drivers/tty/serial/jsm/jsm_tty.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /************************************************************************
   3  * Copyright 2003 Digi International (www.digi.com)
   4  *
   5  * Copyright (C) 2004 IBM Corporation. All rights reserved.
   6  *
   7  * Contact Information:
   8  * Scott H Kilau <Scott_Kilau@digi.com>
   9  * Ananda Venkatarman <mansarov@us.ibm.com>
  10  * Modifications:
  11  * 01/19/06:    changed jsm_input routine to use the dynamically allocated
  12  *              tty_buffer changes. Contributors: Scott Kilau and Ananda V.
  13  ***********************************************************************/
  14 #include <linux/tty.h>
  15 #include <linux/tty_flip.h>
  16 #include <linux/serial_reg.h>
  17 #include <linux/delay.h>        /* For udelay */
  18 #include <linux/pci.h>
  19 #include <linux/slab.h>
  20
  21 #include "jsm.h"
  22
  23 static DECLARE_BITMAP(linemap, MAXLINES);
  24
  25 static void jsm_carrier(struct jsm_channel *ch);
  26
  27 static inline int jsm_get_mstat(struct jsm_channel *ch)
  28 {
  29         unsigned char mstat;
  30         int result;
  31
  32         jsm_dbg(IOCTL, &ch->ch_bd->pci_dev, "start\n");
  33
  34         mstat = (ch->ch_mostat | ch->ch_mistat);
  35
  36         result = 0;
  37
  38         if (mstat & UART_MCR_DTR)
  39                 result |= TIOCM_DTR;
  40         if (mstat & UART_MCR_RTS)
  41                 result |= TIOCM_RTS;
  42         if (mstat & UART_MSR_CTS)
  43                 result |= TIOCM_CTS;
  44         if (mstat & UART_MSR_DSR)
  45                 result |= TIOCM_DSR;
  46         if (mstat & UART_MSR_RI)
  47                 result |= TIOCM_RI;
  48         if (mstat & UART_MSR_DCD)
  49                 result |= TIOCM_CD;
  50
  51         jsm_dbg(IOCTL, &ch->ch_bd->pci_dev, "finish\n");
  52         return result;
  53 }
  54
  55 static unsigned int jsm_tty_tx_empty(struct uart_port *port)
  56 {
  57         return TIOCSER_TEMT;
  58 }
  59
  60 /*
  61  * Return modem signals to ld.
  62  */
  63 static unsigned int jsm_tty_get_mctrl(struct uart_port *port)
  64 {
  65         int result;
  66         struct jsm_channel *channel =
  67                 container_of(port, struct jsm_channel, uart_port);
  68
  69         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "start\n");
  70
  71         result = jsm_get_mstat(channel);
  72
  73         if (result < 0)
  74                 return -ENXIO;
  75
  76         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "finish\n");
  77
  78         return result;
  79 }
  80
  81 /*
  82  * jsm_set_modem_info()
  83  *
  84  * Set modem signals, called by ld.
  85  */
  86 static void jsm_tty_set_mctrl(struct uart_port *port, unsigned int mctrl)
  87 {
  88         struct jsm_channel *channel =
  89                 container_of(port, struct jsm_channel, uart_port);
  90
  91         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "start\n");
  92
  93         if (mctrl & TIOCM_RTS)
  94                 channel->ch_mostat |= UART_MCR_RTS;
  95         else
  96                 channel->ch_mostat &= ~UART_MCR_RTS;
  97
  98         if (mctrl & TIOCM_DTR)
  99                 channel->ch_mostat |= UART_MCR_DTR;
 100         else
 101                 channel->ch_mostat &= ~UART_MCR_DTR;
 102
 103         channel->ch_bd->bd_ops->assert_modem_signals(channel);
 104
 105         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "finish\n");
 106         udelay(10);
 107 }
 108
 109 /*
 110  * jsm_tty_write()
 111  *
 112  * Take data from the user or kernel and send it out to the FEP.
 113  * In here exists all the Transparent Print magic as well.
 114  */
 115 static void jsm_tty_write(struct uart_port *port)
 116 {
 117         struct jsm_channel *channel;
 118
 119         channel = container_of(port, struct jsm_channel, uart_port);
 120         channel->ch_bd->bd_ops->copy_data_from_queue_to_uart(channel);
 121 }
 122
 123 static void jsm_tty_start_tx(struct uart_port *port)
 124 {
 125         struct jsm_channel *channel =
 126                 container_of(port, struct jsm_channel, uart_port);
 127
 128         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "start\n");
 129
 130         channel->ch_flags &= ~(CH_STOP);
 131         jsm_tty_write(port);
 132
 133         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "finish\n");
 134 }
 135
 136 static void jsm_tty_stop_tx(struct uart_port *port)
 137 {
 138         struct jsm_channel *channel =
 139                 container_of(port, struct jsm_channel, uart_port);
 140
 141         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "start\n");
 142
 143         channel->ch_flags |= (CH_STOP);
 144
 145         jsm_dbg(IOCTL, &channel->ch_bd->pci_dev, "finish\n");
 146 }
 147
 148 static void jsm_tty_send_xchar(struct uart_port *port, char ch)
 149 {
 150         unsigned long lock_flags;
 151         struct jsm_channel *channel =
 152                 container_of(port, struct jsm_channel, uart_port);
 153         struct ktermios *termios;
 154
 155         spin_lock_irqsave(&port->lock, lock_flags);
 156         termios = &port->state->port.tty->termios;
 157         if (ch == termios->c_cc[VSTART])
 158                 channel->ch_bd->bd_ops->send_start_character(channel);
 159
 160         if (ch == termios->c_cc[VSTOP])
 161                 channel->ch_bd->bd_ops->send_stop_character(channel);
 162         spin_unlock_irqrestore(&port->lock, lock_flags);
 163 }
 164
 165 static void jsm_tty_stop_rx(struct uart_port *port)
 166 {
 167         struct jsm_channel *channel =
 168                 container_of(port, struct jsm_channel, uart_port);
 169
 170         channel->ch_bd->bd_ops->disable_receiver(channel);
 171 }
 172
 173 static void jsm_tty_break(struct uart_port *port, int break_state)
 174 {
 175         unsigned long lock_flags;
 176         struct jsm_channel *channel =
 177                 container_of(port, struct jsm_channel, uart_port);
 178
 179         spin_lock_irqsave(&port->lock, lock_flags);
 180         if (break_state == -1)
 181                 channel->ch_bd->bd_ops->send_break(channel);
 182         else
 183                 channel->ch_bd->bd_ops->clear_break(channel);
 184
 185         spin_unlock_irqrestore(&port->lock, lock_flags);
 186 }
 187
 188 static int jsm_tty_open(struct uart_port *port)
 189 {
 190         unsigned long lock_flags;
 191         struct jsm_board *brd;
 192         struct jsm_channel *channel =
 193                 container_of(port, struct jsm_channel, uart_port);
 194         struct ktermios *termios;
 195
 196         /* Get board pointer from our array of majors we have allocated */
 197         brd = channel->ch_bd;
 198
 199         /*
 200          * Allocate channel buffers for read/write/error.
 201          * Set flag, so we don't get trounced on.
 202          */
 203         channel->ch_flags |= (CH_OPENING);
 204
 205         /* Drop locks, as malloc with GFP_KERNEL can sleep */
 206
 207         if (!channel->ch_rqueue) {
 208                 channel->ch_rqueue = kzalloc(RQUEUESIZE, GFP_KERNEL);
 209                 if (!channel->ch_rqueue) {
 210                         jsm_dbg(INIT, &channel->ch_bd->pci_dev,
 211                                 "unable to allocate read queue buf\n");
 212                         return -ENOMEM;
 213                 }
 214         }
 215         if (!channel->ch_equeue) {
 216                 channel->ch_equeue = kzalloc(EQUEUESIZE, GFP_KERNEL);
 217                 if (!channel->ch_equeue) {
 218                         jsm_dbg(INIT, &channel->ch_bd->pci_dev,
 219                                 "unable to allocate error queue buf\n");
 220                         return -ENOMEM;
 221                 }
 222         }
 223
 224         channel->ch_flags &= ~(CH_OPENING);
 225         /*
 226          * Initialize if neither terminal is open.
 227          */
 228         jsm_dbg(OPEN, &channel->ch_bd->pci_dev,
 229                 "jsm_open: initializing channel in open...\n");
 230
 231         /*
 232          * Flush input queues.
 233          */
 234         channel->ch_r_head = channel->ch_r_tail = 0;
 235         channel->ch_e_head = channel->ch_e_tail = 0;
 236
 237         brd->bd_ops->flush_uart_write(channel);
 238         brd->bd_ops->flush_uart_read(channel);
 239
 240         channel->ch_flags = 0;
 241         channel->ch_cached_lsr = 0;
 242         channel->ch_stops_sent = 0;
 243
 244         spin_lock_irqsave(&port->lock, lock_flags);
 245         termios = &port->state->port.tty->termios;
 246         channel->ch_c_cflag     = termios->c_cflag;
 247         channel->ch_c_iflag     = termios->c_iflag;
 248         channel->ch_c_oflag     = termios->c_oflag;
 249         channel->ch_c_lflag     = termios->c_lflag;
 250         channel->ch_startc      = termios->c_cc[VSTART];
 251         channel->ch_stopc       = termios->c_cc[VSTOP];
 252
 253         /* Tell UART to init itself */
 254         brd->bd_ops->uart_init(channel);
 255
 256         /*
 257          * Run param in case we changed anything
 258          */
 259         brd->bd_ops->param(channel);
 260
 261         jsm_carrier(channel);
 262
 263         channel->ch_open_count++;
 264         spin_unlock_irqrestore(&port->lock, lock_flags);
 265
 266         jsm_dbg(OPEN, &channel->ch_bd->pci_dev, "finish\n");
 267         return 0;
 268 }
 269
 270 static void jsm_tty_close(struct uart_port *port)
 271 {
 272         struct jsm_board *bd;
 273         struct jsm_channel *channel =
 274                 container_of(port, struct jsm_channel, uart_port);
 275
 276         jsm_dbg(CLOSE, &channel->ch_bd->pci_dev, "start\n");
 277
 278         bd = channel->ch_bd;
 279
 280         channel->ch_flags &= ~(CH_STOPI);
 281
 282         channel->ch_open_count--;
 283
 284         /*
 285          * If we have HUPCL set, lower DTR and RTS
 286          */
 287         if (channel->ch_c_cflag & HUPCL) {
 288                 jsm_dbg(CLOSE, &channel->ch_bd->pci_dev,
 289                         "Close. HUPCL set, dropping DTR/RTS\n");
 290
 291                 /* Drop RTS/DTR */
 292                 channel->ch_mostat &= ~(UART_MCR_DTR | UART_MCR_RTS);
 293                 bd->bd_ops->assert_modem_signals(channel);
 294         }
 295
 296         /* Turn off UART interrupts for this port */
 297         channel->ch_bd->bd_ops->uart_off(channel);
 298
 299         jsm_dbg(CLOSE, &channel->ch_bd->pci_dev, "finish\n");
 300 }
 301
 302 static void jsm_tty_set_termios(struct uart_port *port,
 303                                  struct ktermios *termios,
 304                                  struct ktermios *old_termios)
 305 {
 306         unsigned long lock_flags;
 307         struct jsm_channel *channel =
 308                 container_of(port, struct jsm_channel, uart_port);
 309
 310         spin_lock_irqsave(&port->lock, lock_flags);
 311         channel->ch_c_cflag     = termios->c_cflag;
 312         channel->ch_c_iflag     = termios->c_iflag;
 313         channel->ch_c_oflag     = termios->c_oflag;
 314         channel->ch_c_lflag     = termios->c_lflag;
 315         channel->ch_startc      = termios->c_cc[VSTART];
 316         channel->ch_stopc       = termios->c_cc[VSTOP];
 317
 318         channel->ch_bd->bd_ops->param(channel);
 319         jsm_carrier(channel);
 320         spin_unlock_irqrestore(&port->lock, lock_flags);
 321 }
 322
 323 static const char *jsm_tty_type(struct uart_port *port)
 324 {
 325         return "jsm";
 326 }
 327
 328 static void jsm_tty_release_port(struct uart_port *port)
 329 {
 330 }
 331
 332 static int jsm_tty_request_port(struct uart_port *port)
 333 {
 334         return 0;
 335 }
 336
 337 static void jsm_config_port(struct uart_port *port, int flags)
 338 {
 339         port->type = PORT_JSM;
 340 }
 341
 342 static const struct uart_ops jsm_ops = {
 343         .tx_empty       = jsm_tty_tx_empty,
 344         .set_mctrl      = jsm_tty_set_mctrl,
 345         .get_mctrl      = jsm_tty_get_mctrl,
 346         .stop_tx        = jsm_tty_stop_tx,
 347         .start_tx       = jsm_tty_start_tx,
 348         .send_xchar     = jsm_tty_send_xchar,
 349         .stop_rx        = jsm_tty_stop_rx,
 350         .break_ctl      = jsm_tty_break,
 351         .startup        = jsm_tty_open,
 352         .shutdown       = jsm_tty_close,
 353         .set_termios    = jsm_tty_set_termios,
 354         .type           = jsm_tty_type,
 355         .release_port   = jsm_tty_release_port,
 356         .request_port   = jsm_tty_request_port,
 357         .config_port    = jsm_config_port,
 358 };
 359
 360 /*
 361  * jsm_tty_init()
 362  *
 363  * Init the tty subsystem.  Called once per board after board has been
 364  * downloaded and init'ed.
 365  */
 366 int jsm_tty_init(struct jsm_board *brd)
 367 {
 368         int i;
 369         void __iomem *vaddr;
 370         struct jsm_channel *ch;
 371
 372         if (!brd)
 373                 return -ENXIO;
 374
 375         jsm_dbg(INIT, &brd->pci_dev, "start\n");
 376
 377         /*
 378          * Initialize board structure elements.
 379          */
 380
 381         brd->nasync = brd->maxports;
 382
 383         /*
 384          * Allocate channel memory that might not have been allocated
 385          * when the driver was first loaded.
 386          */
 387         for (i = 0; i < brd->nasync; i++) {
 388                 if (!brd->channels[i]) {
 389
 390                         /*
 391                          * Okay to malloc with GFP_KERNEL, we are not at
 392                          * interrupt context, and there are no locks held.
 393                          */
 394                         brd->channels[i] = kzalloc(sizeof(struct jsm_channel), GFP_KERNEL);
 395                         if (!brd->channels[i]) {
 396                                 jsm_dbg(CORE, &brd->pci_dev,
 397                                         "%s:%d Unable to allocate memory for channel struct\n",
 398                                         __FILE__, __LINE__);
 399                         }
 400                 }
 401         }
 402
 403         ch = brd->channels[0];
 404         vaddr = brd->re_map_membase;
 405
 406         /* Set up channel variables */
 407         for (i = 0; i < brd->nasync; i++, ch = brd->channels[i]) {
 408
 409                 if (!brd->channels[i])
 410                         continue;
 411
 412                 spin_lock_init(&ch->ch_lock);
 413
 414                 if (brd->bd_uart_offset == 0x200)
 415                         ch->ch_neo_uart =  vaddr + (brd->bd_uart_offset * i);
 416                 else
 417                         ch->ch_cls_uart =  vaddr + (brd->bd_uart_offset * i);
 418
 419                 ch->ch_bd = brd;
 420                 ch->ch_portnum = i;
 421
 422                 /* .25 second delay */
 423                 ch->ch_close_delay = 250;
 424
 425                 init_waitqueue_head(&ch->ch_flags_wait);
 426         }
 427
 428         jsm_dbg(INIT, &brd->pci_dev, "finish\n");
 429         return 0;
 430 }
 431
 432 int jsm_uart_port_init(struct jsm_board *brd)
 433 {
 434         int i, rc;
 435         unsigned int line;
 436
 437         if (!brd)
 438                 return -ENXIO;
 439
 440         jsm_dbg(INIT, &brd->pci_dev, "start\n");
 441
 442         /*
 443          * Initialize board structure elements.
 444          */
 445
 446         brd->nasync = brd->maxports;
 447
 448         /* Set up channel variables */
 449         for (i = 0; i < brd->nasync; i++) {
 450
 451                 if (!brd->channels[i])
 452                         continue;
 453
 454                 brd->channels[i]->uart_port.irq = brd->irq;
 455                 brd->channels[i]->uart_port.uartclk = 14745600;
 456                 brd->channels[i]->uart_port.type = PORT_JSM;
 457                 brd->channels[i]->uart_port.iotype = UPIO_MEM;
 458                 brd->channels[i]->uart_port.membase = brd->re_map_membase;
 459                 brd->channels[i]->uart_port.fifosize = 16;
 460                 brd->channels[i]->uart_port.ops = &jsm_ops;
 461                 line = find_first_zero_bit(linemap, MAXLINES);
 462                 if (line >= MAXLINES) {
 463                         printk(KERN_INFO "jsm: linemap is full, added device failed\n");
 464                         continue;
 465                 } else
 466                         set_bit(line, linemap);
 467                 brd->channels[i]->uart_port.line = line;
 468                 rc = uart_add_one_port(&jsm_uart_driver, &brd->channels[i]->uart_port);
 469                 if (rc) {
 470                         printk(KERN_INFO "jsm: Port %d failed. Aborting...\n", i);
 471                         return rc;
 472                 } else
 473                         printk(KERN_INFO "jsm: Port %d added\n", i);
 474         }
 475
 476         jsm_dbg(INIT, &brd->pci_dev, "finish\n");
 477         return 0;
 478 }
 479
 480 int jsm_remove_uart_port(struct jsm_board *brd)
 481 {
 482         int i;
 483         struct jsm_channel *ch;
 484
 485         if (!brd)
 486                 return -ENXIO;
 487
 488         jsm_dbg(INIT, &brd->pci_dev, "start\n");
 489
 490         /*
 491          * Initialize board structure elements.
 492          */
 493
 494         brd->nasync = brd->maxports;
 495
 496         /* Set up channel variables */
 497         for (i = 0; i < brd->nasync; i++) {
 498
 499                 if (!brd->channels[i])
 500                         continue;
 501
 502                 ch = brd->channels[i];
 503
 504                 clear_bit(ch->uart_port.line, linemap);
 505                 uart_remove_one_port(&jsm_uart_driver, &brd->channels[i]->uart_port);
 506         }
 507
 508         jsm_dbg(INIT, &brd->pci_dev, "finish\n");
 509         return 0;
 510 }
 511
 512 void jsm_input(struct jsm_channel *ch)
 513 {
 514         struct jsm_board *bd;
 515         struct tty_struct *tp;
 516         struct tty_port *port;
 517         u32 rmask;
 518         u16 head;
 519         u16 tail;
 520         int data_len;
 521         unsigned long lock_flags;
 522         int len = 0;
 523         int s = 0;
 524         int i = 0;
 525
 526         jsm_dbg(READ, &ch->ch_bd->pci_dev, "start\n");
 527
 528         port = &ch->uart_port.state->port;
 529         tp = port->tty;
 530
 531         bd = ch->ch_bd;
 532         if (!bd)
 533                 return;
 534
 535         spin_lock_irqsave(&ch->ch_lock, lock_flags);
 536
 537         /*
 538          *Figure the number of characters in the buffer.
 539          *Exit immediately if none.
 540          */
 541
 542         rmask = RQUEUEMASK;
 543
 544         head = ch->ch_r_head & rmask;
 545         tail = ch->ch_r_tail & rmask;
 546
 547         data_len = (head - tail) & rmask;
 548         if (data_len == 0) {
 549                 spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
 550                 return;
 551         }
 552
 553         jsm_dbg(READ, &ch->ch_bd->pci_dev, "start\n");
 554
 555         /*
 556          *If the device is not open, or CREAD is off, flush
 557          *input data and return immediately.
 558          */
 559         if (!tp || !C_CREAD(tp)) {
 560
 561                 jsm_dbg(READ, &ch->ch_bd->pci_dev,
 562                         "input. dropping %d bytes on port %d...\n",
 563                         data_len, ch->ch_portnum);
 564                 ch->ch_r_head = tail;
 565
 566                 /* Force queue flow control to be released, if needed */
 567                 jsm_check_queue_flow_control(ch);
 568
 569                 spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
 570                 return;
 571         }
 572
 573         /*
 574          * If we are throttled, simply don't read any data.
 575          */
 576         if (ch->ch_flags & CH_STOPI) {
 577                 spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
 578                 jsm_dbg(READ, &ch->ch_bd->pci_dev,
 579                         "Port %d throttled, not reading any data. head: %x tail: %x\n",
 580                         ch->ch_portnum, head, tail);
 581                 return;
 582         }
 583
 584         jsm_dbg(READ, &ch->ch_bd->pci_dev, "start 2\n");
 585
 586         len = tty_buffer_request_room(port, data_len);
 587
 588         /*
 589          * len now contains the most amount of data we can copy,
 590          * bounded either by the flip buffer size or the amount
 591          * of data the card actually has pending...
 592          */
 593         while (len) {
 594                 s = ((head >= tail) ? head : RQUEUESIZE) - tail;
 595                 s = min(s, len);
 596
 597                 if (s <= 0)
 598                         break;
 599
 600                         /*
 601                          * If conditions are such that ld needs to see all
 602                          * UART errors, we will have to walk each character
 603                          * and error byte and send them to the buffer one at
 604                          * a time.
 605                          */
 606
 607                 if (I_PARMRK(tp) || I_BRKINT(tp) || I_INPCK(tp)) {
 608                         for (i = 0; i < s; i++) {
 609                                 u8 chr   = ch->ch_rqueue[tail + i];
 610                                 u8 error = ch->ch_equeue[tail + i];
 611                                 char flag = TTY_NORMAL;
 612
 613                                 /*
 614                                  * Give the Linux ld the flags in the format it
 615                                  * likes.
 616                                  */
 617                                 if (error & UART_LSR_BI)
 618                                         flag = TTY_BREAK;
 619                                 else if (error & UART_LSR_PE)
 620                                         flag = TTY_PARITY;
 621                                 else if (error & UART_LSR_FE)
 622                                         flag = TTY_FRAME;
 623
 624                                 tty_insert_flip_char(port, chr, flag);
 625                         }
 626                 } else {
 627                         tty_insert_flip_string(port, ch->ch_rqueue + tail, s);
 628                 }
 629                 tail += s;
 630                 len -= s;
 631                 /* Flip queue if needed */
 632                 tail &= rmask;
 633         }
 634
 635         ch->ch_r_tail = tail & rmask;
 636         ch->ch_e_tail = tail & rmask;
 637         jsm_check_queue_flow_control(ch);
 638         spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
 639
 640         /* Tell the tty layer its okay to "eat" the data now */
 641         tty_flip_buffer_push(port);
 642
 643         jsm_dbg(IOCTL, &ch->ch_bd->pci_dev, "finish\n");
 644 }
 645
 646 static void jsm_carrier(struct jsm_channel *ch)
 647 {
 648         struct jsm_board *bd;
 649
 650         int virt_carrier = 0;
 651         int phys_carrier = 0;
 652
 653         jsm_dbg(CARR, &ch->ch_bd->pci_dev, "start\n");
 654
 655         bd = ch->ch_bd;
 656         if (!bd)
 657                 return;
 658
 659         if (ch->ch_mistat & UART_MSR_DCD) {
 660                 jsm_dbg(CARR, &ch->ch_bd->pci_dev, "mistat: %x D_CD: %x\n",
 661                         ch->ch_mistat, ch->ch_mistat & UART_MSR_DCD);
 662                 phys_carrier = 1;
 663         }
 664
 665         if (ch->ch_c_cflag & CLOCAL)
 666                 virt_carrier = 1;
 667
 668         jsm_dbg(CARR, &ch->ch_bd->pci_dev, "DCD: physical: %d virt: %d\n",
 669                 phys_carrier, virt_carrier);
 670
 671         /*
 672          * Test for a VIRTUAL carrier transition to HIGH.
 673          */
 674         if (((ch->ch_flags & CH_FCAR) == 0) && (virt_carrier == 1)) {
 675
 676                 /*
 677                  * When carrier rises, wake any threads waiting
 678                  * for carrier in the open routine.
 679                  */
 680
 681                 jsm_dbg(CARR, &ch->ch_bd->pci_dev, "carrier: virt DCD rose\n");
 682
 683                 if (waitqueue_active(&(ch->ch_flags_wait)))
 684                         wake_up_interruptible(&ch->ch_flags_wait);
 685         }
 686
 687         /*
 688          * Test for a PHYSICAL carrier transition to HIGH.
 689          */
 690         if (((ch->ch_flags & CH_CD) == 0) && (phys_carrier == 1)) {
 691
 692                 /*
 693                  * When carrier rises, wake any threads waiting
 694                  * for carrier in the open routine.
 695                  */
 696
 697                 jsm_dbg(CARR, &ch->ch_bd->pci_dev,
 698                         "carrier: physical 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 transition to low, so long as we aren't
 706          *  currently ignoring physical transitions (which is what "virtual
 707          *  carrier" indicates).
 708          *
 709          *  The transition of the virtual carrier to low really doesn't
 710          *  matter... it really only means "ignore carrier state", not
 711          *  "make pretend that carrier is there".
 712          */
 713         if ((virt_carrier == 0) && ((ch->ch_flags & CH_CD) != 0)
 714                         && (phys_carrier == 0)) {
 715                 /*
 716                  *      When carrier drops:
 717                  *
 718                  *      Drop carrier on all open units.
 719                  *
 720                  *      Flush queues, waking up any task waiting in the
 721                  *      line discipline.
 722                  *
 723                  *      Send a hangup to the control terminal.
 724                  *
 725                  *      Enable all select calls.
 726                  */
 727                 if (waitqueue_active(&(ch->ch_flags_wait)))
 728                         wake_up_interruptible(&ch->ch_flags_wait);
 729         }
 730
 731         /*
 732          *  Make sure that our cached values reflect the current reality.
 733          */
 734         if (virt_carrier == 1)
 735                 ch->ch_flags |= CH_FCAR;
 736         else
 737                 ch->ch_flags &= ~CH_FCAR;
 738
 739         if (phys_carrier == 1)
 740                 ch->ch_flags |= CH_CD;
 741         else
 742                 ch->ch_flags &= ~CH_CD;
 743 }
 744
 745
 746 void jsm_check_queue_flow_control(struct jsm_channel *ch)
 747 {
 748         struct board_ops *bd_ops = ch->ch_bd->bd_ops;
 749         int qleft;
 750
 751         /* Store how much space we have left in the queue */
 752         if ((qleft = ch->ch_r_tail - ch->ch_r_head - 1) < 0)
 753                 qleft += RQUEUEMASK + 1;
 754
 755         /*
 756          * Check to see if we should enforce flow control on our queue because
 757          * the ld (or user) isn't reading data out of our queue fast enuf.
 758          *
 759          * NOTE: This is done based on what the current flow control of the
 760          * port is set for.
 761          *
 762          * 1) HWFLOW (RTS) - Turn off the UART's Receive interrupt.
 763          *      This will cause the UART's FIFO to back up, and force
 764          *      the RTS signal to be dropped.
 765          * 2) SWFLOW (IXOFF) - Keep trying to send a stop character to
 766          *      the other side, in hopes it will stop sending data to us.
 767          * 3) NONE - Nothing we can do.  We will simply drop any extra data
 768          *      that gets sent into us when the queue fills up.
 769          */
 770         if (qleft < 256) {
 771                 /* HWFLOW */
 772                 if (ch->ch_c_cflag & CRTSCTS) {
 773                         if (!(ch->ch_flags & CH_RECEIVER_OFF)) {
 774                                 bd_ops->disable_receiver(ch);
 775                                 ch->ch_flags |= (CH_RECEIVER_OFF);
 776                                 jsm_dbg(READ, &ch->ch_bd->pci_dev,
 777                                         "Internal queue hit hilevel mark (%d)! Turning off interrupts\n",
 778                                         qleft);
 779                         }
 780                 }
 781                 /* SWFLOW */
 782                 else if (ch->ch_c_iflag & IXOFF) {
 783                         if (ch->ch_stops_sent <= MAX_STOPS_SENT) {
 784                                 bd_ops->send_stop_character(ch);
 785                                 ch->ch_stops_sent++;
 786                                 jsm_dbg(READ, &ch->ch_bd->pci_dev,
 787                                         "Sending stop char! Times sent: %x\n",
 788                                         ch->ch_stops_sent);
 789                         }
 790                 }
 791         }
 792
 793         /*
 794          * Check to see if we should unenforce flow control because
 795          * ld (or user) finally read enuf data out of our queue.
 796          *
 797          * NOTE: This is done based on what the current flow control of the
 798          * port is set for.
 799          *
 800          * 1) HWFLOW (RTS) - Turn back on the UART's Receive interrupt.
 801          *      This will cause the UART's FIFO to raise RTS back up,
 802          *      which will allow the other side to start sending data again.
 803          * 2) SWFLOW (IXOFF) - Send a start character to
 804          *      the other side, so it will start sending data to us again.
 805          * 3) NONE - Do nothing. Since we didn't do anything to turn off the
 806          *      other side, we don't need to do anything now.
 807          */
 808         if (qleft > (RQUEUESIZE / 2)) {
 809                 /* HWFLOW */
 810                 if (ch->ch_c_cflag & CRTSCTS) {
 811                         if (ch->ch_flags & CH_RECEIVER_OFF) {
 812                                 bd_ops->enable_receiver(ch);
 813                                 ch->ch_flags &= ~(CH_RECEIVER_OFF);
 814                                 jsm_dbg(READ, &ch->ch_bd->pci_dev,
 815                                         "Internal queue hit lowlevel mark (%d)! Turning on interrupts\n",
 816                                         qleft);
 817                         }
 818                 }
 819                 /* SWFLOW */
 820                 else if (ch->ch_c_iflag & IXOFF && ch->ch_stops_sent) {
 821                         ch->ch_stops_sent = 0;
 822                         bd_ops->send_start_character(ch);
 823                         jsm_dbg(READ, &ch->ch_bd->pci_dev,
 824                                 "Sending start char!\n");
 825                 }
 826         }
 827 }