct *tty, struct file *file,
2562                       unsigned int cmd, unsigned long arg)
2563{
2564        struct gsm_config c;
2565        struct gsm_mux *gsm = tty->disc_data;
2566
2567        switch (cmd) {
2568        case GSMIOC_GETCONF:
2569                memset(&c, 0, sizeof(c));
2570                c.adaption = gsm->adaption;
2571                c.encapsulation = gsm->encoding;
2572                c.initiator = gsm->initiator;
2573                c.t1 = gsm->t1;
2574                c.t2 = gsm->t2;
2575                c.t3 = 0;       /* Not supported */
2576                c.n2 = gsm->n2;
2577                if (gsm->ftype == UIH)
2578                        c.i = 1;
2579                else
2580                        c.i = 2;
2581                pr_debug("Ftype %d i %d\n", gsm->ftype, c.i);
2582                c.mru = gsm->mru;
2583                c.mtu = gsm->mtu;
2584                c.k = 0;
2585                if (copy_to_user((void *)arg, &c, sizeof(c)))
2586                        return -EFAULT;
2587                return 0;
2588        case GSMIOC_SETCONF:
2589                if (copy_from_user(&c, (void *)arg, sizeof(c)))
2590                        return -EFAULT;
2591                return gsmld_config(tty, gsm, &c);
2592        default:
2593                return n_tty_ioctl_helper(tty, file, cmd, arg);
2594        }
2595}
2596
2597/*
2598 *      Network interface
2599 *
2600 */
2601
2602static int gsm_mux_net_open(struct net_device *net)
2603{
2604        pr_debug("%s called\n", __func__);
2605        netif_start_queue(net);
2606        return 0;
2607}
2608
2609static int gsm_mux_net_close(struct net_device *net)
2610{
2611        netif_stop_queue(net);
2612        return 0;
2613}
2614
2615static struct net_device_stats *gsm_mux_net_get_stats(struct net_device *net)
2616{
2617        return &((struct gsm_mux_net *)netdev_priv(net))->stats;
2618}
2619static void dlci_net_free(struct gsm_dlci *dlci)
2620{
2621        if (!dlci->net) {
2622                WARN_ON(1);
2623                return;
2624        }
2625        dlci->adaption = dlci->prev_adaption;
2626        dlci->data = dlci->prev_data;
2627        free_netdev(dlci->net);
2628        dlci->net = NULL;
2629}
2630static void net_free(struct kref *ref)
2631{
2632        struct gsm_mux_net *mux_net;
2633        struct gsm_dlci *dlci;
2634
2635        mux_net = container_of(ref, struct gsm_mux_net, ref);
2636        dlci = mux_net->dlci;
2637
2638        if (dlci->net) {
2639                unregister_netdev(dlci->net);
2640                dlci_net_free(dlci);
2641        }
2642}
2643
2644static inline void muxnet_get(struct gsm_mux_net *mux_net)
2645{
2646        kref_get(&mux_net->ref);
2647}
2648
2649static inline void muxnet_put(struct gsm_mux_net *mux_net)
2650{
2651        kref_put(&mux_net->ref, net_free);
2652}
2653
2654static int gsm_mux_net_start_xmit(struct sk_buff *skb,
2655                                      struct net_device *net)
2656{
2657        struct gsm_mux_net *mux_net = (struct gsm_mux_net *)netdev_priv(net);
2658        struct gsm_dlci *dlci = mux_net->dlci;
2659        muxnet_get(mux_net);
2660
2661        skb_queue_head(&dlci->skb_list, skb);
2662        STATS(net).tx_packets++;
2663        STATS(net).tx_bytes += skb->len;
2664        gsm_dlci_data_kick(dlci);
2665        /* And tell the kernel when the last transmit started. */
2666        net->trans_start = jiffies;
2667        muxnet_put(mux_net);
2668        return NETDEV_TX_OK;
2669}
2670
2671/* called when a packet did not ack after watchdogtimeout */
2672static void gsm_mux_net_tx_timeout(struct net_device *net)
2673{
2674        /* Tell syslog we are hosed. */
2675        dev_dbg(&net->dev, "Tx timed out.\n");
2676
2677        /* Update statistics */
2678        STATS(net).tx_errors++;
2679}
2680
2681static void gsm_mux_rx_netchar(struct gsm_dlci *dlci,
2682                                   unsigned char *in_buf, int size)
2683{
2684        struct net_device *net = dlci->net;
2685        struct sk_buff *skb;
2686        struct gsm_mux_net *mux_net = (struct gsm_mux_net *)netdev_priv(net);
2687        muxnet_get(mux_net);
2688
2689        /* Allocate an sk_buff */
2690        skb = dev_alloc_skb(size + NET_IP_ALIGN);
2691        if (!skb) {
2692                /* We got no receive buffer. */
2693                STATS(net).rx_dropped++;
2694                muxnet_put(mux_net);
2695                return;
2696        }
2697        skb_reserve(skb, NET_IP_ALIGN);
2698        memcpy(skb_put(skb, size), in_buf, size);
2699
2700        skb->dev = net;
2701        skb->protocol = __constant_htons(ETH_P_IP);
2702
2703        /* Ship it off to the kernel */
2704        netif_rx(skb);
2705
2706        /* update out statistics */
2707        STATS(net).rx_packets++;
2708        STATS(net).rx_bytes += size;
2709        muxnet_put(mux_net);
2710        return;
2711}
2712
2713int gsm_change_mtu(struct net_device *net, int new_mtu)
2714{
2715        struct gsm_mux_net *mux_net = (struct gsm_mux_net *)netdev_priv(net);
2716        if ((new_mtu < 8) || (new_mtu > mux_net->dlci->gsm->mtu))
2717                return -EINVAL;
2718        net->mtu = new_mtu;
2719        return 0;
2720}
2721
2722static void gsm_mux_net_init(struct net_device *net)
2723{
2724        static const struct net_device_ops gsm_netdev_ops = {
2725                .ndo_open               = gsm_mux_net_open,
2726                .ndo_stop               = gsm_mux_net_close,
2727                .ndo_start_xmit         = gsm_mux_net_start_xmit,
2728                .ndo_tx_timeout         = gsm_mux_net_tx_timeout,
2729                .ndo_get_stats          = gsm_mux_net_get_stats,
2730                .ndo_change_mtu         = gsm_change_mtu,
2731        };
2732
2733        net->netdev_ops = &gsm_netdev_ops;
2734
2735        /* fill in the other fields */
2736        net->watchdog_timeo = GSM_NET_TX_TIMEOUT;
2737        net->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
2738        net->type = ARPHRD_NONE;
2739        net->tx_queue_len = 10;
2740}
2741
2742
2743/* caller holds the dlci mutex */
2744static void gsm_destroy_network(struct gsm_dlci *dlci)
2745{
2746        struct gsm_mux_net *mux_net;
2747
2748        pr_debug("destroy network interface");
2749        if (!dlci->net)
2750                return;
2751        mux_net = (struct gsm_mux_net *)netdev_priv(dlci->net);
2752        muxnet_put(mux_net);
2753}
2754
2755
2756/* caller holds the dlci mutex */
2757static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc)
2758{
2759        char *netname;
2760        int retval = 0;
2761        struct net_device *net;
2762        struct gsm_mux_net *mux_net;
2763
2764        if (!capable(CAP_NET_ADMIN))
2765                return -EPERM;
2766
2767        /* Already in a non tty mode */
2768        if (dlci->adaption > 2)
2769                return -EBUSY;
2770
2771        if (nc->protocol != htons(ETH_P_IP))
2772                return -EPROTONOSUPPORT;
2773
2774        if (nc->adaption != 3 && nc->adaption != 4)
2775                return -EPROTONOSUPPORT;
2776
2777        pr_debug("create network interface");
2778
2779        netname = "gsm%d";
2780        if (nc->if_name[0] != '\0')
2781                netname = nc->if_name;
2782        net = alloc_netdev(sizeof(struct gsm_mux_net),
2783                        netname,
2784                        gsm_mux_net_init);
2785        if (!net) {
2786                pr_err("alloc_netdev failed");
2787                return -ENOMEM;
2788        }
2789        net->mtu = dlci->gsm->mtu;
2790        mux_net = (struct gsm_mux_net *)netdev_priv(net);
2791        mux_net->dlci = dlci;
2792        kref_init(&mux_net->ref);
2793        strncpy(nc->if_name, net->name, IFNAMSIZ); /* return net name */
2794
2795        /* reconfigure dlci for network */
2796        dlci->prev_adaption = dlci->adaption;
2797        dlci->prev_data = dlci->data;
2798        dlci->adaption = nc->adaption;
2799        dlci->data = gsm_mux_rx_netchar;
2800        dlci->net = net;
2801
2802        pr_debug("register netdev");
2803        retval = register_netdev(net);
2804        if (retval) {
2805                pr_err("network register fail %d\n", retval);
2806                dlci_net_free(dlci);
2807                return retval;
2808        }
2809        return net->ifindex;    /* return network index */
2810}
2811
2812/* Line discipline for real tty */
2813struct tty_ldisc_ops tty_ldisc_packet = {
2814        .owner           = THIS_MODULE,
2815        .magic           = TTY_LDISC_MAGIC,
2816        .name            = "n_gsm",
2817        .open            = gsmld_open,
2818        .close           = gsmld_close,
2819        .flush_buffer    = gsmld_flush_buffer,
2820        .chars_in_buffer = gsmld_chars_in_buffer,
2821        .read            = gsmld_read,
2822        .write           = gsmld_write,
2823        .ioctl           = gsmld_ioctl,
2824        .poll            = gsmld_poll,
2825        .receive_buf     = gsmld_receive_buf,
2826        .write_wakeup    = gsmld_write_wakeup
2827};
2828
2829/*
2830 *      Virtual tty side
2831 */
2832
2833#define TX_SIZE         512
2834
2835static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk)
2836{
2837        u8 modembits[5];
2838        struct gsm_control *ctrl;
2839        int len = 2;
2840
2841        if (brk)
2842                len++;
2843
2844        modembits[0] = len << 1 | EA;           /* Data bytes */
2845        modembits[1] = dlci->addr << 2 | 3;     /* DLCI, EA, 1 */
2846        modembits[2] = gsm_encode_modem(dlci) << 1 | EA;
2847        if (brk)
2848                modembits[3] = brk << 4 | 2 | EA;       /* Valid, EA */
2849        ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len + 1);
2850        if (ctrl == NULL)
2851                return -ENOMEM;
2852        return gsm_control_wait(dlci->gsm, ctrl);
2853}
2854
2855static int gsm_carrier_raised(struct tty_port *port)
2856{
2857        struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2858        /* Not yet open so no carrier info */
2859        if (dlci->state != DLCI_OPEN)
2860                return 0;
2861        if (debug & 2)
2862                return 1;
2863        return dlci->modem_rx & TIOCM_CD;
2864}
2865
2866static void gsm_dtr_rts(struct tty_port *port, int onoff)
2867{
2868        struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2869        unsigned int modem_tx = dlci->modem_tx;
2870        if (onoff)
2871                modem_tx |= TIOCM_DTR | TIOCM_RTS;
2872        else
2873                modem_tx &= ~(TIOCM_DTR | TIOCM_RTS);
2874        if (modem_tx != dlci->modem_tx) {
2875                dlci->modem_tx = modem_tx;
2876                gsmtty_modem_update(dlci, 0);
2877        }
2878}
2879
2880static const struct tty_port_operations gsm_port_ops = {
2881        .carrier_raised = gsm_carrier_raised,
2882        .dtr_rts = gsm_dtr_rts,
2883        .destruct = gsm_dlci_free,
2884};
2885
2886static int gsmtty_install(struct tty_driver *driver, struct tty_struct *tty)
2887{
2888        struct gsm_mux *gsm;
2889        struct gsm_dlci *dlci;
2890        unsigned int line = tty->index;
2891        unsigned int mux = line >> 6;
2892        bool alloc = false;
2893        int ret;
2894
2895        line = line & 0x3F;
2896
2897        if (mux >= MAX_MUX)
2898                return -ENXIO;
2899        /* FIXME: we need to lock gsm_mux for lifetimes of ttys eventually */
2900        if (gsm_mux[mux] == NULL)
2901                return -EUNATCH;
2902        if (line == 0 || line > 61)     /* 62/63 reserved */
2903                return -ECHRNG;
2904        gsm = gsm_mux[mux];
2905        if (gsm->dead)
2906                return -EL2HLT;
2907        /* If DLCI 0 is not yet fully open return an error. This is ok from a locking
2908           perspective as we don't have to worry about this if DLCI0 is lost */
2909        if (gsm->dlci[0] && gsm->dlci[0]->state != DLCI_OPEN) 
2910                return -EL2NSYNC;
2911        dlci = gsm->dlci[line];
2912        if (dlci == NULL) {
2913                alloc = true;
2914                dlci = gsm_dlci_alloc(gsm, line);
2915        }
2916        if (dlci == NULL)
2917                return -ENOMEM;
2918        ret = tty_port_install(&dlci->port, driver, tty);
2919        if (ret) {
2920                if (alloc)
2921                        dlci_put(dlci);
2922                return ret;
2923        }
2924
2925        tty->driver_data = dlci;
2926
2927        return 0;
2928}
2929
2930static int gsmtty_open(struct tty_struct *tty, struct file *filp)
2931{
2932        struct gsm_dlci *dlci = tty->driver_data;
2933        struct tty_port *port = &dlci->port;
2934
2935        port->count++;
2936        dlci_get(dlci);
2937        dlci_get(dlci->gsm->dlci[0]);
2938        mux_get(dlci->gsm);
2939        tty_port_tty_set(port, tty);
2940
2941        dlci->modem_rx = 0;
2942        /* We could in theory open and close before we wait - eg if we get
2943           a DM straight back. This is ok as that will have caused a hangup */
2944        set_bit(ASYNCB_INITIALIZED, &port->flags);
2945        /* Start sending off SABM messages */
2946        gsm_dlci_begin_open(dlci);
2947        /* And wait for virtual carrier */
2948        return tty_port_block_til_ready(port, tty, filp);
2949}
2950
2951static void gsmtty_close(struct tty_struct *tty, struct file *filp)
2952{
2953        struct gsm_dlci *dlci = tty->driver_data;
2954        struct gsm_mux *gsm;
2955
2956        if (dlci == NULL)
2957                return;
2958        if (dlci->state == DLCI_CLOSED)
2959                return;
2960        mutex_lock(&dlci->mutex);
2961        gsm_destroy_network(dlci);
2962        mutex_unlock(&dlci->mutex);
2963        gsm = dlci->gsm;
2964        if (tty_port_close_start(&dlci->port, tty, filp) == 0)
2965                goto out;
2966        gsm_dlci_begin_close(dlci);
2967        if (test_bit(ASYNCB_INITIALIZED, &dlci->port.flags)) {
2968                if (C_HUPCL(tty))
2969                        tty_port_lower_dtr_rts(&dlci->port);
2970        }
2971        tty_port_close_end(&dlci->port, tty);
2972        tty_port_tty_set(&dlci->port, NULL);
2973out:
2974        dlci_put(dlci);
2975        dlci_put(gsm->dlci[0]);
2976        mux_put(gsm);
2977}
2978
2979static void gsmtty_hangup(struct tty_struct *tty)
2980{
2981        struct gsm_dlci *dlci = tty->driver_data;
2982        if (dlci->state == DLCI_CLOSED)
2983                return;
2984        tty_port_hangup(&dlci->port);
2985        gsm_dlci_begin_close(dlci);
2986}
2987
2988static int gsmtty_write(struct tty_struct *tty, const unsigned char *buf,
2989                                                                    int len)
2990{
2991        int sent;
2992        struct gsm_dlci *dlci = tty->driver_data;
2993        if (dlci->state == DLCI_CLOSED)
2994                return -EINVAL;
2995        /* Stuff the bytes into the fifo queue */
2996        sent = kfifo_in_locked(dlci->fifo, buf, len, &dlci->lock);
2997        /* Need to kick the channel */
2998        gsm_dlci_data_kick(dlci);
2999        return sent;
3000}
3001
3002static int gsmtty_write_room(struct tty_struct *tty)
3003{
3004        struct gsm_dlci *dlci = tty->driver_data;
3005        if (dlci->state == DLCI_CLOSED)
3006                return -EINVAL;
3007        return TX_SIZE - kfifo_len(dlci->fifo);
3008}
3009
3010static int gsmtty_chars_in_buffer(struct tty_struct *tty)
3011{
3012        struct gsm_dlci *dlci = tty->driver_data;
3013        if (dlci->state == DLCI_CLOSED)
3014                return -EINVAL;
3015        return kfifo_len(dlci->fifo);
3016}
3017
3018static void gsmtty_flush_buffer(struct tty_struct *tty)
3019{
3020        struct gsm_dlci *dlci = tty->driver_data;
3021        if (dlci->state == DLCI_CLOSED)
3022                return;
3023        /* Caution needed: If we implement reliable transport classes
3024           then the data being transmitted can't simply be junked once
3025           it has first hit the stack. Until then we can just blow it
3026           away */
3027        kfifo_reset(dlci->fifo);
3028        /* Need to unhook this DLCI from the transmit queue logic */
3029}
3030
3031static void gsmtty_wait_until_sent(struct tty_struct *tty, int timeout)
3032{
3033        /* The FIFO handles the queue so the kernel will do the right
3034           thing waiting on chars_in_buffer before calling us. No work
3035           to do here */
3036}
3037
3038static int gsmtty_tiocmget(struct tty_struct *tty)
3039{
3040        struct gsm_dlci *dlci = tty->driver_data;
3041        if (dlci->state == DLCI_CLOSED)
3042                return -EINVAL;
3043        return dlci->modem_rx;
3044}
3045
3046static int gsmtty_tiocmset(struct tty_struct *tty,
3047        unsigned int set, unsigned int clear)
3048{
3049        struct gsm_dlci *dlci = tty->driver_data;
3050        unsigned int modem_tx = dlci->modem_tx;
3051
3052        if (dlci->state == DLCI_CLOSED)
3053                return -EINVAL;
3054        modem_tx &= ~clear;
3055        modem_tx |= set;
3056
3057        if (modem_tx != dlci->modem_tx) {
3058                dlci->modem_tx = modem_tx;
3059                return gsmtty_modem_update(dlci, 0);
3060        }
3061        return 0;
3062}
3063
3064
3065static int gsmtty_ioctl(struct tty_struct *tty,
3066                        unsigned int cmd, unsigned long arg)
3067{
3068        struct gsm_dlci *dlci = tty->driver_data;
3069        struct gsm_netconfig nc;
3070        int index;
3071
3072        if (dlci->state == DLCI_CLOSED)
3073                return -EINVAL;
3074        switch (cmd) {
3075        case GSMIOC_ENABLE_NET:
3076                if (copy_from_user(&nc, (void __user *)arg, sizeof(nc)))
3077                        return -EFAULT;
3078                nc.if_name[IFNAMSIZ-1] = '\0';
3079                /* return net interface index or error code */
3080                mutex_lock(&dlci->mutex);
3081                index = gsm_create_network(dlci, &nc);
3082                mutex_unlock(&dlci->mutex);
3083                if (copy_to_user((void __user *)arg, &nc, sizeof(nc)))
3084                        return -EFAULT;
3085                return index;
3086        case GSMIOC_DISABLE_NET:
3087                if (!capable(CAP_NET_ADMIN))
3088                        return -EPERM;
3089                mutex_lock(&dlci->mutex);
3090                gsm_destroy_network(dlci);
3091                mutex_unlock(&dlci->mutex);
3092                return 0;
3093        default:
3094                return -ENOIOCTLCMD;
3095        }
3096}
3097
3098static void gsmtty_set_termios(struct tty_struct *tty, struct ktermios *old)
3099{
3100        struct gsm_dlci *dlci = tty->driver_data;
3101        if (dlci->state == DLCI_CLOSED)
3102                return;
3103        /* For the moment its fixed. In actual fact the speed information
3104           for the virtual channel can be propogated in both directions by
3105           the RPN control message. This however rapidly gets nasty as we
3106           then have to remap modem signals each way according to whether
3107           our virtual cable is null modem etc .. */
3108        tty_termios_copy_hw(&tty->termios, old);
3109}
3110
3111static void gsmtty_throttle(struct tty_struct *tty)
3112{
3113        struct gsm_dlci *dlci = tty->driver_data;
3114        if (dlci->state == DLCI_CLOSED)
3115                return;
3116        if (tty->termios.c_cflag & CRTSCTS)
3117                dlci->modem_tx &= ~TIOCM_DTR;
3118        dlci->throttled = 1;
3119        /* Send an MSC with DTR cleared */
3120        gsmtty_modem_update(dlci, 0);
3121}
3122
3123static void gsmtty_unthrottle(struct tty_struct *tty)
3124{
3125        struct gsm_dlci *dlci = tty->driver_data;
3126        if (dlci->state == DLCI_CLOSED)
3127                return;
3128        if (tty->termios.c_cflag & CRTSCTS)
3129                dlci->modem_tx |= TIOCM_DTR;
3130        dlci->throttled = 0;
3131        /* Send an MSC with DTR set */
3132        gsmtty_modem_update(dlci, 0);
3133}
3134
3135static int gsmtty_break_ctl(struct tty_struct *tty, int state)
3136{
3137        struct gsm_dlci *dlci = tty->driver_data;
3138        int encode = 0; /* Off */
3139        if (dlci->state == DLCI_CLOSED)
3140                return -EINVAL;
3141
3142        if (state == -1)        /* "On indefinitely" - we can't encode this
3143                                    properly */
3144                encode = 0x0F;
3145        else if (state > 0) {
3146                encode = state / 200;   /* mS to encoding */
3147                if (encode > 0x0F)
3148                        encode = 0x0F;  /* Best effort */
3149        }
3150        return gsmtty_modem_update(dlci, encode);
3151}
3152
3153
3154/* Virtual ttys for the demux */
3155static const struct tty_operations gsmtty_ops = {
3156        .install                = gsmtty_install,
3157        .open                   = gsmtty_open,
3158        .close                  = gsmtty_close,
3159        .write                  = gsmtty_write,
3160        .write_room             = gsmtty_write_room,
3161        .chars_in_buffer        = gsmtty_chars_in_buffer,
3162        .flush_buffer           = gsmtty_flush_buffer,
3163        .ioctl                  = gsmtty_ioctl,
3164        .throttle               = gsmtty_throttle,
3165        .unthrottle             = gsmtty_unthrottle,
3166        .set_termios            = gsmtty_set_termios,
3167        .hangup                 = gsmtty_hangup,
3168        .wait_until_sent        = gsmtty_wait_until_sent,
3169        .tiocmget               = gsmtty_tiocmget,
3170        .tiocmset               = gsmtty_tiocmset,
3171        .break_ctl              = gsmtty_break_ctl,
3172};
3173
3174
3175
3176static int __init gsm_init(void)
3177{
3178        /* Fill in our line protocol discipline, and register it */
3179        int status = tty_register_ldisc(N_GSM0710, &tty_ldisc_packet);
3180        if (status != 0) {
3181                pr_err("n_gsm: can't register line discipline (err = %d)\n",
3182                                                                status);
3183                return status;
3184        }
3185
3186        gsm_tty_driver = alloc_tty_driver(256);
3187        if (!gsm_tty_driver) {
3188                tty_unregister_ldisc(N_GSM0710);
3189                pr_err("gsm_init: tty allocation failed.\n");
3190                return -EINVAL;
3191        }
3192        gsm_tty_driver->driver_name     = "gsmtty";
3193        gsm_tty_driver->name            = "gsmtty";
3194        gsm_tty_driver->major           = 0;    /* Dynamic */
3195        gsm_tty_driver->minor_start     = 0;
3196        gsm_tty_driver->type            = TTY_DRIVER_TYPE_SERIAL;
3197        gsm_tty_driver->subtype = SERIAL_TYPE_NORMAL;
3198        gsm_tty_driver->flags   = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV
3199                                                | TTY_DRIVER_HARDWARE_BREAK;
3200        gsm_tty_driver->init_termios    = tty_std_termios;
3201        /* Fixme */
3202        gsm_tty_driver->init_termios.c_lflag &= ~ECHO;
3203        tty_set_operations(gsm_tty_driver, &gsmtty_ops);
3204
3205        spin_lock_init(&gsm_mux_lock);
3206
3207        if (tty_register_driver(gsm_tty_driver)) {
3208                put_tty_driver(gsm_tty_driver);
3209                tty_unregister_ldisc(N_GSM0710);
3210                pr_err("gsm_init: tty registration failed.\n");
3211                return -EBUSY;
3212        }
3213        pr_debug("gsm_init: loaded as %d,%d.\n",
3214                        gsm_tty_driver->major, gsm_tty_driver->minor_start);
3215        return 0;
3216}
3217
3218static void __exit gsm_exit(void)
3219{
3220        int status = tty_unregister_ldisc(N_GSM0710);
3221        if (status != 0)
3222                pr_err("n_gsm: can't unregister line discipline (err = %d)\n",
3223                                                                status);
3224        tty_unregister_driver(gsm_tty_driver);
3225        put_tty_driver(gsm_tty_driver);
3226}
3227
3228module_init(gsm_init);
3229module_exit(gsm_exit);
3230
3231
3232MODULE_LICENSE("GPL");
3233MODULE_ALIAS_LDISC(N_GSM0710);
3234
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.