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 23static DECLARE_BITMAP(linemap, MAXLINES); 24 25static void jsm_carrier(struct jsm_channel *ch); 26 27static 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 55static 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 */ 63static 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 */ 86static 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 */ 115static 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 123static 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 136static 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 148static 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 uart_port_lock_irqsave(port, &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 uart_port_unlock_irqrestore(port, lock_flags); 163} 164 165static 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 173static 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 uart_port_lock_irqsave(port, &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 uart_port_unlock_irqrestore(port, lock_flags); 186} 187 188static 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 uart_port_lock_irqsave(port, &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 uart_port_unlock_irqrestore(port, lock_flags); 265 266 jsm_dbg(OPEN, &channel->ch_bd->pci_dev, "finish\n"); 267 return 0; 268} 269 270static 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 302static void jsm_tty_set_termios(struct uart_port *port, 303 struct ktermios *termios, 304 const 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 uart_port_lock_irqsave(port, &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 uart_port_unlock_irqrestore(port, lock_flags); 321} 322 323static const char *jsm_tty_type(struct uart_port *port) 324{ 325 return "jsm"; 326} 327 328static void jsm_tty_release_port(struct uart_port *port) 329{ 330} 331 332static int jsm_tty_request_port(struct uart_port *port) 333{ 334 return 0; 335} 336 337static void jsm_config_port(struct uart_port *port, int flags) 338{ 339 port->type = PORT_JSM; 340} 341 342static 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 */ 366int 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 432int 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 480int 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 512void 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 646static 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 746void 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 qleft = ch->ch_r_tail - ch->ch_r_head - 1; 753 if (qleft < 0) 754 qleft += RQUEUEMASK + 1; 755 756 /* 757 * Check to see if we should enforce flow control on our queue because 758 * the ld (or user) isn't reading data out of our queue fast enuf. 759 * 760 * NOTE: This is done based on what the current flow control of the 761 * port is set for. 762 * 763 * 1) HWFLOW (RTS) - Turn off the UART's Receive interrupt. 764 * This will cause the UART's FIFO to back up, and force 765 * the RTS signal to be dropped. 766 * 2) SWFLOW (IXOFF) - Keep trying to send a stop character to 767 * the other side, in hopes it will stop sending data to us. 768 * 3) NONE - Nothing we can do. We will simply drop any extra data 769 * that gets sent into us when the queue fills up. 770 */ 771 if (qleft < 256) { 772 /* HWFLOW */ 773 if (ch->ch_c_cflag & CRTSCTS) { 774 if (!(ch->ch_flags & CH_RECEIVER_OFF)) { 775 bd_ops->disable_receiver(ch); 776 ch->ch_flags |= (CH_RECEIVER_OFF); 777 jsm_dbg(READ, &ch->ch_bd->pci_dev, 778 "Internal queue hit hilevel mark (%d)! Turning off interrupts\n", 779 qleft); 780 } 781 } 782 /* SWFLOW */ 783 else if (ch->ch_c_iflag & IXOFF) { 784 if (ch->ch_stops_sent <= MAX_STOPS_SENT) { 785 bd_ops->send_stop_character(ch); 786 ch->ch_stops_sent++; 787 jsm_dbg(READ, &ch->ch_bd->pci_dev, 788 "Sending stop char! Times sent: %x\n", 789 ch->ch_stops_sent); 790 } 791 } 792 } 793 794 /* 795 * Check to see if we should unenforce flow control because 796 * ld (or user) finally read enuf data out of our queue. 797 * 798 * NOTE: This is done based on what the current flow control of the 799 * port is set for. 800 * 801 * 1) HWFLOW (RTS) - Turn back on the UART's Receive interrupt. 802 * This will cause the UART's FIFO to raise RTS back up, 803 * which will allow the other side to start sending data again. 804 * 2) SWFLOW (IXOFF) - Send a start character to 805 * the other side, so it will start sending data to us again. 806 * 3) NONE - Do nothing. Since we didn't do anything to turn off the 807 * other side, we don't need to do anything now. 808 */ 809 if (qleft > (RQUEUESIZE / 2)) { 810 /* HWFLOW */ 811 if (ch->ch_c_cflag & CRTSCTS) { 812 if (ch->ch_flags & CH_RECEIVER_OFF) { 813 bd_ops->enable_receiver(ch); 814 ch->ch_flags &= ~(CH_RECEIVER_OFF); 815 jsm_dbg(READ, &ch->ch_bd->pci_dev, 816 "Internal queue hit lowlevel mark (%d)! Turning on interrupts\n", 817 qleft); 818 } 819 } 820 /* SWFLOW */ 821 else if (ch->ch_c_iflag & IXOFF && ch->ch_stops_sent) { 822 ch->ch_stops_sent = 0; 823 bd_ops->send_start_character(ch); 824 jsm_dbg(READ, &ch->ch_bd->pci_dev, 825 "Sending start char!\n"); 826 } 827 } 828} 829