xref: /openbmc/linux/drivers/s390/char/sclp_tty.c (revision 95713967)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *    SCLP line mode terminal driver.
4  *
5  *  S390 version
6  *    Copyright IBM Corp. 1999
7  *    Author(s): Martin Peschke <mpeschke@de.ibm.com>
8  *		 Martin Schwidefsky <schwidefsky@de.ibm.com>
9  */
10 
11 #include <linux/kmod.h>
12 #include <linux/tty.h>
13 #include <linux/tty_driver.h>
14 #include <linux/tty_flip.h>
15 #include <linux/err.h>
16 #include <linux/init.h>
17 #include <linux/interrupt.h>
18 #include <linux/gfp.h>
19 #include <linux/uaccess.h>
20 
21 #include "ctrlchar.h"
22 #include "sclp.h"
23 #include "sclp_rw.h"
24 #include "sclp_tty.h"
25 
26 /*
27  * size of a buffer that collects single characters coming in
28  * via sclp_tty_put_char()
29  */
30 #define SCLP_TTY_BUF_SIZE 512
31 
32 /*
33  * There is exactly one SCLP terminal, so we can keep things simple
34  * and allocate all variables statically.
35  */
36 
37 /* Lock to guard over changes to global variables. */
38 static DEFINE_SPINLOCK(sclp_tty_lock);
39 /* List of free pages that can be used for console output buffering. */
40 static LIST_HEAD(sclp_tty_pages);
41 /* List of full struct sclp_buffer structures ready for output. */
42 static LIST_HEAD(sclp_tty_outqueue);
43 /* Counter how many buffers are emitted. */
44 static int sclp_tty_buffer_count;
45 /* Pointer to current console buffer. */
46 static struct sclp_buffer *sclp_ttybuf;
47 /* Timer for delayed output of console messages. */
48 static struct timer_list sclp_tty_timer;
49 
50 static struct tty_port sclp_port;
51 static u8 sclp_tty_chars[SCLP_TTY_BUF_SIZE];
52 static unsigned short int sclp_tty_chars_count;
53 
54 struct tty_driver *sclp_tty_driver;
55 
56 static int sclp_tty_tolower;
57 
58 #define SCLP_TTY_COLUMNS 320
59 #define SPACES_PER_TAB 8
60 #define CASE_DELIMITER 0x6c /* to separate upper and lower case (% in EBCDIC) */
61 
62 /* This routine is called whenever we try to open a SCLP terminal. */
63 static int
sclp_tty_open(struct tty_struct * tty,struct file * filp)64 sclp_tty_open(struct tty_struct *tty, struct file *filp)
65 {
66 	tty_port_tty_set(&sclp_port, tty);
67 	tty->driver_data = NULL;
68 	return 0;
69 }
70 
71 /* This routine is called when the SCLP terminal is closed. */
72 static void
sclp_tty_close(struct tty_struct * tty,struct file * filp)73 sclp_tty_close(struct tty_struct *tty, struct file *filp)
74 {
75 	if (tty->count > 1)
76 		return;
77 	tty_port_tty_set(&sclp_port, NULL);
78 }
79 
80 /*
81  * This routine returns the numbers of characters the tty driver
82  * will accept for queuing to be written.  This number is subject
83  * to change as output buffers get emptied, or if the output flow
84  * control is acted. This is not an exact number because not every
85  * character needs the same space in the sccb. The worst case is
86  * a string of newlines. Every newline creates a new message which
87  * needs 82 bytes.
88  */
89 static unsigned int
sclp_tty_write_room(struct tty_struct * tty)90 sclp_tty_write_room (struct tty_struct *tty)
91 {
92 	unsigned long flags;
93 	struct list_head *l;
94 	unsigned int count;
95 
96 	spin_lock_irqsave(&sclp_tty_lock, flags);
97 	count = 0;
98 	if (sclp_ttybuf != NULL)
99 		count = sclp_buffer_space(sclp_ttybuf) / sizeof(struct msg_buf);
100 	list_for_each(l, &sclp_tty_pages)
101 		count += NR_EMPTY_MSG_PER_SCCB;
102 	spin_unlock_irqrestore(&sclp_tty_lock, flags);
103 	return count;
104 }
105 
106 static void
sclp_ttybuf_callback(struct sclp_buffer * buffer,int rc)107 sclp_ttybuf_callback(struct sclp_buffer *buffer, int rc)
108 {
109 	unsigned long flags;
110 	void *page;
111 
112 	do {
113 		page = sclp_unmake_buffer(buffer);
114 		spin_lock_irqsave(&sclp_tty_lock, flags);
115 		/* Remove buffer from outqueue */
116 		list_del(&buffer->list);
117 		sclp_tty_buffer_count--;
118 		list_add_tail((struct list_head *) page, &sclp_tty_pages);
119 		/* Check if there is a pending buffer on the out queue. */
120 		buffer = NULL;
121 		if (!list_empty(&sclp_tty_outqueue))
122 			buffer = list_entry(sclp_tty_outqueue.next,
123 					    struct sclp_buffer, list);
124 		spin_unlock_irqrestore(&sclp_tty_lock, flags);
125 	} while (buffer && sclp_emit_buffer(buffer, sclp_ttybuf_callback));
126 
127 	tty_port_tty_wakeup(&sclp_port);
128 }
129 
130 static inline void
__sclp_ttybuf_emit(struct sclp_buffer * buffer)131 __sclp_ttybuf_emit(struct sclp_buffer *buffer)
132 {
133 	unsigned long flags;
134 	int count;
135 	int rc;
136 
137 	spin_lock_irqsave(&sclp_tty_lock, flags);
138 	list_add_tail(&buffer->list, &sclp_tty_outqueue);
139 	count = sclp_tty_buffer_count++;
140 	spin_unlock_irqrestore(&sclp_tty_lock, flags);
141 	if (count)
142 		return;
143 	rc = sclp_emit_buffer(buffer, sclp_ttybuf_callback);
144 	if (rc)
145 		sclp_ttybuf_callback(buffer, rc);
146 }
147 
148 /*
149  * When this routine is called from the timer then we flush the
150  * temporary write buffer.
151  */
152 static void
sclp_tty_timeout(struct timer_list * unused)153 sclp_tty_timeout(struct timer_list *unused)
154 {
155 	unsigned long flags;
156 	struct sclp_buffer *buf;
157 
158 	spin_lock_irqsave(&sclp_tty_lock, flags);
159 	buf = sclp_ttybuf;
160 	sclp_ttybuf = NULL;
161 	spin_unlock_irqrestore(&sclp_tty_lock, flags);
162 
163 	if (buf != NULL) {
164 		__sclp_ttybuf_emit(buf);
165 	}
166 }
167 
168 /*
169  * Write a string to the sclp tty.
170  */
sclp_tty_write_string(const u8 * str,int count,int may_fail)171 static int sclp_tty_write_string(const u8 *str, int count, int may_fail)
172 {
173 	unsigned long flags;
174 	void *page;
175 	int written;
176 	int overall_written;
177 	struct sclp_buffer *buf;
178 
179 	if (count <= 0)
180 		return 0;
181 	overall_written = 0;
182 	spin_lock_irqsave(&sclp_tty_lock, flags);
183 	do {
184 		/* Create a sclp output buffer if none exists yet */
185 		if (sclp_ttybuf == NULL) {
186 			while (list_empty(&sclp_tty_pages)) {
187 				spin_unlock_irqrestore(&sclp_tty_lock, flags);
188 				if (may_fail)
189 					goto out;
190 				else
191 					sclp_sync_wait();
192 				spin_lock_irqsave(&sclp_tty_lock, flags);
193 			}
194 			page = sclp_tty_pages.next;
195 			list_del((struct list_head *) page);
196 			sclp_ttybuf = sclp_make_buffer(page, SCLP_TTY_COLUMNS,
197 						       SPACES_PER_TAB);
198 		}
199 		/* try to write the string to the current output buffer */
200 		written = sclp_write(sclp_ttybuf, str, count);
201 		overall_written += written;
202 		if (written == count)
203 			break;
204 		/*
205 		 * Not all characters could be written to the current
206 		 * output buffer. Emit the buffer, create a new buffer
207 		 * and then output the rest of the string.
208 		 */
209 		buf = sclp_ttybuf;
210 		sclp_ttybuf = NULL;
211 		spin_unlock_irqrestore(&sclp_tty_lock, flags);
212 		__sclp_ttybuf_emit(buf);
213 		spin_lock_irqsave(&sclp_tty_lock, flags);
214 		str += written;
215 		count -= written;
216 	} while (count > 0);
217 	/* Setup timer to output current console buffer after 1/10 second */
218 	if (sclp_ttybuf && sclp_chars_in_buffer(sclp_ttybuf) &&
219 	    !timer_pending(&sclp_tty_timer)) {
220 		mod_timer(&sclp_tty_timer, jiffies + HZ / 10);
221 	}
222 	spin_unlock_irqrestore(&sclp_tty_lock, flags);
223 out:
224 	return overall_written;
225 }
226 
227 /*
228  * This routine is called by the kernel to write a series of characters to the
229  * tty device. The characters may come from user space or kernel space. This
230  * routine will return the number of characters actually accepted for writing.
231  */
232 static ssize_t
sclp_tty_write(struct tty_struct * tty,const u8 * buf,size_t count)233 sclp_tty_write(struct tty_struct *tty, const u8 *buf, size_t count)
234 {
235 	if (sclp_tty_chars_count > 0) {
236 		sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
237 		sclp_tty_chars_count = 0;
238 	}
239 	return sclp_tty_write_string(buf, count, 1);
240 }
241 
242 /*
243  * This routine is called by the kernel to write a single character to the tty
244  * device. If the kernel uses this routine, it must call the flush_chars()
245  * routine (if defined) when it is done stuffing characters into the driver.
246  *
247  * Characters provided to sclp_tty_put_char() are buffered by the SCLP driver.
248  * If the given character is a '\n' the contents of the SCLP write buffer
249  * - including previous characters from sclp_tty_put_char() and strings from
250  * sclp_write() without final '\n' - will be written.
251  */
252 static int
sclp_tty_put_char(struct tty_struct * tty,u8 ch)253 sclp_tty_put_char(struct tty_struct *tty, u8 ch)
254 {
255 	sclp_tty_chars[sclp_tty_chars_count++] = ch;
256 	if (ch == '\n' || sclp_tty_chars_count >= SCLP_TTY_BUF_SIZE) {
257 		sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
258 		sclp_tty_chars_count = 0;
259 	}
260 	return 1;
261 }
262 
263 /*
264  * This routine is called by the kernel after it has written a series of
265  * characters to the tty device using put_char().
266  */
267 static void
sclp_tty_flush_chars(struct tty_struct * tty)268 sclp_tty_flush_chars(struct tty_struct *tty)
269 {
270 	if (sclp_tty_chars_count > 0) {
271 		sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
272 		sclp_tty_chars_count = 0;
273 	}
274 }
275 
276 /*
277  * This routine returns the number of characters in the write buffer of the
278  * SCLP driver. The provided number includes all characters that are stored
279  * in the SCCB (will be written next time the SCLP is not busy) as well as
280  * characters in the write buffer (will not be written as long as there is a
281  * final line feed missing).
282  */
283 static unsigned int
sclp_tty_chars_in_buffer(struct tty_struct * tty)284 sclp_tty_chars_in_buffer(struct tty_struct *tty)
285 {
286 	unsigned long flags;
287 	struct sclp_buffer *t;
288 	unsigned int count = 0;
289 
290 	spin_lock_irqsave(&sclp_tty_lock, flags);
291 	if (sclp_ttybuf != NULL)
292 		count = sclp_chars_in_buffer(sclp_ttybuf);
293 	list_for_each_entry(t, &sclp_tty_outqueue, list) {
294 		count += sclp_chars_in_buffer(t);
295 	}
296 	spin_unlock_irqrestore(&sclp_tty_lock, flags);
297 	return count;
298 }
299 
300 /*
301  * removes all content from buffers of low level driver
302  */
303 static void
sclp_tty_flush_buffer(struct tty_struct * tty)304 sclp_tty_flush_buffer(struct tty_struct *tty)
305 {
306 	if (sclp_tty_chars_count > 0) {
307 		sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
308 		sclp_tty_chars_count = 0;
309 	}
310 }
311 
312 /*
313  * push input to tty
314  */
315 static void
sclp_tty_input(unsigned char * buf,unsigned int count)316 sclp_tty_input(unsigned char* buf, unsigned int count)
317 {
318 	struct tty_struct *tty = tty_port_tty_get(&sclp_port);
319 	unsigned int cchar;
320 
321 	/*
322 	 * If this tty driver is currently closed
323 	 * then throw the received input away.
324 	 */
325 	if (tty == NULL)
326 		return;
327 	cchar = ctrlchar_handle(buf, count, tty);
328 	switch (cchar & CTRLCHAR_MASK) {
329 	case CTRLCHAR_SYSRQ:
330 		break;
331 	case CTRLCHAR_CTRL:
332 		tty_insert_flip_char(&sclp_port, cchar, TTY_NORMAL);
333 		tty_flip_buffer_push(&sclp_port);
334 		break;
335 	case CTRLCHAR_NONE:
336 		/* send (normal) input to line discipline */
337 		if (count < 2 ||
338 		    (strncmp((const char *) buf + count - 2, "^n", 2) &&
339 		     strncmp((const char *) buf + count - 2, "\252n", 2))) {
340 			/* add the auto \n */
341 			tty_insert_flip_string(&sclp_port, buf, count);
342 			tty_insert_flip_char(&sclp_port, '\n', TTY_NORMAL);
343 		} else
344 			tty_insert_flip_string(&sclp_port, buf, count - 2);
345 		tty_flip_buffer_push(&sclp_port);
346 		break;
347 	}
348 	tty_kref_put(tty);
349 }
350 
351 /*
352  * get a EBCDIC string in upper/lower case,
353  * find out characters in lower/upper case separated by a special character,
354  * modifiy original string,
355  * returns length of resulting string
356  */
sclp_switch_cases(unsigned char * buf,int count)357 static int sclp_switch_cases(unsigned char *buf, int count)
358 {
359 	unsigned char *ip, *op;
360 	int toggle;
361 
362 	/* initially changing case is off */
363 	toggle = 0;
364 	ip = op = buf;
365 	while (count-- > 0) {
366 		/* compare with special character */
367 		if (*ip == CASE_DELIMITER) {
368 			/* followed by another special character? */
369 			if (count && ip[1] == CASE_DELIMITER) {
370 				/*
371 				 * ... then put a single copy of the special
372 				 * character to the output string
373 				 */
374 				*op++ = *ip++;
375 				count--;
376 			} else
377 				/*
378 				 * ... special character follower by a normal
379 				 * character toggles the case change behaviour
380 				 */
381 				toggle = ~toggle;
382 			/* skip special character */
383 			ip++;
384 		} else
385 			/* not the special character */
386 			if (toggle)
387 				/* but case switching is on */
388 				if (sclp_tty_tolower)
389 					/* switch to uppercase */
390 					*op++ = _ebc_toupper[(int) *ip++];
391 				else
392 					/* switch to lowercase */
393 					*op++ = _ebc_tolower[(int) *ip++];
394 			else
395 				/* no case switching, copy the character */
396 				*op++ = *ip++;
397 	}
398 	/* return length of reformatted string. */
399 	return op - buf;
400 }
401 
sclp_get_input(struct gds_subvector * sv)402 static void sclp_get_input(struct gds_subvector *sv)
403 {
404 	unsigned char *str;
405 	int count;
406 
407 	str = (unsigned char *) (sv + 1);
408 	count = sv->length - sizeof(*sv);
409 	if (sclp_tty_tolower)
410 		EBC_TOLOWER(str, count);
411 	count = sclp_switch_cases(str, count);
412 	/* convert EBCDIC to ASCII (modify original input in SCCB) */
413 	sclp_ebcasc_str(str, count);
414 
415 	/* transfer input to high level driver */
416 	sclp_tty_input(str, count);
417 }
418 
sclp_eval_selfdeftextmsg(struct gds_subvector * sv)419 static inline void sclp_eval_selfdeftextmsg(struct gds_subvector *sv)
420 {
421 	void *end;
422 
423 	end = (void *) sv + sv->length;
424 	for (sv = sv + 1; (void *) sv < end; sv = (void *) sv + sv->length)
425 		if (sv->key == 0x30)
426 			sclp_get_input(sv);
427 }
428 
sclp_eval_textcmd(struct gds_vector * v)429 static inline void sclp_eval_textcmd(struct gds_vector *v)
430 {
431 	struct gds_subvector *sv;
432 	void *end;
433 
434 	end = (void *) v + v->length;
435 	for (sv = (struct gds_subvector *) (v + 1);
436 	     (void *) sv < end; sv = (void *) sv + sv->length)
437 		if (sv->key == GDS_KEY_SELFDEFTEXTMSG)
438 			sclp_eval_selfdeftextmsg(sv);
439 
440 }
441 
sclp_eval_cpmsu(struct gds_vector * v)442 static inline void sclp_eval_cpmsu(struct gds_vector *v)
443 {
444 	void *end;
445 
446 	end = (void *) v + v->length;
447 	for (v = v + 1; (void *) v < end; v = (void *) v + v->length)
448 		if (v->gds_id == GDS_ID_TEXTCMD)
449 			sclp_eval_textcmd(v);
450 }
451 
452 
sclp_eval_mdsmu(struct gds_vector * v)453 static inline void sclp_eval_mdsmu(struct gds_vector *v)
454 {
455 	v = sclp_find_gds_vector(v + 1, (void *) v + v->length, GDS_ID_CPMSU);
456 	if (v)
457 		sclp_eval_cpmsu(v);
458 }
459 
sclp_tty_receiver(struct evbuf_header * evbuf)460 static void sclp_tty_receiver(struct evbuf_header *evbuf)
461 {
462 	struct gds_vector *v;
463 
464 	v = sclp_find_gds_vector(evbuf + 1, (void *) evbuf + evbuf->length,
465 				 GDS_ID_MDSMU);
466 	if (v)
467 		sclp_eval_mdsmu(v);
468 }
469 
470 static void
sclp_tty_state_change(struct sclp_register * reg)471 sclp_tty_state_change(struct sclp_register *reg)
472 {
473 }
474 
475 static struct sclp_register sclp_input_event =
476 {
477 	.receive_mask = EVTYP_OPCMD_MASK | EVTYP_PMSGCMD_MASK,
478 	.state_change_fn = sclp_tty_state_change,
479 	.receiver_fn = sclp_tty_receiver
480 };
481 
482 static const struct tty_operations sclp_ops = {
483 	.open = sclp_tty_open,
484 	.close = sclp_tty_close,
485 	.write = sclp_tty_write,
486 	.put_char = sclp_tty_put_char,
487 	.flush_chars = sclp_tty_flush_chars,
488 	.write_room = sclp_tty_write_room,
489 	.chars_in_buffer = sclp_tty_chars_in_buffer,
490 	.flush_buffer = sclp_tty_flush_buffer,
491 };
492 
493 static int __init
sclp_tty_init(void)494 sclp_tty_init(void)
495 {
496 	struct tty_driver *driver;
497 	void *page;
498 	int i;
499 	int rc;
500 
501 	/* z/VM multiplexes the line mode output on the 32xx screen */
502 	if (MACHINE_IS_VM && !CONSOLE_IS_SCLP)
503 		return 0;
504 	if (!sclp.has_linemode)
505 		return 0;
506 	driver = tty_alloc_driver(1, TTY_DRIVER_REAL_RAW);
507 	if (IS_ERR(driver))
508 		return PTR_ERR(driver);
509 
510 	rc = sclp_rw_init();
511 	if (rc) {
512 		tty_driver_kref_put(driver);
513 		return rc;
514 	}
515 	/* Allocate pages for output buffering */
516 	for (i = 0; i < MAX_KMEM_PAGES; i++) {
517 		page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
518 		if (page == NULL) {
519 			tty_driver_kref_put(driver);
520 			return -ENOMEM;
521 		}
522 		list_add_tail((struct list_head *) page, &sclp_tty_pages);
523 	}
524 	timer_setup(&sclp_tty_timer, sclp_tty_timeout, 0);
525 	sclp_ttybuf = NULL;
526 	sclp_tty_buffer_count = 0;
527 	if (MACHINE_IS_VM) {
528 		/* case input lines to lowercase */
529 		sclp_tty_tolower = 1;
530 	}
531 	sclp_tty_chars_count = 0;
532 
533 	rc = sclp_register(&sclp_input_event);
534 	if (rc) {
535 		tty_driver_kref_put(driver);
536 		return rc;
537 	}
538 
539 	tty_port_init(&sclp_port);
540 
541 	driver->driver_name = "sclp_line";
542 	driver->name = "sclp_line";
543 	driver->major = TTY_MAJOR;
544 	driver->minor_start = 64;
545 	driver->type = TTY_DRIVER_TYPE_SYSTEM;
546 	driver->subtype = SYSTEM_TYPE_TTY;
547 	driver->init_termios = tty_std_termios;
548 	driver->init_termios.c_iflag = IGNBRK | IGNPAR;
549 	driver->init_termios.c_oflag = ONLCR;
550 	driver->init_termios.c_lflag = ISIG | ECHO;
551 	tty_set_operations(driver, &sclp_ops);
552 	tty_port_link_device(&sclp_port, driver, 0);
553 	rc = tty_register_driver(driver);
554 	if (rc) {
555 		tty_driver_kref_put(driver);
556 		tty_port_destroy(&sclp_port);
557 		return rc;
558 	}
559 	sclp_tty_driver = driver;
560 	return 0;
561 }
562 device_initcall(sclp_tty_init);
563