xref: /openbmc/linux/drivers/tty/serial/sprd_serial.c (revision 7f2e85840871f199057e65232ebde846192ed989)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2012-2015 Spreadtrum Communications Inc.
4  */
5 
6 #if defined(CONFIG_SERIAL_SPRD_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
7 #define SUPPORT_SYSRQ
8 #endif
9 
10 #include <linux/clk.h>
11 #include <linux/console.h>
12 #include <linux/delay.h>
13 #include <linux/io.h>
14 #include <linux/ioport.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 #include <linux/platform_device.h>
19 #include <linux/serial_core.h>
20 #include <linux/serial.h>
21 #include <linux/slab.h>
22 #include <linux/tty.h>
23 #include <linux/tty_flip.h>
24 
25 /* device name */
26 #define UART_NR_MAX		8
27 #define SPRD_TTY_NAME		"ttyS"
28 #define SPRD_FIFO_SIZE		128
29 #define SPRD_DEF_RATE		26000000
30 #define SPRD_BAUD_IO_LIMIT	3000000
31 #define SPRD_TIMEOUT		256000
32 
33 /* the offset of serial registers and BITs for them */
34 /* data registers */
35 #define SPRD_TXD		0x0000
36 #define SPRD_RXD		0x0004
37 
38 /* line status register and its BITs  */
39 #define SPRD_LSR		0x0008
40 #define SPRD_LSR_OE		BIT(4)
41 #define SPRD_LSR_FE		BIT(3)
42 #define SPRD_LSR_PE		BIT(2)
43 #define SPRD_LSR_BI		BIT(7)
44 #define SPRD_LSR_TX_OVER	BIT(15)
45 
46 /* data number in TX and RX fifo */
47 #define SPRD_STS1		0x000C
48 
49 /* interrupt enable register and its BITs */
50 #define SPRD_IEN		0x0010
51 #define SPRD_IEN_RX_FULL	BIT(0)
52 #define SPRD_IEN_TX_EMPTY	BIT(1)
53 #define SPRD_IEN_BREAK_DETECT	BIT(7)
54 #define SPRD_IEN_TIMEOUT	BIT(13)
55 
56 /* interrupt clear register */
57 #define SPRD_ICLR		0x0014
58 #define SPRD_ICLR_TIMEOUT	BIT(13)
59 
60 /* line control register */
61 #define SPRD_LCR		0x0018
62 #define SPRD_LCR_STOP_1BIT	0x10
63 #define SPRD_LCR_STOP_2BIT	0x30
64 #define SPRD_LCR_DATA_LEN	(BIT(2) | BIT(3))
65 #define SPRD_LCR_DATA_LEN5	0x0
66 #define SPRD_LCR_DATA_LEN6	0x4
67 #define SPRD_LCR_DATA_LEN7	0x8
68 #define SPRD_LCR_DATA_LEN8	0xc
69 #define SPRD_LCR_PARITY	(BIT(0) | BIT(1))
70 #define SPRD_LCR_PARITY_EN	0x2
71 #define SPRD_LCR_EVEN_PAR	0x0
72 #define SPRD_LCR_ODD_PAR	0x1
73 
74 /* control register 1 */
75 #define SPRD_CTL1			0x001C
76 #define RX_HW_FLOW_CTL_THLD	BIT(6)
77 #define RX_HW_FLOW_CTL_EN	BIT(7)
78 #define TX_HW_FLOW_CTL_EN	BIT(8)
79 #define RX_TOUT_THLD_DEF	0x3E00
80 #define RX_HFC_THLD_DEF	0x40
81 
82 /* fifo threshold register */
83 #define SPRD_CTL2		0x0020
84 #define THLD_TX_EMPTY	0x40
85 #define THLD_RX_FULL	0x40
86 
87 /* config baud rate register */
88 #define SPRD_CLKD0		0x0024
89 #define SPRD_CLKD1		0x0028
90 
91 /* interrupt mask status register */
92 #define SPRD_IMSR			0x002C
93 #define SPRD_IMSR_RX_FIFO_FULL		BIT(0)
94 #define SPRD_IMSR_TX_FIFO_EMPTY	BIT(1)
95 #define SPRD_IMSR_BREAK_DETECT		BIT(7)
96 #define SPRD_IMSR_TIMEOUT		BIT(13)
97 
98 struct reg_backup {
99 	u32 ien;
100 	u32 ctrl0;
101 	u32 ctrl1;
102 	u32 ctrl2;
103 	u32 clkd0;
104 	u32 clkd1;
105 	u32 dspwait;
106 };
107 
108 struct sprd_uart_port {
109 	struct uart_port port;
110 	struct reg_backup reg_bak;
111 	char name[16];
112 };
113 
114 static struct sprd_uart_port *sprd_port[UART_NR_MAX];
115 static int sprd_ports_num;
116 
117 static inline unsigned int serial_in(struct uart_port *port, int offset)
118 {
119 	return readl_relaxed(port->membase + offset);
120 }
121 
122 static inline void serial_out(struct uart_port *port, int offset, int value)
123 {
124 	writel_relaxed(value, port->membase + offset);
125 }
126 
127 static unsigned int sprd_tx_empty(struct uart_port *port)
128 {
129 	if (serial_in(port, SPRD_STS1) & 0xff00)
130 		return 0;
131 	else
132 		return TIOCSER_TEMT;
133 }
134 
135 static unsigned int sprd_get_mctrl(struct uart_port *port)
136 {
137 	return TIOCM_DSR | TIOCM_CTS;
138 }
139 
140 static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
141 {
142 	/* nothing to do */
143 }
144 
145 static void sprd_stop_tx(struct uart_port *port)
146 {
147 	unsigned int ien, iclr;
148 
149 	iclr = serial_in(port, SPRD_ICLR);
150 	ien = serial_in(port, SPRD_IEN);
151 
152 	iclr |= SPRD_IEN_TX_EMPTY;
153 	ien &= ~SPRD_IEN_TX_EMPTY;
154 
155 	serial_out(port, SPRD_ICLR, iclr);
156 	serial_out(port, SPRD_IEN, ien);
157 }
158 
159 static void sprd_start_tx(struct uart_port *port)
160 {
161 	unsigned int ien;
162 
163 	ien = serial_in(port, SPRD_IEN);
164 	if (!(ien & SPRD_IEN_TX_EMPTY)) {
165 		ien |= SPRD_IEN_TX_EMPTY;
166 		serial_out(port, SPRD_IEN, ien);
167 	}
168 }
169 
170 static void sprd_stop_rx(struct uart_port *port)
171 {
172 	unsigned int ien, iclr;
173 
174 	iclr = serial_in(port, SPRD_ICLR);
175 	ien = serial_in(port, SPRD_IEN);
176 
177 	ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
178 	iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;
179 
180 	serial_out(port, SPRD_IEN, ien);
181 	serial_out(port, SPRD_ICLR, iclr);
182 }
183 
184 /* The Sprd serial does not support this function. */
185 static void sprd_break_ctl(struct uart_port *port, int break_state)
186 {
187 	/* nothing to do */
188 }
189 
190 static int handle_lsr_errors(struct uart_port *port,
191 			     unsigned int *flag,
192 			     unsigned int *lsr)
193 {
194 	int ret = 0;
195 
196 	/* statistics */
197 	if (*lsr & SPRD_LSR_BI) {
198 		*lsr &= ~(SPRD_LSR_FE | SPRD_LSR_PE);
199 		port->icount.brk++;
200 		ret = uart_handle_break(port);
201 		if (ret)
202 			return ret;
203 	} else if (*lsr & SPRD_LSR_PE)
204 		port->icount.parity++;
205 	else if (*lsr & SPRD_LSR_FE)
206 		port->icount.frame++;
207 	if (*lsr & SPRD_LSR_OE)
208 		port->icount.overrun++;
209 
210 	/* mask off conditions which should be ignored */
211 	*lsr &= port->read_status_mask;
212 	if (*lsr & SPRD_LSR_BI)
213 		*flag = TTY_BREAK;
214 	else if (*lsr & SPRD_LSR_PE)
215 		*flag = TTY_PARITY;
216 	else if (*lsr & SPRD_LSR_FE)
217 		*flag = TTY_FRAME;
218 
219 	return ret;
220 }
221 
222 static inline void sprd_rx(struct uart_port *port)
223 {
224 	struct tty_port *tty = &port->state->port;
225 	unsigned int ch, flag, lsr, max_count = SPRD_TIMEOUT;
226 
227 	while ((serial_in(port, SPRD_STS1) & 0x00ff) && max_count--) {
228 		lsr = serial_in(port, SPRD_LSR);
229 		ch = serial_in(port, SPRD_RXD);
230 		flag = TTY_NORMAL;
231 		port->icount.rx++;
232 
233 		if (lsr & (SPRD_LSR_BI | SPRD_LSR_PE |
234 			SPRD_LSR_FE | SPRD_LSR_OE))
235 			if (handle_lsr_errors(port, &lsr, &flag))
236 				continue;
237 		if (uart_handle_sysrq_char(port, ch))
238 			continue;
239 
240 		uart_insert_char(port, lsr, SPRD_LSR_OE, ch, flag);
241 	}
242 
243 	tty_flip_buffer_push(tty);
244 }
245 
246 static inline void sprd_tx(struct uart_port *port)
247 {
248 	struct circ_buf *xmit = &port->state->xmit;
249 	int count;
250 
251 	if (port->x_char) {
252 		serial_out(port, SPRD_TXD, port->x_char);
253 		port->icount.tx++;
254 		port->x_char = 0;
255 		return;
256 	}
257 
258 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
259 		sprd_stop_tx(port);
260 		return;
261 	}
262 
263 	count = THLD_TX_EMPTY;
264 	do {
265 		serial_out(port, SPRD_TXD, xmit->buf[xmit->tail]);
266 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
267 		port->icount.tx++;
268 		if (uart_circ_empty(xmit))
269 			break;
270 	} while (--count > 0);
271 
272 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
273 		uart_write_wakeup(port);
274 
275 	if (uart_circ_empty(xmit))
276 		sprd_stop_tx(port);
277 }
278 
279 /* this handles the interrupt from one port */
280 static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
281 {
282 	struct uart_port *port = dev_id;
283 	unsigned int ims;
284 
285 	spin_lock(&port->lock);
286 
287 	ims = serial_in(port, SPRD_IMSR);
288 
289 	if (!ims) {
290 		spin_unlock(&port->lock);
291 		return IRQ_NONE;
292 	}
293 
294 	if (ims & SPRD_IMSR_TIMEOUT)
295 		serial_out(port, SPRD_ICLR, SPRD_ICLR_TIMEOUT);
296 
297 	if (ims & (SPRD_IMSR_RX_FIFO_FULL |
298 		SPRD_IMSR_BREAK_DETECT | SPRD_IMSR_TIMEOUT))
299 		sprd_rx(port);
300 
301 	if (ims & SPRD_IMSR_TX_FIFO_EMPTY)
302 		sprd_tx(port);
303 
304 	spin_unlock(&port->lock);
305 
306 	return IRQ_HANDLED;
307 }
308 
309 static int sprd_startup(struct uart_port *port)
310 {
311 	int ret = 0;
312 	unsigned int ien, fc;
313 	unsigned int timeout;
314 	struct sprd_uart_port *sp;
315 	unsigned long flags;
316 
317 	serial_out(port, SPRD_CTL2, ((THLD_TX_EMPTY << 8) | THLD_RX_FULL));
318 
319 	/* clear rx fifo */
320 	timeout = SPRD_TIMEOUT;
321 	while (timeout-- && serial_in(port, SPRD_STS1) & 0x00ff)
322 		serial_in(port, SPRD_RXD);
323 
324 	/* clear tx fifo */
325 	timeout = SPRD_TIMEOUT;
326 	while (timeout-- && serial_in(port, SPRD_STS1) & 0xff00)
327 		cpu_relax();
328 
329 	/* clear interrupt */
330 	serial_out(port, SPRD_IEN, 0);
331 	serial_out(port, SPRD_ICLR, ~0);
332 
333 	/* allocate irq */
334 	sp = container_of(port, struct sprd_uart_port, port);
335 	snprintf(sp->name, sizeof(sp->name), "sprd_serial%d", port->line);
336 	ret = devm_request_irq(port->dev, port->irq, sprd_handle_irq,
337 				IRQF_SHARED, sp->name, port);
338 	if (ret) {
339 		dev_err(port->dev, "fail to request serial irq %d, ret=%d\n",
340 			port->irq, ret);
341 		return ret;
342 	}
343 	fc = serial_in(port, SPRD_CTL1);
344 	fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF;
345 	serial_out(port, SPRD_CTL1, fc);
346 
347 	/* enable interrupt */
348 	spin_lock_irqsave(&port->lock, flags);
349 	ien = serial_in(port, SPRD_IEN);
350 	ien |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
351 	serial_out(port, SPRD_IEN, ien);
352 	spin_unlock_irqrestore(&port->lock, flags);
353 
354 	return 0;
355 }
356 
357 static void sprd_shutdown(struct uart_port *port)
358 {
359 	serial_out(port, SPRD_IEN, 0);
360 	serial_out(port, SPRD_ICLR, ~0);
361 	devm_free_irq(port->dev, port->irq, port);
362 }
363 
364 static void sprd_set_termios(struct uart_port *port,
365 				    struct ktermios *termios,
366 				    struct ktermios *old)
367 {
368 	unsigned int baud, quot;
369 	unsigned int lcr = 0, fc;
370 	unsigned long flags;
371 
372 	/* ask the core to calculate the divisor for us */
373 	baud = uart_get_baud_rate(port, termios, old, 0, SPRD_BAUD_IO_LIMIT);
374 
375 	quot = (unsigned int)((port->uartclk + baud / 2) / baud);
376 
377 	/* set data length */
378 	switch (termios->c_cflag & CSIZE) {
379 	case CS5:
380 		lcr |= SPRD_LCR_DATA_LEN5;
381 		break;
382 	case CS6:
383 		lcr |= SPRD_LCR_DATA_LEN6;
384 		break;
385 	case CS7:
386 		lcr |= SPRD_LCR_DATA_LEN7;
387 		break;
388 	case CS8:
389 	default:
390 		lcr |= SPRD_LCR_DATA_LEN8;
391 		break;
392 	}
393 
394 	/* calculate stop bits */
395 	lcr &= ~(SPRD_LCR_STOP_1BIT | SPRD_LCR_STOP_2BIT);
396 	if (termios->c_cflag & CSTOPB)
397 		lcr |= SPRD_LCR_STOP_2BIT;
398 	else
399 		lcr |= SPRD_LCR_STOP_1BIT;
400 
401 	/* calculate parity */
402 	lcr &= ~SPRD_LCR_PARITY;
403 	termios->c_cflag &= ~CMSPAR;	/* no support mark/space */
404 	if (termios->c_cflag & PARENB) {
405 		lcr |= SPRD_LCR_PARITY_EN;
406 		if (termios->c_cflag & PARODD)
407 			lcr |= SPRD_LCR_ODD_PAR;
408 		else
409 			lcr |= SPRD_LCR_EVEN_PAR;
410 	}
411 
412 	spin_lock_irqsave(&port->lock, flags);
413 
414 	/* update the per-port timeout */
415 	uart_update_timeout(port, termios->c_cflag, baud);
416 
417 	port->read_status_mask = SPRD_LSR_OE;
418 	if (termios->c_iflag & INPCK)
419 		port->read_status_mask |= SPRD_LSR_FE | SPRD_LSR_PE;
420 	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
421 		port->read_status_mask |= SPRD_LSR_BI;
422 
423 	/* characters to ignore */
424 	port->ignore_status_mask = 0;
425 	if (termios->c_iflag & IGNPAR)
426 		port->ignore_status_mask |= SPRD_LSR_PE | SPRD_LSR_FE;
427 	if (termios->c_iflag & IGNBRK) {
428 		port->ignore_status_mask |= SPRD_LSR_BI;
429 		/*
430 		 * If we're ignoring parity and break indicators,
431 		 * ignore overruns too (for real raw support).
432 		 */
433 		if (termios->c_iflag & IGNPAR)
434 			port->ignore_status_mask |= SPRD_LSR_OE;
435 	}
436 
437 	/* flow control */
438 	fc = serial_in(port, SPRD_CTL1);
439 	fc &= ~(RX_HW_FLOW_CTL_THLD | RX_HW_FLOW_CTL_EN | TX_HW_FLOW_CTL_EN);
440 	if (termios->c_cflag & CRTSCTS) {
441 		fc |= RX_HW_FLOW_CTL_THLD;
442 		fc |= RX_HW_FLOW_CTL_EN;
443 		fc |= TX_HW_FLOW_CTL_EN;
444 	}
445 
446 	/* clock divider bit0~bit15 */
447 	serial_out(port, SPRD_CLKD0, quot & 0xffff);
448 
449 	/* clock divider bit16~bit20 */
450 	serial_out(port, SPRD_CLKD1, (quot & 0x1f0000) >> 16);
451 	serial_out(port, SPRD_LCR, lcr);
452 	fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF;
453 	serial_out(port, SPRD_CTL1, fc);
454 
455 	spin_unlock_irqrestore(&port->lock, flags);
456 
457 	/* Don't rewrite B0 */
458 	if (tty_termios_baud_rate(termios))
459 		tty_termios_encode_baud_rate(termios, baud, baud);
460 }
461 
462 static const char *sprd_type(struct uart_port *port)
463 {
464 	return "SPX";
465 }
466 
467 static void sprd_release_port(struct uart_port *port)
468 {
469 	/* nothing to do */
470 }
471 
472 static int sprd_request_port(struct uart_port *port)
473 {
474 	return 0;
475 }
476 
477 static void sprd_config_port(struct uart_port *port, int flags)
478 {
479 	if (flags & UART_CONFIG_TYPE)
480 		port->type = PORT_SPRD;
481 }
482 
483 static int sprd_verify_port(struct uart_port *port,
484 				   struct serial_struct *ser)
485 {
486 	if (ser->type != PORT_SPRD)
487 		return -EINVAL;
488 	if (port->irq != ser->irq)
489 		return -EINVAL;
490 	if (port->iotype != ser->io_type)
491 		return -EINVAL;
492 	return 0;
493 }
494 
495 static const struct uart_ops serial_sprd_ops = {
496 	.tx_empty = sprd_tx_empty,
497 	.get_mctrl = sprd_get_mctrl,
498 	.set_mctrl = sprd_set_mctrl,
499 	.stop_tx = sprd_stop_tx,
500 	.start_tx = sprd_start_tx,
501 	.stop_rx = sprd_stop_rx,
502 	.break_ctl = sprd_break_ctl,
503 	.startup = sprd_startup,
504 	.shutdown = sprd_shutdown,
505 	.set_termios = sprd_set_termios,
506 	.type = sprd_type,
507 	.release_port = sprd_release_port,
508 	.request_port = sprd_request_port,
509 	.config_port = sprd_config_port,
510 	.verify_port = sprd_verify_port,
511 };
512 
513 #ifdef CONFIG_SERIAL_SPRD_CONSOLE
514 static void wait_for_xmitr(struct uart_port *port)
515 {
516 	unsigned int status, tmout = 10000;
517 
518 	/* wait up to 10ms for the character(s) to be sent */
519 	do {
520 		status = serial_in(port, SPRD_STS1);
521 		if (--tmout == 0)
522 			break;
523 		udelay(1);
524 	} while (status & 0xff00);
525 }
526 
527 static void sprd_console_putchar(struct uart_port *port, int ch)
528 {
529 	wait_for_xmitr(port);
530 	serial_out(port, SPRD_TXD, ch);
531 }
532 
533 static void sprd_console_write(struct console *co, const char *s,
534 				      unsigned int count)
535 {
536 	struct uart_port *port = &sprd_port[co->index]->port;
537 	int locked = 1;
538 	unsigned long flags;
539 
540 	if (port->sysrq)
541 		locked = 0;
542 	else if (oops_in_progress)
543 		locked = spin_trylock_irqsave(&port->lock, flags);
544 	else
545 		spin_lock_irqsave(&port->lock, flags);
546 
547 	uart_console_write(port, s, count, sprd_console_putchar);
548 
549 	/* wait for transmitter to become empty */
550 	wait_for_xmitr(port);
551 
552 	if (locked)
553 		spin_unlock_irqrestore(&port->lock, flags);
554 }
555 
556 static int __init sprd_console_setup(struct console *co, char *options)
557 {
558 	struct uart_port *port;
559 	int baud = 115200;
560 	int bits = 8;
561 	int parity = 'n';
562 	int flow = 'n';
563 
564 	if (co->index >= UART_NR_MAX || co->index < 0)
565 		co->index = 0;
566 
567 	port = &sprd_port[co->index]->port;
568 	if (port == NULL) {
569 		pr_info("serial port %d not yet initialized\n", co->index);
570 		return -ENODEV;
571 	}
572 	if (options)
573 		uart_parse_options(options, &baud, &parity, &bits, &flow);
574 
575 	return uart_set_options(port, co, baud, parity, bits, flow);
576 }
577 
578 static struct uart_driver sprd_uart_driver;
579 static struct console sprd_console = {
580 	.name = SPRD_TTY_NAME,
581 	.write = sprd_console_write,
582 	.device = uart_console_device,
583 	.setup = sprd_console_setup,
584 	.flags = CON_PRINTBUFFER,
585 	.index = -1,
586 	.data = &sprd_uart_driver,
587 };
588 
589 #define SPRD_CONSOLE	(&sprd_console)
590 
591 /* Support for earlycon */
592 static void sprd_putc(struct uart_port *port, int c)
593 {
594 	unsigned int timeout = SPRD_TIMEOUT;
595 
596 	while (timeout-- &&
597 		   !(readl(port->membase + SPRD_LSR) & SPRD_LSR_TX_OVER))
598 		cpu_relax();
599 
600 	writeb(c, port->membase + SPRD_TXD);
601 }
602 
603 static void sprd_early_write(struct console *con, const char *s,
604 				    unsigned n)
605 {
606 	struct earlycon_device *dev = con->data;
607 
608 	uart_console_write(&dev->port, s, n, sprd_putc);
609 }
610 
611 static int __init sprd_early_console_setup(
612 				struct earlycon_device *device,
613 				const char *opt)
614 {
615 	if (!device->port.membase)
616 		return -ENODEV;
617 
618 	device->con->write = sprd_early_write;
619 	return 0;
620 }
621 OF_EARLYCON_DECLARE(sprd_serial, "sprd,sc9836-uart",
622 		    sprd_early_console_setup);
623 
624 #else /* !CONFIG_SERIAL_SPRD_CONSOLE */
625 #define SPRD_CONSOLE		NULL
626 #endif
627 
628 static struct uart_driver sprd_uart_driver = {
629 	.owner = THIS_MODULE,
630 	.driver_name = "sprd_serial",
631 	.dev_name = SPRD_TTY_NAME,
632 	.major = 0,
633 	.minor = 0,
634 	.nr = UART_NR_MAX,
635 	.cons = SPRD_CONSOLE,
636 };
637 
638 static int sprd_probe_dt_alias(int index, struct device *dev)
639 {
640 	struct device_node *np;
641 	int ret = index;
642 
643 	if (!IS_ENABLED(CONFIG_OF))
644 		return ret;
645 
646 	np = dev->of_node;
647 	if (!np)
648 		return ret;
649 
650 	ret = of_alias_get_id(np, "serial");
651 	if (ret < 0)
652 		ret = index;
653 	else if (ret >= ARRAY_SIZE(sprd_port) || sprd_port[ret] != NULL) {
654 		dev_warn(dev, "requested serial port %d not available.\n", ret);
655 		ret = index;
656 	}
657 
658 	return ret;
659 }
660 
661 static int sprd_remove(struct platform_device *dev)
662 {
663 	struct sprd_uart_port *sup = platform_get_drvdata(dev);
664 
665 	if (sup) {
666 		uart_remove_one_port(&sprd_uart_driver, &sup->port);
667 		sprd_port[sup->port.line] = NULL;
668 		sprd_ports_num--;
669 	}
670 
671 	if (!sprd_ports_num)
672 		uart_unregister_driver(&sprd_uart_driver);
673 
674 	return 0;
675 }
676 
677 static int sprd_probe(struct platform_device *pdev)
678 {
679 	struct resource *res;
680 	struct uart_port *up;
681 	struct clk *clk;
682 	int irq;
683 	int index;
684 	int ret;
685 
686 	for (index = 0; index < ARRAY_SIZE(sprd_port); index++)
687 		if (sprd_port[index] == NULL)
688 			break;
689 
690 	if (index == ARRAY_SIZE(sprd_port))
691 		return -EBUSY;
692 
693 	index = sprd_probe_dt_alias(index, &pdev->dev);
694 
695 	sprd_port[index] = devm_kzalloc(&pdev->dev,
696 		sizeof(*sprd_port[index]), GFP_KERNEL);
697 	if (!sprd_port[index])
698 		return -ENOMEM;
699 
700 	up = &sprd_port[index]->port;
701 	up->dev = &pdev->dev;
702 	up->line = index;
703 	up->type = PORT_SPRD;
704 	up->iotype = UPIO_MEM;
705 	up->uartclk = SPRD_DEF_RATE;
706 	up->fifosize = SPRD_FIFO_SIZE;
707 	up->ops = &serial_sprd_ops;
708 	up->flags = UPF_BOOT_AUTOCONF;
709 
710 	clk = devm_clk_get(&pdev->dev, NULL);
711 	if (!IS_ERR_OR_NULL(clk))
712 		up->uartclk = clk_get_rate(clk);
713 
714 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
715 	if (!res) {
716 		dev_err(&pdev->dev, "not provide mem resource\n");
717 		return -ENODEV;
718 	}
719 	up->mapbase = res->start;
720 	up->membase = devm_ioremap_resource(&pdev->dev, res);
721 	if (IS_ERR(up->membase))
722 		return PTR_ERR(up->membase);
723 
724 	irq = platform_get_irq(pdev, 0);
725 	if (irq < 0) {
726 		dev_err(&pdev->dev, "not provide irq resource: %d\n", irq);
727 		return irq;
728 	}
729 	up->irq = irq;
730 
731 	if (!sprd_ports_num) {
732 		ret = uart_register_driver(&sprd_uart_driver);
733 		if (ret < 0) {
734 			pr_err("Failed to register SPRD-UART driver\n");
735 			return ret;
736 		}
737 	}
738 	sprd_ports_num++;
739 
740 	ret = uart_add_one_port(&sprd_uart_driver, up);
741 	if (ret) {
742 		sprd_port[index] = NULL;
743 		sprd_remove(pdev);
744 	}
745 
746 	platform_set_drvdata(pdev, up);
747 
748 	return ret;
749 }
750 
751 #ifdef CONFIG_PM_SLEEP
752 static int sprd_suspend(struct device *dev)
753 {
754 	struct sprd_uart_port *sup = dev_get_drvdata(dev);
755 
756 	uart_suspend_port(&sprd_uart_driver, &sup->port);
757 
758 	return 0;
759 }
760 
761 static int sprd_resume(struct device *dev)
762 {
763 	struct sprd_uart_port *sup = dev_get_drvdata(dev);
764 
765 	uart_resume_port(&sprd_uart_driver, &sup->port);
766 
767 	return 0;
768 }
769 #endif
770 
771 static SIMPLE_DEV_PM_OPS(sprd_pm_ops, sprd_suspend, sprd_resume);
772 
773 static const struct of_device_id serial_ids[] = {
774 	{.compatible = "sprd,sc9836-uart",},
775 	{}
776 };
777 MODULE_DEVICE_TABLE(of, serial_ids);
778 
779 static struct platform_driver sprd_platform_driver = {
780 	.probe		= sprd_probe,
781 	.remove		= sprd_remove,
782 	.driver		= {
783 		.name	= "sprd_serial",
784 		.of_match_table = of_match_ptr(serial_ids),
785 		.pm	= &sprd_pm_ops,
786 	},
787 };
788 
789 module_platform_driver(sprd_platform_driver);
790 
791 MODULE_LICENSE("GPL v2");
792 MODULE_DESCRIPTION("Spreadtrum SoC serial driver series");
793