1// SPDX-License-Identifier: GPL-2.0
2/*
3 * SCLP VT220 terminal driver.
4 *
5 * Copyright IBM Corp. 2003, 2009
6 *
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/sysrq.h>
17#include <linux/tty.h>
18#include <linux/tty_driver.h>
19#include <linux/tty_flip.h>
20#include <linux/errno.h>
21#include <linux/mm.h>
22#include <linux/major.h>
23#include <linux/console.h>
24#include <linux/kdev_t.h>
25#include <linux/interrupt.h>
26#include <linux/init.h>
27#include <linux/reboot.h>
28#include <linux/slab.h>
29
30#include <linux/uaccess.h>
31#include "sclp.h"
32#include "ctrlchar.h"
33
34#define SCLP_VT220_MAJOR		TTY_MAJOR
35#define SCLP_VT220_MINOR		65
36#define SCLP_VT220_DRIVER_NAME		"sclp_vt220"
37#define SCLP_VT220_DEVICE_NAME		"ttysclp"
38#define SCLP_VT220_CONSOLE_NAME		"ttysclp"
39#define SCLP_VT220_CONSOLE_INDEX	0	/* console=ttysclp0 */
40
41/* Representation of a single write request */
42struct sclp_vt220_request {
43	struct list_head list;
44	struct sclp_req sclp_req;
45	int retry_count;
46};
47
48/* VT220 SCCB */
49struct sclp_vt220_sccb {
50	struct sccb_header header;
51	struct evbuf_header evbuf;
52};
53
54#define SCLP_VT220_MAX_CHARS_PER_BUFFER	(PAGE_SIZE - \
55					 sizeof(struct sclp_vt220_request) - \
56					 sizeof(struct sclp_vt220_sccb))
57
58/* Structures and data needed to register tty driver */
59static struct tty_driver *sclp_vt220_driver;
60
61static struct tty_port sclp_vt220_port;
62
63/* Lock to protect internal data from concurrent access */
64static spinlock_t sclp_vt220_lock;
65
66/* List of empty pages to be used as write request buffers */
67static struct list_head sclp_vt220_empty;
68
69/* List of pending requests */
70static struct list_head sclp_vt220_outqueue;
71
72/* Suspend mode flag */
73static int sclp_vt220_suspended;
74
75/* Flag that output queue is currently running */
76static int sclp_vt220_queue_running;
77
78/* Timer used for delaying write requests to merge subsequent messages into
79 * a single buffer */
80static struct timer_list sclp_vt220_timer;
81
82/* Pointer to current request buffer which has been partially filled but not
83 * yet sent */
84static struct sclp_vt220_request *sclp_vt220_current_request;
85
86/* Number of characters in current request buffer */
87static int sclp_vt220_buffered_chars;
88
89/* Counter controlling core driver initialization. */
90static int __initdata sclp_vt220_init_count;
91
92/* Flag indicating that sclp_vt220_current_request should really
93 * have been already queued but wasn't because the SCLP was processing
94 * another buffer */
95static int sclp_vt220_flush_later;
96
97static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
98static void sclp_vt220_pm_event_fn(struct sclp_register *reg,
99				   enum sclp_pm_event sclp_pm_event);
100static int __sclp_vt220_emit(struct sclp_vt220_request *request);
101static void sclp_vt220_emit_current(void);
102
103/* Registration structure for SCLP output event buffers */
104static struct sclp_register sclp_vt220_register = {
105	.send_mask		= EVTYP_VT220MSG_MASK,
106	.pm_event_fn		= sclp_vt220_pm_event_fn,
107};
108
109/* Registration structure for SCLP input event buffers */
110static struct sclp_register sclp_vt220_register_input = {
111	.receive_mask		= EVTYP_VT220MSG_MASK,
112	.receiver_fn		= sclp_vt220_receiver_fn,
113};
114
115
116/*
117 * Put provided request buffer back into queue and check emit pending
118 * buffers if necessary.
119 */
120static void
121sclp_vt220_process_queue(struct sclp_vt220_request *request)
122{
123	unsigned long flags;
124	void *page;
125
126	do {
127		/* Put buffer back to list of empty buffers */
128		page = request->sclp_req.sccb;
129		spin_lock_irqsave(&sclp_vt220_lock, flags);
130		/* Move request from outqueue to empty queue */
131		list_del(&request->list);
132		list_add_tail((struct list_head *) page, &sclp_vt220_empty);
133		/* Check if there is a pending buffer on the out queue. */
134		request = NULL;
135		if (!list_empty(&sclp_vt220_outqueue))
136			request = list_entry(sclp_vt220_outqueue.next,
137					     struct sclp_vt220_request, list);
138		if (!request || sclp_vt220_suspended) {
139			sclp_vt220_queue_running = 0;
140			spin_unlock_irqrestore(&sclp_vt220_lock, flags);
141			break;
142		}
143		spin_unlock_irqrestore(&sclp_vt220_lock, flags);
144	} while (__sclp_vt220_emit(request));
145	if (request == NULL && sclp_vt220_flush_later)
146		sclp_vt220_emit_current();
147	tty_port_tty_wakeup(&sclp_vt220_port);
148}
149
150#define SCLP_BUFFER_MAX_RETRY		1
151
152/*
153 * Callback through which the result of a write request is reported by the
154 * SCLP.
155 */
156static void
157sclp_vt220_callback(struct sclp_req *request, void *data)
158{
159	struct sclp_vt220_request *vt220_request;
160	struct sclp_vt220_sccb *sccb;
161
162	vt220_request = (struct sclp_vt220_request *) data;
163	if (request->status == SCLP_REQ_FAILED) {
164		sclp_vt220_process_queue(vt220_request);
165		return;
166	}
167	sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
168
169	/* Check SCLP response code and choose suitable action	*/
170	switch (sccb->header.response_code) {
171	case 0x0020 :
172		break;
173
174	case 0x05f0: /* Target resource in improper state */
175		break;
176
177	case 0x0340: /* Contained SCLP equipment check */
178		if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
179			break;
180		/* Remove processed buffers and requeue rest */
181		if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
182			/* Not all buffers were processed */
183			sccb->header.response_code = 0x0000;
184			vt220_request->sclp_req.status = SCLP_REQ_FILLED;
185			if (sclp_add_request(request) == 0)
186				return;
187		}
188		break;
189
190	case 0x0040: /* SCLP equipment check */
191		if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
192			break;
193		sccb->header.response_code = 0x0000;
194		vt220_request->sclp_req.status = SCLP_REQ_FILLED;
195		if (sclp_add_request(request) == 0)
196			return;
197		break;
198
199	default:
200		break;
201	}
202	sclp_vt220_process_queue(vt220_request);
203}
204
205/*
206 * Emit vt220 request buffer to SCLP. Return zero on success, non-zero
207 * otherwise.
208 */
209static int
210__sclp_vt220_emit(struct sclp_vt220_request *request)
211{
212	request->sclp_req.command = SCLP_CMDW_WRITE_EVENT_DATA;
213	request->sclp_req.status = SCLP_REQ_FILLED;
214	request->sclp_req.callback = sclp_vt220_callback;
215	request->sclp_req.callback_data = (void *) request;
216
217	return sclp_add_request(&request->sclp_req);
218}
219
220/*
221 * Queue and emit current request.
222 */
223static void
224sclp_vt220_emit_current(void)
225{
226	unsigned long flags;
227	struct sclp_vt220_request *request;
228	struct sclp_vt220_sccb *sccb;
229
230	spin_lock_irqsave(&sclp_vt220_lock, flags);
231	if (sclp_vt220_current_request) {
232		sccb = (struct sclp_vt220_sccb *)
233				sclp_vt220_current_request->sclp_req.sccb;
234		/* Only emit buffers with content */
235		if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
236			list_add_tail(&sclp_vt220_current_request->list,
237				      &sclp_vt220_outqueue);
238			sclp_vt220_current_request = NULL;
239			if (timer_pending(&sclp_vt220_timer))
240				del_timer(&sclp_vt220_timer);
241		}
242		sclp_vt220_flush_later = 0;
243	}
244	if (sclp_vt220_queue_running || sclp_vt220_suspended)
245		goto out_unlock;
246	if (list_empty(&sclp_vt220_outqueue))
247		goto out_unlock;
248	request = list_first_entry(&sclp_vt220_outqueue,
249				   struct sclp_vt220_request, list);
250	sclp_vt220_queue_running = 1;
251	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
252
253	if (__sclp_vt220_emit(request))
254		sclp_vt220_process_queue(request);
255	return;
256out_unlock:
257	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
258}
259
260#define SCLP_NORMAL_WRITE	0x00
261
262/*
263 * Helper function to initialize a page with the sclp request structure.
264 */
265static struct sclp_vt220_request *
266sclp_vt220_initialize_page(void *page)
267{
268	struct sclp_vt220_request *request;
269	struct sclp_vt220_sccb *sccb;
270
271	/* Place request structure at end of page */
272	request = ((struct sclp_vt220_request *)
273			((addr_t) page + PAGE_SIZE)) - 1;
274	request->retry_count = 0;
275	request->sclp_req.sccb = page;
276	/* SCCB goes at start of page */
277	sccb = (struct sclp_vt220_sccb *) page;
278	memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
279	sccb->header.length = sizeof(struct sclp_vt220_sccb);
280	sccb->header.function_code = SCLP_NORMAL_WRITE;
281	sccb->header.response_code = 0x0000;
282	sccb->evbuf.type = EVTYP_VT220MSG;
283	sccb->evbuf.length = sizeof(struct evbuf_header);
284
285	return request;
286}
287
288static inline unsigned int
289sclp_vt220_space_left(struct sclp_vt220_request *request)
290{
291	struct sclp_vt220_sccb *sccb;
292	sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
293	return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
294	       sccb->header.length;
295}
296
297static inline unsigned int
298sclp_vt220_chars_stored(struct sclp_vt220_request *request)
299{
300	struct sclp_vt220_sccb *sccb;
301	sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
302	return sccb->evbuf.length - sizeof(struct evbuf_header);
303}
304
305/*
306 * Add msg to buffer associated with request. Return the number of characters
307 * added.
308 */
309static int
310sclp_vt220_add_msg(struct sclp_vt220_request *request,
311		   const unsigned char *msg, int count, int convertlf)
312{
313	struct sclp_vt220_sccb *sccb;
314	void *buffer;
315	unsigned char c;
316	int from;
317	int to;
318
319	if (count > sclp_vt220_space_left(request))
320		count = sclp_vt220_space_left(request);
321	if (count <= 0)
322		return 0;
323
324	sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
325	buffer = (void *) ((addr_t) sccb + sccb->header.length);
326
327	if (convertlf) {
328		/* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
329		for (from=0, to=0;
330		     (from < count) && (to < sclp_vt220_space_left(request));
331		     from++) {
332			/* Retrieve character */
333			c = msg[from];
334			/* Perform conversion */
335			if (c == 0x0a) {
336				if (to + 1 < sclp_vt220_space_left(request)) {
337					((unsigned char *) buffer)[to++] = c;
338					((unsigned char *) buffer)[to++] = 0x0d;
339				} else
340					break;
341
342			} else
343				((unsigned char *) buffer)[to++] = c;
344		}
345		sccb->header.length += to;
346		sccb->evbuf.length += to;
347		return from;
348	} else {
349		memcpy(buffer, (const void *) msg, count);
350		sccb->header.length += count;
351		sccb->evbuf.length += count;
352		return count;
353	}
354}
355
356/*
357 * Emit buffer after having waited long enough for more data to arrive.
358 */
359static void
360sclp_vt220_timeout(struct timer_list *unused)
361{
362	sclp_vt220_emit_current();
363}
364
365#define BUFFER_MAX_DELAY	HZ/20
366
367/*
368 * Drop oldest console buffer if sclp_con_drop is set
369 */
370static int
371sclp_vt220_drop_buffer(void)
372{
373	struct list_head *list;
374	struct sclp_vt220_request *request;
375	void *page;
376
377	if (!sclp_console_drop)
378		return 0;
379	list = sclp_vt220_outqueue.next;
380	if (sclp_vt220_queue_running)
381		/* The first element is in I/O */
382		list = list->next;
383	if (list == &sclp_vt220_outqueue)
384		return 0;
385	list_del(list);
386	request = list_entry(list, struct sclp_vt220_request, list);
387	page = request->sclp_req.sccb;
388	list_add_tail((struct list_head *) page, &sclp_vt220_empty);
389	return 1;
390}
391
392/*
393 * Internal implementation of the write function. Write COUNT bytes of data
394 * from memory at BUF
395 * to the SCLP interface. In case that the data does not fit into the current
396 * write buffer, emit the current one and allocate a new one. If there are no
397 * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
398 * is non-zero, the buffer will be scheduled for emitting after a timeout -
399 * otherwise the user has to explicitly call the flush function.
400 * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
401 * buffer should be converted to 0x0a 0x0d. After completion, return the number
402 * of bytes written.
403 */
404static int
405__sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
406		   int convertlf, int may_fail)
407{
408	unsigned long flags;
409	void *page;
410	int written;
411	int overall_written;
412
413	if (count <= 0)
414		return 0;
415	overall_written = 0;
416	spin_lock_irqsave(&sclp_vt220_lock, flags);
417	do {
418		/* Create an sclp output buffer if none exists yet */
419		if (sclp_vt220_current_request == NULL) {
420			if (list_empty(&sclp_vt220_empty))
421				sclp_console_full++;
422			while (list_empty(&sclp_vt220_empty)) {
423				if (may_fail || sclp_vt220_suspended)
424					goto out;
425				if (sclp_vt220_drop_buffer())
426					break;
427				spin_unlock_irqrestore(&sclp_vt220_lock, flags);
428
429				sclp_sync_wait();
430				spin_lock_irqsave(&sclp_vt220_lock, flags);
431			}
432			page = (void *) sclp_vt220_empty.next;
433			list_del((struct list_head *) page);
434			sclp_vt220_current_request =
435				sclp_vt220_initialize_page(page);
436		}
437		/* Try to write the string to the current request buffer */
438		written = sclp_vt220_add_msg(sclp_vt220_current_request,
439					     buf, count, convertlf);
440		overall_written += written;
441		if (written == count)
442			break;
443		/*
444		 * Not all characters could be written to the current
445		 * output buffer. Emit the buffer, create a new buffer
446		 * and then output the rest of the string.
447		 */
448		spin_unlock_irqrestore(&sclp_vt220_lock, flags);
449		sclp_vt220_emit_current();
450		spin_lock_irqsave(&sclp_vt220_lock, flags);
451		buf += written;
452		count -= written;
453	} while (count > 0);
454	/* Setup timer to output current console buffer after some time */
455	if (sclp_vt220_current_request != NULL &&
456	    !timer_pending(&sclp_vt220_timer) && do_schedule) {
457		sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
458		add_timer(&sclp_vt220_timer);
459	}
460out:
461	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
462	return overall_written;
463}
464
465/*
466 * This routine is called by the kernel to write a series of
467 * characters to the tty device.  The characters may come from
468 * user space or kernel space.  This routine will return the
469 * number of characters actually accepted for writing.
470 */
471static int
472sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
473{
474	return __sclp_vt220_write(buf, count, 1, 0, 1);
475}
476
477#define SCLP_VT220_SESSION_ENDED	0x01
478#define	SCLP_VT220_SESSION_STARTED	0x80
479#define SCLP_VT220_SESSION_DATA		0x00
480
481#ifdef CONFIG_MAGIC_SYSRQ
482
483static int sysrq_pressed;
484static struct sysrq_work sysrq;
485
486static void sclp_vt220_reset_session(void)
487{
488	sysrq_pressed = 0;
489}
490
491static void sclp_vt220_handle_input(const char *buffer, unsigned int count)
492{
493	int i;
494
495	for (i = 0; i < count; i++) {
496		/* Handle magic sys request */
497		if (buffer[i] == ('O' ^ 0100)) { /* CTRL-O */
498			/*
499			 * If pressed again, reset sysrq_pressed
500			 * and flip CTRL-O character
501			 */
502			sysrq_pressed = !sysrq_pressed;
503			if (sysrq_pressed)
504				continue;
505		} else if (sysrq_pressed) {
506			sysrq.key = buffer[i];
507			schedule_sysrq_work(&sysrq);
508			sysrq_pressed = 0;
509			continue;
510		}
511		tty_insert_flip_char(&sclp_vt220_port, buffer[i], 0);
512	}
513}
514
515#else
516
517static void sclp_vt220_reset_session(void)
518{
519}
520
521static void sclp_vt220_handle_input(const char *buffer, unsigned int count)
522{
523	tty_insert_flip_string(&sclp_vt220_port, buffer, count);
524}
525
526#endif
527
528/*
529 * Called by the SCLP to report incoming event buffers.
530 */
531static void
532sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
533{
534	char *buffer;
535	unsigned int count;
536
537	buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
538	count = evbuf->length - sizeof(struct evbuf_header);
539
540	switch (*buffer) {
541	case SCLP_VT220_SESSION_ENDED:
542	case SCLP_VT220_SESSION_STARTED:
543		sclp_vt220_reset_session();
544		break;
545	case SCLP_VT220_SESSION_DATA:
546		/* Send input to line discipline */
547		buffer++;
548		count--;
549		sclp_vt220_handle_input(buffer, count);
550		tty_flip_buffer_push(&sclp_vt220_port);
551		break;
552	}
553}
554
555/*
556 * This routine is called when a particular tty device is opened.
557 */
558static int
559sclp_vt220_open(struct tty_struct *tty, struct file *filp)
560{
561	if (tty->count == 1) {
562		tty_port_tty_set(&sclp_vt220_port, tty);
563		sclp_vt220_port.low_latency = 0;
564		if (!tty->winsize.ws_row && !tty->winsize.ws_col) {
565			tty->winsize.ws_row = 24;
566			tty->winsize.ws_col = 80;
567		}
568	}
569	return 0;
570}
571
572/*
573 * This routine is called when a particular tty device is closed.
574 */
575static void
576sclp_vt220_close(struct tty_struct *tty, struct file *filp)
577{
578	if (tty->count == 1)
579		tty_port_tty_set(&sclp_vt220_port, NULL);
580}
581
582/*
583 * This routine is called by the kernel to write a single
584 * character to the tty device.  If the kernel uses this routine,
585 * it must call the flush_chars() routine (if defined) when it is
586 * done stuffing characters into the driver.
587 */
588static int
589sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
590{
591	return __sclp_vt220_write(&ch, 1, 0, 0, 1);
592}
593
594/*
595 * This routine is called by the kernel after it has written a
596 * series of characters to the tty device using put_char().
597 */
598static void
599sclp_vt220_flush_chars(struct tty_struct *tty)
600{
601	if (!sclp_vt220_queue_running)
602		sclp_vt220_emit_current();
603	else
604		sclp_vt220_flush_later = 1;
605}
606
607/*
608 * This routine returns the numbers of characters the tty driver
609 * will accept for queuing to be written.  This number is subject
610 * to change as output buffers get emptied, or if the output flow
611 * control is acted.
612 */
613static int
614sclp_vt220_write_room(struct tty_struct *tty)
615{
616	unsigned long flags;
617	struct list_head *l;
618	int count;
619
620	spin_lock_irqsave(&sclp_vt220_lock, flags);
621	count = 0;
622	if (sclp_vt220_current_request != NULL)
623		count = sclp_vt220_space_left(sclp_vt220_current_request);
624	list_for_each(l, &sclp_vt220_empty)
625		count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
626	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
627	return count;
628}
629
630/*
631 * Return number of buffered chars.
632 */
633static int
634sclp_vt220_chars_in_buffer(struct tty_struct *tty)
635{
636	unsigned long flags;
637	struct list_head *l;
638	struct sclp_vt220_request *r;
639	int count;
640
641	spin_lock_irqsave(&sclp_vt220_lock, flags);
642	count = 0;
643	if (sclp_vt220_current_request != NULL)
644		count = sclp_vt220_chars_stored(sclp_vt220_current_request);
645	list_for_each(l, &sclp_vt220_outqueue) {
646		r = list_entry(l, struct sclp_vt220_request, list);
647		count += sclp_vt220_chars_stored(r);
648	}
649	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
650	return count;
651}
652
653/*
654 * Pass on all buffers to the hardware. Return only when there are no more
655 * buffers pending.
656 */
657static void
658sclp_vt220_flush_buffer(struct tty_struct *tty)
659{
660	sclp_vt220_emit_current();
661}
662
663/* Release allocated pages. */
664static void __init __sclp_vt220_free_pages(void)
665{
666	struct list_head *page, *p;
667
668	list_for_each_safe(page, p, &sclp_vt220_empty) {
669		list_del(page);
670		free_page((unsigned long) page);
671	}
672}
673
674/* Release memory and unregister from sclp core. Controlled by init counting -
675 * only the last invoker will actually perform these actions. */
676static void __init __sclp_vt220_cleanup(void)
677{
678	sclp_vt220_init_count--;
679	if (sclp_vt220_init_count != 0)
680		return;
681	sclp_unregister(&sclp_vt220_register);
682	__sclp_vt220_free_pages();
683	tty_port_destroy(&sclp_vt220_port);
684}
685
686/* Allocate buffer pages and register with sclp core. Controlled by init
687 * counting - only the first invoker will actually perform these actions. */
688static int __init __sclp_vt220_init(int num_pages)
689{
690	void *page;
691	int i;
692	int rc;
693
694	sclp_vt220_init_count++;
695	if (sclp_vt220_init_count != 1)
696		return 0;
697	spin_lock_init(&sclp_vt220_lock);
698	INIT_LIST_HEAD(&sclp_vt220_empty);
699	INIT_LIST_HEAD(&sclp_vt220_outqueue);
700	timer_setup(&sclp_vt220_timer, sclp_vt220_timeout, 0);
701	tty_port_init(&sclp_vt220_port);
702	sclp_vt220_current_request = NULL;
703	sclp_vt220_buffered_chars = 0;
704	sclp_vt220_flush_later = 0;
705
706	/* Allocate pages for output buffering */
707	rc = -ENOMEM;
708	for (i = 0; i < num_pages; i++) {
709		page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
710		if (!page)
711			goto out;
712		list_add_tail(page, &sclp_vt220_empty);
713	}
714	rc = sclp_register(&sclp_vt220_register);
715out:
716	if (rc) {
717		__sclp_vt220_free_pages();
718		sclp_vt220_init_count--;
719		tty_port_destroy(&sclp_vt220_port);
720	}
721	return rc;
722}
723
724static const struct tty_operations sclp_vt220_ops = {
725	.open = sclp_vt220_open,
726	.close = sclp_vt220_close,
727	.write = sclp_vt220_write,
728	.put_char = sclp_vt220_put_char,
729	.flush_chars = sclp_vt220_flush_chars,
730	.write_room = sclp_vt220_write_room,
731	.chars_in_buffer = sclp_vt220_chars_in_buffer,
732	.flush_buffer = sclp_vt220_flush_buffer,
733};
734
735/*
736 * Register driver with SCLP and Linux and initialize internal tty structures.
737 */
738static int __init sclp_vt220_tty_init(void)
739{
740	struct tty_driver *driver;
741	int rc;
742
743	/* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
744	 * symmetry between VM and LPAR systems regarding ttyS1. */
745	driver = alloc_tty_driver(1);
746	if (!driver)
747		return -ENOMEM;
748	rc = __sclp_vt220_init(MAX_KMEM_PAGES);
749	if (rc)
750		goto out_driver;
751
752	driver->driver_name = SCLP_VT220_DRIVER_NAME;
753	driver->name = SCLP_VT220_DEVICE_NAME;
754	driver->major = SCLP_VT220_MAJOR;
755	driver->minor_start = SCLP_VT220_MINOR;
756	driver->type = TTY_DRIVER_TYPE_SYSTEM;
757	driver->subtype = SYSTEM_TYPE_TTY;
758	driver->init_termios = tty_std_termios;
759	driver->flags = TTY_DRIVER_REAL_RAW;
760	tty_set_operations(driver, &sclp_vt220_ops);
761	tty_port_link_device(&sclp_vt220_port, driver, 0);
762
763	rc = tty_register_driver(driver);
764	if (rc)
765		goto out_init;
766	rc = sclp_register(&sclp_vt220_register_input);
767	if (rc)
768		goto out_reg;
769	sclp_vt220_driver = driver;
770	return 0;
771
772out_reg:
773	tty_unregister_driver(driver);
774out_init:
775	__sclp_vt220_cleanup();
776out_driver:
777	put_tty_driver(driver);
778	return rc;
779}
780__initcall(sclp_vt220_tty_init);
781
782static void __sclp_vt220_flush_buffer(void)
783{
784	unsigned long flags;
785
786	sclp_vt220_emit_current();
787	spin_lock_irqsave(&sclp_vt220_lock, flags);
788	if (timer_pending(&sclp_vt220_timer))
789		del_timer(&sclp_vt220_timer);
790	while (sclp_vt220_queue_running) {
791		spin_unlock_irqrestore(&sclp_vt220_lock, flags);
792		sclp_sync_wait();
793		spin_lock_irqsave(&sclp_vt220_lock, flags);
794	}
795	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
796}
797
798/*
799 * Resume console: If there are cached messages, emit them.
800 */
801static void sclp_vt220_resume(void)
802{
803	unsigned long flags;
804
805	spin_lock_irqsave(&sclp_vt220_lock, flags);
806	sclp_vt220_suspended = 0;
807	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
808	sclp_vt220_emit_current();
809}
810
811/*
812 * Suspend console: Set suspend flag and flush console
813 */
814static void sclp_vt220_suspend(void)
815{
816	unsigned long flags;
817
818	spin_lock_irqsave(&sclp_vt220_lock, flags);
819	sclp_vt220_suspended = 1;
820	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
821	__sclp_vt220_flush_buffer();
822}
823
824static void sclp_vt220_pm_event_fn(struct sclp_register *reg,
825				   enum sclp_pm_event sclp_pm_event)
826{
827	switch (sclp_pm_event) {
828	case SCLP_PM_EVENT_FREEZE:
829		sclp_vt220_suspend();
830		break;
831	case SCLP_PM_EVENT_RESTORE:
832	case SCLP_PM_EVENT_THAW:
833		sclp_vt220_resume();
834		break;
835	}
836}
837
838#ifdef CONFIG_SCLP_VT220_CONSOLE
839
840static void
841sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
842{
843	__sclp_vt220_write((const unsigned char *) buf, count, 1, 1, 0);
844}
845
846static struct tty_driver *
847sclp_vt220_con_device(struct console *c, int *index)
848{
849	*index = 0;
850	return sclp_vt220_driver;
851}
852
853static int
854sclp_vt220_notify(struct notifier_block *self,
855			  unsigned long event, void *data)
856{
857	__sclp_vt220_flush_buffer();
858	return NOTIFY_OK;
859}
860
861static struct notifier_block on_panic_nb = {
862	.notifier_call = sclp_vt220_notify,
863	.priority = 1,
864};
865
866static struct notifier_block on_reboot_nb = {
867	.notifier_call = sclp_vt220_notify,
868	.priority = 1,
869};
870
871/* Structure needed to register with printk */
872static struct console sclp_vt220_console =
873{
874	.name = SCLP_VT220_CONSOLE_NAME,
875	.write = sclp_vt220_con_write,
876	.device = sclp_vt220_con_device,
877	.flags = CON_PRINTBUFFER,
878	.index = SCLP_VT220_CONSOLE_INDEX
879};
880
881static int __init
882sclp_vt220_con_init(void)
883{
884	int rc;
885
886	rc = __sclp_vt220_init(sclp_console_pages);
887	if (rc)
888		return rc;
889	/* Attach linux console */
890	atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
891	register_reboot_notifier(&on_reboot_nb);
892	register_console(&sclp_vt220_console);
893	return 0;
894}
895
896console_initcall(sclp_vt220_con_init);
897#endif /* CONFIG_SCLP_VT220_CONSOLE */
898
899