xref: /openbmc/linux/drivers/tty/serial/amba-pl010.c (revision 7a010c3c)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *  Driver for AMBA serial ports
4  *
5  *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
6  *
7  *  Copyright 1999 ARM Limited
8  *  Copyright (C) 2000 Deep Blue Solutions Ltd.
9  *
10  * This is a generic driver for ARM AMBA-type serial ports.  They
11  * have a lot of 16550-like features, but are not register compatible.
12  * Note that although they do have CTS, DCD and DSR inputs, they do
13  * not have an RI input, nor do they have DTR or RTS outputs.  If
14  * required, these have to be supplied via some other means (eg, GPIO)
15  * and hooked into this driver.
16  */
17 
18 #include <linux/module.h>
19 #include <linux/ioport.h>
20 #include <linux/init.h>
21 #include <linux/console.h>
22 #include <linux/sysrq.h>
23 #include <linux/device.h>
24 #include <linux/tty.h>
25 #include <linux/tty_flip.h>
26 #include <linux/serial_core.h>
27 #include <linux/serial.h>
28 #include <linux/amba/bus.h>
29 #include <linux/amba/serial.h>
30 #include <linux/clk.h>
31 #include <linux/slab.h>
32 #include <linux/io.h>
33 
34 #define UART_NR		8
35 
36 #define SERIAL_AMBA_MAJOR	204
37 #define SERIAL_AMBA_MINOR	16
38 #define SERIAL_AMBA_NR		UART_NR
39 
40 #define AMBA_ISR_PASS_LIMIT	256
41 
42 #define UART_RX_DATA(s)		(((s) & UART01x_FR_RXFE) == 0)
43 #define UART_TX_READY(s)	(((s) & UART01x_FR_TXFF) == 0)
44 
45 #define UART_DUMMY_RSR_RX	256
46 #define UART_PORT_SIZE		64
47 
48 /*
49  * We wrap our port structure around the generic uart_port.
50  */
51 struct uart_amba_port {
52 	struct uart_port	port;
53 	struct clk		*clk;
54 	struct amba_device	*dev;
55 	struct amba_pl010_data	*data;
56 	unsigned int		old_status;
57 };
58 
59 static void pl010_stop_tx(struct uart_port *port)
60 {
61 	struct uart_amba_port *uap =
62 		container_of(port, struct uart_amba_port, port);
63 	unsigned int cr;
64 
65 	cr = readb(uap->port.membase + UART010_CR);
66 	cr &= ~UART010_CR_TIE;
67 	writel(cr, uap->port.membase + UART010_CR);
68 }
69 
70 static void pl010_start_tx(struct uart_port *port)
71 {
72 	struct uart_amba_port *uap =
73 		container_of(port, struct uart_amba_port, port);
74 	unsigned int cr;
75 
76 	cr = readb(uap->port.membase + UART010_CR);
77 	cr |= UART010_CR_TIE;
78 	writel(cr, uap->port.membase + UART010_CR);
79 }
80 
81 static void pl010_stop_rx(struct uart_port *port)
82 {
83 	struct uart_amba_port *uap =
84 		container_of(port, struct uart_amba_port, port);
85 	unsigned int cr;
86 
87 	cr = readb(uap->port.membase + UART010_CR);
88 	cr &= ~(UART010_CR_RIE | UART010_CR_RTIE);
89 	writel(cr, uap->port.membase + UART010_CR);
90 }
91 
92 static void pl010_disable_ms(struct uart_port *port)
93 {
94 	struct uart_amba_port *uap = (struct uart_amba_port *)port;
95 	unsigned int cr;
96 
97 	cr = readb(uap->port.membase + UART010_CR);
98 	cr &= ~UART010_CR_MSIE;
99 	writel(cr, uap->port.membase + UART010_CR);
100 }
101 
102 static void pl010_enable_ms(struct uart_port *port)
103 {
104 	struct uart_amba_port *uap =
105 		container_of(port, struct uart_amba_port, port);
106 	unsigned int cr;
107 
108 	cr = readb(uap->port.membase + UART010_CR);
109 	cr |= UART010_CR_MSIE;
110 	writel(cr, uap->port.membase + UART010_CR);
111 }
112 
113 static void pl010_rx_chars(struct uart_amba_port *uap)
114 {
115 	unsigned int status, ch, flag, rsr, max_count = 256;
116 
117 	status = readb(uap->port.membase + UART01x_FR);
118 	while (UART_RX_DATA(status) && max_count--) {
119 		ch = readb(uap->port.membase + UART01x_DR);
120 		flag = TTY_NORMAL;
121 
122 		uap->port.icount.rx++;
123 
124 		/*
125 		 * Note that the error handling code is
126 		 * out of the main execution path
127 		 */
128 		rsr = readb(uap->port.membase + UART01x_RSR) | UART_DUMMY_RSR_RX;
129 		if (unlikely(rsr & UART01x_RSR_ANY)) {
130 			writel(0, uap->port.membase + UART01x_ECR);
131 
132 			if (rsr & UART01x_RSR_BE) {
133 				rsr &= ~(UART01x_RSR_FE | UART01x_RSR_PE);
134 				uap->port.icount.brk++;
135 				if (uart_handle_break(&uap->port))
136 					goto ignore_char;
137 			} else if (rsr & UART01x_RSR_PE)
138 				uap->port.icount.parity++;
139 			else if (rsr & UART01x_RSR_FE)
140 				uap->port.icount.frame++;
141 			if (rsr & UART01x_RSR_OE)
142 				uap->port.icount.overrun++;
143 
144 			rsr &= uap->port.read_status_mask;
145 
146 			if (rsr & UART01x_RSR_BE)
147 				flag = TTY_BREAK;
148 			else if (rsr & UART01x_RSR_PE)
149 				flag = TTY_PARITY;
150 			else if (rsr & UART01x_RSR_FE)
151 				flag = TTY_FRAME;
152 		}
153 
154 		if (uart_handle_sysrq_char(&uap->port, ch))
155 			goto ignore_char;
156 
157 		uart_insert_char(&uap->port, rsr, UART01x_RSR_OE, ch, flag);
158 
159 	ignore_char:
160 		status = readb(uap->port.membase + UART01x_FR);
161 	}
162 	tty_flip_buffer_push(&uap->port.state->port);
163 }
164 
165 static void pl010_tx_chars(struct uart_amba_port *uap)
166 {
167 	struct circ_buf *xmit = &uap->port.state->xmit;
168 	int count;
169 
170 	if (uap->port.x_char) {
171 		writel(uap->port.x_char, uap->port.membase + UART01x_DR);
172 		uap->port.icount.tx++;
173 		uap->port.x_char = 0;
174 		return;
175 	}
176 	if (uart_circ_empty(xmit) || uart_tx_stopped(&uap->port)) {
177 		pl010_stop_tx(&uap->port);
178 		return;
179 	}
180 
181 	count = uap->port.fifosize >> 1;
182 	do {
183 		writel(xmit->buf[xmit->tail], uap->port.membase + UART01x_DR);
184 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
185 		uap->port.icount.tx++;
186 		if (uart_circ_empty(xmit))
187 			break;
188 	} while (--count > 0);
189 
190 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
191 		uart_write_wakeup(&uap->port);
192 
193 	if (uart_circ_empty(xmit))
194 		pl010_stop_tx(&uap->port);
195 }
196 
197 static void pl010_modem_status(struct uart_amba_port *uap)
198 {
199 	unsigned int status, delta;
200 
201 	writel(0, uap->port.membase + UART010_ICR);
202 
203 	status = readb(uap->port.membase + UART01x_FR) & UART01x_FR_MODEM_ANY;
204 
205 	delta = status ^ uap->old_status;
206 	uap->old_status = status;
207 
208 	if (!delta)
209 		return;
210 
211 	if (delta & UART01x_FR_DCD)
212 		uart_handle_dcd_change(&uap->port, status & UART01x_FR_DCD);
213 
214 	if (delta & UART01x_FR_DSR)
215 		uap->port.icount.dsr++;
216 
217 	if (delta & UART01x_FR_CTS)
218 		uart_handle_cts_change(&uap->port, status & UART01x_FR_CTS);
219 
220 	wake_up_interruptible(&uap->port.state->port.delta_msr_wait);
221 }
222 
223 static irqreturn_t pl010_int(int irq, void *dev_id)
224 {
225 	struct uart_amba_port *uap = dev_id;
226 	unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
227 	int handled = 0;
228 
229 	spin_lock(&uap->port.lock);
230 
231 	status = readb(uap->port.membase + UART010_IIR);
232 	if (status) {
233 		do {
234 			if (status & (UART010_IIR_RTIS | UART010_IIR_RIS))
235 				pl010_rx_chars(uap);
236 			if (status & UART010_IIR_MIS)
237 				pl010_modem_status(uap);
238 			if (status & UART010_IIR_TIS)
239 				pl010_tx_chars(uap);
240 
241 			if (pass_counter-- == 0)
242 				break;
243 
244 			status = readb(uap->port.membase + UART010_IIR);
245 		} while (status & (UART010_IIR_RTIS | UART010_IIR_RIS |
246 				   UART010_IIR_TIS));
247 		handled = 1;
248 	}
249 
250 	spin_unlock(&uap->port.lock);
251 
252 	return IRQ_RETVAL(handled);
253 }
254 
255 static unsigned int pl010_tx_empty(struct uart_port *port)
256 {
257 	struct uart_amba_port *uap =
258 		container_of(port, struct uart_amba_port, port);
259 	unsigned int status = readb(uap->port.membase + UART01x_FR);
260 	return status & UART01x_FR_BUSY ? 0 : TIOCSER_TEMT;
261 }
262 
263 static unsigned int pl010_get_mctrl(struct uart_port *port)
264 {
265 	struct uart_amba_port *uap =
266 		container_of(port, struct uart_amba_port, port);
267 	unsigned int result = 0;
268 	unsigned int status;
269 
270 	status = readb(uap->port.membase + UART01x_FR);
271 	if (status & UART01x_FR_DCD)
272 		result |= TIOCM_CAR;
273 	if (status & UART01x_FR_DSR)
274 		result |= TIOCM_DSR;
275 	if (status & UART01x_FR_CTS)
276 		result |= TIOCM_CTS;
277 
278 	return result;
279 }
280 
281 static void pl010_set_mctrl(struct uart_port *port, unsigned int mctrl)
282 {
283 	struct uart_amba_port *uap =
284 		container_of(port, struct uart_amba_port, port);
285 
286 	if (uap->data)
287 		uap->data->set_mctrl(uap->dev, uap->port.membase, mctrl);
288 }
289 
290 static void pl010_break_ctl(struct uart_port *port, int break_state)
291 {
292 	struct uart_amba_port *uap =
293 		container_of(port, struct uart_amba_port, port);
294 	unsigned long flags;
295 	unsigned int lcr_h;
296 
297 	spin_lock_irqsave(&uap->port.lock, flags);
298 	lcr_h = readb(uap->port.membase + UART010_LCRH);
299 	if (break_state == -1)
300 		lcr_h |= UART01x_LCRH_BRK;
301 	else
302 		lcr_h &= ~UART01x_LCRH_BRK;
303 	writel(lcr_h, uap->port.membase + UART010_LCRH);
304 	spin_unlock_irqrestore(&uap->port.lock, flags);
305 }
306 
307 static int pl010_startup(struct uart_port *port)
308 {
309 	struct uart_amba_port *uap =
310 		container_of(port, struct uart_amba_port, port);
311 	int retval;
312 
313 	/*
314 	 * Try to enable the clock producer.
315 	 */
316 	retval = clk_prepare_enable(uap->clk);
317 	if (retval)
318 		goto out;
319 
320 	uap->port.uartclk = clk_get_rate(uap->clk);
321 
322 	/*
323 	 * Allocate the IRQ
324 	 */
325 	retval = request_irq(uap->port.irq, pl010_int, 0, "uart-pl010", uap);
326 	if (retval)
327 		goto clk_dis;
328 
329 	/*
330 	 * initialise the old status of the modem signals
331 	 */
332 	uap->old_status = readb(uap->port.membase + UART01x_FR) & UART01x_FR_MODEM_ANY;
333 
334 	/*
335 	 * Finally, enable interrupts
336 	 */
337 	writel(UART01x_CR_UARTEN | UART010_CR_RIE | UART010_CR_RTIE,
338 	       uap->port.membase + UART010_CR);
339 
340 	return 0;
341 
342  clk_dis:
343 	clk_disable_unprepare(uap->clk);
344  out:
345 	return retval;
346 }
347 
348 static void pl010_shutdown(struct uart_port *port)
349 {
350 	struct uart_amba_port *uap =
351 		container_of(port, struct uart_amba_port, port);
352 
353 	/*
354 	 * Free the interrupt
355 	 */
356 	free_irq(uap->port.irq, uap);
357 
358 	/*
359 	 * disable all interrupts, disable the port
360 	 */
361 	writel(0, uap->port.membase + UART010_CR);
362 
363 	/* disable break condition and fifos */
364 	writel(readb(uap->port.membase + UART010_LCRH) &
365 		~(UART01x_LCRH_BRK | UART01x_LCRH_FEN),
366 	       uap->port.membase + UART010_LCRH);
367 
368 	/*
369 	 * Shut down the clock producer
370 	 */
371 	clk_disable_unprepare(uap->clk);
372 }
373 
374 static void
375 pl010_set_termios(struct uart_port *port, struct ktermios *termios,
376 		     struct ktermios *old)
377 {
378 	struct uart_amba_port *uap =
379 		container_of(port, struct uart_amba_port, port);
380 	unsigned int lcr_h, old_cr;
381 	unsigned long flags;
382 	unsigned int baud, quot;
383 
384 	/*
385 	 * Ask the core to calculate the divisor for us.
386 	 */
387 	baud = uart_get_baud_rate(port, termios, old, 0, uap->port.uartclk/16);
388 	quot = uart_get_divisor(port, baud);
389 
390 	switch (termios->c_cflag & CSIZE) {
391 	case CS5:
392 		lcr_h = UART01x_LCRH_WLEN_5;
393 		break;
394 	case CS6:
395 		lcr_h = UART01x_LCRH_WLEN_6;
396 		break;
397 	case CS7:
398 		lcr_h = UART01x_LCRH_WLEN_7;
399 		break;
400 	default: // CS8
401 		lcr_h = UART01x_LCRH_WLEN_8;
402 		break;
403 	}
404 	if (termios->c_cflag & CSTOPB)
405 		lcr_h |= UART01x_LCRH_STP2;
406 	if (termios->c_cflag & PARENB) {
407 		lcr_h |= UART01x_LCRH_PEN;
408 		if (!(termios->c_cflag & PARODD))
409 			lcr_h |= UART01x_LCRH_EPS;
410 	}
411 	if (uap->port.fifosize > 1)
412 		lcr_h |= UART01x_LCRH_FEN;
413 
414 	spin_lock_irqsave(&uap->port.lock, flags);
415 
416 	/*
417 	 * Update the per-port timeout.
418 	 */
419 	uart_update_timeout(port, termios->c_cflag, baud);
420 
421 	uap->port.read_status_mask = UART01x_RSR_OE;
422 	if (termios->c_iflag & INPCK)
423 		uap->port.read_status_mask |= UART01x_RSR_FE | UART01x_RSR_PE;
424 	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
425 		uap->port.read_status_mask |= UART01x_RSR_BE;
426 
427 	/*
428 	 * Characters to ignore
429 	 */
430 	uap->port.ignore_status_mask = 0;
431 	if (termios->c_iflag & IGNPAR)
432 		uap->port.ignore_status_mask |= UART01x_RSR_FE | UART01x_RSR_PE;
433 	if (termios->c_iflag & IGNBRK) {
434 		uap->port.ignore_status_mask |= UART01x_RSR_BE;
435 		/*
436 		 * If we're ignoring parity and break indicators,
437 		 * ignore overruns too (for real raw support).
438 		 */
439 		if (termios->c_iflag & IGNPAR)
440 			uap->port.ignore_status_mask |= UART01x_RSR_OE;
441 	}
442 
443 	/*
444 	 * Ignore all characters if CREAD is not set.
445 	 */
446 	if ((termios->c_cflag & CREAD) == 0)
447 		uap->port.ignore_status_mask |= UART_DUMMY_RSR_RX;
448 
449 	/* first, disable everything */
450 	old_cr = readb(uap->port.membase + UART010_CR) & ~UART010_CR_MSIE;
451 
452 	if (UART_ENABLE_MS(port, termios->c_cflag))
453 		old_cr |= UART010_CR_MSIE;
454 
455 	writel(0, uap->port.membase + UART010_CR);
456 
457 	/* Set baud rate */
458 	quot -= 1;
459 	writel((quot & 0xf00) >> 8, uap->port.membase + UART010_LCRM);
460 	writel(quot & 0xff, uap->port.membase + UART010_LCRL);
461 
462 	/*
463 	 * ----------v----------v----------v----------v-----
464 	 * NOTE: MUST BE WRITTEN AFTER UARTLCR_M & UARTLCR_L
465 	 * ----------^----------^----------^----------^-----
466 	 */
467 	writel(lcr_h, uap->port.membase + UART010_LCRH);
468 	writel(old_cr, uap->port.membase + UART010_CR);
469 
470 	spin_unlock_irqrestore(&uap->port.lock, flags);
471 }
472 
473 static void pl010_set_ldisc(struct uart_port *port, struct ktermios *termios)
474 {
475 	if (termios->c_line == N_PPS) {
476 		port->flags |= UPF_HARDPPS_CD;
477 		spin_lock_irq(&port->lock);
478 		pl010_enable_ms(port);
479 		spin_unlock_irq(&port->lock);
480 	} else {
481 		port->flags &= ~UPF_HARDPPS_CD;
482 		if (!UART_ENABLE_MS(port, termios->c_cflag)) {
483 			spin_lock_irq(&port->lock);
484 			pl010_disable_ms(port);
485 			spin_unlock_irq(&port->lock);
486 		}
487 	}
488 }
489 
490 static const char *pl010_type(struct uart_port *port)
491 {
492 	return port->type == PORT_AMBA ? "AMBA" : NULL;
493 }
494 
495 /*
496  * Release the memory region(s) being used by 'port'
497  */
498 static void pl010_release_port(struct uart_port *port)
499 {
500 	release_mem_region(port->mapbase, UART_PORT_SIZE);
501 }
502 
503 /*
504  * Request the memory region(s) being used by 'port'
505  */
506 static int pl010_request_port(struct uart_port *port)
507 {
508 	return request_mem_region(port->mapbase, UART_PORT_SIZE, "uart-pl010")
509 			!= NULL ? 0 : -EBUSY;
510 }
511 
512 /*
513  * Configure/autoconfigure the port.
514  */
515 static void pl010_config_port(struct uart_port *port, int flags)
516 {
517 	if (flags & UART_CONFIG_TYPE) {
518 		port->type = PORT_AMBA;
519 		pl010_request_port(port);
520 	}
521 }
522 
523 /*
524  * verify the new serial_struct (for TIOCSSERIAL).
525  */
526 static int pl010_verify_port(struct uart_port *port, struct serial_struct *ser)
527 {
528 	int ret = 0;
529 	if (ser->type != PORT_UNKNOWN && ser->type != PORT_AMBA)
530 		ret = -EINVAL;
531 	if (ser->irq < 0 || ser->irq >= nr_irqs)
532 		ret = -EINVAL;
533 	if (ser->baud_base < 9600)
534 		ret = -EINVAL;
535 	return ret;
536 }
537 
538 static const struct uart_ops amba_pl010_pops = {
539 	.tx_empty	= pl010_tx_empty,
540 	.set_mctrl	= pl010_set_mctrl,
541 	.get_mctrl	= pl010_get_mctrl,
542 	.stop_tx	= pl010_stop_tx,
543 	.start_tx	= pl010_start_tx,
544 	.stop_rx	= pl010_stop_rx,
545 	.enable_ms	= pl010_enable_ms,
546 	.break_ctl	= pl010_break_ctl,
547 	.startup	= pl010_startup,
548 	.shutdown	= pl010_shutdown,
549 	.set_termios	= pl010_set_termios,
550 	.set_ldisc	= pl010_set_ldisc,
551 	.type		= pl010_type,
552 	.release_port	= pl010_release_port,
553 	.request_port	= pl010_request_port,
554 	.config_port	= pl010_config_port,
555 	.verify_port	= pl010_verify_port,
556 };
557 
558 static struct uart_amba_port *amba_ports[UART_NR];
559 
560 #ifdef CONFIG_SERIAL_AMBA_PL010_CONSOLE
561 
562 static void pl010_console_putchar(struct uart_port *port, int ch)
563 {
564 	struct uart_amba_port *uap =
565 		container_of(port, struct uart_amba_port, port);
566 	unsigned int status;
567 
568 	do {
569 		status = readb(uap->port.membase + UART01x_FR);
570 		barrier();
571 	} while (!UART_TX_READY(status));
572 	writel(ch, uap->port.membase + UART01x_DR);
573 }
574 
575 static void
576 pl010_console_write(struct console *co, const char *s, unsigned int count)
577 {
578 	struct uart_amba_port *uap = amba_ports[co->index];
579 	unsigned int status, old_cr;
580 
581 	clk_enable(uap->clk);
582 
583 	/*
584 	 *	First save the CR then disable the interrupts
585 	 */
586 	old_cr = readb(uap->port.membase + UART010_CR);
587 	writel(UART01x_CR_UARTEN, uap->port.membase + UART010_CR);
588 
589 	uart_console_write(&uap->port, s, count, pl010_console_putchar);
590 
591 	/*
592 	 *	Finally, wait for transmitter to become empty
593 	 *	and restore the TCR
594 	 */
595 	do {
596 		status = readb(uap->port.membase + UART01x_FR);
597 		barrier();
598 	} while (status & UART01x_FR_BUSY);
599 	writel(old_cr, uap->port.membase + UART010_CR);
600 
601 	clk_disable(uap->clk);
602 }
603 
604 static void __init
605 pl010_console_get_options(struct uart_amba_port *uap, int *baud,
606 			     int *parity, int *bits)
607 {
608 	if (readb(uap->port.membase + UART010_CR) & UART01x_CR_UARTEN) {
609 		unsigned int lcr_h, quot;
610 		lcr_h = readb(uap->port.membase + UART010_LCRH);
611 
612 		*parity = 'n';
613 		if (lcr_h & UART01x_LCRH_PEN) {
614 			if (lcr_h & UART01x_LCRH_EPS)
615 				*parity = 'e';
616 			else
617 				*parity = 'o';
618 		}
619 
620 		if ((lcr_h & 0x60) == UART01x_LCRH_WLEN_7)
621 			*bits = 7;
622 		else
623 			*bits = 8;
624 
625 		quot = readb(uap->port.membase + UART010_LCRL) |
626 		       readb(uap->port.membase + UART010_LCRM) << 8;
627 		*baud = uap->port.uartclk / (16 * (quot + 1));
628 	}
629 }
630 
631 static int __init pl010_console_setup(struct console *co, char *options)
632 {
633 	struct uart_amba_port *uap;
634 	int baud = 38400;
635 	int bits = 8;
636 	int parity = 'n';
637 	int flow = 'n';
638 	int ret;
639 
640 	/*
641 	 * Check whether an invalid uart number has been specified, and
642 	 * if so, search for the first available port that does have
643 	 * console support.
644 	 */
645 	if (co->index >= UART_NR)
646 		co->index = 0;
647 	uap = amba_ports[co->index];
648 	if (!uap)
649 		return -ENODEV;
650 
651 	ret = clk_prepare(uap->clk);
652 	if (ret)
653 		return ret;
654 
655 	uap->port.uartclk = clk_get_rate(uap->clk);
656 
657 	if (options)
658 		uart_parse_options(options, &baud, &parity, &bits, &flow);
659 	else
660 		pl010_console_get_options(uap, &baud, &parity, &bits);
661 
662 	return uart_set_options(&uap->port, co, baud, parity, bits, flow);
663 }
664 
665 static struct uart_driver amba_reg;
666 static struct console amba_console = {
667 	.name		= "ttyAM",
668 	.write		= pl010_console_write,
669 	.device		= uart_console_device,
670 	.setup		= pl010_console_setup,
671 	.flags		= CON_PRINTBUFFER,
672 	.index		= -1,
673 	.data		= &amba_reg,
674 };
675 
676 #define AMBA_CONSOLE	&amba_console
677 #else
678 #define AMBA_CONSOLE	NULL
679 #endif
680 
681 static DEFINE_MUTEX(amba_reg_lock);
682 static struct uart_driver amba_reg = {
683 	.owner			= THIS_MODULE,
684 	.driver_name		= "ttyAM",
685 	.dev_name		= "ttyAM",
686 	.major			= SERIAL_AMBA_MAJOR,
687 	.minor			= SERIAL_AMBA_MINOR,
688 	.nr			= UART_NR,
689 	.cons			= AMBA_CONSOLE,
690 };
691 
692 static int pl010_probe(struct amba_device *dev, const struct amba_id *id)
693 {
694 	struct uart_amba_port *uap;
695 	void __iomem *base;
696 	int i, ret;
697 
698 	for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
699 		if (amba_ports[i] == NULL)
700 			break;
701 
702 	if (i == ARRAY_SIZE(amba_ports))
703 		return -EBUSY;
704 
705 	uap = devm_kzalloc(&dev->dev, sizeof(struct uart_amba_port),
706 			   GFP_KERNEL);
707 	if (!uap)
708 		return -ENOMEM;
709 
710 	base = devm_ioremap(&dev->dev, dev->res.start,
711 			    resource_size(&dev->res));
712 	if (!base)
713 		return -ENOMEM;
714 
715 	uap->clk = devm_clk_get(&dev->dev, NULL);
716 	if (IS_ERR(uap->clk))
717 		return PTR_ERR(uap->clk);
718 
719 	uap->port.dev = &dev->dev;
720 	uap->port.mapbase = dev->res.start;
721 	uap->port.membase = base;
722 	uap->port.iotype = UPIO_MEM;
723 	uap->port.irq = dev->irq[0];
724 	uap->port.fifosize = 16;
725 	uap->port.has_sysrq = IS_ENABLED(CONFIG_SERIAL_AMBA_PL010_CONSOLE);
726 	uap->port.ops = &amba_pl010_pops;
727 	uap->port.flags = UPF_BOOT_AUTOCONF;
728 	uap->port.line = i;
729 	uap->dev = dev;
730 	uap->data = dev_get_platdata(&dev->dev);
731 
732 	amba_ports[i] = uap;
733 
734 	amba_set_drvdata(dev, uap);
735 
736 	mutex_lock(&amba_reg_lock);
737 	if (!amba_reg.state) {
738 		ret = uart_register_driver(&amba_reg);
739 		if (ret < 0) {
740 			mutex_unlock(&amba_reg_lock);
741 			dev_err(uap->port.dev,
742 				"Failed to register AMBA-PL010 driver\n");
743 			return ret;
744 		}
745 	}
746 	mutex_unlock(&amba_reg_lock);
747 
748 	ret = uart_add_one_port(&amba_reg, &uap->port);
749 	if (ret)
750 		amba_ports[i] = NULL;
751 
752 	return ret;
753 }
754 
755 static void pl010_remove(struct amba_device *dev)
756 {
757 	struct uart_amba_port *uap = amba_get_drvdata(dev);
758 	int i;
759 	bool busy = false;
760 
761 	uart_remove_one_port(&amba_reg, &uap->port);
762 
763 	for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
764 		if (amba_ports[i] == uap)
765 			amba_ports[i] = NULL;
766 		else if (amba_ports[i])
767 			busy = true;
768 
769 	if (!busy)
770 		uart_unregister_driver(&amba_reg);
771 }
772 
773 #ifdef CONFIG_PM_SLEEP
774 static int pl010_suspend(struct device *dev)
775 {
776 	struct uart_amba_port *uap = dev_get_drvdata(dev);
777 
778 	if (uap)
779 		uart_suspend_port(&amba_reg, &uap->port);
780 
781 	return 0;
782 }
783 
784 static int pl010_resume(struct device *dev)
785 {
786 	struct uart_amba_port *uap = dev_get_drvdata(dev);
787 
788 	if (uap)
789 		uart_resume_port(&amba_reg, &uap->port);
790 
791 	return 0;
792 }
793 #endif
794 
795 static SIMPLE_DEV_PM_OPS(pl010_dev_pm_ops, pl010_suspend, pl010_resume);
796 
797 static const struct amba_id pl010_ids[] = {
798 	{
799 		.id	= 0x00041010,
800 		.mask	= 0x000fffff,
801 	},
802 	{ 0, 0 },
803 };
804 
805 MODULE_DEVICE_TABLE(amba, pl010_ids);
806 
807 static struct amba_driver pl010_driver = {
808 	.drv = {
809 		.name	= "uart-pl010",
810 		.pm	= &pl010_dev_pm_ops,
811 	},
812 	.id_table	= pl010_ids,
813 	.probe		= pl010_probe,
814 	.remove		= pl010_remove,
815 };
816 
817 static int __init pl010_init(void)
818 {
819 	printk(KERN_INFO "Serial: AMBA driver\n");
820 
821 	return  amba_driver_register(&pl010_driver);
822 }
823 
824 static void __exit pl010_exit(void)
825 {
826 	amba_driver_unregister(&pl010_driver);
827 }
828 
829 module_init(pl010_init);
830 module_exit(pl010_exit);
831 
832 MODULE_AUTHOR("ARM Ltd/Deep Blue Solutions Ltd");
833 MODULE_DESCRIPTION("ARM AMBA serial port driver");
834 MODULE_LICENSE("GPL");
835