xref: /openbmc/linux/drivers/tty/serial/sprd_serial.c (revision 367e5927)
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 #define SPRD_RX_FIFO_CNT_MASK	GENMASK(7, 0)
49 #define SPRD_TX_FIFO_CNT_MASK	GENMASK(15, 8)
50 
51 /* interrupt enable register and its BITs */
52 #define SPRD_IEN		0x0010
53 #define SPRD_IEN_RX_FULL	BIT(0)
54 #define SPRD_IEN_TX_EMPTY	BIT(1)
55 #define SPRD_IEN_BREAK_DETECT	BIT(7)
56 #define SPRD_IEN_TIMEOUT	BIT(13)
57 
58 /* interrupt clear register */
59 #define SPRD_ICLR		0x0014
60 #define SPRD_ICLR_TIMEOUT	BIT(13)
61 
62 /* line control register */
63 #define SPRD_LCR		0x0018
64 #define SPRD_LCR_STOP_1BIT	0x10
65 #define SPRD_LCR_STOP_2BIT	0x30
66 #define SPRD_LCR_DATA_LEN	(BIT(2) | BIT(3))
67 #define SPRD_LCR_DATA_LEN5	0x0
68 #define SPRD_LCR_DATA_LEN6	0x4
69 #define SPRD_LCR_DATA_LEN7	0x8
70 #define SPRD_LCR_DATA_LEN8	0xc
71 #define SPRD_LCR_PARITY		(BIT(0) | BIT(1))
72 #define SPRD_LCR_PARITY_EN	0x2
73 #define SPRD_LCR_EVEN_PAR	0x0
74 #define SPRD_LCR_ODD_PAR	0x1
75 
76 /* control register 1 */
77 #define SPRD_CTL1		0x001C
78 #define RX_HW_FLOW_CTL_THLD	BIT(6)
79 #define RX_HW_FLOW_CTL_EN	BIT(7)
80 #define TX_HW_FLOW_CTL_EN	BIT(8)
81 #define RX_TOUT_THLD_DEF	0x3E00
82 #define RX_HFC_THLD_DEF		0x40
83 
84 /* fifo threshold register */
85 #define SPRD_CTL2		0x0020
86 #define THLD_TX_EMPTY		0x40
87 #define THLD_TX_EMPTY_SHIFT	8
88 #define THLD_RX_FULL		0x40
89 
90 /* config baud rate register */
91 #define SPRD_CLKD0		0x0024
92 #define SPRD_CLKD0_MASK		GENMASK(15, 0)
93 #define SPRD_CLKD1		0x0028
94 #define SPRD_CLKD1_MASK		GENMASK(20, 16)
95 #define SPRD_CLKD1_SHIFT	16
96 
97 /* interrupt mask status register */
98 #define SPRD_IMSR		0x002C
99 #define SPRD_IMSR_RX_FIFO_FULL	BIT(0)
100 #define SPRD_IMSR_TX_FIFO_EMPTY	BIT(1)
101 #define SPRD_IMSR_BREAK_DETECT	BIT(7)
102 #define SPRD_IMSR_TIMEOUT	BIT(13)
103 
104 struct sprd_uart_port {
105 	struct uart_port port;
106 	char name[16];
107 };
108 
109 static struct sprd_uart_port *sprd_port[UART_NR_MAX];
110 static int sprd_ports_num;
111 
112 static inline unsigned int serial_in(struct uart_port *port,
113 				     unsigned int offset)
114 {
115 	return readl_relaxed(port->membase + offset);
116 }
117 
118 static inline void serial_out(struct uart_port *port, unsigned int offset,
119 			      int value)
120 {
121 	writel_relaxed(value, port->membase + offset);
122 }
123 
124 static unsigned int sprd_tx_empty(struct uart_port *port)
125 {
126 	if (serial_in(port, SPRD_STS1) & SPRD_TX_FIFO_CNT_MASK)
127 		return 0;
128 	else
129 		return TIOCSER_TEMT;
130 }
131 
132 static unsigned int sprd_get_mctrl(struct uart_port *port)
133 {
134 	return TIOCM_DSR | TIOCM_CTS;
135 }
136 
137 static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
138 {
139 	/* nothing to do */
140 }
141 
142 static void sprd_stop_tx(struct uart_port *port)
143 {
144 	unsigned int ien, iclr;
145 
146 	iclr = serial_in(port, SPRD_ICLR);
147 	ien = serial_in(port, SPRD_IEN);
148 
149 	iclr |= SPRD_IEN_TX_EMPTY;
150 	ien &= ~SPRD_IEN_TX_EMPTY;
151 
152 	serial_out(port, SPRD_ICLR, iclr);
153 	serial_out(port, SPRD_IEN, ien);
154 }
155 
156 static void sprd_start_tx(struct uart_port *port)
157 {
158 	unsigned int ien;
159 
160 	ien = serial_in(port, SPRD_IEN);
161 	if (!(ien & SPRD_IEN_TX_EMPTY)) {
162 		ien |= SPRD_IEN_TX_EMPTY;
163 		serial_out(port, SPRD_IEN, ien);
164 	}
165 }
166 
167 static void sprd_stop_rx(struct uart_port *port)
168 {
169 	unsigned int ien, iclr;
170 
171 	iclr = serial_in(port, SPRD_ICLR);
172 	ien = serial_in(port, SPRD_IEN);
173 
174 	ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
175 	iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;
176 
177 	serial_out(port, SPRD_IEN, ien);
178 	serial_out(port, SPRD_ICLR, iclr);
179 }
180 
181 /* The Sprd serial does not support this function. */
182 static void sprd_break_ctl(struct uart_port *port, int break_state)
183 {
184 	/* nothing to do */
185 }
186 
187 static int handle_lsr_errors(struct uart_port *port,
188 			     unsigned int *flag,
189 			     unsigned int *lsr)
190 {
191 	int ret = 0;
192 
193 	/* statistics */
194 	if (*lsr & SPRD_LSR_BI) {
195 		*lsr &= ~(SPRD_LSR_FE | SPRD_LSR_PE);
196 		port->icount.brk++;
197 		ret = uart_handle_break(port);
198 		if (ret)
199 			return ret;
200 	} else if (*lsr & SPRD_LSR_PE)
201 		port->icount.parity++;
202 	else if (*lsr & SPRD_LSR_FE)
203 		port->icount.frame++;
204 	if (*lsr & SPRD_LSR_OE)
205 		port->icount.overrun++;
206 
207 	/* mask off conditions which should be ignored */
208 	*lsr &= port->read_status_mask;
209 	if (*lsr & SPRD_LSR_BI)
210 		*flag = TTY_BREAK;
211 	else if (*lsr & SPRD_LSR_PE)
212 		*flag = TTY_PARITY;
213 	else if (*lsr & SPRD_LSR_FE)
214 		*flag = TTY_FRAME;
215 
216 	return ret;
217 }
218 
219 static inline void sprd_rx(struct uart_port *port)
220 {
221 	struct tty_port *tty = &port->state->port;
222 	unsigned int ch, flag, lsr, max_count = SPRD_TIMEOUT;
223 
224 	while ((serial_in(port, SPRD_STS1) & SPRD_RX_FIFO_CNT_MASK) &&
225 	       max_count--) {
226 		lsr = serial_in(port, SPRD_LSR);
227 		ch = serial_in(port, SPRD_RXD);
228 		flag = TTY_NORMAL;
229 		port->icount.rx++;
230 
231 		if (lsr & (SPRD_LSR_BI | SPRD_LSR_PE |
232 			   SPRD_LSR_FE | SPRD_LSR_OE))
233 			if (handle_lsr_errors(port, &lsr, &flag))
234 				continue;
235 		if (uart_handle_sysrq_char(port, ch))
236 			continue;
237 
238 		uart_insert_char(port, lsr, SPRD_LSR_OE, ch, flag);
239 	}
240 
241 	tty_flip_buffer_push(tty);
242 }
243 
244 static inline void sprd_tx(struct uart_port *port)
245 {
246 	struct circ_buf *xmit = &port->state->xmit;
247 	int count;
248 
249 	if (port->x_char) {
250 		serial_out(port, SPRD_TXD, port->x_char);
251 		port->icount.tx++;
252 		port->x_char = 0;
253 		return;
254 	}
255 
256 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
257 		sprd_stop_tx(port);
258 		return;
259 	}
260 
261 	count = THLD_TX_EMPTY;
262 	do {
263 		serial_out(port, SPRD_TXD, xmit->buf[xmit->tail]);
264 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
265 		port->icount.tx++;
266 		if (uart_circ_empty(xmit))
267 			break;
268 	} while (--count > 0);
269 
270 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
271 		uart_write_wakeup(port);
272 
273 	if (uart_circ_empty(xmit))
274 		sprd_stop_tx(port);
275 }
276 
277 /* this handles the interrupt from one port */
278 static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
279 {
280 	struct uart_port *port = dev_id;
281 	unsigned int ims;
282 
283 	spin_lock(&port->lock);
284 
285 	ims = serial_in(port, SPRD_IMSR);
286 
287 	if (!ims) {
288 		spin_unlock(&port->lock);
289 		return IRQ_NONE;
290 	}
291 
292 	if (ims & SPRD_IMSR_TIMEOUT)
293 		serial_out(port, SPRD_ICLR, SPRD_ICLR_TIMEOUT);
294 
295 	if (ims & (SPRD_IMSR_RX_FIFO_FULL | SPRD_IMSR_BREAK_DETECT |
296 		   SPRD_IMSR_TIMEOUT))
297 		sprd_rx(port);
298 
299 	if (ims & SPRD_IMSR_TX_FIFO_EMPTY)
300 		sprd_tx(port);
301 
302 	spin_unlock(&port->lock);
303 
304 	return IRQ_HANDLED;
305 }
306 
307 static int sprd_startup(struct uart_port *port)
308 {
309 	int ret = 0;
310 	unsigned int ien, fc;
311 	unsigned int timeout;
312 	struct sprd_uart_port *sp;
313 	unsigned long flags;
314 
315 	serial_out(port, SPRD_CTL2,
316 		   THLD_TX_EMPTY << THLD_TX_EMPTY_SHIFT | THLD_RX_FULL);
317 
318 	/* clear rx fifo */
319 	timeout = SPRD_TIMEOUT;
320 	while (timeout-- && serial_in(port, SPRD_STS1) & SPRD_RX_FIFO_CNT_MASK)
321 		serial_in(port, SPRD_RXD);
322 
323 	/* clear tx fifo */
324 	timeout = SPRD_TIMEOUT;
325 	while (timeout-- && serial_in(port, SPRD_STS1) & SPRD_TX_FIFO_CNT_MASK)
326 		cpu_relax();
327 
328 	/* clear interrupt */
329 	serial_out(port, SPRD_IEN, 0);
330 	serial_out(port, SPRD_ICLR, ~0);
331 
332 	/* allocate irq */
333 	sp = container_of(port, struct sprd_uart_port, port);
334 	snprintf(sp->name, sizeof(sp->name), "sprd_serial%d", port->line);
335 	ret = devm_request_irq(port->dev, port->irq, sprd_handle_irq,
336 			       IRQF_SHARED, sp->name, port);
337 	if (ret) {
338 		dev_err(port->dev, "fail to request serial irq %d, ret=%d\n",
339 			port->irq, ret);
340 		return ret;
341 	}
342 	fc = serial_in(port, SPRD_CTL1);
343 	fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF;
344 	serial_out(port, SPRD_CTL1, fc);
345 
346 	/* enable interrupt */
347 	spin_lock_irqsave(&port->lock, flags);
348 	ien = serial_in(port, SPRD_IEN);
349 	ien |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
350 	serial_out(port, SPRD_IEN, ien);
351 	spin_unlock_irqrestore(&port->lock, flags);
352 
353 	return 0;
354 }
355 
356 static void sprd_shutdown(struct uart_port *port)
357 {
358 	serial_out(port, SPRD_IEN, 0);
359 	serial_out(port, SPRD_ICLR, ~0);
360 	devm_free_irq(port->dev, port->irq, port);
361 }
362 
363 static void sprd_set_termios(struct uart_port *port,
364 			     struct ktermios *termios,
365 			     struct ktermios *old)
366 {
367 	unsigned int baud, quot;
368 	unsigned int lcr = 0, fc;
369 	unsigned long flags;
370 
371 	/* ask the core to calculate the divisor for us */
372 	baud = uart_get_baud_rate(port, termios, old, 0, SPRD_BAUD_IO_LIMIT);
373 
374 	quot = port->uartclk / baud;
375 
376 	/* set data length */
377 	switch (termios->c_cflag & CSIZE) {
378 	case CS5:
379 		lcr |= SPRD_LCR_DATA_LEN5;
380 		break;
381 	case CS6:
382 		lcr |= SPRD_LCR_DATA_LEN6;
383 		break;
384 	case CS7:
385 		lcr |= SPRD_LCR_DATA_LEN7;
386 		break;
387 	case CS8:
388 	default:
389 		lcr |= SPRD_LCR_DATA_LEN8;
390 		break;
391 	}
392 
393 	/* calculate stop bits */
394 	lcr &= ~(SPRD_LCR_STOP_1BIT | SPRD_LCR_STOP_2BIT);
395 	if (termios->c_cflag & CSTOPB)
396 		lcr |= SPRD_LCR_STOP_2BIT;
397 	else
398 		lcr |= SPRD_LCR_STOP_1BIT;
399 
400 	/* calculate parity */
401 	lcr &= ~SPRD_LCR_PARITY;
402 	termios->c_cflag &= ~CMSPAR;	/* no support mark/space */
403 	if (termios->c_cflag & PARENB) {
404 		lcr |= SPRD_LCR_PARITY_EN;
405 		if (termios->c_cflag & PARODD)
406 			lcr |= SPRD_LCR_ODD_PAR;
407 		else
408 			lcr |= SPRD_LCR_EVEN_PAR;
409 	}
410 
411 	spin_lock_irqsave(&port->lock, flags);
412 
413 	/* update the per-port timeout */
414 	uart_update_timeout(port, termios->c_cflag, baud);
415 
416 	port->read_status_mask = SPRD_LSR_OE;
417 	if (termios->c_iflag & INPCK)
418 		port->read_status_mask |= SPRD_LSR_FE | SPRD_LSR_PE;
419 	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
420 		port->read_status_mask |= SPRD_LSR_BI;
421 
422 	/* characters to ignore */
423 	port->ignore_status_mask = 0;
424 	if (termios->c_iflag & IGNPAR)
425 		port->ignore_status_mask |= SPRD_LSR_PE | SPRD_LSR_FE;
426 	if (termios->c_iflag & IGNBRK) {
427 		port->ignore_status_mask |= SPRD_LSR_BI;
428 		/*
429 		 * If we're ignoring parity and break indicators,
430 		 * ignore overruns too (for real raw support).
431 		 */
432 		if (termios->c_iflag & IGNPAR)
433 			port->ignore_status_mask |= SPRD_LSR_OE;
434 	}
435 
436 	/* flow control */
437 	fc = serial_in(port, SPRD_CTL1);
438 	fc &= ~(RX_HW_FLOW_CTL_THLD | RX_HW_FLOW_CTL_EN | TX_HW_FLOW_CTL_EN);
439 	if (termios->c_cflag & CRTSCTS) {
440 		fc |= RX_HW_FLOW_CTL_THLD;
441 		fc |= RX_HW_FLOW_CTL_EN;
442 		fc |= TX_HW_FLOW_CTL_EN;
443 	}
444 
445 	/* clock divider bit0~bit15 */
446 	serial_out(port, SPRD_CLKD0, quot & SPRD_CLKD0_MASK);
447 
448 	/* clock divider bit16~bit20 */
449 	serial_out(port, SPRD_CLKD1,
450 		   (quot & SPRD_CLKD1_MASK) >> SPRD_CLKD1_SHIFT);
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, struct serial_struct *ser)
484 {
485 	if (ser->type != PORT_SPRD)
486 		return -EINVAL;
487 	if (port->irq != ser->irq)
488 		return -EINVAL;
489 	if (port->iotype != ser->io_type)
490 		return -EINVAL;
491 	return 0;
492 }
493 
494 static const struct uart_ops serial_sprd_ops = {
495 	.tx_empty = sprd_tx_empty,
496 	.get_mctrl = sprd_get_mctrl,
497 	.set_mctrl = sprd_set_mctrl,
498 	.stop_tx = sprd_stop_tx,
499 	.start_tx = sprd_start_tx,
500 	.stop_rx = sprd_stop_rx,
501 	.break_ctl = sprd_break_ctl,
502 	.startup = sprd_startup,
503 	.shutdown = sprd_shutdown,
504 	.set_termios = sprd_set_termios,
505 	.type = sprd_type,
506 	.release_port = sprd_release_port,
507 	.request_port = sprd_request_port,
508 	.config_port = sprd_config_port,
509 	.verify_port = sprd_verify_port,
510 };
511 
512 #ifdef CONFIG_SERIAL_SPRD_CONSOLE
513 static void wait_for_xmitr(struct uart_port *port)
514 {
515 	unsigned int status, tmout = 10000;
516 
517 	/* wait up to 10ms for the character(s) to be sent */
518 	do {
519 		status = serial_in(port, SPRD_STS1);
520 		if (--tmout == 0)
521 			break;
522 		udelay(1);
523 	} while (status & SPRD_TX_FIFO_CNT_MASK);
524 }
525 
526 static void sprd_console_putchar(struct uart_port *port, int ch)
527 {
528 	wait_for_xmitr(port);
529 	serial_out(port, SPRD_TXD, ch);
530 }
531 
532 static void sprd_console_write(struct console *co, const char *s,
533 			       unsigned int count)
534 {
535 	struct uart_port *port = &sprd_port[co->index]->port;
536 	int locked = 1;
537 	unsigned long flags;
538 
539 	if (port->sysrq)
540 		locked = 0;
541 	else if (oops_in_progress)
542 		locked = spin_trylock_irqsave(&port->lock, flags);
543 	else
544 		spin_lock_irqsave(&port->lock, flags);
545 
546 	uart_console_write(port, s, count, sprd_console_putchar);
547 
548 	/* wait for transmitter to become empty */
549 	wait_for_xmitr(port);
550 
551 	if (locked)
552 		spin_unlock_irqrestore(&port->lock, flags);
553 }
554 
555 static int __init sprd_console_setup(struct console *co, char *options)
556 {
557 	struct uart_port *port;
558 	int baud = 115200;
559 	int bits = 8;
560 	int parity = 'n';
561 	int flow = 'n';
562 
563 	if (co->index >= UART_NR_MAX || co->index < 0)
564 		co->index = 0;
565 
566 	port = &sprd_port[co->index]->port;
567 	if (port == NULL) {
568 		pr_info("serial port %d not yet initialized\n", co->index);
569 		return -ENODEV;
570 	}
571 	if (options)
572 		uart_parse_options(options, &baud, &parity, &bits, &flow);
573 
574 	return uart_set_options(port, co, baud, parity, bits, flow);
575 }
576 
577 static struct uart_driver sprd_uart_driver;
578 static struct console sprd_console = {
579 	.name = SPRD_TTY_NAME,
580 	.write = sprd_console_write,
581 	.device = uart_console_device,
582 	.setup = sprd_console_setup,
583 	.flags = CON_PRINTBUFFER,
584 	.index = -1,
585 	.data = &sprd_uart_driver,
586 };
587 
588 #define SPRD_CONSOLE	(&sprd_console)
589 
590 /* Support for earlycon */
591 static void sprd_putc(struct uart_port *port, int c)
592 {
593 	unsigned int timeout = SPRD_TIMEOUT;
594 
595 	while (timeout-- &&
596 	       !(readl(port->membase + SPRD_LSR) & SPRD_LSR_TX_OVER))
597 		cpu_relax();
598 
599 	writeb(c, port->membase + SPRD_TXD);
600 }
601 
602 static void sprd_early_write(struct console *con, const char *s, unsigned int n)
603 {
604 	struct earlycon_device *dev = con->data;
605 
606 	uart_console_write(&dev->port, s, n, sprd_putc);
607 }
608 
609 static int __init sprd_early_console_setup(struct earlycon_device *device,
610 					   const char *opt)
611 {
612 	if (!device->port.membase)
613 		return -ENODEV;
614 
615 	device->con->write = sprd_early_write;
616 	return 0;
617 }
618 OF_EARLYCON_DECLARE(sprd_serial, "sprd,sc9836-uart",
619 		    sprd_early_console_setup);
620 
621 #else /* !CONFIG_SERIAL_SPRD_CONSOLE */
622 #define SPRD_CONSOLE		NULL
623 #endif
624 
625 static struct uart_driver sprd_uart_driver = {
626 	.owner = THIS_MODULE,
627 	.driver_name = "sprd_serial",
628 	.dev_name = SPRD_TTY_NAME,
629 	.major = 0,
630 	.minor = 0,
631 	.nr = UART_NR_MAX,
632 	.cons = SPRD_CONSOLE,
633 };
634 
635 static int sprd_probe_dt_alias(int index, struct device *dev)
636 {
637 	struct device_node *np;
638 	int ret = index;
639 
640 	if (!IS_ENABLED(CONFIG_OF))
641 		return ret;
642 
643 	np = dev->of_node;
644 	if (!np)
645 		return ret;
646 
647 	ret = of_alias_get_id(np, "serial");
648 	if (ret < 0)
649 		ret = index;
650 	else if (ret >= ARRAY_SIZE(sprd_port) || sprd_port[ret] != NULL) {
651 		dev_warn(dev, "requested serial port %d not available.\n", ret);
652 		ret = index;
653 	}
654 
655 	return ret;
656 }
657 
658 static int sprd_remove(struct platform_device *dev)
659 {
660 	struct sprd_uart_port *sup = platform_get_drvdata(dev);
661 
662 	if (sup) {
663 		uart_remove_one_port(&sprd_uart_driver, &sup->port);
664 		sprd_port[sup->port.line] = NULL;
665 		sprd_ports_num--;
666 	}
667 
668 	if (!sprd_ports_num)
669 		uart_unregister_driver(&sprd_uart_driver);
670 
671 	return 0;
672 }
673 
674 static int sprd_probe(struct platform_device *pdev)
675 {
676 	struct resource *res;
677 	struct uart_port *up;
678 	struct clk *clk;
679 	int irq;
680 	int index;
681 	int ret;
682 
683 	for (index = 0; index < ARRAY_SIZE(sprd_port); index++)
684 		if (sprd_port[index] == NULL)
685 			break;
686 
687 	if (index == ARRAY_SIZE(sprd_port))
688 		return -EBUSY;
689 
690 	index = sprd_probe_dt_alias(index, &pdev->dev);
691 
692 	sprd_port[index] = devm_kzalloc(&pdev->dev, sizeof(*sprd_port[index]),
693 					GFP_KERNEL);
694 	if (!sprd_port[index])
695 		return -ENOMEM;
696 
697 	up = &sprd_port[index]->port;
698 	up->dev = &pdev->dev;
699 	up->line = index;
700 	up->type = PORT_SPRD;
701 	up->iotype = UPIO_MEM;
702 	up->uartclk = SPRD_DEF_RATE;
703 	up->fifosize = SPRD_FIFO_SIZE;
704 	up->ops = &serial_sprd_ops;
705 	up->flags = UPF_BOOT_AUTOCONF;
706 
707 	clk = devm_clk_get(&pdev->dev, NULL);
708 	if (!IS_ERR_OR_NULL(clk))
709 		up->uartclk = clk_get_rate(clk);
710 
711 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
712 	up->membase = devm_ioremap_resource(&pdev->dev, res);
713 	if (IS_ERR(up->membase))
714 		return PTR_ERR(up->membase);
715 
716 	up->mapbase = res->start;
717 
718 	irq = platform_get_irq(pdev, 0);
719 	if (irq < 0) {
720 		dev_err(&pdev->dev, "not provide irq resource: %d\n", irq);
721 		return irq;
722 	}
723 	up->irq = irq;
724 
725 	if (!sprd_ports_num) {
726 		ret = uart_register_driver(&sprd_uart_driver);
727 		if (ret < 0) {
728 			pr_err("Failed to register SPRD-UART driver\n");
729 			return ret;
730 		}
731 	}
732 	sprd_ports_num++;
733 
734 	ret = uart_add_one_port(&sprd_uart_driver, up);
735 	if (ret) {
736 		sprd_port[index] = NULL;
737 		sprd_remove(pdev);
738 	}
739 
740 	platform_set_drvdata(pdev, up);
741 
742 	return ret;
743 }
744 
745 #ifdef CONFIG_PM_SLEEP
746 static int sprd_suspend(struct device *dev)
747 {
748 	struct sprd_uart_port *sup = dev_get_drvdata(dev);
749 
750 	uart_suspend_port(&sprd_uart_driver, &sup->port);
751 
752 	return 0;
753 }
754 
755 static int sprd_resume(struct device *dev)
756 {
757 	struct sprd_uart_port *sup = dev_get_drvdata(dev);
758 
759 	uart_resume_port(&sprd_uart_driver, &sup->port);
760 
761 	return 0;
762 }
763 #endif
764 
765 static SIMPLE_DEV_PM_OPS(sprd_pm_ops, sprd_suspend, sprd_resume);
766 
767 static const struct of_device_id serial_ids[] = {
768 	{.compatible = "sprd,sc9836-uart",},
769 	{}
770 };
771 MODULE_DEVICE_TABLE(of, serial_ids);
772 
773 static struct platform_driver sprd_platform_driver = {
774 	.probe		= sprd_probe,
775 	.remove		= sprd_remove,
776 	.driver		= {
777 		.name	= "sprd_serial",
778 		.of_match_table = of_match_ptr(serial_ids),
779 		.pm	= &sprd_pm_ops,
780 	},
781 };
782 
783 module_platform_driver(sprd_platform_driver);
784 
785 MODULE_LICENSE("GPL v2");
786 MODULE_DESCRIPTION("Spreadtrum SoC serial driver series");
787