xref: /openbmc/linux/drivers/tty/serial/ar933x_uart.c (revision f35e839a)
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/tty.h>
21 #include <linux/tty_flip.h>
22 #include <linux/serial_core.h>
23 #include <linux/serial.h>
24 #include <linux/slab.h>
25 #include <linux/io.h>
26 #include <linux/irq.h>
27 
28 #include <asm/div64.h>
29 
30 #include <asm/mach-ath79/ar933x_uart.h>
31 #include <asm/mach-ath79/ar933x_uart_platform.h>
32 
33 #define DRIVER_NAME "ar933x-uart"
34 
35 #define AR933X_UART_MAX_SCALE	0xff
36 #define AR933X_UART_MAX_STEP	0xffff
37 
38 #define AR933X_UART_MIN_BAUD	300
39 #define AR933X_UART_MAX_BAUD	3000000
40 
41 #define AR933X_DUMMY_STATUS_RD	0x01
42 
43 static struct uart_driver ar933x_uart_driver;
44 
45 struct ar933x_uart_port {
46 	struct uart_port	port;
47 	unsigned int		ier;	/* shadow Interrupt Enable Register */
48 	unsigned int		min_baud;
49 	unsigned int		max_baud;
50 };
51 
52 static inline unsigned int ar933x_uart_read(struct ar933x_uart_port *up,
53 					    int offset)
54 {
55 	return readl(up->port.membase + offset);
56 }
57 
58 static inline void ar933x_uart_write(struct ar933x_uart_port *up,
59 				     int offset, unsigned int value)
60 {
61 	writel(value, up->port.membase + offset);
62 }
63 
64 static inline void ar933x_uart_rmw(struct ar933x_uart_port *up,
65 				  unsigned int offset,
66 				  unsigned int mask,
67 				  unsigned int val)
68 {
69 	unsigned int t;
70 
71 	t = ar933x_uart_read(up, offset);
72 	t &= ~mask;
73 	t |= val;
74 	ar933x_uart_write(up, offset, t);
75 }
76 
77 static inline void ar933x_uart_rmw_set(struct ar933x_uart_port *up,
78 				       unsigned int offset,
79 				       unsigned int val)
80 {
81 	ar933x_uart_rmw(up, offset, 0, val);
82 }
83 
84 static inline void ar933x_uart_rmw_clear(struct ar933x_uart_port *up,
85 					 unsigned int offset,
86 					 unsigned int val)
87 {
88 	ar933x_uart_rmw(up, offset, val, 0);
89 }
90 
91 static inline void ar933x_uart_start_tx_interrupt(struct ar933x_uart_port *up)
92 {
93 	up->ier |= AR933X_UART_INT_TX_EMPTY;
94 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
95 }
96 
97 static inline void ar933x_uart_stop_tx_interrupt(struct ar933x_uart_port *up)
98 {
99 	up->ier &= ~AR933X_UART_INT_TX_EMPTY;
100 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
101 }
102 
103 static inline void ar933x_uart_putc(struct ar933x_uart_port *up, int ch)
104 {
105 	unsigned int rdata;
106 
107 	rdata = ch & AR933X_UART_DATA_TX_RX_MASK;
108 	rdata |= AR933X_UART_DATA_TX_CSR;
109 	ar933x_uart_write(up, AR933X_UART_DATA_REG, rdata);
110 }
111 
112 static unsigned int ar933x_uart_tx_empty(struct uart_port *port)
113 {
114 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
115 	unsigned long flags;
116 	unsigned int rdata;
117 
118 	spin_lock_irqsave(&up->port.lock, flags);
119 	rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
120 	spin_unlock_irqrestore(&up->port.lock, flags);
121 
122 	return (rdata & AR933X_UART_DATA_TX_CSR) ? 0 : TIOCSER_TEMT;
123 }
124 
125 static unsigned int ar933x_uart_get_mctrl(struct uart_port *port)
126 {
127 	return TIOCM_CAR;
128 }
129 
130 static void ar933x_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
131 {
132 }
133 
134 static void ar933x_uart_start_tx(struct uart_port *port)
135 {
136 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
137 
138 	ar933x_uart_start_tx_interrupt(up);
139 }
140 
141 static void ar933x_uart_stop_tx(struct uart_port *port)
142 {
143 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
144 
145 	ar933x_uart_stop_tx_interrupt(up);
146 }
147 
148 static void ar933x_uart_stop_rx(struct uart_port *port)
149 {
150 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
151 
152 	up->ier &= ~AR933X_UART_INT_RX_VALID;
153 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
154 }
155 
156 static void ar933x_uart_break_ctl(struct uart_port *port, int break_state)
157 {
158 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
159 	unsigned long flags;
160 
161 	spin_lock_irqsave(&up->port.lock, flags);
162 	if (break_state == -1)
163 		ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
164 				    AR933X_UART_CS_TX_BREAK);
165 	else
166 		ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
167 				      AR933X_UART_CS_TX_BREAK);
168 	spin_unlock_irqrestore(&up->port.lock, flags);
169 }
170 
171 static void ar933x_uart_enable_ms(struct uart_port *port)
172 {
173 }
174 
175 /*
176  * baudrate = (clk / (scale + 1)) * (step * (1 / 2^17))
177  */
178 static unsigned long ar933x_uart_get_baud(unsigned int clk,
179 					  unsigned int scale,
180 					  unsigned int step)
181 {
182 	u64 t;
183 	u32 div;
184 
185 	div = (2 << 16) * (scale + 1);
186 	t = clk;
187 	t *= step;
188 	t += (div / 2);
189 	do_div(t, div);
190 
191 	return t;
192 }
193 
194 static void ar933x_uart_get_scale_step(unsigned int clk,
195 				       unsigned int baud,
196 				       unsigned int *scale,
197 				       unsigned int *step)
198 {
199 	unsigned int tscale;
200 	long min_diff;
201 
202 	*scale = 0;
203 	*step = 0;
204 
205 	min_diff = baud;
206 	for (tscale = 0; tscale < AR933X_UART_MAX_SCALE; tscale++) {
207 		u64 tstep;
208 		int diff;
209 
210 		tstep = baud * (tscale + 1);
211 		tstep *= (2 << 16);
212 		do_div(tstep, clk);
213 
214 		if (tstep > AR933X_UART_MAX_STEP)
215 			break;
216 
217 		diff = abs(ar933x_uart_get_baud(clk, tscale, tstep) - baud);
218 		if (diff < min_diff) {
219 			min_diff = diff;
220 			*scale = tscale;
221 			*step = tstep;
222 		}
223 	}
224 }
225 
226 static void ar933x_uart_set_termios(struct uart_port *port,
227 				    struct ktermios *new,
228 				    struct ktermios *old)
229 {
230 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
231 	unsigned int cs;
232 	unsigned long flags;
233 	unsigned int baud, scale, step;
234 
235 	/* Only CS8 is supported */
236 	new->c_cflag &= ~CSIZE;
237 	new->c_cflag |= CS8;
238 
239 	/* Only one stop bit is supported */
240 	new->c_cflag &= ~CSTOPB;
241 
242 	cs = 0;
243 	if (new->c_cflag & PARENB) {
244 		if (!(new->c_cflag & PARODD))
245 			cs |= AR933X_UART_CS_PARITY_EVEN;
246 		else
247 			cs |= AR933X_UART_CS_PARITY_ODD;
248 	} else {
249 		cs |= AR933X_UART_CS_PARITY_NONE;
250 	}
251 
252 	/* Mark/space parity is not supported */
253 	new->c_cflag &= ~CMSPAR;
254 
255 	baud = uart_get_baud_rate(port, new, old, up->min_baud, up->max_baud);
256 	ar933x_uart_get_scale_step(port->uartclk, baud, &scale, &step);
257 
258 	/*
259 	 * Ok, we're now changing the port state. Do it with
260 	 * interrupts disabled.
261 	 */
262 	spin_lock_irqsave(&up->port.lock, flags);
263 
264 	/* disable the UART */
265 	ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
266 		      AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S);
267 
268 	/* Update the per-port timeout. */
269 	uart_update_timeout(port, new->c_cflag, baud);
270 
271 	up->port.ignore_status_mask = 0;
272 
273 	/* ignore all characters if CREAD is not set */
274 	if ((new->c_cflag & CREAD) == 0)
275 		up->port.ignore_status_mask |= AR933X_DUMMY_STATUS_RD;
276 
277 	ar933x_uart_write(up, AR933X_UART_CLOCK_REG,
278 			  scale << AR933X_UART_CLOCK_SCALE_S | step);
279 
280 	/* setup configuration register */
281 	ar933x_uart_rmw(up, AR933X_UART_CS_REG, AR933X_UART_CS_PARITY_M, cs);
282 
283 	/* enable host interrupt */
284 	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
285 			    AR933X_UART_CS_HOST_INT_EN);
286 
287 	/* reenable the UART */
288 	ar933x_uart_rmw(up, AR933X_UART_CS_REG,
289 			AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S,
290 			AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S);
291 
292 	spin_unlock_irqrestore(&up->port.lock, flags);
293 
294 	if (tty_termios_baud_rate(new))
295 		tty_termios_encode_baud_rate(new, baud, baud);
296 }
297 
298 static void ar933x_uart_rx_chars(struct ar933x_uart_port *up)
299 {
300 	struct tty_port *port = &up->port.state->port;
301 	int max_count = 256;
302 
303 	do {
304 		unsigned int rdata;
305 		unsigned char ch;
306 
307 		rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
308 		if ((rdata & AR933X_UART_DATA_RX_CSR) == 0)
309 			break;
310 
311 		/* remove the character from the FIFO */
312 		ar933x_uart_write(up, AR933X_UART_DATA_REG,
313 				  AR933X_UART_DATA_RX_CSR);
314 
315 		up->port.icount.rx++;
316 		ch = rdata & AR933X_UART_DATA_TX_RX_MASK;
317 
318 		if (uart_handle_sysrq_char(&up->port, ch))
319 			continue;
320 
321 		if ((up->port.ignore_status_mask & AR933X_DUMMY_STATUS_RD) == 0)
322 			tty_insert_flip_char(port, ch, TTY_NORMAL);
323 	} while (max_count-- > 0);
324 
325 	tty_flip_buffer_push(port);
326 }
327 
328 static void ar933x_uart_tx_chars(struct ar933x_uart_port *up)
329 {
330 	struct circ_buf *xmit = &up->port.state->xmit;
331 	int count;
332 
333 	if (uart_tx_stopped(&up->port))
334 		return;
335 
336 	count = up->port.fifosize;
337 	do {
338 		unsigned int rdata;
339 
340 		rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
341 		if ((rdata & AR933X_UART_DATA_TX_CSR) == 0)
342 			break;
343 
344 		if (up->port.x_char) {
345 			ar933x_uart_putc(up, up->port.x_char);
346 			up->port.icount.tx++;
347 			up->port.x_char = 0;
348 			continue;
349 		}
350 
351 		if (uart_circ_empty(xmit))
352 			break;
353 
354 		ar933x_uart_putc(up, xmit->buf[xmit->tail]);
355 
356 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
357 		up->port.icount.tx++;
358 	} while (--count > 0);
359 
360 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
361 		uart_write_wakeup(&up->port);
362 
363 	if (!uart_circ_empty(xmit))
364 		ar933x_uart_start_tx_interrupt(up);
365 }
366 
367 static irqreturn_t ar933x_uart_interrupt(int irq, void *dev_id)
368 {
369 	struct ar933x_uart_port *up = dev_id;
370 	unsigned int status;
371 
372 	status = ar933x_uart_read(up, AR933X_UART_CS_REG);
373 	if ((status & AR933X_UART_CS_HOST_INT) == 0)
374 		return IRQ_NONE;
375 
376 	spin_lock(&up->port.lock);
377 
378 	status = ar933x_uart_read(up, AR933X_UART_INT_REG);
379 	status &= ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
380 
381 	if (status & AR933X_UART_INT_RX_VALID) {
382 		ar933x_uart_write(up, AR933X_UART_INT_REG,
383 				  AR933X_UART_INT_RX_VALID);
384 		ar933x_uart_rx_chars(up);
385 	}
386 
387 	if (status & AR933X_UART_INT_TX_EMPTY) {
388 		ar933x_uart_write(up, AR933X_UART_INT_REG,
389 				  AR933X_UART_INT_TX_EMPTY);
390 		ar933x_uart_stop_tx_interrupt(up);
391 		ar933x_uart_tx_chars(up);
392 	}
393 
394 	spin_unlock(&up->port.lock);
395 
396 	return IRQ_HANDLED;
397 }
398 
399 static int ar933x_uart_startup(struct uart_port *port)
400 {
401 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
402 	unsigned long flags;
403 	int ret;
404 
405 	ret = request_irq(up->port.irq, ar933x_uart_interrupt,
406 			  up->port.irqflags, dev_name(up->port.dev), up);
407 	if (ret)
408 		return ret;
409 
410 	spin_lock_irqsave(&up->port.lock, flags);
411 
412 	/* Enable HOST interrupts */
413 	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
414 			    AR933X_UART_CS_HOST_INT_EN);
415 
416 	/* Enable RX interrupts */
417 	up->ier = AR933X_UART_INT_RX_VALID;
418 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
419 
420 	spin_unlock_irqrestore(&up->port.lock, flags);
421 
422 	return 0;
423 }
424 
425 static void ar933x_uart_shutdown(struct uart_port *port)
426 {
427 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
428 
429 	/* Disable all interrupts */
430 	up->ier = 0;
431 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
432 
433 	/* Disable break condition */
434 	ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
435 			      AR933X_UART_CS_TX_BREAK);
436 
437 	free_irq(up->port.irq, up);
438 }
439 
440 static const char *ar933x_uart_type(struct uart_port *port)
441 {
442 	return (port->type == PORT_AR933X) ? "AR933X UART" : NULL;
443 }
444 
445 static void ar933x_uart_release_port(struct uart_port *port)
446 {
447 	/* Nothing to release ... */
448 }
449 
450 static int ar933x_uart_request_port(struct uart_port *port)
451 {
452 	/* UARTs always present */
453 	return 0;
454 }
455 
456 static void ar933x_uart_config_port(struct uart_port *port, int flags)
457 {
458 	if (flags & UART_CONFIG_TYPE)
459 		port->type = PORT_AR933X;
460 }
461 
462 static int ar933x_uart_verify_port(struct uart_port *port,
463 				   struct serial_struct *ser)
464 {
465 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
466 
467 	if (ser->type != PORT_UNKNOWN &&
468 	    ser->type != PORT_AR933X)
469 		return -EINVAL;
470 
471 	if (ser->irq < 0 || ser->irq >= NR_IRQS)
472 		return -EINVAL;
473 
474 	if (ser->baud_base < up->min_baud ||
475 	    ser->baud_base > up->max_baud)
476 		return -EINVAL;
477 
478 	return 0;
479 }
480 
481 static struct uart_ops ar933x_uart_ops = {
482 	.tx_empty	= ar933x_uart_tx_empty,
483 	.set_mctrl	= ar933x_uart_set_mctrl,
484 	.get_mctrl	= ar933x_uart_get_mctrl,
485 	.stop_tx	= ar933x_uart_stop_tx,
486 	.start_tx	= ar933x_uart_start_tx,
487 	.stop_rx	= ar933x_uart_stop_rx,
488 	.enable_ms	= ar933x_uart_enable_ms,
489 	.break_ctl	= ar933x_uart_break_ctl,
490 	.startup	= ar933x_uart_startup,
491 	.shutdown	= ar933x_uart_shutdown,
492 	.set_termios	= ar933x_uart_set_termios,
493 	.type		= ar933x_uart_type,
494 	.release_port	= ar933x_uart_release_port,
495 	.request_port	= ar933x_uart_request_port,
496 	.config_port	= ar933x_uart_config_port,
497 	.verify_port	= ar933x_uart_verify_port,
498 };
499 
500 #ifdef CONFIG_SERIAL_AR933X_CONSOLE
501 
502 static struct ar933x_uart_port *
503 ar933x_console_ports[CONFIG_SERIAL_AR933X_NR_UARTS];
504 
505 static void ar933x_uart_wait_xmitr(struct ar933x_uart_port *up)
506 {
507 	unsigned int status;
508 	unsigned int timeout = 60000;
509 
510 	/* Wait up to 60ms for the character(s) to be sent. */
511 	do {
512 		status = ar933x_uart_read(up, AR933X_UART_DATA_REG);
513 		if (--timeout == 0)
514 			break;
515 		udelay(1);
516 	} while ((status & AR933X_UART_DATA_TX_CSR) == 0);
517 }
518 
519 static void ar933x_uart_console_putchar(struct uart_port *port, int ch)
520 {
521 	struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
522 
523 	ar933x_uart_wait_xmitr(up);
524 	ar933x_uart_putc(up, ch);
525 }
526 
527 static void ar933x_uart_console_write(struct console *co, const char *s,
528 				      unsigned int count)
529 {
530 	struct ar933x_uart_port *up = ar933x_console_ports[co->index];
531 	unsigned long flags;
532 	unsigned int int_en;
533 	int locked = 1;
534 
535 	local_irq_save(flags);
536 
537 	if (up->port.sysrq)
538 		locked = 0;
539 	else if (oops_in_progress)
540 		locked = spin_trylock(&up->port.lock);
541 	else
542 		spin_lock(&up->port.lock);
543 
544 	/*
545 	 * First save the IER then disable the interrupts
546 	 */
547 	int_en = ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
548 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0);
549 
550 	uart_console_write(&up->port, s, count, ar933x_uart_console_putchar);
551 
552 	/*
553 	 * Finally, wait for transmitter to become empty
554 	 * and restore the IER
555 	 */
556 	ar933x_uart_wait_xmitr(up);
557 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, int_en);
558 
559 	ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_ALLINTS);
560 
561 	if (locked)
562 		spin_unlock(&up->port.lock);
563 
564 	local_irq_restore(flags);
565 }
566 
567 static int ar933x_uart_console_setup(struct console *co, char *options)
568 {
569 	struct ar933x_uart_port *up;
570 	int baud = 115200;
571 	int bits = 8;
572 	int parity = 'n';
573 	int flow = 'n';
574 
575 	if (co->index < 0 || co->index >= CONFIG_SERIAL_AR933X_NR_UARTS)
576 		return -EINVAL;
577 
578 	up = ar933x_console_ports[co->index];
579 	if (!up)
580 		return -ENODEV;
581 
582 	if (options)
583 		uart_parse_options(options, &baud, &parity, &bits, &flow);
584 
585 	return uart_set_options(&up->port, co, baud, parity, bits, flow);
586 }
587 
588 static struct console ar933x_uart_console = {
589 	.name		= "ttyATH",
590 	.write		= ar933x_uart_console_write,
591 	.device		= uart_console_device,
592 	.setup		= ar933x_uart_console_setup,
593 	.flags		= CON_PRINTBUFFER,
594 	.index		= -1,
595 	.data		= &ar933x_uart_driver,
596 };
597 
598 static void ar933x_uart_add_console_port(struct ar933x_uart_port *up)
599 {
600 	ar933x_console_ports[up->port.line] = up;
601 }
602 
603 #define AR933X_SERIAL_CONSOLE	(&ar933x_uart_console)
604 
605 #else
606 
607 static inline void ar933x_uart_add_console_port(struct ar933x_uart_port *up) {}
608 
609 #define AR933X_SERIAL_CONSOLE	NULL
610 
611 #endif /* CONFIG_SERIAL_AR933X_CONSOLE */
612 
613 static struct uart_driver ar933x_uart_driver = {
614 	.owner		= THIS_MODULE,
615 	.driver_name	= DRIVER_NAME,
616 	.dev_name	= "ttyATH",
617 	.nr		= CONFIG_SERIAL_AR933X_NR_UARTS,
618 	.cons		= AR933X_SERIAL_CONSOLE,
619 };
620 
621 static int ar933x_uart_probe(struct platform_device *pdev)
622 {
623 	struct ar933x_uart_platform_data *pdata;
624 	struct ar933x_uart_port *up;
625 	struct uart_port *port;
626 	struct resource *mem_res;
627 	struct resource *irq_res;
628 	unsigned int baud;
629 	int id;
630 	int ret;
631 
632 	pdata = pdev->dev.platform_data;
633 	if (!pdata)
634 		return -EINVAL;
635 
636 	id = pdev->id;
637 	if (id == -1)
638 		id = 0;
639 
640 	if (id > CONFIG_SERIAL_AR933X_NR_UARTS)
641 		return -EINVAL;
642 
643 	mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
644 	if (!mem_res) {
645 		dev_err(&pdev->dev, "no MEM resource\n");
646 		return -EINVAL;
647 	}
648 
649 	irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
650 	if (!irq_res) {
651 		dev_err(&pdev->dev, "no IRQ resource\n");
652 		return -EINVAL;
653 	}
654 
655 	up = kzalloc(sizeof(struct ar933x_uart_port), GFP_KERNEL);
656 	if (!up)
657 		return -ENOMEM;
658 
659 	port = &up->port;
660 	port->mapbase = mem_res->start;
661 
662 	port->membase = ioremap(mem_res->start, AR933X_UART_REGS_SIZE);
663 	if (!port->membase) {
664 		ret = -ENOMEM;
665 		goto err_free_up;
666 	}
667 
668 	port->line = id;
669 	port->irq = irq_res->start;
670 	port->dev = &pdev->dev;
671 	port->type = PORT_AR933X;
672 	port->iotype = UPIO_MEM32;
673 	port->uartclk = pdata->uartclk;
674 
675 	port->regshift = 2;
676 	port->fifosize = AR933X_UART_FIFO_SIZE;
677 	port->ops = &ar933x_uart_ops;
678 
679 	baud = ar933x_uart_get_baud(port->uartclk, AR933X_UART_MAX_SCALE, 1);
680 	up->min_baud = max_t(unsigned int, baud, AR933X_UART_MIN_BAUD);
681 
682 	baud = ar933x_uart_get_baud(port->uartclk, 0, AR933X_UART_MAX_STEP);
683 	up->max_baud = min_t(unsigned int, baud, AR933X_UART_MAX_BAUD);
684 
685 	ar933x_uart_add_console_port(up);
686 
687 	ret = uart_add_one_port(&ar933x_uart_driver, &up->port);
688 	if (ret)
689 		goto err_unmap;
690 
691 	platform_set_drvdata(pdev, up);
692 	return 0;
693 
694 err_unmap:
695 	iounmap(up->port.membase);
696 err_free_up:
697 	kfree(up);
698 	return ret;
699 }
700 
701 static int ar933x_uart_remove(struct platform_device *pdev)
702 {
703 	struct ar933x_uart_port *up;
704 
705 	up = platform_get_drvdata(pdev);
706 	platform_set_drvdata(pdev, NULL);
707 
708 	if (up) {
709 		uart_remove_one_port(&ar933x_uart_driver, &up->port);
710 		iounmap(up->port.membase);
711 		kfree(up);
712 	}
713 
714 	return 0;
715 }
716 
717 static struct platform_driver ar933x_uart_platform_driver = {
718 	.probe		= ar933x_uart_probe,
719 	.remove		= ar933x_uart_remove,
720 	.driver		= {
721 		.name		= DRIVER_NAME,
722 		.owner		= THIS_MODULE,
723 	},
724 };
725 
726 static int __init ar933x_uart_init(void)
727 {
728 	int ret;
729 
730 	ar933x_uart_driver.nr = CONFIG_SERIAL_AR933X_NR_UARTS;
731 	ret = uart_register_driver(&ar933x_uart_driver);
732 	if (ret)
733 		goto err_out;
734 
735 	ret = platform_driver_register(&ar933x_uart_platform_driver);
736 	if (ret)
737 		goto err_unregister_uart_driver;
738 
739 	return 0;
740 
741 err_unregister_uart_driver:
742 	uart_unregister_driver(&ar933x_uart_driver);
743 err_out:
744 	return ret;
745 }
746 
747 static void __exit ar933x_uart_exit(void)
748 {
749 	platform_driver_unregister(&ar933x_uart_platform_driver);
750 	uart_unregister_driver(&ar933x_uart_driver);
751 }
752 
753 module_init(ar933x_uart_init);
754 module_exit(ar933x_uart_exit);
755 
756 MODULE_DESCRIPTION("Atheros AR933X UART driver");
757 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
758 MODULE_LICENSE("GPL v2");
759 MODULE_ALIAS("platform:" DRIVER_NAME);
760