xref: /linux/drivers/tty/serial/max3100.c (revision e3b3d0f549c1d19b94e6ac55c66643166ea649ef)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *
4  *  Copyright (C) 2008 Christian Pellegrin <chripell@evolware.org>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  *
12  * Notes: the MAX3100 doesn't provide an interrupt on CTS so we have
13  * to use polling for flow control. TX empty IRQ is unusable, since
14  * writing conf clears FIFO buffer and we cannot have this interrupt
15  * always asking us for attention.
16  *
17  * Example platform data:
18 
19  static struct plat_max3100 max3100_plat_data = {
20  .loopback = 0,
21  .crystal = 0,
22  .poll_time = 100,
23  };
24 
25  static struct spi_board_info spi_board_info[] = {
26  {
27  .modalias	= "max3100",
28  .platform_data	= &max3100_plat_data,
29  .irq		= IRQ_EINT12,
30  .max_speed_hz	= 5*1000*1000,
31  .chip_select	= 0,
32  },
33  };
34 
35  * The initial minor number is 209 in the low-density serial port:
36  * mknod /dev/ttyMAX0 c 204 209
37  */
38 
39 #define MAX3100_MAJOR 204
40 #define MAX3100_MINOR 209
41 /* 4 MAX3100s should be enough for everyone */
42 #define MAX_MAX3100 4
43 
44 #include <linux/delay.h>
45 #include <linux/slab.h>
46 #include <linux/device.h>
47 #include <linux/module.h>
48 #include <linux/serial_core.h>
49 #include <linux/serial.h>
50 #include <linux/spi/spi.h>
51 #include <linux/freezer.h>
52 #include <linux/tty.h>
53 #include <linux/tty_flip.h>
54 
55 #include <linux/serial_max3100.h>
56 
57 #define MAX3100_C    (1<<14)
58 #define MAX3100_D    (0<<14)
59 #define MAX3100_W    (1<<15)
60 #define MAX3100_RX   (0<<15)
61 
62 #define MAX3100_WC   (MAX3100_W  | MAX3100_C)
63 #define MAX3100_RC   (MAX3100_RX | MAX3100_C)
64 #define MAX3100_WD   (MAX3100_W  | MAX3100_D)
65 #define MAX3100_RD   (MAX3100_RX | MAX3100_D)
66 #define MAX3100_CMD  (3 << 14)
67 
68 #define MAX3100_T    (1<<14)
69 #define MAX3100_R    (1<<15)
70 
71 #define MAX3100_FEN  (1<<13)
72 #define MAX3100_SHDN (1<<12)
73 #define MAX3100_TM   (1<<11)
74 #define MAX3100_RM   (1<<10)
75 #define MAX3100_PM   (1<<9)
76 #define MAX3100_RAM  (1<<8)
77 #define MAX3100_IR   (1<<7)
78 #define MAX3100_ST   (1<<6)
79 #define MAX3100_PE   (1<<5)
80 #define MAX3100_L    (1<<4)
81 #define MAX3100_BAUD (0xf)
82 
83 #define MAX3100_TE   (1<<10)
84 #define MAX3100_RAFE (1<<10)
85 #define MAX3100_RTS  (1<<9)
86 #define MAX3100_CTS  (1<<9)
87 #define MAX3100_PT   (1<<8)
88 #define MAX3100_DATA (0xff)
89 
90 #define MAX3100_RT   (MAX3100_R | MAX3100_T)
91 #define MAX3100_RTC  (MAX3100_RT | MAX3100_CTS | MAX3100_RAFE)
92 
93 /* the following simulate a status reg for ignore_status_mask */
94 #define MAX3100_STATUS_PE 1
95 #define MAX3100_STATUS_FE 2
96 #define MAX3100_STATUS_OE 4
97 
98 struct max3100_port {
99 	struct uart_port port;
100 	struct spi_device *spi;
101 
102 	int cts;	        /* last CTS received for flow ctrl */
103 	int tx_empty;		/* last TX empty bit */
104 
105 	spinlock_t conf_lock;	/* shared data */
106 	int conf_commit;	/* need to make changes */
107 	int conf;		/* configuration for the MAX31000
108 				 * (bits 0-7, bits 8-11 are irqs) */
109 	int rts_commit;	        /* need to change rts */
110 	int rts;		/* rts status */
111 	int baud;		/* current baud rate */
112 
113 	int parity;		/* keeps track if we should send parity */
114 #define MAX3100_PARITY_ON 1
115 #define MAX3100_PARITY_ODD 2
116 #define MAX3100_7BIT 4
117 	int rx_enabled;	        /* if we should rx chars */
118 
119 	int irq;		/* irq assigned to the max3100 */
120 
121 	int minor;		/* minor number */
122 	int crystal;		/* 1 if 3.6864Mhz crystal 0 for 1.8432 */
123 	int loopback;		/* 1 if we are in loopback mode */
124 
125 	/* for handling irqs: need workqueue since we do spi_sync */
126 	struct workqueue_struct *workqueue;
127 	struct work_struct work;
128 	/* set to 1 to make the workhandler exit as soon as possible */
129 	int  force_end_work;
130 	/* need to know we are suspending to avoid deadlock on workqueue */
131 	int suspending;
132 
133 	/* hook for suspending MAX3100 via dedicated pin */
134 	void (*max3100_hw_suspend) (int suspend);
135 
136 	/* poll time (in ms) for ctrl lines */
137 	int poll_time;
138 	/* and its timer */
139 	struct timer_list	timer;
140 };
141 
142 static struct max3100_port *max3100s[MAX_MAX3100]; /* the chips */
143 static DEFINE_MUTEX(max3100s_lock);		   /* race on probe */
144 
145 static int max3100_do_parity(struct max3100_port *s, u16 c)
146 {
147 	int parity;
148 
149 	if (s->parity & MAX3100_PARITY_ODD)
150 		parity = 1;
151 	else
152 		parity = 0;
153 
154 	if (s->parity & MAX3100_7BIT)
155 		c &= 0x7f;
156 	else
157 		c &= 0xff;
158 
159 	parity = parity ^ (hweight8(c) & 1);
160 	return parity;
161 }
162 
163 static int max3100_check_parity(struct max3100_port *s, u16 c)
164 {
165 	return max3100_do_parity(s, c) == ((c >> 8) & 1);
166 }
167 
168 static void max3100_calc_parity(struct max3100_port *s, u16 *c)
169 {
170 	if (s->parity & MAX3100_7BIT)
171 		*c &= 0x7f;
172 	else
173 		*c &= 0xff;
174 
175 	if (s->parity & MAX3100_PARITY_ON)
176 		*c |= max3100_do_parity(s, *c) << 8;
177 }
178 
179 static void max3100_work(struct work_struct *w);
180 
181 static void max3100_dowork(struct max3100_port *s)
182 {
183 	if (!s->force_end_work && !freezing(current) && !s->suspending)
184 		queue_work(s->workqueue, &s->work);
185 }
186 
187 static void max3100_timeout(unsigned long data)
188 {
189 	struct max3100_port *s = (struct max3100_port *)data;
190 
191 	if (s->port.state) {
192 		max3100_dowork(s);
193 		mod_timer(&s->timer, jiffies + s->poll_time);
194 	}
195 }
196 
197 static int max3100_sr(struct max3100_port *s, u16 tx, u16 *rx)
198 {
199 	struct spi_message message;
200 	u16 etx, erx;
201 	int status;
202 	struct spi_transfer tran = {
203 		.tx_buf = &etx,
204 		.rx_buf = &erx,
205 		.len = 2,
206 	};
207 
208 	etx = cpu_to_be16(tx);
209 	spi_message_init(&message);
210 	spi_message_add_tail(&tran, &message);
211 	status = spi_sync(s->spi, &message);
212 	if (status) {
213 		dev_warn(&s->spi->dev, "error while calling spi_sync\n");
214 		return -EIO;
215 	}
216 	*rx = be16_to_cpu(erx);
217 	s->tx_empty = (*rx & MAX3100_T) > 0;
218 	dev_dbg(&s->spi->dev, "%04x - %04x\n", tx, *rx);
219 	return 0;
220 }
221 
222 static int max3100_handlerx(struct max3100_port *s, u16 rx)
223 {
224 	unsigned int ch, flg, status = 0;
225 	int ret = 0, cts;
226 
227 	if (rx & MAX3100_R && s->rx_enabled) {
228 		dev_dbg(&s->spi->dev, "%s\n", __func__);
229 		ch = rx & (s->parity & MAX3100_7BIT ? 0x7f : 0xff);
230 		if (rx & MAX3100_RAFE) {
231 			s->port.icount.frame++;
232 			flg = TTY_FRAME;
233 			status |= MAX3100_STATUS_FE;
234 		} else {
235 			if (s->parity & MAX3100_PARITY_ON) {
236 				if (max3100_check_parity(s, rx)) {
237 					s->port.icount.rx++;
238 					flg = TTY_NORMAL;
239 				} else {
240 					s->port.icount.parity++;
241 					flg = TTY_PARITY;
242 					status |= MAX3100_STATUS_PE;
243 				}
244 			} else {
245 				s->port.icount.rx++;
246 				flg = TTY_NORMAL;
247 			}
248 		}
249 		uart_insert_char(&s->port, status, MAX3100_STATUS_OE, ch, flg);
250 		ret = 1;
251 	}
252 
253 	cts = (rx & MAX3100_CTS) > 0;
254 	if (s->cts != cts) {
255 		s->cts = cts;
256 		uart_handle_cts_change(&s->port, cts ? TIOCM_CTS : 0);
257 	}
258 
259 	return ret;
260 }
261 
262 static void max3100_work(struct work_struct *w)
263 {
264 	struct max3100_port *s = container_of(w, struct max3100_port, work);
265 	int rxchars;
266 	u16 tx, rx;
267 	int conf, cconf, crts;
268 	struct circ_buf *xmit = &s->port.state->xmit;
269 
270 	dev_dbg(&s->spi->dev, "%s\n", __func__);
271 
272 	rxchars = 0;
273 	do {
274 		spin_lock(&s->conf_lock);
275 		conf = s->conf;
276 		cconf = s->conf_commit;
277 		s->conf_commit = 0;
278 		crts = s->rts_commit;
279 		s->rts_commit = 0;
280 		spin_unlock(&s->conf_lock);
281 		if (cconf)
282 			max3100_sr(s, MAX3100_WC | conf, &rx);
283 		if (crts) {
284 			max3100_sr(s, MAX3100_WD | MAX3100_TE |
285 				   (s->rts ? MAX3100_RTS : 0), &rx);
286 			rxchars += max3100_handlerx(s, rx);
287 		}
288 
289 		max3100_sr(s, MAX3100_RD, &rx);
290 		rxchars += max3100_handlerx(s, rx);
291 
292 		if (rx & MAX3100_T) {
293 			tx = 0xffff;
294 			if (s->port.x_char) {
295 				tx = s->port.x_char;
296 				s->port.icount.tx++;
297 				s->port.x_char = 0;
298 			} else if (!uart_circ_empty(xmit) &&
299 				   !uart_tx_stopped(&s->port)) {
300 				tx = xmit->buf[xmit->tail];
301 				xmit->tail = (xmit->tail + 1) &
302 					(UART_XMIT_SIZE - 1);
303 				s->port.icount.tx++;
304 			}
305 			if (tx != 0xffff) {
306 				max3100_calc_parity(s, &tx);
307 				tx |= MAX3100_WD | (s->rts ? MAX3100_RTS : 0);
308 				max3100_sr(s, tx, &rx);
309 				rxchars += max3100_handlerx(s, rx);
310 			}
311 		}
312 
313 		if (rxchars > 16) {
314 			tty_flip_buffer_push(&s->port.state->port);
315 			rxchars = 0;
316 		}
317 		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
318 			uart_write_wakeup(&s->port);
319 
320 	} while (!s->force_end_work &&
321 		 !freezing(current) &&
322 		 ((rx & MAX3100_R) ||
323 		  (!uart_circ_empty(xmit) &&
324 		   !uart_tx_stopped(&s->port))));
325 
326 	if (rxchars > 0)
327 		tty_flip_buffer_push(&s->port.state->port);
328 }
329 
330 static irqreturn_t max3100_irq(int irqno, void *dev_id)
331 {
332 	struct max3100_port *s = dev_id;
333 
334 	dev_dbg(&s->spi->dev, "%s\n", __func__);
335 
336 	max3100_dowork(s);
337 	return IRQ_HANDLED;
338 }
339 
340 static void max3100_enable_ms(struct uart_port *port)
341 {
342 	struct max3100_port *s = container_of(port,
343 					      struct max3100_port,
344 					      port);
345 
346 	if (s->poll_time > 0)
347 		mod_timer(&s->timer, jiffies);
348 	dev_dbg(&s->spi->dev, "%s\n", __func__);
349 }
350 
351 static void max3100_start_tx(struct uart_port *port)
352 {
353 	struct max3100_port *s = container_of(port,
354 					      struct max3100_port,
355 					      port);
356 
357 	dev_dbg(&s->spi->dev, "%s\n", __func__);
358 
359 	max3100_dowork(s);
360 }
361 
362 static void max3100_stop_rx(struct uart_port *port)
363 {
364 	struct max3100_port *s = container_of(port,
365 					      struct max3100_port,
366 					      port);
367 
368 	dev_dbg(&s->spi->dev, "%s\n", __func__);
369 
370 	s->rx_enabled = 0;
371 	spin_lock(&s->conf_lock);
372 	s->conf &= ~MAX3100_RM;
373 	s->conf_commit = 1;
374 	spin_unlock(&s->conf_lock);
375 	max3100_dowork(s);
376 }
377 
378 static unsigned int max3100_tx_empty(struct uart_port *port)
379 {
380 	struct max3100_port *s = container_of(port,
381 					      struct max3100_port,
382 					      port);
383 
384 	dev_dbg(&s->spi->dev, "%s\n", __func__);
385 
386 	/* may not be truly up-to-date */
387 	max3100_dowork(s);
388 	return s->tx_empty;
389 }
390 
391 static unsigned int max3100_get_mctrl(struct uart_port *port)
392 {
393 	struct max3100_port *s = container_of(port,
394 					      struct max3100_port,
395 					      port);
396 
397 	dev_dbg(&s->spi->dev, "%s\n", __func__);
398 
399 	/* may not be truly up-to-date */
400 	max3100_dowork(s);
401 	/* always assert DCD and DSR since these lines are not wired */
402 	return (s->cts ? TIOCM_CTS : 0) | TIOCM_DSR | TIOCM_CAR;
403 }
404 
405 static void max3100_set_mctrl(struct uart_port *port, unsigned int mctrl)
406 {
407 	struct max3100_port *s = container_of(port,
408 					      struct max3100_port,
409 					      port);
410 	int rts;
411 
412 	dev_dbg(&s->spi->dev, "%s\n", __func__);
413 
414 	rts = (mctrl & TIOCM_RTS) > 0;
415 
416 	spin_lock(&s->conf_lock);
417 	if (s->rts != rts) {
418 		s->rts = rts;
419 		s->rts_commit = 1;
420 		max3100_dowork(s);
421 	}
422 	spin_unlock(&s->conf_lock);
423 }
424 
425 static void
426 max3100_set_termios(struct uart_port *port, struct ktermios *termios,
427 		    struct ktermios *old)
428 {
429 	struct max3100_port *s = container_of(port,
430 					      struct max3100_port,
431 					      port);
432 	int baud = 0;
433 	unsigned cflag;
434 	u32 param_new, param_mask, parity = 0;
435 
436 	dev_dbg(&s->spi->dev, "%s\n", __func__);
437 
438 	cflag = termios->c_cflag;
439 	param_mask = 0;
440 
441 	baud = tty_termios_baud_rate(termios);
442 	param_new = s->conf & MAX3100_BAUD;
443 	switch (baud) {
444 	case 300:
445 		if (s->crystal)
446 			baud = s->baud;
447 		else
448 			param_new = 15;
449 		break;
450 	case 600:
451 		param_new = 14 + s->crystal;
452 		break;
453 	case 1200:
454 		param_new = 13 + s->crystal;
455 		break;
456 	case 2400:
457 		param_new = 12 + s->crystal;
458 		break;
459 	case 4800:
460 		param_new = 11 + s->crystal;
461 		break;
462 	case 9600:
463 		param_new = 10 + s->crystal;
464 		break;
465 	case 19200:
466 		param_new = 9 + s->crystal;
467 		break;
468 	case 38400:
469 		param_new = 8 + s->crystal;
470 		break;
471 	case 57600:
472 		param_new = 1 + s->crystal;
473 		break;
474 	case 115200:
475 		param_new = 0 + s->crystal;
476 		break;
477 	case 230400:
478 		if (s->crystal)
479 			param_new = 0;
480 		else
481 			baud = s->baud;
482 		break;
483 	default:
484 		baud = s->baud;
485 	}
486 	tty_termios_encode_baud_rate(termios, baud, baud);
487 	s->baud = baud;
488 	param_mask |= MAX3100_BAUD;
489 
490 	if ((cflag & CSIZE) == CS8) {
491 		param_new &= ~MAX3100_L;
492 		parity &= ~MAX3100_7BIT;
493 	} else {
494 		param_new |= MAX3100_L;
495 		parity |= MAX3100_7BIT;
496 		cflag = (cflag & ~CSIZE) | CS7;
497 	}
498 	param_mask |= MAX3100_L;
499 
500 	if (cflag & CSTOPB)
501 		param_new |= MAX3100_ST;
502 	else
503 		param_new &= ~MAX3100_ST;
504 	param_mask |= MAX3100_ST;
505 
506 	if (cflag & PARENB) {
507 		param_new |= MAX3100_PE;
508 		parity |= MAX3100_PARITY_ON;
509 	} else {
510 		param_new &= ~MAX3100_PE;
511 		parity &= ~MAX3100_PARITY_ON;
512 	}
513 	param_mask |= MAX3100_PE;
514 
515 	if (cflag & PARODD)
516 		parity |= MAX3100_PARITY_ODD;
517 	else
518 		parity &= ~MAX3100_PARITY_ODD;
519 
520 	/* mask termios capabilities we don't support */
521 	cflag &= ~CMSPAR;
522 	termios->c_cflag = cflag;
523 
524 	s->port.ignore_status_mask = 0;
525 	if (termios->c_iflag & IGNPAR)
526 		s->port.ignore_status_mask |=
527 			MAX3100_STATUS_PE | MAX3100_STATUS_FE |
528 			MAX3100_STATUS_OE;
529 
530 	/* we are sending char from a workqueue so enable */
531 	s->port.state->port.low_latency = 1;
532 
533 	if (s->poll_time > 0)
534 		del_timer_sync(&s->timer);
535 
536 	uart_update_timeout(port, termios->c_cflag, baud);
537 
538 	spin_lock(&s->conf_lock);
539 	s->conf = (s->conf & ~param_mask) | (param_new & param_mask);
540 	s->conf_commit = 1;
541 	s->parity = parity;
542 	spin_unlock(&s->conf_lock);
543 	max3100_dowork(s);
544 
545 	if (UART_ENABLE_MS(&s->port, termios->c_cflag))
546 		max3100_enable_ms(&s->port);
547 }
548 
549 static void max3100_shutdown(struct uart_port *port)
550 {
551 	struct max3100_port *s = container_of(port,
552 					      struct max3100_port,
553 					      port);
554 
555 	dev_dbg(&s->spi->dev, "%s\n", __func__);
556 
557 	if (s->suspending)
558 		return;
559 
560 	s->force_end_work = 1;
561 
562 	if (s->poll_time > 0)
563 		del_timer_sync(&s->timer);
564 
565 	if (s->workqueue) {
566 		flush_workqueue(s->workqueue);
567 		destroy_workqueue(s->workqueue);
568 		s->workqueue = NULL;
569 	}
570 	if (s->irq)
571 		free_irq(s->irq, s);
572 
573 	/* set shutdown mode to save power */
574 	if (s->max3100_hw_suspend)
575 		s->max3100_hw_suspend(1);
576 	else  {
577 		u16 tx, rx;
578 
579 		tx = MAX3100_WC | MAX3100_SHDN;
580 		max3100_sr(s, tx, &rx);
581 	}
582 }
583 
584 static int max3100_startup(struct uart_port *port)
585 {
586 	struct max3100_port *s = container_of(port,
587 					      struct max3100_port,
588 					      port);
589 	char b[12];
590 
591 	dev_dbg(&s->spi->dev, "%s\n", __func__);
592 
593 	s->conf = MAX3100_RM;
594 	s->baud = s->crystal ? 230400 : 115200;
595 	s->rx_enabled = 1;
596 
597 	if (s->suspending)
598 		return 0;
599 
600 	s->force_end_work = 0;
601 	s->parity = 0;
602 	s->rts = 0;
603 
604 	sprintf(b, "max3100-%d", s->minor);
605 	s->workqueue = create_freezable_workqueue(b);
606 	if (!s->workqueue) {
607 		dev_warn(&s->spi->dev, "cannot create workqueue\n");
608 		return -EBUSY;
609 	}
610 	INIT_WORK(&s->work, max3100_work);
611 
612 	if (request_irq(s->irq, max3100_irq,
613 			IRQF_TRIGGER_FALLING, "max3100", s) < 0) {
614 		dev_warn(&s->spi->dev, "cannot allocate irq %d\n", s->irq);
615 		s->irq = 0;
616 		destroy_workqueue(s->workqueue);
617 		s->workqueue = NULL;
618 		return -EBUSY;
619 	}
620 
621 	if (s->loopback) {
622 		u16 tx, rx;
623 		tx = 0x4001;
624 		max3100_sr(s, tx, &rx);
625 	}
626 
627 	if (s->max3100_hw_suspend)
628 		s->max3100_hw_suspend(0);
629 	s->conf_commit = 1;
630 	max3100_dowork(s);
631 	/* wait for clock to settle */
632 	msleep(50);
633 
634 	max3100_enable_ms(&s->port);
635 
636 	return 0;
637 }
638 
639 static const char *max3100_type(struct uart_port *port)
640 {
641 	struct max3100_port *s = container_of(port,
642 					      struct max3100_port,
643 					      port);
644 
645 	dev_dbg(&s->spi->dev, "%s\n", __func__);
646 
647 	return s->port.type == PORT_MAX3100 ? "MAX3100" : NULL;
648 }
649 
650 static void max3100_release_port(struct uart_port *port)
651 {
652 	struct max3100_port *s = container_of(port,
653 					      struct max3100_port,
654 					      port);
655 
656 	dev_dbg(&s->spi->dev, "%s\n", __func__);
657 }
658 
659 static void max3100_config_port(struct uart_port *port, int flags)
660 {
661 	struct max3100_port *s = container_of(port,
662 					      struct max3100_port,
663 					      port);
664 
665 	dev_dbg(&s->spi->dev, "%s\n", __func__);
666 
667 	if (flags & UART_CONFIG_TYPE)
668 		s->port.type = PORT_MAX3100;
669 }
670 
671 static int max3100_verify_port(struct uart_port *port,
672 			       struct serial_struct *ser)
673 {
674 	struct max3100_port *s = container_of(port,
675 					      struct max3100_port,
676 					      port);
677 	int ret = -EINVAL;
678 
679 	dev_dbg(&s->spi->dev, "%s\n", __func__);
680 
681 	if (ser->type == PORT_UNKNOWN || ser->type == PORT_MAX3100)
682 		ret = 0;
683 	return ret;
684 }
685 
686 static void max3100_stop_tx(struct uart_port *port)
687 {
688 	struct max3100_port *s = container_of(port,
689 					      struct max3100_port,
690 					      port);
691 
692 	dev_dbg(&s->spi->dev, "%s\n", __func__);
693 }
694 
695 static int max3100_request_port(struct uart_port *port)
696 {
697 	struct max3100_port *s = container_of(port,
698 					      struct max3100_port,
699 					      port);
700 
701 	dev_dbg(&s->spi->dev, "%s\n", __func__);
702 	return 0;
703 }
704 
705 static void max3100_break_ctl(struct uart_port *port, int break_state)
706 {
707 	struct max3100_port *s = container_of(port,
708 					      struct max3100_port,
709 					      port);
710 
711 	dev_dbg(&s->spi->dev, "%s\n", __func__);
712 }
713 
714 static const struct uart_ops max3100_ops = {
715 	.tx_empty	= max3100_tx_empty,
716 	.set_mctrl	= max3100_set_mctrl,
717 	.get_mctrl	= max3100_get_mctrl,
718 	.stop_tx        = max3100_stop_tx,
719 	.start_tx	= max3100_start_tx,
720 	.stop_rx	= max3100_stop_rx,
721 	.enable_ms      = max3100_enable_ms,
722 	.break_ctl      = max3100_break_ctl,
723 	.startup	= max3100_startup,
724 	.shutdown	= max3100_shutdown,
725 	.set_termios	= max3100_set_termios,
726 	.type		= max3100_type,
727 	.release_port   = max3100_release_port,
728 	.request_port   = max3100_request_port,
729 	.config_port	= max3100_config_port,
730 	.verify_port	= max3100_verify_port,
731 };
732 
733 static struct uart_driver max3100_uart_driver = {
734 	.owner          = THIS_MODULE,
735 	.driver_name    = "ttyMAX",
736 	.dev_name       = "ttyMAX",
737 	.major          = MAX3100_MAJOR,
738 	.minor          = MAX3100_MINOR,
739 	.nr             = MAX_MAX3100,
740 };
741 static int uart_driver_registered;
742 
743 static int max3100_probe(struct spi_device *spi)
744 {
745 	int i, retval;
746 	struct plat_max3100 *pdata;
747 	u16 tx, rx;
748 
749 	mutex_lock(&max3100s_lock);
750 
751 	if (!uart_driver_registered) {
752 		uart_driver_registered = 1;
753 		retval = uart_register_driver(&max3100_uart_driver);
754 		if (retval) {
755 			printk(KERN_ERR "Couldn't register max3100 uart driver\n");
756 			mutex_unlock(&max3100s_lock);
757 			return retval;
758 		}
759 	}
760 
761 	for (i = 0; i < MAX_MAX3100; i++)
762 		if (!max3100s[i])
763 			break;
764 	if (i == MAX_MAX3100) {
765 		dev_warn(&spi->dev, "too many MAX3100 chips\n");
766 		mutex_unlock(&max3100s_lock);
767 		return -ENOMEM;
768 	}
769 
770 	max3100s[i] = kzalloc(sizeof(struct max3100_port), GFP_KERNEL);
771 	if (!max3100s[i]) {
772 		dev_warn(&spi->dev,
773 			 "kmalloc for max3100 structure %d failed!\n", i);
774 		mutex_unlock(&max3100s_lock);
775 		return -ENOMEM;
776 	}
777 	max3100s[i]->spi = spi;
778 	max3100s[i]->irq = spi->irq;
779 	spin_lock_init(&max3100s[i]->conf_lock);
780 	spi_set_drvdata(spi, max3100s[i]);
781 	pdata = dev_get_platdata(&spi->dev);
782 	max3100s[i]->crystal = pdata->crystal;
783 	max3100s[i]->loopback = pdata->loopback;
784 	max3100s[i]->poll_time = msecs_to_jiffies(pdata->poll_time);
785 	if (pdata->poll_time > 0 && max3100s[i]->poll_time == 0)
786 		max3100s[i]->poll_time = 1;
787 	max3100s[i]->max3100_hw_suspend = pdata->max3100_hw_suspend;
788 	max3100s[i]->minor = i;
789 	setup_timer(&max3100s[i]->timer, max3100_timeout,
790 		    (unsigned long)max3100s[i]);
791 
792 	dev_dbg(&spi->dev, "%s: adding port %d\n", __func__, i);
793 	max3100s[i]->port.irq = max3100s[i]->irq;
794 	max3100s[i]->port.uartclk = max3100s[i]->crystal ? 3686400 : 1843200;
795 	max3100s[i]->port.fifosize = 16;
796 	max3100s[i]->port.ops = &max3100_ops;
797 	max3100s[i]->port.flags = UPF_SKIP_TEST | UPF_BOOT_AUTOCONF;
798 	max3100s[i]->port.line = i;
799 	max3100s[i]->port.type = PORT_MAX3100;
800 	max3100s[i]->port.dev = &spi->dev;
801 	retval = uart_add_one_port(&max3100_uart_driver, &max3100s[i]->port);
802 	if (retval < 0)
803 		dev_warn(&spi->dev,
804 			 "uart_add_one_port failed for line %d with error %d\n",
805 			 i, retval);
806 
807 	/* set shutdown mode to save power. Will be woken-up on open */
808 	if (max3100s[i]->max3100_hw_suspend)
809 		max3100s[i]->max3100_hw_suspend(1);
810 	else {
811 		tx = MAX3100_WC | MAX3100_SHDN;
812 		max3100_sr(max3100s[i], tx, &rx);
813 	}
814 	mutex_unlock(&max3100s_lock);
815 	return 0;
816 }
817 
818 static int max3100_remove(struct spi_device *spi)
819 {
820 	struct max3100_port *s = spi_get_drvdata(spi);
821 	int i;
822 
823 	mutex_lock(&max3100s_lock);
824 
825 	/* find out the index for the chip we are removing */
826 	for (i = 0; i < MAX_MAX3100; i++)
827 		if (max3100s[i] == s) {
828 			dev_dbg(&spi->dev, "%s: removing port %d\n", __func__, i);
829 			uart_remove_one_port(&max3100_uart_driver, &max3100s[i]->port);
830 			kfree(max3100s[i]);
831 			max3100s[i] = NULL;
832 			break;
833 		}
834 
835 	WARN_ON(i == MAX_MAX3100);
836 
837 	/* check if this is the last chip we have */
838 	for (i = 0; i < MAX_MAX3100; i++)
839 		if (max3100s[i]) {
840 			mutex_unlock(&max3100s_lock);
841 			return 0;
842 		}
843 	pr_debug("removing max3100 driver\n");
844 	uart_unregister_driver(&max3100_uart_driver);
845 
846 	mutex_unlock(&max3100s_lock);
847 	return 0;
848 }
849 
850 #ifdef CONFIG_PM_SLEEP
851 
852 static int max3100_suspend(struct device *dev)
853 {
854 	struct max3100_port *s = dev_get_drvdata(dev);
855 
856 	dev_dbg(&s->spi->dev, "%s\n", __func__);
857 
858 	disable_irq(s->irq);
859 
860 	s->suspending = 1;
861 	uart_suspend_port(&max3100_uart_driver, &s->port);
862 
863 	if (s->max3100_hw_suspend)
864 		s->max3100_hw_suspend(1);
865 	else {
866 		/* no HW suspend, so do SW one */
867 		u16 tx, rx;
868 
869 		tx = MAX3100_WC | MAX3100_SHDN;
870 		max3100_sr(s, tx, &rx);
871 	}
872 	return 0;
873 }
874 
875 static int max3100_resume(struct device *dev)
876 {
877 	struct max3100_port *s = dev_get_drvdata(dev);
878 
879 	dev_dbg(&s->spi->dev, "%s\n", __func__);
880 
881 	if (s->max3100_hw_suspend)
882 		s->max3100_hw_suspend(0);
883 	uart_resume_port(&max3100_uart_driver, &s->port);
884 	s->suspending = 0;
885 
886 	enable_irq(s->irq);
887 
888 	s->conf_commit = 1;
889 	if (s->workqueue)
890 		max3100_dowork(s);
891 
892 	return 0;
893 }
894 
895 static SIMPLE_DEV_PM_OPS(max3100_pm_ops, max3100_suspend, max3100_resume);
896 #define MAX3100_PM_OPS (&max3100_pm_ops)
897 
898 #else
899 #define MAX3100_PM_OPS NULL
900 #endif
901 
902 static struct spi_driver max3100_driver = {
903 	.driver = {
904 		.name		= "max3100",
905 		.pm		= MAX3100_PM_OPS,
906 	},
907 	.probe		= max3100_probe,
908 	.remove		= max3100_remove,
909 };
910 
911 module_spi_driver(max3100_driver);
912 
913 MODULE_DESCRIPTION("MAX3100 driver");
914 MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
915 MODULE_LICENSE("GPL");
916 MODULE_ALIAS("spi:max3100");
917