2 * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
3 * Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM
4 * Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
5 * Copyright (C) 2004 IBM Corporation
7 * Additional Author(s):
8 * Ryan S. Arnold <rsa@us.ibm.com>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
25 #include <linux/console.h>
26 #include <linux/cpumask.h>
27 #include <linux/init.h>
28 #include <linux/kbd_kern.h>
29 #include <linux/kernel.h>
30 #include <linux/kthread.h>
31 #include <linux/list.h>
32 #include <linux/module.h>
33 #include <linux/major.h>
34 #include <linux/sysrq.h>
35 #include <linux/tty.h>
36 #include <linux/tty_flip.h>
37 #include <linux/sched.h>
38 #include <linux/spinlock.h>
39 #include <linux/delay.h>
40 #include <linux/freezer.h>
41 #include <linux/slab.h>
42 #include <linux/serial_core.h>
44 #include <asm/uaccess.h>
46 #include "hvc_console.h"
52 * Wait this long per iteration while trying to push buffered data to the
53 * hypervisor before allowing the tty to complete a close operation.
55 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
58 * These sizes are most efficient for vio, because they are the
59 * native transfer size. We could make them selectable in the
60 * future to better deal with backends that want other buffer sizes.
65 #define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
67 static struct tty_driver *hvc_driver;
68 static struct task_struct *hvc_task;
70 /* Picks up late kicks after list walk but before schedule() */
71 static int hvc_kicked;
73 static int hvc_init(void);
75 #ifdef CONFIG_MAGIC_SYSRQ
76 static int sysrq_pressed;
79 /* dynamic list of hvc_struct instances */
80 static LIST_HEAD(hvc_structs);
83 * Protect the list of hvc_struct instances from inserts and removals during
86 static DEFINE_SPINLOCK(hvc_structs_lock);
89 * This value is used to assign a tty->index value to a hvc_struct based
90 * upon order of exposure via hvc_probe(), when we can not match it to
91 * a console candidate registered with hvc_instantiate().
93 static int last_hvc = -1;
96 * Do not call this function with either the hvc_structs_lock or the hvc_struct
97 * lock held. If successful, this function increments the kref reference
98 * count against the target hvc_struct so it should be released when finished.
100 static struct hvc_struct *hvc_get_by_index(int index)
102 struct hvc_struct *hp;
105 spin_lock(&hvc_structs_lock);
107 list_for_each_entry(hp, &hvc_structs, next) {
108 spin_lock_irqsave(&hp->lock, flags);
109 if (hp->index == index) {
110 tty_port_get(&hp->port);
111 spin_unlock_irqrestore(&hp->lock, flags);
112 spin_unlock(&hvc_structs_lock);
115 spin_unlock_irqrestore(&hp->lock, flags);
119 spin_unlock(&hvc_structs_lock);
125 * Initial console vtermnos for console API usage prior to full console
126 * initialization. Any vty adapter outside this range will not have usable
127 * console interfaces but can still be used as a tty device. This has to be
128 * static because kmalloc will not work during early console init.
130 static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
131 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
132 {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
135 * Console APIs, NOT TTY. These APIs are available immediately when
136 * hvc_console_setup() finds adapters.
139 static void hvc_console_print(struct console *co, const char *b,
142 char c[N_OUTBUF] __ALIGNED__;
143 unsigned i = 0, n = 0;
144 int r, donecr = 0, index = co->index;
146 /* Console access attempt outside of acceptable console range. */
147 if (index >= MAX_NR_HVC_CONSOLES)
150 /* This console adapter was removed so it is not usable. */
151 if (vtermnos[index] == -1)
154 while (count > 0 || i > 0) {
155 if (count > 0 && i < sizeof(c)) {
156 if (b[n] == '\n' && !donecr) {
165 r = cons_ops[index]->put_chars(vtermnos[index], c, i);
167 /* throw away characters on error
168 * but spin in case of -EAGAIN */
180 static struct tty_driver *hvc_console_device(struct console *c, int *index)
182 if (vtermnos[c->index] == -1)
189 static int __init hvc_console_setup(struct console *co, char *options)
191 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
194 if (vtermnos[co->index] == -1)
200 static struct console hvc_console = {
202 .write = hvc_console_print,
203 .device = hvc_console_device,
204 .setup = hvc_console_setup,
205 .flags = CON_PRINTBUFFER,
210 * Early console initialization. Precedes driver initialization.
212 * (1) we are first, and the user specified another driver
213 * -- index will remain -1
214 * (2) we are first and the user specified no driver
215 * -- index will be set to 0, then we will fail setup.
216 * (3) we are first and the user specified our driver
217 * -- index will be set to user specified driver, and we will fail
218 * (4) we are after driver, and this initcall will register us
219 * -- if the user didn't specify a driver then the console will match
221 * Note that for cases 2 and 3, we will match later when the io driver
222 * calls hvc_instantiate() and call register again.
224 static int __init hvc_console_init(void)
226 register_console(&hvc_console);
229 console_initcall(hvc_console_init);
231 /* callback when the kboject ref count reaches zero. */
232 static void hvc_port_destruct(struct tty_port *port)
234 struct hvc_struct *hp = container_of(port, struct hvc_struct, port);
237 spin_lock(&hvc_structs_lock);
239 spin_lock_irqsave(&hp->lock, flags);
240 list_del(&(hp->next));
241 spin_unlock_irqrestore(&hp->lock, flags);
243 spin_unlock(&hvc_structs_lock);
249 * hvc_instantiate() is an early console discovery method which locates
250 * consoles * prior to the vio subsystem discovering them. Hotplugged
251 * vty adapters do NOT get an hvc_instantiate() callback since they
252 * appear after early console init.
254 int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
256 struct hvc_struct *hp;
258 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
261 if (vtermnos[index] != -1)
264 /* make sure no no tty has been registered in this index */
265 hp = hvc_get_by_index(index);
267 tty_port_put(&hp->port);
271 vtermnos[index] = vtermno;
272 cons_ops[index] = ops;
274 /* reserve all indices up to and including this index */
275 if (last_hvc < index)
278 /* if this index is what the user requested, then register
279 * now (setup won't fail at this point). It's ok to just
280 * call register again if previously .setup failed.
282 if (index == hvc_console.index)
283 register_console(&hvc_console);
287 EXPORT_SYMBOL_GPL(hvc_instantiate);
289 /* Wake the sleeping khvcd */
293 wake_up_process(hvc_task);
295 EXPORT_SYMBOL_GPL(hvc_kick);
297 static void hvc_unthrottle(struct tty_struct *tty)
303 * The TTY interface won't be used until after the vio layer has exposed the vty
304 * adapter to the kernel.
306 static int hvc_open(struct tty_struct *tty, struct file * filp)
308 struct hvc_struct *hp;
312 /* Auto increments kref reference if found. */
313 if (!(hp = hvc_get_by_index(tty->index)))
316 spin_lock_irqsave(&hp->port.lock, flags);
317 /* Check and then increment for fast path open. */
318 if (hp->port.count++ > 0) {
319 spin_unlock_irqrestore(&hp->port.lock, flags);
322 } /* else count == 0 */
323 spin_unlock_irqrestore(&hp->port.lock, flags);
325 tty->driver_data = hp;
326 tty_port_tty_set(&hp->port, tty);
328 if (hp->ops->notifier_add)
329 rc = hp->ops->notifier_add(hp, hp->data);
332 * If the notifier fails we return an error. The tty layer
333 * will call hvc_close() after a failed open but we don't want to clean
334 * up there so we'll clean up here and clear out the previously set
335 * tty fields and return the kref reference.
338 tty_port_tty_set(&hp->port, NULL);
339 tty->driver_data = NULL;
340 tty_port_put(&hp->port);
341 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
343 /* Force wakeup of the polling thread */
349 static void hvc_close(struct tty_struct *tty, struct file * filp)
351 struct hvc_struct *hp;
354 if (tty_hung_up_p(filp))
358 * No driver_data means that this close was issued after a failed
359 * hvc_open by the tty layer's release_dev() function and we can just
360 * exit cleanly because the kref reference wasn't made.
362 if (!tty->driver_data)
365 hp = tty->driver_data;
367 spin_lock_irqsave(&hp->port.lock, flags);
369 if (--hp->port.count == 0) {
370 spin_unlock_irqrestore(&hp->port.lock, flags);
371 /* We are done with the tty pointer now. */
372 tty_port_tty_set(&hp->port, NULL);
374 if (hp->ops->notifier_del)
375 hp->ops->notifier_del(hp, hp->data);
377 /* cancel pending tty resize work */
378 cancel_work_sync(&hp->tty_resize);
381 * Chain calls chars_in_buffer() and returns immediately if
382 * there is no buffered data otherwise sleeps on a wait queue
383 * waking periodically to check chars_in_buffer().
385 tty_wait_until_sent_from_close(tty, HVC_CLOSE_WAIT);
387 if (hp->port.count < 0)
388 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
389 hp->vtermno, hp->port.count);
390 spin_unlock_irqrestore(&hp->port.lock, flags);
393 tty_port_put(&hp->port);
396 static void hvc_hangup(struct tty_struct *tty)
398 struct hvc_struct *hp = tty->driver_data;
405 /* cancel pending tty resize work */
406 cancel_work_sync(&hp->tty_resize);
408 spin_lock_irqsave(&hp->port.lock, flags);
411 * The N_TTY line discipline has problems such that in a close vs
412 * open->hangup case this can be called after the final close so prevent
413 * that from happening for now.
415 if (hp->port.count <= 0) {
416 spin_unlock_irqrestore(&hp->port.lock, flags);
420 temp_open_count = hp->port.count;
422 spin_unlock_irqrestore(&hp->port.lock, flags);
423 tty_port_tty_set(&hp->port, NULL);
427 if (hp->ops->notifier_hangup)
428 hp->ops->notifier_hangup(hp, hp->data);
430 while(temp_open_count) {
432 tty_port_put(&hp->port);
437 * Push buffered characters whether they were just recently buffered or waiting
438 * on a blocked hypervisor. Call this function with hp->lock held.
440 static int hvc_push(struct hvc_struct *hp)
444 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
446 if (n == 0 || n == -EAGAIN) {
450 /* throw away output on error; this happens when
451 there is no session connected to the vterm. */
455 if (hp->n_outbuf > 0)
456 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
463 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
465 struct hvc_struct *hp = tty->driver_data;
467 int rsize, written = 0;
469 /* This write was probably executed during a tty close. */
473 /* FIXME what's this (unprotected) check for? */
474 if (hp->port.count <= 0)
477 spin_lock_irqsave(&hp->lock, flags);
479 /* Push pending writes */
480 if (hp->n_outbuf > 0)
483 while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
486 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
489 hp->n_outbuf += rsize;
493 spin_unlock_irqrestore(&hp->lock, flags);
496 * Racy, but harmless, kick thread if there is still pending data.
505 * hvc_set_winsz() - Resize the hvc tty terminal window.
506 * @work: work structure.
508 * The routine shall not be called within an atomic context because it
513 static void hvc_set_winsz(struct work_struct *work)
515 struct hvc_struct *hp;
516 unsigned long hvc_flags;
517 struct tty_struct *tty;
520 hp = container_of(work, struct hvc_struct, tty_resize);
522 tty = tty_port_tty_get(&hp->port);
526 spin_lock_irqsave(&hp->lock, hvc_flags);
528 spin_unlock_irqrestore(&hp->lock, hvc_flags);
530 tty_do_resize(tty, &ws);
535 * This is actually a contract between the driver and the tty layer outlining
536 * how much write room the driver can guarantee will be sent OR BUFFERED. This
537 * driver MUST honor the return value.
539 static int hvc_write_room(struct tty_struct *tty)
541 struct hvc_struct *hp = tty->driver_data;
546 return hp->outbuf_size - hp->n_outbuf;
549 static int hvc_chars_in_buffer(struct tty_struct *tty)
551 struct hvc_struct *hp = tty->driver_data;
559 * timeout will vary between the MIN and MAX values defined here. By default
560 * and during console activity we will use a default MIN_TIMEOUT of 10. When
561 * the console is idle, we increase the timeout value on each pass through
562 * msleep until we reach the max. This may be noticeable as a brief (average
563 * one second) delay on the console before the console responds to input when
564 * there has been no input for some time.
566 #define MIN_TIMEOUT (10)
567 #define MAX_TIMEOUT (2000)
568 static u32 timeout = MIN_TIMEOUT;
570 #define HVC_POLL_READ 0x00000001
571 #define HVC_POLL_WRITE 0x00000002
573 int hvc_poll(struct hvc_struct *hp)
575 struct tty_struct *tty;
576 int i, n, poll_mask = 0;
577 char buf[N_INBUF] __ALIGNED__;
580 int written_total = 0;
582 spin_lock_irqsave(&hp->lock, flags);
584 /* Push pending writes */
585 if (hp->n_outbuf > 0)
586 written_total = hvc_push(hp);
588 /* Reschedule us if still some write pending */
589 if (hp->n_outbuf > 0) {
590 poll_mask |= HVC_POLL_WRITE;
591 /* If hvc_push() was not able to write, sleep a few msecs */
592 timeout = (written_total) ? 0 : MIN_TIMEOUT;
595 /* No tty attached, just skip */
596 tty = tty_port_tty_get(&hp->port);
600 /* Now check if we can get data (are we throttled ?) */
601 if (test_bit(TTY_THROTTLED, &tty->flags))
604 /* If we aren't notifier driven and aren't throttled, we always
605 * request a reschedule
607 if (!hp->irq_requested)
608 poll_mask |= HVC_POLL_READ;
610 /* Read data if any */
612 int count = tty_buffer_request_room(tty, N_INBUF);
614 /* If flip is full, just reschedule a later read */
616 poll_mask |= HVC_POLL_READ;
620 n = hp->ops->get_chars(hp->vtermno, buf, count);
622 /* Hangup the tty when disconnected from host */
624 spin_unlock_irqrestore(&hp->lock, flags);
626 spin_lock_irqsave(&hp->lock, flags);
627 } else if ( n == -EAGAIN ) {
629 * Some back-ends can only ensure a certain min
630 * num of bytes read, which may be > 'count'.
631 * Let the tty clear the flip buff to make room.
633 poll_mask |= HVC_POLL_READ;
637 for (i = 0; i < n; ++i) {
638 #ifdef CONFIG_MAGIC_SYSRQ
639 if (hp->index == hvc_console.index) {
640 /* Handle the SysRq Hack */
641 /* XXX should support a sequence */
642 if (buf[i] == '\x0f') { /* ^O */
643 /* if ^O is pressed again, reset
644 * sysrq_pressed and flip ^O char */
645 sysrq_pressed = !sysrq_pressed;
648 } else if (sysrq_pressed) {
649 handle_sysrq(buf[i]);
654 #endif /* CONFIG_MAGIC_SYSRQ */
655 tty_insert_flip_char(tty, buf[i], 0);
661 /* Wakeup write queue if necessary */
667 spin_unlock_irqrestore(&hp->lock, flags);
670 /* Activity is occurring, so reset the polling backoff value to
671 a minimum for performance. */
672 timeout = MIN_TIMEOUT;
674 tty_flip_buffer_push(tty);
680 EXPORT_SYMBOL_GPL(hvc_poll);
683 * __hvc_resize() - Update terminal window size information.
684 * @hp: HVC console pointer
685 * @ws: Terminal window size structure
687 * Stores the specified window size information in the hvc structure of @hp.
688 * The function schedule the tty resize update.
690 * Locking: Locking free; the function MUST be called holding hp->lock
692 void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
695 schedule_work(&hp->tty_resize);
697 EXPORT_SYMBOL_GPL(__hvc_resize);
700 * This kthread is either polling or interrupt driven. This is determined by
701 * calling hvc_poll() who determines whether a console adapter support
704 static int khvcd(void *unused)
707 struct hvc_struct *hp;
715 if (!cpus_are_in_xmon()) {
716 spin_lock(&hvc_structs_lock);
717 list_for_each_entry(hp, &hvc_structs, next) {
718 poll_mask |= hvc_poll(hp);
720 spin_unlock(&hvc_structs_lock);
722 poll_mask |= HVC_POLL_READ;
725 set_current_state(TASK_INTERRUPTIBLE);
730 if (timeout < MAX_TIMEOUT)
731 timeout += (timeout >> 6) + 1;
733 msleep_interruptible(timeout);
736 __set_current_state(TASK_RUNNING);
737 } while (!kthread_should_stop());
742 static int hvc_tiocmget(struct tty_struct *tty)
744 struct hvc_struct *hp = tty->driver_data;
746 if (!hp || !hp->ops->tiocmget)
748 return hp->ops->tiocmget(hp);
751 static int hvc_tiocmset(struct tty_struct *tty,
752 unsigned int set, unsigned int clear)
754 struct hvc_struct *hp = tty->driver_data;
756 if (!hp || !hp->ops->tiocmset)
758 return hp->ops->tiocmset(hp, set, clear);
761 #ifdef CONFIG_CONSOLE_POLL
762 int hvc_poll_init(struct tty_driver *driver, int line, char *options)
767 static int hvc_poll_get_char(struct tty_driver *driver, int line)
769 struct tty_struct *tty = driver->ttys[0];
770 struct hvc_struct *hp = tty->driver_data;
774 n = hp->ops->get_chars(hp->vtermno, &ch, 1);
782 static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
784 struct tty_struct *tty = driver->ttys[0];
785 struct hvc_struct *hp = tty->driver_data;
789 n = hp->ops->put_chars(hp->vtermno, &ch, 1);
794 static const struct tty_operations hvc_ops = {
798 .hangup = hvc_hangup,
799 .unthrottle = hvc_unthrottle,
800 .write_room = hvc_write_room,
801 .chars_in_buffer = hvc_chars_in_buffer,
802 .tiocmget = hvc_tiocmget,
803 .tiocmset = hvc_tiocmset,
804 #ifdef CONFIG_CONSOLE_POLL
805 .poll_init = hvc_poll_init,
806 .poll_get_char = hvc_poll_get_char,
807 .poll_put_char = hvc_poll_put_char,
811 static const struct tty_port_operations hvc_port_ops = {
812 .destruct = hvc_port_destruct,
815 struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
816 const struct hv_ops *ops,
819 struct hvc_struct *hp;
822 /* We wait until a driver actually comes along */
824 int err = hvc_init();
829 hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
832 return ERR_PTR(-ENOMEM);
834 hp->vtermno = vtermno;
837 hp->outbuf_size = outbuf_size;
838 hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
840 tty_port_init(&hp->port);
841 hp->port.ops = &hvc_port_ops;
843 INIT_WORK(&hp->tty_resize, hvc_set_winsz);
844 spin_lock_init(&hp->lock);
845 spin_lock(&hvc_structs_lock);
849 * see if this vterm id matches one registered for console.
851 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
852 if (vtermnos[i] == hp->vtermno &&
853 cons_ops[i] == hp->ops)
856 /* no matching slot, just use a counter */
857 if (i >= MAX_NR_HVC_CONSOLES)
862 list_add_tail(&(hp->next), &hvc_structs);
863 spin_unlock(&hvc_structs_lock);
867 EXPORT_SYMBOL_GPL(hvc_alloc);
869 int hvc_remove(struct hvc_struct *hp)
872 struct tty_struct *tty;
874 tty = tty_port_tty_get(&hp->port);
876 spin_lock_irqsave(&hp->lock, flags);
877 if (hp->index < MAX_NR_HVC_CONSOLES)
878 vtermnos[hp->index] = -1;
880 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
882 spin_unlock_irqrestore(&hp->lock, flags);
885 * We 'put' the instance that was grabbed when the kref instance
886 * was initialized using kref_init(). Let the last holder of this
887 * kref cause it to be removed, which will probably be the tty_vhangup
890 tty_port_put(&hp->port);
893 * This function call will auto chain call hvc_hangup.
901 EXPORT_SYMBOL_GPL(hvc_remove);
903 /* Driver initialization: called as soon as someone uses hvc_alloc(). */
904 static int hvc_init(void)
906 struct tty_driver *drv;
909 /* We need more than hvc_count adapters due to hotplug additions. */
910 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
916 drv->driver_name = "hvc";
918 drv->major = HVC_MAJOR;
919 drv->minor_start = HVC_MINOR;
920 drv->type = TTY_DRIVER_TYPE_SYSTEM;
921 drv->init_termios = tty_std_termios;
922 drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
923 tty_set_operations(drv, &hvc_ops);
925 /* Always start the kthread because there can be hotplug vty adapters
927 hvc_task = kthread_run(khvcd, NULL, "khvcd");
928 if (IS_ERR(hvc_task)) {
929 printk(KERN_ERR "Couldn't create kthread for console.\n");
930 err = PTR_ERR(hvc_task);
934 err = tty_register_driver(drv);
936 printk(KERN_ERR "Couldn't register hvc console driver\n");
941 * Make sure tty is fully registered before allowing it to be
942 * found by hvc_console_device.
949 kthread_stop(hvc_task);
957 /* This isn't particularly necessary due to this being a console driver
958 * but it is nice to be thorough.
960 static void __exit hvc_exit(void)
963 kthread_stop(hvc_task);
965 tty_unregister_driver(hvc_driver);
966 /* return tty_struct instances allocated in hvc_init(). */
967 put_tty_driver(hvc_driver);
968 unregister_console(&hvc_console);
971 module_exit(hvc_exit);