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 	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 
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 	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 
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 	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 
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 				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 
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.dev = &brd->pci_dev->dev;
455 		brd->channels[i]->uart_port.irq = brd->irq;
456 		brd->channels[i]->uart_port.uartclk = 14745600;
457 		brd->channels[i]->uart_port.type = PORT_JSM;
458 		brd->channels[i]->uart_port.iotype = UPIO_MEM;
459 		brd->channels[i]->uart_port.membase = brd->re_map_membase;
460 		brd->channels[i]->uart_port.fifosize = 16;
461 		brd->channels[i]->uart_port.ops = &jsm_ops;
462 		line = find_first_zero_bit(linemap, MAXLINES);
463 		if (line >= MAXLINES) {
464 			printk(KERN_INFO "jsm: linemap is full, added device failed\n");
465 			continue;
466 		} else
467 			set_bit(line, linemap);
468 		brd->channels[i]->uart_port.line = line;
469 		rc = uart_add_one_port(&jsm_uart_driver, &brd->channels[i]->uart_port);
470 		if (rc) {
471 			printk(KERN_INFO "jsm: Port %d failed. Aborting...\n", i);
472 			return rc;
473 		} else
474 			printk(KERN_INFO "jsm: Port %d added\n", i);
475 	}
476 
477 	jsm_dbg(INIT, &brd->pci_dev, "finish\n");
478 	return 0;
479 }
480 
481 int jsm_remove_uart_port(struct jsm_board *brd)
482 {
483 	int i;
484 	struct jsm_channel *ch;
485 
486 	if (!brd)
487 		return -ENXIO;
488 
489 	jsm_dbg(INIT, &brd->pci_dev, "start\n");
490 
491 	/*
492 	 * Initialize board structure elements.
493 	 */
494 
495 	brd->nasync = brd->maxports;
496 
497 	/* Set up channel variables */
498 	for (i = 0; i < brd->nasync; i++) {
499 
500 		if (!brd->channels[i])
501 			continue;
502 
503 		ch = brd->channels[i];
504 
505 		clear_bit(ch->uart_port.line, linemap);
506 		uart_remove_one_port(&jsm_uart_driver, &brd->channels[i]->uart_port);
507 	}
508 
509 	jsm_dbg(INIT, &brd->pci_dev, "finish\n");
510 	return 0;
511 }
512 
513 void jsm_input(struct jsm_channel *ch)
514 {
515 	struct jsm_board *bd;
516 	struct tty_struct *tp;
517 	struct tty_port *port;
518 	u32 rmask;
519 	u16 head;
520 	u16 tail;
521 	int data_len;
522 	unsigned long lock_flags;
523 	int len = 0;
524 	int s = 0;
525 	int i = 0;
526 
527 	jsm_dbg(READ, &ch->ch_bd->pci_dev, "start\n");
528 
529 	port = &ch->uart_port.state->port;
530 	tp = port->tty;
531 
532 	bd = ch->ch_bd;
533 	if (!bd)
534 		return;
535 
536 	spin_lock_irqsave(&ch->ch_lock, lock_flags);
537 
538 	/*
539 	 *Figure the number of characters in the buffer.
540 	 *Exit immediately if none.
541 	 */
542 
543 	rmask = RQUEUEMASK;
544 
545 	head = ch->ch_r_head & rmask;
546 	tail = ch->ch_r_tail & rmask;
547 
548 	data_len = (head - tail) & rmask;
549 	if (data_len == 0) {
550 		spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
551 		return;
552 	}
553 
554 	jsm_dbg(READ, &ch->ch_bd->pci_dev, "start\n");
555 
556 	/*
557 	 *If the device is not open, or CREAD is off, flush
558 	 *input data and return immediately.
559 	 */
560 	if (!tp || !C_CREAD(tp)) {
561 
562 		jsm_dbg(READ, &ch->ch_bd->pci_dev,
563 			"input. dropping %d bytes on port %d...\n",
564 			data_len, ch->ch_portnum);
565 		ch->ch_r_head = tail;
566 
567 		/* Force queue flow control to be released, if needed */
568 		jsm_check_queue_flow_control(ch);
569 
570 		spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
571 		return;
572 	}
573 
574 	/*
575 	 * If we are throttled, simply don't read any data.
576 	 */
577 	if (ch->ch_flags & CH_STOPI) {
578 		spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
579 		jsm_dbg(READ, &ch->ch_bd->pci_dev,
580 			"Port %d throttled, not reading any data. head: %x tail: %x\n",
581 			ch->ch_portnum, head, tail);
582 		return;
583 	}
584 
585 	jsm_dbg(READ, &ch->ch_bd->pci_dev, "start 2\n");
586 
587 	len = tty_buffer_request_room(port, data_len);
588 
589 	/*
590 	 * len now contains the most amount of data we can copy,
591 	 * bounded either by the flip buffer size or the amount
592 	 * of data the card actually has pending...
593 	 */
594 	while (len) {
595 		s = ((head >= tail) ? head : RQUEUESIZE) - tail;
596 		s = min(s, len);
597 
598 		if (s <= 0)
599 			break;
600 
601 			/*
602 			 * If conditions are such that ld needs to see all
603 			 * UART errors, we will have to walk each character
604 			 * and error byte and send them to the buffer one at
605 			 * a time.
606 			 */
607 
608 		if (I_PARMRK(tp) || I_BRKINT(tp) || I_INPCK(tp)) {
609 			for (i = 0; i < s; i++) {
610 				u8 chr   = ch->ch_rqueue[tail + i];
611 				u8 error = ch->ch_equeue[tail + i];
612 				char flag = TTY_NORMAL;
613 
614 				/*
615 				 * Give the Linux ld the flags in the format it
616 				 * likes.
617 				 */
618 				if (error & UART_LSR_BI)
619 					flag = TTY_BREAK;
620 				else if (error & UART_LSR_PE)
621 					flag = TTY_PARITY;
622 				else if (error & UART_LSR_FE)
623 					flag = TTY_FRAME;
624 
625 				tty_insert_flip_char(port, chr, flag);
626 			}
627 		} else {
628 			tty_insert_flip_string(port, ch->ch_rqueue + tail, s);
629 		}
630 		tail += s;
631 		len -= s;
632 		/* Flip queue if needed */
633 		tail &= rmask;
634 	}
635 
636 	ch->ch_r_tail = tail & rmask;
637 	ch->ch_e_tail = tail & rmask;
638 	jsm_check_queue_flow_control(ch);
639 	spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
640 
641 	/* Tell the tty layer its okay to "eat" the data now */
642 	tty_flip_buffer_push(port);
643 
644 	jsm_dbg(IOCTL, &ch->ch_bd->pci_dev, "finish\n");
645 }
646 
647 static void jsm_carrier(struct jsm_channel *ch)
648 {
649 	struct jsm_board *bd;
650 
651 	int virt_carrier = 0;
652 	int phys_carrier = 0;
653 
654 	jsm_dbg(CARR, &ch->ch_bd->pci_dev, "start\n");
655 
656 	bd = ch->ch_bd;
657 	if (!bd)
658 		return;
659 
660 	if (ch->ch_mistat & UART_MSR_DCD) {
661 		jsm_dbg(CARR, &ch->ch_bd->pci_dev, "mistat: %x D_CD: %x\n",
662 			ch->ch_mistat, ch->ch_mistat & UART_MSR_DCD);
663 		phys_carrier = 1;
664 	}
665 
666 	if (ch->ch_c_cflag & CLOCAL)
667 		virt_carrier = 1;
668 
669 	jsm_dbg(CARR, &ch->ch_bd->pci_dev, "DCD: physical: %d virt: %d\n",
670 		phys_carrier, virt_carrier);
671 
672 	/*
673 	 * Test for a VIRTUAL carrier transition to HIGH.
674 	 */
675 	if (((ch->ch_flags & CH_FCAR) == 0) && (virt_carrier == 1)) {
676 
677 		/*
678 		 * When carrier rises, wake any threads waiting
679 		 * for carrier in the open routine.
680 		 */
681 
682 		jsm_dbg(CARR, &ch->ch_bd->pci_dev, "carrier: virt DCD rose\n");
683 
684 		if (waitqueue_active(&(ch->ch_flags_wait)))
685 			wake_up_interruptible(&ch->ch_flags_wait);
686 	}
687 
688 	/*
689 	 * Test for a PHYSICAL carrier transition to HIGH.
690 	 */
691 	if (((ch->ch_flags & CH_CD) == 0) && (phys_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,
699 			"carrier: physical DCD rose\n");
700 
701 		if (waitqueue_active(&(ch->ch_flags_wait)))
702 			wake_up_interruptible(&ch->ch_flags_wait);
703 	}
704 
705 	/*
706 	 *  Test for a PHYSICAL transition to low, so long as we aren't
707 	 *  currently ignoring physical transitions (which is what "virtual
708 	 *  carrier" indicates).
709 	 *
710 	 *  The transition of the virtual carrier to low really doesn't
711 	 *  matter... it really only means "ignore carrier state", not
712 	 *  "make pretend that carrier is there".
713 	 */
714 	if ((virt_carrier == 0) && ((ch->ch_flags & CH_CD) != 0)
715 			&& (phys_carrier == 0)) {
716 		/*
717 		 *	When carrier drops:
718 		 *
719 		 *	Drop carrier on all open units.
720 		 *
721 		 *	Flush queues, waking up any task waiting in the
722 		 *	line discipline.
723 		 *
724 		 *	Send a hangup to the control terminal.
725 		 *
726 		 *	Enable all select calls.
727 		 */
728 		if (waitqueue_active(&(ch->ch_flags_wait)))
729 			wake_up_interruptible(&ch->ch_flags_wait);
730 	}
731 
732 	/*
733 	 *  Make sure that our cached values reflect the current reality.
734 	 */
735 	if (virt_carrier == 1)
736 		ch->ch_flags |= CH_FCAR;
737 	else
738 		ch->ch_flags &= ~CH_FCAR;
739 
740 	if (phys_carrier == 1)
741 		ch->ch_flags |= CH_CD;
742 	else
743 		ch->ch_flags &= ~CH_CD;
744 }
745 
746 
747 void jsm_check_queue_flow_control(struct jsm_channel *ch)
748 {
749 	struct board_ops *bd_ops = ch->ch_bd->bd_ops;
750 	int qleft;
751 
752 	/* Store how much space we have left in the queue */
753 	qleft = ch->ch_r_tail - ch->ch_r_head - 1;
754 	if (qleft < 0)
755 		qleft += RQUEUEMASK + 1;
756 
757 	/*
758 	 * Check to see if we should enforce flow control on our queue because
759 	 * the ld (or user) isn't reading data out of our queue fast enuf.
760 	 *
761 	 * NOTE: This is done based on what the current flow control of the
762 	 * port is set for.
763 	 *
764 	 * 1) HWFLOW (RTS) - Turn off the UART's Receive interrupt.
765 	 *	This will cause the UART's FIFO to back up, and force
766 	 *	the RTS signal to be dropped.
767 	 * 2) SWFLOW (IXOFF) - Keep trying to send a stop character to
768 	 *	the other side, in hopes it will stop sending data to us.
769 	 * 3) NONE - Nothing we can do.  We will simply drop any extra data
770 	 *	that gets sent into us when the queue fills up.
771 	 */
772 	if (qleft < 256) {
773 		/* HWFLOW */
774 		if (ch->ch_c_cflag & CRTSCTS) {
775 			if (!(ch->ch_flags & CH_RECEIVER_OFF)) {
776 				bd_ops->disable_receiver(ch);
777 				ch->ch_flags |= (CH_RECEIVER_OFF);
778 				jsm_dbg(READ, &ch->ch_bd->pci_dev,
779 					"Internal queue hit hilevel mark (%d)! Turning off interrupts\n",
780 					qleft);
781 			}
782 		}
783 		/* SWFLOW */
784 		else if (ch->ch_c_iflag & IXOFF) {
785 			if (ch->ch_stops_sent <= MAX_STOPS_SENT) {
786 				bd_ops->send_stop_character(ch);
787 				ch->ch_stops_sent++;
788 				jsm_dbg(READ, &ch->ch_bd->pci_dev,
789 					"Sending stop char! Times sent: %x\n",
790 					ch->ch_stops_sent);
791 			}
792 		}
793 	}
794 
795 	/*
796 	 * Check to see if we should unenforce flow control because
797 	 * ld (or user) finally read enuf data out of our queue.
798 	 *
799 	 * NOTE: This is done based on what the current flow control of the
800 	 * port is set for.
801 	 *
802 	 * 1) HWFLOW (RTS) - Turn back on the UART's Receive interrupt.
803 	 *	This will cause the UART's FIFO to raise RTS back up,
804 	 *	which will allow the other side to start sending data again.
805 	 * 2) SWFLOW (IXOFF) - Send a start character to
806 	 *	the other side, so it will start sending data to us again.
807 	 * 3) NONE - Do nothing. Since we didn't do anything to turn off the
808 	 *	other side, we don't need to do anything now.
809 	 */
810 	if (qleft > (RQUEUESIZE / 2)) {
811 		/* HWFLOW */
812 		if (ch->ch_c_cflag & CRTSCTS) {
813 			if (ch->ch_flags & CH_RECEIVER_OFF) {
814 				bd_ops->enable_receiver(ch);
815 				ch->ch_flags &= ~(CH_RECEIVER_OFF);
816 				jsm_dbg(READ, &ch->ch_bd->pci_dev,
817 					"Internal queue hit lowlevel mark (%d)! Turning on interrupts\n",
818 					qleft);
819 			}
820 		}
821 		/* SWFLOW */
822 		else if (ch->ch_c_iflag & IXOFF && ch->ch_stops_sent) {
823 			ch->ch_stops_sent = 0;
824 			bd_ops->send_start_character(ch);
825 			jsm_dbg(READ, &ch->ch_bd->pci_dev,
826 				"Sending start char!\n");
827 		}
828 	}
829 }
830