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.h>
21#include <linux/platform_device.h>
22
23#include <asm/hypervisor.h>
24#include <asm/spitfire.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
37static char *con_write_page;
38static char *con_read_page;
39
40static int hung_up = 0;
41
42static 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		uart_xmit_advance(port, 1);
51	}
52}
53
54static void transmit_chars_write(struct uart_port *port, struct circ_buf *xmit)
55{
56	while (!uart_circ_empty(xmit)) {
57		unsigned long ra = __pa(xmit->buf + xmit->tail);
58		unsigned long len, status, sent;
59
60		len = CIRC_CNT_TO_END(xmit->head, xmit->tail,
61				      UART_XMIT_SIZE);
62		status = sun4v_con_write(ra, len, &sent);
63		if (status != HV_EOK)
64			break;
65		uart_xmit_advance(port, sent);
66	}
67}
68
69static int receive_chars_getchar(struct uart_port *port)
70{
71	int saw_console_brk = 0;
72	int limit = 10000;
73
74	while (limit-- > 0) {
75		long status;
76		long c = sun4v_con_getchar(&status);
77
78		if (status == HV_EWOULDBLOCK)
79			break;
80
81		if (c == CON_BREAK) {
82			if (uart_handle_break(port))
83				continue;
84			saw_console_brk = 1;
85			c = 0;
86		}
87
88		if (c == CON_HUP) {
89			hung_up = 1;
90			uart_handle_dcd_change(port, false);
91		} else if (hung_up) {
92			hung_up = 0;
93			uart_handle_dcd_change(port, true);
94		}
95
96		if (port->state == NULL) {
97			uart_handle_sysrq_char(port, c);
98			continue;
99		}
100
101		port->icount.rx++;
102
103		if (uart_handle_sysrq_char(port, c))
104			continue;
105
106		tty_insert_flip_char(&port->state->port, c, TTY_NORMAL);
107	}
108
109	return saw_console_brk;
110}
111
112static int receive_chars_read(struct uart_port *port)
113{
114	static int saw_console_brk;
115	int limit = 10000;
116
117	while (limit-- > 0) {
118		unsigned long ra = __pa(con_read_page);
119		unsigned long bytes_read, i;
120		long stat = sun4v_con_read(ra, PAGE_SIZE, &bytes_read);
121
122		if (stat != HV_EOK) {
123			bytes_read = 0;
124
125			if (stat == CON_BREAK) {
126				if (saw_console_brk)
127					sun_do_break();
128
129				if (uart_handle_break(port))
130					continue;
131				saw_console_brk = 1;
132				*con_read_page = 0;
133				bytes_read = 1;
134			} else if (stat == CON_HUP) {
135				hung_up = 1;
136				uart_handle_dcd_change(port, false);
137				continue;
138			} else {
139				/* HV_EWOULDBLOCK, etc.  */
140				break;
141			}
142		}
143
144		if (hung_up) {
145			hung_up = 0;
146			uart_handle_dcd_change(port, true);
147		}
148
149		if (port->sysrq != 0 &&  *con_read_page) {
150			for (i = 0; i < bytes_read; i++)
151				uart_handle_sysrq_char(port, con_read_page[i]);
152			saw_console_brk = 0;
153		}
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 const struct sunhv_ops bychar_ops = {
173	.transmit_chars = transmit_chars_putchar,
174	.receive_chars = receive_chars_getchar,
175};
176
177static const struct sunhv_ops bywrite_ops = {
178	.transmit_chars = transmit_chars_write,
179	.receive_chars = receive_chars_read,
180};
181
182static const 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	uart_port_lock_irqsave(port, &flags);
221	tport = receive_chars(port);
222	transmit_chars(port);
223	uart_port_unlock_irqrestore(port, 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	uart_port_lock_irqsave(port, &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	uart_port_unlock_irqrestore(port, 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		uart_port_lock_irqsave(port, &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		uart_port_unlock_irqrestore(port, 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			      const 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	uart_port_lock_irqsave(port, &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	uart_port_unlock_irqrestore(port, 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 const 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		= "ttyHV",
395	.major			= TTY_MAJOR,
396};
397
398static struct uart_port *sunhv_port;
399
400void sunhv_migrate_hvcons_irq(int cpu)
401{
402	/* Migrate hvcons irq to param cpu */
403	irq_force_affinity(sunhv_port->irq, cpumask_of(cpu));
404}
405
406/* Copy 's' into the con_write_page, decoding "\n" into
407 * "\r\n" along the way.  We have to return two lengths
408 * because the caller needs to know how much to advance
409 * 's' and also how many bytes to output via con_write_page.
410 */
411static int fill_con_write_page(const char *s, unsigned int n,
412			       unsigned long *page_bytes)
413{
414	const char *orig_s = s;
415	char *p = con_write_page;
416	int left = PAGE_SIZE;
417
418	while (n--) {
419		if (*s == '\n') {
420			if (left < 2)
421				break;
422			*p++ = '\r';
423			left--;
424		} else if (left < 1)
425			break;
426		*p++ = *s++;
427		left--;
428	}
429	*page_bytes = p - con_write_page;
430	return s - orig_s;
431}
432
433static void sunhv_console_write_paged(struct console *con, const char *s, unsigned n)
434{
435	struct uart_port *port = sunhv_port;
436	unsigned long flags;
437	int locked = 1;
438
439	if (port->sysrq || oops_in_progress)
440		locked = uart_port_trylock_irqsave(port, &flags);
441	else
442		uart_port_lock_irqsave(port, &flags);
443
444	while (n > 0) {
445		unsigned long ra = __pa(con_write_page);
446		unsigned long page_bytes;
447		unsigned int cpy = fill_con_write_page(s, n,
448						       &page_bytes);
449
450		n -= cpy;
451		s += cpy;
452		while (page_bytes > 0) {
453			unsigned long written;
454			int limit = 1000000;
455
456			while (limit--) {
457				unsigned long stat;
458
459				stat = sun4v_con_write(ra, page_bytes,
460						       &written);
461				if (stat == HV_EOK)
462					break;
463				udelay(1);
464			}
465			if (limit < 0)
466				break;
467			page_bytes -= written;
468			ra += written;
469		}
470	}
471
472	if (locked)
473		uart_port_unlock_irqrestore(port, 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	if (port->sysrq || oops_in_progress)
495		locked = uart_port_trylock_irqsave(port, &flags);
496	else
497		uart_port_lock_irqsave(port, &flags);
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		uart_port_unlock_irqrestore(port, 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->has_sysrq = 1;
550	port->line = 0;
551	port->ops = &sunhv_pops;
552	port->type = PORT_SUNHV;
553	port->uartclk = ( 29491200 / 16 ); /* arbitrary */
554
555	port->membase = (unsigned char __iomem *) __pa(port);
556
557	port->irq = op->archdata.irqs[0];
558
559	port->dev = &op->dev;
560
561	err = sunserial_register_minors(&sunhv_reg, 1);
562	if (err)
563		goto out_free_con_read_page;
564
565	sunserial_console_match(&sunhv_console, op->dev.of_node,
566				&sunhv_reg, port->line, false);
567
568	err = uart_add_one_port(&sunhv_reg, port);
569	if (err)
570		goto out_unregister_driver;
571
572	err = request_irq(port->irq, sunhv_interrupt, 0, "hvcons", port);
573	if (err)
574		goto out_remove_port;
575
576	platform_set_drvdata(op, port);
577
578	return 0;
579
580out_remove_port:
581	uart_remove_one_port(&sunhv_reg, port);
582
583out_unregister_driver:
584	sunserial_unregister_minors(&sunhv_reg, 1);
585
586out_free_con_read_page:
587	kfree(con_read_page);
588
589out_free_con_write_page:
590	kfree(con_write_page);
591
592out_free_port:
593	kfree(port);
594	sunhv_port = NULL;
595	return err;
596}
597
598static void hv_remove(struct platform_device *dev)
599{
600	struct uart_port *port = platform_get_drvdata(dev);
601
602	free_irq(port->irq, port);
603
604	uart_remove_one_port(&sunhv_reg, port);
605
606	sunserial_unregister_minors(&sunhv_reg, 1);
607	kfree(con_read_page);
608	kfree(con_write_page);
609	kfree(port);
610	sunhv_port = NULL;
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};
624
625static struct platform_driver hv_driver = {
626	.driver = {
627		.name = "hv",
628		.of_match_table = hv_match,
629	},
630	.probe		= hv_probe,
631	.remove_new	= hv_remove,
632};
633
634static int __init sunhv_init(void)
635{
636	if (tlb_type != hypervisor)
637		return -ENODEV;
638
639	return platform_driver_register(&hv_driver);
640}
641device_initcall(sunhv_init);
642
643#if 0 /* ...def MODULE ; never supported as such */
644MODULE_AUTHOR("David S. Miller");
645MODULE_DESCRIPTION("SUN4V Hypervisor console driver");
646MODULE_VERSION("2.0");
647MODULE_LICENSE("GPL");
648#endif
649