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
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		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
51		port->icount.tx++;
52	}
53}
54
55static 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
71static 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
114static 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
169struct sunhv_ops {
170	void (*transmit_chars)(struct uart_port *port, struct circ_buf *xmit);
171	int (*receive_chars)(struct uart_port *port);
172};
173
174static const struct sunhv_ops bychar_ops = {
175	.transmit_chars = transmit_chars_putchar,
176	.receive_chars = receive_chars_getchar,
177};
178
179static const struct sunhv_ops bywrite_ops = {
180	.transmit_chars = transmit_chars_write,
181	.receive_chars = receive_chars_read,
182};
183
184static const struct sunhv_ops *sunhv_ops = &bychar_ops;
185
186static 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
199static 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
216static 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.  */
234static 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.  */
244static 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.  */
250static 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.  */
256static void sunhv_stop_tx(struct uart_port *port)
257{
258	return;
259}
260
261/* port->lock held by caller.  */
262static void sunhv_start_tx(struct uart_port *port)
263{
264	transmit_chars(port);
265}
266
267/* port->lock is not held.  */
268static 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.  */
289static void sunhv_stop_rx(struct uart_port *port)
290{
291}
292
293/* port->lock is not held.  */
294static 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.  */
314static int sunhv_startup(struct uart_port *port)
315{
316	return 0;
317}
318
319/* port->lock is not held.  */
320static void sunhv_shutdown(struct uart_port *port)
321{
322}
323
324/* port->lock is not held.  */
325static 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
351static const char *sunhv_type(struct uart_port *port)
352{
353	return "SUN4V HCONS";
354}
355
356static void sunhv_release_port(struct uart_port *port)
357{
358}
359
360static int sunhv_request_port(struct uart_port *port)
361{
362	return 0;
363}
364
365static void sunhv_config_port(struct uart_port *port, int flags)
366{
367}
368
369static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
370{
371	return -EINVAL;
372}
373
374static 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
393static struct uart_driver sunhv_reg = {
394	.owner			= THIS_MODULE,
395	.driver_name		= "sunhv",
396	.dev_name		= "ttyHV",
397	.major			= TTY_MAJOR,
398};
399
400static struct uart_port *sunhv_port;
401
402void 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 */
413static 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
435static 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
478static 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
490static 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
511static 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
520static 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	err = uart_add_one_port(&sunhv_reg, port);
571	if (err)
572		goto out_unregister_driver;
573
574	err = request_irq(port->irq, sunhv_interrupt, 0, "hvcons", port);
575	if (err)
576		goto out_remove_port;
577
578	platform_set_drvdata(op, port);
579
580	return 0;
581
582out_remove_port:
583	uart_remove_one_port(&sunhv_reg, port);
584
585out_unregister_driver:
586	sunserial_unregister_minors(&sunhv_reg, 1);
587
588out_free_con_read_page:
589	kfree(con_read_page);
590
591out_free_con_write_page:
592	kfree(con_write_page);
593
594out_free_port:
595	kfree(port);
596	sunhv_port = NULL;
597	return err;
598}
599
600static int hv_remove(struct platform_device *dev)
601{
602	struct uart_port *port = platform_get_drvdata(dev);
603
604	free_irq(port->irq, port);
605
606	uart_remove_one_port(&sunhv_reg, port);
607
608	sunserial_unregister_minors(&sunhv_reg, 1);
609	kfree(con_read_page);
610	kfree(con_write_page);
611	kfree(port);
612	sunhv_port = NULL;
613
614	return 0;
615}
616
617static const struct of_device_id hv_match[] = {
618	{
619		.name = "console",
620		.compatible = "qcn",
621	},
622	{
623		.name = "console",
624		.compatible = "SUNW,sun4v-console",
625	},
626	{},
627};
628
629static struct platform_driver hv_driver = {
630	.driver = {
631		.name = "hv",
632		.of_match_table = hv_match,
633	},
634	.probe		= hv_probe,
635	.remove		= hv_remove,
636};
637
638static int __init sunhv_init(void)
639{
640	if (tlb_type != hypervisor)
641		return -ENODEV;
642
643	return platform_driver_register(&hv_driver);
644}
645device_initcall(sunhv_init);
646
647#if 0 /* ...def MODULE ; never supported as such */
648MODULE_AUTHOR("David S. Miller");
649MODULE_DESCRIPTION("SUN4V Hypervisor console driver");
650MODULE_VERSION("2.0");
651MODULE_LICENSE("GPL");
652#endif
653