drivers/tty/serial/jsm/jsm_tty.c

   1 /************************************************************************
   2  * Copyright 2003 Digi International (www.digi.com)
   3  *
   4  * Copyright (C) 2004 IBM Corporation. All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2, or (at your option)
   9  * any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED; without even the
  13  * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
  14  * PURPOSE.  See the GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 * Temple Place - Suite 330, Boston,
  19  * MA  02111-1307, USA.
  20  *
  21  * Contact Information:
  22  * Scott H Kilau <Scott_Kilau@digi.com>
  23  * Ananda Venkatarman <mansarov@us.ibm.com>
  24  * Modifications:
  25  * 01/19/06:    changed jsm_input routine to use the dynamically allocated
  26  *              tty_buffer changes. Contributors: Scott Kilau and Ananda V.
  27  ***********************************************************************/
  28 #include <linux/tty.h>
  29 #include <linux/tty_flip.h>
  30 #include <linux/serial_reg.h>
  31 #include <linux/delay.h>        /* For udelay */
  32 #include <linux/pci.h>
  33 #include <linux/slab.h>
  34
  35 #include "jsm.h"
  36
  37 static DECLARE_BITMAP(linemap, MAXLINES);
  38
  39 static void jsm_carrier(struct jsm_channel *ch);
  40
  41 static inline int jsm_get_mstat(struct jsm_channel *ch)
  42 {
  43         unsigned char mstat;
  44         unsigned result;
  45
  46         jsm_dbg(IOCTL, &ch->ch_bd->pci_dev, "start\n");
  47
  48         mstat = (ch->ch_mostat | ch->ch_mistat);
  49
  50         result = 0;
  51
  52         if (mstat & UART_MCR_DTR)
  53                 result |= TIOCM_DTR;
  54         if (mstat & UART_MCR_RTS)
  55                 result |= TIOCM_RTS;
  56         if (mstat & UART_MSR_CTS)
  57                 result |= TIOCM_CTS;
  58         if (mstat & UART_MSR_DSR)
  59                 result |= TIOCM_DSR;
  60         if (mstat & UART_MSR_RI)
  61                 result |= TIOCM_RI;
  62         if (mstat & UART_MSR_DCD)
  63                 result |= TIOCM_CD;
  64
  65         jsm_dbg(IOCTL, &ch->ch_bd->pci_dev, "finish\n");
  66         return result;
  67 }
  68
  69 static unsigned int jsm_tty_tx_empty(struct uart_port *port)
  70 {
  71         return TIOCSER_TEMT;
  72 }
  73
  74 /*
  75  * Return modem signals to ld.
  76  */
  77 static unsigned int jsm_tty_get_mctrl(struct uart_port *port)
  78 {
  79         int result;
  80         struct jsm_channel *channel = (struct jsm_channel *)port;
  81
  82         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "start\n");
  83
  84         result = jsm_get_mstat(channel);
  85
  86         if (result < 0)
  87                 return -ENXIO;
  88
  89         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "finish\n");
  90
  91         return result;
  92 }
  93
  94 /*
  95  * jsm_set_modem_info()
  96  *
  97  * Set modem signals, called by ld.
  98  */
  99 static void jsm_tty_set_mctrl(struct uart_port *port, unsigned int mctrl)
 100 {
 101         struct jsm_channel *channel = (struct jsm_channel *)port;
 102
 103         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "start\n");
 104
 105         if (mctrl & TIOCM_RTS)
 106                 channel->ch_mostat |= UART_MCR_RTS;
 107         else
 108                 channel->ch_mostat &= ~UART_MCR_RTS;
 109
 110         if (mctrl & TIOCM_DTR)
 111                 channel->ch_mostat |= UART_MCR_DTR;
 112         else
 113                 channel->ch_mostat &= ~UART_MCR_DTR;
 114
 115         channel->ch_bd->bd_ops->assert_modem_signals(channel);
 116
 117         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "finish\n");
 118         udelay(10);
 119 }
 120
 121 /*
 122  * jsm_tty_write()
 123  *
 124  * Take data from the user or kernel and send it out to the FEP.
 125  * In here exists all the Transparent Print magic as well.
 126  */
 127 static void jsm_tty_write(struct uart_port *port)
 128 {
 129         struct jsm_channel *channel;
 130         channel = container_of(port, struct jsm_channel, uart_port);
 131         channel->ch_bd->bd_ops->copy_data_from_queue_to_uart(channel);
 132 }
 133
 134 static void jsm_tty_start_tx(struct uart_port *port)
 135 {
 136         struct jsm_channel *channel = (struct jsm_channel *)port;
 137
 138         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "start\n");
 139
 140         channel->ch_flags &= ~(CH_STOP);
 141         jsm_tty_write(port);
 142
 143         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "finish\n");
 144 }
 145
 146 static void jsm_tty_stop_tx(struct uart_port *port)
 147 {
 148         struct jsm_channel *channel = (struct jsm_channel *)port;
 149
 150         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "start\n");
 151
 152         channel->ch_flags |= (CH_STOP);
 153
 154         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "finish\n");
 155 }
 156
 157 static void jsm_tty_send_xchar(struct uart_port *port, char ch)
 158 {
 159         unsigned long lock_flags;
 160         struct jsm_channel *channel = (struct jsm_channel *)port;
 161         struct ktermios *termios;
 162
 163         spin_lock_irqsave(&port->lock, lock_flags);
 164         termios = &port->state->port.tty->termios;
 165         if (ch == termios->c_cc[VSTART])
 166                 channel->ch_bd->bd_ops->send_start_character(channel);
 167
 168         if (ch == termios->c_cc[VSTOP])
 169                 channel->ch_bd->bd_ops->send_stop_character(channel);
 170         spin_unlock_irqrestore(&port->lock, lock_flags);
 171 }
 172
 173 static void jsm_tty_stop_rx(struct uart_port *port)
 174 {
 175         struct jsm_channel *channel = (struct jsm_channel *)port;
 176
 177         channel->ch_bd->bd_ops->disable_receiver(channel);
 178 }
 179
 180 static void jsm_tty_enable_ms(struct uart_port *port)
 181 {
 182         /* Nothing needed */
 183 }
 184
 185 static void jsm_tty_break(struct uart_port *port, int break_state)
 186 {
 187         unsigned long lock_flags;
 188         struct jsm_channel *channel = (struct jsm_channel *)port;
 189
 190         spin_lock_irqsave(&port->lock, lock_flags);
 191         if (break_state == -1)
 192                 channel->ch_bd->bd_ops->send_break(channel);
 193         else
 194                 channel->ch_bd->bd_ops->clear_break(channel, 0);
 195
 196         spin_unlock_irqrestore(&port->lock, lock_flags);
 197 }
 198
 199 static int jsm_tty_open(struct uart_port *port)
 200 {
 201         struct jsm_board *brd;
 202         struct jsm_channel *channel = (struct jsm_channel *)port;
 203         struct ktermios *termios;
 204
 205         /* Get board pointer from our array of majors we have allocated */
 206         brd = channel->ch_bd;
 207
 208         /*
 209          * Allocate channel buffers for read/write/error.
 210          * Set flag, so we don't get trounced on.
 211          */
 212         channel->ch_flags |= (CH_OPENING);
 213
 214         /* Drop locks, as malloc with GFP_KERNEL can sleep */
 215
 216         if (!channel->ch_rqueue) {
 217                 channel->ch_rqueue = kzalloc(RQUEUESIZE, GFP_KERNEL);
 218                 if (!channel->ch_rqueue) {
 219                         jsm_dbg(INIT, &channel->ch_bd->pci_dev,
 220                                 "unable to allocate read queue buf\n");
 221                         return -ENOMEM;
 222                 }
 223         }
 224         if (!channel->ch_equeue) {
 225                 channel->ch_equeue = kzalloc(EQUEUESIZE, GFP_KERNEL);
 226                 if (!channel->ch_equeue) {
 227                         jsm_dbg(INIT, &channel->ch_bd->pci_dev,
 228                                 "unable to allocate error queue buf\n");
 229                         return -ENOMEM;
 230                 }
 231         }
 232
 233         channel->ch_flags &= ~(CH_OPENING);
 234         /*
 235          * Initialize if neither terminal is open.
 236          */
 237         jsm_dbg(OPEN, &channel->ch_bd->pci_dev,
 238                 "jsm_open: initializing channel in open...\n");
 239
 240         /*
 241          * Flush input queues.
 242          */
 243         channel->ch_r_head = channel->ch_r_tail = 0;
 244         channel->ch_e_head = channel->ch_e_tail = 0;
 245
 246         brd->bd_ops->flush_uart_write(channel);
 247         brd->bd_ops->flush_uart_read(channel);
 248
 249         channel->ch_flags = 0;
 250         channel->ch_cached_lsr = 0;
 251         channel->ch_stops_sent = 0;
 252
 253         termios = &port->state->port.tty->termios;
 254         channel->ch_c_cflag     = termios->c_cflag;
 255         channel->ch_c_iflag     = termios->c_iflag;
 256         channel->ch_c_oflag     = termios->c_oflag;
 257         channel->ch_c_lflag     = termios->c_lflag;
 258         channel->ch_startc      = termios->c_cc[VSTART];
 259         channel->ch_stopc       = termios->c_cc[VSTOP];
 260
 261         /* Tell UART to init itself */
 262         brd->bd_ops->uart_init(channel);
 263
 264         /*
 265          * Run param in case we changed anything
 266          */
 267         brd->bd_ops->param(channel);
 268
 269         jsm_carrier(channel);
 270
 271         channel->ch_open_count++;
 272
 273         jsm_dbg(OPEN, &channel->ch_bd->pci_dev, "finish\n");
 274         return 0;
 275 }
 276
 277 static void jsm_tty_close(struct uart_port *port)
 278 {
 279         struct jsm_board *bd;
 280         struct ktermios *ts;
 281         struct jsm_channel *channel = (struct jsm_channel *)port;
 282
 283         jsm_dbg(CLOSE, &channel->ch_bd->pci_dev, "start\n");
 284
 285         bd = channel->ch_bd;
 286         ts = &port->state->port.tty->termios;
 287
 288         channel->ch_flags &= ~(CH_STOPI);
 289
 290         channel->ch_open_count--;
 291
 292         /*
 293          * If we have HUPCL set, lower DTR and RTS
 294          */
 295         if (channel->ch_c_cflag & HUPCL) {
 296                 jsm_dbg(CLOSE, &channel->ch_bd->pci_dev,
 297                         "Close. HUPCL set, dropping DTR/RTS\n");
 298
 299                 /* Drop RTS/DTR */
 300                 channel->ch_mostat &= ~(UART_MCR_DTR | UART_MCR_RTS);
 301                 bd->bd_ops->assert_modem_signals(channel);
 302         }
 303
 304         /* Turn off UART interrupts for this port */
 305         channel->ch_bd->bd_ops->uart_off(channel);
 306
 307         jsm_dbg(CLOSE, &channel->ch_bd->pci_dev, "finish\n");
 308 }
 309
 310 static void jsm_tty_set_termios(struct uart_port *port,
 311                                  struct ktermios *termios,
 312                                  struct ktermios *old_termios)
 313 {
 314         unsigned long lock_flags;
 315         struct jsm_channel *channel = (struct jsm_channel *)port;
 316
 317         spin_lock_irqsave(&port->lock, lock_flags);
 318         channel->ch_c_cflag     = termios->c_cflag;
 319         channel->ch_c_iflag     = termios->c_iflag;
 320         channel->ch_c_oflag     = termios->c_oflag;
 321         channel->ch_c_lflag     = termios->c_lflag;
 322         channel->ch_startc      = termios->c_cc[VSTART];
 323         channel->ch_stopc       = termios->c_cc[VSTOP];
 324
 325         channel->ch_bd->bd_ops->param(channel);
 326         jsm_carrier(channel);
 327         spin_unlock_irqrestore(&port->lock, lock_flags);
 328 }
 329
 330 static const char *jsm_tty_type(struct uart_port *port)
 331 {
 332         return "jsm";
 333 }
 334
 335 static void jsm_tty_release_port(struct uart_port *port)
 336 {
 337 }
 338
 339 static int jsm_tty_request_port(struct uart_port *port)
 340 {
 341         return 0;
 342 }
 343
 344 static void jsm_config_port(struct uart_port *port, int flags)
 345 {
 346         port->type = PORT_JSM;
 347 }
 348
 349 static struct uart_ops jsm_ops = {
 350         .tx_empty       = jsm_tty_tx_empty,
 351         .set_mctrl      = jsm_tty_set_mctrl,
 352         .get_mctrl      = jsm_tty_get_mctrl,
 353         .stop_tx        = jsm_tty_stop_tx,
 354         .start_tx       = jsm_tty_start_tx,
 355         .send_xchar     = jsm_tty_send_xchar,
 356         .stop_rx        = jsm_tty_stop_rx,
 357         .enable_ms      = jsm_tty_enable_ms,
 358         .break_ctl      = jsm_tty_break,
 359         .startup        = jsm_tty_open,
 360         .shutdown       = jsm_tty_close,
 361         .set_termios    = jsm_tty_set_termios,
 362         .type           = jsm_tty_type,
 363         .release_port   = jsm_tty_release_port,
 364         .request_port   = jsm_tty_request_port,
 365         .config_port    = jsm_config_port,
 366 };
 367
 368 /*
 369  * jsm_tty_init()
 370  *
 371  * Init the tty subsystem.  Called once per board after board has been
 372  * downloaded and init'ed.
 373  */
 374 int jsm_tty_init(struct jsm_board *brd)
 375 {
 376         int i;
 377         void __iomem *vaddr;
 378         struct jsm_channel *ch;
 379
 380         if (!brd)
 381                 return -ENXIO;
 382
 383         jsm_dbg(INIT, &brd->pci_dev, "start\n");
 384
 385         /*
 386          * Initialize board structure elements.
 387          */
 388
 389         brd->nasync = brd->maxports;
 390
 391         /*
 392          * Allocate channel memory that might not have been allocated
 393          * when the driver was first loaded.
 394          */
 395         for (i = 0; i < brd->nasync; i++) {
 396                 if (!brd->channels[i]) {
 397
 398                         /*
 399                          * Okay to malloc with GFP_KERNEL, we are not at
 400                          * interrupt context, and there are no locks held.
 401                          */
 402                         brd->channels[i] = kzalloc(sizeof(struct jsm_channel), GFP_KERNEL);
 403                         if (!brd->channels[i]) {
 404                                 jsm_dbg(CORE, &brd->pci_dev,
 405                                         "%s:%d Unable to allocate memory for channel struct\n",
 406                                         __FILE__, __LINE__);
 407                         }
 408                 }
 409         }
 410
 411         ch = brd->channels[0];
 412         vaddr = brd->re_map_membase;
 413
 414         /* Set up channel variables */
 415         for (i = 0; i < brd->nasync; i++, ch = brd->channels[i]) {
 416
 417                 if (!brd->channels[i])
 418                         continue;
 419
 420                 spin_lock_init(&ch->ch_lock);
 421
 422                 if (brd->bd_uart_offset == 0x200)
 423                         ch->ch_neo_uart =  vaddr + (brd->bd_uart_offset * i);
 424
 425                 ch->ch_bd = brd;
 426                 ch->ch_portnum = i;
 427
 428                 /* .25 second delay */
 429                 ch->ch_close_delay = 250;
 430
 431                 init_waitqueue_head(&ch->ch_flags_wait);
 432         }
 433
 434         jsm_dbg(INIT, &brd->pci_dev, "finish\n");
 435         return 0;
 436 }
 437
 438 int jsm_uart_port_init(struct jsm_board *brd)
 439 {
 440         int i, rc;
 441         unsigned int line;
 442         struct jsm_channel *ch;
 443
 444         if (!brd)
 445                 return -ENXIO;
 446
 447         jsm_dbg(INIT, &brd->pci_dev, "start\n");
 448
 449         /*
 450          * Initialize board structure elements.
 451          */
 452
 453         brd->nasync = brd->maxports;
 454
 455         /* Set up channel variables */
 456         for (i = 0; i < brd->nasync; i++, ch = brd->channels[i]) {
 457
 458                 if (!brd->channels[i])
 459                         continue;
 460
 461                 brd->channels[i]->uart_port.irq = brd->irq;
 462                 brd->channels[i]->uart_port.uartclk = 14745600;
 463                 brd->channels[i]->uart_port.type = PORT_JSM;
 464                 brd->channels[i]->uart_port.iotype = UPIO_MEM;
 465                 brd->channels[i]->uart_port.membase = brd->re_map_membase;
 466                 brd->channels[i]->uart_port.fifosize = 16;
 467                 brd->channels[i]->uart_port.ops = &jsm_ops;
 468                 line = find_first_zero_bit(linemap, MAXLINES);
 469                 if (line >= MAXLINES) {
 470                         printk(KERN_INFO "jsm: linemap is full, added device failed\n");
 471                         continue;
 472                 } else
 473                         set_bit(line, linemap);
 474                 brd->channels[i]->uart_port.line = line;
 475                 rc = uart_add_one_port (&jsm_uart_driver, &brd->channels[i]->uart_port);
 476                 if (rc){
 477                         printk(KERN_INFO "jsm: Port %d failed. Aborting...\n", i);
 478                         return rc;
 479                 }
 480                 else
 481                         printk(KERN_INFO "jsm: Port %d added\n", i);
 482         }
 483
 484         jsm_dbg(INIT, &brd->pci_dev, "finish\n");
 485         return 0;
 486 }
 487
 488 int jsm_remove_uart_port(struct jsm_board *brd)
 489 {
 490         int i;
 491         struct jsm_channel *ch;
 492
 493         if (!brd)
 494                 return -ENXIO;
 495
 496         jsm_dbg(INIT, &brd->pci_dev, "start\n");
 497
 498         /*
 499          * Initialize board structure elements.
 500          */
 501
 502         brd->nasync = brd->maxports;
 503
 504         /* Set up channel variables */
 505         for (i = 0; i < brd->nasync; i++) {
 506
 507                 if (!brd->channels[i])
 508                         continue;
 509
 510                 ch = brd->channels[i];
 511
 512                 clear_bit(ch->uart_port.line, linemap);
 513                 uart_remove_one_port(&jsm_uart_driver, &brd->channels[i]->uart_port);
 514         }
 515
 516         jsm_dbg(INIT, &brd->pci_dev, "finish\n");
 517         return 0;
 518 }
 519
 520 void jsm_input(struct jsm_channel *ch)
 521 {
 522         struct jsm_board *bd;
 523         struct tty_struct *tp;
 524         u32 rmask;
 525         u16 head;
 526         u16 tail;
 527         int data_len;
 528         unsigned long lock_flags;
 529         int len = 0;
 530         int n = 0;
 531         int s = 0;
 532         int i = 0;
 533
 534         jsm_dbg(READ, &ch->ch_bd->pci_dev, "start\n");
 535
 536         if (!ch)
 537                 return;
 538
 539         tp = ch->uart_port.state->port.tty;
 540
 541         bd = ch->ch_bd;
 542         if(!bd)
 543                 return;
 544
 545         spin_lock_irqsave(&ch->ch_lock, lock_flags);
 546
 547         /*
 548          *Figure the number of characters in the buffer.
 549          *Exit immediately if none.
 550          */
 551
 552         rmask = RQUEUEMASK;
 553
 554         head = ch->ch_r_head & rmask;
 555         tail = ch->ch_r_tail & rmask;
 556
 557         data_len = (head - tail) & rmask;
 558         if (data_len == 0) {
 559                 spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
 560                 return;
 561         }
 562
 563         jsm_dbg(READ, &ch->ch_bd->pci_dev, "start\n");
 564
 565         /*
 566          *If the device is not open, or CREAD is off, flush
 567          *input data and return immediately.
 568          */
 569         if (!tp ||
 570                 !(tp->termios.c_cflag & CREAD) ) {
 571
 572                 jsm_dbg(READ, &ch->ch_bd->pci_dev,
 573                         "input. dropping %d bytes on port %d...\n",
 574                         data_len, ch->ch_portnum);
 575                 ch->ch_r_head = tail;
 576
 577                 /* Force queue flow control to be released, if needed */
 578                 jsm_check_queue_flow_control(ch);
 579
 580                 spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
 581                 return;
 582         }
 583
 584         /*
 585          * If we are throttled, simply don't read any data.
 586          */
 587         if (ch->ch_flags & CH_STOPI) {
 588                 spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
 589                 jsm_dbg(READ, &ch->ch_bd->pci_dev,
 590                         "Port %d throttled, not reading any data. head: %x tail: %x\n",
 591                         ch->ch_portnum, head, tail);
 592                 return;
 593         }
 594
 595         jsm_dbg(READ, &ch->ch_bd->pci_dev, "start 2\n");
 596
 597         if (data_len <= 0) {
 598                 spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
 599                 jsm_dbg(READ, &ch->ch_bd->pci_dev, "jsm_input 1\n");
 600                 return;
 601         }
 602
 603         len = tty_buffer_request_room(tp, data_len);
 604         n = len;
 605
 606         /*
 607          * n now contains the most amount of data we can copy,
 608          * bounded either by the flip buffer size or the amount
 609          * of data the card actually has pending...
 610          */
 611         while (n) {
 612                 s = ((head >= tail) ? head : RQUEUESIZE) - tail;
 613                 s = min(s, n);
 614
 615                 if (s <= 0)
 616                         break;
 617
 618                         /*
 619                          * If conditions are such that ld needs to see all
 620                          * UART errors, we will have to walk each character
 621                          * and error byte and send them to the buffer one at
 622                          * a time.
 623                          */
 624
 625                 if (I_PARMRK(tp) || I_BRKINT(tp) || I_INPCK(tp)) {
 626                         for (i = 0; i < s; i++) {
 627                                 /*
 628                                  * Give the Linux ld the flags in the
 629                                  * format it likes.
 630                                  */
 631                                 if (*(ch->ch_equeue +tail +i) & UART_LSR_BI)
 632                                         tty_insert_flip_char(tp, *(ch->ch_rqueue +tail +i),  TTY_BREAK);
 633                                 else if (*(ch->ch_equeue +tail +i) & UART_LSR_PE)
 634                                         tty_insert_flip_char(tp, *(ch->ch_rqueue +tail +i), TTY_PARITY);
 635                                 else if (*(ch->ch_equeue +tail +i) & UART_LSR_FE)
 636                                         tty_insert_flip_char(tp, *(ch->ch_rqueue +tail +i), TTY_FRAME);
 637                                 else
 638                                         tty_insert_flip_char(tp, *(ch->ch_rqueue +tail +i), TTY_NORMAL);
 639                         }
 640                 } else {
 641                         tty_insert_flip_string(tp, ch->ch_rqueue + tail, s) ;
 642                 }
 643                 tail += s;
 644                 n -= s;
 645                 /* Flip queue if needed */
 646                 tail &= rmask;
 647         }
 648
 649         ch->ch_r_tail = tail & rmask;
 650         ch->ch_e_tail = tail & rmask;
 651         jsm_check_queue_flow_control(ch);
 652         spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
 653
 654         /* Tell the tty layer its okay to "eat" the data now */
 655         tty_flip_buffer_push(tp);
 656
 657         jsm_dbg(IOCTL, &ch->ch_bd->pci_dev, "finish\n");
 658 }
 659
 660 static void jsm_carrier(struct jsm_channel *ch)
 661 {
 662         struct jsm_board *bd;
 663
 664         int virt_carrier = 0;
 665         int phys_carrier = 0;
 666
 667         jsm_dbg(CARR, &ch->ch_bd->pci_dev, "start\n");
 668         if (!ch)
 669                 return;
 670
 671         bd = ch->ch_bd;
 672
 673         if (!bd)
 674                 return;
 675
 676         if (ch->ch_mistat & UART_MSR_DCD) {
 677                 jsm_dbg(CARR, &ch->ch_bd->pci_dev, "mistat: %x D_CD: %x\n",
 678                         ch->ch_mistat, ch->ch_mistat & UART_MSR_DCD);
 679                 phys_carrier = 1;
 680         }
 681
 682         if (ch->ch_c_cflag & CLOCAL)
 683                 virt_carrier = 1;
 684
 685         jsm_dbg(CARR, &ch->ch_bd->pci_dev, "DCD: physical: %d virt: %d\n",
 686                 phys_carrier, virt_carrier);
 687
 688         /*
 689          * Test for a VIRTUAL carrier transition to HIGH.
 690          */
 691         if (((ch->ch_flags & CH_FCAR) == 0) && (virt_carrier == 1)) {
 692
 693                 /*
 694                  * When carrier rises, wake any threads waiting
 695                  * for carrier in the open routine.
 696                  */
 697
 698                 jsm_dbg(CARR, &ch->ch_bd->pci_dev, "carrier: virt DCD rose\n");
 699
 700                 if (waitqueue_active(&(ch->ch_flags_wait)))
 701                         wake_up_interruptible(&ch->ch_flags_wait);
 702         }
 703
 704         /*
 705          * Test for a PHYSICAL carrier transition to HIGH.
 706          */
 707         if (((ch->ch_flags & CH_CD) == 0) && (phys_carrier == 1)) {
 708
 709                 /*
 710                  * When carrier rises, wake any threads waiting
 711                  * for carrier in the open routine.
 712                  */
 713
 714                 jsm_dbg(CARR, &ch->ch_bd->pci_dev,
 715                         "carrier: physical DCD rose\n");
 716
 717                 if (waitqueue_active(&(ch->ch_flags_wait)))
 718                         wake_up_interruptible(&ch->ch_flags_wait);
 719         }
 720
 721         /*
 722          *  Test for a PHYSICAL transition to low, so long as we aren't
 723          *  currently ignoring physical transitions (which is what "virtual
 724          *  carrier" indicates).
 725          *
 726          *  The transition of the virtual carrier to low really doesn't
 727          *  matter... it really only means "ignore carrier state", not
 728          *  "make pretend that carrier is there".
 729          */
 730         if ((virt_carrier == 0) && ((ch->ch_flags & CH_CD) != 0)
 731                         && (phys_carrier == 0)) {
 732                 /*
 733                  *      When carrier drops:
 734                  *
 735                  *      Drop carrier on all open units.
 736                  *
 737                  *      Flush queues, waking up any task waiting in the
 738                  *      line discipline.
 739                  *
 740                  *      Send a hangup to the control terminal.
 741                  *
 742                  *      Enable all select calls.
 743                  */
 744                 if (waitqueue_active(&(ch->ch_flags_wait)))
 745                         wake_up_interruptible(&ch->ch_flags_wait);
 746         }
 747
 748         /*
 749          *  Make sure that our cached values reflect the current reality.
 750          */
 751         if (virt_carrier == 1)
 752                 ch->ch_flags |= CH_FCAR;
 753         else
 754                 ch->ch_flags &= ~CH_FCAR;
 755
 756         if (phys_carrier == 1)
 757                 ch->ch_flags |= CH_CD;
 758         else
 759                 ch->ch_flags &= ~CH_CD;
 760 }
 761
 762
 763 void jsm_check_queue_flow_control(struct jsm_channel *ch)
 764 {
 765         struct board_ops *bd_ops = ch->ch_bd->bd_ops;
 766         int qleft;
 767
 768         /* Store how much space we have left in the queue */
 769         if ((qleft = ch->ch_r_tail - ch->ch_r_head - 1) < 0)
 770                 qleft += RQUEUEMASK + 1;
 771
 772         /*
 773          * Check to see if we should enforce flow control on our queue because
 774          * the ld (or user) isn't reading data out of our queue fast enuf.
 775          *
 776          * NOTE: This is done based on what the current flow control of the
 777          * port is set for.
 778          *
 779          * 1) HWFLOW (RTS) - Turn off the UART's Receive interrupt.
 780          *      This will cause the UART's FIFO to back up, and force
 781          *      the RTS signal to be dropped.
 782          * 2) SWFLOW (IXOFF) - Keep trying to send a stop character to
 783          *      the other side, in hopes it will stop sending data to us.
 784          * 3) NONE - Nothing we can do.  We will simply drop any extra data
 785          *      that gets sent into us when the queue fills up.
 786          */
 787         if (qleft < 256) {
 788                 /* HWFLOW */
 789                 if (ch->ch_c_cflag & CRTSCTS) {
 790                         if(!(ch->ch_flags & CH_RECEIVER_OFF)) {
 791                                 bd_ops->disable_receiver(ch);
 792                                 ch->ch_flags |= (CH_RECEIVER_OFF);
 793                                 jsm_dbg(READ, &ch->ch_bd->pci_dev,
 794                                         "Internal queue hit hilevel mark (%d)! Turning off interrupts\n",
 795                                         qleft);
 796                         }
 797                 }
 798                 /* SWFLOW */
 799                 else if (ch->ch_c_iflag & IXOFF) {
 800                         if (ch->ch_stops_sent <= MAX_STOPS_SENT) {
 801                                 bd_ops->send_stop_character(ch);
 802                                 ch->ch_stops_sent++;
 803                                 jsm_dbg(READ, &ch->ch_bd->pci_dev,
 804                                         "Sending stop char! Times sent: %x\n",
 805                                         ch->ch_stops_sent);
 806                         }
 807                 }
 808         }
 809
 810         /*
 811          * Check to see if we should unenforce flow control because
 812          * ld (or user) finally read enuf data out of our queue.
 813          *
 814          * NOTE: This is done based on what the current flow control of the
 815          * port is set for.
 816          *
 817          * 1) HWFLOW (RTS) - Turn back on the UART's Receive interrupt.
 818          *      This will cause the UART's FIFO to raise RTS back up,
 819          *      which will allow the other side to start sending data again.
 820          * 2) SWFLOW (IXOFF) - Send a start character to
 821          *      the other side, so it will start sending data to us again.
 822          * 3) NONE - Do nothing. Since we didn't do anything to turn off the
 823          *      other side, we don't need to do anything now.
 824          */
 825         if (qleft > (RQUEUESIZE / 2)) {
 826                 /* HWFLOW */
 827                 if (ch->ch_c_cflag & CRTSCTS) {
 828                         if (ch->ch_flags & CH_RECEIVER_OFF) {
 829                                 bd_ops->enable_receiver(ch);
 830                                 ch->ch_flags &= ~(CH_RECEIVER_OFF);
 831                                 jsm_dbg(READ, &ch->ch_bd->pci_dev,
 832                                         "Internal queue hit lowlevel mark (%d)! Turning on interrupts\n",
 833                                         qleft);
 834                         }
 835                 }
 836                 /* SWFLOW */
 837                 else if (ch->ch_c_iflag & IXOFF && ch->ch_stops_sent) {
 838                         ch->ch_stops_sent = 0;
 839                         bd_ops->send_start_character(ch);
 840                         jsm_dbg(READ, &ch->ch_bd->pci_dev,
 841                                 "Sending start char!\n");
 842                 }
 843         }
 844 }