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)
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
118static 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
167struct sunhv_ops {
168	void (*transmit_chars)(struct uart_port *port, struct circ_buf *xmit);
169	int (*receive_chars)(struct uart_port *port);
170};
171
172static struct sunhv_ops bychar_ops = {
173	.transmit_chars = transmit_chars_putchar,
174	.receive_chars = receive_chars_getchar,
175};
176
177static struct sunhv_ops bywrite_ops = {
178	.transmit_chars = transmit_chars_write,
179	.receive_chars = receive_chars_read,
180};
181
182static struct sunhv_ops *sunhv_ops = &bychar_ops;
183
184static 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
197static 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
214static 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.  */
232static 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.  */
242static 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.  */
248static 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.  */
254static void sunhv_stop_tx(struct uart_port *port)
255{
256	return;
257}
258
259/* port->lock held by caller.  */
260static void sunhv_start_tx(struct uart_port *port)
261{
262	transmit_chars(port);
263}
264
265/* port->lock is not held.  */
266static void sunhv_send_xchar(struct uart_port *port, char ch)
267{
268	unsigned long flags;
269	int limit = 10000;
270
271	if (ch == __DISABLED_CHAR)
272		return;
273
274	spin_lock_irqsave(&port->lock, flags);
275
276	while (limit-- > 0) {
277		long status = sun4v_con_putchar(ch);
278		if (status == HV_EOK)
279			break;
280		udelay(1);
281	}
282
283	spin_unlock_irqrestore(&port->lock, flags);
284}
285
286/* port->lock held by caller.  */
287static void sunhv_stop_rx(struct uart_port *port)
288{
289}
290
291/* port->lock is not held.  */
292static void sunhv_break_ctl(struct uart_port *port, int break_state)
293{
294	if (break_state) {
295		unsigned long flags;
296		int limit = 10000;
297
298		spin_lock_irqsave(&port->lock, flags);
299
300		while (limit-- > 0) {
301			long status = sun4v_con_putchar(CON_BREAK);
302			if (status == HV_EOK)
303				break;
304			udelay(1);
305		}
306
307		spin_unlock_irqrestore(&port->lock, flags);
308	}
309}
310
311/* port->lock is not held.  */
312static int sunhv_startup(struct uart_port *port)
313{
314	return 0;
315}
316
317/* port->lock is not held.  */
318static void sunhv_shutdown(struct uart_port *port)
319{
320}
321
322/* port->lock is not held.  */
323static void sunhv_set_termios(struct uart_port *port, struct ktermios *termios,
324			      struct ktermios *old)
325{
326	unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
327	unsigned int quot = uart_get_divisor(port, baud);
328	unsigned int iflag, cflag;
329	unsigned long flags;
330
331	spin_lock_irqsave(&port->lock, flags);
332
333	iflag = termios->c_iflag;
334	cflag = termios->c_cflag;
335
336	port->ignore_status_mask = 0;
337	if (iflag & IGNBRK)
338		port->ignore_status_mask |= IGNORE_BREAK;
339	if ((cflag & CREAD) == 0)
340		port->ignore_status_mask |= IGNORE_ALL;
341
342	/* XXX */
343	uart_update_timeout(port, cflag,
344			    (port->uartclk / (16 * quot)));
345
346	spin_unlock_irqrestore(&port->lock, flags);
347}
348
349static const char *sunhv_type(struct uart_port *port)
350{
351	return "SUN4V HCONS";
352}
353
354static void sunhv_release_port(struct uart_port *port)
355{
356}
357
358static int sunhv_request_port(struct uart_port *port)
359{
360	return 0;
361}
362
363static void sunhv_config_port(struct uart_port *port, int flags)
364{
365}
366
367static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
368{
369	return -EINVAL;
370}
371
372static struct uart_ops sunhv_pops = {
373	.tx_empty	= sunhv_tx_empty,
374	.set_mctrl	= sunhv_set_mctrl,
375	.get_mctrl	= sunhv_get_mctrl,
376	.stop_tx	= sunhv_stop_tx,
377	.start_tx	= sunhv_start_tx,
378	.send_xchar	= sunhv_send_xchar,
379	.stop_rx	= sunhv_stop_rx,
380	.break_ctl	= sunhv_break_ctl,
381	.startup	= sunhv_startup,
382	.shutdown	= sunhv_shutdown,
383	.set_termios	= sunhv_set_termios,
384	.type		= sunhv_type,
385	.release_port	= sunhv_release_port,
386	.request_port	= sunhv_request_port,
387	.config_port	= sunhv_config_port,
388	.verify_port	= sunhv_verify_port,
389};
390
391static struct uart_driver sunhv_reg = {
392	.owner			= THIS_MODULE,
393	.driver_name		= "sunhv",
394	.dev_name		= "ttyS",
395	.major			= TTY_MAJOR,
396};
397
398static struct uart_port *sunhv_port;
399
400/* Copy 's' into the con_write_page, decoding "\n" into
401 * "\r\n" along the way.  We have to return two lengths
402 * because the caller needs to know how much to advance
403 * 's' and also how many bytes to output via con_write_page.
404 */
405static int fill_con_write_page(const char *s, unsigned int n,
406			       unsigned long *page_bytes)
407{
408	const char *orig_s = s;
409	char *p = con_write_page;
410	int left = PAGE_SIZE;
411
412	while (n--) {
413		if (*s == '\n') {
414			if (left < 2)
415				break;
416			*p++ = '\r';
417			left--;
418		} else if (left < 1)
419			break;
420		*p++ = *s++;
421		left--;
422	}
423	*page_bytes = p - con_write_page;
424	return s - orig_s;
425}
426
427static void sunhv_console_write_paged(struct console *con, const char *s, unsigned n)
428{
429	struct uart_port *port = sunhv_port;
430	unsigned long flags;
431	int locked = 1;
432
433	if (port->sysrq || oops_in_progress)
434		locked = spin_trylock_irqsave(&port->lock, flags);
435	else
436		spin_lock_irqsave(&port->lock, flags);
437
438	while (n > 0) {
439		unsigned long ra = __pa(con_write_page);
440		unsigned long page_bytes;
441		unsigned int cpy = fill_con_write_page(s, n,
442						       &page_bytes);
443
444		n -= cpy;
445		s += cpy;
446		while (page_bytes > 0) {
447			unsigned long written;
448			int limit = 1000000;
449
450			while (limit--) {
451				unsigned long stat;
452
453				stat = sun4v_con_write(ra, page_bytes,
454						       &written);
455				if (stat == HV_EOK)
456					break;
457				udelay(1);
458			}
459			if (limit < 0)
460				break;
461			page_bytes -= written;
462			ra += written;
463		}
464	}
465
466	if (locked)
467		spin_unlock_irqrestore(&port->lock, flags);
468}
469
470static inline void sunhv_console_putchar(struct uart_port *port, char c)
471{
472	int limit = 1000000;
473
474	while (limit-- > 0) {
475		long status = sun4v_con_putchar(c);
476		if (status == HV_EOK)
477			break;
478		udelay(1);
479	}
480}
481
482static void sunhv_console_write_bychar(struct console *con, const char *s, unsigned n)
483{
484	struct uart_port *port = sunhv_port;
485	unsigned long flags;
486	int i, locked = 1;
487
488	if (port->sysrq || oops_in_progress)
489		locked = spin_trylock_irqsave(&port->lock, flags);
490	else
491		spin_lock_irqsave(&port->lock, flags);
492	if (port->sysrq) {
493		locked = 0;
494	} else if (oops_in_progress) {
495		locked = spin_trylock(&port->lock);
496	} else
497		spin_lock(&port->lock);
498
499	for (i = 0; i < n; i++) {
500		if (*s == '\n')
501			sunhv_console_putchar(port, '\r');
502		sunhv_console_putchar(port, *s++);
503	}
504
505	if (locked)
506		spin_unlock_irqrestore(&port->lock, flags);
507}
508
509static struct console sunhv_console = {
510	.name	=	"ttyHV",
511	.write	=	sunhv_console_write_bychar,
512	.device	=	uart_console_device,
513	.flags	=	CON_PRINTBUFFER,
514	.index	=	-1,
515	.data	=	&sunhv_reg,
516};
517
518static int hv_probe(struct platform_device *op)
519{
520	struct uart_port *port;
521	unsigned long minor;
522	int err;
523
524	if (op->archdata.irqs[0] == 0xffffffff)
525		return -ENODEV;
526
527	port = kzalloc(sizeof(struct uart_port), GFP_KERNEL);
528	if (unlikely(!port))
529		return -ENOMEM;
530
531	minor = 1;
532	if (sun4v_hvapi_register(HV_GRP_CORE, 1, &minor) == 0 &&
533	    minor >= 1) {
534		err = -ENOMEM;
535		con_write_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
536		if (!con_write_page)
537			goto out_free_port;
538
539		con_read_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
540		if (!con_read_page)
541			goto out_free_con_write_page;
542
543		sunhv_console.write = sunhv_console_write_paged;
544		sunhv_ops = &bywrite_ops;
545	}
546
547	sunhv_port = port;
548
549	port->line = 0;
550	port->ops = &sunhv_pops;
551	port->type = PORT_SUNHV;
552	port->uartclk = ( 29491200 / 16 ); /* arbitrary */
553
554	port->membase = (unsigned char __iomem *) __pa(port);
555
556	port->irq = op->archdata.irqs[0];
557
558	port->dev = &op->dev;
559
560	err = sunserial_register_minors(&sunhv_reg, 1);
561	if (err)
562		goto out_free_con_read_page;
563
564	sunserial_console_match(&sunhv_console, op->dev.of_node,
565				&sunhv_reg, port->line, false);
566
567	err = uart_add_one_port(&sunhv_reg, port);
568	if (err)
569		goto out_unregister_driver;
570
571	err = request_irq(port->irq, sunhv_interrupt, 0, "hvcons", port);
572	if (err)
573		goto out_remove_port;
574
575	platform_set_drvdata(op, port);
576
577	return 0;
578
579out_remove_port:
580	uart_remove_one_port(&sunhv_reg, port);
581
582out_unregister_driver:
583	sunserial_unregister_minors(&sunhv_reg, 1);
584
585out_free_con_read_page:
586	kfree(con_read_page);
587
588out_free_con_write_page:
589	kfree(con_write_page);
590
591out_free_port:
592	kfree(port);
593	sunhv_port = NULL;
594	return err;
595}
596
597static int hv_remove(struct platform_device *dev)
598{
599	struct uart_port *port = platform_get_drvdata(dev);
600
601	free_irq(port->irq, port);
602
603	uart_remove_one_port(&sunhv_reg, port);
604
605	sunserial_unregister_minors(&sunhv_reg, 1);
606
607	kfree(port);
608	sunhv_port = NULL;
609
610	return 0;
611}
612
613static const struct of_device_id hv_match[] = {
614	{
615		.name = "console",
616		.compatible = "qcn",
617	},
618	{
619		.name = "console",
620		.compatible = "SUNW,sun4v-console",
621	},
622	{},
623};
624MODULE_DEVICE_TABLE(of, hv_match);
625
626static struct platform_driver hv_driver = {
627	.driver = {
628		.name = "hv",
629		.of_match_table = hv_match,
630	},
631	.probe		= hv_probe,
632	.remove		= hv_remove,
633};
634
635static int __init sunhv_init(void)
636{
637	if (tlb_type != hypervisor)
638		return -ENODEV;
639
640	return platform_driver_register(&hv_driver);
641}
642
643static void __exit sunhv_exit(void)
644{
645	platform_driver_unregister(&hv_driver);
646}
647
648module_init(sunhv_init);
649module_exit(sunhv_exit);
650
651MODULE_AUTHOR("David S. Miller");
652MODULE_DESCRIPTION("SUN4V Hypervisor console driver");
653MODULE_VERSION("2.0");
654MODULE_LICENSE("GPL");
655