xref: /openbmc/linux/drivers/tty/serial/ar933x_uart.c (revision f7777dcc)
1 /*
2  *  Atheros AR933X SoC built-in UART driver
3  *
4  *  Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
5  *
6  *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
7  *
8  *  This program is free software; you can redistribute it and/or modify it
9  *  under the terms of the GNU General Public License version 2 as published
10  *  by the Free Software Foundation.
11  */
12 
13 #include <linux/module.h>
14 #include <linux/ioport.h>
15 #include <linux/init.h>
16 #include <linux/console.h>
17 #include <linux/sysrq.h>
18 #include <linux/delay.h>
19 #include <linux/platform_device.h>
20 #include <linux/of.h>
21 #include <linux/of_platform.h>
22 #include <linux/tty.h>
23 #include <linux/tty_flip.h>
24 #include <linux/serial_core.h>
25 #include <linux/serial.h>
26 #include <linux/slab.h>
27 #include <linux/io.h>
28 #include <linux/irq.h>
29 #include <linux/clk.h>
30 
31 #include <asm/div64.h>
32 
33 #include <asm/mach-ath79/ar933x_uart.h>
34 
35 #define DRIVER_NAME "ar933x-uart"
36 
37 #define AR933X_UART_MAX_SCALE	0xff
38 #define AR933X_UART_MAX_STEP	0xffff
39 
40 #define AR933X_UART_MIN_BAUD	300
41 #define AR933X_UART_MAX_BAUD	3000000
42 
43 #define AR933X_DUMMY_STATUS_RD	0x01
44 
45 static struct uart_driver ar933x_uart_driver;
46 
47 struct ar933x_uart_port {
48 	struct uart_port	port;
49 	unsigned int		ier;	/* shadow Interrupt Enable Register */
50 	unsigned int		min_baud;
51 	unsigned int		max_baud;
52 	struct clk		*clk;
53 };
54 
55 static inline bool ar933x_uart_console_enabled(void)
56 {
57 	return config_enabled(CONFIG_SERIAL_AR933X_CONSOLE);
58 }
59 
60 static inline unsigned int ar933x_uart_read(struct ar933x_uart_port *up,
61 					    int offset)
62 {
63 	return readl(up->port.membase + offset);
64 }
65 
66 static inline void ar933x_uart_write(struct ar933x_uart_port *up,
67 				     int offset, unsigned int value)
68 {
69 	writel(value, up->port.membase + offset);
70 }
71 
72 static inline void ar933x_uart_rmw(struct ar933x_uart_port *up,
73 				  unsigned int offset,
74 				  unsigned int mask,
75 				  unsigned int val)
76 {
77 	unsigned int t;
78 
79 	t = ar933x_uart_read(up, offset);
80 	t &= ~mask;
81 	t |= val;
82 	ar933x_uart_write(up, offset, t);
83 }
84 
85 static inline void ar933x_uart_rmw_set(struct ar933x_uart_port *up,
86 				       unsigned int offset,
87 				       unsigned int val)
88 {
89 	ar933x_uart_rmw(up, offset, 0, val);
90 }
91 
92 static inline void ar933x_uart_rmw_clear(struct ar933x_uart_port *up,
93 					 unsigned int offset,
94 					 unsigned int val)
95 {
96 	ar933x_uart_rmw(up, offset, val, 0);
97 }
98 
99 static inline void ar933x_uart_start_tx_interrupt(struct ar933x_uart_port *up)
100 {
101 	up->ier |= AR933X_UART_INT_TX_EMPTY;
102 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
103 }
104 
105 static inline void ar933x_uart_stop_tx_interrupt(struct ar933x_uart_port *up)
106 {
107 	up->ier &= ~AR933X_UART_INT_TX_EMPTY;
108 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
109 }
110 
111 static inline void ar933x_uart_putc(struct ar933x_uart_port *up, int ch)
112 {
113 	unsigned int rdata;
114 
115 	rdata = ch & AR933X_UART_DATA_TX_RX_MASK;
116 	rdata |= AR933X_UART_DATA_TX_CSR;
117 	ar933x_uart_write(up, AR933X_UART_DATA_REG, rdata);
118 }
119 
120 static unsigned int ar933x_uart_tx_empty(struct uart_port *port)
121 {
122 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
123 	unsigned long flags;
124 	unsigned int rdata;
125 
126 	spin_lock_irqsave(&up->port.lock, flags);
127 	rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
128 	spin_unlock_irqrestore(&up->port.lock, flags);
129 
130 	return (rdata & AR933X_UART_DATA_TX_CSR) ? 0 : TIOCSER_TEMT;
131 }
132 
133 static unsigned int ar933x_uart_get_mctrl(struct uart_port *port)
134 {
135 	return TIOCM_CAR;
136 }
137 
138 static void ar933x_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
139 {
140 }
141 
142 static void ar933x_uart_start_tx(struct uart_port *port)
143 {
144 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
145 
146 	ar933x_uart_start_tx_interrupt(up);
147 }
148 
149 static void ar933x_uart_stop_tx(struct uart_port *port)
150 {
151 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
152 
153 	ar933x_uart_stop_tx_interrupt(up);
154 }
155 
156 static void ar933x_uart_stop_rx(struct uart_port *port)
157 {
158 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
159 
160 	up->ier &= ~AR933X_UART_INT_RX_VALID;
161 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
162 }
163 
164 static void ar933x_uart_break_ctl(struct uart_port *port, int break_state)
165 {
166 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
167 	unsigned long flags;
168 
169 	spin_lock_irqsave(&up->port.lock, flags);
170 	if (break_state == -1)
171 		ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
172 				    AR933X_UART_CS_TX_BREAK);
173 	else
174 		ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
175 				      AR933X_UART_CS_TX_BREAK);
176 	spin_unlock_irqrestore(&up->port.lock, flags);
177 }
178 
179 static void ar933x_uart_enable_ms(struct uart_port *port)
180 {
181 }
182 
183 /*
184  * baudrate = (clk / (scale + 1)) * (step * (1 / 2^17))
185  */
186 static unsigned long ar933x_uart_get_baud(unsigned int clk,
187 					  unsigned int scale,
188 					  unsigned int step)
189 {
190 	u64 t;
191 	u32 div;
192 
193 	div = (2 << 16) * (scale + 1);
194 	t = clk;
195 	t *= step;
196 	t += (div / 2);
197 	do_div(t, div);
198 
199 	return t;
200 }
201 
202 static void ar933x_uart_get_scale_step(unsigned int clk,
203 				       unsigned int baud,
204 				       unsigned int *scale,
205 				       unsigned int *step)
206 {
207 	unsigned int tscale;
208 	long min_diff;
209 
210 	*scale = 0;
211 	*step = 0;
212 
213 	min_diff = baud;
214 	for (tscale = 0; tscale < AR933X_UART_MAX_SCALE; tscale++) {
215 		u64 tstep;
216 		int diff;
217 
218 		tstep = baud * (tscale + 1);
219 		tstep *= (2 << 16);
220 		do_div(tstep, clk);
221 
222 		if (tstep > AR933X_UART_MAX_STEP)
223 			break;
224 
225 		diff = abs(ar933x_uart_get_baud(clk, tscale, tstep) - baud);
226 		if (diff < min_diff) {
227 			min_diff = diff;
228 			*scale = tscale;
229 			*step = tstep;
230 		}
231 	}
232 }
233 
234 static void ar933x_uart_set_termios(struct uart_port *port,
235 				    struct ktermios *new,
236 				    struct ktermios *old)
237 {
238 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
239 	unsigned int cs;
240 	unsigned long flags;
241 	unsigned int baud, scale, step;
242 
243 	/* Only CS8 is supported */
244 	new->c_cflag &= ~CSIZE;
245 	new->c_cflag |= CS8;
246 
247 	/* Only one stop bit is supported */
248 	new->c_cflag &= ~CSTOPB;
249 
250 	cs = 0;
251 	if (new->c_cflag & PARENB) {
252 		if (!(new->c_cflag & PARODD))
253 			cs |= AR933X_UART_CS_PARITY_EVEN;
254 		else
255 			cs |= AR933X_UART_CS_PARITY_ODD;
256 	} else {
257 		cs |= AR933X_UART_CS_PARITY_NONE;
258 	}
259 
260 	/* Mark/space parity is not supported */
261 	new->c_cflag &= ~CMSPAR;
262 
263 	baud = uart_get_baud_rate(port, new, old, up->min_baud, up->max_baud);
264 	ar933x_uart_get_scale_step(port->uartclk, baud, &scale, &step);
265 
266 	/*
267 	 * Ok, we're now changing the port state. Do it with
268 	 * interrupts disabled.
269 	 */
270 	spin_lock_irqsave(&up->port.lock, flags);
271 
272 	/* disable the UART */
273 	ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
274 		      AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S);
275 
276 	/* Update the per-port timeout. */
277 	uart_update_timeout(port, new->c_cflag, baud);
278 
279 	up->port.ignore_status_mask = 0;
280 
281 	/* ignore all characters if CREAD is not set */
282 	if ((new->c_cflag & CREAD) == 0)
283 		up->port.ignore_status_mask |= AR933X_DUMMY_STATUS_RD;
284 
285 	ar933x_uart_write(up, AR933X_UART_CLOCK_REG,
286 			  scale << AR933X_UART_CLOCK_SCALE_S | step);
287 
288 	/* setup configuration register */
289 	ar933x_uart_rmw(up, AR933X_UART_CS_REG, AR933X_UART_CS_PARITY_M, cs);
290 
291 	/* enable host interrupt */
292 	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
293 			    AR933X_UART_CS_HOST_INT_EN);
294 
295 	/* reenable the UART */
296 	ar933x_uart_rmw(up, AR933X_UART_CS_REG,
297 			AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S,
298 			AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S);
299 
300 	spin_unlock_irqrestore(&up->port.lock, flags);
301 
302 	if (tty_termios_baud_rate(new))
303 		tty_termios_encode_baud_rate(new, baud, baud);
304 }
305 
306 static void ar933x_uart_rx_chars(struct ar933x_uart_port *up)
307 {
308 	struct tty_port *port = &up->port.state->port;
309 	int max_count = 256;
310 
311 	do {
312 		unsigned int rdata;
313 		unsigned char ch;
314 
315 		rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
316 		if ((rdata & AR933X_UART_DATA_RX_CSR) == 0)
317 			break;
318 
319 		/* remove the character from the FIFO */
320 		ar933x_uart_write(up, AR933X_UART_DATA_REG,
321 				  AR933X_UART_DATA_RX_CSR);
322 
323 		up->port.icount.rx++;
324 		ch = rdata & AR933X_UART_DATA_TX_RX_MASK;
325 
326 		if (uart_handle_sysrq_char(&up->port, ch))
327 			continue;
328 
329 		if ((up->port.ignore_status_mask & AR933X_DUMMY_STATUS_RD) == 0)
330 			tty_insert_flip_char(port, ch, TTY_NORMAL);
331 	} while (max_count-- > 0);
332 
333 	spin_unlock(&up->port.lock);
334 	tty_flip_buffer_push(port);
335 	spin_lock(&up->port.lock);
336 }
337 
338 static void ar933x_uart_tx_chars(struct ar933x_uart_port *up)
339 {
340 	struct circ_buf *xmit = &up->port.state->xmit;
341 	int count;
342 
343 	if (uart_tx_stopped(&up->port))
344 		return;
345 
346 	count = up->port.fifosize;
347 	do {
348 		unsigned int rdata;
349 
350 		rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
351 		if ((rdata & AR933X_UART_DATA_TX_CSR) == 0)
352 			break;
353 
354 		if (up->port.x_char) {
355 			ar933x_uart_putc(up, up->port.x_char);
356 			up->port.icount.tx++;
357 			up->port.x_char = 0;
358 			continue;
359 		}
360 
361 		if (uart_circ_empty(xmit))
362 			break;
363 
364 		ar933x_uart_putc(up, xmit->buf[xmit->tail]);
365 
366 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
367 		up->port.icount.tx++;
368 	} while (--count > 0);
369 
370 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
371 		uart_write_wakeup(&up->port);
372 
373 	if (!uart_circ_empty(xmit))
374 		ar933x_uart_start_tx_interrupt(up);
375 }
376 
377 static irqreturn_t ar933x_uart_interrupt(int irq, void *dev_id)
378 {
379 	struct ar933x_uart_port *up = dev_id;
380 	unsigned int status;
381 
382 	status = ar933x_uart_read(up, AR933X_UART_CS_REG);
383 	if ((status & AR933X_UART_CS_HOST_INT) == 0)
384 		return IRQ_NONE;
385 
386 	spin_lock(&up->port.lock);
387 
388 	status = ar933x_uart_read(up, AR933X_UART_INT_REG);
389 	status &= ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
390 
391 	if (status & AR933X_UART_INT_RX_VALID) {
392 		ar933x_uart_write(up, AR933X_UART_INT_REG,
393 				  AR933X_UART_INT_RX_VALID);
394 		ar933x_uart_rx_chars(up);
395 	}
396 
397 	if (status & AR933X_UART_INT_TX_EMPTY) {
398 		ar933x_uart_write(up, AR933X_UART_INT_REG,
399 				  AR933X_UART_INT_TX_EMPTY);
400 		ar933x_uart_stop_tx_interrupt(up);
401 		ar933x_uart_tx_chars(up);
402 	}
403 
404 	spin_unlock(&up->port.lock);
405 
406 	return IRQ_HANDLED;
407 }
408 
409 static int ar933x_uart_startup(struct uart_port *port)
410 {
411 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
412 	unsigned long flags;
413 	int ret;
414 
415 	ret = request_irq(up->port.irq, ar933x_uart_interrupt,
416 			  up->port.irqflags, dev_name(up->port.dev), up);
417 	if (ret)
418 		return ret;
419 
420 	spin_lock_irqsave(&up->port.lock, flags);
421 
422 	/* Enable HOST interrupts */
423 	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
424 			    AR933X_UART_CS_HOST_INT_EN);
425 
426 	/* Enable RX interrupts */
427 	up->ier = AR933X_UART_INT_RX_VALID;
428 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
429 
430 	spin_unlock_irqrestore(&up->port.lock, flags);
431 
432 	return 0;
433 }
434 
435 static void ar933x_uart_shutdown(struct uart_port *port)
436 {
437 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
438 
439 	/* Disable all interrupts */
440 	up->ier = 0;
441 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
442 
443 	/* Disable break condition */
444 	ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
445 			      AR933X_UART_CS_TX_BREAK);
446 
447 	free_irq(up->port.irq, up);
448 }
449 
450 static const char *ar933x_uart_type(struct uart_port *port)
451 {
452 	return (port->type == PORT_AR933X) ? "AR933X UART" : NULL;
453 }
454 
455 static void ar933x_uart_release_port(struct uart_port *port)
456 {
457 	/* Nothing to release ... */
458 }
459 
460 static int ar933x_uart_request_port(struct uart_port *port)
461 {
462 	/* UARTs always present */
463 	return 0;
464 }
465 
466 static void ar933x_uart_config_port(struct uart_port *port, int flags)
467 {
468 	if (flags & UART_CONFIG_TYPE)
469 		port->type = PORT_AR933X;
470 }
471 
472 static int ar933x_uart_verify_port(struct uart_port *port,
473 				   struct serial_struct *ser)
474 {
475 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
476 
477 	if (ser->type != PORT_UNKNOWN &&
478 	    ser->type != PORT_AR933X)
479 		return -EINVAL;
480 
481 	if (ser->irq < 0 || ser->irq >= NR_IRQS)
482 		return -EINVAL;
483 
484 	if (ser->baud_base < up->min_baud ||
485 	    ser->baud_base > up->max_baud)
486 		return -EINVAL;
487 
488 	return 0;
489 }
490 
491 static struct uart_ops ar933x_uart_ops = {
492 	.tx_empty	= ar933x_uart_tx_empty,
493 	.set_mctrl	= ar933x_uart_set_mctrl,
494 	.get_mctrl	= ar933x_uart_get_mctrl,
495 	.stop_tx	= ar933x_uart_stop_tx,
496 	.start_tx	= ar933x_uart_start_tx,
497 	.stop_rx	= ar933x_uart_stop_rx,
498 	.enable_ms	= ar933x_uart_enable_ms,
499 	.break_ctl	= ar933x_uart_break_ctl,
500 	.startup	= ar933x_uart_startup,
501 	.shutdown	= ar933x_uart_shutdown,
502 	.set_termios	= ar933x_uart_set_termios,
503 	.type		= ar933x_uart_type,
504 	.release_port	= ar933x_uart_release_port,
505 	.request_port	= ar933x_uart_request_port,
506 	.config_port	= ar933x_uart_config_port,
507 	.verify_port	= ar933x_uart_verify_port,
508 };
509 
510 static struct ar933x_uart_port *
511 ar933x_console_ports[CONFIG_SERIAL_AR933X_NR_UARTS];
512 
513 static void ar933x_uart_wait_xmitr(struct ar933x_uart_port *up)
514 {
515 	unsigned int status;
516 	unsigned int timeout = 60000;
517 
518 	/* Wait up to 60ms for the character(s) to be sent. */
519 	do {
520 		status = ar933x_uart_read(up, AR933X_UART_DATA_REG);
521 		if (--timeout == 0)
522 			break;
523 		udelay(1);
524 	} while ((status & AR933X_UART_DATA_TX_CSR) == 0);
525 }
526 
527 static void ar933x_uart_console_putchar(struct uart_port *port, int ch)
528 {
529 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
530 
531 	ar933x_uart_wait_xmitr(up);
532 	ar933x_uart_putc(up, ch);
533 }
534 
535 static void ar933x_uart_console_write(struct console *co, const char *s,
536 				      unsigned int count)
537 {
538 	struct ar933x_uart_port *up = ar933x_console_ports[co->index];
539 	unsigned long flags;
540 	unsigned int int_en;
541 	int locked = 1;
542 
543 	local_irq_save(flags);
544 
545 	if (up->port.sysrq)
546 		locked = 0;
547 	else if (oops_in_progress)
548 		locked = spin_trylock(&up->port.lock);
549 	else
550 		spin_lock(&up->port.lock);
551 
552 	/*
553 	 * First save the IER then disable the interrupts
554 	 */
555 	int_en = ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
556 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0);
557 
558 	uart_console_write(&up->port, s, count, ar933x_uart_console_putchar);
559 
560 	/*
561 	 * Finally, wait for transmitter to become empty
562 	 * and restore the IER
563 	 */
564 	ar933x_uart_wait_xmitr(up);
565 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, int_en);
566 
567 	ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_ALLINTS);
568 
569 	if (locked)
570 		spin_unlock(&up->port.lock);
571 
572 	local_irq_restore(flags);
573 }
574 
575 static int ar933x_uart_console_setup(struct console *co, char *options)
576 {
577 	struct ar933x_uart_port *up;
578 	int baud = 115200;
579 	int bits = 8;
580 	int parity = 'n';
581 	int flow = 'n';
582 
583 	if (co->index < 0 || co->index >= CONFIG_SERIAL_AR933X_NR_UARTS)
584 		return -EINVAL;
585 
586 	up = ar933x_console_ports[co->index];
587 	if (!up)
588 		return -ENODEV;
589 
590 	if (options)
591 		uart_parse_options(options, &baud, &parity, &bits, &flow);
592 
593 	return uart_set_options(&up->port, co, baud, parity, bits, flow);
594 }
595 
596 static struct console ar933x_uart_console = {
597 	.name		= "ttyATH",
598 	.write		= ar933x_uart_console_write,
599 	.device		= uart_console_device,
600 	.setup		= ar933x_uart_console_setup,
601 	.flags		= CON_PRINTBUFFER,
602 	.index		= -1,
603 	.data		= &ar933x_uart_driver,
604 };
605 
606 static void ar933x_uart_add_console_port(struct ar933x_uart_port *up)
607 {
608 	if (!ar933x_uart_console_enabled())
609 		return;
610 
611 	ar933x_console_ports[up->port.line] = up;
612 }
613 
614 static struct uart_driver ar933x_uart_driver = {
615 	.owner		= THIS_MODULE,
616 	.driver_name	= DRIVER_NAME,
617 	.dev_name	= "ttyATH",
618 	.nr		= CONFIG_SERIAL_AR933X_NR_UARTS,
619 	.cons		= NULL, /* filled in runtime */
620 };
621 
622 static int ar933x_uart_probe(struct platform_device *pdev)
623 {
624 	struct ar933x_uart_port *up;
625 	struct uart_port *port;
626 	struct resource *mem_res;
627 	struct resource *irq_res;
628 	struct device_node *np;
629 	unsigned int baud;
630 	int id;
631 	int ret;
632 
633 	np = pdev->dev.of_node;
634 	if (config_enabled(CONFIG_OF) && np) {
635 		id = of_alias_get_id(np, "serial");
636 		if (id < 0) {
637 			dev_err(&pdev->dev, "unable to get alias id, err=%d\n",
638 				id);
639 			return id;
640 		}
641 	} else {
642 		id = pdev->id;
643 		if (id == -1)
644 			id = 0;
645 	}
646 
647 	if (id > CONFIG_SERIAL_AR933X_NR_UARTS)
648 		return -EINVAL;
649 
650 	irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
651 	if (!irq_res) {
652 		dev_err(&pdev->dev, "no IRQ resource\n");
653 		return -EINVAL;
654 	}
655 
656 	up = devm_kzalloc(&pdev->dev, sizeof(struct ar933x_uart_port),
657 			  GFP_KERNEL);
658 	if (!up)
659 		return -ENOMEM;
660 
661 	up->clk = devm_clk_get(&pdev->dev, "uart");
662 	if (IS_ERR(up->clk)) {
663 		dev_err(&pdev->dev, "unable to get UART clock\n");
664 		return PTR_ERR(up->clk);
665 	}
666 
667 	port = &up->port;
668 
669 	mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
670 	port->membase = devm_ioremap_resource(&pdev->dev, mem_res);
671 	if (IS_ERR(port->membase))
672 		return PTR_ERR(port->membase);
673 
674 	ret = clk_prepare_enable(up->clk);
675 	if (ret)
676 		return ret;
677 
678 	port->uartclk = clk_get_rate(up->clk);
679 	if (!port->uartclk) {
680 		ret = -EINVAL;
681 		goto err_disable_clk;
682 	}
683 
684 	port->mapbase = mem_res->start;
685 	port->line = id;
686 	port->irq = irq_res->start;
687 	port->dev = &pdev->dev;
688 	port->type = PORT_AR933X;
689 	port->iotype = UPIO_MEM32;
690 
691 	port->regshift = 2;
692 	port->fifosize = AR933X_UART_FIFO_SIZE;
693 	port->ops = &ar933x_uart_ops;
694 
695 	baud = ar933x_uart_get_baud(port->uartclk, AR933X_UART_MAX_SCALE, 1);
696 	up->min_baud = max_t(unsigned int, baud, AR933X_UART_MIN_BAUD);
697 
698 	baud = ar933x_uart_get_baud(port->uartclk, 0, AR933X_UART_MAX_STEP);
699 	up->max_baud = min_t(unsigned int, baud, AR933X_UART_MAX_BAUD);
700 
701 	ar933x_uart_add_console_port(up);
702 
703 	ret = uart_add_one_port(&ar933x_uart_driver, &up->port);
704 	if (ret)
705 		goto err_disable_clk;
706 
707 	platform_set_drvdata(pdev, up);
708 	return 0;
709 
710 err_disable_clk:
711 	clk_disable_unprepare(up->clk);
712 	return ret;
713 }
714 
715 static int ar933x_uart_remove(struct platform_device *pdev)
716 {
717 	struct ar933x_uart_port *up;
718 
719 	up = platform_get_drvdata(pdev);
720 
721 	if (up) {
722 		uart_remove_one_port(&ar933x_uart_driver, &up->port);
723 		clk_disable_unprepare(up->clk);
724 	}
725 
726 	return 0;
727 }
728 
729 #ifdef CONFIG_OF
730 static const struct of_device_id ar933x_uart_of_ids[] = {
731 	{ .compatible = "qca,ar9330-uart" },
732 	{},
733 };
734 MODULE_DEVICE_TABLE(of, ar933x_uart_of_ids);
735 #endif
736 
737 static struct platform_driver ar933x_uart_platform_driver = {
738 	.probe		= ar933x_uart_probe,
739 	.remove		= ar933x_uart_remove,
740 	.driver		= {
741 		.name		= DRIVER_NAME,
742 		.owner		= THIS_MODULE,
743 		.of_match_table = of_match_ptr(ar933x_uart_of_ids),
744 	},
745 };
746 
747 static int __init ar933x_uart_init(void)
748 {
749 	int ret;
750 
751 	if (ar933x_uart_console_enabled())
752 		ar933x_uart_driver.cons = &ar933x_uart_console;
753 
754 	ret = uart_register_driver(&ar933x_uart_driver);
755 	if (ret)
756 		goto err_out;
757 
758 	ret = platform_driver_register(&ar933x_uart_platform_driver);
759 	if (ret)
760 		goto err_unregister_uart_driver;
761 
762 	return 0;
763 
764 err_unregister_uart_driver:
765 	uart_unregister_driver(&ar933x_uart_driver);
766 err_out:
767 	return ret;
768 }
769 
770 static void __exit ar933x_uart_exit(void)
771 {
772 	platform_driver_unregister(&ar933x_uart_platform_driver);
773 	uart_unregister_driver(&ar933x_uart_driver);
774 }
775 
776 module_init(ar933x_uart_init);
777 module_exit(ar933x_uart_exit);
778 
779 MODULE_DESCRIPTION("Atheros AR933X UART driver");
780 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
781 MODULE_LICENSE("GPL v2");
782 MODULE_ALIAS("platform:" DRIVER_NAME);
783