1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* |
3 | * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM |
4 | * Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM |
5 | * Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp. |
6 | * Copyright (C) 2004 IBM Corporation |
7 | * |
8 | * Additional Author(s): |
9 | * Ryan S. Arnold <rsa@us.ibm.com> |
10 | */ |
11 | |
12 | #include <linux/console.h> |
13 | #include <linux/cpumask.h> |
14 | #include <linux/init.h> |
15 | #include <linux/kbd_kern.h> |
16 | #include <linux/kernel.h> |
17 | #include <linux/kthread.h> |
18 | #include <linux/list.h> |
19 | #include <linux/major.h> |
20 | #include <linux/atomic.h> |
21 | #include <linux/sysrq.h> |
22 | #include <linux/tty.h> |
23 | #include <linux/tty_flip.h> |
24 | #include <linux/sched.h> |
25 | #include <linux/spinlock.h> |
26 | #include <linux/delay.h> |
27 | #include <linux/freezer.h> |
28 | #include <linux/slab.h> |
29 | #include <linux/serial_core.h> |
30 | |
31 | #include <linux/uaccess.h> |
32 | |
33 | #include "hvc_console.h" |
34 | |
35 | #define HVC_MAJOR 229 |
36 | #define HVC_MINOR 0 |
37 | |
38 | /* |
39 | * Wait this long per iteration while trying to push buffered data to the |
40 | * hypervisor before allowing the tty to complete a close operation. |
41 | */ |
42 | #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */ |
43 | |
44 | /* |
45 | * These sizes are most efficient for vio, because they are the |
46 | * native transfer size. We could make them selectable in the |
47 | * future to better deal with backends that want other buffer sizes. |
48 | */ |
49 | #define N_OUTBUF 16 |
50 | #define N_INBUF 16 |
51 | |
52 | #define __ALIGNED__ __attribute__((__aligned__(L1_CACHE_BYTES))) |
53 | |
54 | static struct tty_driver *hvc_driver; |
55 | static struct task_struct *hvc_task; |
56 | |
57 | /* Picks up late kicks after list walk but before schedule() */ |
58 | static int hvc_kicked; |
59 | |
60 | /* hvc_init is triggered from hvc_alloc, i.e. only when actually used */ |
61 | static atomic_t hvc_needs_init __read_mostly = ATOMIC_INIT(-1); |
62 | |
63 | static int hvc_init(void); |
64 | |
65 | #ifdef CONFIG_MAGIC_SYSRQ |
66 | static int sysrq_pressed; |
67 | #endif |
68 | |
69 | /* dynamic list of hvc_struct instances */ |
70 | static LIST_HEAD(hvc_structs); |
71 | |
72 | /* |
73 | * Protect the list of hvc_struct instances from inserts and removals during |
74 | * list traversal. |
75 | */ |
76 | static DEFINE_MUTEX(hvc_structs_mutex); |
77 | |
78 | /* |
79 | * This value is used to assign a tty->index value to a hvc_struct based |
80 | * upon order of exposure via hvc_probe(), when we can not match it to |
81 | * a console candidate registered with hvc_instantiate(). |
82 | */ |
83 | static int last_hvc = -1; |
84 | |
85 | /* |
86 | * Do not call this function with either the hvc_structs_mutex or the hvc_struct |
87 | * lock held. If successful, this function increments the kref reference |
88 | * count against the target hvc_struct so it should be released when finished. |
89 | */ |
90 | static struct hvc_struct *hvc_get_by_index(int index) |
91 | { |
92 | struct hvc_struct *hp; |
93 | unsigned long flags; |
94 | |
95 | mutex_lock(&hvc_structs_mutex); |
96 | |
97 | list_for_each_entry(hp, &hvc_structs, next) { |
98 | spin_lock_irqsave(&hp->lock, flags); |
99 | if (hp->index == index) { |
100 | tty_port_get(port: &hp->port); |
101 | spin_unlock_irqrestore(lock: &hp->lock, flags); |
102 | mutex_unlock(lock: &hvc_structs_mutex); |
103 | return hp; |
104 | } |
105 | spin_unlock_irqrestore(lock: &hp->lock, flags); |
106 | } |
107 | hp = NULL; |
108 | mutex_unlock(lock: &hvc_structs_mutex); |
109 | |
110 | return hp; |
111 | } |
112 | |
113 | static int __hvc_flush(const struct hv_ops *ops, uint32_t vtermno, bool wait) |
114 | { |
115 | if (wait) |
116 | might_sleep(); |
117 | |
118 | if (ops->flush) |
119 | return ops->flush(vtermno, wait); |
120 | return 0; |
121 | } |
122 | |
123 | static int hvc_console_flush(const struct hv_ops *ops, uint32_t vtermno) |
124 | { |
125 | return __hvc_flush(ops, vtermno, wait: false); |
126 | } |
127 | |
128 | /* |
129 | * Wait for the console to flush before writing more to it. This sleeps. |
130 | */ |
131 | static int hvc_flush(struct hvc_struct *hp) |
132 | { |
133 | return __hvc_flush(ops: hp->ops, vtermno: hp->vtermno, wait: true); |
134 | } |
135 | |
136 | /* |
137 | * Initial console vtermnos for console API usage prior to full console |
138 | * initialization. Any vty adapter outside this range will not have usable |
139 | * console interfaces but can still be used as a tty device. This has to be |
140 | * static because kmalloc will not work during early console init. |
141 | */ |
142 | static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES]; |
143 | static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] = |
144 | {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1}; |
145 | |
146 | /* |
147 | * Console APIs, NOT TTY. These APIs are available immediately when |
148 | * hvc_console_setup() finds adapters. |
149 | */ |
150 | |
151 | static void hvc_console_print(struct console *co, const char *b, |
152 | unsigned count) |
153 | { |
154 | char c[N_OUTBUF] __ALIGNED__; |
155 | unsigned i = 0, n = 0; |
156 | int r, donecr = 0, index = co->index; |
157 | |
158 | /* Console access attempt outside of acceptable console range. */ |
159 | if (index >= MAX_NR_HVC_CONSOLES) |
160 | return; |
161 | |
162 | /* This console adapter was removed so it is not usable. */ |
163 | if (vtermnos[index] == -1) |
164 | return; |
165 | |
166 | while (count > 0 || i > 0) { |
167 | if (count > 0 && i < sizeof(c)) { |
168 | if (b[n] == '\n' && !donecr) { |
169 | c[i++] = '\r'; |
170 | donecr = 1; |
171 | } else { |
172 | c[i++] = b[n++]; |
173 | donecr = 0; |
174 | --count; |
175 | } |
176 | } else { |
177 | r = cons_ops[index]->put_chars(vtermnos[index], c, i); |
178 | if (r <= 0) { |
179 | /* throw away characters on error |
180 | * but spin in case of -EAGAIN */ |
181 | if (r != -EAGAIN) { |
182 | i = 0; |
183 | } else { |
184 | hvc_console_flush(ops: cons_ops[index], |
185 | vtermno: vtermnos[index]); |
186 | } |
187 | } else if (r > 0) { |
188 | i -= r; |
189 | if (i > 0) |
190 | memmove(c, c+r, i); |
191 | } |
192 | } |
193 | } |
194 | hvc_console_flush(ops: cons_ops[index], vtermno: vtermnos[index]); |
195 | } |
196 | |
197 | static struct tty_driver *hvc_console_device(struct console *c, int *index) |
198 | { |
199 | if (vtermnos[c->index] == -1) |
200 | return NULL; |
201 | |
202 | *index = c->index; |
203 | return hvc_driver; |
204 | } |
205 | |
206 | static int hvc_console_setup(struct console *co, char *options) |
207 | { |
208 | if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES) |
209 | return -ENODEV; |
210 | |
211 | if (vtermnos[co->index] == -1) |
212 | return -ENODEV; |
213 | |
214 | return 0; |
215 | } |
216 | |
217 | static struct console hvc_console = { |
218 | .name = "hvc" , |
219 | .write = hvc_console_print, |
220 | .device = hvc_console_device, |
221 | .setup = hvc_console_setup, |
222 | .flags = CON_PRINTBUFFER, |
223 | .index = -1, |
224 | }; |
225 | |
226 | /* |
227 | * Early console initialization. Precedes driver initialization. |
228 | * |
229 | * (1) we are first, and the user specified another driver |
230 | * -- index will remain -1 |
231 | * (2) we are first and the user specified no driver |
232 | * -- index will be set to 0, then we will fail setup. |
233 | * (3) we are first and the user specified our driver |
234 | * -- index will be set to user specified driver, and we will fail |
235 | * (4) we are after driver, and this initcall will register us |
236 | * -- if the user didn't specify a driver then the console will match |
237 | * |
238 | * Note that for cases 2 and 3, we will match later when the io driver |
239 | * calls hvc_instantiate() and call register again. |
240 | */ |
241 | static int __init hvc_console_init(void) |
242 | { |
243 | register_console(&hvc_console); |
244 | return 0; |
245 | } |
246 | console_initcall(hvc_console_init); |
247 | |
248 | /* callback when the kboject ref count reaches zero. */ |
249 | static void hvc_port_destruct(struct tty_port *port) |
250 | { |
251 | struct hvc_struct *hp = container_of(port, struct hvc_struct, port); |
252 | unsigned long flags; |
253 | |
254 | mutex_lock(&hvc_structs_mutex); |
255 | |
256 | spin_lock_irqsave(&hp->lock, flags); |
257 | list_del(entry: &(hp->next)); |
258 | spin_unlock_irqrestore(lock: &hp->lock, flags); |
259 | |
260 | mutex_unlock(lock: &hvc_structs_mutex); |
261 | |
262 | kfree(objp: hp); |
263 | } |
264 | |
265 | static void hvc_check_console(int index) |
266 | { |
267 | /* Already registered, bail out */ |
268 | if (console_is_registered(con: &hvc_console)) |
269 | return; |
270 | |
271 | /* If this index is what the user requested, then register |
272 | * now (setup won't fail at this point). It's ok to just |
273 | * call register again if previously .setup failed. |
274 | */ |
275 | if (index == hvc_console.index) |
276 | register_console(&hvc_console); |
277 | } |
278 | |
279 | /* |
280 | * hvc_instantiate() is an early console discovery method which locates |
281 | * consoles * prior to the vio subsystem discovering them. Hotplugged |
282 | * vty adapters do NOT get an hvc_instantiate() callback since they |
283 | * appear after early console init. |
284 | */ |
285 | int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops) |
286 | { |
287 | struct hvc_struct *hp; |
288 | |
289 | if (index < 0 || index >= MAX_NR_HVC_CONSOLES) |
290 | return -1; |
291 | |
292 | if (vtermnos[index] != -1) |
293 | return -1; |
294 | |
295 | /* make sure no tty has been registered in this index */ |
296 | hp = hvc_get_by_index(index); |
297 | if (hp) { |
298 | tty_port_put(port: &hp->port); |
299 | return -1; |
300 | } |
301 | |
302 | vtermnos[index] = vtermno; |
303 | cons_ops[index] = ops; |
304 | |
305 | /* check if we need to re-register the kernel console */ |
306 | hvc_check_console(index); |
307 | |
308 | return 0; |
309 | } |
310 | EXPORT_SYMBOL_GPL(hvc_instantiate); |
311 | |
312 | /* Wake the sleeping khvcd */ |
313 | void hvc_kick(void) |
314 | { |
315 | hvc_kicked = 1; |
316 | wake_up_process(tsk: hvc_task); |
317 | } |
318 | EXPORT_SYMBOL_GPL(hvc_kick); |
319 | |
320 | static void hvc_unthrottle(struct tty_struct *tty) |
321 | { |
322 | hvc_kick(); |
323 | } |
324 | |
325 | static int hvc_install(struct tty_driver *driver, struct tty_struct *tty) |
326 | { |
327 | struct hvc_struct *hp; |
328 | int rc; |
329 | |
330 | /* Auto increments kref reference if found. */ |
331 | hp = hvc_get_by_index(index: tty->index); |
332 | if (!hp) |
333 | return -ENODEV; |
334 | |
335 | tty->driver_data = hp; |
336 | |
337 | rc = tty_port_install(port: &hp->port, driver, tty); |
338 | if (rc) |
339 | tty_port_put(port: &hp->port); |
340 | return rc; |
341 | } |
342 | |
343 | /* |
344 | * The TTY interface won't be used until after the vio layer has exposed the vty |
345 | * adapter to the kernel. |
346 | */ |
347 | static int hvc_open(struct tty_struct *tty, struct file * filp) |
348 | { |
349 | struct hvc_struct *hp = tty->driver_data; |
350 | unsigned long flags; |
351 | int rc = 0; |
352 | |
353 | spin_lock_irqsave(&hp->port.lock, flags); |
354 | /* Check and then increment for fast path open. */ |
355 | if (hp->port.count++ > 0) { |
356 | spin_unlock_irqrestore(lock: &hp->port.lock, flags); |
357 | hvc_kick(); |
358 | return 0; |
359 | } /* else count == 0 */ |
360 | spin_unlock_irqrestore(lock: &hp->port.lock, flags); |
361 | |
362 | tty_port_tty_set(port: &hp->port, tty); |
363 | |
364 | if (hp->ops->notifier_add) |
365 | rc = hp->ops->notifier_add(hp, hp->data); |
366 | |
367 | /* |
368 | * If the notifier fails we return an error. The tty layer |
369 | * will call hvc_close() after a failed open but we don't want to clean |
370 | * up there so we'll clean up here and clear out the previously set |
371 | * tty fields and return the kref reference. |
372 | */ |
373 | if (rc) { |
374 | printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n" , rc); |
375 | } else { |
376 | /* We are ready... raise DTR/RTS */ |
377 | if (C_BAUD(tty)) |
378 | if (hp->ops->dtr_rts) |
379 | hp->ops->dtr_rts(hp, true); |
380 | tty_port_set_initialized(port: &hp->port, val: true); |
381 | } |
382 | |
383 | /* Force wakeup of the polling thread */ |
384 | hvc_kick(); |
385 | |
386 | return rc; |
387 | } |
388 | |
389 | static void hvc_close(struct tty_struct *tty, struct file * filp) |
390 | { |
391 | struct hvc_struct *hp = tty->driver_data; |
392 | unsigned long flags; |
393 | |
394 | if (tty_hung_up_p(filp)) |
395 | return; |
396 | |
397 | spin_lock_irqsave(&hp->port.lock, flags); |
398 | |
399 | if (--hp->port.count == 0) { |
400 | spin_unlock_irqrestore(lock: &hp->port.lock, flags); |
401 | /* We are done with the tty pointer now. */ |
402 | tty_port_tty_set(port: &hp->port, NULL); |
403 | |
404 | if (!tty_port_initialized(port: &hp->port)) |
405 | return; |
406 | |
407 | if (C_HUPCL(tty)) |
408 | if (hp->ops->dtr_rts) |
409 | hp->ops->dtr_rts(hp, false); |
410 | |
411 | if (hp->ops->notifier_del) |
412 | hp->ops->notifier_del(hp, hp->data); |
413 | |
414 | /* cancel pending tty resize work */ |
415 | cancel_work_sync(work: &hp->tty_resize); |
416 | |
417 | /* |
418 | * Chain calls chars_in_buffer() and returns immediately if |
419 | * there is no buffered data otherwise sleeps on a wait queue |
420 | * waking periodically to check chars_in_buffer(). |
421 | */ |
422 | tty_wait_until_sent(tty, HVC_CLOSE_WAIT); |
423 | tty_port_set_initialized(port: &hp->port, val: false); |
424 | } else { |
425 | if (hp->port.count < 0) |
426 | printk(KERN_ERR "hvc_close %X: oops, count is %d\n" , |
427 | hp->vtermno, hp->port.count); |
428 | spin_unlock_irqrestore(lock: &hp->port.lock, flags); |
429 | } |
430 | } |
431 | |
432 | static void hvc_cleanup(struct tty_struct *tty) |
433 | { |
434 | struct hvc_struct *hp = tty->driver_data; |
435 | |
436 | tty_port_put(port: &hp->port); |
437 | } |
438 | |
439 | static void hvc_hangup(struct tty_struct *tty) |
440 | { |
441 | struct hvc_struct *hp = tty->driver_data; |
442 | unsigned long flags; |
443 | |
444 | if (!hp) |
445 | return; |
446 | |
447 | /* cancel pending tty resize work */ |
448 | cancel_work_sync(work: &hp->tty_resize); |
449 | |
450 | spin_lock_irqsave(&hp->port.lock, flags); |
451 | |
452 | /* |
453 | * The N_TTY line discipline has problems such that in a close vs |
454 | * open->hangup case this can be called after the final close so prevent |
455 | * that from happening for now. |
456 | */ |
457 | if (hp->port.count <= 0) { |
458 | spin_unlock_irqrestore(lock: &hp->port.lock, flags); |
459 | return; |
460 | } |
461 | |
462 | hp->port.count = 0; |
463 | spin_unlock_irqrestore(lock: &hp->port.lock, flags); |
464 | tty_port_tty_set(port: &hp->port, NULL); |
465 | |
466 | hp->n_outbuf = 0; |
467 | |
468 | if (hp->ops->notifier_hangup) |
469 | hp->ops->notifier_hangup(hp, hp->data); |
470 | } |
471 | |
472 | /* |
473 | * Push buffered characters whether they were just recently buffered or waiting |
474 | * on a blocked hypervisor. Call this function with hp->lock held. |
475 | */ |
476 | static int hvc_push(struct hvc_struct *hp) |
477 | { |
478 | int n; |
479 | |
480 | n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf); |
481 | if (n <= 0) { |
482 | if (n == 0 || n == -EAGAIN) { |
483 | hp->do_wakeup = 1; |
484 | return 0; |
485 | } |
486 | /* throw away output on error; this happens when |
487 | there is no session connected to the vterm. */ |
488 | hp->n_outbuf = 0; |
489 | } else |
490 | hp->n_outbuf -= n; |
491 | if (hp->n_outbuf > 0) |
492 | memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf); |
493 | else |
494 | hp->do_wakeup = 1; |
495 | |
496 | return n; |
497 | } |
498 | |
499 | static ssize_t hvc_write(struct tty_struct *tty, const u8 *buf, size_t count) |
500 | { |
501 | struct hvc_struct *hp = tty->driver_data; |
502 | unsigned long flags; |
503 | size_t rsize, written = 0; |
504 | |
505 | /* This write was probably executed during a tty close. */ |
506 | if (!hp) |
507 | return -EPIPE; |
508 | |
509 | /* FIXME what's this (unprotected) check for? */ |
510 | if (hp->port.count <= 0) |
511 | return -EIO; |
512 | |
513 | while (count > 0) { |
514 | int ret = 0; |
515 | |
516 | spin_lock_irqsave(&hp->lock, flags); |
517 | |
518 | rsize = hp->outbuf_size - hp->n_outbuf; |
519 | |
520 | if (rsize) { |
521 | if (rsize > count) |
522 | rsize = count; |
523 | memcpy(hp->outbuf + hp->n_outbuf, buf, rsize); |
524 | count -= rsize; |
525 | buf += rsize; |
526 | hp->n_outbuf += rsize; |
527 | written += rsize; |
528 | } |
529 | |
530 | if (hp->n_outbuf > 0) |
531 | ret = hvc_push(hp); |
532 | |
533 | spin_unlock_irqrestore(lock: &hp->lock, flags); |
534 | |
535 | if (!ret) |
536 | break; |
537 | |
538 | if (count) { |
539 | if (hp->n_outbuf > 0) |
540 | hvc_flush(hp); |
541 | cond_resched(); |
542 | } |
543 | } |
544 | |
545 | /* |
546 | * Racy, but harmless, kick thread if there is still pending data. |
547 | */ |
548 | if (hp->n_outbuf) |
549 | hvc_kick(); |
550 | |
551 | return written; |
552 | } |
553 | |
554 | /** |
555 | * hvc_set_winsz() - Resize the hvc tty terminal window. |
556 | * @work: work structure. |
557 | * |
558 | * The routine shall not be called within an atomic context because it |
559 | * might sleep. |
560 | * |
561 | * Locking: hp->lock |
562 | */ |
563 | static void hvc_set_winsz(struct work_struct *work) |
564 | { |
565 | struct hvc_struct *hp; |
566 | unsigned long hvc_flags; |
567 | struct tty_struct *tty; |
568 | struct winsize ws; |
569 | |
570 | hp = container_of(work, struct hvc_struct, tty_resize); |
571 | |
572 | tty = tty_port_tty_get(port: &hp->port); |
573 | if (!tty) |
574 | return; |
575 | |
576 | spin_lock_irqsave(&hp->lock, hvc_flags); |
577 | ws = hp->ws; |
578 | spin_unlock_irqrestore(lock: &hp->lock, flags: hvc_flags); |
579 | |
580 | tty_do_resize(tty, ws: &ws); |
581 | tty_kref_put(tty); |
582 | } |
583 | |
584 | /* |
585 | * This is actually a contract between the driver and the tty layer outlining |
586 | * how much write room the driver can guarantee will be sent OR BUFFERED. This |
587 | * driver MUST honor the return value. |
588 | */ |
589 | static unsigned int hvc_write_room(struct tty_struct *tty) |
590 | { |
591 | struct hvc_struct *hp = tty->driver_data; |
592 | |
593 | if (!hp) |
594 | return 0; |
595 | |
596 | return hp->outbuf_size - hp->n_outbuf; |
597 | } |
598 | |
599 | static unsigned int hvc_chars_in_buffer(struct tty_struct *tty) |
600 | { |
601 | struct hvc_struct *hp = tty->driver_data; |
602 | |
603 | if (!hp) |
604 | return 0; |
605 | return hp->n_outbuf; |
606 | } |
607 | |
608 | /* |
609 | * timeout will vary between the MIN and MAX values defined here. By default |
610 | * and during console activity we will use a default MIN_TIMEOUT of 10. When |
611 | * the console is idle, we increase the timeout value on each pass through |
612 | * msleep until we reach the max. This may be noticeable as a brief (average |
613 | * one second) delay on the console before the console responds to input when |
614 | * there has been no input for some time. |
615 | */ |
616 | #define MIN_TIMEOUT (10) |
617 | #define MAX_TIMEOUT (2000) |
618 | static u32 timeout = MIN_TIMEOUT; |
619 | |
620 | /* |
621 | * Maximum number of bytes to get from the console driver if hvc_poll is |
622 | * called from driver (and can't sleep). Any more than this and we break |
623 | * and start polling with khvcd. This value was derived from an OpenBMC |
624 | * console with the OPAL driver that results in about 0.25ms interrupts off |
625 | * latency. |
626 | */ |
627 | #define HVC_ATOMIC_READ_MAX 128 |
628 | |
629 | #define HVC_POLL_READ 0x00000001 |
630 | #define HVC_POLL_WRITE 0x00000002 |
631 | |
632 | static int __hvc_poll(struct hvc_struct *hp, bool may_sleep) |
633 | { |
634 | struct tty_struct *tty; |
635 | int i, n, count, poll_mask = 0; |
636 | char buf[N_INBUF] __ALIGNED__; |
637 | unsigned long flags; |
638 | int read_total = 0; |
639 | int written_total = 0; |
640 | |
641 | spin_lock_irqsave(&hp->lock, flags); |
642 | |
643 | /* Push pending writes */ |
644 | if (hp->n_outbuf > 0) |
645 | written_total = hvc_push(hp); |
646 | |
647 | /* Reschedule us if still some write pending */ |
648 | if (hp->n_outbuf > 0) { |
649 | poll_mask |= HVC_POLL_WRITE; |
650 | /* If hvc_push() was not able to write, sleep a few msecs */ |
651 | timeout = (written_total) ? 0 : MIN_TIMEOUT; |
652 | } |
653 | |
654 | if (may_sleep) { |
655 | spin_unlock_irqrestore(lock: &hp->lock, flags); |
656 | cond_resched(); |
657 | spin_lock_irqsave(&hp->lock, flags); |
658 | } |
659 | |
660 | /* No tty attached, just skip */ |
661 | tty = tty_port_tty_get(port: &hp->port); |
662 | if (tty == NULL) |
663 | goto bail; |
664 | |
665 | /* Now check if we can get data (are we throttled ?) */ |
666 | if (tty_throttled(tty)) |
667 | goto out; |
668 | |
669 | /* If we aren't notifier driven and aren't throttled, we always |
670 | * request a reschedule |
671 | */ |
672 | if (!hp->irq_requested) |
673 | poll_mask |= HVC_POLL_READ; |
674 | |
675 | read_again: |
676 | /* Read data if any */ |
677 | count = tty_buffer_request_room(port: &hp->port, N_INBUF); |
678 | |
679 | /* If flip is full, just reschedule a later read */ |
680 | if (count == 0) { |
681 | poll_mask |= HVC_POLL_READ; |
682 | goto out; |
683 | } |
684 | |
685 | n = hp->ops->get_chars(hp->vtermno, buf, count); |
686 | if (n <= 0) { |
687 | /* Hangup the tty when disconnected from host */ |
688 | if (n == -EPIPE) { |
689 | spin_unlock_irqrestore(lock: &hp->lock, flags); |
690 | tty_hangup(tty); |
691 | spin_lock_irqsave(&hp->lock, flags); |
692 | } else if ( n == -EAGAIN ) { |
693 | /* |
694 | * Some back-ends can only ensure a certain min |
695 | * num of bytes read, which may be > 'count'. |
696 | * Let the tty clear the flip buff to make room. |
697 | */ |
698 | poll_mask |= HVC_POLL_READ; |
699 | } |
700 | goto out; |
701 | } |
702 | |
703 | for (i = 0; i < n; ++i) { |
704 | #ifdef CONFIG_MAGIC_SYSRQ |
705 | if (hp->index == hvc_console.index) { |
706 | /* Handle the SysRq Hack */ |
707 | /* XXX should support a sequence */ |
708 | if (buf[i] == '\x0f') { /* ^O */ |
709 | /* if ^O is pressed again, reset |
710 | * sysrq_pressed and flip ^O char */ |
711 | sysrq_pressed = !sysrq_pressed; |
712 | if (sysrq_pressed) |
713 | continue; |
714 | } else if (sysrq_pressed) { |
715 | handle_sysrq(key: buf[i]); |
716 | sysrq_pressed = 0; |
717 | continue; |
718 | } |
719 | } |
720 | #endif /* CONFIG_MAGIC_SYSRQ */ |
721 | tty_insert_flip_char(port: &hp->port, ch: buf[i], flag: 0); |
722 | } |
723 | read_total += n; |
724 | |
725 | if (may_sleep) { |
726 | /* Keep going until the flip is full */ |
727 | spin_unlock_irqrestore(lock: &hp->lock, flags); |
728 | cond_resched(); |
729 | spin_lock_irqsave(&hp->lock, flags); |
730 | goto read_again; |
731 | } else if (read_total < HVC_ATOMIC_READ_MAX) { |
732 | /* Break and defer if it's a large read in atomic */ |
733 | goto read_again; |
734 | } |
735 | |
736 | /* |
737 | * Latency break, schedule another poll immediately. |
738 | */ |
739 | poll_mask |= HVC_POLL_READ; |
740 | |
741 | out: |
742 | /* Wakeup write queue if necessary */ |
743 | if (hp->do_wakeup) { |
744 | hp->do_wakeup = 0; |
745 | tty_wakeup(tty); |
746 | } |
747 | bail: |
748 | spin_unlock_irqrestore(lock: &hp->lock, flags); |
749 | |
750 | if (read_total) { |
751 | /* Activity is occurring, so reset the polling backoff value to |
752 | a minimum for performance. */ |
753 | timeout = MIN_TIMEOUT; |
754 | |
755 | tty_flip_buffer_push(port: &hp->port); |
756 | } |
757 | tty_kref_put(tty); |
758 | |
759 | return poll_mask; |
760 | } |
761 | |
762 | int hvc_poll(struct hvc_struct *hp) |
763 | { |
764 | return __hvc_poll(hp, may_sleep: false); |
765 | } |
766 | EXPORT_SYMBOL_GPL(hvc_poll); |
767 | |
768 | /** |
769 | * __hvc_resize() - Update terminal window size information. |
770 | * @hp: HVC console pointer |
771 | * @ws: Terminal window size structure |
772 | * |
773 | * Stores the specified window size information in the hvc structure of @hp. |
774 | * The function schedule the tty resize update. |
775 | * |
776 | * Locking: Locking free; the function MUST be called holding hp->lock |
777 | */ |
778 | void __hvc_resize(struct hvc_struct *hp, struct winsize ws) |
779 | { |
780 | hp->ws = ws; |
781 | schedule_work(work: &hp->tty_resize); |
782 | } |
783 | EXPORT_SYMBOL_GPL(__hvc_resize); |
784 | |
785 | /* |
786 | * This kthread is either polling or interrupt driven. This is determined by |
787 | * calling hvc_poll() who determines whether a console adapter support |
788 | * interrupts. |
789 | */ |
790 | static int khvcd(void *unused) |
791 | { |
792 | int poll_mask; |
793 | struct hvc_struct *hp; |
794 | |
795 | set_freezable(); |
796 | do { |
797 | poll_mask = 0; |
798 | hvc_kicked = 0; |
799 | try_to_freeze(); |
800 | wmb(); |
801 | if (!cpus_are_in_xmon()) { |
802 | mutex_lock(&hvc_structs_mutex); |
803 | list_for_each_entry(hp, &hvc_structs, next) { |
804 | poll_mask |= __hvc_poll(hp, may_sleep: true); |
805 | cond_resched(); |
806 | } |
807 | mutex_unlock(lock: &hvc_structs_mutex); |
808 | } else |
809 | poll_mask |= HVC_POLL_READ; |
810 | if (hvc_kicked) |
811 | continue; |
812 | set_current_state(TASK_INTERRUPTIBLE); |
813 | if (!hvc_kicked) { |
814 | if (poll_mask == 0) |
815 | schedule(); |
816 | else { |
817 | unsigned long j_timeout; |
818 | |
819 | if (timeout < MAX_TIMEOUT) |
820 | timeout += (timeout >> 6) + 1; |
821 | |
822 | /* |
823 | * We don't use msleep_interruptible otherwise |
824 | * "kick" will fail to wake us up |
825 | */ |
826 | j_timeout = msecs_to_jiffies(m: timeout) + 1; |
827 | schedule_timeout_interruptible(timeout: j_timeout); |
828 | } |
829 | } |
830 | __set_current_state(TASK_RUNNING); |
831 | } while (!kthread_should_stop()); |
832 | |
833 | return 0; |
834 | } |
835 | |
836 | static int hvc_tiocmget(struct tty_struct *tty) |
837 | { |
838 | struct hvc_struct *hp = tty->driver_data; |
839 | |
840 | if (!hp || !hp->ops->tiocmget) |
841 | return -EINVAL; |
842 | return hp->ops->tiocmget(hp); |
843 | } |
844 | |
845 | static int hvc_tiocmset(struct tty_struct *tty, |
846 | unsigned int set, unsigned int clear) |
847 | { |
848 | struct hvc_struct *hp = tty->driver_data; |
849 | |
850 | if (!hp || !hp->ops->tiocmset) |
851 | return -EINVAL; |
852 | return hp->ops->tiocmset(hp, set, clear); |
853 | } |
854 | |
855 | #ifdef CONFIG_CONSOLE_POLL |
856 | static int hvc_poll_init(struct tty_driver *driver, int line, char *options) |
857 | { |
858 | return 0; |
859 | } |
860 | |
861 | static int hvc_poll_get_char(struct tty_driver *driver, int line) |
862 | { |
863 | struct tty_struct *tty = driver->ttys[0]; |
864 | struct hvc_struct *hp = tty->driver_data; |
865 | int n; |
866 | char ch; |
867 | |
868 | n = hp->ops->get_chars(hp->vtermno, &ch, 1); |
869 | |
870 | if (n <= 0) |
871 | return NO_POLL_CHAR; |
872 | |
873 | return ch; |
874 | } |
875 | |
876 | static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch) |
877 | { |
878 | struct tty_struct *tty = driver->ttys[0]; |
879 | struct hvc_struct *hp = tty->driver_data; |
880 | int n; |
881 | |
882 | do { |
883 | n = hp->ops->put_chars(hp->vtermno, &ch, 1); |
884 | } while (n <= 0); |
885 | } |
886 | #endif |
887 | |
888 | static const struct tty_operations hvc_ops = { |
889 | .install = hvc_install, |
890 | .open = hvc_open, |
891 | .close = hvc_close, |
892 | .cleanup = hvc_cleanup, |
893 | .write = hvc_write, |
894 | .hangup = hvc_hangup, |
895 | .unthrottle = hvc_unthrottle, |
896 | .write_room = hvc_write_room, |
897 | .chars_in_buffer = hvc_chars_in_buffer, |
898 | .tiocmget = hvc_tiocmget, |
899 | .tiocmset = hvc_tiocmset, |
900 | #ifdef CONFIG_CONSOLE_POLL |
901 | .poll_init = hvc_poll_init, |
902 | .poll_get_char = hvc_poll_get_char, |
903 | .poll_put_char = hvc_poll_put_char, |
904 | #endif |
905 | }; |
906 | |
907 | static const struct tty_port_operations hvc_port_ops = { |
908 | .destruct = hvc_port_destruct, |
909 | }; |
910 | |
911 | struct hvc_struct *hvc_alloc(uint32_t vtermno, int data, |
912 | const struct hv_ops *ops, |
913 | int outbuf_size) |
914 | { |
915 | struct hvc_struct *hp; |
916 | int i; |
917 | |
918 | /* We wait until a driver actually comes along */ |
919 | if (atomic_inc_not_zero(v: &hvc_needs_init)) { |
920 | int err = hvc_init(); |
921 | if (err) |
922 | return ERR_PTR(error: err); |
923 | } |
924 | |
925 | hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size, |
926 | GFP_KERNEL); |
927 | if (!hp) |
928 | return ERR_PTR(error: -ENOMEM); |
929 | |
930 | hp->vtermno = vtermno; |
931 | hp->data = data; |
932 | hp->ops = ops; |
933 | hp->outbuf_size = outbuf_size; |
934 | hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))]; |
935 | |
936 | tty_port_init(port: &hp->port); |
937 | hp->port.ops = &hvc_port_ops; |
938 | |
939 | INIT_WORK(&hp->tty_resize, hvc_set_winsz); |
940 | spin_lock_init(&hp->lock); |
941 | mutex_lock(&hvc_structs_mutex); |
942 | |
943 | /* |
944 | * find index to use: |
945 | * see if this vterm id matches one registered for console. |
946 | */ |
947 | for (i=0; i < MAX_NR_HVC_CONSOLES; i++) |
948 | if (vtermnos[i] == hp->vtermno && |
949 | cons_ops[i] == hp->ops) |
950 | break; |
951 | |
952 | if (i >= MAX_NR_HVC_CONSOLES) { |
953 | |
954 | /* find 'empty' slot for console */ |
955 | for (i = 0; i < MAX_NR_HVC_CONSOLES && vtermnos[i] != -1; i++) { |
956 | } |
957 | |
958 | /* no matching slot, just use a counter */ |
959 | if (i == MAX_NR_HVC_CONSOLES) |
960 | i = ++last_hvc + MAX_NR_HVC_CONSOLES; |
961 | } |
962 | |
963 | hp->index = i; |
964 | if (i < MAX_NR_HVC_CONSOLES) { |
965 | cons_ops[i] = ops; |
966 | vtermnos[i] = vtermno; |
967 | } |
968 | |
969 | list_add_tail(new: &(hp->next), head: &hvc_structs); |
970 | mutex_unlock(lock: &hvc_structs_mutex); |
971 | |
972 | /* check if we need to re-register the kernel console */ |
973 | hvc_check_console(index: i); |
974 | |
975 | return hp; |
976 | } |
977 | EXPORT_SYMBOL_GPL(hvc_alloc); |
978 | |
979 | int hvc_remove(struct hvc_struct *hp) |
980 | { |
981 | unsigned long flags; |
982 | struct tty_struct *tty; |
983 | |
984 | tty = tty_port_tty_get(port: &hp->port); |
985 | |
986 | console_lock(); |
987 | spin_lock_irqsave(&hp->lock, flags); |
988 | if (hp->index < MAX_NR_HVC_CONSOLES) { |
989 | vtermnos[hp->index] = -1; |
990 | cons_ops[hp->index] = NULL; |
991 | } |
992 | |
993 | /* Don't whack hp->irq because tty_hangup() will need to free the irq. */ |
994 | |
995 | spin_unlock_irqrestore(lock: &hp->lock, flags); |
996 | console_unlock(); |
997 | |
998 | /* |
999 | * We 'put' the instance that was grabbed when the kref instance |
1000 | * was initialized using kref_init(). Let the last holder of this |
1001 | * kref cause it to be removed, which will probably be the tty_vhangup |
1002 | * below. |
1003 | */ |
1004 | tty_port_put(port: &hp->port); |
1005 | |
1006 | /* |
1007 | * This function call will auto chain call hvc_hangup. |
1008 | */ |
1009 | if (tty) { |
1010 | tty_vhangup(tty); |
1011 | tty_kref_put(tty); |
1012 | } |
1013 | return 0; |
1014 | } |
1015 | EXPORT_SYMBOL_GPL(hvc_remove); |
1016 | |
1017 | /* Driver initialization: called as soon as someone uses hvc_alloc(). */ |
1018 | static int hvc_init(void) |
1019 | { |
1020 | struct tty_driver *drv; |
1021 | int err; |
1022 | |
1023 | /* We need more than hvc_count adapters due to hotplug additions. */ |
1024 | drv = tty_alloc_driver(HVC_ALLOC_TTY_ADAPTERS, TTY_DRIVER_REAL_RAW | |
1025 | TTY_DRIVER_RESET_TERMIOS); |
1026 | if (IS_ERR(ptr: drv)) { |
1027 | err = PTR_ERR(ptr: drv); |
1028 | goto out; |
1029 | } |
1030 | |
1031 | drv->driver_name = "hvc" ; |
1032 | drv->name = "hvc" ; |
1033 | drv->major = HVC_MAJOR; |
1034 | drv->minor_start = HVC_MINOR; |
1035 | drv->type = TTY_DRIVER_TYPE_SYSTEM; |
1036 | drv->init_termios = tty_std_termios; |
1037 | tty_set_operations(driver: drv, op: &hvc_ops); |
1038 | |
1039 | /* Always start the kthread because there can be hotplug vty adapters |
1040 | * added later. */ |
1041 | hvc_task = kthread_run(khvcd, NULL, "khvcd" ); |
1042 | if (IS_ERR(ptr: hvc_task)) { |
1043 | printk(KERN_ERR "Couldn't create kthread for console.\n" ); |
1044 | err = PTR_ERR(ptr: hvc_task); |
1045 | goto put_tty; |
1046 | } |
1047 | |
1048 | err = tty_register_driver(driver: drv); |
1049 | if (err) { |
1050 | printk(KERN_ERR "Couldn't register hvc console driver\n" ); |
1051 | goto stop_thread; |
1052 | } |
1053 | |
1054 | /* |
1055 | * Make sure tty is fully registered before allowing it to be |
1056 | * found by hvc_console_device. |
1057 | */ |
1058 | smp_mb(); |
1059 | hvc_driver = drv; |
1060 | return 0; |
1061 | |
1062 | stop_thread: |
1063 | kthread_stop(k: hvc_task); |
1064 | hvc_task = NULL; |
1065 | put_tty: |
1066 | tty_driver_kref_put(driver: drv); |
1067 | out: |
1068 | return err; |
1069 | } |
1070 | |