GNU Linux-libre 5.10.219-gnu1
[releases.git] / drivers / tty / hvc / hvsi.c
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/spinlock.h>
30 #include <linux/sysrq.h>
31 #include <linux/tty.h>
32 #include <linux/tty_flip.h>
33 #include <asm/hvcall.h>
34 #include <asm/hvconsole.h>
35 #include <asm/prom.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
99 static inline int is_console(struct hvsi_struct *hp)
100 {
101         return hp->flags & HVSI_CONSOLE;
102 }
103
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
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
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
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
145 static inline int len_packet(const uint8_t *packet)
146 {
147         return (int)((struct hvsi_header *)packet)->len;
148 }
149
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
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 */
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
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
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
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
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
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 */
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
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
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
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  */
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
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  */
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 */
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 */
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
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
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 */
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
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
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
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
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
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
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 */
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
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
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 */
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 */
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
893 static 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
900 static 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
907 static int hvsi_write(struct tty_struct *tty,
908                      const unsigned char *buf, int count)
909 {
910         struct hvsi_struct *hp = tty->driver_data;
911         const char *source = buf;
912         unsigned long flags;
913         int total = 0;
914         int origcount = count;
915
916         spin_lock_irqsave(&hp->lock, flags);
917
918         pr_debug("%s: %i chars in buffer\n", __func__, hp->n_outbuf);
919
920         if (!is_open(hp)) {
921                 /* we're either closing or not yet open; don't accept data */
922                 pr_debug("%s: not open\n", __func__);
923                 goto out;
924         }
925
926         /*
927          * when the hypervisor buffer (16K) fills, data will stay in hp->outbuf
928          * and hvsi_write_worker will be scheduled. subsequent hvsi_write() calls
929          * will see there is no room in outbuf and return.
930          */
931         while ((count > 0) && (hvsi_write_room(tty) > 0)) {
932                 int chunksize = min(count, hvsi_write_room(tty));
933
934                 BUG_ON(hp->n_outbuf < 0);
935                 memcpy(hp->outbuf + hp->n_outbuf, source, chunksize);
936                 hp->n_outbuf += chunksize;
937
938                 total += chunksize;
939                 source += chunksize;
940                 count -= chunksize;
941                 hvsi_push(hp);
942         }
943
944         if (hp->n_outbuf > 0) {
945                 /*
946                  * we weren't able to write it all to the hypervisor.
947                  * schedule another push attempt.
948                  */
949                 schedule_delayed_work(&hp->writer, 10);
950         }
951
952 out:
953         spin_unlock_irqrestore(&hp->lock, flags);
954
955         if (total != origcount)
956                 pr_debug("%s: wanted %i, only wrote %i\n", __func__, origcount,
957                         total);
958
959         return total;
960 }
961
962 /*
963  * I have never seen throttle or unthrottle called, so this little throttle
964  * buffering scheme may or may not work.
965  */
966 static void hvsi_throttle(struct tty_struct *tty)
967 {
968         struct hvsi_struct *hp = tty->driver_data;
969
970         pr_debug("%s\n", __func__);
971
972         h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE);
973 }
974
975 static void hvsi_unthrottle(struct tty_struct *tty)
976 {
977         struct hvsi_struct *hp = tty->driver_data;
978         unsigned long flags;
979
980         pr_debug("%s\n", __func__);
981
982         spin_lock_irqsave(&hp->lock, flags);
983         if (hp->n_throttle) {
984                 hvsi_send_overflow(hp);
985                 tty_flip_buffer_push(&hp->port);
986         }
987         spin_unlock_irqrestore(&hp->lock, flags);
988
989
990         h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
991 }
992
993 static int hvsi_tiocmget(struct tty_struct *tty)
994 {
995         struct hvsi_struct *hp = tty->driver_data;
996
997         hvsi_get_mctrl(hp);
998         return hp->mctrl;
999 }
1000
1001 static int hvsi_tiocmset(struct tty_struct *tty,
1002                                 unsigned int set, unsigned int clear)
1003 {
1004         struct hvsi_struct *hp = tty->driver_data;
1005         unsigned long flags;
1006         uint16_t new_mctrl;
1007
1008         /* we can only alter DTR */
1009         clear &= TIOCM_DTR;
1010         set &= TIOCM_DTR;
1011
1012         spin_lock_irqsave(&hp->lock, flags);
1013
1014         new_mctrl = (hp->mctrl & ~clear) | set;
1015
1016         if (hp->mctrl != new_mctrl) {
1017                 hvsi_set_mctrl(hp, new_mctrl);
1018                 hp->mctrl = new_mctrl;
1019         }
1020         spin_unlock_irqrestore(&hp->lock, flags);
1021
1022         return 0;
1023 }
1024
1025
1026 static const struct tty_operations hvsi_ops = {
1027         .open = hvsi_open,
1028         .close = hvsi_close,
1029         .write = hvsi_write,
1030         .hangup = hvsi_hangup,
1031         .write_room = hvsi_write_room,
1032         .chars_in_buffer = hvsi_chars_in_buffer,
1033         .throttle = hvsi_throttle,
1034         .unthrottle = hvsi_unthrottle,
1035         .tiocmget = hvsi_tiocmget,
1036         .tiocmset = hvsi_tiocmset,
1037 };
1038
1039 static int __init hvsi_init(void)
1040 {
1041         int i, ret;
1042
1043         hvsi_driver = alloc_tty_driver(hvsi_count);
1044         if (!hvsi_driver)
1045                 return -ENOMEM;
1046
1047         hvsi_driver->driver_name = "hvsi";
1048         hvsi_driver->name = "hvsi";
1049         hvsi_driver->major = HVSI_MAJOR;
1050         hvsi_driver->minor_start = HVSI_MINOR;
1051         hvsi_driver->type = TTY_DRIVER_TYPE_SYSTEM;
1052         hvsi_driver->init_termios = tty_std_termios;
1053         hvsi_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL;
1054         hvsi_driver->init_termios.c_ispeed = 9600;
1055         hvsi_driver->init_termios.c_ospeed = 9600;
1056         hvsi_driver->flags = TTY_DRIVER_REAL_RAW;
1057         tty_set_operations(hvsi_driver, &hvsi_ops);
1058
1059         for (i=0; i < hvsi_count; i++) {
1060                 struct hvsi_struct *hp = &hvsi_ports[i];
1061                 int ret = 1;
1062
1063                 tty_port_link_device(&hp->port, hvsi_driver, i);
1064
1065                 ret = request_irq(hp->virq, hvsi_interrupt, 0, "hvsi", hp);
1066                 if (ret)
1067                         printk(KERN_ERR "HVSI: couldn't reserve irq 0x%x (error %i)\n",
1068                                 hp->virq, ret);
1069         }
1070         hvsi_wait = wait_for_state; /* irqs active now */
1071
1072         ret = tty_register_driver(hvsi_driver);
1073         if (ret) {
1074                 pr_err("Couldn't register hvsi console driver\n");
1075                 goto err_free_irq;
1076         }
1077
1078         printk(KERN_DEBUG "HVSI: registered %i devices\n", hvsi_count);
1079
1080         return 0;
1081 err_free_irq:
1082         hvsi_wait = poll_for_state;
1083         for (i = 0; i < hvsi_count; i++) {
1084                 struct hvsi_struct *hp = &hvsi_ports[i];
1085
1086                 free_irq(hp->virq, hp);
1087         }
1088         tty_driver_kref_put(hvsi_driver);
1089
1090         return ret;
1091 }
1092 device_initcall(hvsi_init);
1093
1094 /***** console (not tty) code: *****/
1095
1096 static void hvsi_console_print(struct console *console, const char *buf,
1097                 unsigned int count)
1098 {
1099         struct hvsi_struct *hp = &hvsi_ports[console->index];
1100         char c[HVSI_MAX_OUTGOING_DATA] __ALIGNED__;
1101         unsigned int i = 0, n = 0;
1102         int ret, donecr = 0;
1103
1104         mb();
1105         if (!is_open(hp))
1106                 return;
1107
1108         /*
1109          * ugh, we have to translate LF -> CRLF ourselves, in place.
1110          * copied from hvc_console.c:
1111          */
1112         while (count > 0 || i > 0) {
1113                 if (count > 0 && i < sizeof(c)) {
1114                         if (buf[n] == '\n' && !donecr) {
1115                                 c[i++] = '\r';
1116                                 donecr = 1;
1117                         } else {
1118                                 c[i++] = buf[n++];
1119                                 donecr = 0;
1120                                 --count;
1121                         }
1122                 } else {
1123                         ret = hvsi_put_chars(hp, c, i);
1124                         if (ret < 0)
1125                                 i = 0;
1126                         i -= ret;
1127                 }
1128         }
1129 }
1130
1131 static struct tty_driver *hvsi_console_device(struct console *console,
1132         int *index)
1133 {
1134         *index = console->index;
1135         return hvsi_driver;
1136 }
1137
1138 static int __init hvsi_console_setup(struct console *console, char *options)
1139 {
1140         struct hvsi_struct *hp;
1141         int ret;
1142
1143         if (console->index < 0 || console->index >= hvsi_count)
1144                 return -EINVAL;
1145         hp = &hvsi_ports[console->index];
1146
1147         /* give the FSP a chance to change the baud rate when we re-open */
1148         hvsi_close_protocol(hp);
1149
1150         ret = hvsi_handshake(hp);
1151         if (ret < 0)
1152                 return ret;
1153
1154         ret = hvsi_get_mctrl(hp);
1155         if (ret < 0)
1156                 return ret;
1157
1158         ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
1159         if (ret < 0)
1160                 return ret;
1161
1162         hp->flags |= HVSI_CONSOLE;
1163
1164         return 0;
1165 }
1166
1167 static struct console hvsi_console = {
1168         .name           = "hvsi",
1169         .write          = hvsi_console_print,
1170         .device         = hvsi_console_device,
1171         .setup          = hvsi_console_setup,
1172         .flags          = CON_PRINTBUFFER,
1173         .index          = -1,
1174 };
1175
1176 static int __init hvsi_console_init(void)
1177 {
1178         struct device_node *vty;
1179
1180         hvsi_wait = poll_for_state; /* no irqs yet; must poll */
1181
1182         /* search device tree for vty nodes */
1183         for_each_compatible_node(vty, "serial", "hvterm-protocol") {
1184                 struct hvsi_struct *hp;
1185                 const __be32 *vtermno, *irq;
1186
1187                 vtermno = of_get_property(vty, "reg", NULL);
1188                 irq = of_get_property(vty, "interrupts", NULL);
1189                 if (!vtermno || !irq)
1190                         continue;
1191
1192                 if (hvsi_count >= MAX_NR_HVSI_CONSOLES) {
1193                         of_node_put(vty);
1194                         break;
1195                 }
1196
1197                 hp = &hvsi_ports[hvsi_count];
1198                 INIT_DELAYED_WORK(&hp->writer, hvsi_write_worker);
1199                 INIT_WORK(&hp->handshaker, hvsi_handshaker);
1200                 init_waitqueue_head(&hp->emptyq);
1201                 init_waitqueue_head(&hp->stateq);
1202                 spin_lock_init(&hp->lock);
1203                 tty_port_init(&hp->port);
1204                 hp->index = hvsi_count;
1205                 hp->inbuf_end = hp->inbuf;
1206                 hp->state = HVSI_CLOSED;
1207                 hp->vtermno = be32_to_cpup(vtermno);
1208                 hp->virq = irq_create_mapping(NULL, be32_to_cpup(irq));
1209                 if (hp->virq == 0) {
1210                         printk(KERN_ERR "%s: couldn't create irq mapping for 0x%x\n",
1211                                __func__, be32_to_cpup(irq));
1212                         tty_port_destroy(&hp->port);
1213                         continue;
1214                 }
1215
1216                 hvsi_count++;
1217         }
1218
1219         if (hvsi_count)
1220                 register_console(&hvsi_console);
1221         return 0;
1222 }
1223 console_initcall(hvsi_console_init);