1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * n_gsm.c GSM 0710 tty multiplexor 4 * Copyright (c) 2009/10 Intel Corporation 5 * 6 * * THIS IS A DEVELOPMENT SNAPSHOT IT IS NOT A FINAL RELEASE * 7 * 8 * TO DO: 9 * Mostly done: ioctls for setting modes/timing 10 * Partly done: hooks so you can pull off frames to non tty devs 11 * Restart DLCI 0 when it closes ? 12 * Improve the tx engine 13 * Resolve tx side locking by adding a queue_head and routing 14 * all control traffic via it 15 * General tidy/document 16 * Review the locking/move to refcounts more (mux now moved to an 17 * alloc/free model ready) 18 * Use newest tty open/close port helpers and install hooks 19 * What to do about power functions ? 20 * Termios setting and negotiation 21 * Do we need a 'which mux are you' ioctl to correlate mux and tty sets 22 * 23 */ 24 25 #include <linux/types.h> 26 #include <linux/major.h> 27 #include <linux/errno.h> 28 #include <linux/signal.h> 29 #include <linux/fcntl.h> 30 #include <linux/sched/signal.h> 31 #include <linux/interrupt.h> 32 #include <linux/tty.h> 33 #include <linux/ctype.h> 34 #include <linux/mm.h> 35 #include <linux/string.h> 36 #include <linux/slab.h> 37 #include <linux/poll.h> 38 #include <linux/bitops.h> 39 #include <linux/file.h> 40 #include <linux/uaccess.h> 41 #include <linux/module.h> 42 #include <linux/timer.h> 43 #include <linux/tty_flip.h> 44 #include <linux/tty_driver.h> 45 #include <linux/serial.h> 46 #include <linux/kfifo.h> 47 #include <linux/skbuff.h> 48 #include <net/arp.h> 49 #include <linux/ip.h> 50 #include <linux/netdevice.h> 51 #include <linux/etherdevice.h> 52 #include <linux/gsmmux.h> 53 #include "tty.h" 54 55 static int debug; 56 module_param(debug, int, 0600); 57 58 /* Defaults: these are from the specification */ 59 60 #define T1 10 /* 100mS */ 61 #define T2 34 /* 333mS */ 62 #define N2 3 /* Retry 3 times */ 63 64 /* Use long timers for testing at low speed with debug on */ 65 #ifdef DEBUG_TIMING 66 #define T1 100 67 #define T2 200 68 #endif 69 70 /* 71 * Semi-arbitrary buffer size limits. 0710 is normally run with 32-64 byte 72 * limits so this is plenty 73 */ 74 #define MAX_MRU 1500 75 #define MAX_MTU 1500 76 #define GSM_NET_TX_TIMEOUT (HZ*10) 77 78 /* 79 * struct gsm_mux_net - network interface 80 * 81 * Created when net interface is initialized. 82 */ 83 struct gsm_mux_net { 84 struct kref ref; 85 struct gsm_dlci *dlci; 86 }; 87 88 /* 89 * Each block of data we have queued to go out is in the form of 90 * a gsm_msg which holds everything we need in a link layer independent 91 * format 92 */ 93 94 struct gsm_msg { 95 struct list_head list; 96 u8 addr; /* DLCI address + flags */ 97 u8 ctrl; /* Control byte + flags */ 98 unsigned int len; /* Length of data block (can be zero) */ 99 unsigned char *data; /* Points into buffer but not at the start */ 100 unsigned char buffer[]; 101 }; 102 103 enum gsm_dlci_state { 104 DLCI_CLOSED, 105 DLCI_OPENING, /* Sending SABM not seen UA */ 106 DLCI_OPEN, /* SABM/UA complete */ 107 DLCI_CLOSING, /* Sending DISC not seen UA/DM */ 108 }; 109 110 enum gsm_dlci_mode { 111 DLCI_MODE_ABM, /* Normal Asynchronous Balanced Mode */ 112 DLCI_MODE_ADM, /* Asynchronous Disconnected Mode */ 113 }; 114 115 /* 116 * Each active data link has a gsm_dlci structure associated which ties 117 * the link layer to an optional tty (if the tty side is open). To avoid 118 * complexity right now these are only ever freed up when the mux is 119 * shut down. 120 * 121 * At the moment we don't free DLCI objects until the mux is torn down 122 * this avoid object life time issues but might be worth review later. 123 */ 124 125 struct gsm_dlci { 126 struct gsm_mux *gsm; 127 int addr; 128 enum gsm_dlci_state state; 129 struct mutex mutex; 130 131 /* Link layer */ 132 enum gsm_dlci_mode mode; 133 spinlock_t lock; /* Protects the internal state */ 134 struct timer_list t1; /* Retransmit timer for SABM and UA */ 135 int retries; 136 /* Uplink tty if active */ 137 struct tty_port port; /* The tty bound to this DLCI if there is one */ 138 struct kfifo fifo; /* Queue fifo for the DLCI */ 139 int adaption; /* Adaption layer in use */ 140 int prev_adaption; 141 u32 modem_rx; /* Our incoming virtual modem lines */ 142 u32 modem_tx; /* Our outgoing modem lines */ 143 bool dead; /* Refuse re-open */ 144 /* Flow control */ 145 bool throttled; /* Private copy of throttle state */ 146 bool constipated; /* Throttle status for outgoing */ 147 /* Packetised I/O */ 148 struct sk_buff *skb; /* Frame being sent */ 149 struct sk_buff_head skb_list; /* Queued frames */ 150 /* Data handling callback */ 151 void (*data)(struct gsm_dlci *dlci, const u8 *data, int len); 152 void (*prev_data)(struct gsm_dlci *dlci, const u8 *data, int len); 153 struct net_device *net; /* network interface, if created */ 154 }; 155 156 /* DLCI 0, 62/63 are special or reserved see gsmtty_open */ 157 158 #define NUM_DLCI 64 159 160 /* 161 * DLCI 0 is used to pass control blocks out of band of the data 162 * flow (and with a higher link priority). One command can be outstanding 163 * at a time and we use this structure to manage them. They are created 164 * and destroyed by the user context, and updated by the receive paths 165 * and timers 166 */ 167 168 struct gsm_control { 169 u8 cmd; /* Command we are issuing */ 170 u8 *data; /* Data for the command in case we retransmit */ 171 int len; /* Length of block for retransmission */ 172 int done; /* Done flag */ 173 int error; /* Error if any */ 174 }; 175 176 enum gsm_mux_state { 177 GSM_SEARCH, 178 GSM_START, 179 GSM_ADDRESS, 180 GSM_CONTROL, 181 GSM_LEN, 182 GSM_DATA, 183 GSM_FCS, 184 GSM_OVERRUN, 185 GSM_LEN0, 186 GSM_LEN1, 187 GSM_SSOF, 188 }; 189 190 /* 191 * Each GSM mux we have is represented by this structure. If we are 192 * operating as an ldisc then we use this structure as our ldisc 193 * state. We need to sort out lifetimes and locking with respect 194 * to the gsm mux array. For now we don't free DLCI objects that 195 * have been instantiated until the mux itself is terminated. 196 * 197 * To consider further: tty open versus mux shutdown. 198 */ 199 200 struct gsm_mux { 201 struct tty_struct *tty; /* The tty our ldisc is bound to */ 202 spinlock_t lock; 203 struct mutex mutex; 204 unsigned int num; 205 struct kref ref; 206 207 /* Events on the GSM channel */ 208 wait_queue_head_t event; 209 210 /* Bits for GSM mode decoding */ 211 212 /* Framing Layer */ 213 unsigned char *buf; 214 enum gsm_mux_state state; 215 unsigned int len; 216 unsigned int address; 217 unsigned int count; 218 bool escape; 219 int encoding; 220 u8 control; 221 u8 fcs; 222 u8 received_fcs; 223 u8 *txframe; /* TX framing buffer */ 224 225 /* Method for the receiver side */ 226 void (*receive)(struct gsm_mux *gsm, u8 ch); 227 228 /* Link Layer */ 229 unsigned int mru; 230 unsigned int mtu; 231 int initiator; /* Did we initiate connection */ 232 bool dead; /* Has the mux been shut down */ 233 struct gsm_dlci *dlci[NUM_DLCI]; 234 bool constipated; /* Asked by remote to shut up */ 235 236 spinlock_t tx_lock; 237 unsigned int tx_bytes; /* TX data outstanding */ 238 #define TX_THRESH_HI 8192 239 #define TX_THRESH_LO 2048 240 struct list_head tx_list; /* Pending data packets */ 241 242 /* Control messages */ 243 struct timer_list t2_timer; /* Retransmit timer for commands */ 244 int cretries; /* Command retry counter */ 245 struct gsm_control *pending_cmd;/* Our current pending command */ 246 spinlock_t control_lock; /* Protects the pending command */ 247 248 /* Configuration */ 249 int adaption; /* 1 or 2 supported */ 250 u8 ftype; /* UI or UIH */ 251 int t1, t2; /* Timers in 1/100th of a sec */ 252 int n2; /* Retry count */ 253 254 /* Statistics (not currently exposed) */ 255 unsigned long bad_fcs; 256 unsigned long malformed; 257 unsigned long io_error; 258 unsigned long bad_size; 259 unsigned long unsupported; 260 }; 261 262 263 /* 264 * Mux objects - needed so that we can translate a tty index into the 265 * relevant mux and DLCI. 266 */ 267 268 #define MAX_MUX 4 /* 256 minors */ 269 static struct gsm_mux *gsm_mux[MAX_MUX]; /* GSM muxes */ 270 static DEFINE_SPINLOCK(gsm_mux_lock); 271 272 static struct tty_driver *gsm_tty_driver; 273 274 /* Save dlci open address */ 275 static int addr_open[256] = { 0 }; 276 /* Save dlci open count */ 277 static int addr_cnt; 278 /* 279 * This section of the driver logic implements the GSM encodings 280 * both the basic and the 'advanced'. Reliable transport is not 281 * supported. 282 */ 283 284 #define CR 0x02 285 #define EA 0x01 286 #define PF 0x10 287 288 /* I is special: the rest are ..*/ 289 #define RR 0x01 290 #define UI 0x03 291 #define RNR 0x05 292 #define REJ 0x09 293 #define DM 0x0F 294 #define SABM 0x2F 295 #define DISC 0x43 296 #define UA 0x63 297 #define UIH 0xEF 298 299 /* Channel commands */ 300 #define CMD_NSC 0x09 301 #define CMD_TEST 0x11 302 #define CMD_PSC 0x21 303 #define CMD_RLS 0x29 304 #define CMD_FCOFF 0x31 305 #define CMD_PN 0x41 306 #define CMD_RPN 0x49 307 #define CMD_FCON 0x51 308 #define CMD_CLD 0x61 309 #define CMD_SNC 0x69 310 #define CMD_MSC 0x71 311 312 /* Virtual modem bits */ 313 #define MDM_FC 0x01 314 #define MDM_RTC 0x02 315 #define MDM_RTR 0x04 316 #define MDM_IC 0x20 317 #define MDM_DV 0x40 318 319 #define GSM0_SOF 0xF9 320 #define GSM1_SOF 0x7E 321 #define GSM1_ESCAPE 0x7D 322 #define GSM1_ESCAPE_BITS 0x20 323 #define XON 0x11 324 #define XOFF 0x13 325 #define ISO_IEC_646_MASK 0x7F 326 327 static const struct tty_port_operations gsm_port_ops; 328 329 /* 330 * CRC table for GSM 0710 331 */ 332 333 static const u8 gsm_fcs8[256] = { 334 0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75, 335 0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B, 336 0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69, 337 0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67, 338 0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D, 339 0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43, 340 0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51, 341 0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F, 342 0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05, 343 0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B, 344 0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19, 345 0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17, 346 0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D, 347 0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33, 348 0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21, 349 0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F, 350 0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95, 351 0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B, 352 0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89, 353 0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87, 354 0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD, 355 0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3, 356 0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1, 357 0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF, 358 0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5, 359 0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB, 360 0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9, 361 0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7, 362 0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD, 363 0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3, 364 0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1, 365 0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF 366 }; 367 368 #define INIT_FCS 0xFF 369 #define GOOD_FCS 0xCF 370 371 static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len); 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 */ 381 382 static 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 */ 396 397 static 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 */ 412 413 static 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 */ 429 430 static 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 || dlci->gsm->initiator) 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 seen as initiator 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 */ 459 460 static 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 print_hex_dump_bytes("", DUMP_PREFIX_NONE, data, dlen); 512 } 513 514 515 /* 516 * Link level transmission side 517 */ 518 519 /** 520 * gsm_stuff_frame - bytestuff a packet 521 * @input: input buffer 522 * @output: output buffer 523 * @len: length of input 524 * 525 * Expand a buffer by bytestuffing it. The worst case size change 526 * is doubling and the caller is responsible for handing out 527 * suitable sized buffers. 528 */ 529 530 static int gsm_stuff_frame(const u8 *input, u8 *output, int len) 531 { 532 int olen = 0; 533 while (len--) { 534 if (*input == GSM1_SOF || *input == GSM1_ESCAPE 535 || (*input & ISO_IEC_646_MASK) == XON 536 || (*input & ISO_IEC_646_MASK) == XOFF) { 537 *output++ = GSM1_ESCAPE; 538 *output++ = *input++ ^ GSM1_ESCAPE_BITS; 539 olen++; 540 } else 541 *output++ = *input++; 542 olen++; 543 } 544 return olen; 545 } 546 547 /** 548 * gsm_send - send a control frame 549 * @gsm: our GSM mux 550 * @addr: address for control frame 551 * @cr: command/response bit seen as initiator 552 * @control: control byte including PF bit 553 * 554 * Format up and transmit a control frame. These do not go via the 555 * queueing logic as they should be transmitted ahead of data when 556 * they are needed. 557 * 558 * FIXME: Lock versus data TX path 559 */ 560 561 static void gsm_send(struct gsm_mux *gsm, int addr, int cr, int control) 562 { 563 int len; 564 u8 cbuf[10]; 565 u8 ibuf[3]; 566 int ocr; 567 568 /* toggle C/R coding if not initiator */ 569 ocr = cr ^ (gsm->initiator ? 0 : 1); 570 571 switch (gsm->encoding) { 572 case 0: 573 cbuf[0] = GSM0_SOF; 574 cbuf[1] = (addr << 2) | (ocr << 1) | EA; 575 cbuf[2] = control; 576 cbuf[3] = EA; /* Length of data = 0 */ 577 cbuf[4] = 0xFF - gsm_fcs_add_block(INIT_FCS, cbuf + 1, 3); 578 cbuf[5] = GSM0_SOF; 579 len = 6; 580 break; 581 case 1: 582 case 2: 583 /* Control frame + packing (but not frame stuffing) in mode 1 */ 584 ibuf[0] = (addr << 2) | (ocr << 1) | EA; 585 ibuf[1] = control; 586 ibuf[2] = 0xFF - gsm_fcs_add_block(INIT_FCS, ibuf, 2); 587 /* Stuffing may double the size worst case */ 588 len = gsm_stuff_frame(ibuf, cbuf + 1, 3); 589 /* Now add the SOF markers */ 590 cbuf[0] = GSM1_SOF; 591 cbuf[len + 1] = GSM1_SOF; 592 /* FIXME: we can omit the lead one in many cases */ 593 len += 2; 594 break; 595 default: 596 WARN_ON(1); 597 return; 598 } 599 gsmld_output(gsm, cbuf, len); 600 if (!gsm->initiator) { 601 cr = cr & gsm->initiator; 602 control = control & ~PF; 603 } 604 gsm_print_packet("-->", addr, cr, control, NULL, 0); 605 } 606 607 /** 608 * gsm_response - send a control response 609 * @gsm: our GSM mux 610 * @addr: address for control frame 611 * @control: control byte including PF bit 612 * 613 * Format up and transmit a link level response frame. 614 */ 615 616 static inline void gsm_response(struct gsm_mux *gsm, int addr, int control) 617 { 618 gsm_send(gsm, addr, 0, control); 619 } 620 621 /** 622 * gsm_command - send a control command 623 * @gsm: our GSM mux 624 * @addr: address for control frame 625 * @control: control byte including PF bit 626 * 627 * Format up and transmit a link level command frame. 628 */ 629 630 static inline void gsm_command(struct gsm_mux *gsm, int addr, int control) 631 { 632 gsm_send(gsm, addr, 1, control); 633 } 634 635 /* Data transmission */ 636 637 #define HDR_LEN 6 /* ADDR CTRL [LEN.2] DATA FCS */ 638 639 /** 640 * gsm_data_alloc - allocate data frame 641 * @gsm: GSM mux 642 * @addr: DLCI address 643 * @len: length excluding header and FCS 644 * @ctrl: control byte 645 * 646 * Allocate a new data buffer for sending frames with data. Space is left 647 * at the front for header bytes but that is treated as an implementation 648 * detail and not for the high level code to use 649 */ 650 651 static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len, 652 u8 ctrl) 653 { 654 struct gsm_msg *m = kmalloc(sizeof(struct gsm_msg) + len + HDR_LEN, 655 GFP_ATOMIC); 656 if (m == NULL) 657 return NULL; 658 m->data = m->buffer + HDR_LEN - 1; /* Allow for FCS */ 659 m->len = len; 660 m->addr = addr; 661 m->ctrl = ctrl; 662 INIT_LIST_HEAD(&m->list); 663 return m; 664 } 665 666 /** 667 * gsm_data_kick - poke the queue 668 * @gsm: GSM Mux 669 * @dlci: DLCI sending the data 670 * 671 * The tty device has called us to indicate that room has appeared in 672 * the transmit queue. Ram more data into the pipe if we have any 673 * If we have been flow-stopped by a CMD_FCOFF, then we can only 674 * send messages on DLCI0 until CMD_FCON 675 * 676 * FIXME: lock against link layer control transmissions 677 */ 678 679 static void gsm_data_kick(struct gsm_mux *gsm, struct gsm_dlci *dlci) 680 { 681 struct gsm_msg *msg, *nmsg; 682 int len; 683 684 list_for_each_entry_safe(msg, nmsg, &gsm->tx_list, list) { 685 if (gsm->constipated && msg->addr) 686 continue; 687 if (gsm->encoding != 0) { 688 gsm->txframe[0] = GSM1_SOF; 689 len = gsm_stuff_frame(msg->data, 690 gsm->txframe + 1, msg->len); 691 gsm->txframe[len + 1] = GSM1_SOF; 692 len += 2; 693 } else { 694 gsm->txframe[0] = GSM0_SOF; 695 memcpy(gsm->txframe + 1 , msg->data, msg->len); 696 gsm->txframe[msg->len + 1] = GSM0_SOF; 697 len = msg->len + 2; 698 } 699 700 if (debug & 4) 701 print_hex_dump_bytes("gsm_data_kick: ", 702 DUMP_PREFIX_OFFSET, 703 gsm->txframe, len); 704 if (gsmld_output(gsm, gsm->txframe, len) <= 0) 705 break; 706 /* FIXME: Can eliminate one SOF in many more cases */ 707 gsm->tx_bytes -= msg->len; 708 709 list_del(&msg->list); 710 kfree(msg); 711 712 if (dlci) { 713 tty_port_tty_wakeup(&dlci->port); 714 } else { 715 int i = 0; 716 717 for (i = 0; i < NUM_DLCI; i++) 718 if (gsm->dlci[i]) 719 tty_port_tty_wakeup(&gsm->dlci[i]->port); 720 } 721 } 722 } 723 724 /** 725 * __gsm_data_queue - queue a UI or UIH frame 726 * @dlci: DLCI sending the data 727 * @msg: message queued 728 * 729 * Add data to the transmit queue and try and get stuff moving 730 * out of the mux tty if not already doing so. The Caller must hold 731 * the gsm tx lock. 732 */ 733 734 static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg) 735 { 736 struct gsm_mux *gsm = dlci->gsm; 737 u8 *dp = msg->data; 738 u8 *fcs = dp + msg->len; 739 740 /* Fill in the header */ 741 if (gsm->encoding == 0) { 742 if (msg->len < 128) 743 *--dp = (msg->len << 1) | EA; 744 else { 745 *--dp = (msg->len >> 7); /* bits 7 - 15 */ 746 *--dp = (msg->len & 127) << 1; /* bits 0 - 6 */ 747 } 748 } 749 750 *--dp = msg->ctrl; 751 if (gsm->initiator) 752 *--dp = (msg->addr << 2) | 2 | EA; 753 else 754 *--dp = (msg->addr << 2) | EA; 755 *fcs = gsm_fcs_add_block(INIT_FCS, dp , msg->data - dp); 756 /* Ugly protocol layering violation */ 757 if (msg->ctrl == UI || msg->ctrl == (UI|PF)) 758 *fcs = gsm_fcs_add_block(*fcs, msg->data, msg->len); 759 *fcs = 0xFF - *fcs; 760 761 gsm_print_packet("Q> ", msg->addr, gsm->initiator, msg->ctrl, 762 msg->data, msg->len); 763 764 /* Move the header back and adjust the length, also allow for the FCS 765 now tacked on the end */ 766 msg->len += (msg->data - dp) + 1; 767 msg->data = dp; 768 769 /* Add to the actual output queue */ 770 list_add_tail(&msg->list, &gsm->tx_list); 771 gsm->tx_bytes += msg->len; 772 gsm_data_kick(gsm, dlci); 773 } 774 775 /** 776 * gsm_data_queue - queue a UI or UIH frame 777 * @dlci: DLCI sending the data 778 * @msg: message queued 779 * 780 * Add data to the transmit queue and try and get stuff moving 781 * out of the mux tty if not already doing so. Take the 782 * the gsm tx lock and dlci lock. 783 */ 784 785 static void gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg) 786 { 787 unsigned long flags; 788 spin_lock_irqsave(&dlci->gsm->tx_lock, flags); 789 __gsm_data_queue(dlci, msg); 790 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags); 791 } 792 793 /** 794 * gsm_dlci_data_output - try and push data out of a DLCI 795 * @gsm: mux 796 * @dlci: the DLCI to pull data from 797 * 798 * Pull data from a DLCI and send it into the transmit queue if there 799 * is data. Keep to the MRU of the mux. This path handles the usual tty 800 * interface which is a byte stream with optional modem data. 801 * 802 * Caller must hold the tx_lock of the mux. 803 */ 804 805 static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci) 806 { 807 struct gsm_msg *msg; 808 u8 *dp; 809 int len, total_size, size; 810 int h = dlci->adaption - 1; 811 812 total_size = 0; 813 while (1) { 814 len = kfifo_len(&dlci->fifo); 815 if (len == 0) 816 return total_size; 817 818 /* MTU/MRU count only the data bits */ 819 if (len > gsm->mtu) 820 len = gsm->mtu; 821 822 size = len + h; 823 824 msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype); 825 /* FIXME: need a timer or something to kick this so it can't 826 get stuck with no work outstanding and no buffer free */ 827 if (msg == NULL) 828 return -ENOMEM; 829 dp = msg->data; 830 switch (dlci->adaption) { 831 case 1: /* Unstructured */ 832 break; 833 case 2: /* Unstructed with modem bits. 834 Always one byte as we never send inline break data */ 835 *dp++ = gsm_encode_modem(dlci); 836 break; 837 } 838 WARN_ON(kfifo_out_locked(&dlci->fifo, dp , len, &dlci->lock) != len); 839 __gsm_data_queue(dlci, msg); 840 total_size += size; 841 } 842 /* Bytes of data we used up */ 843 return total_size; 844 } 845 846 /** 847 * gsm_dlci_data_output_framed - try and push data out of a DLCI 848 * @gsm: mux 849 * @dlci: the DLCI to pull data from 850 * 851 * Pull data from a DLCI and send it into the transmit queue if there 852 * is data. Keep to the MRU of the mux. This path handles framed data 853 * queued as skbuffs to the DLCI. 854 * 855 * Caller must hold the tx_lock of the mux. 856 */ 857 858 static int gsm_dlci_data_output_framed(struct gsm_mux *gsm, 859 struct gsm_dlci *dlci) 860 { 861 struct gsm_msg *msg; 862 u8 *dp; 863 int len, size; 864 int last = 0, first = 0; 865 int overhead = 0; 866 867 /* One byte per frame is used for B/F flags */ 868 if (dlci->adaption == 4) 869 overhead = 1; 870 871 /* dlci->skb is locked by tx_lock */ 872 if (dlci->skb == NULL) { 873 dlci->skb = skb_dequeue_tail(&dlci->skb_list); 874 if (dlci->skb == NULL) 875 return 0; 876 first = 1; 877 } 878 len = dlci->skb->len + overhead; 879 880 /* MTU/MRU count only the data bits */ 881 if (len > gsm->mtu) { 882 if (dlci->adaption == 3) { 883 /* Over long frame, bin it */ 884 dev_kfree_skb_any(dlci->skb); 885 dlci->skb = NULL; 886 return 0; 887 } 888 len = gsm->mtu; 889 } else 890 last = 1; 891 892 size = len + overhead; 893 msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype); 894 895 /* FIXME: need a timer or something to kick this so it can't 896 get stuck with no work outstanding and no buffer free */ 897 if (msg == NULL) { 898 skb_queue_tail(&dlci->skb_list, dlci->skb); 899 dlci->skb = NULL; 900 return -ENOMEM; 901 } 902 dp = msg->data; 903 904 if (dlci->adaption == 4) { /* Interruptible framed (Packetised Data) */ 905 /* Flag byte to carry the start/end info */ 906 *dp++ = last << 7 | first << 6 | 1; /* EA */ 907 len--; 908 } 909 memcpy(dp, dlci->skb->data, len); 910 skb_pull(dlci->skb, len); 911 __gsm_data_queue(dlci, msg); 912 if (last) { 913 dev_kfree_skb_any(dlci->skb); 914 dlci->skb = NULL; 915 } 916 return size; 917 } 918 919 /** 920 * gsm_dlci_data_sweep - look for data to send 921 * @gsm: the GSM mux 922 * 923 * Sweep the GSM mux channels in priority order looking for ones with 924 * data to send. We could do with optimising this scan a bit. We aim 925 * to fill the queue totally or up to TX_THRESH_HI bytes. Once we hit 926 * TX_THRESH_LO we get called again 927 * 928 * FIXME: We should round robin between groups and in theory you can 929 * renegotiate DLCI priorities with optional stuff. Needs optimising. 930 */ 931 932 static void gsm_dlci_data_sweep(struct gsm_mux *gsm) 933 { 934 int len; 935 /* Priority ordering: We should do priority with RR of the groups */ 936 int i = 1; 937 938 while (i < NUM_DLCI) { 939 struct gsm_dlci *dlci; 940 941 if (gsm->tx_bytes > TX_THRESH_HI) 942 break; 943 dlci = gsm->dlci[i]; 944 if (dlci == NULL || dlci->constipated) { 945 i++; 946 continue; 947 } 948 if (dlci->adaption < 3 && !dlci->net) 949 len = gsm_dlci_data_output(gsm, dlci); 950 else 951 len = gsm_dlci_data_output_framed(gsm, dlci); 952 if (len < 0) 953 break; 954 /* DLCI empty - try the next */ 955 if (len == 0) 956 i++; 957 } 958 } 959 960 /** 961 * gsm_dlci_data_kick - transmit if possible 962 * @dlci: DLCI to kick 963 * 964 * Transmit data from this DLCI if the queue is empty. We can't rely on 965 * a tty wakeup except when we filled the pipe so we need to fire off 966 * new data ourselves in other cases. 967 */ 968 969 static void gsm_dlci_data_kick(struct gsm_dlci *dlci) 970 { 971 unsigned long flags; 972 int sweep; 973 974 if (dlci->constipated) 975 return; 976 977 spin_lock_irqsave(&dlci->gsm->tx_lock, flags); 978 /* If we have nothing running then we need to fire up */ 979 sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO); 980 if (dlci->gsm->tx_bytes == 0) { 981 if (dlci->net) 982 gsm_dlci_data_output_framed(dlci->gsm, dlci); 983 else 984 gsm_dlci_data_output(dlci->gsm, dlci); 985 } 986 if (sweep) 987 gsm_dlci_data_sweep(dlci->gsm); 988 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags); 989 } 990 991 /* 992 * Control message processing 993 */ 994 995 996 /** 997 * gsm_control_reply - send a response frame to a control 998 * @gsm: gsm channel 999 * @cmd: the command to use 1000 * @data: data to follow encoded info 1001 * @dlen: length of data 1002 * 1003 * Encode up and queue a UI/UIH frame containing our response. 1004 */ 1005 1006 static void gsm_control_reply(struct gsm_mux *gsm, int cmd, const u8 *data, 1007 int dlen) 1008 { 1009 struct gsm_msg *msg; 1010 msg = gsm_data_alloc(gsm, 0, dlen + 2, gsm->ftype); 1011 if (msg == NULL) 1012 return; 1013 msg->data[0] = (cmd & 0xFE) << 1 | EA; /* Clear C/R */ 1014 msg->data[1] = (dlen << 1) | EA; 1015 memcpy(msg->data + 2, data, dlen); 1016 gsm_data_queue(gsm->dlci[0], msg); 1017 } 1018 1019 /** 1020 * gsm_process_modem - process received modem status 1021 * @tty: virtual tty bound to the DLCI 1022 * @dlci: DLCI to affect 1023 * @modem: modem bits (full EA) 1024 * @slen: number of signal octets 1025 * 1026 * Used when a modem control message or line state inline in adaption 1027 * layer 2 is processed. Sort out the local modem state and throttles 1028 */ 1029 1030 static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci, 1031 u32 modem, int slen) 1032 { 1033 int mlines = 0; 1034 u8 brk = 0; 1035 int fc; 1036 1037 /* The modem status command can either contain one octet (V.24 signals) 1038 * or two octets (V.24 signals + break signals). This is specified in 1039 * section 5.4.6.3.7 of the 07.10 mux spec. 1040 */ 1041 1042 if (slen == 1) 1043 modem = modem & 0x7f; 1044 else { 1045 brk = modem & 0x7f; 1046 modem = (modem >> 7) & 0x7f; 1047 } 1048 1049 /* Flow control/ready to communicate */ 1050 fc = (modem & MDM_FC) || !(modem & MDM_RTR); 1051 if (fc && !dlci->constipated) { 1052 /* Need to throttle our output on this device */ 1053 dlci->constipated = true; 1054 } else if (!fc && dlci->constipated) { 1055 dlci->constipated = false; 1056 gsm_dlci_data_kick(dlci); 1057 } 1058 1059 /* Map modem bits */ 1060 if (modem & MDM_RTC) 1061 mlines |= TIOCM_DSR | TIOCM_DTR; 1062 if (modem & MDM_RTR) 1063 mlines |= TIOCM_RTS | TIOCM_CTS; 1064 if (modem & MDM_IC) 1065 mlines |= TIOCM_RI; 1066 if (modem & MDM_DV) 1067 mlines |= TIOCM_CD; 1068 1069 /* Carrier drop -> hangup */ 1070 if (tty) { 1071 if ((mlines & TIOCM_CD) == 0 && (dlci->modem_rx & TIOCM_CD)) 1072 if (!C_CLOCAL(tty)) 1073 tty_hangup(tty); 1074 } 1075 if (brk & 0x01) 1076 tty_insert_flip_char(&dlci->port, 0, TTY_BREAK); 1077 dlci->modem_rx = mlines; 1078 } 1079 1080 /** 1081 * gsm_control_modem - modem status received 1082 * @gsm: GSM channel 1083 * @data: data following command 1084 * @clen: command length 1085 * 1086 * We have received a modem status control message. This is used by 1087 * the GSM mux protocol to pass virtual modem line status and optionally 1088 * to indicate break signals. Unpack it, convert to Linux representation 1089 * and if need be stuff a break message down the tty. 1090 */ 1091 1092 static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen) 1093 { 1094 unsigned int addr = 0; 1095 unsigned int modem = 0; 1096 unsigned int brk = 0; 1097 struct gsm_dlci *dlci; 1098 int len = clen; 1099 int slen; 1100 const u8 *dp = data; 1101 struct tty_struct *tty; 1102 1103 while (gsm_read_ea(&addr, *dp++) == 0) { 1104 len--; 1105 if (len == 0) 1106 return; 1107 } 1108 /* Must be at least one byte following the EA */ 1109 len--; 1110 if (len <= 0) 1111 return; 1112 1113 addr >>= 1; 1114 /* Closed port, or invalid ? */ 1115 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL) 1116 return; 1117 dlci = gsm->dlci[addr]; 1118 1119 slen = len; 1120 while (gsm_read_ea(&modem, *dp++) == 0) { 1121 len--; 1122 if (len == 0) 1123 return; 1124 } 1125 len--; 1126 if (len > 0) { 1127 while (gsm_read_ea(&brk, *dp++) == 0) { 1128 len--; 1129 if (len == 0) 1130 return; 1131 } 1132 modem <<= 7; 1133 modem |= (brk & 0x7f); 1134 } 1135 tty = tty_port_tty_get(&dlci->port); 1136 gsm_process_modem(tty, dlci, modem, slen); 1137 if (tty) { 1138 tty_wakeup(tty); 1139 tty_kref_put(tty); 1140 } 1141 gsm_control_reply(gsm, CMD_MSC, data, clen); 1142 } 1143 1144 /** 1145 * gsm_control_rls - remote line status 1146 * @gsm: GSM channel 1147 * @data: data bytes 1148 * @clen: data length 1149 * 1150 * The modem sends us a two byte message on the control channel whenever 1151 * it wishes to send us an error state from the virtual link. Stuff 1152 * this into the uplink tty if present 1153 */ 1154 1155 static void gsm_control_rls(struct gsm_mux *gsm, const u8 *data, int clen) 1156 { 1157 struct tty_port *port; 1158 unsigned int addr = 0; 1159 u8 bits; 1160 int len = clen; 1161 const u8 *dp = data; 1162 1163 while (gsm_read_ea(&addr, *dp++) == 0) { 1164 len--; 1165 if (len == 0) 1166 return; 1167 } 1168 /* Must be at least one byte following ea */ 1169 len--; 1170 if (len <= 0) 1171 return; 1172 addr >>= 1; 1173 /* Closed port, or invalid ? */ 1174 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL) 1175 return; 1176 /* No error ? */ 1177 bits = *dp; 1178 if ((bits & 1) == 0) 1179 return; 1180 1181 port = &gsm->dlci[addr]->port; 1182 1183 if (bits & 2) 1184 tty_insert_flip_char(port, 0, TTY_OVERRUN); 1185 if (bits & 4) 1186 tty_insert_flip_char(port, 0, TTY_PARITY); 1187 if (bits & 8) 1188 tty_insert_flip_char(port, 0, TTY_FRAME); 1189 1190 tty_flip_buffer_push(port); 1191 1192 gsm_control_reply(gsm, CMD_RLS, data, clen); 1193 } 1194 1195 static void gsm_dlci_begin_close(struct gsm_dlci *dlci); 1196 static void gsm_dlci_close(struct gsm_dlci *dlci); 1197 1198 /** 1199 * gsm_control_message - DLCI 0 control processing 1200 * @gsm: our GSM mux 1201 * @command: the command EA 1202 * @data: data beyond the command/length EAs 1203 * @clen: length 1204 * 1205 * Input processor for control messages from the other end of the link. 1206 * Processes the incoming request and queues a response frame or an 1207 * NSC response if not supported 1208 */ 1209 1210 static void gsm_control_message(struct gsm_mux *gsm, unsigned int command, 1211 const u8 *data, int clen) 1212 { 1213 u8 buf[1]; 1214 unsigned long flags; 1215 struct gsm_dlci *dlci; 1216 int i; 1217 int address; 1218 1219 switch (command) { 1220 case CMD_CLD: { 1221 if (addr_cnt > 0) { 1222 for (i = 0; i < addr_cnt; i++) { 1223 address = addr_open[i]; 1224 dlci = gsm->dlci[address]; 1225 gsm_dlci_close(dlci); 1226 addr_open[i] = 0; 1227 } 1228 } 1229 /* Modem wishes to close down */ 1230 dlci = gsm->dlci[0]; 1231 if (dlci) { 1232 dlci->dead = true; 1233 gsm->dead = true; 1234 gsm_dlci_close(dlci); 1235 addr_cnt = 0; 1236 gsm_response(gsm, 0, UA|PF); 1237 } 1238 } 1239 break; 1240 case CMD_TEST: 1241 /* Modem wishes to test, reply with the data */ 1242 gsm_control_reply(gsm, CMD_TEST, data, clen); 1243 break; 1244 case CMD_FCON: 1245 /* Modem can accept data again */ 1246 gsm->constipated = false; 1247 gsm_control_reply(gsm, CMD_FCON, NULL, 0); 1248 /* Kick the link in case it is idling */ 1249 spin_lock_irqsave(&gsm->tx_lock, flags); 1250 gsm_data_kick(gsm, NULL); 1251 spin_unlock_irqrestore(&gsm->tx_lock, flags); 1252 break; 1253 case CMD_FCOFF: 1254 /* Modem wants us to STFU */ 1255 gsm->constipated = true; 1256 gsm_control_reply(gsm, CMD_FCOFF, NULL, 0); 1257 break; 1258 case CMD_MSC: 1259 /* Out of band modem line change indicator for a DLCI */ 1260 gsm_control_modem(gsm, data, clen); 1261 break; 1262 case CMD_RLS: 1263 /* Out of band error reception for a DLCI */ 1264 gsm_control_rls(gsm, data, clen); 1265 break; 1266 case CMD_PSC: 1267 /* Modem wishes to enter power saving state */ 1268 gsm_control_reply(gsm, CMD_PSC, NULL, 0); 1269 break; 1270 /* Optional unsupported commands */ 1271 case CMD_PN: /* Parameter negotiation */ 1272 case CMD_RPN: /* Remote port negotiation */ 1273 case CMD_SNC: /* Service negotiation command */ 1274 default: 1275 /* Reply to bad commands with an NSC */ 1276 buf[0] = command; 1277 gsm_control_reply(gsm, CMD_NSC, buf, 1); 1278 break; 1279 } 1280 } 1281 1282 /** 1283 * gsm_control_response - process a response to our control 1284 * @gsm: our GSM mux 1285 * @command: the command (response) EA 1286 * @data: data beyond the command/length EA 1287 * @clen: length 1288 * 1289 * Process a response to an outstanding command. We only allow a single 1290 * control message in flight so this is fairly easy. All the clean up 1291 * is done by the caller, we just update the fields, flag it as done 1292 * and return 1293 */ 1294 1295 static void gsm_control_response(struct gsm_mux *gsm, unsigned int command, 1296 const u8 *data, int clen) 1297 { 1298 struct gsm_control *ctrl; 1299 unsigned long flags; 1300 1301 spin_lock_irqsave(&gsm->control_lock, flags); 1302 1303 ctrl = gsm->pending_cmd; 1304 /* Does the reply match our command */ 1305 command |= 1; 1306 if (ctrl != NULL && (command == ctrl->cmd || command == CMD_NSC)) { 1307 /* Our command was replied to, kill the retry timer */ 1308 del_timer(&gsm->t2_timer); 1309 gsm->pending_cmd = NULL; 1310 /* Rejected by the other end */ 1311 if (command == CMD_NSC) 1312 ctrl->error = -EOPNOTSUPP; 1313 ctrl->done = 1; 1314 wake_up(&gsm->event); 1315 } 1316 spin_unlock_irqrestore(&gsm->control_lock, flags); 1317 } 1318 1319 /** 1320 * gsm_control_transmit - send control packet 1321 * @gsm: gsm mux 1322 * @ctrl: frame to send 1323 * 1324 * Send out a pending control command (called under control lock) 1325 */ 1326 1327 static void gsm_control_transmit(struct gsm_mux *gsm, struct gsm_control *ctrl) 1328 { 1329 struct gsm_msg *msg = gsm_data_alloc(gsm, 0, ctrl->len + 1, gsm->ftype); 1330 if (msg == NULL) 1331 return; 1332 msg->data[0] = (ctrl->cmd << 1) | 2 | EA; /* command */ 1333 memcpy(msg->data + 1, ctrl->data, ctrl->len); 1334 gsm_data_queue(gsm->dlci[0], msg); 1335 } 1336 1337 /** 1338 * gsm_control_retransmit - retransmit a control frame 1339 * @t: timer contained in our gsm object 1340 * 1341 * Called off the T2 timer expiry in order to retransmit control frames 1342 * that have been lost in the system somewhere. The control_lock protects 1343 * us from colliding with another sender or a receive completion event. 1344 * In that situation the timer may still occur in a small window but 1345 * gsm->pending_cmd will be NULL and we just let the timer expire. 1346 */ 1347 1348 static void gsm_control_retransmit(struct timer_list *t) 1349 { 1350 struct gsm_mux *gsm = from_timer(gsm, t, t2_timer); 1351 struct gsm_control *ctrl; 1352 unsigned long flags; 1353 spin_lock_irqsave(&gsm->control_lock, flags); 1354 ctrl = gsm->pending_cmd; 1355 if (ctrl) { 1356 gsm->cretries--; 1357 if (gsm->cretries == 0) { 1358 gsm->pending_cmd = NULL; 1359 ctrl->error = -ETIMEDOUT; 1360 ctrl->done = 1; 1361 spin_unlock_irqrestore(&gsm->control_lock, flags); 1362 wake_up(&gsm->event); 1363 return; 1364 } 1365 gsm_control_transmit(gsm, ctrl); 1366 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100); 1367 } 1368 spin_unlock_irqrestore(&gsm->control_lock, flags); 1369 } 1370 1371 /** 1372 * gsm_control_send - send a control frame on DLCI 0 1373 * @gsm: the GSM channel 1374 * @command: command to send including CR bit 1375 * @data: bytes of data (must be kmalloced) 1376 * @clen: length of the block to send 1377 * 1378 * Queue and dispatch a control command. Only one command can be 1379 * active at a time. In theory more can be outstanding but the matching 1380 * gets really complicated so for now stick to one outstanding. 1381 */ 1382 1383 static struct gsm_control *gsm_control_send(struct gsm_mux *gsm, 1384 unsigned int command, u8 *data, int clen) 1385 { 1386 struct gsm_control *ctrl = kzalloc(sizeof(struct gsm_control), 1387 GFP_KERNEL); 1388 unsigned long flags; 1389 if (ctrl == NULL) 1390 return NULL; 1391 retry: 1392 wait_event(gsm->event, gsm->pending_cmd == NULL); 1393 spin_lock_irqsave(&gsm->control_lock, flags); 1394 if (gsm->pending_cmd != NULL) { 1395 spin_unlock_irqrestore(&gsm->control_lock, flags); 1396 goto retry; 1397 } 1398 ctrl->cmd = command; 1399 ctrl->data = data; 1400 ctrl->len = clen; 1401 gsm->pending_cmd = ctrl; 1402 1403 /* If DLCI0 is in ADM mode skip retries, it won't respond */ 1404 if (gsm->dlci[0]->mode == DLCI_MODE_ADM) 1405 gsm->cretries = 1; 1406 else 1407 gsm->cretries = gsm->n2; 1408 1409 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100); 1410 gsm_control_transmit(gsm, ctrl); 1411 spin_unlock_irqrestore(&gsm->control_lock, flags); 1412 return ctrl; 1413 } 1414 1415 /** 1416 * gsm_control_wait - wait for a control to finish 1417 * @gsm: GSM mux 1418 * @control: control we are waiting on 1419 * 1420 * Waits for the control to complete or time out. Frees any used 1421 * resources and returns 0 for success, or an error if the remote 1422 * rejected or ignored the request. 1423 */ 1424 1425 static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control) 1426 { 1427 int err; 1428 wait_event(gsm->event, control->done == 1); 1429 err = control->error; 1430 kfree(control); 1431 return err; 1432 } 1433 1434 1435 /* 1436 * DLCI level handling: Needs krefs 1437 */ 1438 1439 /* 1440 * State transitions and timers 1441 */ 1442 1443 /** 1444 * gsm_dlci_close - a DLCI has closed 1445 * @dlci: DLCI that closed 1446 * 1447 * Perform processing when moving a DLCI into closed state. If there 1448 * is an attached tty this is hung up 1449 */ 1450 1451 static void gsm_dlci_close(struct gsm_dlci *dlci) 1452 { 1453 del_timer(&dlci->t1); 1454 if (debug & 8) 1455 pr_debug("DLCI %d goes closed.\n", dlci->addr); 1456 dlci->state = DLCI_CLOSED; 1457 if (dlci->addr != 0) { 1458 tty_port_tty_hangup(&dlci->port, false); 1459 kfifo_reset(&dlci->fifo); 1460 /* Ensure that gsmtty_open() can return. */ 1461 tty_port_set_initialized(&dlci->port, 0); 1462 wake_up_interruptible(&dlci->port.open_wait); 1463 } else 1464 dlci->gsm->dead = true; 1465 /* Unregister gsmtty driver,report gsmtty dev remove uevent for user */ 1466 tty_unregister_device(gsm_tty_driver, dlci->addr); 1467 wake_up(&dlci->gsm->event); 1468 /* A DLCI 0 close is a MUX termination so we need to kick that 1469 back to userspace somehow */ 1470 } 1471 1472 /** 1473 * gsm_dlci_open - a DLCI has opened 1474 * @dlci: DLCI that opened 1475 * 1476 * Perform processing when moving a DLCI into open state. 1477 */ 1478 1479 static void gsm_dlci_open(struct gsm_dlci *dlci) 1480 { 1481 /* Note that SABM UA .. SABM UA first UA lost can mean that we go 1482 open -> open */ 1483 del_timer(&dlci->t1); 1484 /* This will let a tty open continue */ 1485 dlci->state = DLCI_OPEN; 1486 if (debug & 8) 1487 pr_debug("DLCI %d goes open.\n", dlci->addr); 1488 /* Register gsmtty driver,report gsmtty dev add uevent for user */ 1489 tty_register_device(gsm_tty_driver, dlci->addr, NULL); 1490 wake_up(&dlci->gsm->event); 1491 } 1492 1493 /** 1494 * gsm_dlci_t1 - T1 timer expiry 1495 * @t: timer contained in the DLCI that opened 1496 * 1497 * The T1 timer handles retransmits of control frames (essentially of 1498 * SABM and DISC). We resend the command until the retry count runs out 1499 * in which case an opening port goes back to closed and a closing port 1500 * is simply put into closed state (any further frames from the other 1501 * end will get a DM response) 1502 * 1503 * Some control dlci can stay in ADM mode with other dlci working just 1504 * fine. In that case we can just keep the control dlci open after the 1505 * DLCI_OPENING retries time out. 1506 */ 1507 1508 static void gsm_dlci_t1(struct timer_list *t) 1509 { 1510 struct gsm_dlci *dlci = from_timer(dlci, t, t1); 1511 struct gsm_mux *gsm = dlci->gsm; 1512 1513 switch (dlci->state) { 1514 case DLCI_OPENING: 1515 dlci->retries--; 1516 if (dlci->retries) { 1517 gsm_command(dlci->gsm, dlci->addr, SABM|PF); 1518 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100); 1519 } else if (!dlci->addr && gsm->control == (DM | PF)) { 1520 if (debug & 8) 1521 pr_info("DLCI %d opening in ADM mode.\n", 1522 dlci->addr); 1523 dlci->mode = DLCI_MODE_ADM; 1524 gsm_dlci_open(dlci); 1525 } else { 1526 gsm_dlci_begin_close(dlci); /* prevent half open link */ 1527 } 1528 1529 break; 1530 case DLCI_CLOSING: 1531 dlci->retries--; 1532 if (dlci->retries) { 1533 gsm_command(dlci->gsm, dlci->addr, DISC|PF); 1534 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100); 1535 } else 1536 gsm_dlci_close(dlci); 1537 break; 1538 default: 1539 pr_debug("%s: unhandled state: %d\n", __func__, dlci->state); 1540 break; 1541 } 1542 } 1543 1544 /** 1545 * gsm_dlci_begin_open - start channel open procedure 1546 * @dlci: DLCI to open 1547 * 1548 * Commence opening a DLCI from the Linux side. We issue SABM messages 1549 * to the modem which should then reply with a UA or ADM, at which point 1550 * we will move into open state. Opening is done asynchronously with retry 1551 * running off timers and the responses. 1552 */ 1553 1554 static void gsm_dlci_begin_open(struct gsm_dlci *dlci) 1555 { 1556 struct gsm_mux *gsm = dlci->gsm; 1557 if (dlci->state == DLCI_OPEN || dlci->state == DLCI_OPENING) 1558 return; 1559 dlci->retries = gsm->n2; 1560 dlci->state = DLCI_OPENING; 1561 gsm_command(dlci->gsm, dlci->addr, SABM|PF); 1562 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100); 1563 } 1564 1565 /** 1566 * gsm_dlci_begin_close - start channel open procedure 1567 * @dlci: DLCI to open 1568 * 1569 * Commence closing a DLCI from the Linux side. We issue DISC messages 1570 * to the modem which should then reply with a UA, at which point we 1571 * will move into closed state. Closing is done asynchronously with retry 1572 * off timers. We may also receive a DM reply from the other end which 1573 * indicates the channel was already closed. 1574 */ 1575 1576 static void gsm_dlci_begin_close(struct gsm_dlci *dlci) 1577 { 1578 struct gsm_mux *gsm = dlci->gsm; 1579 if (dlci->state == DLCI_CLOSED || dlci->state == DLCI_CLOSING) 1580 return; 1581 dlci->retries = gsm->n2; 1582 dlci->state = DLCI_CLOSING; 1583 gsm_command(dlci->gsm, dlci->addr, DISC|PF); 1584 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100); 1585 } 1586 1587 /** 1588 * gsm_dlci_data - data arrived 1589 * @dlci: channel 1590 * @data: block of bytes received 1591 * @clen: length of received block 1592 * 1593 * A UI or UIH frame has arrived which contains data for a channel 1594 * other than the control channel. If the relevant virtual tty is 1595 * open we shovel the bits down it, if not we drop them. 1596 */ 1597 1598 static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen) 1599 { 1600 /* krefs .. */ 1601 struct tty_port *port = &dlci->port; 1602 struct tty_struct *tty; 1603 unsigned int modem = 0; 1604 int len = clen; 1605 int slen = 0; 1606 1607 if (debug & 16) 1608 pr_debug("%d bytes for tty\n", len); 1609 switch (dlci->adaption) { 1610 /* Unsupported types */ 1611 case 4: /* Packetised interruptible data */ 1612 break; 1613 case 3: /* Packetised uininterruptible voice/data */ 1614 break; 1615 case 2: /* Asynchronous serial with line state in each frame */ 1616 while (gsm_read_ea(&modem, *data++) == 0) { 1617 len--; 1618 slen++; 1619 if (len == 0) 1620 return; 1621 } 1622 slen++; 1623 tty = tty_port_tty_get(port); 1624 if (tty) { 1625 gsm_process_modem(tty, dlci, modem, slen); 1626 tty_kref_put(tty); 1627 } 1628 fallthrough; 1629 case 1: /* Line state will go via DLCI 0 controls only */ 1630 default: 1631 tty_insert_flip_string(port, data, len); 1632 tty_flip_buffer_push(port); 1633 } 1634 } 1635 1636 /** 1637 * gsm_dlci_command - data arrived on control channel 1638 * @dlci: channel 1639 * @data: block of bytes received 1640 * @len: length of received block 1641 * 1642 * A UI or UIH frame has arrived which contains data for DLCI 0 the 1643 * control channel. This should contain a command EA followed by 1644 * control data bytes. The command EA contains a command/response bit 1645 * and we divide up the work accordingly. 1646 */ 1647 1648 static void gsm_dlci_command(struct gsm_dlci *dlci, const u8 *data, int len) 1649 { 1650 /* See what command is involved */ 1651 unsigned int command = 0; 1652 while (len-- > 0) { 1653 if (gsm_read_ea(&command, *data++) == 1) { 1654 int clen = *data++; 1655 len--; 1656 /* FIXME: this is properly an EA */ 1657 clen >>= 1; 1658 /* Malformed command ? */ 1659 if (clen > len) 1660 return; 1661 if (command & 1) 1662 gsm_control_message(dlci->gsm, command, 1663 data, clen); 1664 else 1665 gsm_control_response(dlci->gsm, command, 1666 data, clen); 1667 return; 1668 } 1669 } 1670 } 1671 1672 /* 1673 * Allocate/Free DLCI channels 1674 */ 1675 1676 /** 1677 * gsm_dlci_alloc - allocate a DLCI 1678 * @gsm: GSM mux 1679 * @addr: address of the DLCI 1680 * 1681 * Allocate and install a new DLCI object into the GSM mux. 1682 * 1683 * FIXME: review locking races 1684 */ 1685 1686 static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr) 1687 { 1688 struct gsm_dlci *dlci = kzalloc(sizeof(struct gsm_dlci), GFP_ATOMIC); 1689 if (dlci == NULL) 1690 return NULL; 1691 spin_lock_init(&dlci->lock); 1692 mutex_init(&dlci->mutex); 1693 if (kfifo_alloc(&dlci->fifo, 4096, GFP_KERNEL) < 0) { 1694 kfree(dlci); 1695 return NULL; 1696 } 1697 1698 skb_queue_head_init(&dlci->skb_list); 1699 timer_setup(&dlci->t1, gsm_dlci_t1, 0); 1700 tty_port_init(&dlci->port); 1701 dlci->port.ops = &gsm_port_ops; 1702 dlci->gsm = gsm; 1703 dlci->addr = addr; 1704 dlci->adaption = gsm->adaption; 1705 dlci->state = DLCI_CLOSED; 1706 if (addr) 1707 dlci->data = gsm_dlci_data; 1708 else 1709 dlci->data = gsm_dlci_command; 1710 gsm->dlci[addr] = dlci; 1711 return dlci; 1712 } 1713 1714 /** 1715 * gsm_dlci_free - free DLCI 1716 * @port: tty port for DLCI to free 1717 * 1718 * Free up a DLCI. 1719 * 1720 * Can sleep. 1721 */ 1722 static void gsm_dlci_free(struct tty_port *port) 1723 { 1724 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port); 1725 1726 del_timer_sync(&dlci->t1); 1727 dlci->gsm->dlci[dlci->addr] = NULL; 1728 kfifo_free(&dlci->fifo); 1729 while ((dlci->skb = skb_dequeue(&dlci->skb_list))) 1730 dev_kfree_skb(dlci->skb); 1731 kfree(dlci); 1732 } 1733 1734 static inline void dlci_get(struct gsm_dlci *dlci) 1735 { 1736 tty_port_get(&dlci->port); 1737 } 1738 1739 static inline void dlci_put(struct gsm_dlci *dlci) 1740 { 1741 tty_port_put(&dlci->port); 1742 } 1743 1744 static void gsm_destroy_network(struct gsm_dlci *dlci); 1745 1746 /** 1747 * gsm_dlci_release - release DLCI 1748 * @dlci: DLCI to destroy 1749 * 1750 * Release a DLCI. Actual free is deferred until either 1751 * mux is closed or tty is closed - whichever is last. 1752 * 1753 * Can sleep. 1754 */ 1755 static void gsm_dlci_release(struct gsm_dlci *dlci) 1756 { 1757 struct tty_struct *tty = tty_port_tty_get(&dlci->port); 1758 if (tty) { 1759 mutex_lock(&dlci->mutex); 1760 gsm_destroy_network(dlci); 1761 mutex_unlock(&dlci->mutex); 1762 1763 /* We cannot use tty_hangup() because in tty_kref_put() the tty 1764 * driver assumes that the hangup queue is free and reuses it to 1765 * queue release_one_tty() -> NULL pointer panic in 1766 * process_one_work(). 1767 */ 1768 tty_vhangup(tty); 1769 1770 tty_port_tty_set(&dlci->port, NULL); 1771 tty_kref_put(tty); 1772 } 1773 dlci->state = DLCI_CLOSED; 1774 dlci_put(dlci); 1775 } 1776 1777 /* 1778 * LAPBish link layer logic 1779 */ 1780 1781 /** 1782 * gsm_queue - a GSM frame is ready to process 1783 * @gsm: pointer to our gsm mux 1784 * 1785 * At this point in time a frame has arrived and been demangled from 1786 * the line encoding. All the differences between the encodings have 1787 * been handled below us and the frame is unpacked into the structures. 1788 * The fcs holds the header FCS but any data FCS must be added here. 1789 */ 1790 1791 static void gsm_queue(struct gsm_mux *gsm) 1792 { 1793 struct gsm_dlci *dlci; 1794 u8 cr; 1795 int address; 1796 int i, j, k, address_tmp; 1797 /* We have to sneak a look at the packet body to do the FCS. 1798 A somewhat layering violation in the spec */ 1799 1800 if ((gsm->control & ~PF) == UI) 1801 gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf, gsm->len); 1802 if (gsm->encoding == 0) { 1803 /* WARNING: gsm->received_fcs is used for 1804 gsm->encoding = 0 only. 1805 In this case it contain the last piece of data 1806 required to generate final CRC */ 1807 gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs); 1808 } 1809 if (gsm->fcs != GOOD_FCS) { 1810 gsm->bad_fcs++; 1811 if (debug & 4) 1812 pr_debug("BAD FCS %02x\n", gsm->fcs); 1813 return; 1814 } 1815 address = gsm->address >> 1; 1816 if (address >= NUM_DLCI) 1817 goto invalid; 1818 1819 cr = gsm->address & 1; /* C/R bit */ 1820 cr ^= gsm->initiator ? 0 : 1; /* Flip so 1 always means command */ 1821 1822 gsm_print_packet("<--", address, cr, gsm->control, gsm->buf, gsm->len); 1823 1824 dlci = gsm->dlci[address]; 1825 1826 switch (gsm->control) { 1827 case SABM|PF: 1828 if (cr == 1) 1829 goto invalid; 1830 if (dlci == NULL) 1831 dlci = gsm_dlci_alloc(gsm, address); 1832 if (dlci == NULL) 1833 return; 1834 if (dlci->dead) 1835 gsm_response(gsm, address, DM|PF); 1836 else { 1837 gsm_response(gsm, address, UA|PF); 1838 gsm_dlci_open(dlci); 1839 /* Save dlci open address */ 1840 if (address) { 1841 addr_open[addr_cnt] = address; 1842 addr_cnt++; 1843 } 1844 } 1845 break; 1846 case DISC|PF: 1847 if (cr == 1) 1848 goto invalid; 1849 if (dlci == NULL || dlci->state == DLCI_CLOSED) { 1850 gsm_response(gsm, address, DM|PF); 1851 return; 1852 } 1853 /* Real close complete */ 1854 if (!address) { 1855 if (addr_cnt > 0) { 1856 for (i = 0; i < addr_cnt; i++) { 1857 address = addr_open[i]; 1858 dlci = gsm->dlci[address]; 1859 gsm_dlci_close(dlci); 1860 addr_open[i] = 0; 1861 } 1862 } 1863 dlci = gsm->dlci[0]; 1864 gsm_dlci_close(dlci); 1865 addr_cnt = 0; 1866 gsm_response(gsm, 0, UA|PF); 1867 } else { 1868 gsm_response(gsm, address, UA|PF); 1869 gsm_dlci_close(dlci); 1870 /* clear dlci address */ 1871 for (j = 0; j < addr_cnt; j++) { 1872 address_tmp = addr_open[j]; 1873 if (address_tmp == address) { 1874 for (k = j; k < addr_cnt; k++) 1875 addr_open[k] = addr_open[k+1]; 1876 addr_cnt--; 1877 break; 1878 } 1879 } 1880 } 1881 break; 1882 case UA: 1883 case UA|PF: 1884 if (cr == 0 || dlci == NULL) 1885 break; 1886 switch (dlci->state) { 1887 case DLCI_CLOSING: 1888 gsm_dlci_close(dlci); 1889 break; 1890 case DLCI_OPENING: 1891 gsm_dlci_open(dlci); 1892 break; 1893 default: 1894 pr_debug("%s: unhandled state: %d\n", __func__, 1895 dlci->state); 1896 break; 1897 } 1898 break; 1899 case DM: /* DM can be valid unsolicited */ 1900 case DM|PF: 1901 if (cr) 1902 goto invalid; 1903 if (dlci == NULL) 1904 return; 1905 gsm_dlci_close(dlci); 1906 break; 1907 case UI: 1908 case UI|PF: 1909 case UIH: 1910 case UIH|PF: 1911 #if 0 1912 if (cr) 1913 goto invalid; 1914 #endif 1915 if (dlci == NULL || dlci->state != DLCI_OPEN) { 1916 gsm_command(gsm, address, DM|PF); 1917 return; 1918 } 1919 dlci->data(dlci, gsm->buf, gsm->len); 1920 break; 1921 default: 1922 goto invalid; 1923 } 1924 return; 1925 invalid: 1926 gsm->malformed++; 1927 return; 1928 } 1929 1930 1931 /** 1932 * gsm0_receive - perform processing for non-transparency 1933 * @gsm: gsm data for this ldisc instance 1934 * @c: character 1935 * 1936 * Receive bytes in gsm mode 0 1937 */ 1938 1939 static void gsm0_receive(struct gsm_mux *gsm, unsigned char c) 1940 { 1941 unsigned int len; 1942 1943 switch (gsm->state) { 1944 case GSM_SEARCH: /* SOF marker */ 1945 if (c == GSM0_SOF) { 1946 gsm->state = GSM_ADDRESS; 1947 gsm->address = 0; 1948 gsm->len = 0; 1949 gsm->fcs = INIT_FCS; 1950 } 1951 break; 1952 case GSM_ADDRESS: /* Address EA */ 1953 gsm->fcs = gsm_fcs_add(gsm->fcs, c); 1954 if (gsm_read_ea(&gsm->address, c)) 1955 gsm->state = GSM_CONTROL; 1956 break; 1957 case GSM_CONTROL: /* Control Byte */ 1958 gsm->fcs = gsm_fcs_add(gsm->fcs, c); 1959 gsm->control = c; 1960 gsm->state = GSM_LEN0; 1961 break; 1962 case GSM_LEN0: /* Length EA */ 1963 gsm->fcs = gsm_fcs_add(gsm->fcs, c); 1964 if (gsm_read_ea(&gsm->len, c)) { 1965 if (gsm->len > gsm->mru) { 1966 gsm->bad_size++; 1967 gsm->state = GSM_SEARCH; 1968 break; 1969 } 1970 gsm->count = 0; 1971 if (!gsm->len) 1972 gsm->state = GSM_FCS; 1973 else 1974 gsm->state = GSM_DATA; 1975 break; 1976 } 1977 gsm->state = GSM_LEN1; 1978 break; 1979 case GSM_LEN1: 1980 gsm->fcs = gsm_fcs_add(gsm->fcs, c); 1981 len = c; 1982 gsm->len |= len << 7; 1983 if (gsm->len > gsm->mru) { 1984 gsm->bad_size++; 1985 gsm->state = GSM_SEARCH; 1986 break; 1987 } 1988 gsm->count = 0; 1989 if (!gsm->len) 1990 gsm->state = GSM_FCS; 1991 else 1992 gsm->state = GSM_DATA; 1993 break; 1994 case GSM_DATA: /* Data */ 1995 gsm->buf[gsm->count++] = c; 1996 if (gsm->count == gsm->len) 1997 gsm->state = GSM_FCS; 1998 break; 1999 case GSM_FCS: /* FCS follows the packet */ 2000 gsm->received_fcs = c; 2001 gsm_queue(gsm); 2002 gsm->state = GSM_SSOF; 2003 break; 2004 case GSM_SSOF: 2005 if (c == GSM0_SOF) { 2006 gsm->state = GSM_SEARCH; 2007 break; 2008 } 2009 break; 2010 default: 2011 pr_debug("%s: unhandled state: %d\n", __func__, gsm->state); 2012 break; 2013 } 2014 } 2015 2016 /** 2017 * gsm1_receive - perform processing for non-transparency 2018 * @gsm: gsm data for this ldisc instance 2019 * @c: character 2020 * 2021 * Receive bytes in mode 1 (Advanced option) 2022 */ 2023 2024 static void gsm1_receive(struct gsm_mux *gsm, unsigned char c) 2025 { 2026 if (c == GSM1_SOF) { 2027 /* EOF is only valid in frame if we have got to the data state 2028 and received at least one byte (the FCS) */ 2029 if (gsm->state == GSM_DATA && gsm->count) { 2030 /* Extract the FCS */ 2031 gsm->count--; 2032 gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]); 2033 gsm->len = gsm->count; 2034 gsm_queue(gsm); 2035 gsm->state = GSM_START; 2036 return; 2037 } 2038 /* Any partial frame was a runt so go back to start */ 2039 if (gsm->state != GSM_START) { 2040 gsm->malformed++; 2041 gsm->state = GSM_START; 2042 } 2043 /* A SOF in GSM_START means we are still reading idling or 2044 framing bytes */ 2045 return; 2046 } 2047 2048 if (c == GSM1_ESCAPE) { 2049 gsm->escape = true; 2050 return; 2051 } 2052 2053 /* Only an unescaped SOF gets us out of GSM search */ 2054 if (gsm->state == GSM_SEARCH) 2055 return; 2056 2057 if (gsm->escape) { 2058 c ^= GSM1_ESCAPE_BITS; 2059 gsm->escape = false; 2060 } 2061 switch (gsm->state) { 2062 case GSM_START: /* First byte after SOF */ 2063 gsm->address = 0; 2064 gsm->state = GSM_ADDRESS; 2065 gsm->fcs = INIT_FCS; 2066 fallthrough; 2067 case GSM_ADDRESS: /* Address continuation */ 2068 gsm->fcs = gsm_fcs_add(gsm->fcs, c); 2069 if (gsm_read_ea(&gsm->address, c)) 2070 gsm->state = GSM_CONTROL; 2071 break; 2072 case GSM_CONTROL: /* Control Byte */ 2073 gsm->fcs = gsm_fcs_add(gsm->fcs, c); 2074 gsm->control = c; 2075 gsm->count = 0; 2076 gsm->state = GSM_DATA; 2077 break; 2078 case GSM_DATA: /* Data */ 2079 if (gsm->count > gsm->mru) { /* Allow one for the FCS */ 2080 gsm->state = GSM_OVERRUN; 2081 gsm->bad_size++; 2082 } else 2083 gsm->buf[gsm->count++] = c; 2084 break; 2085 case GSM_OVERRUN: /* Over-long - eg a dropped SOF */ 2086 break; 2087 default: 2088 pr_debug("%s: unhandled state: %d\n", __func__, gsm->state); 2089 break; 2090 } 2091 } 2092 2093 /** 2094 * gsm_error - handle tty error 2095 * @gsm: ldisc data 2096 * 2097 * Handle an error in the receipt of data for a frame. Currently we just 2098 * go back to hunting for a SOF. 2099 * 2100 * FIXME: better diagnostics ? 2101 */ 2102 2103 static void gsm_error(struct gsm_mux *gsm) 2104 { 2105 gsm->state = GSM_SEARCH; 2106 gsm->io_error++; 2107 } 2108 2109 static int gsm_disconnect(struct gsm_mux *gsm) 2110 { 2111 struct gsm_dlci *dlci = gsm->dlci[0]; 2112 struct gsm_control *gc; 2113 2114 if (!dlci) 2115 return 0; 2116 2117 /* In theory disconnecting DLCI 0 is sufficient but for some 2118 modems this is apparently not the case. */ 2119 gc = gsm_control_send(gsm, CMD_CLD, NULL, 0); 2120 if (gc) 2121 gsm_control_wait(gsm, gc); 2122 2123 del_timer_sync(&gsm->t2_timer); 2124 /* Now we are sure T2 has stopped */ 2125 2126 gsm_dlci_begin_close(dlci); 2127 wait_event_interruptible(gsm->event, 2128 dlci->state == DLCI_CLOSED); 2129 2130 if (signal_pending(current)) 2131 return -EINTR; 2132 2133 return 0; 2134 } 2135 2136 /** 2137 * gsm_cleanup_mux - generic GSM protocol cleanup 2138 * @gsm: our mux 2139 * 2140 * Clean up the bits of the mux which are the same for all framing 2141 * protocols. Remove the mux from the mux table, stop all the timers 2142 * and then shut down each device hanging up the channels as we go. 2143 */ 2144 2145 static void gsm_cleanup_mux(struct gsm_mux *gsm) 2146 { 2147 int i; 2148 struct gsm_dlci *dlci = gsm->dlci[0]; 2149 struct gsm_msg *txq, *ntxq; 2150 2151 gsm->dead = true; 2152 2153 spin_lock(&gsm_mux_lock); 2154 for (i = 0; i < MAX_MUX; i++) { 2155 if (gsm_mux[i] == gsm) { 2156 gsm_mux[i] = NULL; 2157 break; 2158 } 2159 } 2160 spin_unlock(&gsm_mux_lock); 2161 /* open failed before registering => nothing to do */ 2162 if (i == MAX_MUX) 2163 return; 2164 2165 del_timer_sync(&gsm->t2_timer); 2166 /* Now we are sure T2 has stopped */ 2167 if (dlci) 2168 dlci->dead = true; 2169 2170 /* Free up any link layer users */ 2171 mutex_lock(&gsm->mutex); 2172 for (i = 0; i < NUM_DLCI; i++) 2173 if (gsm->dlci[i]) 2174 gsm_dlci_release(gsm->dlci[i]); 2175 mutex_unlock(&gsm->mutex); 2176 /* Now wipe the queues */ 2177 list_for_each_entry_safe(txq, ntxq, &gsm->tx_list, list) 2178 kfree(txq); 2179 INIT_LIST_HEAD(&gsm->tx_list); 2180 } 2181 2182 /** 2183 * gsm_activate_mux - generic GSM setup 2184 * @gsm: our mux 2185 * 2186 * Set up the bits of the mux which are the same for all framing 2187 * protocols. Add the mux to the mux table so it can be opened and 2188 * finally kick off connecting to DLCI 0 on the modem. 2189 */ 2190 2191 static int gsm_activate_mux(struct gsm_mux *gsm) 2192 { 2193 struct gsm_dlci *dlci; 2194 int i = 0; 2195 2196 timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0); 2197 init_waitqueue_head(&gsm->event); 2198 spin_lock_init(&gsm->control_lock); 2199 spin_lock_init(&gsm->tx_lock); 2200 2201 if (gsm->encoding == 0) 2202 gsm->receive = gsm0_receive; 2203 else 2204 gsm->receive = gsm1_receive; 2205 2206 spin_lock(&gsm_mux_lock); 2207 for (i = 0; i < MAX_MUX; i++) { 2208 if (gsm_mux[i] == NULL) { 2209 gsm->num = i; 2210 gsm_mux[i] = gsm; 2211 break; 2212 } 2213 } 2214 spin_unlock(&gsm_mux_lock); 2215 if (i == MAX_MUX) 2216 return -EBUSY; 2217 2218 dlci = gsm_dlci_alloc(gsm, 0); 2219 if (dlci == NULL) 2220 return -ENOMEM; 2221 gsm->dead = false; /* Tty opens are now permissible */ 2222 return 0; 2223 } 2224 2225 /** 2226 * gsm_free_mux - free up a mux 2227 * @gsm: mux to free 2228 * 2229 * Dispose of allocated resources for a dead mux 2230 */ 2231 static void gsm_free_mux(struct gsm_mux *gsm) 2232 { 2233 kfree(gsm->txframe); 2234 kfree(gsm->buf); 2235 kfree(gsm); 2236 } 2237 2238 /** 2239 * gsm_free_muxr - free up a mux 2240 * @ref: kreference to the mux to free 2241 * 2242 * Dispose of allocated resources for a dead mux 2243 */ 2244 static void gsm_free_muxr(struct kref *ref) 2245 { 2246 struct gsm_mux *gsm = container_of(ref, struct gsm_mux, ref); 2247 gsm_free_mux(gsm); 2248 } 2249 2250 static inline void mux_get(struct gsm_mux *gsm) 2251 { 2252 kref_get(&gsm->ref); 2253 } 2254 2255 static inline void mux_put(struct gsm_mux *gsm) 2256 { 2257 kref_put(&gsm->ref, gsm_free_muxr); 2258 } 2259 2260 static inline unsigned int mux_num_to_base(struct gsm_mux *gsm) 2261 { 2262 return gsm->num * NUM_DLCI; 2263 } 2264 2265 static inline unsigned int mux_line_to_num(unsigned int line) 2266 { 2267 return line / NUM_DLCI; 2268 } 2269 2270 /** 2271 * gsm_alloc_mux - allocate a mux 2272 * 2273 * Creates a new mux ready for activation. 2274 */ 2275 2276 static struct gsm_mux *gsm_alloc_mux(void) 2277 { 2278 struct gsm_mux *gsm = kzalloc(sizeof(struct gsm_mux), GFP_KERNEL); 2279 if (gsm == NULL) 2280 return NULL; 2281 gsm->buf = kmalloc(MAX_MRU + 1, GFP_KERNEL); 2282 if (gsm->buf == NULL) { 2283 kfree(gsm); 2284 return NULL; 2285 } 2286 gsm->txframe = kmalloc(2 * MAX_MRU + 2, GFP_KERNEL); 2287 if (gsm->txframe == NULL) { 2288 kfree(gsm->buf); 2289 kfree(gsm); 2290 return NULL; 2291 } 2292 spin_lock_init(&gsm->lock); 2293 mutex_init(&gsm->mutex); 2294 kref_init(&gsm->ref); 2295 INIT_LIST_HEAD(&gsm->tx_list); 2296 2297 gsm->t1 = T1; 2298 gsm->t2 = T2; 2299 gsm->n2 = N2; 2300 gsm->ftype = UIH; 2301 gsm->adaption = 1; 2302 gsm->encoding = 1; 2303 gsm->mru = 64; /* Default to encoding 1 so these should be 64 */ 2304 gsm->mtu = 64; 2305 gsm->dead = true; /* Avoid early tty opens */ 2306 2307 return gsm; 2308 } 2309 2310 static void gsm_copy_config_values(struct gsm_mux *gsm, 2311 struct gsm_config *c) 2312 { 2313 memset(c, 0, sizeof(*c)); 2314 c->adaption = gsm->adaption; 2315 c->encapsulation = gsm->encoding; 2316 c->initiator = gsm->initiator; 2317 c->t1 = gsm->t1; 2318 c->t2 = gsm->t2; 2319 c->t3 = 0; /* Not supported */ 2320 c->n2 = gsm->n2; 2321 if (gsm->ftype == UIH) 2322 c->i = 1; 2323 else 2324 c->i = 2; 2325 pr_debug("Ftype %d i %d\n", gsm->ftype, c->i); 2326 c->mru = gsm->mru; 2327 c->mtu = gsm->mtu; 2328 c->k = 0; 2329 } 2330 2331 static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c) 2332 { 2333 int need_close = 0; 2334 int need_restart = 0; 2335 2336 /* Stuff we don't support yet - UI or I frame transport, windowing */ 2337 if ((c->adaption != 1 && c->adaption != 2) || c->k) 2338 return -EOPNOTSUPP; 2339 /* Check the MRU/MTU range looks sane */ 2340 if (c->mru > MAX_MRU || c->mtu > MAX_MTU || c->mru < 8 || c->mtu < 8) 2341 return -EINVAL; 2342 if (c->n2 < 3) 2343 return -EINVAL; 2344 if (c->encapsulation > 1) /* Basic, advanced, no I */ 2345 return -EINVAL; 2346 if (c->initiator > 1) 2347 return -EINVAL; 2348 if (c->i == 0 || c->i > 2) /* UIH and UI only */ 2349 return -EINVAL; 2350 /* 2351 * See what is needed for reconfiguration 2352 */ 2353 2354 /* Timing fields */ 2355 if (c->t1 != 0 && c->t1 != gsm->t1) 2356 need_restart = 1; 2357 if (c->t2 != 0 && c->t2 != gsm->t2) 2358 need_restart = 1; 2359 if (c->encapsulation != gsm->encoding) 2360 need_restart = 1; 2361 if (c->adaption != gsm->adaption) 2362 need_restart = 1; 2363 /* Requires care */ 2364 if (c->initiator != gsm->initiator) 2365 need_close = 1; 2366 if (c->mru != gsm->mru) 2367 need_restart = 1; 2368 if (c->mtu != gsm->mtu) 2369 need_restart = 1; 2370 2371 /* 2372 * Close down what is needed, restart and initiate the new 2373 * configuration 2374 */ 2375 2376 if (gsm->initiator && (need_close || need_restart)) { 2377 int ret; 2378 2379 ret = gsm_disconnect(gsm); 2380 2381 if (ret) 2382 return ret; 2383 } 2384 if (need_restart) 2385 gsm_cleanup_mux(gsm); 2386 2387 gsm->initiator = c->initiator; 2388 gsm->mru = c->mru; 2389 gsm->mtu = c->mtu; 2390 gsm->encoding = c->encapsulation; 2391 gsm->adaption = c->adaption; 2392 gsm->n2 = c->n2; 2393 2394 if (c->i == 1) 2395 gsm->ftype = UIH; 2396 else if (c->i == 2) 2397 gsm->ftype = UI; 2398 2399 if (c->t1) 2400 gsm->t1 = c->t1; 2401 if (c->t2) 2402 gsm->t2 = c->t2; 2403 2404 /* 2405 * FIXME: We need to separate activation/deactivation from adding 2406 * and removing from the mux array 2407 */ 2408 if (need_restart) 2409 gsm_activate_mux(gsm); 2410 if (gsm->initiator && need_close) 2411 gsm_dlci_begin_open(gsm->dlci[0]); 2412 return 0; 2413 } 2414 2415 /** 2416 * gsmld_output - write to link 2417 * @gsm: our mux 2418 * @data: bytes to output 2419 * @len: size 2420 * 2421 * Write a block of data from the GSM mux to the data channel. This 2422 * will eventually be serialized from above but at the moment isn't. 2423 */ 2424 2425 static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len) 2426 { 2427 if (tty_write_room(gsm->tty) < len) { 2428 set_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags); 2429 return -ENOSPC; 2430 } 2431 if (debug & 4) 2432 print_hex_dump_bytes("gsmld_output: ", DUMP_PREFIX_OFFSET, 2433 data, len); 2434 return gsm->tty->ops->write(gsm->tty, data, len); 2435 } 2436 2437 /** 2438 * gsmld_attach_gsm - mode set up 2439 * @tty: our tty structure 2440 * @gsm: our mux 2441 * 2442 * Set up the MUX for basic mode and commence connecting to the 2443 * modem. Currently called from the line discipline set up but 2444 * will need moving to an ioctl path. 2445 */ 2446 2447 static int gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm) 2448 { 2449 unsigned int base; 2450 int ret, i; 2451 2452 gsm->tty = tty_kref_get(tty); 2453 ret = gsm_activate_mux(gsm); 2454 if (ret != 0) 2455 tty_kref_put(gsm->tty); 2456 else { 2457 /* Don't register device 0 - this is the control channel and not 2458 a usable tty interface */ 2459 if (gsm->initiator) { 2460 base = mux_num_to_base(gsm); /* Base for this MUX */ 2461 for (i = 1; i < NUM_DLCI; i++) { 2462 struct device *dev; 2463 2464 dev = tty_register_device(gsm_tty_driver, 2465 base + i, NULL); 2466 if (IS_ERR(dev)) { 2467 for (i--; i >= 1; i--) 2468 tty_unregister_device(gsm_tty_driver, 2469 base + i); 2470 return PTR_ERR(dev); 2471 } 2472 } 2473 } 2474 } 2475 return ret; 2476 } 2477 2478 2479 /** 2480 * gsmld_detach_gsm - stop doing 0710 mux 2481 * @tty: tty attached to the mux 2482 * @gsm: mux 2483 * 2484 * Shutdown and then clean up the resources used by the line discipline 2485 */ 2486 2487 static void gsmld_detach_gsm(struct tty_struct *tty, struct gsm_mux *gsm) 2488 { 2489 unsigned int base = mux_num_to_base(gsm); /* Base for this MUX */ 2490 int i; 2491 2492 WARN_ON(tty != gsm->tty); 2493 if (gsm->initiator) { 2494 for (i = 1; i < NUM_DLCI; i++) 2495 tty_unregister_device(gsm_tty_driver, base + i); 2496 } 2497 gsm_cleanup_mux(gsm); 2498 tty_kref_put(gsm->tty); 2499 gsm->tty = NULL; 2500 } 2501 2502 static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp, 2503 const char *fp, int count) 2504 { 2505 struct gsm_mux *gsm = tty->disc_data; 2506 char flags = TTY_NORMAL; 2507 2508 if (debug & 4) 2509 print_hex_dump_bytes("gsmld_receive: ", DUMP_PREFIX_OFFSET, 2510 cp, count); 2511 2512 for (; count; count--, cp++) { 2513 if (fp) 2514 flags = *fp++; 2515 switch (flags) { 2516 case TTY_NORMAL: 2517 gsm->receive(gsm, *cp); 2518 break; 2519 case TTY_OVERRUN: 2520 case TTY_BREAK: 2521 case TTY_PARITY: 2522 case TTY_FRAME: 2523 gsm_error(gsm); 2524 break; 2525 default: 2526 WARN_ONCE(1, "%s: unknown flag %d\n", 2527 tty_name(tty), flags); 2528 break; 2529 } 2530 } 2531 /* FASYNC if needed ? */ 2532 /* If clogged call tty_throttle(tty); */ 2533 } 2534 2535 /** 2536 * gsmld_flush_buffer - clean input queue 2537 * @tty: terminal device 2538 * 2539 * Flush the input buffer. Called when the line discipline is 2540 * being closed, when the tty layer wants the buffer flushed (eg 2541 * at hangup). 2542 */ 2543 2544 static void gsmld_flush_buffer(struct tty_struct *tty) 2545 { 2546 } 2547 2548 /** 2549 * gsmld_close - close the ldisc for this tty 2550 * @tty: device 2551 * 2552 * Called from the terminal layer when this line discipline is 2553 * being shut down, either because of a close or becsuse of a 2554 * discipline change. The function will not be called while other 2555 * ldisc methods are in progress. 2556 */ 2557 2558 static void gsmld_close(struct tty_struct *tty) 2559 { 2560 struct gsm_mux *gsm = tty->disc_data; 2561 2562 gsmld_detach_gsm(tty, gsm); 2563 2564 gsmld_flush_buffer(tty); 2565 /* Do other clean up here */ 2566 mux_put(gsm); 2567 } 2568 2569 /** 2570 * gsmld_open - open an ldisc 2571 * @tty: terminal to open 2572 * 2573 * Called when this line discipline is being attached to the 2574 * terminal device. Can sleep. Called serialized so that no 2575 * other events will occur in parallel. No further open will occur 2576 * until a close. 2577 */ 2578 2579 static int gsmld_open(struct tty_struct *tty) 2580 { 2581 struct gsm_mux *gsm; 2582 int ret; 2583 2584 if (tty->ops->write == NULL) 2585 return -EINVAL; 2586 2587 /* Attach our ldisc data */ 2588 gsm = gsm_alloc_mux(); 2589 if (gsm == NULL) 2590 return -ENOMEM; 2591 2592 tty->disc_data = gsm; 2593 tty->receive_room = 65536; 2594 2595 /* Attach the initial passive connection */ 2596 gsm->encoding = 1; 2597 2598 ret = gsmld_attach_gsm(tty, gsm); 2599 if (ret != 0) { 2600 gsm_cleanup_mux(gsm); 2601 mux_put(gsm); 2602 } 2603 return ret; 2604 } 2605 2606 /** 2607 * gsmld_write_wakeup - asynchronous I/O notifier 2608 * @tty: tty device 2609 * 2610 * Required for the ptys, serial driver etc. since processes 2611 * that attach themselves to the master and rely on ASYNC 2612 * IO must be woken up 2613 */ 2614 2615 static void gsmld_write_wakeup(struct tty_struct *tty) 2616 { 2617 struct gsm_mux *gsm = tty->disc_data; 2618 unsigned long flags; 2619 2620 /* Queue poll */ 2621 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 2622 spin_lock_irqsave(&gsm->tx_lock, flags); 2623 gsm_data_kick(gsm, NULL); 2624 if (gsm->tx_bytes < TX_THRESH_LO) { 2625 gsm_dlci_data_sweep(gsm); 2626 } 2627 spin_unlock_irqrestore(&gsm->tx_lock, flags); 2628 } 2629 2630 /** 2631 * gsmld_read - read function for tty 2632 * @tty: tty device 2633 * @file: file object 2634 * @buf: userspace buffer pointer 2635 * @nr: size of I/O 2636 * @cookie: unused 2637 * @offset: unused 2638 * 2639 * Perform reads for the line discipline. We are guaranteed that the 2640 * line discipline will not be closed under us but we may get multiple 2641 * parallel readers and must handle this ourselves. We may also get 2642 * a hangup. Always called in user context, may sleep. 2643 * 2644 * This code must be sure never to sleep through a hangup. 2645 */ 2646 2647 static ssize_t gsmld_read(struct tty_struct *tty, struct file *file, 2648 unsigned char *buf, size_t nr, 2649 void **cookie, unsigned long offset) 2650 { 2651 return -EOPNOTSUPP; 2652 } 2653 2654 /** 2655 * gsmld_write - write function for tty 2656 * @tty: tty device 2657 * @file: file object 2658 * @buf: userspace buffer pointer 2659 * @nr: size of I/O 2660 * 2661 * Called when the owner of the device wants to send a frame 2662 * itself (or some other control data). The data is transferred 2663 * as-is and must be properly framed and checksummed as appropriate 2664 * by userspace. Frames are either sent whole or not at all as this 2665 * avoids pain user side. 2666 */ 2667 2668 static ssize_t gsmld_write(struct tty_struct *tty, struct file *file, 2669 const unsigned char *buf, size_t nr) 2670 { 2671 int space = tty_write_room(tty); 2672 if (space >= nr) 2673 return tty->ops->write(tty, buf, nr); 2674 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 2675 return -ENOBUFS; 2676 } 2677 2678 /** 2679 * gsmld_poll - poll method for N_GSM0710 2680 * @tty: terminal device 2681 * @file: file accessing it 2682 * @wait: poll table 2683 * 2684 * Called when the line discipline is asked to poll() for data or 2685 * for special events. This code is not serialized with respect to 2686 * other events save open/close. 2687 * 2688 * This code must be sure never to sleep through a hangup. 2689 * Called without the kernel lock held - fine 2690 */ 2691 2692 static __poll_t gsmld_poll(struct tty_struct *tty, struct file *file, 2693 poll_table *wait) 2694 { 2695 __poll_t mask = 0; 2696 struct gsm_mux *gsm = tty->disc_data; 2697 2698 poll_wait(file, &tty->read_wait, wait); 2699 poll_wait(file, &tty->write_wait, wait); 2700 if (tty_hung_up_p(file)) 2701 mask |= EPOLLHUP; 2702 if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0) 2703 mask |= EPOLLOUT | EPOLLWRNORM; 2704 if (gsm->dead) 2705 mask |= EPOLLHUP; 2706 return mask; 2707 } 2708 2709 static int gsmld_ioctl(struct tty_struct *tty, unsigned int cmd, 2710 unsigned long arg) 2711 { 2712 struct gsm_config c; 2713 struct gsm_mux *gsm = tty->disc_data; 2714 unsigned int base; 2715 2716 switch (cmd) { 2717 case GSMIOC_GETCONF: 2718 gsm_copy_config_values(gsm, &c); 2719 if (copy_to_user((void __user *)arg, &c, sizeof(c))) 2720 return -EFAULT; 2721 return 0; 2722 case GSMIOC_SETCONF: 2723 if (copy_from_user(&c, (void __user *)arg, sizeof(c))) 2724 return -EFAULT; 2725 return gsm_config(gsm, &c); 2726 case GSMIOC_GETFIRST: 2727 base = mux_num_to_base(gsm); 2728 return put_user(base + 1, (__u32 __user *)arg); 2729 default: 2730 return n_tty_ioctl_helper(tty, cmd, arg); 2731 } 2732 } 2733 2734 /* 2735 * Network interface 2736 * 2737 */ 2738 2739 static int gsm_mux_net_open(struct net_device *net) 2740 { 2741 pr_debug("%s called\n", __func__); 2742 netif_start_queue(net); 2743 return 0; 2744 } 2745 2746 static int gsm_mux_net_close(struct net_device *net) 2747 { 2748 netif_stop_queue(net); 2749 return 0; 2750 } 2751 2752 static void dlci_net_free(struct gsm_dlci *dlci) 2753 { 2754 if (!dlci->net) { 2755 WARN_ON(1); 2756 return; 2757 } 2758 dlci->adaption = dlci->prev_adaption; 2759 dlci->data = dlci->prev_data; 2760 free_netdev(dlci->net); 2761 dlci->net = NULL; 2762 } 2763 static void net_free(struct kref *ref) 2764 { 2765 struct gsm_mux_net *mux_net; 2766 struct gsm_dlci *dlci; 2767 2768 mux_net = container_of(ref, struct gsm_mux_net, ref); 2769 dlci = mux_net->dlci; 2770 2771 if (dlci->net) { 2772 unregister_netdev(dlci->net); 2773 dlci_net_free(dlci); 2774 } 2775 } 2776 2777 static inline void muxnet_get(struct gsm_mux_net *mux_net) 2778 { 2779 kref_get(&mux_net->ref); 2780 } 2781 2782 static inline void muxnet_put(struct gsm_mux_net *mux_net) 2783 { 2784 kref_put(&mux_net->ref, net_free); 2785 } 2786 2787 static netdev_tx_t gsm_mux_net_start_xmit(struct sk_buff *skb, 2788 struct net_device *net) 2789 { 2790 struct gsm_mux_net *mux_net = netdev_priv(net); 2791 struct gsm_dlci *dlci = mux_net->dlci; 2792 muxnet_get(mux_net); 2793 2794 skb_queue_head(&dlci->skb_list, skb); 2795 net->stats.tx_packets++; 2796 net->stats.tx_bytes += skb->len; 2797 gsm_dlci_data_kick(dlci); 2798 /* And tell the kernel when the last transmit started. */ 2799 netif_trans_update(net); 2800 muxnet_put(mux_net); 2801 return NETDEV_TX_OK; 2802 } 2803 2804 /* called when a packet did not ack after watchdogtimeout */ 2805 static void gsm_mux_net_tx_timeout(struct net_device *net, unsigned int txqueue) 2806 { 2807 /* Tell syslog we are hosed. */ 2808 dev_dbg(&net->dev, "Tx timed out.\n"); 2809 2810 /* Update statistics */ 2811 net->stats.tx_errors++; 2812 } 2813 2814 static void gsm_mux_rx_netchar(struct gsm_dlci *dlci, 2815 const unsigned char *in_buf, int size) 2816 { 2817 struct net_device *net = dlci->net; 2818 struct sk_buff *skb; 2819 struct gsm_mux_net *mux_net = netdev_priv(net); 2820 muxnet_get(mux_net); 2821 2822 /* Allocate an sk_buff */ 2823 skb = dev_alloc_skb(size + NET_IP_ALIGN); 2824 if (!skb) { 2825 /* We got no receive buffer. */ 2826 net->stats.rx_dropped++; 2827 muxnet_put(mux_net); 2828 return; 2829 } 2830 skb_reserve(skb, NET_IP_ALIGN); 2831 skb_put_data(skb, in_buf, size); 2832 2833 skb->dev = net; 2834 skb->protocol = htons(ETH_P_IP); 2835 2836 /* Ship it off to the kernel */ 2837 netif_rx(skb); 2838 2839 /* update out statistics */ 2840 net->stats.rx_packets++; 2841 net->stats.rx_bytes += size; 2842 muxnet_put(mux_net); 2843 return; 2844 } 2845 2846 static void gsm_mux_net_init(struct net_device *net) 2847 { 2848 static const struct net_device_ops gsm_netdev_ops = { 2849 .ndo_open = gsm_mux_net_open, 2850 .ndo_stop = gsm_mux_net_close, 2851 .ndo_start_xmit = gsm_mux_net_start_xmit, 2852 .ndo_tx_timeout = gsm_mux_net_tx_timeout, 2853 }; 2854 2855 net->netdev_ops = &gsm_netdev_ops; 2856 2857 /* fill in the other fields */ 2858 net->watchdog_timeo = GSM_NET_TX_TIMEOUT; 2859 net->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST; 2860 net->type = ARPHRD_NONE; 2861 net->tx_queue_len = 10; 2862 } 2863 2864 2865 /* caller holds the dlci mutex */ 2866 static void gsm_destroy_network(struct gsm_dlci *dlci) 2867 { 2868 struct gsm_mux_net *mux_net; 2869 2870 pr_debug("destroy network interface\n"); 2871 if (!dlci->net) 2872 return; 2873 mux_net = netdev_priv(dlci->net); 2874 muxnet_put(mux_net); 2875 } 2876 2877 2878 /* caller holds the dlci mutex */ 2879 static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc) 2880 { 2881 char *netname; 2882 int retval = 0; 2883 struct net_device *net; 2884 struct gsm_mux_net *mux_net; 2885 2886 if (!capable(CAP_NET_ADMIN)) 2887 return -EPERM; 2888 2889 /* Already in a non tty mode */ 2890 if (dlci->adaption > 2) 2891 return -EBUSY; 2892 2893 if (nc->protocol != htons(ETH_P_IP)) 2894 return -EPROTONOSUPPORT; 2895 2896 if (nc->adaption != 3 && nc->adaption != 4) 2897 return -EPROTONOSUPPORT; 2898 2899 pr_debug("create network interface\n"); 2900 2901 netname = "gsm%d"; 2902 if (nc->if_name[0] != '\0') 2903 netname = nc->if_name; 2904 net = alloc_netdev(sizeof(struct gsm_mux_net), netname, 2905 NET_NAME_UNKNOWN, gsm_mux_net_init); 2906 if (!net) { 2907 pr_err("alloc_netdev failed\n"); 2908 return -ENOMEM; 2909 } 2910 net->mtu = dlci->gsm->mtu; 2911 net->min_mtu = 8; 2912 net->max_mtu = dlci->gsm->mtu; 2913 mux_net = netdev_priv(net); 2914 mux_net->dlci = dlci; 2915 kref_init(&mux_net->ref); 2916 strncpy(nc->if_name, net->name, IFNAMSIZ); /* return net name */ 2917 2918 /* reconfigure dlci for network */ 2919 dlci->prev_adaption = dlci->adaption; 2920 dlci->prev_data = dlci->data; 2921 dlci->adaption = nc->adaption; 2922 dlci->data = gsm_mux_rx_netchar; 2923 dlci->net = net; 2924 2925 pr_debug("register netdev\n"); 2926 retval = register_netdev(net); 2927 if (retval) { 2928 pr_err("network register fail %d\n", retval); 2929 dlci_net_free(dlci); 2930 return retval; 2931 } 2932 return net->ifindex; /* return network index */ 2933 } 2934 2935 /* Line discipline for real tty */ 2936 static struct tty_ldisc_ops tty_ldisc_packet = { 2937 .owner = THIS_MODULE, 2938 .num = N_GSM0710, 2939 .name = "n_gsm", 2940 .open = gsmld_open, 2941 .close = gsmld_close, 2942 .flush_buffer = gsmld_flush_buffer, 2943 .read = gsmld_read, 2944 .write = gsmld_write, 2945 .ioctl = gsmld_ioctl, 2946 .poll = gsmld_poll, 2947 .receive_buf = gsmld_receive_buf, 2948 .write_wakeup = gsmld_write_wakeup 2949 }; 2950 2951 /* 2952 * Virtual tty side 2953 */ 2954 2955 #define TX_SIZE 512 2956 2957 static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk) 2958 { 2959 u8 modembits[5]; 2960 struct gsm_control *ctrl; 2961 int len = 2; 2962 2963 if (brk) 2964 len++; 2965 2966 modembits[0] = len << 1 | EA; /* Data bytes */ 2967 modembits[1] = dlci->addr << 2 | 3; /* DLCI, EA, 1 */ 2968 modembits[2] = gsm_encode_modem(dlci) << 1 | EA; 2969 if (brk) 2970 modembits[3] = brk << 4 | 2 | EA; /* Valid, EA */ 2971 ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len + 1); 2972 if (ctrl == NULL) 2973 return -ENOMEM; 2974 return gsm_control_wait(dlci->gsm, ctrl); 2975 } 2976 2977 static int gsm_carrier_raised(struct tty_port *port) 2978 { 2979 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port); 2980 struct gsm_mux *gsm = dlci->gsm; 2981 2982 /* Not yet open so no carrier info */ 2983 if (dlci->state != DLCI_OPEN) 2984 return 0; 2985 if (debug & 2) 2986 return 1; 2987 2988 /* 2989 * Basic mode with control channel in ADM mode may not respond 2990 * to CMD_MSC at all and modem_rx is empty. 2991 */ 2992 if (gsm->encoding == 0 && gsm->dlci[0]->mode == DLCI_MODE_ADM && 2993 !dlci->modem_rx) 2994 return 1; 2995 2996 return dlci->modem_rx & TIOCM_CD; 2997 } 2998 2999 static void gsm_dtr_rts(struct tty_port *port, int onoff) 3000 { 3001 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port); 3002 unsigned int modem_tx = dlci->modem_tx; 3003 if (onoff) 3004 modem_tx |= TIOCM_DTR | TIOCM_RTS; 3005 else 3006 modem_tx &= ~(TIOCM_DTR | TIOCM_RTS); 3007 if (modem_tx != dlci->modem_tx) { 3008 dlci->modem_tx = modem_tx; 3009 gsmtty_modem_update(dlci, 0); 3010 } 3011 } 3012 3013 static const struct tty_port_operations gsm_port_ops = { 3014 .carrier_raised = gsm_carrier_raised, 3015 .dtr_rts = gsm_dtr_rts, 3016 .destruct = gsm_dlci_free, 3017 }; 3018 3019 static int gsmtty_install(struct tty_driver *driver, struct tty_struct *tty) 3020 { 3021 struct gsm_mux *gsm; 3022 struct gsm_dlci *dlci; 3023 unsigned int line = tty->index; 3024 unsigned int mux = mux_line_to_num(line); 3025 bool alloc = false; 3026 int ret; 3027 3028 line = line & 0x3F; 3029 3030 if (mux >= MAX_MUX) 3031 return -ENXIO; 3032 /* FIXME: we need to lock gsm_mux for lifetimes of ttys eventually */ 3033 if (gsm_mux[mux] == NULL) 3034 return -EUNATCH; 3035 if (line == 0 || line > 61) /* 62/63 reserved */ 3036 return -ECHRNG; 3037 gsm = gsm_mux[mux]; 3038 if (gsm->dead) 3039 return -EL2HLT; 3040 /* If DLCI 0 is not yet fully open return an error. 3041 This is ok from a locking 3042 perspective as we don't have to worry about this 3043 if DLCI0 is lost */ 3044 mutex_lock(&gsm->mutex); 3045 if (gsm->dlci[0] && gsm->dlci[0]->state != DLCI_OPEN) { 3046 mutex_unlock(&gsm->mutex); 3047 return -EL2NSYNC; 3048 } 3049 dlci = gsm->dlci[line]; 3050 if (dlci == NULL) { 3051 alloc = true; 3052 dlci = gsm_dlci_alloc(gsm, line); 3053 } 3054 if (dlci == NULL) { 3055 mutex_unlock(&gsm->mutex); 3056 return -ENOMEM; 3057 } 3058 ret = tty_port_install(&dlci->port, driver, tty); 3059 if (ret) { 3060 if (alloc) 3061 dlci_put(dlci); 3062 mutex_unlock(&gsm->mutex); 3063 return ret; 3064 } 3065 3066 dlci_get(dlci); 3067 dlci_get(gsm->dlci[0]); 3068 mux_get(gsm); 3069 tty->driver_data = dlci; 3070 mutex_unlock(&gsm->mutex); 3071 3072 return 0; 3073 } 3074 3075 static int gsmtty_open(struct tty_struct *tty, struct file *filp) 3076 { 3077 struct gsm_dlci *dlci = tty->driver_data; 3078 struct tty_port *port = &dlci->port; 3079 struct gsm_mux *gsm = dlci->gsm; 3080 3081 port->count++; 3082 tty_port_tty_set(port, tty); 3083 3084 dlci->modem_rx = 0; 3085 /* We could in theory open and close before we wait - eg if we get 3086 a DM straight back. This is ok as that will have caused a hangup */ 3087 tty_port_set_initialized(port, 1); 3088 /* Start sending off SABM messages */ 3089 if (gsm->initiator) 3090 gsm_dlci_begin_open(dlci); 3091 /* And wait for virtual carrier */ 3092 return tty_port_block_til_ready(port, tty, filp); 3093 } 3094 3095 static void gsmtty_close(struct tty_struct *tty, struct file *filp) 3096 { 3097 struct gsm_dlci *dlci = tty->driver_data; 3098 3099 if (dlci == NULL) 3100 return; 3101 if (dlci->state == DLCI_CLOSED) 3102 return; 3103 mutex_lock(&dlci->mutex); 3104 gsm_destroy_network(dlci); 3105 mutex_unlock(&dlci->mutex); 3106 if (tty_port_close_start(&dlci->port, tty, filp) == 0) 3107 return; 3108 gsm_dlci_begin_close(dlci); 3109 if (tty_port_initialized(&dlci->port) && C_HUPCL(tty)) 3110 tty_port_lower_dtr_rts(&dlci->port); 3111 tty_port_close_end(&dlci->port, tty); 3112 tty_port_tty_set(&dlci->port, NULL); 3113 return; 3114 } 3115 3116 static void gsmtty_hangup(struct tty_struct *tty) 3117 { 3118 struct gsm_dlci *dlci = tty->driver_data; 3119 if (dlci->state == DLCI_CLOSED) 3120 return; 3121 tty_port_hangup(&dlci->port); 3122 gsm_dlci_begin_close(dlci); 3123 } 3124 3125 static int gsmtty_write(struct tty_struct *tty, const unsigned char *buf, 3126 int len) 3127 { 3128 int sent; 3129 struct gsm_dlci *dlci = tty->driver_data; 3130 if (dlci->state == DLCI_CLOSED) 3131 return -EINVAL; 3132 /* Stuff the bytes into the fifo queue */ 3133 sent = kfifo_in_locked(&dlci->fifo, buf, len, &dlci->lock); 3134 /* Need to kick the channel */ 3135 gsm_dlci_data_kick(dlci); 3136 return sent; 3137 } 3138 3139 static unsigned int gsmtty_write_room(struct tty_struct *tty) 3140 { 3141 struct gsm_dlci *dlci = tty->driver_data; 3142 if (dlci->state == DLCI_CLOSED) 3143 return 0; 3144 return TX_SIZE - kfifo_len(&dlci->fifo); 3145 } 3146 3147 static unsigned int gsmtty_chars_in_buffer(struct tty_struct *tty) 3148 { 3149 struct gsm_dlci *dlci = tty->driver_data; 3150 if (dlci->state == DLCI_CLOSED) 3151 return 0; 3152 return kfifo_len(&dlci->fifo); 3153 } 3154 3155 static void gsmtty_flush_buffer(struct tty_struct *tty) 3156 { 3157 struct gsm_dlci *dlci = tty->driver_data; 3158 if (dlci->state == DLCI_CLOSED) 3159 return; 3160 /* Caution needed: If we implement reliable transport classes 3161 then the data being transmitted can't simply be junked once 3162 it has first hit the stack. Until then we can just blow it 3163 away */ 3164 kfifo_reset(&dlci->fifo); 3165 /* Need to unhook this DLCI from the transmit queue logic */ 3166 } 3167 3168 static void gsmtty_wait_until_sent(struct tty_struct *tty, int timeout) 3169 { 3170 /* The FIFO handles the queue so the kernel will do the right 3171 thing waiting on chars_in_buffer before calling us. No work 3172 to do here */ 3173 } 3174 3175 static int gsmtty_tiocmget(struct tty_struct *tty) 3176 { 3177 struct gsm_dlci *dlci = tty->driver_data; 3178 if (dlci->state == DLCI_CLOSED) 3179 return -EINVAL; 3180 return dlci->modem_rx; 3181 } 3182 3183 static int gsmtty_tiocmset(struct tty_struct *tty, 3184 unsigned int set, unsigned int clear) 3185 { 3186 struct gsm_dlci *dlci = tty->driver_data; 3187 unsigned int modem_tx = dlci->modem_tx; 3188 3189 if (dlci->state == DLCI_CLOSED) 3190 return -EINVAL; 3191 modem_tx &= ~clear; 3192 modem_tx |= set; 3193 3194 if (modem_tx != dlci->modem_tx) { 3195 dlci->modem_tx = modem_tx; 3196 return gsmtty_modem_update(dlci, 0); 3197 } 3198 return 0; 3199 } 3200 3201 3202 static int gsmtty_ioctl(struct tty_struct *tty, 3203 unsigned int cmd, unsigned long arg) 3204 { 3205 struct gsm_dlci *dlci = tty->driver_data; 3206 struct gsm_netconfig nc; 3207 int index; 3208 3209 if (dlci->state == DLCI_CLOSED) 3210 return -EINVAL; 3211 switch (cmd) { 3212 case GSMIOC_ENABLE_NET: 3213 if (copy_from_user(&nc, (void __user *)arg, sizeof(nc))) 3214 return -EFAULT; 3215 nc.if_name[IFNAMSIZ-1] = '\0'; 3216 /* return net interface index or error code */ 3217 mutex_lock(&dlci->mutex); 3218 index = gsm_create_network(dlci, &nc); 3219 mutex_unlock(&dlci->mutex); 3220 if (copy_to_user((void __user *)arg, &nc, sizeof(nc))) 3221 return -EFAULT; 3222 return index; 3223 case GSMIOC_DISABLE_NET: 3224 if (!capable(CAP_NET_ADMIN)) 3225 return -EPERM; 3226 mutex_lock(&dlci->mutex); 3227 gsm_destroy_network(dlci); 3228 mutex_unlock(&dlci->mutex); 3229 return 0; 3230 default: 3231 return -ENOIOCTLCMD; 3232 } 3233 } 3234 3235 static void gsmtty_set_termios(struct tty_struct *tty, struct ktermios *old) 3236 { 3237 struct gsm_dlci *dlci = tty->driver_data; 3238 if (dlci->state == DLCI_CLOSED) 3239 return; 3240 /* For the moment its fixed. In actual fact the speed information 3241 for the virtual channel can be propogated in both directions by 3242 the RPN control message. This however rapidly gets nasty as we 3243 then have to remap modem signals each way according to whether 3244 our virtual cable is null modem etc .. */ 3245 tty_termios_copy_hw(&tty->termios, old); 3246 } 3247 3248 static void gsmtty_throttle(struct tty_struct *tty) 3249 { 3250 struct gsm_dlci *dlci = tty->driver_data; 3251 if (dlci->state == DLCI_CLOSED) 3252 return; 3253 if (C_CRTSCTS(tty)) 3254 dlci->modem_tx &= ~TIOCM_RTS; 3255 dlci->throttled = true; 3256 /* Send an MSC with RTS cleared */ 3257 gsmtty_modem_update(dlci, 0); 3258 } 3259 3260 static void gsmtty_unthrottle(struct tty_struct *tty) 3261 { 3262 struct gsm_dlci *dlci = tty->driver_data; 3263 if (dlci->state == DLCI_CLOSED) 3264 return; 3265 if (C_CRTSCTS(tty)) 3266 dlci->modem_tx |= TIOCM_RTS; 3267 dlci->throttled = false; 3268 /* Send an MSC with RTS set */ 3269 gsmtty_modem_update(dlci, 0); 3270 } 3271 3272 static int gsmtty_break_ctl(struct tty_struct *tty, int state) 3273 { 3274 struct gsm_dlci *dlci = tty->driver_data; 3275 int encode = 0; /* Off */ 3276 if (dlci->state == DLCI_CLOSED) 3277 return -EINVAL; 3278 3279 if (state == -1) /* "On indefinitely" - we can't encode this 3280 properly */ 3281 encode = 0x0F; 3282 else if (state > 0) { 3283 encode = state / 200; /* mS to encoding */ 3284 if (encode > 0x0F) 3285 encode = 0x0F; /* Best effort */ 3286 } 3287 return gsmtty_modem_update(dlci, encode); 3288 } 3289 3290 static void gsmtty_cleanup(struct tty_struct *tty) 3291 { 3292 struct gsm_dlci *dlci = tty->driver_data; 3293 struct gsm_mux *gsm = dlci->gsm; 3294 3295 dlci_put(dlci); 3296 dlci_put(gsm->dlci[0]); 3297 mux_put(gsm); 3298 } 3299 3300 /* Virtual ttys for the demux */ 3301 static const struct tty_operations gsmtty_ops = { 3302 .install = gsmtty_install, 3303 .open = gsmtty_open, 3304 .close = gsmtty_close, 3305 .write = gsmtty_write, 3306 .write_room = gsmtty_write_room, 3307 .chars_in_buffer = gsmtty_chars_in_buffer, 3308 .flush_buffer = gsmtty_flush_buffer, 3309 .ioctl = gsmtty_ioctl, 3310 .throttle = gsmtty_throttle, 3311 .unthrottle = gsmtty_unthrottle, 3312 .set_termios = gsmtty_set_termios, 3313 .hangup = gsmtty_hangup, 3314 .wait_until_sent = gsmtty_wait_until_sent, 3315 .tiocmget = gsmtty_tiocmget, 3316 .tiocmset = gsmtty_tiocmset, 3317 .break_ctl = gsmtty_break_ctl, 3318 .cleanup = gsmtty_cleanup, 3319 }; 3320 3321 3322 3323 static int __init gsm_init(void) 3324 { 3325 /* Fill in our line protocol discipline, and register it */ 3326 int status = tty_register_ldisc(&tty_ldisc_packet); 3327 if (status != 0) { 3328 pr_err("n_gsm: can't register line discipline (err = %d)\n", 3329 status); 3330 return status; 3331 } 3332 3333 gsm_tty_driver = tty_alloc_driver(256, TTY_DRIVER_REAL_RAW | 3334 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_HARDWARE_BREAK); 3335 if (IS_ERR(gsm_tty_driver)) { 3336 pr_err("gsm_init: tty allocation failed.\n"); 3337 status = PTR_ERR(gsm_tty_driver); 3338 goto err_unreg_ldisc; 3339 } 3340 gsm_tty_driver->driver_name = "gsmtty"; 3341 gsm_tty_driver->name = "gsmtty"; 3342 gsm_tty_driver->major = 0; /* Dynamic */ 3343 gsm_tty_driver->minor_start = 0; 3344 gsm_tty_driver->type = TTY_DRIVER_TYPE_SERIAL; 3345 gsm_tty_driver->subtype = SERIAL_TYPE_NORMAL; 3346 gsm_tty_driver->init_termios = tty_std_termios; 3347 /* Fixme */ 3348 gsm_tty_driver->init_termios.c_lflag &= ~ECHO; 3349 tty_set_operations(gsm_tty_driver, &gsmtty_ops); 3350 3351 if (tty_register_driver(gsm_tty_driver)) { 3352 pr_err("gsm_init: tty registration failed.\n"); 3353 status = -EBUSY; 3354 goto err_put_driver; 3355 } 3356 pr_debug("gsm_init: loaded as %d,%d.\n", 3357 gsm_tty_driver->major, gsm_tty_driver->minor_start); 3358 return 0; 3359 err_put_driver: 3360 tty_driver_kref_put(gsm_tty_driver); 3361 err_unreg_ldisc: 3362 tty_unregister_ldisc(&tty_ldisc_packet); 3363 return status; 3364 } 3365 3366 static void __exit gsm_exit(void) 3367 { 3368 tty_unregister_ldisc(&tty_ldisc_packet); 3369 tty_unregister_driver(gsm_tty_driver); 3370 tty_driver_kref_put(gsm_tty_driver); 3371 } 3372 3373 module_init(gsm_init); 3374 module_exit(gsm_exit); 3375 3376 3377 MODULE_LICENSE("GPL"); 3378 MODULE_ALIAS_LDISC(N_GSM0710); 3379