aboutsummaryrefslogtreecommitdiff
path: root/drivers/serial/mrst_max3110.c
blob: f6ad1ecbff79ec9688fbc024a2036f351efff26e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
/*
 *  max3110.c - spi uart protocol driver for Maxim 3110 on Moorestown
 *
 *  Copyright (C) Intel 2008 Feng Tang <feng.tang@intel.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

/*
 * Note:
 * 1. From Max3110 spec, the Rx FIFO has 8 words, while the Tx FIFO only has
 *    1 word. If SPI master controller doesn't support sclk frequency change,
 *    then the char need be sent out one by one with some delay
 *
 * 2. Currently only RX availabe interrrupt is used, no need for waiting TXE
 *    interrupt for a low speed UART device
 */

#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/platform_device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/serial_reg.h>

#include <linux/kthread.h>
#include <linux/delay.h>
#include <asm/atomic.h>
#include <linux/spi/spi.h>
#include <linux/spi/dw_spi.h>

#include "mrst_max3110.h"

#define PR_FMT	"mrst_max3110: "

#define UART_TX_NEEDED 1
#define CON_TX_NEEDED  2
#define BIT_IRQ_PENDING    3

struct uart_max3110 {
	struct uart_port port;
	struct spi_device *spi;
	char *name;

	wait_queue_head_t wq;
	struct task_struct *main_thread;
	struct task_struct *read_thread;
	struct mutex thread_mutex;;

	u32 baud;
	u16 cur_conf;
	u8 clock;
	u8 parity, word_7bits;

	unsigned long uart_flags;

	/* console related */
	struct circ_buf con_xmit;

	/* irq related */
	u16 irq;
};

/* global data structure, may need be removed */
struct uart_max3110 *pmax;
static inline void receive_char(struct uart_max3110 *max, u8 ch);
static void receive_chars(struct uart_max3110 *max,
				unsigned char *str, int len);
static int max3110_read_multi(struct uart_max3110 *max, int len, u8 *buf);
static void max3110_console_receive(struct uart_max3110 *max);

int max3110_write_then_read(struct uart_max3110 *max,
		const u8 *txbuf, u8 *rxbuf, unsigned len, int always_fast)
{
	struct spi_device *spi = max->spi;
	struct spi_message	message;
	struct spi_transfer	x;
	int ret;

	if (!txbuf || !rxbuf)
		return -EINVAL;

	spi_message_init(&message);
	memset(&x, 0, sizeof x);
	x.len = len;
	x.tx_buf = txbuf;
	x.rx_buf = rxbuf;
	spi_message_add_tail(&x, &message);

	if (always_fast)
		x.speed_hz = 3125000;
	else if (max->baud)
		x.speed_hz = max->baud;

	/* Do the i/o */
	ret = spi_sync(spi, &message);
	return ret;
}

/* Write a u16 to the device, and return one u16 read back */
int max3110_out(struct uart_max3110 *max, const u16 out)
{
	u16 tmp;
	int ret;

	ret = max3110_write_then_read(max, (u8 *)&out, (u8 *)&tmp, 2, 1);
	if (ret)
		return ret;

	/* If some valid data is read back */
	if (tmp & MAX3110_READ_DATA_AVAILABLE)
		receive_char(max, (tmp & 0xff));

	return ret;
}

#define MAX_READ_LEN	20
/*
 * This is usually used to read data from SPIC RX FIFO, which doesn't
 * need any delay like flushing character out. It returns how many
 * valide bytes are read back
 */
static int max3110_read_multi(struct uart_max3110 *max, int len, u8 *buf)
{
	u16 out[MAX_READ_LEN], in[MAX_READ_LEN];
	u8 *pbuf, valid_str[MAX_READ_LEN];
	int i, j, bytelen;

	if (len > MAX_READ_LEN) {
		pr_err(PR_FMT "read len %d is too large\n", len);
		return 0;
	}

	bytelen = len * 2;
	memset(out, 0, bytelen);
	memset(in, 0, bytelen);

	if (max3110_write_then_read(max, (u8 *)out, (u8 *)in, bytelen, 1))
		return 0;

	/* If caller don't provide a buffer, then handle received char */
	pbuf = buf ? buf : valid_str;

	for (i = 0, j = 0; i < len; i++) {
		if (in[i] & MAX3110_READ_DATA_AVAILABLE)
			pbuf[j++] = (u8)(in[i] & 0xff);
	}

	if (j && (pbuf == valid_str))
		receive_chars(max, valid_str, j);

	return j;
}

static void serial_m3110_con_putchar(struct uart_port *port, int ch)
{
	struct uart_max3110 *max =
		container_of(port, struct uart_max3110, port);
	struct circ_buf *xmit = &max->con_xmit;

	if (uart_circ_chars_free(xmit)) {
		xmit->buf[xmit->head] = (char)ch;
		xmit->head = (xmit->head + 1) & (PAGE_SIZE - 1);
	}


	if (!test_and_set_bit(CON_TX_NEEDED, &max->uart_flags))
		wake_up_process(max->main_thread);
}

/*
 * Print a string to the serial port trying not to disturb
 * any possible real use of the port...
 *
 *	The console_lock must be held when we get here.
 */
static void serial_m3110_con_write(struct console *co,
				const char *s, unsigned int count)
{
	if (!pmax)
		return;

	uart_console_write(&pmax->port, s, count, serial_m3110_con_putchar);
}

static int __init
serial_m3110_con_setup(struct console *co, char *options)
{
	struct uart_max3110 *max = pmax;
	int baud = 115200;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';

	pr_info(PR_FMT "setting up console\n");

	if (!max) {
		pr_err(PR_FMT "pmax is NULL, return");
		return -ENODEV;
	}

	if (options)
		uart_parse_options(options, &baud, &parity, &bits, &flow);

	return uart_set_options(&max->port, co, baud, parity, bits, flow);
}

static struct tty_driver *serial_m3110_con_device(struct console *co,
							int *index)
{
	struct uart_driver *p = co->data;
	*index = co->index;
	return p->tty_driver;
}

static struct uart_driver serial_m3110_reg;
static struct console serial_m3110_console = {
	.name		= "ttyS",
	.write		= serial_m3110_con_write,
	.device		= serial_m3110_con_device,
	.setup		= serial_m3110_con_setup,
	.flags		= CON_PRINTBUFFER,
	.index		= -1,
	.data		= &serial_m3110_reg,
};

#define MRST_CONSOLE	(&serial_m3110_console)

static unsigned int serial_m3110_tx_empty(struct uart_port *port)
{
	return 1;
}

static void serial_m3110_stop_tx(struct uart_port *port)
{
	return;
}

/* stop_rx will be called in spin_lock env */
static void serial_m3110_stop_rx(struct uart_port *port)
{
	return;
}

#define WORDS_PER_XFER	128
static inline void send_circ_buf(struct uart_max3110 *max,
				struct circ_buf *xmit)
{
	int len, left = 0;
	u16 obuf[WORDS_PER_XFER], ibuf[WORDS_PER_XFER];
	u8 valid_str[WORDS_PER_XFER];
	int i, j;

	while (!uart_circ_empty(xmit)) {
		left = uart_circ_chars_pending(xmit);
		while (left) {
			len = (left >= WORDS_PER_XFER) ? WORDS_PER_XFER : left;

			memset(obuf, 0, len * 2);
			memset(ibuf, 0, len * 2);
			for (i = 0; i < len; i++) {
				obuf[i] = (u8)xmit->buf[xmit->tail] | WD_TAG;
				xmit->tail = (xmit->tail + 1) &
						(UART_XMIT_SIZE - 1);
			}
			max3110_write_then_read(max, (u8 *)obuf,
						(u8 *)ibuf, len * 2, 0);

			for (i = 0, j = 0; i < len; i++) {
				if (ibuf[i] & MAX3110_READ_DATA_AVAILABLE)
					valid_str[j++] = (u8)(ibuf[i] & 0xff);
			}

			if (j)
				receive_chars(max, valid_str, j);

			max->port.icount.tx += len;
			left -= len;
		}
	}
}

static void transmit_char(struct uart_max3110 *max)
{
	struct uart_port *port = &max->port;
	struct circ_buf *xmit = &port->state->xmit;

	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
		return;

	send_circ_buf(max, xmit);

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(port);

	if (uart_circ_empty(xmit))
		serial_m3110_stop_tx(port);
}

/* This will be called by uart_write() and tty_write, can't
 * go to sleep */
static void serial_m3110_start_tx(struct uart_port *port)
{
	struct uart_max3110 *max =
		container_of(port, struct uart_max3110, port);

	if (!test_and_set_bit(UART_TX_NEEDED, &max->uart_flags))
		wake_up_process(max->main_thread);
}

static void receive_chars(struct uart_max3110 *max, unsigned char *str, int len)
{
	struct uart_port *port = &max->port;
	struct tty_struct *tty;
	int usable;

	/* If uart is not opened, just return */
	if (!port->state)
		return;

	tty = port->state->port.tty;
	if (!tty)
		return;	/* receive some char before the tty is opened */

	while (len) {
		usable = tty_buffer_request_room(tty, len);
		if (usable) {
			tty_insert_flip_string(tty, str, usable);
			str += usable;
			port->icount.rx += usable;
			tty_flip_buffer_push(tty);
		}
		len -= usable;
	}
}

static inline void receive_char(struct uart_max3110 *max, u8 ch)
{
	receive_chars(max, &ch, 1);
}

static void max3110_console_receive(struct uart_max3110 *max)
{
	int loop = 1, num, total = 0;
	u8 recv_buf[512], *pbuf;

	pbuf = recv_buf;
	do {
		num = max3110_read_multi(max, 8, pbuf);

		if (num) {
			loop = 10;
			pbuf += num;
			total += num;

			if (total >= 500) {
				receive_chars(max, recv_buf, total);
				pbuf = recv_buf;
				total = 0;
			}
		}
	} while (--loop);

	if (total)
		receive_chars(max, recv_buf, total);
}

static int max3110_main_thread(void *_max)
{
	struct uart_max3110 *max = _max;
	wait_queue_head_t *wq = &max->wq;
	int ret = 0;
	struct circ_buf *xmit = &max->con_xmit;

	init_waitqueue_head(wq);
	pr_info(PR_FMT "start main thread\n");

	do {
		wait_event_interruptible(*wq, max->uart_flags || kthread_should_stop());

		mutex_lock(&max->thread_mutex);

		if (test_and_clear_bit(BIT_IRQ_PENDING, &max->uart_flags))
			max3110_console_receive(max);

		/* first handle console output */
		if (test_and_clear_bit(CON_TX_NEEDED, &max->uart_flags))
			send_circ_buf(max, xmit);

		/* handle uart output */
		if (test_and_clear_bit(UART_TX_NEEDED, &max->uart_flags))
			transmit_char(max);

		mutex_unlock(&max->thread_mutex);

	} while (!kthread_should_stop());

	return ret;
}

#ifdef CONFIG_MRST_MAX3110_IRQ
static irqreturn_t serial_m3110_irq(int irq, void *dev_id)
{
	struct uart_max3110 *max = dev_id;

	/* max3110's irq is a falling edge, not level triggered,
	 * so no need to disable the irq */
	if (!test_and_set_bit(BIT_IRQ_PENDING, &max->uart_flags))
		wake_up_process(max->main_thread);

	return IRQ_HANDLED;
}
#else
/* if don't use RX IRQ, then need a thread to polling read */
static int max3110_read_thread(void *_max)
{
	struct uart_max3110 *max = _max;

	pr_info(PR_FMT "start read thread\n");
	do {
		mutex_lock(&max->thread_mutex);
		max3110_console_receive(max);
		mutex_unlock(&max->thread_mutex);

		set_current_state(TASK_INTERRUPTIBLE);
		schedule_timeout(HZ / 20);
	} while (!kthread_should_stop());

	return 0;
}
#endif

static int serial_m3110_startup(struct uart_port *port)
{
	struct uart_max3110 *max =
		container_of(port, struct uart_max3110, port);
	u16 config = 0;
	int ret = 0;

	if (port->line != 0)
		pr_err(PR_FMT "uart port startup failed\n");

	/* firstly disable all IRQ and config it to 115200, 8n1 */
	config = WC_TAG | WC_FIFO_ENABLE
			| WC_1_STOPBITS
			| WC_8BIT_WORD
			| WC_BAUD_DR2;
	ret = max3110_out(max, config);

	/* as we use thread to handle tx/rx, need set low latency */
	port->state->port.tty->low_latency = 1;

#ifdef CONFIG_MRST_MAX3110_IRQ
	ret = request_irq(max->irq, serial_m3110_irq,
				IRQ_TYPE_EDGE_FALLING, "max3110", max);
	if (ret)
		return ret;

	/* enable RX IRQ only */
	config |= WC_RXA_IRQ_ENABLE;
	max3110_out(max, config);
#else
	/* if IRQ is disabled, start a read thread for input data */
	max->read_thread =
		kthread_run(max3110_read_thread, max, "max3110_read");
#endif

	max->cur_conf = config;
	return 0;
}

static void serial_m3110_shutdown(struct uart_port *port)
{
	struct uart_max3110 *max =
		container_of(port, struct uart_max3110, port);
	u16 config;

	if (max->read_thread) {
		kthread_stop(max->read_thread);
		max->read_thread = NULL;
	}

#ifdef CONFIG_MRST_MAX3110_IRQ
	free_irq(max->irq, max);
#endif

	/* Disable interrupts from this port */
	config = WC_TAG | WC_SW_SHDI;
	max3110_out(max, config);
}

static void serial_m3110_release_port(struct uart_port *port)
{
}

static int serial_m3110_request_port(struct uart_port *port)
{
	return 0;
}

static void serial_m3110_config_port(struct uart_port *port, int flags)
{
	/* give it fake type */
	port->type = PORT_PXA;
}

static int
serial_m3110_verify_port(struct uart_port *port, struct serial_struct *ser)
{
	/* we don't want the core code to modify any port params */
	return -EINVAL;
}


static const char *serial_m3110_type(struct uart_port *port)
{
	struct uart_max3110 *max =
		container_of(port, struct uart_max3110, port);
	return max->name;
}

static void
serial_m3110_set_termios(struct uart_port *port, struct ktermios *termios,
		       struct ktermios *old)
{
	struct uart_max3110 *max =
		container_of(port, struct uart_max3110, port);
	unsigned char cval;
	unsigned int baud, parity = 0;
	int clk_div = -1;
	u16 new_conf = max->cur_conf;

	switch (termios->c_cflag & CSIZE) {
	case CS7:
		cval = UART_LCR_WLEN7;
		new_conf |= WC_7BIT_WORD;
		break;
	default:
	case CS8:
		cval = UART_LCR_WLEN8;
		new_conf |= WC_8BIT_WORD;
		break;
	}

	baud = uart_get_baud_rate(port, termios, old, 0, 230400);

	/* first calc the div for 1.8MHZ clock case */
	switch (baud) {
	case 300:
		clk_div = WC_BAUD_DR384;
		break;
	case 600:
		clk_div = WC_BAUD_DR192;
		break;
	case 1200:
		clk_div = WC_BAUD_DR96;
		break;
	case 2400:
		clk_div = WC_BAUD_DR48;
		break;
	case 4800:
		clk_div = WC_BAUD_DR24;
		break;
	case 9600:
		clk_div = WC_BAUD_DR12;
		break;
	case 19200:
		clk_div = WC_BAUD_DR6;
		break;
	case 38400:
		clk_div = WC_BAUD_DR3;
		break;
	case 57600:
		clk_div = WC_BAUD_DR2;
		break;
	case 115200:
		clk_div = WC_BAUD_DR1;
		break;
	case 230400:
		if (max->clock & MAX3110_HIGH_CLK)
			break;
	default:
		/* pick the previous baud rate */
		baud = max->baud;
		clk_div = max->cur_conf & WC_BAUD_DIV_MASK;
		tty_termios_encode_baud_rate(termios, baud, baud);
	}

	if (max->clock & MAX3110_HIGH_CLK) {
		clk_div += 1;
		/* high clk version max3110 doesn't support B300 */
		if (baud == 300)
			baud = 600;
		if (baud == 230400)
			clk_div = WC_BAUD_DR1;
		tty_termios_encode_baud_rate(termios, baud, baud);
	}

	new_conf = (new_conf & ~WC_BAUD_DIV_MASK) | clk_div;
	if (termios->c_cflag & CSTOPB)
		new_conf |= WC_2_STOPBITS;
	else
		new_conf &= ~WC_2_STOPBITS;

	if (termios->c_cflag & PARENB) {
		new_conf |= WC_PARITY_ENABLE;
		parity |= UART_LCR_PARITY;
	} else
		new_conf &= ~WC_PARITY_ENABLE;

	if (!(termios->c_cflag & PARODD))
		parity |= UART_LCR_EPAR;
	max->parity = parity;

	uart_update_timeout(port, termios->c_cflag, baud);

	new_conf |= WC_TAG;
	if (new_conf != max->cur_conf) {
		max3110_out(max, new_conf);
		max->cur_conf = new_conf;
		max->baud = baud;
	}
}

/* don't handle hw handshaking */
static unsigned int serial_m3110_get_mctrl(struct uart_port *port)
{
	return TIOCM_DSR | TIOCM_CAR | TIOCM_DSR;
}

static void serial_m3110_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
}

static void serial_m3110_break_ctl(struct uart_port *port, int break_state)
{
}

static void serial_m3110_pm(struct uart_port *port, unsigned int state,
			unsigned int oldstate)
{
}

static void serial_m3110_enable_ms(struct uart_port *port)
{
}

struct uart_ops serial_m3110_ops = {
	.tx_empty	= serial_m3110_tx_empty,
	.set_mctrl	= serial_m3110_set_mctrl,
	.get_mctrl	= serial_m3110_get_mctrl,
	.stop_tx	= serial_m3110_stop_tx,
	.start_tx	= serial_m3110_start_tx,
	.stop_rx	= serial_m3110_stop_rx,
	.enable_ms	= serial_m3110_enable_ms,
	.break_ctl	= serial_m3110_break_ctl,
	.startup	= serial_m3110_startup,
	.shutdown	= serial_m3110_shutdown,
	.set_termios	= serial_m3110_set_termios,	/* must have */
	.pm		= serial_m3110_pm,
	.type		= serial_m3110_type,
	.release_port	= serial_m3110_release_port,
	.request_port	= serial_m3110_request_port,
	.config_port	= serial_m3110_config_port,
	.verify_port	= serial_m3110_verify_port,
};

static struct uart_driver serial_m3110_reg = {
	.owner		= THIS_MODULE,
	.driver_name	= "MRST serial",
	.dev_name	= "ttyS",
	.major		= TTY_MAJOR,
	.minor		= 64,
	.nr		= 1,
	.cons		= MRST_CONSOLE,
};

static int serial_m3110_suspend(struct spi_device *spi, pm_message_t state)
{
	return 0;
}

static int serial_m3110_resume(struct spi_device *spi)
{
	return 0;
}

static struct dw_spi_chip spi0_uart = {
	.poll_mode = 1,
	.enable_dma = 0,
	.type = SPI_FRF_SPI,
};

static int serial_m3110_probe(struct spi_device *spi)
{
	struct uart_max3110 *max;
	int ret;
	unsigned char *buffer;
	u16 res;
	max = kzalloc(sizeof(*max), GFP_KERNEL);
	if (!max)
		return -ENOMEM;

	/* set spi info */
	spi->mode = SPI_MODE_0;
	spi->bits_per_word = 16;
	max->clock = MAX3110_HIGH_CLK;
	spi->controller_data = &spi0_uart;

	spi_setup(spi);

	max->port.type = PORT_PXA;	/* need apply for a max3110 type */
	max->port.fifosize = 2;		/* only have 16b buffer */
	max->port.ops = &serial_m3110_ops;
	max->port.line = 0;
	max->port.dev = &spi->dev;
	max->port.uartclk = 115200;

	max->spi = spi;
	max->name = spi->modalias;	/* use spi name as the name */
	max->irq = (u16)spi->irq;

	mutex_init(&max->thread_mutex);

	max->word_7bits = 0;
	max->parity = 0;
	max->baud = 0;

	max->cur_conf = 0;
	max->uart_flags = 0;

	/* Check if reading configuration register returns something sane */

	res = RC_TAG;
	ret = max3110_write_then_read(max, (u8 *)&res, (u8 *)&res, 2, 0);
	if (ret < 0 || res == 0 || res == 0xffff) {
		printk(KERN_ERR "MAX3111 deemed not present (conf reg %04x)",
									res);
		ret = -ENODEV;
		goto err_get_page;
	}
	buffer = (unsigned char *)__get_free_page(GFP_KERNEL);
	if (!buffer) {
		ret = -ENOMEM;
		goto err_get_page;
	}
	max->con_xmit.buf = (unsigned char *)buffer;
	max->con_xmit.head = max->con_xmit.tail = 0;

	max->main_thread = kthread_run(max3110_main_thread,
					max, "max3110_main");
	if (IS_ERR(max->main_thread)) {
		ret = PTR_ERR(max->main_thread);
		goto err_kthread;
	}

	pmax = max;
	/* give membase a psudo value to pass serial_core's check */
	max->port.membase = (void *)0xff110000;
	uart_add_one_port(&serial_m3110_reg, &max->port);

	return 0;

err_kthread:
	free_page((unsigned long)buffer);
err_get_page:
	pmax = NULL;
	kfree(max);
	return ret;
}

static int max3110_remove(struct spi_device *dev)
{
	struct uart_max3110 *max = pmax;

	if (!pmax)
		return 0;

	pmax = NULL;
	uart_remove_one_port(&serial_m3110_reg, &max->port);

	free_page((unsigned long)max->con_xmit.buf);

	if (max->main_thread)
		kthread_stop(max->main_thread);

	kfree(max);
	return 0;
}

static struct spi_driver uart_max3110_driver = {
	.driver = {
			.name	= "spi_max3111",
			.bus	= &spi_bus_type,
			.owner	= THIS_MODULE,
	},
	.probe		= serial_m3110_probe,
	.remove		= __devexit_p(max3110_remove),
	.suspend	= serial_m3110_suspend,
	.resume		= serial_m3110_resume,
};


int __init serial_m3110_init(void)
{
	int ret = 0;

	ret = uart_register_driver(&serial_m3110_reg);
	if (ret)
		return ret;

	ret = spi_register_driver(&uart_max3110_driver);
	if (ret)
		uart_unregister_driver(&serial_m3110_reg);

	return ret;
}

void __exit serial_m3110_exit(void)
{
	spi_unregister_driver(&uart_max3110_driver);
	uart_unregister_driver(&serial_m3110_reg);
}

module_init(serial_m3110_init);
module_exit(serial_m3110_exit);

MODULE_LICENSE("GPL");
MODULE_ALIAS("max3110-uart");