xref: /openbmc/linux/drivers/tty/serial/sunhv.c (revision 33ac9dba) 
1 /* sunhv.c: Serial driver for SUN4V hypervisor console.
2  *
3  * Copyright (C) 2006, 2007 David S. Miller (davem@davemloft.net)
4  */
5 
6 #include <linux/module.h>
7 #include <linux/kernel.h>
8 #include <linux/errno.h>
9 #include <linux/tty.h>
10 #include <linux/tty_flip.h>
11 #include <linux/major.h>
12 #include <linux/circ_buf.h>
13 #include <linux/serial.h>
14 #include <linux/sysrq.h>
15 #include <linux/console.h>
16 #include <linux/spinlock.h>
17 #include <linux/slab.h>
18 #include <linux/delay.h>
19 #include <linux/init.h>
20 #include <linux/of_device.h>
21 
22 #include <asm/hypervisor.h>
23 #include <asm/spitfire.h>
24 #include <asm/prom.h>
25 #include <asm/irq.h>
26 #include <asm/setup.h>
27 
28 #if defined(CONFIG_MAGIC_SYSRQ)
29 #define SUPPORT_SYSRQ
30 #endif
31 
32 #include <linux/serial_core.h>
33 #include <linux/sunserialcore.h>
34 
35 #define CON_BREAK	((long)-1)
36 #define CON_HUP		((long)-2)
37 
38 #define IGNORE_BREAK	0x1
39 #define IGNORE_ALL	0x2
40 
41 static char *con_write_page;
42 static char *con_read_page;
43 
44 static int hung_up = 0;
45 
46 static void transmit_chars_putchar(struct uart_port *port, struct circ_buf *xmit)
47 {
48 	while (!uart_circ_empty(xmit)) {
49 		long status = sun4v_con_putchar(xmit->buf[xmit->tail]);
50 
51 		if (status != HV_EOK)
52 			break;
53 
54 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
55 		port->icount.tx++;
56 	}
57 }
58 
59 static void transmit_chars_write(struct uart_port *port, struct circ_buf *xmit)
60 {
61 	while (!uart_circ_empty(xmit)) {
62 		unsigned long ra = __pa(xmit->buf + xmit->tail);
63 		unsigned long len, status, sent;
64 
65 		len = CIRC_CNT_TO_END(xmit->head, xmit->tail,
66 				      UART_XMIT_SIZE);
67 		status = sun4v_con_write(ra, len, &sent);
68 		if (status != HV_EOK)
69 			break;
70 		xmit->tail = (xmit->tail + sent) & (UART_XMIT_SIZE - 1);
71 		port->icount.tx += sent;
72 	}
73 }
74 
75 static int receive_chars_getchar(struct uart_port *port)
76 {
77 	int saw_console_brk = 0;
78 	int limit = 10000;
79 
80 	while (limit-- > 0) {
81 		long status;
82 		long c = sun4v_con_getchar(&status);
83 
84 		if (status == HV_EWOULDBLOCK)
85 			break;
86 
87 		if (c == CON_BREAK) {
88 			if (uart_handle_break(port))
89 				continue;
90 			saw_console_brk = 1;
91 			c = 0;
92 		}
93 
94 		if (c == CON_HUP) {
95 			hung_up = 1;
96 			uart_handle_dcd_change(port, 0);
97 		} else if (hung_up) {
98 			hung_up = 0;
99 			uart_handle_dcd_change(port, 1);
100 		}
101 
102 		if (port->state == NULL) {
103 			uart_handle_sysrq_char(port, c);
104 			continue;
105 		}
106 
107 		port->icount.rx++;
108 
109 		if (uart_handle_sysrq_char(port, c))
110 			continue;
111 
112 		tty_insert_flip_char(&port->state->port, c, TTY_NORMAL);
113 	}
114 
115 	return saw_console_brk;
116 }
117 
118 static int receive_chars_read(struct uart_port *port)
119 {
120 	int saw_console_brk = 0;
121 	int limit = 10000;
122 
123 	while (limit-- > 0) {
124 		unsigned long ra = __pa(con_read_page);
125 		unsigned long bytes_read, i;
126 		long stat = sun4v_con_read(ra, PAGE_SIZE, &bytes_read);
127 
128 		if (stat != HV_EOK) {
129 			bytes_read = 0;
130 
131 			if (stat == CON_BREAK) {
132 				if (uart_handle_break(port))
133 					continue;
134 				saw_console_brk = 1;
135 				*con_read_page = 0;
136 				bytes_read = 1;
137 			} else if (stat == CON_HUP) {
138 				hung_up = 1;
139 				uart_handle_dcd_change(port, 0);
140 				continue;
141 			} else {
142 				/* HV_EWOULDBLOCK, etc.  */
143 				break;
144 			}
145 		}
146 
147 		if (hung_up) {
148 			hung_up = 0;
149 			uart_handle_dcd_change(port, 1);
150 		}
151 
152 		for (i = 0; i < bytes_read; i++)
153 			uart_handle_sysrq_char(port, con_read_page[i]);
154 
155 		if (port->state == NULL)
156 			continue;
157 
158 		port->icount.rx += bytes_read;
159 
160 		tty_insert_flip_string(&port->state->port, con_read_page,
161 				bytes_read);
162 	}
163 
164 	return saw_console_brk;
165 }
166 
167 struct sunhv_ops {
168 	void (*transmit_chars)(struct uart_port *port, struct circ_buf *xmit);
169 	int (*receive_chars)(struct uart_port *port);
170 };
171 
172 static struct sunhv_ops bychar_ops = {
173 	.transmit_chars = transmit_chars_putchar,
174 	.receive_chars = receive_chars_getchar,
175 };
176 
177 static struct sunhv_ops bywrite_ops = {
178 	.transmit_chars = transmit_chars_write,
179 	.receive_chars = receive_chars_read,
180 };
181 
182 static struct sunhv_ops *sunhv_ops = &bychar_ops;
183 
184 static struct tty_port *receive_chars(struct uart_port *port)
185 {
186 	struct tty_port *tport = NULL;
187 
188 	if (port->state != NULL)		/* Unopened serial console */
189 		tport = &port->state->port;
190 
191 	if (sunhv_ops->receive_chars(port))
192 		sun_do_break();
193 
194 	return tport;
195 }
196 
197 static void transmit_chars(struct uart_port *port)
198 {
199 	struct circ_buf *xmit;
200 
201 	if (!port->state)
202 		return;
203 
204 	xmit = &port->state->xmit;
205 	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
206 		return;
207 
208 	sunhv_ops->transmit_chars(port, xmit);
209 
210 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
211 		uart_write_wakeup(port);
212 }
213 
214 static irqreturn_t sunhv_interrupt(int irq, void *dev_id)
215 {
216 	struct uart_port *port = dev_id;
217 	struct tty_port *tport;
218 	unsigned long flags;
219 
220 	spin_lock_irqsave(&port->lock, flags);
221 	tport = receive_chars(port);
222 	transmit_chars(port);
223 	spin_unlock_irqrestore(&port->lock, flags);
224 
225 	if (tport)
226 		tty_flip_buffer_push(tport);
227 
228 	return IRQ_HANDLED;
229 }
230 
231 /* port->lock is not held.  */
232 static unsigned int sunhv_tx_empty(struct uart_port *port)
233 {
234 	/* Transmitter is always empty for us.  If the circ buffer
235 	 * is non-empty or there is an x_char pending, our caller
236 	 * will do the right thing and ignore what we return here.
237 	 */
238 	return TIOCSER_TEMT;
239 }
240 
241 /* port->lock held by caller.  */
242 static void sunhv_set_mctrl(struct uart_port *port, unsigned int mctrl)
243 {
244 	return;
245 }
246 
247 /* port->lock is held by caller and interrupts are disabled.  */
248 static unsigned int sunhv_get_mctrl(struct uart_port *port)
249 {
250 	return TIOCM_DSR | TIOCM_CAR | TIOCM_CTS;
251 }
252 
253 /* port->lock held by caller.  */
254 static void sunhv_stop_tx(struct uart_port *port)
255 {
256 	return;
257 }
258 
259 /* port->lock held by caller.  */
260 static void sunhv_start_tx(struct uart_port *port)
261 {
262 	transmit_chars(port);
263 }
264 
265 /* port->lock is not held.  */
266 static void sunhv_send_xchar(struct uart_port *port, char ch)
267 {
268 	unsigned long flags;
269 	int limit = 10000;
270 
271 	spin_lock_irqsave(&port->lock, flags);
272 
273 	while (limit-- > 0) {
274 		long status = sun4v_con_putchar(ch);
275 		if (status == HV_EOK)
276 			break;
277 		udelay(1);
278 	}
279 
280 	spin_unlock_irqrestore(&port->lock, flags);
281 }
282 
283 /* port->lock held by caller.  */
284 static void sunhv_stop_rx(struct uart_port *port)
285 {
286 }
287 
288 /* port->lock is not held.  */
289 static void sunhv_break_ctl(struct uart_port *port, int break_state)
290 {
291 	if (break_state) {
292 		unsigned long flags;
293 		int limit = 10000;
294 
295 		spin_lock_irqsave(&port->lock, flags);
296 
297 		while (limit-- > 0) {
298 			long status = sun4v_con_putchar(CON_BREAK);
299 			if (status == HV_EOK)
300 				break;
301 			udelay(1);
302 		}
303 
304 		spin_unlock_irqrestore(&port->lock, flags);
305 	}
306 }
307 
308 /* port->lock is not held.  */
309 static int sunhv_startup(struct uart_port *port)
310 {
311 	return 0;
312 }
313 
314 /* port->lock is not held.  */
315 static void sunhv_shutdown(struct uart_port *port)
316 {
317 }
318 
319 /* port->lock is not held.  */
320 static void sunhv_set_termios(struct uart_port *port, struct ktermios *termios,
321 			      struct ktermios *old)
322 {
323 	unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
324 	unsigned int quot = uart_get_divisor(port, baud);
325 	unsigned int iflag, cflag;
326 	unsigned long flags;
327 
328 	spin_lock_irqsave(&port->lock, flags);
329 
330 	iflag = termios->c_iflag;
331 	cflag = termios->c_cflag;
332 
333 	port->ignore_status_mask = 0;
334 	if (iflag & IGNBRK)
335 		port->ignore_status_mask |= IGNORE_BREAK;
336 	if ((cflag & CREAD) == 0)
337 		port->ignore_status_mask |= IGNORE_ALL;
338 
339 	/* XXX */
340 	uart_update_timeout(port, cflag,
341 			    (port->uartclk / (16 * quot)));
342 
343 	spin_unlock_irqrestore(&port->lock, flags);
344 }
345 
346 static const char *sunhv_type(struct uart_port *port)
347 {
348 	return "SUN4V HCONS";
349 }
350 
351 static void sunhv_release_port(struct uart_port *port)
352 {
353 }
354 
355 static int sunhv_request_port(struct uart_port *port)
356 {
357 	return 0;
358 }
359 
360 static void sunhv_config_port(struct uart_port *port, int flags)
361 {
362 }
363 
364 static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
365 {
366 	return -EINVAL;
367 }
368 
369 static struct uart_ops sunhv_pops = {
370 	.tx_empty	= sunhv_tx_empty,
371 	.set_mctrl	= sunhv_set_mctrl,
372 	.get_mctrl	= sunhv_get_mctrl,
373 	.stop_tx	= sunhv_stop_tx,
374 	.start_tx	= sunhv_start_tx,
375 	.send_xchar	= sunhv_send_xchar,
376 	.stop_rx	= sunhv_stop_rx,
377 	.break_ctl	= sunhv_break_ctl,
378 	.startup	= sunhv_startup,
379 	.shutdown	= sunhv_shutdown,
380 	.set_termios	= sunhv_set_termios,
381 	.type		= sunhv_type,
382 	.release_port	= sunhv_release_port,
383 	.request_port	= sunhv_request_port,
384 	.config_port	= sunhv_config_port,
385 	.verify_port	= sunhv_verify_port,
386 };
387 
388 static struct uart_driver sunhv_reg = {
389 	.owner			= THIS_MODULE,
390 	.driver_name		= "sunhv",
391 	.dev_name		= "ttyS",
392 	.major			= TTY_MAJOR,
393 };
394 
395 static struct uart_port *sunhv_port;
396 
397 /* Copy 's' into the con_write_page, decoding "\n" into
398  * "\r\n" along the way.  We have to return two lengths
399  * because the caller needs to know how much to advance
400  * 's' and also how many bytes to output via con_write_page.
401  */
402 static int fill_con_write_page(const char *s, unsigned int n,
403 			       unsigned long *page_bytes)
404 {
405 	const char *orig_s = s;
406 	char *p = con_write_page;
407 	int left = PAGE_SIZE;
408 
409 	while (n--) {
410 		if (*s == '\n') {
411 			if (left < 2)
412 				break;
413 			*p++ = '\r';
414 			left--;
415 		} else if (left < 1)
416 			break;
417 		*p++ = *s++;
418 		left--;
419 	}
420 	*page_bytes = p - con_write_page;
421 	return s - orig_s;
422 }
423 
424 static void sunhv_console_write_paged(struct console *con, const char *s, unsigned n)
425 {
426 	struct uart_port *port = sunhv_port;
427 	unsigned long flags;
428 	int locked = 1;
429 
430 	if (port->sysrq || oops_in_progress)
431 		locked = spin_trylock_irqsave(&port->lock, flags);
432 	else
433 		spin_lock_irqsave(&port->lock, flags);
434 
435 	while (n > 0) {
436 		unsigned long ra = __pa(con_write_page);
437 		unsigned long page_bytes;
438 		unsigned int cpy = fill_con_write_page(s, n,
439 						       &page_bytes);
440 
441 		n -= cpy;
442 		s += cpy;
443 		while (page_bytes > 0) {
444 			unsigned long written;
445 			int limit = 1000000;
446 
447 			while (limit--) {
448 				unsigned long stat;
449 
450 				stat = sun4v_con_write(ra, page_bytes,
451 						       &written);
452 				if (stat == HV_EOK)
453 					break;
454 				udelay(1);
455 			}
456 			if (limit < 0)
457 				break;
458 			page_bytes -= written;
459 			ra += written;
460 		}
461 	}
462 
463 	if (locked)
464 		spin_unlock_irqrestore(&port->lock, flags);
465 }
466 
467 static inline void sunhv_console_putchar(struct uart_port *port, char c)
468 {
469 	int limit = 1000000;
470 
471 	while (limit-- > 0) {
472 		long status = sun4v_con_putchar(c);
473 		if (status == HV_EOK)
474 			break;
475 		udelay(1);
476 	}
477 }
478 
479 static void sunhv_console_write_bychar(struct console *con, const char *s, unsigned n)
480 {
481 	struct uart_port *port = sunhv_port;
482 	unsigned long flags;
483 	int i, locked = 1;
484 
485 	if (port->sysrq || oops_in_progress)
486 		locked = spin_trylock_irqsave(&port->lock, flags);
487 	else
488 		spin_lock_irqsave(&port->lock, flags);
489 	if (port->sysrq) {
490 		locked = 0;
491 	} else if (oops_in_progress) {
492 		locked = spin_trylock(&port->lock);
493 	} else
494 		spin_lock(&port->lock);
495 
496 	for (i = 0; i < n; i++) {
497 		if (*s == '\n')
498 			sunhv_console_putchar(port, '\r');
499 		sunhv_console_putchar(port, *s++);
500 	}
501 
502 	if (locked)
503 		spin_unlock_irqrestore(&port->lock, flags);
504 }
505 
506 static struct console sunhv_console = {
507 	.name	=	"ttyHV",
508 	.write	=	sunhv_console_write_bychar,
509 	.device	=	uart_console_device,
510 	.flags	=	CON_PRINTBUFFER,
511 	.index	=	-1,
512 	.data	=	&sunhv_reg,
513 };
514 
515 static int hv_probe(struct platform_device *op)
516 {
517 	struct uart_port *port;
518 	unsigned long minor;
519 	int err;
520 
521 	if (op->archdata.irqs[0] == 0xffffffff)
522 		return -ENODEV;
523 
524 	port = kzalloc(sizeof(struct uart_port), GFP_KERNEL);
525 	if (unlikely(!port))
526 		return -ENOMEM;
527 
528 	minor = 1;
529 	if (sun4v_hvapi_register(HV_GRP_CORE, 1, &minor) == 0 &&
530 	    minor >= 1) {
531 		err = -ENOMEM;
532 		con_write_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
533 		if (!con_write_page)
534 			goto out_free_port;
535 
536 		con_read_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
537 		if (!con_read_page)
538 			goto out_free_con_write_page;
539 
540 		sunhv_console.write = sunhv_console_write_paged;
541 		sunhv_ops = &bywrite_ops;
542 	}
543 
544 	sunhv_port = port;
545 
546 	port->line = 0;
547 	port->ops = &sunhv_pops;
548 	port->type = PORT_SUNHV;
549 	port->uartclk = ( 29491200 / 16 ); /* arbitrary */
550 
551 	port->membase = (unsigned char __iomem *) __pa(port);
552 
553 	port->irq = op->archdata.irqs[0];
554 
555 	port->dev = &op->dev;
556 
557 	err = sunserial_register_minors(&sunhv_reg, 1);
558 	if (err)
559 		goto out_free_con_read_page;
560 
561 	sunserial_console_match(&sunhv_console, op->dev.of_node,
562 				&sunhv_reg, port->line, false);
563 
564 	err = uart_add_one_port(&sunhv_reg, port);
565 	if (err)
566 		goto out_unregister_driver;
567 
568 	err = request_irq(port->irq, sunhv_interrupt, 0, "hvcons", port);
569 	if (err)
570 		goto out_remove_port;
571 
572 	platform_set_drvdata(op, port);
573 
574 	return 0;
575 
576 out_remove_port:
577 	uart_remove_one_port(&sunhv_reg, port);
578 
579 out_unregister_driver:
580 	sunserial_unregister_minors(&sunhv_reg, 1);
581 
582 out_free_con_read_page:
583 	kfree(con_read_page);
584 
585 out_free_con_write_page:
586 	kfree(con_write_page);
587 
588 out_free_port:
589 	kfree(port);
590 	sunhv_port = NULL;
591 	return err;
592 }
593 
594 static int hv_remove(struct platform_device *dev)
595 {
596 	struct uart_port *port = platform_get_drvdata(dev);
597 
598 	free_irq(port->irq, port);
599 
600 	uart_remove_one_port(&sunhv_reg, port);
601 
602 	sunserial_unregister_minors(&sunhv_reg, 1);
603 
604 	kfree(port);
605 	sunhv_port = NULL;
606 
607 	return 0;
608 }
609 
610 static const struct of_device_id hv_match[] = {
611 	{
612 		.name = "console",
613 		.compatible = "qcn",
614 	},
615 	{
616 		.name = "console",
617 		.compatible = "SUNW,sun4v-console",
618 	},
619 	{},
620 };
621 MODULE_DEVICE_TABLE(of, hv_match);
622 
623 static struct platform_driver hv_driver = {
624 	.driver = {
625 		.name = "hv",
626 		.owner = THIS_MODULE,
627 		.of_match_table = hv_match,
628 	},
629 	.probe		= hv_probe,
630 	.remove		= hv_remove,
631 };
632 
633 static int __init sunhv_init(void)
634 {
635 	if (tlb_type != hypervisor)
636 		return -ENODEV;
637 
638 	return platform_driver_register(&hv_driver);
639 }
640 
641 static void __exit sunhv_exit(void)
642 {
643 	platform_driver_unregister(&hv_driver);
644 }
645 
646 module_init(sunhv_init);
647 module_exit(sunhv_exit);
648 
649 MODULE_AUTHOR("David S. Miller");
650 MODULE_DESCRIPTION("SUN4V Hypervisor console driver");
651 MODULE_VERSION("2.0");
652 MODULE_LICENSE("GPL");
653