summaryrefslogtreecommitdiffstats
path: root/drivers/tty/serial/sprd_serial.c
blob: 594b63331ef40e42fa75a87cde1c139a46014398 (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
/*
 * Copyright (C) 2012-2015 Spreadtrum Communications Inc.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that 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.
 */

#if defined(CONFIG_SERIAL_SPRD_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/clk.h>
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>

/* device name */
#define UART_NR_MAX		8
#define SPRD_TTY_NAME		"ttyS"
#define SPRD_FIFO_SIZE		128
#define SPRD_DEF_RATE		26000000
#define SPRD_BAUD_IO_LIMIT	3000000
#define SPRD_TIMEOUT		256

/* the offset of serial registers and BITs for them */
/* data registers */
#define SPRD_TXD		0x0000
#define SPRD_RXD		0x0004

/* line status register and its BITs  */
#define SPRD_LSR		0x0008
#define SPRD_LSR_OE		BIT(4)
#define SPRD_LSR_FE		BIT(3)
#define SPRD_LSR_PE		BIT(2)
#define SPRD_LSR_BI		BIT(7)
#define SPRD_LSR_TX_OVER	BIT(15)

/* data number in TX and RX fifo */
#define SPRD_STS1		0x000C

/* interrupt enable register and its BITs */
#define SPRD_IEN		0x0010
#define SPRD_IEN_RX_FULL	BIT(0)
#define SPRD_IEN_TX_EMPTY	BIT(1)
#define SPRD_IEN_BREAK_DETECT	BIT(7)
#define SPRD_IEN_TIMEOUT	BIT(13)

/* interrupt clear register */
#define SPRD_ICLR		0x0014

/* line control register */
#define SPRD_LCR		0x0018
#define SPRD_LCR_STOP_1BIT	0x10
#define SPRD_LCR_STOP_2BIT	0x30
#define SPRD_LCR_DATA_LEN	(BIT(2) | BIT(3))
#define SPRD_LCR_DATA_LEN5	0x0
#define SPRD_LCR_DATA_LEN6	0x4
#define SPRD_LCR_DATA_LEN7	0x8
#define SPRD_LCR_DATA_LEN8	0xc
#define SPRD_LCR_PARITY	(BIT(0) | BIT(1))
#define SPRD_LCR_PARITY_EN	0x2
#define SPRD_LCR_EVEN_PAR	0x0
#define SPRD_LCR_ODD_PAR	0x1

/* control register 1 */
#define SPRD_CTL1			0x001C
#define RX_HW_FLOW_CTL_THLD	BIT(6)
#define RX_HW_FLOW_CTL_EN	BIT(7)
#define TX_HW_FLOW_CTL_EN	BIT(8)
#define RX_TOUT_THLD_DEF	0x3E00
#define RX_HFC_THLD_DEF	0x40

/* fifo threshold register */
#define SPRD_CTL2		0x0020
#define THLD_TX_EMPTY	0x40
#define THLD_RX_FULL	0x40

/* config baud rate register */
#define SPRD_CLKD0		0x0024
#define SPRD_CLKD1		0x0028

/* interrupt mask status register */
#define SPRD_IMSR			0x002C
#define SPRD_IMSR_RX_FIFO_FULL		BIT(0)
#define SPRD_IMSR_TX_FIFO_EMPTY	BIT(1)
#define SPRD_IMSR_BREAK_DETECT		BIT(7)
#define SPRD_IMSR_TIMEOUT		BIT(13)

struct reg_backup {
	u32 ien;
	u32 ctrl0;
	u32 ctrl1;
	u32 ctrl2;
	u32 clkd0;
	u32 clkd1;
	u32 dspwait;
};

struct sprd_uart_port {
	struct uart_port port;
	struct reg_backup reg_bak;
	char name[16];
};

static struct sprd_uart_port *sprd_port[UART_NR_MAX];
static int sprd_ports_num;

static inline unsigned int serial_in(struct uart_port *port, int offset)
{
	return readl_relaxed(port->membase + offset);
}

static inline void serial_out(struct uart_port *port, int offset, int value)
{
	writel_relaxed(value, port->membase + offset);
}

static unsigned int sprd_tx_empty(struct uart_port *port)
{
	if (serial_in(port, SPRD_STS1) & 0xff00)
		return 0;
	else
		return TIOCSER_TEMT;
}

static unsigned int sprd_get_mctrl(struct uart_port *port)
{
	return TIOCM_DSR | TIOCM_CTS;
}

static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	/* nothing to do */
}

static void sprd_stop_tx(struct uart_port *port)
{
	unsigned int ien, iclr;

	iclr = serial_in(port, SPRD_ICLR);
	ien = serial_in(port, SPRD_IEN);

	iclr |= SPRD_IEN_TX_EMPTY;
	ien &= ~SPRD_IEN_TX_EMPTY;

	serial_out(port, SPRD_ICLR, iclr);
	serial_out(port, SPRD_IEN, ien);
}

static void sprd_start_tx(struct uart_port *port)
{
	unsigned int ien;

	ien = serial_in(port, SPRD_IEN);
	if (!(ien & SPRD_IEN_TX_EMPTY)) {
		ien |= SPRD_IEN_TX_EMPTY;
		serial_out(port, SPRD_IEN, ien);
	}
}

static void sprd_stop_rx(struct uart_port *port)
{
	unsigned int ien, iclr;

	iclr = serial_in(port, SPRD_ICLR);
	ien = serial_in(port, SPRD_IEN);

	ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
	iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;

	serial_out(port, SPRD_IEN, ien);
	serial_out(port, SPRD_ICLR, iclr);
}

/* The Sprd serial does not support this function. */
static void sprd_break_ctl(struct uart_port *port, int break_state)
{
	/* nothing to do */
}

static int handle_lsr_errors(struct uart_port *port,
			     unsigned int *flag,
			     unsigned int *lsr)
{
	int ret = 0;

	/* statistics */
	if (*lsr & SPRD_LSR_BI) {
		*lsr &= ~(SPRD_LSR_FE | SPRD_LSR_PE);
		port->icount.brk++;
		ret = uart_handle_break(port);
		if (ret)
			return ret;
	} else if (*lsr & SPRD_LSR_PE)
		port->icount.parity++;
	else if (*lsr & SPRD_LSR_FE)
		port->icount.frame++;
	if (*lsr & SPRD_LSR_OE)
		port->icount.overrun++;

	/* mask off conditions which should be ignored */
	*lsr &= port->read_status_mask;
	if (*lsr & SPRD_LSR_BI)
		*flag = TTY_BREAK;
	else if (*lsr & SPRD_LSR_PE)
		*flag = TTY_PARITY;
	else if (*lsr & SPRD_LSR_FE)
		*flag = TTY_FRAME;

	return ret;
}

static inline void sprd_rx(struct uart_port *port)
{
	struct tty_port *tty = &port->state->port;
	unsigned int ch, flag, lsr, max_count = SPRD_TIMEOUT;

	while ((serial_in(port, SPRD_STS1) & 0x00ff) && max_count--) {
		lsr = serial_in(port, SPRD_LSR);
		ch = serial_in(port, SPRD_RXD);
		flag = TTY_NORMAL;
		port->icount.rx++;

		if (lsr & (SPRD_LSR_BI | SPRD_LSR_PE |
			SPRD_LSR_FE | SPRD_LSR_OE))
			if (handle_lsr_errors(port, &lsr, &flag))
				continue;
		if (uart_handle_sysrq_char(port, ch))
			continue;

		uart_insert_char(port, lsr, SPRD_LSR_OE, ch, flag);
	}

	tty_flip_buffer_push(tty);
}

static inline void sprd_tx(struct uart_port *port)
{
	struct circ_buf *xmit = &port->state->xmit;
	int count;

	if (port->x_char) {
		serial_out(port, SPRD_TXD, port->x_char);
		port->icount.tx++;
		port->x_char = 0;
		return;
	}

	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
		sprd_stop_tx(port);
		return;
	}

	count = THLD_TX_EMPTY;
	do {
		serial_out(port, SPRD_TXD, xmit->buf[xmit->tail]);
		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
		port->icount.tx++;
		if (uart_circ_empty(xmit))
			break;
	} while (--count > 0);

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

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

/* this handles the interrupt from one port */
static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
{
	struct uart_port *port = dev_id;
	unsigned int ims;

	spin_lock(&port->lock);

	ims = serial_in(port, SPRD_IMSR);

	if (!ims)
		return IRQ_NONE;

	serial_out(port, SPRD_ICLR, ~0);

	if (ims & (SPRD_IMSR_RX_FIFO_FULL |
		SPRD_IMSR_BREAK_DETECT | SPRD_IMSR_TIMEOUT))
		sprd_rx(port);

	if (ims & SPRD_IMSR_TX_FIFO_EMPTY)
		sprd_tx(port);

	spin_unlock(&port->lock);

	return IRQ_HANDLED;
}

static int sprd_startup(struct uart_port *port)
{
	int ret = 0;
	unsigned int ien, fc;
	unsigned int timeout;
	struct sprd_uart_port *sp;
	unsigned long flags;

	serial_out(port, SPRD_CTL2, ((THLD_TX_EMPTY << 8) | THLD_RX_FULL));

	/* clear rx fifo */
	timeout = SPRD_TIMEOUT;
	while (timeout-- && serial_in(port, SPRD_STS1) & 0x00ff)
		serial_in(port, SPRD_RXD);

	/* clear tx fifo */
	timeout = SPRD_TIMEOUT;
	while (timeout-- && serial_in(port, SPRD_STS1) & 0xff00)
		cpu_relax();

	/* clear interrupt */
	serial_out(port, SPRD_IEN, 0);
	serial_out(port, SPRD_ICLR, ~0);

	/* allocate irq */
	sp = container_of(port, struct sprd_uart_port, port);
	snprintf(sp->name, sizeof(sp->name), "sprd_serial%d", port->line);
	ret = devm_request_irq(port->dev, port->irq, sprd_handle_irq,
				IRQF_SHARED, sp->name, port);
	if (ret) {
		dev_err(port->dev, "fail to request serial irq %d, ret=%d\n",
			port->irq, ret);
		return ret;
	}
	fc = serial_in(port, SPRD_CTL1);
	fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF;
	serial_out(port, SPRD_CTL1, fc);

	/* enable interrupt */
	spin_lock_irqsave(&port->lock, flags);
	ien = serial_in(port, SPRD_IEN);
	ien |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
	serial_out(port, SPRD_IEN, ien);
	spin_unlock_irqrestore(&port->lock, flags);

	return 0;
}

static void sprd_shutdown(struct uart_port *port)
{
	serial_out(port, SPRD_IEN, 0);
	serial_out(port, SPRD_ICLR, ~0);
	devm_free_irq(port->dev, port->irq, port);
}

static void sprd_set_termios(struct uart_port *port,
				    struct ktermios *termios,
				    struct ktermios *old)
{
	unsigned int baud, quot;
	unsigned int lcr = 0, fc;
	unsigned long flags;

	/* ask the core to calculate the divisor for us */
	baud = uart_get_baud_rate(port, termios, old, 0, SPRD_BAUD_IO_LIMIT);

	quot = (unsigned int)((port->uartclk + baud / 2) / baud);

	/* set data length */
	switch (termios->c_cflag & CSIZE) {
	case CS5:
		lcr |= SPRD_LCR_DATA_LEN5;
		break;
	case CS6:
		lcr |= SPRD_LCR_DATA_LEN6;
		break;
	case CS7:
		lcr |= SPRD_LCR_DATA_LEN7;
		break;
	case CS8:
	default:
		lcr |= SPRD_LCR_DATA_LEN8;
		break;
	}

	/* calculate stop bits */
	lcr &= ~(SPRD_LCR_STOP_1BIT | SPRD_LCR_STOP_2BIT);
	if (termios->c_cflag & CSTOPB)
		lcr |= SPRD_LCR_STOP_2BIT;
	else
		lcr |= SPRD_LCR_STOP_1BIT;

	/* calculate parity */
	lcr &= ~SPRD_LCR_PARITY;
	termios->c_cflag &= ~CMSPAR;	/* no support mark/space */
	if (termios->c_cflag & PARENB) {
		lcr |= SPRD_LCR_PARITY_EN;
		if (termios->c_cflag & PARODD)
			lcr |= SPRD_LCR_ODD_PAR;
		else
			lcr |= SPRD_LCR_EVEN_PAR;
	}

	spin_lock_irqsave(&port->lock, flags);

	/* update the per-port timeout */
	uart_update_timeout(port, termios->c_cflag, baud);

	port->read_status_mask = SPRD_LSR_OE;
	if (termios->c_iflag & INPCK)
		port->read_status_mask |= SPRD_LSR_FE | SPRD_LSR_PE;
	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
		port->read_status_mask |= SPRD_LSR_BI;

	/* characters to ignore */
	port->ignore_status_mask = 0;
	if (termios->c_iflag & IGNPAR)
		port->ignore_status_mask |= SPRD_LSR_PE | SPRD_LSR_FE;
	if (termios->c_iflag & IGNBRK) {
		port->ignore_status_mask |= SPRD_LSR_BI;
		/*
		 * If we're ignoring parity and break indicators,
		 * ignore overruns too (for real raw support).
		 */
		if (termios->c_iflag & IGNPAR)
			port->ignore_status_mask |= SPRD_LSR_OE;
	}

	/* flow control */
	fc = serial_in(port, SPRD_CTL1);
	fc &= ~(RX_HW_FLOW_CTL_THLD | RX_HW_FLOW_CTL_EN | TX_HW_FLOW_CTL_EN);
	if (termios->c_cflag & CRTSCTS) {
		fc |= RX_HW_FLOW_CTL_THLD;
		fc |= RX_HW_FLOW_CTL_EN;
		fc |= TX_HW_FLOW_CTL_EN;
	}

	/* clock divider bit0~bit15 */
	serial_out(port, SPRD_CLKD0, quot & 0xffff);

	/* clock divider bit16~bit20 */
	serial_out(port, SPRD_CLKD1, (quot & 0x1f0000) >> 16);
	serial_out(port, SPRD_LCR, lcr);
	fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF;
	serial_out(port, SPRD_CTL1, fc);

	spin_unlock_irqrestore(&port->lock, flags);

	/* Don't rewrite B0 */
	if (tty_termios_baud_rate(termios))
		tty_termios_encode_baud_rate(termios, baud, baud);
}

static const char *sprd_type(struct uart_port *port)
{
	return "SPX";
}

static void sprd_release_port(struct uart_port *port)
{
	/* nothing to do */
}

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

static void sprd_config_port(struct uart_port *port, int flags)
{
	if (flags & UART_CONFIG_TYPE)
		port->type = PORT_SPRD;
}

static int sprd_verify_port(struct uart_port *port,
				   struct serial_struct *ser)
{
	if (ser->type != PORT_SPRD)
		return -EINVAL;
	if (port->irq != ser->irq)
		return -EINVAL;
	return 0;
}

static struct uart_ops serial_sprd_ops = {
	.tx_empty = sprd_tx_empty,
	.get_mctrl = sprd_get_mctrl,
	.set_mctrl = sprd_set_mctrl,
	.stop_tx = sprd_stop_tx,
	.start_tx = sprd_start_tx,
	.stop_rx = sprd_stop_rx,
	.break_ctl = sprd_break_ctl,
	.startup = sprd_startup,
	.shutdown = sprd_shutdown,
	.set_termios = sprd_set_termios,
	.type = sprd_type,
	.release_port = sprd_release_port,
	.request_port = sprd_request_port,
	.config_port = sprd_config_port,
	.verify_port = sprd_verify_port,
};

#ifdef CONFIG_SERIAL_SPRD_CONSOLE
static inline void wait_for_xmitr(struct uart_port *port)
{
	unsigned int status, tmout = 10000;

	/* wait up to 10ms for the character(s) to be sent */
	do {
		status = serial_in(port, SPRD_STS1);
		if (--tmout == 0)
			break;
		udelay(1);
	} while (status & 0xff00);
}

static void sprd_console_putchar(struct uart_port *port, int ch)
{
	wait_for_xmitr(port);
	serial_out(port, SPRD_TXD, ch);
}

static void sprd_console_write(struct console *co, const char *s,
				      unsigned int count)
{
	struct uart_port *port = &sprd_port[co->index]->port;
	int locked = 1;
	unsigned long flags;

	if (port->sysrq)
		locked = 0;
	else if (oops_in_progress)
		locked = spin_trylock_irqsave(&port->lock, flags);
	else
		spin_lock_irqsave(&port->lock, flags);

	uart_console_write(port, s, count, sprd_console_putchar);

	/* wait for transmitter to become empty */
	wait_for_xmitr(port);

	if (locked)
		spin_unlock_irqrestore(&port->lock, flags);
}

static int __init sprd_console_setup(struct console *co, char *options)
{
	struct uart_port *port;
	int baud = 115200;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';

	if (co->index >= UART_NR_MAX || co->index < 0)
		co->index = 0;

	port = &sprd_port[co->index]->port;
	if (port == NULL) {
		pr_info("serial port %d not yet initialized\n", co->index);
		return -ENODEV;
	}
	if (options)
		uart_parse_options(options, &baud, &parity, &bits, &flow);

	return uart_set_options(port, co, baud, parity, bits, flow);
}

static struct uart_driver sprd_uart_driver;
static struct console sprd_console = {
	.name = SPRD_TTY_NAME,
	.write = sprd_console_write,
	.device = uart_console_device,
	.setup = sprd_console_setup,
	.flags = CON_PRINTBUFFER,
	.index = -1,
	.data = &sprd_uart_driver,
};

#define SPRD_CONSOLE	(&sprd_console)

/* Support for earlycon */
static void sprd_putc(struct uart_port *port, int c)
{
	unsigned int timeout = SPRD_TIMEOUT;

	while (timeout-- &&
		   !(readl(port->membase + SPRD_LSR) & SPRD_LSR_TX_OVER))
		cpu_relax();

	writeb(c, port->membase + SPRD_TXD);
}

static void sprd_early_write(struct console *con, const char *s,
				    unsigned n)
{
	struct earlycon_device *dev = con->data;

	uart_console_write(&dev->port, s, n, sprd_putc);
}

static int __init sprd_early_console_setup(
				struct earlycon_device *device,
				const char *opt)
{
	if (!device->port.membase)
		return -ENODEV;

	device->con->write = sprd_early_write;
	return 0;
}

EARLYCON_DECLARE(sprd_serial, sprd_early_console_setup);
OF_EARLYCON_DECLARE(sprd_serial, "sprd,sc9836-uart",
		    sprd_early_console_setup);

#else /* !CONFIG_SERIAL_SPRD_CONSOLE */
#define SPRD_CONSOLE		NULL
#endif

static struct uart_driver sprd_uart_driver = {
	.owner = THIS_MODULE,
	.driver_name = "sprd_serial",
	.dev_name = SPRD_TTY_NAME,
	.major = 0,
	.minor = 0,
	.nr = UART_NR_MAX,
	.cons = SPRD_CONSOLE,
};

static int sprd_probe_dt_alias(int index, struct device *dev)
{
	struct device_node *np;
	int ret = index;

	if (!IS_ENABLED(CONFIG_OF))
		return ret;

	np = dev->of_node;
	if (!np)
		return ret;

	ret = of_alias_get_id(np, "serial");
	if (IS_ERR_VALUE(ret))
		ret = index;
	else if (ret >= ARRAY_SIZE(sprd_port) || sprd_port[ret] != NULL) {
		dev_warn(dev, "requested serial port %d not available.\n", ret);
		ret = index;
	}

	return ret;
}

static int sprd_remove(struct platform_device *dev)
{
	struct sprd_uart_port *sup = platform_get_drvdata(dev);

	if (sup) {
		uart_remove_one_port(&sprd_uart_driver, &sup->port);
		sprd_port[sup->port.line] = NULL;
		sprd_ports_num--;
	}

	if (!sprd_ports_num)
		uart_unregister_driver(&sprd_uart_driver);

	return 0;
}

static int sprd_probe(struct platform_device *pdev)
{
	struct resource *res;
	struct uart_port *up;
	struct clk *clk;
	int irq;
	int index;
	int ret;

	for (index = 0; index < ARRAY_SIZE(sprd_port); index++)
		if (sprd_port[index] == NULL)
			break;

	if (index == ARRAY_SIZE(sprd_port))
		return -EBUSY;

	index = sprd_probe_dt_alias(index, &pdev->dev);

	sprd_port[index] = devm_kzalloc(&pdev->dev,
		sizeof(*sprd_port[index]), GFP_KERNEL);
	if (!sprd_port[index])
		return -ENOMEM;

	up = &sprd_port[index]->port;
	up->dev = &pdev->dev;
	up->line = index;
	up->type = PORT_SPRD;
	up->iotype = SERIAL_IO_PORT;
	up->uartclk = SPRD_DEF_RATE;
	up->fifosize = SPRD_FIFO_SIZE;
	up->ops = &serial_sprd_ops;
	up->flags = UPF_BOOT_AUTOCONF;

	clk = devm_clk_get(&pdev->dev, NULL);
	if (!IS_ERR(clk))
		up->uartclk = clk_get_rate(clk);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
		dev_err(&pdev->dev, "not provide mem resource\n");
		return -ENODEV;
	}
	up->mapbase = res->start;
	up->membase = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(up->membase))
		return PTR_ERR(up->membase);

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
		dev_err(&pdev->dev, "not provide irq resource\n");
		return -ENODEV;
	}
	up->irq = irq;

	if (!sprd_ports_num) {
		ret = uart_register_driver(&sprd_uart_driver);
		if (ret < 0) {
			pr_err("Failed to register SPRD-UART driver\n");
			return ret;
		}
	}
	sprd_ports_num++;

	ret = uart_add_one_port(&sprd_uart_driver, up);
	if (ret) {
		sprd_port[index] = NULL;
		sprd_remove(pdev);
	}

	platform_set_drvdata(pdev, up);

	return ret;
}

static int sprd_suspend(struct device *dev)
{
	struct sprd_uart_port *sup = dev_get_drvdata(dev);

	uart_suspend_port(&sprd_uart_driver, &sup->port);

	return 0;
}

static int sprd_resume(struct device *dev)
{
	struct sprd_uart_port *sup = dev_get_drvdata(dev);

	uart_resume_port(&sprd_uart_driver, &sup->port);

	return 0;
}

static SIMPLE_DEV_PM_OPS(sprd_pm_ops, sprd_suspend, sprd_resume);

static const struct of_device_id serial_ids[] = {
	{.compatible = "sprd,sc9836-uart",},
	{}
};

static struct platform_driver sprd_platform_driver = {
	.probe		= sprd_probe,
	.remove		= sprd_remove,
	.driver		= {
		.name	= "sprd_serial",
		.of_match_table = of_match_ptr(serial_ids),
		.pm	= &sprd_pm_ops,
	},
};

module_platform_driver(sprd_platform_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Spreadtrum SoC serial driver series");