xref: /linux/drivers/tty/serial/8250/8250_dw.c (revision b4db9f840283caca0d904436f187ef56a9126eaa)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Synopsys DesignWare 8250 driver.
4  *
5  * Copyright 2011 Picochip, Jamie Iles.
6  * Copyright 2013 Intel Corporation
7  *
8  * The Synopsys DesignWare 8250 has an extra feature whereby it detects if the
9  * LCR is written whilst busy.  If it is, then a busy detect interrupt is
10  * raised, the LCR needs to be rewritten and the uart status register read.
11  */
12 #include <linux/clk.h>
13 #include <linux/delay.h>
14 #include <linux/device.h>
15 #include <linux/io.h>
16 #include <linux/mod_devicetable.h>
17 #include <linux/module.h>
18 #include <linux/notifier.h>
19 #include <linux/platform_device.h>
20 #include <linux/pm_runtime.h>
21 #include <linux/property.h>
22 #include <linux/reset.h>
23 #include <linux/slab.h>
24 #include <linux/workqueue.h>
25 
26 #include <asm/byteorder.h>
27 
28 #include <linux/serial_8250.h>
29 #include <linux/serial_reg.h>
30 
31 #include "8250_dwlib.h"
32 
33 /* Offsets for the DesignWare specific registers */
34 #define DW_UART_USR	0x1f /* UART Status Register */
35 #define DW_UART_DMASA	0xa8 /* DMA Software Ack */
36 
37 #define OCTEON_UART_USR	0x27 /* UART Status Register */
38 
39 #define RZN1_UART_TDMACR 0x10c /* DMA Control Register Transmit Mode */
40 #define RZN1_UART_RDMACR 0x110 /* DMA Control Register Receive Mode */
41 
42 /* DesignWare specific register fields */
43 #define DW_UART_MCR_SIRE		BIT(6)
44 
45 /* Renesas specific register fields */
46 #define RZN1_UART_xDMACR_DMA_EN		BIT(0)
47 #define RZN1_UART_xDMACR_1_WORD_BURST	(0 << 1)
48 #define RZN1_UART_xDMACR_4_WORD_BURST	(1 << 1)
49 #define RZN1_UART_xDMACR_8_WORD_BURST	(2 << 1)
50 #define RZN1_UART_xDMACR_BLK_SZ(x)	((x) << 3)
51 
52 /* Quirks */
53 #define DW_UART_QUIRK_OCTEON		BIT(0)
54 #define DW_UART_QUIRK_ARMADA_38X	BIT(1)
55 #define DW_UART_QUIRK_SKIP_SET_RATE	BIT(2)
56 #define DW_UART_QUIRK_IS_DMA_FC		BIT(3)
57 #define DW_UART_QUIRK_APMC0D08		BIT(4)
58 
59 static inline struct dw8250_data *clk_to_dw8250_data(struct notifier_block *nb)
60 {
61 	return container_of(nb, struct dw8250_data, clk_notifier);
62 }
63 
64 static inline struct dw8250_data *work_to_dw8250_data(struct work_struct *work)
65 {
66 	return container_of(work, struct dw8250_data, clk_work);
67 }
68 
69 static inline int dw8250_modify_msr(struct uart_port *p, int offset, int value)
70 {
71 	struct dw8250_data *d = to_dw8250_data(p->private_data);
72 
73 	/* Override any modem control signals if needed */
74 	if (offset == UART_MSR) {
75 		value |= d->msr_mask_on;
76 		value &= ~d->msr_mask_off;
77 	}
78 
79 	return value;
80 }
81 
82 static void dw8250_force_idle(struct uart_port *p)
83 {
84 	struct uart_8250_port *up = up_to_u8250p(p);
85 	unsigned int lsr;
86 
87 	serial8250_clear_and_reinit_fifos(up);
88 
89 	/*
90 	 * With PSLVERR_RESP_EN parameter set to 1, the device generates an
91 	 * error response when an attempt to read an empty RBR with FIFO
92 	 * enabled.
93 	 */
94 	if (up->fcr & UART_FCR_ENABLE_FIFO) {
95 		lsr = p->serial_in(p, UART_LSR);
96 		if (!(lsr & UART_LSR_DR))
97 			return;
98 	}
99 
100 	(void)p->serial_in(p, UART_RX);
101 }
102 
103 static void dw8250_check_lcr(struct uart_port *p, int value)
104 {
105 	void __iomem *offset = p->membase + (UART_LCR << p->regshift);
106 	int tries = 1000;
107 
108 	/* Make sure LCR write wasn't ignored */
109 	while (tries--) {
110 		unsigned int lcr = p->serial_in(p, UART_LCR);
111 
112 		if ((value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR))
113 			return;
114 
115 		dw8250_force_idle(p);
116 
117 #ifdef CONFIG_64BIT
118 		if (p->type == PORT_OCTEON)
119 			__raw_writeq(value & 0xff, offset);
120 		else
121 #endif
122 		if (p->iotype == UPIO_MEM32)
123 			writel(value, offset);
124 		else if (p->iotype == UPIO_MEM32BE)
125 			iowrite32be(value, offset);
126 		else
127 			writeb(value, offset);
128 	}
129 	/*
130 	 * FIXME: this deadlocks if port->lock is already held
131 	 * dev_err(p->dev, "Couldn't set LCR to %d\n", value);
132 	 */
133 }
134 
135 /* Returns once the transmitter is empty or we run out of retries */
136 static void dw8250_tx_wait_empty(struct uart_port *p)
137 {
138 	struct uart_8250_port *up = up_to_u8250p(p);
139 	unsigned int tries = 20000;
140 	unsigned int delay_threshold = tries - 1000;
141 	unsigned int lsr;
142 
143 	while (tries--) {
144 		lsr = readb (p->membase + (UART_LSR << p->regshift));
145 		up->lsr_saved_flags |= lsr & up->lsr_save_mask;
146 
147 		if (lsr & UART_LSR_TEMT)
148 			break;
149 
150 		/* The device is first given a chance to empty without delay,
151 		 * to avoid slowdowns at high bitrates. If after 1000 tries
152 		 * the buffer has still not emptied, allow more time for low-
153 		 * speed links. */
154 		if (tries < delay_threshold)
155 			udelay (1);
156 	}
157 }
158 
159 static void dw8250_serial_out(struct uart_port *p, int offset, int value)
160 {
161 	struct dw8250_data *d = to_dw8250_data(p->private_data);
162 
163 	writeb(value, p->membase + (offset << p->regshift));
164 
165 	if (offset == UART_LCR && !d->uart_16550_compatible)
166 		dw8250_check_lcr(p, value);
167 }
168 
169 static void dw8250_serial_out38x(struct uart_port *p, int offset, int value)
170 {
171 	/* Allow the TX to drain before we reconfigure */
172 	if (offset == UART_LCR)
173 		dw8250_tx_wait_empty(p);
174 
175 	dw8250_serial_out(p, offset, value);
176 }
177 
178 static unsigned int dw8250_serial_in(struct uart_port *p, int offset)
179 {
180 	unsigned int value = readb(p->membase + (offset << p->regshift));
181 
182 	return dw8250_modify_msr(p, offset, value);
183 }
184 
185 #ifdef CONFIG_64BIT
186 static unsigned int dw8250_serial_inq(struct uart_port *p, int offset)
187 {
188 	unsigned int value;
189 
190 	value = (u8)__raw_readq(p->membase + (offset << p->regshift));
191 
192 	return dw8250_modify_msr(p, offset, value);
193 }
194 
195 static void dw8250_serial_outq(struct uart_port *p, int offset, int value)
196 {
197 	struct dw8250_data *d = to_dw8250_data(p->private_data);
198 
199 	value &= 0xff;
200 	__raw_writeq(value, p->membase + (offset << p->regshift));
201 	/* Read back to ensure register write ordering. */
202 	__raw_readq(p->membase + (UART_LCR << p->regshift));
203 
204 	if (offset == UART_LCR && !d->uart_16550_compatible)
205 		dw8250_check_lcr(p, value);
206 }
207 #endif /* CONFIG_64BIT */
208 
209 static void dw8250_serial_out32(struct uart_port *p, int offset, int value)
210 {
211 	struct dw8250_data *d = to_dw8250_data(p->private_data);
212 
213 	writel(value, p->membase + (offset << p->regshift));
214 
215 	if (offset == UART_LCR && !d->uart_16550_compatible)
216 		dw8250_check_lcr(p, value);
217 }
218 
219 static unsigned int dw8250_serial_in32(struct uart_port *p, int offset)
220 {
221 	unsigned int value = readl(p->membase + (offset << p->regshift));
222 
223 	return dw8250_modify_msr(p, offset, value);
224 }
225 
226 static void dw8250_serial_out32be(struct uart_port *p, int offset, int value)
227 {
228 	struct dw8250_data *d = to_dw8250_data(p->private_data);
229 
230 	iowrite32be(value, p->membase + (offset << p->regshift));
231 
232 	if (offset == UART_LCR && !d->uart_16550_compatible)
233 		dw8250_check_lcr(p, value);
234 }
235 
236 static unsigned int dw8250_serial_in32be(struct uart_port *p, int offset)
237 {
238        unsigned int value = ioread32be(p->membase + (offset << p->regshift));
239 
240        return dw8250_modify_msr(p, offset, value);
241 }
242 
243 
244 static int dw8250_handle_irq(struct uart_port *p)
245 {
246 	struct uart_8250_port *up = up_to_u8250p(p);
247 	struct dw8250_data *d = to_dw8250_data(p->private_data);
248 	unsigned int iir = p->serial_in(p, UART_IIR);
249 	bool rx_timeout = (iir & 0x3f) == UART_IIR_RX_TIMEOUT;
250 	unsigned int quirks = d->pdata->quirks;
251 	unsigned int status;
252 	unsigned long flags;
253 
254 	/*
255 	 * There are ways to get Designware-based UARTs into a state where
256 	 * they are asserting UART_IIR_RX_TIMEOUT but there is no actual
257 	 * data available.  If we see such a case then we'll do a bogus
258 	 * read.  If we don't do this then the "RX TIMEOUT" interrupt will
259 	 * fire forever.
260 	 *
261 	 * This problem has only been observed so far when not in DMA mode
262 	 * so we limit the workaround only to non-DMA mode.
263 	 */
264 	if (!up->dma && rx_timeout) {
265 		uart_port_lock_irqsave(p, &flags);
266 		status = serial_lsr_in(up);
267 
268 		if (!(status & (UART_LSR_DR | UART_LSR_BI)))
269 			(void) p->serial_in(p, UART_RX);
270 
271 		uart_port_unlock_irqrestore(p, flags);
272 	}
273 
274 	/* Manually stop the Rx DMA transfer when acting as flow controller */
275 	if (quirks & DW_UART_QUIRK_IS_DMA_FC && up->dma && up->dma->rx_running && rx_timeout) {
276 		uart_port_lock_irqsave(p, &flags);
277 		status = serial_lsr_in(up);
278 		uart_port_unlock_irqrestore(p, flags);
279 
280 		if (status & (UART_LSR_DR | UART_LSR_BI)) {
281 			dw8250_writel_ext(p, RZN1_UART_RDMACR, 0);
282 			dw8250_writel_ext(p, DW_UART_DMASA, 1);
283 		}
284 	}
285 
286 	if (serial8250_handle_irq(p, iir))
287 		return 1;
288 
289 	if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY) {
290 		/* Clear the USR */
291 		(void)p->serial_in(p, d->pdata->usr_reg);
292 
293 		return 1;
294 	}
295 
296 	return 0;
297 }
298 
299 static void dw8250_clk_work_cb(struct work_struct *work)
300 {
301 	struct dw8250_data *d = work_to_dw8250_data(work);
302 	struct uart_8250_port *up;
303 	unsigned long rate;
304 
305 	rate = clk_get_rate(d->clk);
306 	if (rate <= 0)
307 		return;
308 
309 	up = serial8250_get_port(d->data.line);
310 
311 	serial8250_update_uartclk(&up->port, rate);
312 }
313 
314 static int dw8250_clk_notifier_cb(struct notifier_block *nb,
315 				  unsigned long event, void *data)
316 {
317 	struct dw8250_data *d = clk_to_dw8250_data(nb);
318 
319 	/*
320 	 * We have no choice but to defer the uartclk update due to two
321 	 * deadlocks. First one is caused by a recursive mutex lock which
322 	 * happens when clk_set_rate() is called from dw8250_set_termios().
323 	 * Second deadlock is more tricky and is caused by an inverted order of
324 	 * the clk and tty-port mutexes lock. It happens if clock rate change
325 	 * is requested asynchronously while set_termios() is executed between
326 	 * tty-port mutex lock and clk_set_rate() function invocation and
327 	 * vise-versa. Anyway if we didn't have the reference clock alteration
328 	 * in the dw8250_set_termios() method we wouldn't have needed this
329 	 * deferred event handling complication.
330 	 */
331 	if (event == POST_RATE_CHANGE) {
332 		queue_work(system_unbound_wq, &d->clk_work);
333 		return NOTIFY_OK;
334 	}
335 
336 	return NOTIFY_DONE;
337 }
338 
339 static void
340 dw8250_do_pm(struct uart_port *port, unsigned int state, unsigned int old)
341 {
342 	if (!state)
343 		pm_runtime_get_sync(port->dev);
344 
345 	serial8250_do_pm(port, state, old);
346 
347 	if (state)
348 		pm_runtime_put_sync_suspend(port->dev);
349 }
350 
351 static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
352 			       const struct ktermios *old)
353 {
354 	unsigned long newrate = tty_termios_baud_rate(termios) * 16;
355 	struct dw8250_data *d = to_dw8250_data(p->private_data);
356 	long rate;
357 	int ret;
358 
359 	rate = clk_round_rate(d->clk, newrate);
360 	if (rate > 0 && p->uartclk != rate) {
361 		clk_disable_unprepare(d->clk);
362 		/*
363 		 * Note that any clock-notifer worker will block in
364 		 * serial8250_update_uartclk() until we are done.
365 		 */
366 		ret = clk_set_rate(d->clk, newrate);
367 		if (!ret)
368 			p->uartclk = rate;
369 		clk_prepare_enable(d->clk);
370 	}
371 
372 	dw8250_do_set_termios(p, termios, old);
373 }
374 
375 static void dw8250_set_ldisc(struct uart_port *p, struct ktermios *termios)
376 {
377 	struct uart_8250_port *up = up_to_u8250p(p);
378 	unsigned int mcr = p->serial_in(p, UART_MCR);
379 
380 	if (up->capabilities & UART_CAP_IRDA) {
381 		if (termios->c_line == N_IRDA)
382 			mcr |= DW_UART_MCR_SIRE;
383 		else
384 			mcr &= ~DW_UART_MCR_SIRE;
385 
386 		p->serial_out(p, UART_MCR, mcr);
387 	}
388 	serial8250_do_set_ldisc(p, termios);
389 }
390 
391 /*
392  * dw8250_fallback_dma_filter will prevent the UART from getting just any free
393  * channel on platforms that have DMA engines, but don't have any channels
394  * assigned to the UART.
395  *
396  * REVISIT: This is a work around for limitation in the DMA Engine API. Once the
397  * core problem is fixed, this function is no longer needed.
398  */
399 static bool dw8250_fallback_dma_filter(struct dma_chan *chan, void *param)
400 {
401 	return false;
402 }
403 
404 static bool dw8250_idma_filter(struct dma_chan *chan, void *param)
405 {
406 	return param == chan->device->dev;
407 }
408 
409 static u32 dw8250_rzn1_get_dmacr_burst(int max_burst)
410 {
411 	if (max_burst >= 8)
412 		return RZN1_UART_xDMACR_8_WORD_BURST;
413 	else if (max_burst >= 4)
414 		return RZN1_UART_xDMACR_4_WORD_BURST;
415 	else
416 		return RZN1_UART_xDMACR_1_WORD_BURST;
417 }
418 
419 static void dw8250_prepare_tx_dma(struct uart_8250_port *p)
420 {
421 	struct uart_port *up = &p->port;
422 	struct uart_8250_dma *dma = p->dma;
423 	u32 val;
424 
425 	dw8250_writel_ext(up, RZN1_UART_TDMACR, 0);
426 	val = dw8250_rzn1_get_dmacr_burst(dma->txconf.dst_maxburst) |
427 	      RZN1_UART_xDMACR_BLK_SZ(dma->tx_size) |
428 	      RZN1_UART_xDMACR_DMA_EN;
429 	dw8250_writel_ext(up, RZN1_UART_TDMACR, val);
430 }
431 
432 static void dw8250_prepare_rx_dma(struct uart_8250_port *p)
433 {
434 	struct uart_port *up = &p->port;
435 	struct uart_8250_dma *dma = p->dma;
436 	u32 val;
437 
438 	dw8250_writel_ext(up, RZN1_UART_RDMACR, 0);
439 	val = dw8250_rzn1_get_dmacr_burst(dma->rxconf.src_maxburst) |
440 	      RZN1_UART_xDMACR_BLK_SZ(dma->rx_size) |
441 	      RZN1_UART_xDMACR_DMA_EN;
442 	dw8250_writel_ext(up, RZN1_UART_RDMACR, val);
443 }
444 
445 static void dw8250_quirks(struct uart_port *p, struct dw8250_data *data)
446 {
447 	unsigned int quirks = data->pdata ? data->pdata->quirks : 0;
448 
449 #ifdef CONFIG_64BIT
450 	if (quirks & DW_UART_QUIRK_OCTEON) {
451 		p->serial_in = dw8250_serial_inq;
452 		p->serial_out = dw8250_serial_outq;
453 		p->flags = UPF_SKIP_TEST | UPF_SHARE_IRQ | UPF_FIXED_TYPE;
454 		p->type = PORT_OCTEON;
455 		data->skip_autocfg = true;
456 	}
457 #endif
458 
459 	if (quirks & DW_UART_QUIRK_ARMADA_38X)
460 		p->serial_out = dw8250_serial_out38x;
461 	if (quirks & DW_UART_QUIRK_SKIP_SET_RATE)
462 		p->set_termios = dw8250_do_set_termios;
463 	if (quirks & DW_UART_QUIRK_IS_DMA_FC) {
464 		data->data.dma.txconf.device_fc = 1;
465 		data->data.dma.rxconf.device_fc = 1;
466 		data->data.dma.prepare_tx_dma = dw8250_prepare_tx_dma;
467 		data->data.dma.prepare_rx_dma = dw8250_prepare_rx_dma;
468 	}
469 	if (quirks & DW_UART_QUIRK_APMC0D08) {
470 		p->iotype = UPIO_MEM32;
471 		p->regshift = 2;
472 		p->serial_in = dw8250_serial_in32;
473 		data->uart_16550_compatible = true;
474 	}
475 
476 	/* Platforms with iDMA 64-bit */
477 	if (platform_get_resource_byname(to_platform_device(p->dev),
478 					 IORESOURCE_MEM, "lpss_priv")) {
479 		data->data.dma.rx_param = p->dev->parent;
480 		data->data.dma.tx_param = p->dev->parent;
481 		data->data.dma.fn = dw8250_idma_filter;
482 	}
483 }
484 
485 static void dw8250_reset_control_assert(void *data)
486 {
487 	reset_control_assert(data);
488 }
489 
490 static int dw8250_probe(struct platform_device *pdev)
491 {
492 	struct uart_8250_port uart = {}, *up = &uart;
493 	struct uart_port *p = &up->port;
494 	struct device *dev = &pdev->dev;
495 	struct dw8250_data *data;
496 	struct resource *regs;
497 	int err;
498 
499 	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
500 	if (!regs)
501 		return dev_err_probe(dev, -EINVAL, "no registers defined\n");
502 
503 	spin_lock_init(&p->lock);
504 	p->handle_irq	= dw8250_handle_irq;
505 	p->pm		= dw8250_do_pm;
506 	p->type		= PORT_8250;
507 	p->flags	= UPF_FIXED_PORT;
508 	p->dev		= dev;
509 	p->set_ldisc	= dw8250_set_ldisc;
510 	p->set_termios	= dw8250_set_termios;
511 
512 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
513 	if (!data)
514 		return -ENOMEM;
515 
516 	data->data.dma.fn = dw8250_fallback_dma_filter;
517 	data->pdata = device_get_match_data(p->dev);
518 	p->private_data = &data->data;
519 
520 	data->uart_16550_compatible = device_property_read_bool(dev,
521 						"snps,uart-16550-compatible");
522 
523 	p->mapbase = regs->start;
524 	p->mapsize = resource_size(regs);
525 
526 	p->membase = devm_ioremap(dev, p->mapbase, p->mapsize);
527 	if (!p->membase)
528 		return -ENOMEM;
529 
530 	err = uart_read_port_properties(p);
531 	/* no interrupt -> fall back to polling */
532 	if (err == -ENXIO)
533 		err = 0;
534 	if (err)
535 		return err;
536 
537 	switch (p->iotype) {
538 	case UPIO_MEM:
539 		p->serial_in = dw8250_serial_in;
540 		p->serial_out = dw8250_serial_out;
541 		break;
542 	case UPIO_MEM32:
543 		p->serial_in = dw8250_serial_in32;
544 		p->serial_out = dw8250_serial_out32;
545 		break;
546 	case UPIO_MEM32BE:
547 		p->serial_in = dw8250_serial_in32be;
548 		p->serial_out = dw8250_serial_out32be;
549 		break;
550 	default:
551 		return -ENODEV;
552 	}
553 
554 	if (device_property_read_bool(dev, "dcd-override")) {
555 		/* Always report DCD as active */
556 		data->msr_mask_on |= UART_MSR_DCD;
557 		data->msr_mask_off |= UART_MSR_DDCD;
558 	}
559 
560 	if (device_property_read_bool(dev, "dsr-override")) {
561 		/* Always report DSR as active */
562 		data->msr_mask_on |= UART_MSR_DSR;
563 		data->msr_mask_off |= UART_MSR_DDSR;
564 	}
565 
566 	if (device_property_read_bool(dev, "cts-override")) {
567 		/* Always report CTS as active */
568 		data->msr_mask_on |= UART_MSR_CTS;
569 		data->msr_mask_off |= UART_MSR_DCTS;
570 	}
571 
572 	if (device_property_read_bool(dev, "ri-override")) {
573 		/* Always report Ring indicator as inactive */
574 		data->msr_mask_off |= UART_MSR_RI;
575 		data->msr_mask_off |= UART_MSR_TERI;
576 	}
577 
578 	/* If there is separate baudclk, get the rate from it. */
579 	data->clk = devm_clk_get_optional_enabled(dev, "baudclk");
580 	if (data->clk == NULL)
581 		data->clk = devm_clk_get_optional_enabled(dev, NULL);
582 	if (IS_ERR(data->clk))
583 		return dev_err_probe(dev, PTR_ERR(data->clk),
584 				     "failed to get baudclk\n");
585 
586 	INIT_WORK(&data->clk_work, dw8250_clk_work_cb);
587 	data->clk_notifier.notifier_call = dw8250_clk_notifier_cb;
588 
589 	if (data->clk)
590 		p->uartclk = clk_get_rate(data->clk);
591 
592 	/* If no clock rate is defined, fail. */
593 	if (!p->uartclk)
594 		return dev_err_probe(dev, -EINVAL, "clock rate not defined\n");
595 
596 	data->pclk = devm_clk_get_optional_enabled(dev, "apb_pclk");
597 	if (IS_ERR(data->pclk))
598 		return PTR_ERR(data->pclk);
599 
600 	data->rst = devm_reset_control_get_optional_exclusive(dev, NULL);
601 	if (IS_ERR(data->rst))
602 		return PTR_ERR(data->rst);
603 
604 	reset_control_deassert(data->rst);
605 
606 	err = devm_add_action_or_reset(dev, dw8250_reset_control_assert, data->rst);
607 	if (err)
608 		return err;
609 
610 	dw8250_quirks(p, data);
611 
612 	/* If the Busy Functionality is not implemented, don't handle it */
613 	if (data->uart_16550_compatible)
614 		p->handle_irq = NULL;
615 
616 	if (!data->skip_autocfg)
617 		dw8250_setup_port(p);
618 
619 	/* If we have a valid fifosize, try hooking up DMA */
620 	if (p->fifosize) {
621 		data->data.dma.rxconf.src_maxburst = p->fifosize / 4;
622 		data->data.dma.txconf.dst_maxburst = p->fifosize / 4;
623 		up->dma = &data->data.dma;
624 	}
625 
626 	data->data.line = serial8250_register_8250_port(up);
627 	if (data->data.line < 0)
628 		return data->data.line;
629 
630 	/*
631 	 * Some platforms may provide a reference clock shared between several
632 	 * devices. In this case any clock state change must be known to the
633 	 * UART port at least post factum.
634 	 */
635 	if (data->clk) {
636 		err = clk_notifier_register(data->clk, &data->clk_notifier);
637 		if (err)
638 			return dev_err_probe(dev, err, "Failed to set the clock notifier\n");
639 		queue_work(system_unbound_wq, &data->clk_work);
640 	}
641 
642 	platform_set_drvdata(pdev, data);
643 
644 	pm_runtime_set_active(dev);
645 	pm_runtime_enable(dev);
646 
647 	return 0;
648 }
649 
650 static void dw8250_remove(struct platform_device *pdev)
651 {
652 	struct dw8250_data *data = platform_get_drvdata(pdev);
653 	struct device *dev = &pdev->dev;
654 
655 	pm_runtime_get_sync(dev);
656 
657 	if (data->clk) {
658 		clk_notifier_unregister(data->clk, &data->clk_notifier);
659 
660 		flush_work(&data->clk_work);
661 	}
662 
663 	serial8250_unregister_port(data->data.line);
664 
665 	pm_runtime_disable(dev);
666 	pm_runtime_put_noidle(dev);
667 }
668 
669 static int dw8250_suspend(struct device *dev)
670 {
671 	struct dw8250_data *data = dev_get_drvdata(dev);
672 
673 	serial8250_suspend_port(data->data.line);
674 
675 	return 0;
676 }
677 
678 static int dw8250_resume(struct device *dev)
679 {
680 	struct dw8250_data *data = dev_get_drvdata(dev);
681 
682 	serial8250_resume_port(data->data.line);
683 
684 	return 0;
685 }
686 
687 static int dw8250_runtime_suspend(struct device *dev)
688 {
689 	struct dw8250_data *data = dev_get_drvdata(dev);
690 
691 	clk_disable_unprepare(data->clk);
692 
693 	clk_disable_unprepare(data->pclk);
694 
695 	return 0;
696 }
697 
698 static int dw8250_runtime_resume(struct device *dev)
699 {
700 	struct dw8250_data *data = dev_get_drvdata(dev);
701 
702 	clk_prepare_enable(data->pclk);
703 
704 	clk_prepare_enable(data->clk);
705 
706 	return 0;
707 }
708 
709 static const struct dev_pm_ops dw8250_pm_ops = {
710 	SYSTEM_SLEEP_PM_OPS(dw8250_suspend, dw8250_resume)
711 	RUNTIME_PM_OPS(dw8250_runtime_suspend, dw8250_runtime_resume, NULL)
712 };
713 
714 static const struct dw8250_platform_data dw8250_dw_apb = {
715 	.usr_reg = DW_UART_USR,
716 };
717 
718 static const struct dw8250_platform_data dw8250_octeon_3860_data = {
719 	.usr_reg = OCTEON_UART_USR,
720 	.quirks = DW_UART_QUIRK_OCTEON,
721 };
722 
723 static const struct dw8250_platform_data dw8250_armada_38x_data = {
724 	.usr_reg = DW_UART_USR,
725 	.quirks = DW_UART_QUIRK_ARMADA_38X,
726 };
727 
728 static const struct dw8250_platform_data dw8250_renesas_rzn1_data = {
729 	.usr_reg = DW_UART_USR,
730 	.cpr_val = 0x00012f32,
731 	.quirks = DW_UART_QUIRK_IS_DMA_FC,
732 };
733 
734 static const struct dw8250_platform_data dw8250_starfive_jh7100_data = {
735 	.usr_reg = DW_UART_USR,
736 	.quirks = DW_UART_QUIRK_SKIP_SET_RATE,
737 };
738 
739 static const struct of_device_id dw8250_of_match[] = {
740 	{ .compatible = "snps,dw-apb-uart", .data = &dw8250_dw_apb },
741 	{ .compatible = "cavium,octeon-3860-uart", .data = &dw8250_octeon_3860_data },
742 	{ .compatible = "marvell,armada-38x-uart", .data = &dw8250_armada_38x_data },
743 	{ .compatible = "renesas,rzn1-uart", .data = &dw8250_renesas_rzn1_data },
744 	{ .compatible = "starfive,jh7100-uart", .data = &dw8250_starfive_jh7100_data },
745 	{ /* Sentinel */ }
746 };
747 MODULE_DEVICE_TABLE(of, dw8250_of_match);
748 
749 static const struct dw8250_platform_data dw8250_apmc0d08 = {
750 	.usr_reg = DW_UART_USR,
751 	.quirks = DW_UART_QUIRK_APMC0D08,
752 };
753 
754 static const struct acpi_device_id dw8250_acpi_match[] = {
755 	{ "80860F0A", (kernel_ulong_t)&dw8250_dw_apb },
756 	{ "8086228A", (kernel_ulong_t)&dw8250_dw_apb },
757 	{ "AMD0020", (kernel_ulong_t)&dw8250_dw_apb },
758 	{ "AMDI0020", (kernel_ulong_t)&dw8250_dw_apb },
759 	{ "AMDI0022", (kernel_ulong_t)&dw8250_dw_apb },
760 	{ "APMC0D08", (kernel_ulong_t)&dw8250_apmc0d08 },
761 	{ "BRCM2032", (kernel_ulong_t)&dw8250_dw_apb },
762 	{ "HISI0031", (kernel_ulong_t)&dw8250_dw_apb },
763 	{ "INT33C4", (kernel_ulong_t)&dw8250_dw_apb },
764 	{ "INT33C5", (kernel_ulong_t)&dw8250_dw_apb },
765 	{ "INT3434", (kernel_ulong_t)&dw8250_dw_apb },
766 	{ "INT3435", (kernel_ulong_t)&dw8250_dw_apb },
767 	{ "INTC10EE", (kernel_ulong_t)&dw8250_dw_apb },
768 	{ },
769 };
770 MODULE_DEVICE_TABLE(acpi, dw8250_acpi_match);
771 
772 static struct platform_driver dw8250_platform_driver = {
773 	.driver = {
774 		.name		= "dw-apb-uart",
775 		.pm		= pm_ptr(&dw8250_pm_ops),
776 		.of_match_table	= dw8250_of_match,
777 		.acpi_match_table = dw8250_acpi_match,
778 	},
779 	.probe			= dw8250_probe,
780 	.remove_new		= dw8250_remove,
781 };
782 
783 module_platform_driver(dw8250_platform_driver);
784 
785 MODULE_AUTHOR("Jamie Iles");
786 MODULE_LICENSE("GPL");
787 MODULE_DESCRIPTION("Synopsys DesignWare 8250 serial port driver");
788 MODULE_ALIAS("platform:dw-apb-uart");
789