xref: /linux/drivers/tty/serial/sunhv.c (revision cea0f76a483d1270ac6f6513964e3e75193dda48) 
1 // SPDX-License-Identifier: GPL-2.0
2 /* sunhv.c: Serial driver for SUN4V hypervisor console.
3  *
4  * Copyright (C) 2006, 2007 David S. Miller (davem@davemloft.net)
5  */
6 
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 #include <linux/serial_core.h>
29 #include <linux/sunserialcore.h>
30 
31 #define CON_BREAK	((long)-1)
32 #define CON_HUP		((long)-2)
33 
34 #define IGNORE_BREAK	0x1
35 #define IGNORE_ALL	0x2
36 
37 static char *con_write_page;
38 static char *con_read_page;
39 
40 static int hung_up = 0;
41 
42 static void transmit_chars_putchar(struct uart_port *port, struct circ_buf *xmit)
43 {
44 	while (!uart_circ_empty(xmit)) {
45 		long status = sun4v_con_putchar(xmit->buf[xmit->tail]);
46 
47 		if (status != HV_EOK)
48 			break;
49 
50 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
51 		port->icount.tx++;
52 	}
53 }
54 
55 static void transmit_chars_write(struct uart_port *port, struct circ_buf *xmit)
56 {
57 	while (!uart_circ_empty(xmit)) {
58 		unsigned long ra = __pa(xmit->buf + xmit->tail);
59 		unsigned long len, status, sent;
60 
61 		len = CIRC_CNT_TO_END(xmit->head, xmit->tail,
62 				      UART_XMIT_SIZE);
63 		status = sun4v_con_write(ra, len, &sent);
64 		if (status != HV_EOK)
65 			break;
66 		xmit->tail = (xmit->tail + sent) & (UART_XMIT_SIZE - 1);
67 		port->icount.tx += sent;
68 	}
69 }
70 
71 static int receive_chars_getchar(struct uart_port *port)
72 {
73 	int saw_console_brk = 0;
74 	int limit = 10000;
75 
76 	while (limit-- > 0) {
77 		long status;
78 		long c = sun4v_con_getchar(&status);
79 
80 		if (status == HV_EWOULDBLOCK)
81 			break;
82 
83 		if (c == CON_BREAK) {
84 			if (uart_handle_break(port))
85 				continue;
86 			saw_console_brk = 1;
87 			c = 0;
88 		}
89 
90 		if (c == CON_HUP) {
91 			hung_up = 1;
92 			uart_handle_dcd_change(port, 0);
93 		} else if (hung_up) {
94 			hung_up = 0;
95 			uart_handle_dcd_change(port, 1);
96 		}
97 
98 		if (port->state == NULL) {
99 			uart_handle_sysrq_char(port, c);
100 			continue;
101 		}
102 
103 		port->icount.rx++;
104 
105 		if (uart_handle_sysrq_char(port, c))
106 			continue;
107 
108 		tty_insert_flip_char(&port->state->port, c, TTY_NORMAL);
109 	}
110 
111 	return saw_console_brk;
112 }
113 
114 static int receive_chars_read(struct uart_port *port)
115 {
116 	static int saw_console_brk;
117 	int limit = 10000;
118 
119 	while (limit-- > 0) {
120 		unsigned long ra = __pa(con_read_page);
121 		unsigned long bytes_read, i;
122 		long stat = sun4v_con_read(ra, PAGE_SIZE, &bytes_read);
123 
124 		if (stat != HV_EOK) {
125 			bytes_read = 0;
126 
127 			if (stat == CON_BREAK) {
128 				if (saw_console_brk)
129 					sun_do_break();
130 
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 		if (port->sysrq != 0 &&  *con_read_page) {
152 			for (i = 0; i < bytes_read; i++)
153 				uart_handle_sysrq_char(port, con_read_page[i]);
154 			saw_console_brk = 0;
155 		}
156 
157 		if (port->state == NULL)
158 			continue;
159 
160 		port->icount.rx += bytes_read;
161 
162 		tty_insert_flip_string(&port->state->port, con_read_page,
163 				bytes_read);
164 	}
165 
166 	return saw_console_brk;
167 }
168 
169 struct sunhv_ops {
170 	void (*transmit_chars)(struct uart_port *port, struct circ_buf *xmit);
171 	int (*receive_chars)(struct uart_port *port);
172 };
173 
174 static const struct sunhv_ops bychar_ops = {
175 	.transmit_chars = transmit_chars_putchar,
176 	.receive_chars = receive_chars_getchar,
177 };
178 
179 static const struct sunhv_ops bywrite_ops = {
180 	.transmit_chars = transmit_chars_write,
181 	.receive_chars = receive_chars_read,
182 };
183 
184 static const struct sunhv_ops *sunhv_ops = &bychar_ops;
185 
186 static struct tty_port *receive_chars(struct uart_port *port)
187 {
188 	struct tty_port *tport = NULL;
189 
190 	if (port->state != NULL)		/* Unopened serial console */
191 		tport = &port->state->port;
192 
193 	if (sunhv_ops->receive_chars(port))
194 		sun_do_break();
195 
196 	return tport;
197 }
198 
199 static void transmit_chars(struct uart_port *port)
200 {
201 	struct circ_buf *xmit;
202 
203 	if (!port->state)
204 		return;
205 
206 	xmit = &port->state->xmit;
207 	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
208 		return;
209 
210 	sunhv_ops->transmit_chars(port, xmit);
211 
212 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
213 		uart_write_wakeup(port);
214 }
215 
216 static irqreturn_t sunhv_interrupt(int irq, void *dev_id)
217 {
218 	struct uart_port *port = dev_id;
219 	struct tty_port *tport;
220 	unsigned long flags;
221 
222 	spin_lock_irqsave(&port->lock, flags);
223 	tport = receive_chars(port);
224 	transmit_chars(port);
225 	spin_unlock_irqrestore(&port->lock, flags);
226 
227 	if (tport)
228 		tty_flip_buffer_push(tport);
229 
230 	return IRQ_HANDLED;
231 }
232 
233 /* port->lock is not held.  */
234 static unsigned int sunhv_tx_empty(struct uart_port *port)
235 {
236 	/* Transmitter is always empty for us.  If the circ buffer
237 	 * is non-empty or there is an x_char pending, our caller
238 	 * will do the right thing and ignore what we return here.
239 	 */
240 	return TIOCSER_TEMT;
241 }
242 
243 /* port->lock held by caller.  */
244 static void sunhv_set_mctrl(struct uart_port *port, unsigned int mctrl)
245 {
246 	return;
247 }
248 
249 /* port->lock is held by caller and interrupts are disabled.  */
250 static unsigned int sunhv_get_mctrl(struct uart_port *port)
251 {
252 	return TIOCM_DSR | TIOCM_CAR | TIOCM_CTS;
253 }
254 
255 /* port->lock held by caller.  */
256 static void sunhv_stop_tx(struct uart_port *port)
257 {
258 	return;
259 }
260 
261 /* port->lock held by caller.  */
262 static void sunhv_start_tx(struct uart_port *port)
263 {
264 	transmit_chars(port);
265 }
266 
267 /* port->lock is not held.  */
268 static void sunhv_send_xchar(struct uart_port *port, char ch)
269 {
270 	unsigned long flags;
271 	int limit = 10000;
272 
273 	if (ch == __DISABLED_CHAR)
274 		return;
275 
276 	spin_lock_irqsave(&port->lock, flags);
277 
278 	while (limit-- > 0) {
279 		long status = sun4v_con_putchar(ch);
280 		if (status == HV_EOK)
281 			break;
282 		udelay(1);
283 	}
284 
285 	spin_unlock_irqrestore(&port->lock, flags);
286 }
287 
288 /* port->lock held by caller.  */
289 static void sunhv_stop_rx(struct uart_port *port)
290 {
291 }
292 
293 /* port->lock is not held.  */
294 static void sunhv_break_ctl(struct uart_port *port, int break_state)
295 {
296 	if (break_state) {
297 		unsigned long flags;
298 		int limit = 10000;
299 
300 		spin_lock_irqsave(&port->lock, flags);
301 
302 		while (limit-- > 0) {
303 			long status = sun4v_con_putchar(CON_BREAK);
304 			if (status == HV_EOK)
305 				break;
306 			udelay(1);
307 		}
308 
309 		spin_unlock_irqrestore(&port->lock, flags);
310 	}
311 }
312 
313 /* port->lock is not held.  */
314 static int sunhv_startup(struct uart_port *port)
315 {
316 	return 0;
317 }
318 
319 /* port->lock is not held.  */
320 static void sunhv_shutdown(struct uart_port *port)
321 {
322 }
323 
324 /* port->lock is not held.  */
325 static void sunhv_set_termios(struct uart_port *port, struct ktermios *termios,
326 			      struct ktermios *old)
327 {
328 	unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
329 	unsigned int quot = uart_get_divisor(port, baud);
330 	unsigned int iflag, cflag;
331 	unsigned long flags;
332 
333 	spin_lock_irqsave(&port->lock, flags);
334 
335 	iflag = termios->c_iflag;
336 	cflag = termios->c_cflag;
337 
338 	port->ignore_status_mask = 0;
339 	if (iflag & IGNBRK)
340 		port->ignore_status_mask |= IGNORE_BREAK;
341 	if ((cflag & CREAD) == 0)
342 		port->ignore_status_mask |= IGNORE_ALL;
343 
344 	/* XXX */
345 	uart_update_timeout(port, cflag,
346 			    (port->uartclk / (16 * quot)));
347 
348 	spin_unlock_irqrestore(&port->lock, flags);
349 }
350 
351 static const char *sunhv_type(struct uart_port *port)
352 {
353 	return "SUN4V HCONS";
354 }
355 
356 static void sunhv_release_port(struct uart_port *port)
357 {
358 }
359 
360 static int sunhv_request_port(struct uart_port *port)
361 {
362 	return 0;
363 }
364 
365 static void sunhv_config_port(struct uart_port *port, int flags)
366 {
367 }
368 
369 static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
370 {
371 	return -EINVAL;
372 }
373 
374 static const struct uart_ops sunhv_pops = {
375 	.tx_empty	= sunhv_tx_empty,
376 	.set_mctrl	= sunhv_set_mctrl,
377 	.get_mctrl	= sunhv_get_mctrl,
378 	.stop_tx	= sunhv_stop_tx,
379 	.start_tx	= sunhv_start_tx,
380 	.send_xchar	= sunhv_send_xchar,
381 	.stop_rx	= sunhv_stop_rx,
382 	.break_ctl	= sunhv_break_ctl,
383 	.startup	= sunhv_startup,
384 	.shutdown	= sunhv_shutdown,
385 	.set_termios	= sunhv_set_termios,
386 	.type		= sunhv_type,
387 	.release_port	= sunhv_release_port,
388 	.request_port	= sunhv_request_port,
389 	.config_port	= sunhv_config_port,
390 	.verify_port	= sunhv_verify_port,
391 };
392 
393 static struct uart_driver sunhv_reg = {
394 	.owner			= THIS_MODULE,
395 	.driver_name		= "sunhv",
396 	.dev_name		= "ttyHV",
397 	.major			= TTY_MAJOR,
398 };
399 
400 static struct uart_port *sunhv_port;
401 
402 void sunhv_migrate_hvcons_irq(int cpu)
403 {
404 	/* Migrate hvcons irq to param cpu */
405 	irq_force_affinity(sunhv_port->irq, cpumask_of(cpu));
406 }
407 
408 /* Copy 's' into the con_write_page, decoding "\n" into
409  * "\r\n" along the way.  We have to return two lengths
410  * because the caller needs to know how much to advance
411  * 's' and also how many bytes to output via con_write_page.
412  */
413 static int fill_con_write_page(const char *s, unsigned int n,
414 			       unsigned long *page_bytes)
415 {
416 	const char *orig_s = s;
417 	char *p = con_write_page;
418 	int left = PAGE_SIZE;
419 
420 	while (n--) {
421 		if (*s == '\n') {
422 			if (left < 2)
423 				break;
424 			*p++ = '\r';
425 			left--;
426 		} else if (left < 1)
427 			break;
428 		*p++ = *s++;
429 		left--;
430 	}
431 	*page_bytes = p - con_write_page;
432 	return s - orig_s;
433 }
434 
435 static void sunhv_console_write_paged(struct console *con, const char *s, unsigned n)
436 {
437 	struct uart_port *port = sunhv_port;
438 	unsigned long flags;
439 	int locked = 1;
440 
441 	if (port->sysrq || oops_in_progress)
442 		locked = spin_trylock_irqsave(&port->lock, flags);
443 	else
444 		spin_lock_irqsave(&port->lock, flags);
445 
446 	while (n > 0) {
447 		unsigned long ra = __pa(con_write_page);
448 		unsigned long page_bytes;
449 		unsigned int cpy = fill_con_write_page(s, n,
450 						       &page_bytes);
451 
452 		n -= cpy;
453 		s += cpy;
454 		while (page_bytes > 0) {
455 			unsigned long written;
456 			int limit = 1000000;
457 
458 			while (limit--) {
459 				unsigned long stat;
460 
461 				stat = sun4v_con_write(ra, page_bytes,
462 						       &written);
463 				if (stat == HV_EOK)
464 					break;
465 				udelay(1);
466 			}
467 			if (limit < 0)
468 				break;
469 			page_bytes -= written;
470 			ra += written;
471 		}
472 	}
473 
474 	if (locked)
475 		spin_unlock_irqrestore(&port->lock, flags);
476 }
477 
478 static inline void sunhv_console_putchar(struct uart_port *port, char c)
479 {
480 	int limit = 1000000;
481 
482 	while (limit-- > 0) {
483 		long status = sun4v_con_putchar(c);
484 		if (status == HV_EOK)
485 			break;
486 		udelay(1);
487 	}
488 }
489 
490 static void sunhv_console_write_bychar(struct console *con, const char *s, unsigned n)
491 {
492 	struct uart_port *port = sunhv_port;
493 	unsigned long flags;
494 	int i, locked = 1;
495 
496 	if (port->sysrq || oops_in_progress)
497 		locked = spin_trylock_irqsave(&port->lock, flags);
498 	else
499 		spin_lock_irqsave(&port->lock, flags);
500 
501 	for (i = 0; i < n; i++) {
502 		if (*s == '\n')
503 			sunhv_console_putchar(port, '\r');
504 		sunhv_console_putchar(port, *s++);
505 	}
506 
507 	if (locked)
508 		spin_unlock_irqrestore(&port->lock, flags);
509 }
510 
511 static struct console sunhv_console = {
512 	.name	=	"ttyHV",
513 	.write	=	sunhv_console_write_bychar,
514 	.device	=	uart_console_device,
515 	.flags	=	CON_PRINTBUFFER,
516 	.index	=	-1,
517 	.data	=	&sunhv_reg,
518 };
519 
520 static int hv_probe(struct platform_device *op)
521 {
522 	struct uart_port *port;
523 	unsigned long minor;
524 	int err;
525 
526 	if (op->archdata.irqs[0] == 0xffffffff)
527 		return -ENODEV;
528 
529 	port = kzalloc(sizeof(struct uart_port), GFP_KERNEL);
530 	if (unlikely(!port))
531 		return -ENOMEM;
532 
533 	minor = 1;
534 	if (sun4v_hvapi_register(HV_GRP_CORE, 1, &minor) == 0 &&
535 	    minor >= 1) {
536 		err = -ENOMEM;
537 		con_write_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
538 		if (!con_write_page)
539 			goto out_free_port;
540 
541 		con_read_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
542 		if (!con_read_page)
543 			goto out_free_con_write_page;
544 
545 		sunhv_console.write = sunhv_console_write_paged;
546 		sunhv_ops = &bywrite_ops;
547 	}
548 
549 	sunhv_port = port;
550 
551 	port->has_sysrq = 1;
552 	port->line = 0;
553 	port->ops = &sunhv_pops;
554 	port->type = PORT_SUNHV;
555 	port->uartclk = ( 29491200 / 16 ); /* arbitrary */
556 
557 	port->membase = (unsigned char __iomem *) __pa(port);
558 
559 	port->irq = op->archdata.irqs[0];
560 
561 	port->dev = &op->dev;
562 
563 	err = sunserial_register_minors(&sunhv_reg, 1);
564 	if (err)
565 		goto out_free_con_read_page;
566 
567 	sunserial_console_match(&sunhv_console, op->dev.of_node,
568 				&sunhv_reg, port->line, false);
569 
570 	/* We need to initialize lock even for non-registered console */
571 	spin_lock_init(&port->lock);
572 
573 	err = uart_add_one_port(&sunhv_reg, port);
574 	if (err)
575 		goto out_unregister_driver;
576 
577 	err = request_irq(port->irq, sunhv_interrupt, 0, "hvcons", port);
578 	if (err)
579 		goto out_remove_port;
580 
581 	platform_set_drvdata(op, port);
582 
583 	return 0;
584 
585 out_remove_port:
586 	uart_remove_one_port(&sunhv_reg, port);
587 
588 out_unregister_driver:
589 	sunserial_unregister_minors(&sunhv_reg, 1);
590 
591 out_free_con_read_page:
592 	kfree(con_read_page);
593 
594 out_free_con_write_page:
595 	kfree(con_write_page);
596 
597 out_free_port:
598 	kfree(port);
599 	sunhv_port = NULL;
600 	return err;
601 }
602 
603 static int hv_remove(struct platform_device *dev)
604 {
605 	struct uart_port *port = platform_get_drvdata(dev);
606 
607 	free_irq(port->irq, port);
608 
609 	uart_remove_one_port(&sunhv_reg, port);
610 
611 	sunserial_unregister_minors(&sunhv_reg, 1);
612 	kfree(con_read_page);
613 	kfree(con_write_page);
614 	kfree(port);
615 	sunhv_port = NULL;
616 
617 	return 0;
618 }
619 
620 static const struct of_device_id hv_match[] = {
621 	{
622 		.name = "console",
623 		.compatible = "qcn",
624 	},
625 	{
626 		.name = "console",
627 		.compatible = "SUNW,sun4v-console",
628 	},
629 	{},
630 };
631 
632 static struct platform_driver hv_driver = {
633 	.driver = {
634 		.name = "hv",
635 		.of_match_table = hv_match,
636 	},
637 	.probe		= hv_probe,
638 	.remove		= hv_remove,
639 };
640 
641 static int __init sunhv_init(void)
642 {
643 	if (tlb_type != hypervisor)
644 		return -ENODEV;
645 
646 	return platform_driver_register(&hv_driver);
647 }
648 device_initcall(sunhv_init);
649 
650 #if 0 /* ...def MODULE ; never supported as such */
651 MODULE_AUTHOR("David S. Miller");
652 MODULE_DESCRIPTION("SUN4V Hypervisor console driver");
653 MODULE_VERSION("2.0");
654 MODULE_LICENSE("GPL");
655 #endif
656