Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
[linux-2.6] / drivers / s390 / char / sclp_vt220.c
1 /*
2  *  drivers/s390/char/sclp_vt220.c
3  *    SCLP VT220 terminal driver.
4  *
5  *  S390 version
6  *    Copyright (C) 2003 IBM Deutschland Entwicklung GmbH, IBM Corporation
7  *    Author(s): Peter Oberparleiter <Peter.Oberparleiter@de.ibm.com>
8  */
9
10 #include <linux/module.h>
11 #include <linux/spinlock.h>
12 #include <linux/list.h>
13 #include <linux/wait.h>
14 #include <linux/timer.h>
15 #include <linux/kernel.h>
16 #include <linux/tty.h>
17 #include <linux/tty_driver.h>
18 #include <linux/tty_flip.h>
19 #include <linux/errno.h>
20 #include <linux/mm.h>
21 #include <linux/major.h>
22 #include <linux/console.h>
23 #include <linux/kdev_t.h>
24 #include <linux/bootmem.h>
25 #include <linux/interrupt.h>
26 #include <linux/init.h>
27 #include <asm/uaccess.h>
28 #include "sclp.h"
29
30 #define SCLP_VT220_PRINT_HEADER         "sclp vt220 tty driver: "
31 #define SCLP_VT220_MAJOR                TTY_MAJOR
32 #define SCLP_VT220_MINOR                65
33 #define SCLP_VT220_DRIVER_NAME          "sclp_vt220"
34 #define SCLP_VT220_DEVICE_NAME          "ttysclp"
35 #define SCLP_VT220_CONSOLE_NAME         "ttyS"
36 #define SCLP_VT220_CONSOLE_INDEX        1       /* console=ttyS1 */
37 #define SCLP_VT220_BUF_SIZE             80
38
39 /* Representation of a single write request */
40 struct sclp_vt220_request {
41         struct list_head list;
42         struct sclp_req sclp_req;
43         int retry_count;
44 };
45
46 /* VT220 SCCB */
47 struct sclp_vt220_sccb {
48         struct sccb_header header;
49         struct evbuf_header evbuf;
50 };
51
52 #define SCLP_VT220_MAX_CHARS_PER_BUFFER (PAGE_SIZE - \
53                                          sizeof(struct sclp_vt220_request) - \
54                                          sizeof(struct sclp_vt220_sccb))
55
56 /* Structures and data needed to register tty driver */
57 static struct tty_driver *sclp_vt220_driver;
58
59 /* The tty_struct that the kernel associated with us */
60 static struct tty_struct *sclp_vt220_tty;
61
62 /* Lock to protect internal data from concurrent access */
63 static spinlock_t sclp_vt220_lock;
64
65 /* List of empty pages to be used as write request buffers */
66 static struct list_head sclp_vt220_empty;
67
68 /* List of pending requests */
69 static struct list_head sclp_vt220_outqueue;
70
71 /* Number of requests in outqueue */
72 static int sclp_vt220_outqueue_count;
73
74 /* Wait queue used to delay write requests while we've run out of buffers */
75 static wait_queue_head_t sclp_vt220_waitq;
76
77 /* Timer used for delaying write requests to merge subsequent messages into
78  * a single buffer */
79 static struct timer_list sclp_vt220_timer;
80
81 /* Pointer to current request buffer which has been partially filled but not
82  * yet sent */
83 static struct sclp_vt220_request *sclp_vt220_current_request;
84
85 /* Number of characters in current request buffer */
86 static int sclp_vt220_buffered_chars;
87
88 /* Flag indicating whether this driver has already been initialized */
89 static int sclp_vt220_initialized = 0;
90
91 /* Flag indicating that sclp_vt220_current_request should really
92  * have been already queued but wasn't because the SCLP was processing
93  * another buffer */
94 static int sclp_vt220_flush_later;
95
96 static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
97 static int __sclp_vt220_emit(struct sclp_vt220_request *request);
98 static void sclp_vt220_emit_current(void);
99
100 /* Registration structure for our interest in SCLP event buffers */
101 static struct sclp_register sclp_vt220_register = {
102         .send_mask              = EVTYP_VT220MSG_MASK,
103         .receive_mask           = EVTYP_VT220MSG_MASK,
104         .state_change_fn        = NULL,
105         .receiver_fn            = sclp_vt220_receiver_fn
106 };
107
108
109 /*
110  * Put provided request buffer back into queue and check emit pending
111  * buffers if necessary.
112  */
113 static void
114 sclp_vt220_process_queue(struct sclp_vt220_request *request)
115 {
116         unsigned long flags;
117         void *page;
118
119         do {
120                 /* Put buffer back to list of empty buffers */
121                 page = request->sclp_req.sccb;
122                 spin_lock_irqsave(&sclp_vt220_lock, flags);
123                 /* Move request from outqueue to empty queue */
124                 list_del(&request->list);
125                 sclp_vt220_outqueue_count--;
126                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
127                 /* Check if there is a pending buffer on the out queue. */
128                 request = NULL;
129                 if (!list_empty(&sclp_vt220_outqueue))
130                         request = list_entry(sclp_vt220_outqueue.next,
131                                              struct sclp_vt220_request, list);
132                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
133         } while (request && __sclp_vt220_emit(request));
134         if (request == NULL && sclp_vt220_flush_later)
135                 sclp_vt220_emit_current();
136         wake_up(&sclp_vt220_waitq);
137         /* Check if the tty needs a wake up call */
138         if (sclp_vt220_tty != NULL) {
139                 tty_wakeup(sclp_vt220_tty);
140         }
141 }
142
143 #define SCLP_BUFFER_MAX_RETRY           1
144
145 /*
146  * Callback through which the result of a write request is reported by the
147  * SCLP.
148  */
149 static void
150 sclp_vt220_callback(struct sclp_req *request, void *data)
151 {
152         struct sclp_vt220_request *vt220_request;
153         struct sclp_vt220_sccb *sccb;
154
155         vt220_request = (struct sclp_vt220_request *) data;
156         if (request->status == SCLP_REQ_FAILED) {
157                 sclp_vt220_process_queue(vt220_request);
158                 return;
159         }
160         sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
161
162         /* Check SCLP response code and choose suitable action  */
163         switch (sccb->header.response_code) {
164         case 0x0020 :
165                 break;
166
167         case 0x05f0: /* Target resource in improper state */
168                 break;
169
170         case 0x0340: /* Contained SCLP equipment check */
171                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
172                         break;
173                 /* Remove processed buffers and requeue rest */
174                 if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
175                         /* Not all buffers were processed */
176                         sccb->header.response_code = 0x0000;
177                         vt220_request->sclp_req.status = SCLP_REQ_FILLED;
178                         if (sclp_add_request(request) == 0)
179                                 return;
180                 }
181                 break;
182
183         case 0x0040: /* SCLP equipment check */
184                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
185                         break;
186                 sccb->header.response_code = 0x0000;
187                 vt220_request->sclp_req.status = SCLP_REQ_FILLED;
188                 if (sclp_add_request(request) == 0)
189                         return;
190                 break;
191
192         default:
193                 break;
194         }
195         sclp_vt220_process_queue(vt220_request);
196 }
197
198 /*
199  * Emit vt220 request buffer to SCLP. Return zero on success, non-zero
200  * otherwise.
201  */
202 static int
203 __sclp_vt220_emit(struct sclp_vt220_request *request)
204 {
205         if (!(sclp_vt220_register.sclp_send_mask & EVTYP_VT220MSG_MASK)) {
206                 request->sclp_req.status = SCLP_REQ_FAILED;
207                 return -EIO;
208         }
209         request->sclp_req.command = SCLP_CMDW_WRITE_EVENT_DATA;
210         request->sclp_req.status = SCLP_REQ_FILLED;
211         request->sclp_req.callback = sclp_vt220_callback;
212         request->sclp_req.callback_data = (void *) request;
213
214         return sclp_add_request(&request->sclp_req);
215 }
216
217 /*
218  * Queue and emit given request.
219  */
220 static void
221 sclp_vt220_emit(struct sclp_vt220_request *request)
222 {
223         unsigned long flags;
224         int count;
225
226         spin_lock_irqsave(&sclp_vt220_lock, flags);
227         list_add_tail(&request->list, &sclp_vt220_outqueue);
228         count = sclp_vt220_outqueue_count++;
229         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
230         /* Emit only the first buffer immediately - callback takes care of
231          * the rest */
232         if (count == 0 && __sclp_vt220_emit(request))
233                 sclp_vt220_process_queue(request);
234 }
235
236 /*
237  * Queue and emit current request. Return zero on success, non-zero otherwise.
238  */
239 static void
240 sclp_vt220_emit_current(void)
241 {
242         unsigned long flags;
243         struct sclp_vt220_request *request;
244         struct sclp_vt220_sccb *sccb;
245
246         spin_lock_irqsave(&sclp_vt220_lock, flags);
247         request = NULL;
248         if (sclp_vt220_current_request != NULL) {
249                 sccb = (struct sclp_vt220_sccb *) 
250                                 sclp_vt220_current_request->sclp_req.sccb;
251                 /* Only emit buffers with content */
252                 if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
253                         request = sclp_vt220_current_request;
254                         sclp_vt220_current_request = NULL;
255                         if (timer_pending(&sclp_vt220_timer))
256                                 del_timer(&sclp_vt220_timer);
257                 }
258                 sclp_vt220_flush_later = 0;
259         }
260         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
261         if (request != NULL)
262                 sclp_vt220_emit(request);
263 }
264
265 #define SCLP_NORMAL_WRITE       0x00
266
267 /*
268  * Helper function to initialize a page with the sclp request structure.
269  */
270 static struct sclp_vt220_request *
271 sclp_vt220_initialize_page(void *page)
272 {
273         struct sclp_vt220_request *request;
274         struct sclp_vt220_sccb *sccb;
275
276         /* Place request structure at end of page */
277         request = ((struct sclp_vt220_request *)
278                         ((addr_t) page + PAGE_SIZE)) - 1;
279         request->retry_count = 0;
280         request->sclp_req.sccb = page;
281         /* SCCB goes at start of page */
282         sccb = (struct sclp_vt220_sccb *) page;
283         memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
284         sccb->header.length = sizeof(struct sclp_vt220_sccb);
285         sccb->header.function_code = SCLP_NORMAL_WRITE;
286         sccb->header.response_code = 0x0000;
287         sccb->evbuf.type = EVTYP_VT220MSG;
288         sccb->evbuf.length = sizeof(struct evbuf_header);
289
290         return request;
291 }
292
293 static inline unsigned int
294 sclp_vt220_space_left(struct sclp_vt220_request *request)
295 {
296         struct sclp_vt220_sccb *sccb;
297         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
298         return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
299                sccb->header.length;
300 }
301
302 static inline unsigned int
303 sclp_vt220_chars_stored(struct sclp_vt220_request *request)
304 {
305         struct sclp_vt220_sccb *sccb;
306         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
307         return sccb->evbuf.length - sizeof(struct evbuf_header);
308 }
309
310 /*
311  * Add msg to buffer associated with request. Return the number of characters
312  * added.
313  */
314 static int
315 sclp_vt220_add_msg(struct sclp_vt220_request *request,
316                    const unsigned char *msg, int count, int convertlf)
317 {
318         struct sclp_vt220_sccb *sccb;
319         void *buffer;
320         unsigned char c;
321         int from;
322         int to;
323
324         if (count > sclp_vt220_space_left(request))
325                 count = sclp_vt220_space_left(request);
326         if (count <= 0)
327                 return 0;
328
329         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
330         buffer = (void *) ((addr_t) sccb + sccb->header.length);
331
332         if (convertlf) {
333                 /* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
334                 for (from=0, to=0;
335                      (from < count) && (to < sclp_vt220_space_left(request));
336                      from++) {
337                         /* Retrieve character */
338                         c = msg[from];
339                         /* Perform conversion */
340                         if (c == 0x0a) {
341                                 if (to + 1 < sclp_vt220_space_left(request)) {
342                                         ((unsigned char *) buffer)[to++] = c;
343                                         ((unsigned char *) buffer)[to++] = 0x0d;
344                                 } else
345                                         break;
346
347                         } else
348                                 ((unsigned char *) buffer)[to++] = c;
349                 }
350                 sccb->header.length += to;
351                 sccb->evbuf.length += to;
352                 return from;
353         } else {
354                 memcpy(buffer, (const void *) msg, count);
355                 sccb->header.length += count;
356                 sccb->evbuf.length += count;
357                 return count;
358         }
359 }
360
361 /*
362  * Emit buffer after having waited long enough for more data to arrive.
363  */
364 static void
365 sclp_vt220_timeout(unsigned long data)
366 {
367         sclp_vt220_emit_current();
368 }
369
370 #define BUFFER_MAX_DELAY        HZ/2
371
372 /* 
373  * Internal implementation of the write function. Write COUNT bytes of data
374  * from memory at BUF
375  * to the SCLP interface. In case that the data does not fit into the current
376  * write buffer, emit the current one and allocate a new one. If there are no
377  * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
378  * is non-zero, the buffer will be scheduled for emitting after a timeout -
379  * otherwise the user has to explicitly call the flush function.
380  * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
381  * buffer should be converted to 0x0a 0x0d. After completion, return the number
382  * of bytes written.
383  */
384 static int
385 __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
386                    int convertlf)
387 {
388         unsigned long flags;
389         void *page;
390         int written;
391         int overall_written;
392
393         if (count <= 0)
394                 return 0;
395         overall_written = 0;
396         spin_lock_irqsave(&sclp_vt220_lock, flags);
397         do {
398                 /* Create a sclp output buffer if none exists yet */
399                 if (sclp_vt220_current_request == NULL) {
400                         while (list_empty(&sclp_vt220_empty)) {
401                                 spin_unlock_irqrestore(&sclp_vt220_lock,
402                                                        flags);
403                                 if (in_interrupt())
404                                         sclp_sync_wait();
405                                 else
406                                         wait_event(sclp_vt220_waitq,
407                                                 !list_empty(&sclp_vt220_empty));
408                                 spin_lock_irqsave(&sclp_vt220_lock, flags);
409                         }
410                         page = (void *) sclp_vt220_empty.next;
411                         list_del((struct list_head *) page);
412                         sclp_vt220_current_request =
413                                 sclp_vt220_initialize_page(page);
414                 }
415                 /* Try to write the string to the current request buffer */
416                 written = sclp_vt220_add_msg(sclp_vt220_current_request,
417                                              buf, count, convertlf);
418                 overall_written += written;
419                 if (written == count)
420                         break;
421                 /*
422                  * Not all characters could be written to the current
423                  * output buffer. Emit the buffer, create a new buffer
424                  * and then output the rest of the string.
425                  */
426                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
427                 sclp_vt220_emit_current();
428                 spin_lock_irqsave(&sclp_vt220_lock, flags);
429                 buf += written;
430                 count -= written;
431         } while (count > 0);
432         /* Setup timer to output current console buffer after some time */
433         if (sclp_vt220_current_request != NULL &&
434             !timer_pending(&sclp_vt220_timer) && do_schedule) {
435                 sclp_vt220_timer.function = sclp_vt220_timeout;
436                 sclp_vt220_timer.data = 0UL;
437                 sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
438                 add_timer(&sclp_vt220_timer);
439         }
440         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
441         return overall_written;
442 }
443
444 /*
445  * This routine is called by the kernel to write a series of
446  * characters to the tty device.  The characters may come from
447  * user space or kernel space.  This routine will return the
448  * number of characters actually accepted for writing.
449  */
450 static int
451 sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
452 {
453         return __sclp_vt220_write(buf, count, 1, 0);
454 }
455
456 #define SCLP_VT220_SESSION_ENDED        0x01
457 #define SCLP_VT220_SESSION_STARTED      0x80
458 #define SCLP_VT220_SESSION_DATA         0x00
459
460 /*
461  * Called by the SCLP to report incoming event buffers.
462  */
463 static void
464 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
465 {
466         char *buffer;
467         unsigned int count;
468
469         /* Ignore input if device is not open */
470         if (sclp_vt220_tty == NULL)
471                 return;
472
473         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
474         count = evbuf->length - sizeof(struct evbuf_header);
475
476         switch (*buffer) {
477         case SCLP_VT220_SESSION_ENDED:
478         case SCLP_VT220_SESSION_STARTED:
479                 break;
480         case SCLP_VT220_SESSION_DATA:
481                 /* Send input to line discipline */
482                 buffer++;
483                 count--;
484                 tty_insert_flip_string(sclp_vt220_tty, buffer, count);
485                 tty_flip_buffer_push(sclp_vt220_tty);
486                 break;
487         }
488 }
489
490 /*
491  * This routine is called when a particular tty device is opened.
492  */
493 static int
494 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
495 {
496         if (tty->count == 1) {
497                 sclp_vt220_tty = tty;
498                 tty->driver_data = kmalloc(SCLP_VT220_BUF_SIZE, GFP_KERNEL);
499                 if (tty->driver_data == NULL)
500                         return -ENOMEM;
501                 tty->low_latency = 0;
502         }
503         return 0;
504 }
505
506 /*
507  * This routine is called when a particular tty device is closed.
508  */
509 static void
510 sclp_vt220_close(struct tty_struct *tty, struct file *filp)
511 {
512         if (tty->count == 1) {
513                 sclp_vt220_tty = NULL;
514                 kfree(tty->driver_data);
515                 tty->driver_data = NULL;
516         }
517 }
518
519 /*
520  * This routine is called by the kernel to write a single
521  * character to the tty device.  If the kernel uses this routine,
522  * it must call the flush_chars() routine (if defined) when it is
523  * done stuffing characters into the driver.
524  *
525  * NOTE: include/linux/tty_driver.h specifies that a character should be
526  * ignored if there is no room in the queue. This driver implements a different
527  * semantic in that it will block when there is no more room left.
528  */
529 static void
530 sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
531 {
532         __sclp_vt220_write(&ch, 1, 0, 0);
533 }
534
535 /*
536  * This routine is called by the kernel after it has written a
537  * series of characters to the tty device using put_char().  
538  */
539 static void
540 sclp_vt220_flush_chars(struct tty_struct *tty)
541 {
542         if (sclp_vt220_outqueue_count == 0)
543                 sclp_vt220_emit_current();
544         else
545                 sclp_vt220_flush_later = 1;
546 }
547
548 /*
549  * This routine returns the numbers of characters the tty driver
550  * will accept for queuing to be written.  This number is subject
551  * to change as output buffers get emptied, or if the output flow
552  * control is acted.
553  */
554 static int
555 sclp_vt220_write_room(struct tty_struct *tty)
556 {
557         unsigned long flags;
558         struct list_head *l;
559         int count;
560
561         spin_lock_irqsave(&sclp_vt220_lock, flags);
562         count = 0;
563         if (sclp_vt220_current_request != NULL)
564                 count = sclp_vt220_space_left(sclp_vt220_current_request);
565         list_for_each(l, &sclp_vt220_empty)
566                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
567         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
568         return count;
569 }
570
571 /*
572  * Return number of buffered chars.
573  */
574 static int
575 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
576 {
577         unsigned long flags;
578         struct list_head *l;
579         struct sclp_vt220_request *r;
580         int count;
581
582         spin_lock_irqsave(&sclp_vt220_lock, flags);
583         count = 0;
584         if (sclp_vt220_current_request != NULL)
585                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
586         list_for_each(l, &sclp_vt220_outqueue) {
587                 r = list_entry(l, struct sclp_vt220_request, list);
588                 count += sclp_vt220_chars_stored(r);
589         }
590         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
591         return count;
592 }
593
594 static void
595 __sclp_vt220_flush_buffer(void)
596 {
597         unsigned long flags;
598
599         sclp_vt220_emit_current();
600         spin_lock_irqsave(&sclp_vt220_lock, flags);
601         if (timer_pending(&sclp_vt220_timer))
602                 del_timer(&sclp_vt220_timer);
603         while (sclp_vt220_outqueue_count > 0) {
604                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
605                 sclp_sync_wait();
606                 spin_lock_irqsave(&sclp_vt220_lock, flags);
607         }
608         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
609 }
610
611 /*
612  * Pass on all buffers to the hardware. Return only when there are no more
613  * buffers pending.
614  */
615 static void
616 sclp_vt220_flush_buffer(struct tty_struct *tty)
617 {
618         sclp_vt220_emit_current();
619 }
620
621 /*
622  * Initialize all relevant components and register driver with system.
623  */
624 static int
625 __sclp_vt220_init(int early)
626 {
627         void *page;
628         int i;
629
630         if (sclp_vt220_initialized)
631                 return 0;
632         sclp_vt220_initialized = 1;
633         spin_lock_init(&sclp_vt220_lock);
634         INIT_LIST_HEAD(&sclp_vt220_empty);
635         INIT_LIST_HEAD(&sclp_vt220_outqueue);
636         init_waitqueue_head(&sclp_vt220_waitq);
637         init_timer(&sclp_vt220_timer);
638         sclp_vt220_current_request = NULL;
639         sclp_vt220_buffered_chars = 0;
640         sclp_vt220_outqueue_count = 0;
641         sclp_vt220_tty = NULL;
642         sclp_vt220_flush_later = 0;
643
644         /* Allocate pages for output buffering */
645         for (i = 0; i < (early ? MAX_CONSOLE_PAGES : MAX_KMEM_PAGES); i++) {
646                 if (early)
647                         page = alloc_bootmem_low_pages(PAGE_SIZE);
648                 else
649                         page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
650                 if (!page)
651                         return -ENOMEM;
652                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
653         }
654         return 0;
655 }
656
657 static const struct tty_operations sclp_vt220_ops = {
658         .open = sclp_vt220_open,
659         .close = sclp_vt220_close,
660         .write = sclp_vt220_write,
661         .put_char = sclp_vt220_put_char,
662         .flush_chars = sclp_vt220_flush_chars,
663         .write_room = sclp_vt220_write_room,
664         .chars_in_buffer = sclp_vt220_chars_in_buffer,
665         .flush_buffer = sclp_vt220_flush_buffer
666 };
667
668 /*
669  * Register driver with SCLP and Linux and initialize internal tty structures.
670  */
671 static int __init
672 sclp_vt220_tty_init(void)
673 {
674         struct tty_driver *driver;
675         int rc;
676
677         /* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
678          * symmetry between VM and LPAR systems regarding ttyS1. */
679         driver = alloc_tty_driver(1);
680         if (!driver)
681                 return -ENOMEM;
682         rc = __sclp_vt220_init(0);
683         if (rc) {
684                 put_tty_driver(driver);
685                 return rc;
686         }
687         rc = sclp_register(&sclp_vt220_register);
688         if (rc) {
689                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
690                        "could not register tty - "
691                        "sclp_register returned %d\n", rc);
692                 put_tty_driver(driver);
693                 return rc;
694         }
695
696         driver->owner = THIS_MODULE;
697         driver->driver_name = SCLP_VT220_DRIVER_NAME;
698         driver->name = SCLP_VT220_DEVICE_NAME;
699         driver->major = SCLP_VT220_MAJOR;
700         driver->minor_start = SCLP_VT220_MINOR;
701         driver->type = TTY_DRIVER_TYPE_SYSTEM;
702         driver->subtype = SYSTEM_TYPE_TTY;
703         driver->init_termios = tty_std_termios;
704         driver->flags = TTY_DRIVER_REAL_RAW;
705         tty_set_operations(driver, &sclp_vt220_ops);
706
707         rc = tty_register_driver(driver);
708         if (rc) {
709                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
710                        "could not register tty - "
711                        "tty_register_driver returned %d\n", rc);
712                 put_tty_driver(driver);
713                 return rc;
714         }
715         sclp_vt220_driver = driver;
716         return 0;
717 }
718
719 module_init(sclp_vt220_tty_init);
720
721 #ifdef CONFIG_SCLP_VT220_CONSOLE
722
723 static void
724 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
725 {
726         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1);
727 }
728
729 static struct tty_driver *
730 sclp_vt220_con_device(struct console *c, int *index)
731 {
732         *index = 0;
733         return sclp_vt220_driver;
734 }
735
736 /*
737  * This routine is called from panic when the kernel is going to give up.
738  * We have to make sure that all buffers will be flushed to the SCLP.
739  * Note that this function may be called from within an interrupt context.
740  */
741 static void
742 sclp_vt220_con_unblank(void)
743 {
744         __sclp_vt220_flush_buffer();
745 }
746
747 /* Structure needed to register with printk */
748 static struct console sclp_vt220_console =
749 {
750         .name = SCLP_VT220_CONSOLE_NAME,
751         .write = sclp_vt220_con_write,
752         .device = sclp_vt220_con_device,
753         .unblank = sclp_vt220_con_unblank,
754         .flags = CON_PRINTBUFFER,
755         .index = SCLP_VT220_CONSOLE_INDEX
756 };
757
758 static int __init
759 sclp_vt220_con_init(void)
760 {
761         int rc;
762
763         if (!CONSOLE_IS_SCLP)
764                 return 0;
765         rc = __sclp_vt220_init(1);
766         if (rc)
767                 return rc;
768         /* Attach linux console */
769         register_console(&sclp_vt220_console);
770         return 0;
771 }
772
773 console_initcall(sclp_vt220_con_init);
774 #endif /* CONFIG_SCLP_VT220_CONSOLE */
775