xref: /openbmc/linux/drivers/tty/serial/jsm/jsm_tty.c (revision bec5b814)
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 
jsm_get_mstat(struct jsm_channel * ch)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 
jsm_tty_tx_empty(struct uart_port * port)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  */
jsm_tty_get_mctrl(struct uart_port * port)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  */
jsm_tty_set_mctrl(struct uart_port * port,unsigned int mctrl)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  */
jsm_tty_write(struct uart_port * port)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 
jsm_tty_start_tx(struct uart_port * port)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 
jsm_tty_stop_tx(struct uart_port * port)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 
jsm_tty_send_xchar(struct uart_port * port,char ch)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 
jsm_tty_stop_rx(struct uart_port * port)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 
jsm_tty_break(struct uart_port * port,int break_state)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 
jsm_tty_open(struct uart_port * port)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 
jsm_tty_close(struct uart_port * port)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 
jsm_tty_set_termios(struct uart_port * port,struct ktermios * termios,const struct ktermios * old_termios)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 	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 
jsm_tty_type(struct uart_port * port)323 static const char *jsm_tty_type(struct uart_port *port)
324 {
325 	return "jsm";
326 }
327 
jsm_tty_release_port(struct uart_port * port)328 static void jsm_tty_release_port(struct uart_port *port)
329 {
330 }
331 
jsm_tty_request_port(struct uart_port * port)332 static int jsm_tty_request_port(struct uart_port *port)
333 {
334 	return 0;
335 }
336 
jsm_config_port(struct uart_port * port,int flags)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  */
jsm_tty_init(struct jsm_board * brd)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 
jsm_uart_port_init(struct jsm_board * brd)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 
jsm_remove_uart_port(struct jsm_board * brd)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 
jsm_input(struct jsm_channel * ch)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 
jsm_carrier(struct jsm_channel * ch)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 
jsm_check_queue_flow_control(struct jsm_channel * ch)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 	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