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  1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 * Actions Semi Owl family serial console
  4 *
  5 * Copyright 2013 Actions Semi Inc.
  6 * Author: Actions Semi, Inc.
  7 *
  8 * Copyright (c) 2016-2017 Andreas Färber
  9 */
 10
 11#include <linux/clk.h>
 12#include <linux/console.h>
 13#include <linux/delay.h>
 14#include <linux/io.h>
 15#include <linux/module.h>
 16#include <linux/of.h>
 17#include <linux/platform_device.h>
 18#include <linux/serial.h>
 19#include <linux/serial_core.h>
 20#include <linux/tty.h>
 21#include <linux/tty_flip.h>
 22
 23#define OWL_UART_PORT_NUM 7
 24#define OWL_UART_DEV_NAME "ttyOWL"
 25
 26#define OWL_UART_CTL	0x000
 27#define OWL_UART_RXDAT	0x004
 28#define OWL_UART_TXDAT	0x008
 29#define OWL_UART_STAT	0x00c
 30
 31#define OWL_UART_CTL_DWLS_MASK		GENMASK(1, 0)
 32#define OWL_UART_CTL_DWLS_5BITS		(0x0 << 0)
 33#define OWL_UART_CTL_DWLS_6BITS		(0x1 << 0)
 34#define OWL_UART_CTL_DWLS_7BITS		(0x2 << 0)
 35#define OWL_UART_CTL_DWLS_8BITS		(0x3 << 0)
 36#define OWL_UART_CTL_STPS_2BITS		BIT(2)
 37#define OWL_UART_CTL_PRS_MASK		GENMASK(6, 4)
 38#define OWL_UART_CTL_PRS_NONE		(0x0 << 4)
 39#define OWL_UART_CTL_PRS_ODD		(0x4 << 4)
 40#define OWL_UART_CTL_PRS_MARK		(0x5 << 4)
 41#define OWL_UART_CTL_PRS_EVEN		(0x6 << 4)
 42#define OWL_UART_CTL_PRS_SPACE		(0x7 << 4)
 43#define OWL_UART_CTL_AFE		BIT(12)
 44#define OWL_UART_CTL_TRFS_TX		BIT(14)
 45#define OWL_UART_CTL_EN			BIT(15)
 46#define OWL_UART_CTL_RXDE		BIT(16)
 47#define OWL_UART_CTL_TXDE		BIT(17)
 48#define OWL_UART_CTL_RXIE		BIT(18)
 49#define OWL_UART_CTL_TXIE		BIT(19)
 50#define OWL_UART_CTL_LBEN		BIT(20)
 51
 52#define OWL_UART_STAT_RIP		BIT(0)
 53#define OWL_UART_STAT_TIP		BIT(1)
 54#define OWL_UART_STAT_RXER		BIT(2)
 55#define OWL_UART_STAT_TFER		BIT(3)
 56#define OWL_UART_STAT_RXST		BIT(4)
 57#define OWL_UART_STAT_RFEM		BIT(5)
 58#define OWL_UART_STAT_TFFU		BIT(6)
 59#define OWL_UART_STAT_CTSS		BIT(7)
 60#define OWL_UART_STAT_RTSS		BIT(8)
 61#define OWL_UART_STAT_TFES		BIT(10)
 62#define OWL_UART_STAT_TRFL_MASK		GENMASK(16, 11)
 63#define OWL_UART_STAT_UTBB		BIT(17)
 64
 65static struct uart_driver owl_uart_driver;
 66
 67struct owl_uart_info {
 68	unsigned int tx_fifosize;
 69};
 70
 71struct owl_uart_port {
 72	struct uart_port port;
 73	struct clk *clk;
 74};
 75
 76#define to_owl_uart_port(prt) container_of(prt, struct owl_uart_port, prt)
 77
 78static struct owl_uart_port *owl_uart_ports[OWL_UART_PORT_NUM];
 79
 80static inline void owl_uart_write(struct uart_port *port, u32 val, unsigned int off)
 81{
 82	writel(val, port->membase + off);
 83}
 84
 85static inline u32 owl_uart_read(struct uart_port *port, unsigned int off)
 86{
 87	return readl(port->membase + off);
 88}
 89
 90static void owl_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 91{
 92	u32 ctl;
 93
 94	ctl = owl_uart_read(port, OWL_UART_CTL);
 95
 96	if (mctrl & TIOCM_LOOP)
 97		ctl |= OWL_UART_CTL_LBEN;
 98	else
 99		ctl &= ~OWL_UART_CTL_LBEN;
100
101	owl_uart_write(port, ctl, OWL_UART_CTL);
102}
103
104static unsigned int owl_uart_get_mctrl(struct uart_port *port)
105{
106	unsigned int mctrl = TIOCM_CAR | TIOCM_DSR;
107	u32 stat, ctl;
108
109	ctl = owl_uart_read(port, OWL_UART_CTL);
110	stat = owl_uart_read(port, OWL_UART_STAT);
111	if (stat & OWL_UART_STAT_RTSS)
112		mctrl |= TIOCM_RTS;
113	if ((stat & OWL_UART_STAT_CTSS) || !(ctl & OWL_UART_CTL_AFE))
114		mctrl |= TIOCM_CTS;
115	return mctrl;
116}
117
118static unsigned int owl_uart_tx_empty(struct uart_port *port)
119{
120	unsigned long flags;
121	u32 val;
122	unsigned int ret;
123
124	spin_lock_irqsave(&port->lock, flags);
125
126	val = owl_uart_read(port, OWL_UART_STAT);
127	ret = (val & OWL_UART_STAT_TFES) ? TIOCSER_TEMT : 0;
128
129	spin_unlock_irqrestore(&port->lock, flags);
130
131	return ret;
132}
133
134static void owl_uart_stop_rx(struct uart_port *port)
135{
136	u32 val;
137
138	val = owl_uart_read(port, OWL_UART_CTL);
139	val &= ~(OWL_UART_CTL_RXIE | OWL_UART_CTL_RXDE);
140	owl_uart_write(port, val, OWL_UART_CTL);
141
142	val = owl_uart_read(port, OWL_UART_STAT);
143	val |= OWL_UART_STAT_RIP;
144	owl_uart_write(port, val, OWL_UART_STAT);
145}
146
147static void owl_uart_stop_tx(struct uart_port *port)
148{
149	u32 val;
150
151	val = owl_uart_read(port, OWL_UART_CTL);
152	val &= ~(OWL_UART_CTL_TXIE | OWL_UART_CTL_TXDE);
153	owl_uart_write(port, val, OWL_UART_CTL);
154
155	val = owl_uart_read(port, OWL_UART_STAT);
156	val |= OWL_UART_STAT_TIP;
157	owl_uart_write(port, val, OWL_UART_STAT);
158}
159
160static void owl_uart_start_tx(struct uart_port *port)
161{
162	u32 val;
163
164	if (uart_tx_stopped(port)) {
165		owl_uart_stop_tx(port);
166		return;
167	}
168
169	val = owl_uart_read(port, OWL_UART_STAT);
170	val |= OWL_UART_STAT_TIP;
171	owl_uart_write(port, val, OWL_UART_STAT);
172
173	val = owl_uart_read(port, OWL_UART_CTL);
174	val |= OWL_UART_CTL_TXIE;
175	owl_uart_write(port, val, OWL_UART_CTL);
176}
177
178static void owl_uart_send_chars(struct uart_port *port)
179{
180	struct circ_buf *xmit = &port->state->xmit;
181	unsigned int ch;
182
183	if (uart_tx_stopped(port))
184		return;
185
186	if (port->x_char) {
187		while (!(owl_uart_read(port, OWL_UART_STAT) & OWL_UART_STAT_TFFU))
188			cpu_relax();
189		owl_uart_write(port, port->x_char, OWL_UART_TXDAT);
190		port->icount.tx++;
191		port->x_char = 0;
192	}
193
194	while (!(owl_uart_read(port, OWL_UART_STAT) & OWL_UART_STAT_TFFU)) {
195		if (uart_circ_empty(xmit))
196			break;
197
198		ch = xmit->buf[xmit->tail];
199		owl_uart_write(port, ch, OWL_UART_TXDAT);
200		xmit->tail = (xmit->tail + 1) & (SERIAL_XMIT_SIZE - 1);
201		port->icount.tx++;
202	}
203
204	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
205		uart_write_wakeup(port);
206
207	if (uart_circ_empty(xmit))
208		owl_uart_stop_tx(port);
209}
210
211static void owl_uart_receive_chars(struct uart_port *port)
212{
213	u32 stat, val;
214
215	val = owl_uart_read(port, OWL_UART_CTL);
216	val &= ~OWL_UART_CTL_TRFS_TX;
217	owl_uart_write(port, val, OWL_UART_CTL);
218
219	stat = owl_uart_read(port, OWL_UART_STAT);
220	while (!(stat & OWL_UART_STAT_RFEM)) {
221		char flag = TTY_NORMAL;
222
223		if (stat & OWL_UART_STAT_RXER)
224			port->icount.overrun++;
225
226		if (stat & OWL_UART_STAT_RXST) {
227			/* We are not able to distinguish the error type. */
228			port->icount.brk++;
229			port->icount.frame++;
230
231			stat &= port->read_status_mask;
232			if (stat & OWL_UART_STAT_RXST)
233				flag = TTY_PARITY;
234		} else
235			port->icount.rx++;
236
237		val = owl_uart_read(port, OWL_UART_RXDAT);
238		val &= 0xff;
239
240		if ((stat & port->ignore_status_mask) == 0)
241			tty_insert_flip_char(&port->state->port, val, flag);
242
243		stat = owl_uart_read(port, OWL_UART_STAT);
244	}
245
246	spin_unlock(&port->lock);
247	tty_flip_buffer_push(&port->state->port);
248	spin_lock(&port->lock);
249}
250
251static irqreturn_t owl_uart_irq(int irq, void *dev_id)
252{
253	struct uart_port *port = dev_id;
254	unsigned long flags;
255	u32 stat;
256
257	spin_lock_irqsave(&port->lock, flags);
258
259	stat = owl_uart_read(port, OWL_UART_STAT);
260
261	if (stat & OWL_UART_STAT_RIP)
262		owl_uart_receive_chars(port);
263
264	if (stat & OWL_UART_STAT_TIP)
265		owl_uart_send_chars(port);
266
267	stat = owl_uart_read(port, OWL_UART_STAT);
268	stat |= OWL_UART_STAT_RIP | OWL_UART_STAT_TIP;
269	owl_uart_write(port, stat, OWL_UART_STAT);
270
271	spin_unlock_irqrestore(&port->lock, flags);
272
273	return IRQ_HANDLED;
274}
275
276static void owl_uart_shutdown(struct uart_port *port)
277{
278	u32 val;
279	unsigned long flags;
280
281	spin_lock_irqsave(&port->lock, flags);
282
283	val = owl_uart_read(port, OWL_UART_CTL);
284	val &= ~(OWL_UART_CTL_TXIE | OWL_UART_CTL_RXIE
285		| OWL_UART_CTL_TXDE | OWL_UART_CTL_RXDE | OWL_UART_CTL_EN);
286	owl_uart_write(port, val, OWL_UART_CTL);
287
288	spin_unlock_irqrestore(&port->lock, flags);
289
290	free_irq(port->irq, port);
291}
292
293static int owl_uart_startup(struct uart_port *port)
294{
295	u32 val;
296	unsigned long flags;
297	int ret;
298
299	ret = request_irq(port->irq, owl_uart_irq, IRQF_TRIGGER_HIGH,
300			"owl-uart", port);
301	if (ret)
302		return ret;
303
304	spin_lock_irqsave(&port->lock, flags);
305
306	val = owl_uart_read(port, OWL_UART_STAT);
307	val |= OWL_UART_STAT_RIP | OWL_UART_STAT_TIP
308		| OWL_UART_STAT_RXER | OWL_UART_STAT_TFER | OWL_UART_STAT_RXST;
309	owl_uart_write(port, val, OWL_UART_STAT);
310
311	val = owl_uart_read(port, OWL_UART_CTL);
312	val |= OWL_UART_CTL_RXIE | OWL_UART_CTL_TXIE;
313	val |= OWL_UART_CTL_EN;
314	owl_uart_write(port, val, OWL_UART_CTL);
315
316	spin_unlock_irqrestore(&port->lock, flags);
317
318	return 0;
319}
320
321static void owl_uart_change_baudrate(struct owl_uart_port *owl_port,
322				     unsigned long baud)
323{
324	clk_set_rate(owl_port->clk, baud * 8);
325}
326
327static void owl_uart_set_termios(struct uart_port *port,
328				 struct ktermios *termios,
329				 struct ktermios *old)
330{
331	struct owl_uart_port *owl_port = to_owl_uart_port(port);
332	unsigned int baud;
333	u32 ctl;
334	unsigned long flags;
335
336	spin_lock_irqsave(&port->lock, flags);
337
338	ctl = owl_uart_read(port, OWL_UART_CTL);
339
340	ctl &= ~OWL_UART_CTL_DWLS_MASK;
341	switch (termios->c_cflag & CSIZE) {
342	case CS5:
343		ctl |= OWL_UART_CTL_DWLS_5BITS;
344		break;
345	case CS6:
346		ctl |= OWL_UART_CTL_DWLS_6BITS;
347		break;
348	case CS7:
349		ctl |= OWL_UART_CTL_DWLS_7BITS;
350		break;
351	case CS8:
352	default:
353		ctl |= OWL_UART_CTL_DWLS_8BITS;
354		break;
355	}
356
357	if (termios->c_cflag & CSTOPB)
358		ctl |= OWL_UART_CTL_STPS_2BITS;
359	else
360		ctl &= ~OWL_UART_CTL_STPS_2BITS;
361
362	ctl &= ~OWL_UART_CTL_PRS_MASK;
363	if (termios->c_cflag & PARENB) {
364		if (termios->c_cflag & CMSPAR) {
365			if (termios->c_cflag & PARODD)
366				ctl |= OWL_UART_CTL_PRS_MARK;
367			else
368				ctl |= OWL_UART_CTL_PRS_SPACE;
369		} else if (termios->c_cflag & PARODD)
370			ctl |= OWL_UART_CTL_PRS_ODD;
371		else
372			ctl |= OWL_UART_CTL_PRS_EVEN;
373	} else
374		ctl |= OWL_UART_CTL_PRS_NONE;
375
376	if (termios->c_cflag & CRTSCTS)
377		ctl |= OWL_UART_CTL_AFE;
378	else
379		ctl &= ~OWL_UART_CTL_AFE;
380
381	owl_uart_write(port, ctl, OWL_UART_CTL);
382
383	baud = uart_get_baud_rate(port, termios, old, 9600, 3200000);
384	owl_uart_change_baudrate(owl_port, baud);
385
386	/* Don't rewrite B0 */
387	if (tty_termios_baud_rate(termios))
388		tty_termios_encode_baud_rate(termios, baud, baud);
389
390	port->read_status_mask |= OWL_UART_STAT_RXER;
391	if (termios->c_iflag & INPCK)
392		port->read_status_mask |= OWL_UART_STAT_RXST;
393
394	uart_update_timeout(port, termios->c_cflag, baud);
395
396	spin_unlock_irqrestore(&port->lock, flags);
397}
398
399static void owl_uart_release_port(struct uart_port *port)
400{
401	struct platform_device *pdev = to_platform_device(port->dev);
402	struct resource *res;
403
404	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
405	if (!res)
406		return;
407
408	if (port->flags & UPF_IOREMAP) {
409		devm_release_mem_region(port->dev, port->mapbase,
410			resource_size(res));
411		devm_iounmap(port->dev, port->membase);
412		port->membase = NULL;
413	}
414}
415
416static int owl_uart_request_port(struct uart_port *port)
417{
418	struct platform_device *pdev = to_platform_device(port->dev);
419	struct resource *res;
420
421	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
422	if (!res)
423		return -ENXIO;
424
425	if (!devm_request_mem_region(port->dev, port->mapbase,
426			resource_size(res), dev_name(port->dev)))
427		return -EBUSY;
428
429	if (port->flags & UPF_IOREMAP) {
430		port->membase = devm_ioremap(port->dev, port->mapbase,
431				resource_size(res));
432		if (!port->membase)
433			return -EBUSY;
434	}
435
436	return 0;
437}
438
439static const char *owl_uart_type(struct uart_port *port)
440{
441	return (port->type == PORT_OWL) ? "owl-uart" : NULL;
442}
443
444static int owl_uart_verify_port(struct uart_port *port,
445				struct serial_struct *ser)
446{
447	if (port->type != PORT_OWL)
448		return -EINVAL;
449
450	if (port->irq != ser->irq)
451		return -EINVAL;
452
453	return 0;
454}
455
456static void owl_uart_config_port(struct uart_port *port, int flags)
457{
458	if (flags & UART_CONFIG_TYPE) {
459		port->type = PORT_OWL;
460		owl_uart_request_port(port);
461	}
462}
463
464static const struct uart_ops owl_uart_ops = {
465	.set_mctrl = owl_uart_set_mctrl,
466	.get_mctrl = owl_uart_get_mctrl,
467	.tx_empty = owl_uart_tx_empty,
468	.start_tx = owl_uart_start_tx,
469	.stop_rx = owl_uart_stop_rx,
470	.stop_tx = owl_uart_stop_tx,
471	.startup = owl_uart_startup,
472	.shutdown = owl_uart_shutdown,
473	.set_termios = owl_uart_set_termios,
474	.type = owl_uart_type,
475	.config_port = owl_uart_config_port,
476	.request_port = owl_uart_request_port,
477	.release_port = owl_uart_release_port,
478	.verify_port = owl_uart_verify_port,
479};
480
481#ifdef CONFIG_SERIAL_OWL_CONSOLE
482
483static void owl_console_putchar(struct uart_port *port, int ch)
484{
485	if (!port->membase)
486		return;
487
488	while (owl_uart_read(port, OWL_UART_STAT) & OWL_UART_STAT_TFFU)
489		cpu_relax();
490
491	owl_uart_write(port, ch, OWL_UART_TXDAT);
492}
493
494static void owl_uart_port_write(struct uart_port *port, const char *s,
495				u_int count)
496{
497	u32 old_ctl, val;
498	unsigned long flags;
499	int locked;
500
501	local_irq_save(flags);
502
503	if (port->sysrq)
504		locked = 0;
505	else if (oops_in_progress)
506		locked = spin_trylock(&port->lock);
507	else {
508		spin_lock(&port->lock);
509		locked = 1;
510	}
511
512	old_ctl = owl_uart_read(port, OWL_UART_CTL);
513	val = old_ctl | OWL_UART_CTL_TRFS_TX;
514	/* disable IRQ */
515	val &= ~(OWL_UART_CTL_RXIE | OWL_UART_CTL_TXIE);
516	owl_uart_write(port, val, OWL_UART_CTL);
517
518	uart_console_write(port, s, count, owl_console_putchar);
519
520	/* wait until all contents have been sent out */
521	while (owl_uart_read(port, OWL_UART_STAT) & OWL_UART_STAT_TRFL_MASK)
522		cpu_relax();
523
524	/* clear IRQ pending */
525	val = owl_uart_read(port, OWL_UART_STAT);
526	val |= OWL_UART_STAT_TIP | OWL_UART_STAT_RIP;
527	owl_uart_write(port, val, OWL_UART_STAT);
528
529	owl_uart_write(port, old_ctl, OWL_UART_CTL);
530
531	if (locked)
532		spin_unlock(&port->lock);
533
534	local_irq_restore(flags);
535}
536
537static void owl_uart_console_write(struct console *co, const char *s,
538				   u_int count)
539{
540	struct owl_uart_port *owl_port;
541
542	owl_port = owl_uart_ports[co->index];
543	if (!owl_port)
544		return;
545
546	owl_uart_port_write(&owl_port->port, s, count);
547}
548
549static int owl_uart_console_setup(struct console *co, char *options)
550{
551	struct owl_uart_port *owl_port;
552	int baud = 115200;
553	int bits = 8;
554	int parity = 'n';
555	int flow = 'n';
556
557	if (co->index < 0 || co->index >= OWL_UART_PORT_NUM)
558		return -EINVAL;
559
560	owl_port = owl_uart_ports[co->index];
561	if (!owl_port || !owl_port->port.membase)
562		return -ENODEV;
563
564	if (options)
565		uart_parse_options(options, &baud, &parity, &bits, &flow);
566
567	return uart_set_options(&owl_port->port, co, baud, parity, bits, flow);
568}
569
570static struct console owl_uart_console = {
571	.name = OWL_UART_DEV_NAME,
572	.write = owl_uart_console_write,
573	.device = uart_console_device,
574	.setup = owl_uart_console_setup,
575	.flags = CON_PRINTBUFFER,
576	.index = -1,
577	.data = &owl_uart_driver,
578};
579
580static int __init owl_uart_console_init(void)
581{
582	register_console(&owl_uart_console);
583
584	return 0;
585}
586console_initcall(owl_uart_console_init);
587
588static void owl_uart_early_console_write(struct console *co,
589					 const char *s,
590					 u_int count)
591{
592	struct earlycon_device *dev = co->data;
593
594	owl_uart_port_write(&dev->port, s, count);
595}
596
597static int __init
598owl_uart_early_console_setup(struct earlycon_device *device, const char *opt)
599{
600	if (!device->port.membase)
601		return -ENODEV;
602
603	device->con->write = owl_uart_early_console_write;
604
605	return 0;
606}
607OF_EARLYCON_DECLARE(owl, "actions,owl-uart",
608		    owl_uart_early_console_setup);
609
610#define OWL_UART_CONSOLE (&owl_uart_console)
611#else
612#define OWL_UART_CONSOLE NULL
613#endif
614
615static struct uart_driver owl_uart_driver = {
616	.owner = THIS_MODULE,
617	.driver_name = "owl-uart",
618	.dev_name = OWL_UART_DEV_NAME,
619	.nr = OWL_UART_PORT_NUM,
620	.cons = OWL_UART_CONSOLE,
621};
622
623static const struct owl_uart_info owl_s500_info = {
624	.tx_fifosize = 16,
625};
626
627static const struct owl_uart_info owl_s900_info = {
628	.tx_fifosize = 32,
629};
630
631static const struct of_device_id owl_uart_dt_matches[] = {
632	{ .compatible = "actions,s500-uart", .data = &owl_s500_info },
633	{ .compatible = "actions,s900-uart", .data = &owl_s900_info },
634	{ }
635};
636MODULE_DEVICE_TABLE(of, owl_uart_dt_matches);
637
638static int owl_uart_probe(struct platform_device *pdev)
639{
640	const struct of_device_id *match;
641	const struct owl_uart_info *info = NULL;
642	struct resource *res_mem;
643	struct owl_uart_port *owl_port;
644	int ret, irq;
645
646	if (pdev->dev.of_node) {
647		pdev->id = of_alias_get_id(pdev->dev.of_node, "serial");
648		match = of_match_node(owl_uart_dt_matches, pdev->dev.of_node);
649		if (match)
650			info = match->data;
651	}
652
653	if (pdev->id < 0 || pdev->id >= OWL_UART_PORT_NUM) {
654		dev_err(&pdev->dev, "id %d out of range\n", pdev->id);
655		return -EINVAL;
656	}
657
658	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
659	if (!res_mem) {
660		dev_err(&pdev->dev, "could not get mem\n");
661		return -ENODEV;
662	}
663
664	irq = platform_get_irq(pdev, 0);
665	if (irq < 0)
666		return irq;
667
668	if (owl_uart_ports[pdev->id]) {
669		dev_err(&pdev->dev, "port %d already allocated\n", pdev->id);
670		return -EBUSY;
671	}
672
673	owl_port = devm_kzalloc(&pdev->dev, sizeof(*owl_port), GFP_KERNEL);
674	if (!owl_port)
675		return -ENOMEM;
676
677	owl_port->clk = devm_clk_get(&pdev->dev, NULL);
678	if (IS_ERR(owl_port->clk)) {
679		dev_err(&pdev->dev, "could not get clk\n");
680		return PTR_ERR(owl_port->clk);
681	}
682
683	ret = clk_prepare_enable(owl_port->clk);
684	if (ret) {
685		dev_err(&pdev->dev, "could not enable clk\n");
686		return ret;
687	}
688
689	owl_port->port.dev = &pdev->dev;
690	owl_port->port.line = pdev->id;
691	owl_port->port.type = PORT_OWL;
692	owl_port->port.iotype = UPIO_MEM;
693	owl_port->port.mapbase = res_mem->start;
694	owl_port->port.irq = irq;
695	owl_port->port.uartclk = clk_get_rate(owl_port->clk);
696	if (owl_port->port.uartclk == 0) {
697		dev_err(&pdev->dev, "clock rate is zero\n");
698		return -EINVAL;
699	}
700	owl_port->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP | UPF_LOW_LATENCY;
701	owl_port->port.x_char = 0;
702	owl_port->port.fifosize = (info) ? info->tx_fifosize : 16;
703	owl_port->port.ops = &owl_uart_ops;
704
705	owl_uart_ports[pdev->id] = owl_port;
706	platform_set_drvdata(pdev, owl_port);
707
708	ret = uart_add_one_port(&owl_uart_driver, &owl_port->port);
709	if (ret)
710		owl_uart_ports[pdev->id] = NULL;
711
712	return ret;
713}
714
715static int owl_uart_remove(struct platform_device *pdev)
716{
717	struct owl_uart_port *owl_port = platform_get_drvdata(pdev);
718
719	uart_remove_one_port(&owl_uart_driver, &owl_port->port);
720	owl_uart_ports[pdev->id] = NULL;
721	clk_disable_unprepare(owl_port->clk);
722
723	return 0;
724}
725
726static struct platform_driver owl_uart_platform_driver = {
727	.probe = owl_uart_probe,
728	.remove = owl_uart_remove,
729	.driver = {
730		.name = "owl-uart",
731		.of_match_table = owl_uart_dt_matches,
732	},
733};
734
735static int __init owl_uart_init(void)
736{
737	int ret;
738
739	ret = uart_register_driver(&owl_uart_driver);
740	if (ret)
741		return ret;
742
743	ret = platform_driver_register(&owl_uart_platform_driver);
744	if (ret)
745		uart_unregister_driver(&owl_uart_driver);
746
747	return ret;
748}
749
750static void __exit owl_uart_exit(void)
751{
752	platform_driver_unregister(&owl_uart_platform_driver);
753	uart_unregister_driver(&owl_uart_driver);
754}
755
756module_init(owl_uart_init);
757module_exit(owl_uart_exit);
758
759MODULE_LICENSE("GPL");