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. */
38static DEFINE_SPINLOCK(sclp_tty_lock);
39/* List of free pages that can be used for console output buffering. */
40static LIST_HEAD(sclp_tty_pages);
41/* List of full struct sclp_buffer structures ready for output. */
42static LIST_HEAD(sclp_tty_outqueue);
43/* Counter how many buffers are emitted. */
44static int sclp_tty_buffer_count;
45/* Pointer to current console buffer. */
46static struct sclp_buffer *sclp_ttybuf;
47/* Timer for delayed output of console messages. */
48static struct timer_list sclp_tty_timer;
49
50static struct tty_port sclp_port;
51static u8 sclp_tty_chars[SCLP_TTY_BUF_SIZE];
52static unsigned short int sclp_tty_chars_count;
53
54struct tty_driver *sclp_tty_driver;
55
56static 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. */
63static int
64sclp_tty_open(struct tty_struct *tty, struct file *filp)
65{
66 tty_port_tty_set(port: &sclp_port, tty);
67 tty->driver_data = NULL;
68 return 0;
69}
70
71/* This routine is called when the SCLP terminal is closed. */
72static void
73sclp_tty_close(struct tty_struct *tty, struct file *filp)
74{
75 if (tty->count > 1)
76 return;
77 tty_port_tty_set(port: &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 */
89static unsigned int
90sclp_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(lock: &sclp_tty_lock, flags);
103 return count;
104}
105
106static void
107sclp_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(entry: &buffer->list);
117 sclp_tty_buffer_count--;
118 list_add_tail(new: (struct list_head *) page, head: &sclp_tty_pages);
119 /* Check if there is a pending buffer on the out queue. */
120 buffer = NULL;
121 if (!list_empty(head: &sclp_tty_outqueue))
122 buffer = list_entry(sclp_tty_outqueue.next,
123 struct sclp_buffer, list);
124 spin_unlock_irqrestore(lock: &sclp_tty_lock, flags);
125 } while (buffer && sclp_emit_buffer(buffer, sclp_ttybuf_callback));
126
127 tty_port_tty_wakeup(port: &sclp_port);
128}
129
130static inline void
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(new: &buffer->list, head: &sclp_tty_outqueue);
139 count = sclp_tty_buffer_count++;
140 spin_unlock_irqrestore(lock: &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 */
152static void
153sclp_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(lock: &sclp_tty_lock, flags);
162
163 if (buf != NULL) {
164 __sclp_ttybuf_emit(buffer: buf);
165 }
166}
167
168/*
169 * Write a string to the sclp tty.
170 */
171static 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(head: &sclp_tty_pages)) {
187 spin_unlock_irqrestore(lock: &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(entry: (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(buffer: 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(lock: &sclp_tty_lock, flags);
212 __sclp_ttybuf_emit(buffer: 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(timer: &sclp_tty_timer)) {
220 mod_timer(timer: &sclp_tty_timer, expires: jiffies + HZ / 10);
221 }
222 spin_unlock_irqrestore(lock: &sclp_tty_lock, flags);
223out:
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 */
232static ssize_t
233sclp_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(str: sclp_tty_chars, count: sclp_tty_chars_count, may_fail: 0);
237 sclp_tty_chars_count = 0;
238 }
239 return sclp_tty_write_string(str: buf, count, may_fail: 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 */
252static int
253sclp_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(str: sclp_tty_chars, count: sclp_tty_chars_count, may_fail: 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 */
267static void
268sclp_tty_flush_chars(struct tty_struct *tty)
269{
270 if (sclp_tty_chars_count > 0) {
271 sclp_tty_write_string(str: sclp_tty_chars, count: sclp_tty_chars_count, may_fail: 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 */
283static unsigned int
284sclp_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(lock: &sclp_tty_lock, flags);
297 return count;
298}
299
300/*
301 * removes all content from buffers of low level driver
302 */
303static void
304sclp_tty_flush_buffer(struct tty_struct *tty)
305{
306 if (sclp_tty_chars_count > 0) {
307 sclp_tty_write_string(str: sclp_tty_chars, count: sclp_tty_chars_count, may_fail: 0);
308 sclp_tty_chars_count = 0;
309 }
310}
311
312/*
313 * push input to tty
314 */
315static void
316sclp_tty_input(unsigned char* buf, unsigned int count)
317{
318 struct tty_struct *tty = tty_port_tty_get(port: &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, len: count, tty);
328 switch (cchar & CTRLCHAR_MASK) {
329 case CTRLCHAR_SYSRQ:
330 break;
331 case CTRLCHAR_CTRL:
332 tty_insert_flip_char(port: &sclp_port, ch: cchar, TTY_NORMAL);
333 tty_flip_buffer_push(port: &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(port: &sclp_port, chars: buf, size: count);
342 tty_insert_flip_char(port: &sclp_port, ch: '\n', TTY_NORMAL);
343 } else
344 tty_insert_flip_string(port: &sclp_port, chars: buf, size: count - 2);
345 tty_flip_buffer_push(port: &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 */
357static 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
402static 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(buf: str, count);
412 /* convert EBCDIC to ASCII (modify original input in SCCB) */
413 sclp_ebcasc_str(str, nr: count);
414
415 /* transfer input to high level driver */
416 sclp_tty_input(buf: str, count);
417}
418
419static 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
429static 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
442static 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
453static inline void sclp_eval_mdsmu(struct gds_vector *v)
454{
455 v = sclp_find_gds_vector(start: v + 1, end: (void *) v + v->length, GDS_ID_CPMSU);
456 if (v)
457 sclp_eval_cpmsu(v);
458}
459
460static void sclp_tty_receiver(struct evbuf_header *evbuf)
461{
462 struct gds_vector *v;
463
464 v = sclp_find_gds_vector(start: evbuf + 1, end: (void *) evbuf + evbuf->length,
465 GDS_ID_MDSMU);
466 if (v)
467 sclp_eval_mdsmu(v);
468}
469
470static void
471sclp_tty_state_change(struct sclp_register *reg)
472{
473}
474
475static 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
482static 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
493static int __init
494sclp_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(ptr: driver))
508 return PTR_ERR(ptr: 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(new: (struct list_head *) page, head: &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(reg: &sclp_input_event);
534 if (rc) {
535 tty_driver_kref_put(driver);
536 return rc;
537 }
538
539 tty_port_init(port: &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, op: &sclp_ops);
552 tty_port_link_device(port: &sclp_port, driver, index: 0);
553 rc = tty_register_driver(driver);
554 if (rc) {
555 tty_driver_kref_put(driver);
556 tty_port_destroy(port: &sclp_port);
557 return rc;
558 }
559 sclp_tty_driver = driver;
560 return 0;
561}
562device_initcall(sclp_tty_init);
563

source code of linux/drivers/s390/char/sclp_tty.c