xref: /linux/drivers/tty/hvc/hvsi.c (revision a1c613ae4c322ddd58d5a8539dbfba2a0380a8c0)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (C) 2004 Hollis Blanchard <hollisb@us.ibm.com>, IBM
4  */
5 
6 /* Host Virtual Serial Interface (HVSI) is a protocol between the hosted OS
7  * and the service processor on IBM pSeries servers. On these servers, there
8  * are no serial ports under the OS's control, and sometimes there is no other
9  * console available either. However, the service processor has two standard
10  * serial ports, so this over-complicated protocol allows the OS to control
11  * those ports by proxy.
12  *
13  * Besides data, the procotol supports the reading/writing of the serial
14  * port's DTR line, and the reading of the CD line. This is to allow the OS to
15  * control a modem attached to the service processor's serial port. Note that
16  * the OS cannot change the speed of the port through this protocol.
17  */
18 
19 #undef DEBUG
20 
21 #include <linux/console.h>
22 #include <linux/ctype.h>
23 #include <linux/delay.h>
24 #include <linux/init.h>
25 #include <linux/interrupt.h>
26 #include <linux/module.h>
27 #include <linux/major.h>
28 #include <linux/kernel.h>
29 #include <linux/of_irq.h>
30 #include <linux/spinlock.h>
31 #include <linux/sysrq.h>
32 #include <linux/tty.h>
33 #include <linux/tty_flip.h>
34 #include <asm/hvcall.h>
35 #include <asm/hvconsole.h>
36 #include <linux/uaccess.h>
37 #include <asm/vio.h>
38 #include <asm/param.h>
39 #include <asm/hvsi.h>
40 
41 #define HVSI_MAJOR	229
42 #define HVSI_MINOR	128
43 #define MAX_NR_HVSI_CONSOLES 4
44 
45 #define HVSI_TIMEOUT (5*HZ)
46 #define HVSI_VERSION 1
47 #define HVSI_MAX_PACKET 256
48 #define HVSI_MAX_READ 16
49 #define HVSI_MAX_OUTGOING_DATA 12
50 #define N_OUTBUF 12
51 
52 /*
53  * we pass data via two 8-byte registers, so we would like our char arrays
54  * properly aligned for those loads.
55  */
56 #define __ALIGNED__	__attribute__((__aligned__(sizeof(long))))
57 
58 struct hvsi_struct {
59 	struct tty_port port;
60 	struct delayed_work writer;
61 	struct work_struct handshaker;
62 	wait_queue_head_t emptyq; /* woken when outbuf is emptied */
63 	wait_queue_head_t stateq; /* woken when HVSI state changes */
64 	spinlock_t lock;
65 	int index;
66 	uint8_t throttle_buf[128];
67 	uint8_t outbuf[N_OUTBUF]; /* to implement write_room and chars_in_buffer */
68 	/* inbuf is for packet reassembly. leave a little room for leftovers. */
69 	uint8_t inbuf[HVSI_MAX_PACKET + HVSI_MAX_READ];
70 	uint8_t *inbuf_end;
71 	int n_throttle;
72 	int n_outbuf;
73 	uint32_t vtermno;
74 	uint32_t virq;
75 	atomic_t seqno; /* HVSI packet sequence number */
76 	uint16_t mctrl;
77 	uint8_t state;  /* HVSI protocol state */
78 	uint8_t flags;
79 #ifdef CONFIG_MAGIC_SYSRQ
80 	uint8_t sysrq;
81 #endif /* CONFIG_MAGIC_SYSRQ */
82 };
83 static struct hvsi_struct hvsi_ports[MAX_NR_HVSI_CONSOLES];
84 
85 static struct tty_driver *hvsi_driver;
86 static int hvsi_count;
87 static int (*hvsi_wait)(struct hvsi_struct *hp, int state);
88 
89 enum HVSI_PROTOCOL_STATE {
90 	HVSI_CLOSED,
91 	HVSI_WAIT_FOR_VER_RESPONSE,
92 	HVSI_WAIT_FOR_VER_QUERY,
93 	HVSI_OPEN,
94 	HVSI_WAIT_FOR_MCTRL_RESPONSE,
95 	HVSI_FSP_DIED,
96 };
97 #define HVSI_CONSOLE 0x1
98 
is_console(struct hvsi_struct * hp)99 static inline int is_console(struct hvsi_struct *hp)
100 {
101 	return hp->flags & HVSI_CONSOLE;
102 }
103 
is_open(struct hvsi_struct * hp)104 static inline int is_open(struct hvsi_struct *hp)
105 {
106 	/* if we're waiting for an mctrl then we're already open */
107 	return (hp->state == HVSI_OPEN)
108 			|| (hp->state == HVSI_WAIT_FOR_MCTRL_RESPONSE);
109 }
110 
print_state(struct hvsi_struct * hp)111 static inline void print_state(struct hvsi_struct *hp)
112 {
113 #ifdef DEBUG
114 	static const char *state_names[] = {
115 		"HVSI_CLOSED",
116 		"HVSI_WAIT_FOR_VER_RESPONSE",
117 		"HVSI_WAIT_FOR_VER_QUERY",
118 		"HVSI_OPEN",
119 		"HVSI_WAIT_FOR_MCTRL_RESPONSE",
120 		"HVSI_FSP_DIED",
121 	};
122 	const char *name = (hp->state < ARRAY_SIZE(state_names))
123 		? state_names[hp->state] : "UNKNOWN";
124 
125 	pr_debug("hvsi%i: state = %s\n", hp->index, name);
126 #endif /* DEBUG */
127 }
128 
__set_state(struct hvsi_struct * hp,int state)129 static inline void __set_state(struct hvsi_struct *hp, int state)
130 {
131 	hp->state = state;
132 	print_state(hp);
133 	wake_up_all(&hp->stateq);
134 }
135 
set_state(struct hvsi_struct * hp,int state)136 static inline void set_state(struct hvsi_struct *hp, int state)
137 {
138 	unsigned long flags;
139 
140 	spin_lock_irqsave(&hp->lock, flags);
141 	__set_state(hp, state);
142 	spin_unlock_irqrestore(&hp->lock, flags);
143 }
144 
len_packet(const uint8_t * packet)145 static inline int len_packet(const uint8_t *packet)
146 {
147 	return (int)((struct hvsi_header *)packet)->len;
148 }
149 
is_header(const uint8_t * packet)150 static inline int is_header(const uint8_t *packet)
151 {
152 	struct hvsi_header *header = (struct hvsi_header *)packet;
153 	return header->type >= VS_QUERY_RESPONSE_PACKET_HEADER;
154 }
155 
got_packet(const struct hvsi_struct * hp,uint8_t * packet)156 static inline int got_packet(const struct hvsi_struct *hp, uint8_t *packet)
157 {
158 	if (hp->inbuf_end < packet + sizeof(struct hvsi_header))
159 		return 0; /* don't even have the packet header */
160 
161 	if (hp->inbuf_end < (packet + len_packet(packet)))
162 		return 0; /* don't have the rest of the packet */
163 
164 	return 1;
165 }
166 
167 /* shift remaining bytes in packetbuf down */
compact_inbuf(struct hvsi_struct * hp,uint8_t * read_to)168 static void compact_inbuf(struct hvsi_struct *hp, uint8_t *read_to)
169 {
170 	int remaining = (int)(hp->inbuf_end - read_to);
171 
172 	pr_debug("%s: %i chars remain\n", __func__, remaining);
173 
174 	if (read_to != hp->inbuf)
175 		memmove(hp->inbuf, read_to, remaining);
176 
177 	hp->inbuf_end = hp->inbuf + remaining;
178 }
179 
180 #ifdef DEBUG
181 #define dbg_dump_packet(packet) dump_packet(packet)
182 #define dbg_dump_hex(data, len) dump_hex(data, len)
183 #else
184 #define dbg_dump_packet(packet) do { } while (0)
185 #define dbg_dump_hex(data, len) do { } while (0)
186 #endif
187 
dump_hex(const uint8_t * data,int len)188 static void dump_hex(const uint8_t *data, int len)
189 {
190 	int i;
191 
192 	printk("    ");
193 	for (i=0; i < len; i++)
194 		printk("%.2x", data[i]);
195 
196 	printk("\n    ");
197 	for (i=0; i < len; i++) {
198 		if (isprint(data[i]))
199 			printk("%c", data[i]);
200 		else
201 			printk(".");
202 	}
203 	printk("\n");
204 }
205 
dump_packet(uint8_t * packet)206 static void dump_packet(uint8_t *packet)
207 {
208 	struct hvsi_header *header = (struct hvsi_header *)packet;
209 
210 	printk("type 0x%x, len %i, seqno %i:\n", header->type, header->len,
211 			header->seqno);
212 
213 	dump_hex(packet, header->len);
214 }
215 
hvsi_read(struct hvsi_struct * hp,char * buf,int count)216 static int hvsi_read(struct hvsi_struct *hp, char *buf, int count)
217 {
218 	unsigned long got;
219 
220 	got = hvc_get_chars(hp->vtermno, buf, count);
221 
222 	return got;
223 }
224 
hvsi_recv_control(struct hvsi_struct * hp,uint8_t * packet,struct tty_struct * tty,struct hvsi_struct ** to_handshake)225 static void hvsi_recv_control(struct hvsi_struct *hp, uint8_t *packet,
226 	struct tty_struct *tty, struct hvsi_struct **to_handshake)
227 {
228 	struct hvsi_control *header = (struct hvsi_control *)packet;
229 
230 	switch (be16_to_cpu(header->verb)) {
231 		case VSV_MODEM_CTL_UPDATE:
232 			if ((be32_to_cpu(header->word) & HVSI_TSCD) == 0) {
233 				/* CD went away; no more connection */
234 				pr_debug("hvsi%i: CD dropped\n", hp->index);
235 				hp->mctrl &= TIOCM_CD;
236 				if (tty && !C_CLOCAL(tty))
237 					tty_hangup(tty);
238 			}
239 			break;
240 		case VSV_CLOSE_PROTOCOL:
241 			pr_debug("hvsi%i: service processor came back\n", hp->index);
242 			if (hp->state != HVSI_CLOSED) {
243 				*to_handshake = hp;
244 			}
245 			break;
246 		default:
247 			printk(KERN_WARNING "hvsi%i: unknown HVSI control packet: ",
248 				hp->index);
249 			dump_packet(packet);
250 			break;
251 	}
252 }
253 
hvsi_recv_response(struct hvsi_struct * hp,uint8_t * packet)254 static void hvsi_recv_response(struct hvsi_struct *hp, uint8_t *packet)
255 {
256 	struct hvsi_query_response *resp = (struct hvsi_query_response *)packet;
257 	uint32_t mctrl_word;
258 
259 	switch (hp->state) {
260 		case HVSI_WAIT_FOR_VER_RESPONSE:
261 			__set_state(hp, HVSI_WAIT_FOR_VER_QUERY);
262 			break;
263 		case HVSI_WAIT_FOR_MCTRL_RESPONSE:
264 			hp->mctrl = 0;
265 			mctrl_word = be32_to_cpu(resp->u.mctrl_word);
266 			if (mctrl_word & HVSI_TSDTR)
267 				hp->mctrl |= TIOCM_DTR;
268 			if (mctrl_word & HVSI_TSCD)
269 				hp->mctrl |= TIOCM_CD;
270 			__set_state(hp, HVSI_OPEN);
271 			break;
272 		default:
273 			printk(KERN_ERR "hvsi%i: unexpected query response: ", hp->index);
274 			dump_packet(packet);
275 			break;
276 	}
277 }
278 
279 /* respond to service processor's version query */
hvsi_version_respond(struct hvsi_struct * hp,uint16_t query_seqno)280 static int hvsi_version_respond(struct hvsi_struct *hp, uint16_t query_seqno)
281 {
282 	struct hvsi_query_response packet __ALIGNED__;
283 	int wrote;
284 
285 	packet.hdr.type = VS_QUERY_RESPONSE_PACKET_HEADER;
286 	packet.hdr.len = sizeof(struct hvsi_query_response);
287 	packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
288 	packet.verb = cpu_to_be16(VSV_SEND_VERSION_NUMBER);
289 	packet.u.version = HVSI_VERSION;
290 	packet.query_seqno = cpu_to_be16(query_seqno+1);
291 
292 	pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
293 	dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
294 
295 	wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
296 	if (wrote != packet.hdr.len) {
297 		printk(KERN_ERR "hvsi%i: couldn't send query response!\n",
298 			hp->index);
299 		return -EIO;
300 	}
301 
302 	return 0;
303 }
304 
hvsi_recv_query(struct hvsi_struct * hp,uint8_t * packet)305 static void hvsi_recv_query(struct hvsi_struct *hp, uint8_t *packet)
306 {
307 	struct hvsi_query *query = (struct hvsi_query *)packet;
308 
309 	switch (hp->state) {
310 		case HVSI_WAIT_FOR_VER_QUERY:
311 			hvsi_version_respond(hp, be16_to_cpu(query->hdr.seqno));
312 			__set_state(hp, HVSI_OPEN);
313 			break;
314 		default:
315 			printk(KERN_ERR "hvsi%i: unexpected query: ", hp->index);
316 			dump_packet(packet);
317 			break;
318 	}
319 }
320 
hvsi_insert_chars(struct hvsi_struct * hp,const char * buf,int len)321 static void hvsi_insert_chars(struct hvsi_struct *hp, const char *buf, int len)
322 {
323 	int i;
324 
325 	for (i=0; i < len; i++) {
326 		char c = buf[i];
327 #ifdef CONFIG_MAGIC_SYSRQ
328 		if (c == '\0') {
329 			hp->sysrq = 1;
330 			continue;
331 		} else if (hp->sysrq) {
332 			handle_sysrq(c);
333 			hp->sysrq = 0;
334 			continue;
335 		}
336 #endif /* CONFIG_MAGIC_SYSRQ */
337 		tty_insert_flip_char(&hp->port, c, 0);
338 	}
339 }
340 
341 /*
342  * We could get 252 bytes of data at once here. But the tty layer only
343  * throttles us at TTY_THRESHOLD_THROTTLE (128) bytes, so we could overflow
344  * it. Accordingly we won't send more than 128 bytes at a time to the flip
345  * buffer, which will give the tty buffer a chance to throttle us. Should the
346  * value of TTY_THRESHOLD_THROTTLE change in n_tty.c, this code should be
347  * revisited.
348  */
349 #define TTY_THRESHOLD_THROTTLE 128
hvsi_recv_data(struct hvsi_struct * hp,const uint8_t * packet)350 static bool hvsi_recv_data(struct hvsi_struct *hp, const uint8_t *packet)
351 {
352 	const struct hvsi_header *header = (const struct hvsi_header *)packet;
353 	const uint8_t *data = packet + sizeof(struct hvsi_header);
354 	int datalen = header->len - sizeof(struct hvsi_header);
355 	int overflow = datalen - TTY_THRESHOLD_THROTTLE;
356 
357 	pr_debug("queueing %i chars '%.*s'\n", datalen, datalen, data);
358 
359 	if (datalen == 0)
360 		return false;
361 
362 	if (overflow > 0) {
363 		pr_debug("%s: got >TTY_THRESHOLD_THROTTLE bytes\n", __func__);
364 		datalen = TTY_THRESHOLD_THROTTLE;
365 	}
366 
367 	hvsi_insert_chars(hp, data, datalen);
368 
369 	if (overflow > 0) {
370 		/*
371 		 * we still have more data to deliver, so we need to save off the
372 		 * overflow and send it later
373 		 */
374 		pr_debug("%s: deferring overflow\n", __func__);
375 		memcpy(hp->throttle_buf, data + TTY_THRESHOLD_THROTTLE, overflow);
376 		hp->n_throttle = overflow;
377 	}
378 
379 	return true;
380 }
381 
382 /*
383  * Returns true/false indicating data successfully read from hypervisor.
384  * Used both to get packets for tty connections and to advance the state
385  * machine during console handshaking (in which case tty = NULL and we ignore
386  * incoming data).
387  */
hvsi_load_chunk(struct hvsi_struct * hp,struct tty_struct * tty,struct hvsi_struct ** handshake)388 static int hvsi_load_chunk(struct hvsi_struct *hp, struct tty_struct *tty,
389 		struct hvsi_struct **handshake)
390 {
391 	uint8_t *packet = hp->inbuf;
392 	int chunklen;
393 	bool flip = false;
394 
395 	*handshake = NULL;
396 
397 	chunklen = hvsi_read(hp, hp->inbuf_end, HVSI_MAX_READ);
398 	if (chunklen == 0) {
399 		pr_debug("%s: 0-length read\n", __func__);
400 		return 0;
401 	}
402 
403 	pr_debug("%s: got %i bytes\n", __func__, chunklen);
404 	dbg_dump_hex(hp->inbuf_end, chunklen);
405 
406 	hp->inbuf_end += chunklen;
407 
408 	/* handle all completed packets */
409 	while ((packet < hp->inbuf_end) && got_packet(hp, packet)) {
410 		struct hvsi_header *header = (struct hvsi_header *)packet;
411 
412 		if (!is_header(packet)) {
413 			printk(KERN_ERR "hvsi%i: got malformed packet\n", hp->index);
414 			/* skip bytes until we find a header or run out of data */
415 			while ((packet < hp->inbuf_end) && (!is_header(packet)))
416 				packet++;
417 			continue;
418 		}
419 
420 		pr_debug("%s: handling %i-byte packet\n", __func__,
421 				len_packet(packet));
422 		dbg_dump_packet(packet);
423 
424 		switch (header->type) {
425 			case VS_DATA_PACKET_HEADER:
426 				if (!is_open(hp))
427 					break;
428 				flip = hvsi_recv_data(hp, packet);
429 				break;
430 			case VS_CONTROL_PACKET_HEADER:
431 				hvsi_recv_control(hp, packet, tty, handshake);
432 				break;
433 			case VS_QUERY_RESPONSE_PACKET_HEADER:
434 				hvsi_recv_response(hp, packet);
435 				break;
436 			case VS_QUERY_PACKET_HEADER:
437 				hvsi_recv_query(hp, packet);
438 				break;
439 			default:
440 				printk(KERN_ERR "hvsi%i: unknown HVSI packet type 0x%x\n",
441 						hp->index, header->type);
442 				dump_packet(packet);
443 				break;
444 		}
445 
446 		packet += len_packet(packet);
447 
448 		if (*handshake) {
449 			pr_debug("%s: handshake\n", __func__);
450 			break;
451 		}
452 	}
453 
454 	compact_inbuf(hp, packet);
455 
456 	if (flip)
457 		tty_flip_buffer_push(&hp->port);
458 
459 	return 1;
460 }
461 
hvsi_send_overflow(struct hvsi_struct * hp)462 static void hvsi_send_overflow(struct hvsi_struct *hp)
463 {
464 	pr_debug("%s: delivering %i bytes overflow\n", __func__,
465 			hp->n_throttle);
466 
467 	hvsi_insert_chars(hp, hp->throttle_buf, hp->n_throttle);
468 	hp->n_throttle = 0;
469 }
470 
471 /*
472  * must get all pending data because we only get an irq on empty->non-empty
473  * transition
474  */
hvsi_interrupt(int irq,void * arg)475 static irqreturn_t hvsi_interrupt(int irq, void *arg)
476 {
477 	struct hvsi_struct *hp = (struct hvsi_struct *)arg;
478 	struct hvsi_struct *handshake;
479 	struct tty_struct *tty;
480 	unsigned long flags;
481 	int again = 1;
482 
483 	pr_debug("%s\n", __func__);
484 
485 	tty = tty_port_tty_get(&hp->port);
486 
487 	while (again) {
488 		spin_lock_irqsave(&hp->lock, flags);
489 		again = hvsi_load_chunk(hp, tty, &handshake);
490 		spin_unlock_irqrestore(&hp->lock, flags);
491 
492 		if (handshake) {
493 			pr_debug("hvsi%i: attempting re-handshake\n", handshake->index);
494 			schedule_work(&handshake->handshaker);
495 		}
496 	}
497 
498 	spin_lock_irqsave(&hp->lock, flags);
499 	if (tty && hp->n_throttle && !tty_throttled(tty)) {
500 		/* we weren't hung up and we weren't throttled, so we can
501 		 * deliver the rest now */
502 		hvsi_send_overflow(hp);
503 		tty_flip_buffer_push(&hp->port);
504 	}
505 	spin_unlock_irqrestore(&hp->lock, flags);
506 
507 	tty_kref_put(tty);
508 
509 	return IRQ_HANDLED;
510 }
511 
512 /* for boot console, before the irq handler is running */
poll_for_state(struct hvsi_struct * hp,int state)513 static int __init poll_for_state(struct hvsi_struct *hp, int state)
514 {
515 	unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;
516 
517 	for (;;) {
518 		hvsi_interrupt(hp->virq, (void *)hp); /* get pending data */
519 
520 		if (hp->state == state)
521 			return 0;
522 
523 		mdelay(5);
524 		if (time_after(jiffies, end_jiffies))
525 			return -EIO;
526 	}
527 }
528 
529 /* wait for irq handler to change our state */
wait_for_state(struct hvsi_struct * hp,int state)530 static int wait_for_state(struct hvsi_struct *hp, int state)
531 {
532 	int ret = 0;
533 
534 	if (!wait_event_timeout(hp->stateq, (hp->state == state), HVSI_TIMEOUT))
535 		ret = -EIO;
536 
537 	return ret;
538 }
539 
hvsi_query(struct hvsi_struct * hp,uint16_t verb)540 static int hvsi_query(struct hvsi_struct *hp, uint16_t verb)
541 {
542 	struct hvsi_query packet __ALIGNED__;
543 	int wrote;
544 
545 	packet.hdr.type = VS_QUERY_PACKET_HEADER;
546 	packet.hdr.len = sizeof(struct hvsi_query);
547 	packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
548 	packet.verb = cpu_to_be16(verb);
549 
550 	pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
551 	dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
552 
553 	wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
554 	if (wrote != packet.hdr.len) {
555 		printk(KERN_ERR "hvsi%i: couldn't send query (%i)!\n", hp->index,
556 			wrote);
557 		return -EIO;
558 	}
559 
560 	return 0;
561 }
562 
hvsi_get_mctrl(struct hvsi_struct * hp)563 static int hvsi_get_mctrl(struct hvsi_struct *hp)
564 {
565 	int ret;
566 
567 	set_state(hp, HVSI_WAIT_FOR_MCTRL_RESPONSE);
568 	hvsi_query(hp, VSV_SEND_MODEM_CTL_STATUS);
569 
570 	ret = hvsi_wait(hp, HVSI_OPEN);
571 	if (ret < 0) {
572 		printk(KERN_ERR "hvsi%i: didn't get modem flags\n", hp->index);
573 		set_state(hp, HVSI_OPEN);
574 		return ret;
575 	}
576 
577 	pr_debug("%s: mctrl 0x%x\n", __func__, hp->mctrl);
578 
579 	return 0;
580 }
581 
582 /* note that we can only set DTR */
hvsi_set_mctrl(struct hvsi_struct * hp,uint16_t mctrl)583 static int hvsi_set_mctrl(struct hvsi_struct *hp, uint16_t mctrl)
584 {
585 	struct hvsi_control packet __ALIGNED__;
586 	int wrote;
587 
588 	packet.hdr.type = VS_CONTROL_PACKET_HEADER;
589 	packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
590 	packet.hdr.len = sizeof(struct hvsi_control);
591 	packet.verb = cpu_to_be16(VSV_SET_MODEM_CTL);
592 	packet.mask = cpu_to_be32(HVSI_TSDTR);
593 
594 	if (mctrl & TIOCM_DTR)
595 		packet.word = cpu_to_be32(HVSI_TSDTR);
596 
597 	pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
598 	dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
599 
600 	wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
601 	if (wrote != packet.hdr.len) {
602 		printk(KERN_ERR "hvsi%i: couldn't set DTR!\n", hp->index);
603 		return -EIO;
604 	}
605 
606 	return 0;
607 }
608 
hvsi_drain_input(struct hvsi_struct * hp)609 static void hvsi_drain_input(struct hvsi_struct *hp)
610 {
611 	uint8_t buf[HVSI_MAX_READ] __ALIGNED__;
612 	unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;
613 
614 	while (time_before(end_jiffies, jiffies))
615 		if (0 == hvsi_read(hp, buf, HVSI_MAX_READ))
616 			break;
617 }
618 
hvsi_handshake(struct hvsi_struct * hp)619 static int hvsi_handshake(struct hvsi_struct *hp)
620 {
621 	int ret;
622 
623 	/*
624 	 * We could have a CLOSE or other data waiting for us before we even try
625 	 * to open; try to throw it all away so we don't get confused. (CLOSE
626 	 * is the first message sent up the pipe when the FSP comes online. We
627 	 * need to distinguish between "it came up a while ago and we're the first
628 	 * user" and "it was just reset before it saw our handshake packet".)
629 	 */
630 	hvsi_drain_input(hp);
631 
632 	set_state(hp, HVSI_WAIT_FOR_VER_RESPONSE);
633 	ret = hvsi_query(hp, VSV_SEND_VERSION_NUMBER);
634 	if (ret < 0) {
635 		printk(KERN_ERR "hvsi%i: couldn't send version query\n", hp->index);
636 		return ret;
637 	}
638 
639 	ret = hvsi_wait(hp, HVSI_OPEN);
640 	if (ret < 0)
641 		return ret;
642 
643 	return 0;
644 }
645 
hvsi_handshaker(struct work_struct * work)646 static void hvsi_handshaker(struct work_struct *work)
647 {
648 	struct hvsi_struct *hp =
649 		container_of(work, struct hvsi_struct, handshaker);
650 
651 	if (hvsi_handshake(hp) >= 0)
652 		return;
653 
654 	printk(KERN_ERR "hvsi%i: re-handshaking failed\n", hp->index);
655 	if (is_console(hp)) {
656 		/*
657 		 * ttys will re-attempt the handshake via hvsi_open, but
658 		 * the console will not.
659 		 */
660 		printk(KERN_ERR "hvsi%i: lost console!\n", hp->index);
661 	}
662 }
663 
hvsi_put_chars(struct hvsi_struct * hp,const char * buf,int count)664 static int hvsi_put_chars(struct hvsi_struct *hp, const char *buf, int count)
665 {
666 	struct hvsi_data packet __ALIGNED__;
667 	int ret;
668 
669 	BUG_ON(count > HVSI_MAX_OUTGOING_DATA);
670 
671 	packet.hdr.type = VS_DATA_PACKET_HEADER;
672 	packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
673 	packet.hdr.len = count + sizeof(struct hvsi_header);
674 	memcpy(&packet.data, buf, count);
675 
676 	ret = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
677 	if (ret == packet.hdr.len) {
678 		/* return the number of chars written, not the packet length */
679 		return count;
680 	}
681 	return ret; /* return any errors */
682 }
683 
hvsi_close_protocol(struct hvsi_struct * hp)684 static void hvsi_close_protocol(struct hvsi_struct *hp)
685 {
686 	struct hvsi_control packet __ALIGNED__;
687 
688 	packet.hdr.type = VS_CONTROL_PACKET_HEADER;
689 	packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
690 	packet.hdr.len = 6;
691 	packet.verb = cpu_to_be16(VSV_CLOSE_PROTOCOL);
692 
693 	pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
694 	dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
695 
696 	hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
697 }
698 
hvsi_open(struct tty_struct * tty,struct file * filp)699 static int hvsi_open(struct tty_struct *tty, struct file *filp)
700 {
701 	struct hvsi_struct *hp;
702 	unsigned long flags;
703 	int ret;
704 
705 	pr_debug("%s\n", __func__);
706 
707 	hp = &hvsi_ports[tty->index];
708 
709 	tty->driver_data = hp;
710 
711 	mb();
712 	if (hp->state == HVSI_FSP_DIED)
713 		return -EIO;
714 
715 	tty_port_tty_set(&hp->port, tty);
716 	spin_lock_irqsave(&hp->lock, flags);
717 	hp->port.count++;
718 	atomic_set(&hp->seqno, 0);
719 	h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
720 	spin_unlock_irqrestore(&hp->lock, flags);
721 
722 	if (is_console(hp))
723 		return 0; /* this has already been handshaked as the console */
724 
725 	ret = hvsi_handshake(hp);
726 	if (ret < 0) {
727 		printk(KERN_ERR "%s: HVSI handshaking failed\n", tty->name);
728 		return ret;
729 	}
730 
731 	ret = hvsi_get_mctrl(hp);
732 	if (ret < 0) {
733 		printk(KERN_ERR "%s: couldn't get initial modem flags\n", tty->name);
734 		return ret;
735 	}
736 
737 	ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
738 	if (ret < 0) {
739 		printk(KERN_ERR "%s: couldn't set DTR\n", tty->name);
740 		return ret;
741 	}
742 
743 	return 0;
744 }
745 
746 /* wait for hvsi_write_worker to empty hp->outbuf */
hvsi_flush_output(struct hvsi_struct * hp)747 static void hvsi_flush_output(struct hvsi_struct *hp)
748 {
749 	wait_event_timeout(hp->emptyq, (hp->n_outbuf <= 0), HVSI_TIMEOUT);
750 
751 	/* 'writer' could still be pending if it didn't see n_outbuf = 0 yet */
752 	cancel_delayed_work_sync(&hp->writer);
753 	flush_work(&hp->handshaker);
754 
755 	/*
756 	 * it's also possible that our timeout expired and hvsi_write_worker
757 	 * didn't manage to push outbuf. poof.
758 	 */
759 	hp->n_outbuf = 0;
760 }
761 
hvsi_close(struct tty_struct * tty,struct file * filp)762 static void hvsi_close(struct tty_struct *tty, struct file *filp)
763 {
764 	struct hvsi_struct *hp = tty->driver_data;
765 	unsigned long flags;
766 
767 	pr_debug("%s\n", __func__);
768 
769 	if (tty_hung_up_p(filp))
770 		return;
771 
772 	spin_lock_irqsave(&hp->lock, flags);
773 
774 	if (--hp->port.count == 0) {
775 		tty_port_tty_set(&hp->port, NULL);
776 		hp->inbuf_end = hp->inbuf; /* discard remaining partial packets */
777 
778 		/* only close down connection if it is not the console */
779 		if (!is_console(hp)) {
780 			h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE); /* no more irqs */
781 			__set_state(hp, HVSI_CLOSED);
782 			/*
783 			 * any data delivered to the tty layer after this will be
784 			 * discarded (except for XON/XOFF)
785 			 */
786 			tty->closing = 1;
787 
788 			spin_unlock_irqrestore(&hp->lock, flags);
789 
790 			/* let any existing irq handlers finish. no more will start. */
791 			synchronize_irq(hp->virq);
792 
793 			/* hvsi_write_worker will re-schedule until outbuf is empty. */
794 			hvsi_flush_output(hp);
795 
796 			/* tell FSP to stop sending data */
797 			hvsi_close_protocol(hp);
798 
799 			/*
800 			 * drain anything FSP is still in the middle of sending, and let
801 			 * hvsi_handshake drain the rest on the next open.
802 			 */
803 			hvsi_drain_input(hp);
804 
805 			spin_lock_irqsave(&hp->lock, flags);
806 		}
807 	} else if (hp->port.count < 0)
808 		printk(KERN_ERR "hvsi_close %lu: oops, count is %d\n",
809 		       hp - hvsi_ports, hp->port.count);
810 
811 	spin_unlock_irqrestore(&hp->lock, flags);
812 }
813 
hvsi_hangup(struct tty_struct * tty)814 static void hvsi_hangup(struct tty_struct *tty)
815 {
816 	struct hvsi_struct *hp = tty->driver_data;
817 	unsigned long flags;
818 
819 	pr_debug("%s\n", __func__);
820 
821 	tty_port_tty_set(&hp->port, NULL);
822 
823 	spin_lock_irqsave(&hp->lock, flags);
824 	hp->port.count = 0;
825 	hp->n_outbuf = 0;
826 	spin_unlock_irqrestore(&hp->lock, flags);
827 }
828 
829 /* called with hp->lock held */
hvsi_push(struct hvsi_struct * hp)830 static void hvsi_push(struct hvsi_struct *hp)
831 {
832 	int n;
833 
834 	if (hp->n_outbuf <= 0)
835 		return;
836 
837 	n = hvsi_put_chars(hp, hp->outbuf, hp->n_outbuf);
838 	if (n > 0) {
839 		/* success */
840 		pr_debug("%s: wrote %i chars\n", __func__, n);
841 		hp->n_outbuf = 0;
842 	} else if (n == -EIO) {
843 		__set_state(hp, HVSI_FSP_DIED);
844 		printk(KERN_ERR "hvsi%i: service processor died\n", hp->index);
845 	}
846 }
847 
848 /* hvsi_write_worker will keep rescheduling itself until outbuf is empty */
hvsi_write_worker(struct work_struct * work)849 static void hvsi_write_worker(struct work_struct *work)
850 {
851 	struct hvsi_struct *hp =
852 		container_of(work, struct hvsi_struct, writer.work);
853 	unsigned long flags;
854 #ifdef DEBUG
855 	static long start_j = 0;
856 
857 	if (start_j == 0)
858 		start_j = jiffies;
859 #endif /* DEBUG */
860 
861 	spin_lock_irqsave(&hp->lock, flags);
862 
863 	pr_debug("%s: %i chars in buffer\n", __func__, hp->n_outbuf);
864 
865 	if (!is_open(hp)) {
866 		/*
867 		 * We could have a non-open connection if the service processor died
868 		 * while we were busily scheduling ourselves. In that case, it could
869 		 * be minutes before the service processor comes back, so only try
870 		 * again once a second.
871 		 */
872 		schedule_delayed_work(&hp->writer, HZ);
873 		goto out;
874 	}
875 
876 	hvsi_push(hp);
877 	if (hp->n_outbuf > 0)
878 		schedule_delayed_work(&hp->writer, 10);
879 	else {
880 #ifdef DEBUG
881 		pr_debug("%s: outbuf emptied after %li jiffies\n", __func__,
882 				jiffies - start_j);
883 		start_j = 0;
884 #endif /* DEBUG */
885 		wake_up_all(&hp->emptyq);
886 		tty_port_tty_wakeup(&hp->port);
887 	}
888 
889 out:
890 	spin_unlock_irqrestore(&hp->lock, flags);
891 }
892 
hvsi_write_room(struct tty_struct * tty)893 static unsigned int hvsi_write_room(struct tty_struct *tty)
894 {
895 	struct hvsi_struct *hp = tty->driver_data;
896 
897 	return N_OUTBUF - hp->n_outbuf;
898 }
899 
hvsi_chars_in_buffer(struct tty_struct * tty)900 static unsigned int hvsi_chars_in_buffer(struct tty_struct *tty)
901 {
902 	struct hvsi_struct *hp = tty->driver_data;
903 
904 	return hp->n_outbuf;
905 }
906 
hvsi_write(struct tty_struct * tty,const u8 * source,size_t count)907 static ssize_t hvsi_write(struct tty_struct *tty, const u8 *source,
908 			  size_t count)
909 {
910 	struct hvsi_struct *hp = tty->driver_data;
911 	unsigned long flags;
912 	size_t total = 0;
913 	size_t origcount = count;
914 
915 	spin_lock_irqsave(&hp->lock, flags);
916 
917 	pr_debug("%s: %i chars in buffer\n", __func__, hp->n_outbuf);
918 
919 	if (!is_open(hp)) {
920 		/* we're either closing or not yet open; don't accept data */
921 		pr_debug("%s: not open\n", __func__);
922 		goto out;
923 	}
924 
925 	/*
926 	 * when the hypervisor buffer (16K) fills, data will stay in hp->outbuf
927 	 * and hvsi_write_worker will be scheduled. subsequent hvsi_write() calls
928 	 * will see there is no room in outbuf and return.
929 	 */
930 	while ((count > 0) && (hvsi_write_room(tty) > 0)) {
931 		size_t chunksize = min_t(size_t, count, hvsi_write_room(tty));
932 
933 		BUG_ON(hp->n_outbuf < 0);
934 		memcpy(hp->outbuf + hp->n_outbuf, source, chunksize);
935 		hp->n_outbuf += chunksize;
936 
937 		total += chunksize;
938 		source += chunksize;
939 		count -= chunksize;
940 		hvsi_push(hp);
941 	}
942 
943 	if (hp->n_outbuf > 0) {
944 		/*
945 		 * we weren't able to write it all to the hypervisor.
946 		 * schedule another push attempt.
947 		 */
948 		schedule_delayed_work(&hp->writer, 10);
949 	}
950 
951 out:
952 	spin_unlock_irqrestore(&hp->lock, flags);
953 
954 	if (total != origcount)
955 		pr_debug("%s: wanted %zu, only wrote %zu\n", __func__,
956 			 origcount, total);
957 
958 	return total;
959 }
960 
961 /*
962  * I have never seen throttle or unthrottle called, so this little throttle
963  * buffering scheme may or may not work.
964  */
hvsi_throttle(struct tty_struct * tty)965 static void hvsi_throttle(struct tty_struct *tty)
966 {
967 	struct hvsi_struct *hp = tty->driver_data;
968 
969 	pr_debug("%s\n", __func__);
970 
971 	h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE);
972 }
973 
hvsi_unthrottle(struct tty_struct * tty)974 static void hvsi_unthrottle(struct tty_struct *tty)
975 {
976 	struct hvsi_struct *hp = tty->driver_data;
977 	unsigned long flags;
978 
979 	pr_debug("%s\n", __func__);
980 
981 	spin_lock_irqsave(&hp->lock, flags);
982 	if (hp->n_throttle) {
983 		hvsi_send_overflow(hp);
984 		tty_flip_buffer_push(&hp->port);
985 	}
986 	spin_unlock_irqrestore(&hp->lock, flags);
987 
988 
989 	h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
990 }
991 
hvsi_tiocmget(struct tty_struct * tty)992 static int hvsi_tiocmget(struct tty_struct *tty)
993 {
994 	struct hvsi_struct *hp = tty->driver_data;
995 
996 	hvsi_get_mctrl(hp);
997 	return hp->mctrl;
998 }
999 
hvsi_tiocmset(struct tty_struct * tty,unsigned int set,unsigned int clear)1000 static int hvsi_tiocmset(struct tty_struct *tty,
1001 				unsigned int set, unsigned int clear)
1002 {
1003 	struct hvsi_struct *hp = tty->driver_data;
1004 	unsigned long flags;
1005 	uint16_t new_mctrl;
1006 
1007 	/* we can only alter DTR */
1008 	clear &= TIOCM_DTR;
1009 	set &= TIOCM_DTR;
1010 
1011 	spin_lock_irqsave(&hp->lock, flags);
1012 
1013 	new_mctrl = (hp->mctrl & ~clear) | set;
1014 
1015 	if (hp->mctrl != new_mctrl) {
1016 		hvsi_set_mctrl(hp, new_mctrl);
1017 		hp->mctrl = new_mctrl;
1018 	}
1019 	spin_unlock_irqrestore(&hp->lock, flags);
1020 
1021 	return 0;
1022 }
1023 
1024 
1025 static const struct tty_operations hvsi_ops = {
1026 	.open = hvsi_open,
1027 	.close = hvsi_close,
1028 	.write = hvsi_write,
1029 	.hangup = hvsi_hangup,
1030 	.write_room = hvsi_write_room,
1031 	.chars_in_buffer = hvsi_chars_in_buffer,
1032 	.throttle = hvsi_throttle,
1033 	.unthrottle = hvsi_unthrottle,
1034 	.tiocmget = hvsi_tiocmget,
1035 	.tiocmset = hvsi_tiocmset,
1036 };
1037 
hvsi_init(void)1038 static int __init hvsi_init(void)
1039 {
1040 	struct tty_driver *driver;
1041 	int i, ret;
1042 
1043 	driver = tty_alloc_driver(hvsi_count, TTY_DRIVER_REAL_RAW);
1044 	if (IS_ERR(driver))
1045 		return PTR_ERR(driver);
1046 
1047 	driver->driver_name = "hvsi";
1048 	driver->name = "hvsi";
1049 	driver->major = HVSI_MAJOR;
1050 	driver->minor_start = HVSI_MINOR;
1051 	driver->type = TTY_DRIVER_TYPE_SYSTEM;
1052 	driver->init_termios = tty_std_termios;
1053 	driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL;
1054 	driver->init_termios.c_ispeed = 9600;
1055 	driver->init_termios.c_ospeed = 9600;
1056 	tty_set_operations(driver, &hvsi_ops);
1057 
1058 	for (i=0; i < hvsi_count; i++) {
1059 		struct hvsi_struct *hp = &hvsi_ports[i];
1060 		int ret = 1;
1061 
1062 		tty_port_link_device(&hp->port, driver, i);
1063 
1064 		ret = request_irq(hp->virq, hvsi_interrupt, 0, "hvsi", hp);
1065 		if (ret)
1066 			printk(KERN_ERR "HVSI: couldn't reserve irq 0x%x (error %i)\n",
1067 				hp->virq, ret);
1068 	}
1069 	hvsi_wait = wait_for_state; /* irqs active now */
1070 
1071 	ret = tty_register_driver(driver);
1072 	if (ret) {
1073 		pr_err("Couldn't register hvsi console driver\n");
1074 		goto err_free_irq;
1075 	}
1076 
1077 	hvsi_driver = driver;
1078 
1079 	printk(KERN_DEBUG "HVSI: registered %i devices\n", hvsi_count);
1080 
1081 	return 0;
1082 err_free_irq:
1083 	hvsi_wait = poll_for_state;
1084 	for (i = 0; i < hvsi_count; i++) {
1085 		struct hvsi_struct *hp = &hvsi_ports[i];
1086 
1087 		free_irq(hp->virq, hp);
1088 	}
1089 	tty_driver_kref_put(driver);
1090 
1091 	return ret;
1092 }
1093 device_initcall(hvsi_init);
1094 
1095 /***** console (not tty) code: *****/
1096 
hvsi_console_print(struct console * console,const char * buf,unsigned int count)1097 static void hvsi_console_print(struct console *console, const char *buf,
1098 		unsigned int count)
1099 {
1100 	struct hvsi_struct *hp = &hvsi_ports[console->index];
1101 	char c[HVSI_MAX_OUTGOING_DATA] __ALIGNED__;
1102 	unsigned int i = 0, n = 0;
1103 	int ret, donecr = 0;
1104 
1105 	mb();
1106 	if (!is_open(hp))
1107 		return;
1108 
1109 	/*
1110 	 * ugh, we have to translate LF -> CRLF ourselves, in place.
1111 	 * copied from hvc_console.c:
1112 	 */
1113 	while (count > 0 || i > 0) {
1114 		if (count > 0 && i < sizeof(c)) {
1115 			if (buf[n] == '\n' && !donecr) {
1116 				c[i++] = '\r';
1117 				donecr = 1;
1118 			} else {
1119 				c[i++] = buf[n++];
1120 				donecr = 0;
1121 				--count;
1122 			}
1123 		} else {
1124 			ret = hvsi_put_chars(hp, c, i);
1125 			if (ret < 0)
1126 				i = 0;
1127 			i -= ret;
1128 		}
1129 	}
1130 }
1131 
hvsi_console_device(struct console * console,int * index)1132 static struct tty_driver *hvsi_console_device(struct console *console,
1133 	int *index)
1134 {
1135 	*index = console->index;
1136 	return hvsi_driver;
1137 }
1138 
hvsi_console_setup(struct console * console,char * options)1139 static int __init hvsi_console_setup(struct console *console, char *options)
1140 {
1141 	struct hvsi_struct *hp;
1142 	int ret;
1143 
1144 	if (console->index < 0 || console->index >= hvsi_count)
1145 		return -EINVAL;
1146 	hp = &hvsi_ports[console->index];
1147 
1148 	/* give the FSP a chance to change the baud rate when we re-open */
1149 	hvsi_close_protocol(hp);
1150 
1151 	ret = hvsi_handshake(hp);
1152 	if (ret < 0)
1153 		return ret;
1154 
1155 	ret = hvsi_get_mctrl(hp);
1156 	if (ret < 0)
1157 		return ret;
1158 
1159 	ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
1160 	if (ret < 0)
1161 		return ret;
1162 
1163 	hp->flags |= HVSI_CONSOLE;
1164 
1165 	return 0;
1166 }
1167 
1168 static struct console hvsi_console = {
1169 	.name		= "hvsi",
1170 	.write		= hvsi_console_print,
1171 	.device		= hvsi_console_device,
1172 	.setup		= hvsi_console_setup,
1173 	.flags		= CON_PRINTBUFFER,
1174 	.index		= -1,
1175 };
1176 
hvsi_console_init(void)1177 static int __init hvsi_console_init(void)
1178 {
1179 	struct device_node *vty;
1180 
1181 	hvsi_wait = poll_for_state; /* no irqs yet; must poll */
1182 
1183 	/* search device tree for vty nodes */
1184 	for_each_compatible_node(vty, "serial", "hvterm-protocol") {
1185 		struct hvsi_struct *hp;
1186 		const __be32 *vtermno, *irq;
1187 
1188 		vtermno = of_get_property(vty, "reg", NULL);
1189 		irq = of_get_property(vty, "interrupts", NULL);
1190 		if (!vtermno || !irq)
1191 			continue;
1192 
1193 		if (hvsi_count >= MAX_NR_HVSI_CONSOLES) {
1194 			of_node_put(vty);
1195 			break;
1196 		}
1197 
1198 		hp = &hvsi_ports[hvsi_count];
1199 		INIT_DELAYED_WORK(&hp->writer, hvsi_write_worker);
1200 		INIT_WORK(&hp->handshaker, hvsi_handshaker);
1201 		init_waitqueue_head(&hp->emptyq);
1202 		init_waitqueue_head(&hp->stateq);
1203 		spin_lock_init(&hp->lock);
1204 		tty_port_init(&hp->port);
1205 		hp->index = hvsi_count;
1206 		hp->inbuf_end = hp->inbuf;
1207 		hp->state = HVSI_CLOSED;
1208 		hp->vtermno = be32_to_cpup(vtermno);
1209 		hp->virq = irq_create_mapping(NULL, be32_to_cpup(irq));
1210 		if (hp->virq == 0) {
1211 			printk(KERN_ERR "%s: couldn't create irq mapping for 0x%x\n",
1212 			       __func__, be32_to_cpup(irq));
1213 			tty_port_destroy(&hp->port);
1214 			continue;
1215 		}
1216 
1217 		hvsi_count++;
1218 	}
1219 
1220 	if (hvsi_count)
1221 		register_console(&hvsi_console);
1222 	return 0;
1223 }
1224 console_initcall(hvsi_console_init);
1225