xref: /linux/drivers/tty/serial/sunhv.c (revision ca55b2fef3a9373fcfc30f82fd26bc7fccbda732) 
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/kernel.h>
7 #include <linux/errno.h>
8 #include <linux/tty.h>
9 #include <linux/tty_flip.h>
10 #include <linux/major.h>
11 #include <linux/circ_buf.h>
12 #include <linux/serial.h>
13 #include <linux/sysrq.h>
14 #include <linux/console.h>
15 #include <linux/spinlock.h>
16 #include <linux/slab.h>
17 #include <linux/delay.h>
18 #include <linux/init.h>
19 #include <linux/of_device.h>
20 
21 #include <asm/hypervisor.h>
22 #include <asm/spitfire.h>
23 #include <asm/prom.h>
24 #include <asm/irq.h>
25 #include <asm/setup.h>
26 
27 #if defined(CONFIG_MAGIC_SYSRQ)
28 #define SUPPORT_SYSRQ
29 #endif
30 
31 #include <linux/serial_core.h>
32 #include <linux/sunserialcore.h>
33 
34 #define CON_BREAK	((long)-1)
35 #define CON_HUP		((long)-2)
36 
37 #define IGNORE_BREAK	0x1
38 #define IGNORE_ALL	0x2
39 
40 static char *con_write_page;
41 static char *con_read_page;
42 
43 static int hung_up = 0;
44 
45 static void transmit_chars_putchar(struct uart_port *port, struct circ_buf *xmit)
46 {
47 	while (!uart_circ_empty(xmit)) {
48 		long status = sun4v_con_putchar(xmit->buf[xmit->tail]);
49 
50 		if (status != HV_EOK)
51 			break;
52 
53 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
54 		port->icount.tx++;
55 	}
56 }
57 
58 static void transmit_chars_write(struct uart_port *port, struct circ_buf *xmit)
59 {
60 	while (!uart_circ_empty(xmit)) {
61 		unsigned long ra = __pa(xmit->buf + xmit->tail);
62 		unsigned long len, status, sent;
63 
64 		len = CIRC_CNT_TO_END(xmit->head, xmit->tail,
65 				      UART_XMIT_SIZE);
66 		status = sun4v_con_write(ra, len, &sent);
67 		if (status != HV_EOK)
68 			break;
69 		xmit->tail = (xmit->tail + sent) & (UART_XMIT_SIZE - 1);
70 		port->icount.tx += sent;
71 	}
72 }
73 
74 static int receive_chars_getchar(struct uart_port *port)
75 {
76 	int saw_console_brk = 0;
77 	int limit = 10000;
78 
79 	while (limit-- > 0) {
80 		long status;
81 		long c = sun4v_con_getchar(&status);
82 
83 		if (status == HV_EWOULDBLOCK)
84 			break;
85 
86 		if (c == CON_BREAK) {
87 			if (uart_handle_break(port))
88 				continue;
89 			saw_console_brk = 1;
90 			c = 0;
91 		}
92 
93 		if (c == CON_HUP) {
94 			hung_up = 1;
95 			uart_handle_dcd_change(port, 0);
96 		} else if (hung_up) {
97 			hung_up = 0;
98 			uart_handle_dcd_change(port, 1);
99 		}
100 
101 		if (port->state == NULL) {
102 			uart_handle_sysrq_char(port, c);
103 			continue;
104 		}
105 
106 		port->icount.rx++;
107 
108 		if (uart_handle_sysrq_char(port, c))
109 			continue;
110 
111 		tty_insert_flip_char(&port->state->port, c, TTY_NORMAL);
112 	}
113 
114 	return saw_console_brk;
115 }
116 
117 static int receive_chars_read(struct uart_port *port)
118 {
119 	int saw_console_brk = 0;
120 	int limit = 10000;
121 
122 	while (limit-- > 0) {
123 		unsigned long ra = __pa(con_read_page);
124 		unsigned long bytes_read, i;
125 		long stat = sun4v_con_read(ra, PAGE_SIZE, &bytes_read);
126 
127 		if (stat != HV_EOK) {
128 			bytes_read = 0;
129 
130 			if (stat == CON_BREAK) {
131 				if (uart_handle_break(port))
132 					continue;
133 				saw_console_brk = 1;
134 				*con_read_page = 0;
135 				bytes_read = 1;
136 			} else if (stat == CON_HUP) {
137 				hung_up = 1;
138 				uart_handle_dcd_change(port, 0);
139 				continue;
140 			} else {
141 				/* HV_EWOULDBLOCK, etc.  */
142 				break;
143 			}
144 		}
145 
146 		if (hung_up) {
147 			hung_up = 0;
148 			uart_handle_dcd_change(port, 1);
149 		}
150 
151 		for (i = 0; i < bytes_read; i++)
152 			uart_handle_sysrq_char(port, con_read_page[i]);
153 
154 		if (port->state == NULL)
155 			continue;
156 
157 		port->icount.rx += bytes_read;
158 
159 		tty_insert_flip_string(&port->state->port, con_read_page,
160 				bytes_read);
161 	}
162 
163 	return saw_console_brk;
164 }
165 
166 struct sunhv_ops {
167 	void (*transmit_chars)(struct uart_port *port, struct circ_buf *xmit);
168 	int (*receive_chars)(struct uart_port *port);
169 };
170 
171 static struct sunhv_ops bychar_ops = {
172 	.transmit_chars = transmit_chars_putchar,
173 	.receive_chars = receive_chars_getchar,
174 };
175 
176 static struct sunhv_ops bywrite_ops = {
177 	.transmit_chars = transmit_chars_write,
178 	.receive_chars = receive_chars_read,
179 };
180 
181 static struct sunhv_ops *sunhv_ops = &bychar_ops;
182 
183 static struct tty_port *receive_chars(struct uart_port *port)
184 {
185 	struct tty_port *tport = NULL;
186 
187 	if (port->state != NULL)		/* Unopened serial console */
188 		tport = &port->state->port;
189 
190 	if (sunhv_ops->receive_chars(port))
191 		sun_do_break();
192 
193 	return tport;
194 }
195 
196 static void transmit_chars(struct uart_port *port)
197 {
198 	struct circ_buf *xmit;
199 
200 	if (!port->state)
201 		return;
202 
203 	xmit = &port->state->xmit;
204 	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
205 		return;
206 
207 	sunhv_ops->transmit_chars(port, xmit);
208 
209 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
210 		uart_write_wakeup(port);
211 }
212 
213 static irqreturn_t sunhv_interrupt(int irq, void *dev_id)
214 {
215 	struct uart_port *port = dev_id;
216 	struct tty_port *tport;
217 	unsigned long flags;
218 
219 	spin_lock_irqsave(&port->lock, flags);
220 	tport = receive_chars(port);
221 	transmit_chars(port);
222 	spin_unlock_irqrestore(&port->lock, flags);
223 
224 	if (tport)
225 		tty_flip_buffer_push(tport);
226 
227 	return IRQ_HANDLED;
228 }
229 
230 /* port->lock is not held.  */
231 static unsigned int sunhv_tx_empty(struct uart_port *port)
232 {
233 	/* Transmitter is always empty for us.  If the circ buffer
234 	 * is non-empty or there is an x_char pending, our caller
235 	 * will do the right thing and ignore what we return here.
236 	 */
237 	return TIOCSER_TEMT;
238 }
239 
240 /* port->lock held by caller.  */
241 static void sunhv_set_mctrl(struct uart_port *port, unsigned int mctrl)
242 {
243 	return;
244 }
245 
246 /* port->lock is held by caller and interrupts are disabled.  */
247 static unsigned int sunhv_get_mctrl(struct uart_port *port)
248 {
249 	return TIOCM_DSR | TIOCM_CAR | TIOCM_CTS;
250 }
251 
252 /* port->lock held by caller.  */
253 static void sunhv_stop_tx(struct uart_port *port)
254 {
255 	return;
256 }
257 
258 /* port->lock held by caller.  */
259 static void sunhv_start_tx(struct uart_port *port)
260 {
261 	transmit_chars(port);
262 }
263 
264 /* port->lock is not held.  */
265 static void sunhv_send_xchar(struct uart_port *port, char ch)
266 {
267 	unsigned long flags;
268 	int limit = 10000;
269 
270 	if (ch == __DISABLED_CHAR)
271 		return;
272 
273 	spin_lock_irqsave(&port->lock, flags);
274 
275 	while (limit-- > 0) {
276 		long status = sun4v_con_putchar(ch);
277 		if (status == HV_EOK)
278 			break;
279 		udelay(1);
280 	}
281 
282 	spin_unlock_irqrestore(&port->lock, flags);
283 }
284 
285 /* port->lock held by caller.  */
286 static void sunhv_stop_rx(struct uart_port *port)
287 {
288 }
289 
290 /* port->lock is not held.  */
291 static void sunhv_break_ctl(struct uart_port *port, int break_state)
292 {
293 	if (break_state) {
294 		unsigned long flags;
295 		int limit = 10000;
296 
297 		spin_lock_irqsave(&port->lock, flags);
298 
299 		while (limit-- > 0) {
300 			long status = sun4v_con_putchar(CON_BREAK);
301 			if (status == HV_EOK)
302 				break;
303 			udelay(1);
304 		}
305 
306 		spin_unlock_irqrestore(&port->lock, flags);
307 	}
308 }
309 
310 /* port->lock is not held.  */
311 static int sunhv_startup(struct uart_port *port)
312 {
313 	return 0;
314 }
315 
316 /* port->lock is not held.  */
317 static void sunhv_shutdown(struct uart_port *port)
318 {
319 }
320 
321 /* port->lock is not held.  */
322 static void sunhv_set_termios(struct uart_port *port, struct ktermios *termios,
323 			      struct ktermios *old)
324 {
325 	unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
326 	unsigned int quot = uart_get_divisor(port, baud);
327 	unsigned int iflag, cflag;
328 	unsigned long flags;
329 
330 	spin_lock_irqsave(&port->lock, flags);
331 
332 	iflag = termios->c_iflag;
333 	cflag = termios->c_cflag;
334 
335 	port->ignore_status_mask = 0;
336 	if (iflag & IGNBRK)
337 		port->ignore_status_mask |= IGNORE_BREAK;
338 	if ((cflag & CREAD) == 0)
339 		port->ignore_status_mask |= IGNORE_ALL;
340 
341 	/* XXX */
342 	uart_update_timeout(port, cflag,
343 			    (port->uartclk / (16 * quot)));
344 
345 	spin_unlock_irqrestore(&port->lock, flags);
346 }
347 
348 static const char *sunhv_type(struct uart_port *port)
349 {
350 	return "SUN4V HCONS";
351 }
352 
353 static void sunhv_release_port(struct uart_port *port)
354 {
355 }
356 
357 static int sunhv_request_port(struct uart_port *port)
358 {
359 	return 0;
360 }
361 
362 static void sunhv_config_port(struct uart_port *port, int flags)
363 {
364 }
365 
366 static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
367 {
368 	return -EINVAL;
369 }
370 
371 static struct uart_ops sunhv_pops = {
372 	.tx_empty	= sunhv_tx_empty,
373 	.set_mctrl	= sunhv_set_mctrl,
374 	.get_mctrl	= sunhv_get_mctrl,
375 	.stop_tx	= sunhv_stop_tx,
376 	.start_tx	= sunhv_start_tx,
377 	.send_xchar	= sunhv_send_xchar,
378 	.stop_rx	= sunhv_stop_rx,
379 	.break_ctl	= sunhv_break_ctl,
380 	.startup	= sunhv_startup,
381 	.shutdown	= sunhv_shutdown,
382 	.set_termios	= sunhv_set_termios,
383 	.type		= sunhv_type,
384 	.release_port	= sunhv_release_port,
385 	.request_port	= sunhv_request_port,
386 	.config_port	= sunhv_config_port,
387 	.verify_port	= sunhv_verify_port,
388 };
389 
390 static struct uart_driver sunhv_reg = {
391 	.owner			= THIS_MODULE,
392 	.driver_name		= "sunhv",
393 	.dev_name		= "ttyS",
394 	.major			= TTY_MAJOR,
395 };
396 
397 static struct uart_port *sunhv_port;
398 
399 /* Copy 's' into the con_write_page, decoding "\n" into
400  * "\r\n" along the way.  We have to return two lengths
401  * because the caller needs to know how much to advance
402  * 's' and also how many bytes to output via con_write_page.
403  */
404 static int fill_con_write_page(const char *s, unsigned int n,
405 			       unsigned long *page_bytes)
406 {
407 	const char *orig_s = s;
408 	char *p = con_write_page;
409 	int left = PAGE_SIZE;
410 
411 	while (n--) {
412 		if (*s == '\n') {
413 			if (left < 2)
414 				break;
415 			*p++ = '\r';
416 			left--;
417 		} else if (left < 1)
418 			break;
419 		*p++ = *s++;
420 		left--;
421 	}
422 	*page_bytes = p - con_write_page;
423 	return s - orig_s;
424 }
425 
426 static void sunhv_console_write_paged(struct console *con, const char *s, unsigned n)
427 {
428 	struct uart_port *port = sunhv_port;
429 	unsigned long flags;
430 	int locked = 1;
431 
432 	if (port->sysrq || oops_in_progress)
433 		locked = spin_trylock_irqsave(&port->lock, flags);
434 	else
435 		spin_lock_irqsave(&port->lock, flags);
436 
437 	while (n > 0) {
438 		unsigned long ra = __pa(con_write_page);
439 		unsigned long page_bytes;
440 		unsigned int cpy = fill_con_write_page(s, n,
441 						       &page_bytes);
442 
443 		n -= cpy;
444 		s += cpy;
445 		while (page_bytes > 0) {
446 			unsigned long written;
447 			int limit = 1000000;
448 
449 			while (limit--) {
450 				unsigned long stat;
451 
452 				stat = sun4v_con_write(ra, page_bytes,
453 						       &written);
454 				if (stat == HV_EOK)
455 					break;
456 				udelay(1);
457 			}
458 			if (limit < 0)
459 				break;
460 			page_bytes -= written;
461 			ra += written;
462 		}
463 	}
464 
465 	if (locked)
466 		spin_unlock_irqrestore(&port->lock, flags);
467 }
468 
469 static inline void sunhv_console_putchar(struct uart_port *port, char c)
470 {
471 	int limit = 1000000;
472 
473 	while (limit-- > 0) {
474 		long status = sun4v_con_putchar(c);
475 		if (status == HV_EOK)
476 			break;
477 		udelay(1);
478 	}
479 }
480 
481 static void sunhv_console_write_bychar(struct console *con, const char *s, unsigned n)
482 {
483 	struct uart_port *port = sunhv_port;
484 	unsigned long flags;
485 	int i, locked = 1;
486 
487 	if (port->sysrq || oops_in_progress)
488 		locked = spin_trylock_irqsave(&port->lock, flags);
489 	else
490 		spin_lock_irqsave(&port->lock, flags);
491 	if (port->sysrq) {
492 		locked = 0;
493 	} else if (oops_in_progress) {
494 		locked = spin_trylock(&port->lock);
495 	} else
496 		spin_lock(&port->lock);
497 
498 	for (i = 0; i < n; i++) {
499 		if (*s == '\n')
500 			sunhv_console_putchar(port, '\r');
501 		sunhv_console_putchar(port, *s++);
502 	}
503 
504 	if (locked)
505 		spin_unlock_irqrestore(&port->lock, flags);
506 }
507 
508 static struct console sunhv_console = {
509 	.name	=	"ttyHV",
510 	.write	=	sunhv_console_write_bychar,
511 	.device	=	uart_console_device,
512 	.flags	=	CON_PRINTBUFFER,
513 	.index	=	-1,
514 	.data	=	&sunhv_reg,
515 };
516 
517 static int hv_probe(struct platform_device *op)
518 {
519 	struct uart_port *port;
520 	unsigned long minor;
521 	int err;
522 
523 	if (op->archdata.irqs[0] == 0xffffffff)
524 		return -ENODEV;
525 
526 	port = kzalloc(sizeof(struct uart_port), GFP_KERNEL);
527 	if (unlikely(!port))
528 		return -ENOMEM;
529 
530 	minor = 1;
531 	if (sun4v_hvapi_register(HV_GRP_CORE, 1, &minor) == 0 &&
532 	    minor >= 1) {
533 		err = -ENOMEM;
534 		con_write_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
535 		if (!con_write_page)
536 			goto out_free_port;
537 
538 		con_read_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
539 		if (!con_read_page)
540 			goto out_free_con_write_page;
541 
542 		sunhv_console.write = sunhv_console_write_paged;
543 		sunhv_ops = &bywrite_ops;
544 	}
545 
546 	sunhv_port = port;
547 
548 	port->line = 0;
549 	port->ops = &sunhv_pops;
550 	port->type = PORT_SUNHV;
551 	port->uartclk = ( 29491200 / 16 ); /* arbitrary */
552 
553 	port->membase = (unsigned char __iomem *) __pa(port);
554 
555 	port->irq = op->archdata.irqs[0];
556 
557 	port->dev = &op->dev;
558 
559 	err = sunserial_register_minors(&sunhv_reg, 1);
560 	if (err)
561 		goto out_free_con_read_page;
562 
563 	sunserial_console_match(&sunhv_console, op->dev.of_node,
564 				&sunhv_reg, port->line, false);
565 
566 	err = uart_add_one_port(&sunhv_reg, port);
567 	if (err)
568 		goto out_unregister_driver;
569 
570 	err = request_irq(port->irq, sunhv_interrupt, 0, "hvcons", port);
571 	if (err)
572 		goto out_remove_port;
573 
574 	platform_set_drvdata(op, port);
575 
576 	return 0;
577 
578 out_remove_port:
579 	uart_remove_one_port(&sunhv_reg, port);
580 
581 out_unregister_driver:
582 	sunserial_unregister_minors(&sunhv_reg, 1);
583 
584 out_free_con_read_page:
585 	kfree(con_read_page);
586 
587 out_free_con_write_page:
588 	kfree(con_write_page);
589 
590 out_free_port:
591 	kfree(port);
592 	sunhv_port = NULL;
593 	return err;
594 }
595 
596 static int hv_remove(struct platform_device *dev)
597 {
598 	struct uart_port *port = platform_get_drvdata(dev);
599 
600 	free_irq(port->irq, port);
601 
602 	uart_remove_one_port(&sunhv_reg, port);
603 
604 	sunserial_unregister_minors(&sunhv_reg, 1);
605 
606 	kfree(port);
607 	sunhv_port = NULL;
608 
609 	return 0;
610 }
611 
612 static const struct of_device_id hv_match[] = {
613 	{
614 		.name = "console",
615 		.compatible = "qcn",
616 	},
617 	{
618 		.name = "console",
619 		.compatible = "SUNW,sun4v-console",
620 	},
621 	{},
622 };
623 
624 static struct platform_driver hv_driver = {
625 	.driver = {
626 		.name = "hv",
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 device_initcall(sunhv_init);
641 
642 #if 0 /* ...def MODULE ; never supported as such */
643 MODULE_AUTHOR("David S. Miller");
644 MODULE_DESCRIPTION("SUN4V Hypervisor console driver");
645 MODULE_VERSION("2.0");
646 MODULE_LICENSE("GPL");
647 #endif
648