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
41static char *con_write_page;
42static char *con_read_page;
43
44static int hung_up = 0;
45
46static 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
59static 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
75static int receive_chars_getchar(struct uart_port *port, struct tty_struct *tty)
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 (tty == 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(tty, c, TTY_NORMAL);
113	}
114
115	return saw_console_brk;
116}
117
118static int receive_chars_read(struct uart_port *port, struct tty_struct *tty)
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 (tty == NULL)
156			continue;
157
158		port->icount.rx += bytes_read;
159
160		tty_insert_flip_string(tty, con_read_page, bytes_read);
161	}
162
163	return saw_console_brk;
164}
165
166struct sunhv_ops {
167	void (*transmit_chars)(struct uart_port *port, struct circ_buf *xmit);
168	int (*receive_chars)(struct uart_port *port, struct tty_struct *tty);
169};
170
171static struct sunhv_ops bychar_ops = {
172	.transmit_chars = transmit_chars_putchar,
173	.receive_chars = receive_chars_getchar,
174};
175
176static struct sunhv_ops bywrite_ops = {
177	.transmit_chars = transmit_chars_write,
178	.receive_chars = receive_chars_read,
179};
180
181static struct sunhv_ops *sunhv_ops = &bychar_ops;
182
183static struct tty_struct *receive_chars(struct uart_port *port)
184{
185	struct tty_struct *tty = NULL;
186
187	if (port->state != NULL)		/* Unopened serial console */
188		tty = port->state->port.tty;
189
190	if (sunhv_ops->receive_chars(port, tty))
191		sun_do_break();
192
193	return tty;
194}
195
196static 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
213static irqreturn_t sunhv_interrupt(int irq, void *dev_id)
214{
215	struct uart_port *port = dev_id;
216	struct tty_struct *tty;
217	unsigned long flags;
218
219	spin_lock_irqsave(&port->lock, flags);
220	tty = receive_chars(port);
221	transmit_chars(port);
222	spin_unlock_irqrestore(&port->lock, flags);
223
224	if (tty)
225		tty_flip_buffer_push(tty);
226
227	return IRQ_HANDLED;
228}
229
230/* port->lock is not held.  */
231static 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.  */
241static 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.  */
247static 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.  */
253static void sunhv_stop_tx(struct uart_port *port)
254{
255	return;
256}
257
258/* port->lock held by caller.  */
259static void sunhv_start_tx(struct uart_port *port)
260{
261	transmit_chars(port);
262}
263
264/* port->lock is not held.  */
265static void sunhv_send_xchar(struct uart_port *port, char ch)
266{
267	unsigned long flags;
268	int limit = 10000;
269
270	spin_lock_irqsave(&port->lock, flags);
271
272	while (limit-- > 0) {
273		long status = sun4v_con_putchar(ch);
274		if (status == HV_EOK)
275			break;
276		udelay(1);
277	}
278
279	spin_unlock_irqrestore(&port->lock, flags);
280}
281
282/* port->lock held by caller.  */
283static void sunhv_stop_rx(struct uart_port *port)
284{
285}
286
287/* port->lock held by caller.  */
288static void sunhv_enable_ms(struct uart_port *port)
289{
290}
291
292/* port->lock is not held.  */
293static void sunhv_break_ctl(struct uart_port *port, int break_state)
294{
295	if (break_state) {
296		unsigned long flags;
297		int limit = 10000;
298
299		spin_lock_irqsave(&port->lock, flags);
300
301		while (limit-- > 0) {
302			long status = sun4v_con_putchar(CON_BREAK);
303			if (status == HV_EOK)
304				break;
305			udelay(1);
306		}
307
308		spin_unlock_irqrestore(&port->lock, flags);
309	}
310}
311
312/* port->lock is not held.  */
313static int sunhv_startup(struct uart_port *port)
314{
315	return 0;
316}
317
318/* port->lock is not held.  */
319static void sunhv_shutdown(struct uart_port *port)
320{
321}
322
323/* port->lock is not held.  */
324static void sunhv_set_termios(struct uart_port *port, struct ktermios *termios,
325			      struct ktermios *old)
326{
327	unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
328	unsigned int quot = uart_get_divisor(port, baud);
329	unsigned int iflag, cflag;
330	unsigned long flags;
331
332	spin_lock_irqsave(&port->lock, flags);
333
334	iflag = termios->c_iflag;
335	cflag = termios->c_cflag;
336
337	port->ignore_status_mask = 0;
338	if (iflag & IGNBRK)
339		port->ignore_status_mask |= IGNORE_BREAK;
340	if ((cflag & CREAD) == 0)
341		port->ignore_status_mask |= IGNORE_ALL;
342
343	/* XXX */
344	uart_update_timeout(port, cflag,
345			    (port->uartclk / (16 * quot)));
346
347	spin_unlock_irqrestore(&port->lock, flags);
348}
349
350static const char *sunhv_type(struct uart_port *port)
351{
352	return "SUN4V HCONS";
353}
354
355static void sunhv_release_port(struct uart_port *port)
356{
357}
358
359static int sunhv_request_port(struct uart_port *port)
360{
361	return 0;
362}
363
364static void sunhv_config_port(struct uart_port *port, int flags)
365{
366}
367
368static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
369{
370	return -EINVAL;
371}
372
373static struct uart_ops sunhv_pops = {
374	.tx_empty	= sunhv_tx_empty,
375	.set_mctrl	= sunhv_set_mctrl,
376	.get_mctrl	= sunhv_get_mctrl,
377	.stop_tx	= sunhv_stop_tx,
378	.start_tx	= sunhv_start_tx,
379	.send_xchar	= sunhv_send_xchar,
380	.stop_rx	= sunhv_stop_rx,
381	.enable_ms	= sunhv_enable_ms,
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
393static struct uart_driver sunhv_reg = {
394	.owner			= THIS_MODULE,
395	.driver_name		= "sunhv",
396	.dev_name		= "ttyS",
397	.major			= TTY_MAJOR,
398};
399
400static struct uart_port *sunhv_port;
401
402/* Copy 's' into the con_write_page, decoding "\n" into
403 * "\r\n" along the way.  We have to return two lengths
404 * because the caller needs to know how much to advance
405 * 's' and also how many bytes to output via con_write_page.
406 */
407static int fill_con_write_page(const char *s, unsigned int n,
408			       unsigned long *page_bytes)
409{
410	const char *orig_s = s;
411	char *p = con_write_page;
412	int left = PAGE_SIZE;
413
414	while (n--) {
415		if (*s == '\n') {
416			if (left < 2)
417				break;
418			*p++ = '\r';
419			left--;
420		} else if (left < 1)
421			break;
422		*p++ = *s++;
423		left--;
424	}
425	*page_bytes = p - con_write_page;
426	return s - orig_s;
427}
428
429static void sunhv_console_write_paged(struct console *con, const char *s, unsigned n)
430{
431	struct uart_port *port = sunhv_port;
432	unsigned long flags;
433	int locked = 1;
434
435	local_irq_save(flags);
436	if (port->sysrq) {
437		locked = 0;
438	} else if (oops_in_progress) {
439		locked = spin_trylock(&port->lock);
440	} else
441		spin_lock(&port->lock);
442
443	while (n > 0) {
444		unsigned long ra = __pa(con_write_page);
445		unsigned long page_bytes;
446		unsigned int cpy = fill_con_write_page(s, n,
447						       &page_bytes);
448
449		n -= cpy;
450		s += cpy;
451		while (page_bytes > 0) {
452			unsigned long written;
453			int limit = 1000000;
454
455			while (limit--) {
456				unsigned long stat;
457
458				stat = sun4v_con_write(ra, page_bytes,
459						       &written);
460				if (stat == HV_EOK)
461					break;
462				udelay(1);
463			}
464			if (limit < 0)
465				break;
466			page_bytes -= written;
467			ra += written;
468		}
469	}
470
471	if (locked)
472		spin_unlock(&port->lock);
473	local_irq_restore(flags);
474}
475
476static inline void sunhv_console_putchar(struct uart_port *port, char c)
477{
478	int limit = 1000000;
479
480	while (limit-- > 0) {
481		long status = sun4v_con_putchar(c);
482		if (status == HV_EOK)
483			break;
484		udelay(1);
485	}
486}
487
488static void sunhv_console_write_bychar(struct console *con, const char *s, unsigned n)
489{
490	struct uart_port *port = sunhv_port;
491	unsigned long flags;
492	int i, locked = 1;
493
494	local_irq_save(flags);
495	if (port->sysrq) {
496		locked = 0;
497	} else if (oops_in_progress) {
498		locked = spin_trylock(&port->lock);
499	} else
500		spin_lock(&port->lock);
501
502	for (i = 0; i < n; i++) {
503		if (*s == '\n')
504			sunhv_console_putchar(port, '\r');
505		sunhv_console_putchar(port, *s++);
506	}
507
508	if (locked)
509		spin_unlock(&port->lock);
510	local_irq_restore(flags);
511}
512
513static struct console sunhv_console = {
514	.name	=	"ttyHV",
515	.write	=	sunhv_console_write_bychar,
516	.device	=	uart_console_device,
517	.flags	=	CON_PRINTBUFFER,
518	.index	=	-1,
519	.data	=	&sunhv_reg,
520};
521
522static int __devinit hv_probe(struct platform_device *op)
523{
524	struct uart_port *port;
525	unsigned long minor;
526	int err;
527
528	if (op->archdata.irqs[0] == 0xffffffff)
529		return -ENODEV;
530
531	port = kzalloc(sizeof(struct uart_port), GFP_KERNEL);
532	if (unlikely(!port))
533		return -ENOMEM;
534
535	minor = 1;
536	if (sun4v_hvapi_register(HV_GRP_CORE, 1, &minor) == 0 &&
537	    minor >= 1) {
538		err = -ENOMEM;
539		con_write_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
540		if (!con_write_page)
541			goto out_free_port;
542
543		con_read_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
544		if (!con_read_page)
545			goto out_free_con_write_page;
546
547		sunhv_console.write = sunhv_console_write_paged;
548		sunhv_ops = &bywrite_ops;
549	}
550
551	sunhv_port = port;
552
553	port->line = 0;
554	port->ops = &sunhv_pops;
555	port->type = PORT_SUNHV;
556	port->uartclk = ( 29491200 / 16 ); /* arbitrary */
557
558	port->membase = (unsigned char __iomem *) __pa(port);
559
560	port->irq = op->archdata.irqs[0];
561
562	port->dev = &op->dev;
563
564	err = sunserial_register_minors(&sunhv_reg, 1);
565	if (err)
566		goto out_free_con_read_page;
567
568	sunserial_console_match(&sunhv_console, op->dev.of_node,
569				&sunhv_reg, port->line, false);
570
571	err = uart_add_one_port(&sunhv_reg, port);
572	if (err)
573		goto out_unregister_driver;
574
575	err = request_irq(port->irq, sunhv_interrupt, 0, "hvcons", port);
576	if (err)
577		goto out_remove_port;
578
579	dev_set_drvdata(&op->dev, port);
580
581	return 0;
582
583out_remove_port:
584	uart_remove_one_port(&sunhv_reg, port);
585
586out_unregister_driver:
587	sunserial_unregister_minors(&sunhv_reg, 1);
588
589out_free_con_read_page:
590	kfree(con_read_page);
591
592out_free_con_write_page:
593	kfree(con_write_page);
594
595out_free_port:
596	kfree(port);
597	sunhv_port = NULL;
598	return err;
599}
600
601static int __devexit hv_remove(struct platform_device *dev)
602{
603	struct uart_port *port = dev_get_drvdata(&dev->dev);
604
605	free_irq(port->irq, port);
606
607	uart_remove_one_port(&sunhv_reg, port);
608
609	sunserial_unregister_minors(&sunhv_reg, 1);
610
611	kfree(port);
612	sunhv_port = NULL;
613
614	dev_set_drvdata(&dev->dev, NULL);
615
616	return 0;
617}
618
619static const struct of_device_id hv_match[] = {
620	{
621		.name = "console",
622		.compatible = "qcn",
623	},
624	{
625		.name = "console",
626		.compatible = "SUNW,sun4v-console",
627	},
628	{},
629};
630MODULE_DEVICE_TABLE(of, hv_match);
631
632static struct platform_driver hv_driver = {
633	.driver = {
634		.name = "hv",
635		.owner = THIS_MODULE,
636		.of_match_table = hv_match,
637	},
638	.probe		= hv_probe,
639	.remove		= __devexit_p(hv_remove),
640};
641
642static int __init sunhv_init(void)
643{
644	if (tlb_type != hypervisor)
645		return -ENODEV;
646
647	return platform_driver_register(&hv_driver);
648}
649
650static void __exit sunhv_exit(void)
651{
652	platform_driver_unregister(&hv_driver);
653}
654
655module_init(sunhv_init);
656module_exit(sunhv_exit);
657
658MODULE_AUTHOR("David S. Miller");
659MODULE_DESCRIPTION("SUN4V Hypervisor console driver");
660MODULE_VERSION("2.0");
661MODULE_LICENSE("GPL");
662