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>
43 #include <asm/uaccess.h>
45 #include "hvc_console.h"
51 * Wait this long per iteration while trying to push buffered data to the
52 * hypervisor before allowing the tty to complete a close operation.
54 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
57 * These sizes are most efficient for vio, because they are the
58 * native transfer size. We could make them selectable in the
59 * future to better deal with backends that want other buffer sizes.
64 #define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
66 static struct tty_driver *hvc_driver;
67 static struct task_struct *hvc_task;
69 /* Picks up late kicks after list walk but before schedule() */
70 static int hvc_kicked;
72 static int hvc_init(void);
74 #ifdef CONFIG_MAGIC_SYSRQ
75 static int sysrq_pressed;
78 /* dynamic list of hvc_struct instances */
79 static LIST_HEAD(hvc_structs);
82 * Protect the list of hvc_struct instances from inserts and removals during
85 static DEFINE_SPINLOCK(hvc_structs_lock);
88 * This value is used to assign a tty->index value to a hvc_struct based
89 * upon order of exposure via hvc_probe(), when we can not match it to
90 * a console candidate registered with hvc_instantiate().
92 static int last_hvc = -1;
95 * Do not call this function with either the hvc_structs_lock or the hvc_struct
96 * lock held. If successful, this function increments the kref reference
97 * count against the target hvc_struct so it should be released when finished.
99 static struct hvc_struct *hvc_get_by_index(int index)
101 struct hvc_struct *hp;
104 spin_lock(&hvc_structs_lock);
106 list_for_each_entry(hp, &hvc_structs, next) {
107 spin_lock_irqsave(&hp->lock, flags);
108 if (hp->index == index) {
110 spin_unlock_irqrestore(&hp->lock, flags);
111 spin_unlock(&hvc_structs_lock);
114 spin_unlock_irqrestore(&hp->lock, flags);
118 spin_unlock(&hvc_structs_lock);
124 * Initial console vtermnos for console API usage prior to full console
125 * initialization. Any vty adapter outside this range will not have usable
126 * console interfaces but can still be used as a tty device. This has to be
127 * static because kmalloc will not work during early console init.
129 static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
130 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
131 {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
134 * Console APIs, NOT TTY. These APIs are available immediately when
135 * hvc_console_setup() finds adapters.
138 static void hvc_console_print(struct console *co, const char *b,
141 char c[N_OUTBUF] __ALIGNED__;
142 unsigned i = 0, n = 0;
143 int r, donecr = 0, index = co->index;
145 /* Console access attempt outside of acceptable console range. */
146 if (index >= MAX_NR_HVC_CONSOLES)
149 /* This console adapter was removed so it is not usable. */
150 if (vtermnos[index] == -1)
153 while (count > 0 || i > 0) {
154 if (count > 0 && i < sizeof(c)) {
155 if (b[n] == '\n' && !donecr) {
164 r = cons_ops[index]->put_chars(vtermnos[index], c, i);
166 /* throw away chars on error */
177 static struct tty_driver *hvc_console_device(struct console *c, int *index)
179 if (vtermnos[c->index] == -1)
186 static int __init hvc_console_setup(struct console *co, char *options)
188 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
191 if (vtermnos[co->index] == -1)
197 static struct console hvc_con_driver = {
199 .write = hvc_console_print,
200 .device = hvc_console_device,
201 .setup = hvc_console_setup,
202 .flags = CON_PRINTBUFFER,
207 * Early console initialization. Precedes driver initialization.
209 * (1) we are first, and the user specified another driver
210 * -- index will remain -1
211 * (2) we are first and the user specified no driver
212 * -- index will be set to 0, then we will fail setup.
213 * (3) we are first and the user specified our driver
214 * -- index will be set to user specified driver, and we will fail
215 * (4) we are after driver, and this initcall will register us
216 * -- if the user didn't specify a driver then the console will match
218 * Note that for cases 2 and 3, we will match later when the io driver
219 * calls hvc_instantiate() and call register again.
221 static int __init hvc_console_init(void)
223 register_console(&hvc_con_driver);
226 console_initcall(hvc_console_init);
228 /* callback when the kboject ref count reaches zero. */
229 static void destroy_hvc_struct(struct kref *kref)
231 struct hvc_struct *hp = container_of(kref, struct hvc_struct, kref);
234 spin_lock(&hvc_structs_lock);
236 spin_lock_irqsave(&hp->lock, flags);
237 list_del(&(hp->next));
238 spin_unlock_irqrestore(&hp->lock, flags);
240 spin_unlock(&hvc_structs_lock);
246 * hvc_instantiate() is an early console discovery method which locates
247 * consoles * prior to the vio subsystem discovering them. Hotplugged
248 * vty adapters do NOT get an hvc_instantiate() callback since they
249 * appear after early console init.
251 int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
253 struct hvc_struct *hp;
255 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
258 if (vtermnos[index] != -1)
261 /* make sure no no tty has been registered in this index */
262 hp = hvc_get_by_index(index);
264 kref_put(&hp->kref, destroy_hvc_struct);
268 vtermnos[index] = vtermno;
269 cons_ops[index] = ops;
271 /* reserve all indices up to and including this index */
272 if (last_hvc < index)
275 /* if this index is what the user requested, then register
276 * now (setup won't fail at this point). It's ok to just
277 * call register again if previously .setup failed.
279 if (index == hvc_con_driver.index)
280 register_console(&hvc_con_driver);
284 EXPORT_SYMBOL_GPL(hvc_instantiate);
286 /* Wake the sleeping khvcd */
290 wake_up_process(hvc_task);
292 EXPORT_SYMBOL_GPL(hvc_kick);
294 static void hvc_unthrottle(struct tty_struct *tty)
300 * The TTY interface won't be used until after the vio layer has exposed the vty
301 * adapter to the kernel.
303 static int hvc_open(struct tty_struct *tty, struct file * filp)
305 struct hvc_struct *hp;
309 /* Auto increments kref reference if found. */
310 if (!(hp = hvc_get_by_index(tty->index)))
313 spin_lock_irqsave(&hp->lock, flags);
314 /* Check and then increment for fast path open. */
315 if (hp->count++ > 0) {
317 spin_unlock_irqrestore(&hp->lock, flags);
320 } /* else count == 0 */
322 tty->driver_data = hp;
324 hp->tty = tty_kref_get(tty);
326 spin_unlock_irqrestore(&hp->lock, flags);
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 spin_lock_irqsave(&hp->lock, flags);
340 spin_unlock_irqrestore(&hp->lock, flags);
342 tty->driver_data = NULL;
343 kref_put(&hp->kref, destroy_hvc_struct);
344 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
346 /* Force wakeup of the polling thread */
352 static void hvc_close(struct tty_struct *tty, struct file * filp)
354 struct hvc_struct *hp;
357 if (tty_hung_up_p(filp))
361 * No driver_data means that this close was issued after a failed
362 * hvc_open by the tty layer's release_dev() function and we can just
363 * exit cleanly because the kref reference wasn't made.
365 if (!tty->driver_data)
368 hp = tty->driver_data;
370 spin_lock_irqsave(&hp->lock, flags);
373 if (--hp->count == 0) {
374 /* We are done with the tty pointer now. */
376 spin_unlock_irqrestore(&hp->lock, flags);
378 /* Put the ref obtained in hvc_open() */
381 if (hp->ops->notifier_del)
382 hp->ops->notifier_del(hp, hp->data);
384 /* cancel pending tty resize work */
385 cancel_work_sync(&hp->tty_resize);
388 * Chain calls chars_in_buffer() and returns immediately if
389 * there is no buffered data otherwise sleeps on a wait queue
390 * waking periodically to check chars_in_buffer().
392 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
395 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
396 hp->vtermno, hp->count);
397 spin_unlock_irqrestore(&hp->lock, flags);
401 kref_put(&hp->kref, destroy_hvc_struct);
404 static void hvc_hangup(struct tty_struct *tty)
406 struct hvc_struct *hp = tty->driver_data;
413 /* cancel pending tty resize work */
414 cancel_work_sync(&hp->tty_resize);
416 spin_lock_irqsave(&hp->lock, flags);
419 * The N_TTY line discipline has problems such that in a close vs
420 * open->hangup case this can be called after the final close so prevent
421 * that from happening for now.
423 if (hp->count <= 0) {
424 spin_unlock_irqrestore(&hp->lock, flags);
428 temp_open_count = hp->count;
433 spin_unlock_irqrestore(&hp->lock, flags);
435 if (hp->ops->notifier_hangup)
436 hp->ops->notifier_hangup(hp, hp->data);
438 while(temp_open_count) {
441 kref_put(&hp->kref, destroy_hvc_struct);
446 * Push buffered characters whether they were just recently buffered or waiting
447 * on a blocked hypervisor. Call this function with hp->lock held.
449 static int hvc_push(struct hvc_struct *hp)
453 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
459 /* throw away output on error; this happens when
460 there is no session connected to the vterm. */
464 if (hp->n_outbuf > 0)
465 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
472 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
474 struct hvc_struct *hp = tty->driver_data;
476 int rsize, written = 0;
478 /* This write was probably executed during a tty close. */
485 spin_lock_irqsave(&hp->lock, flags);
487 /* Push pending writes */
488 if (hp->n_outbuf > 0)
491 while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
494 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
497 hp->n_outbuf += rsize;
501 spin_unlock_irqrestore(&hp->lock, flags);
504 * Racy, but harmless, kick thread if there is still pending data.
513 * hvc_set_winsz() - Resize the hvc tty terminal window.
514 * @work: work structure.
516 * The routine shall not be called within an atomic context because it
521 static void hvc_set_winsz(struct work_struct *work)
523 struct hvc_struct *hp;
524 unsigned long hvc_flags;
525 struct tty_struct *tty;
528 hp = container_of(work, struct hvc_struct, tty_resize);
530 spin_lock_irqsave(&hp->lock, hvc_flags);
532 spin_unlock_irqrestore(&hp->lock, hvc_flags);
536 tty = tty_kref_get(hp->tty);
537 spin_unlock_irqrestore(&hp->lock, hvc_flags);
539 tty_do_resize(tty, &ws);
544 * This is actually a contract between the driver and the tty layer outlining
545 * how much write room the driver can guarantee will be sent OR BUFFERED. This
546 * driver MUST honor the return value.
548 static int hvc_write_room(struct tty_struct *tty)
550 struct hvc_struct *hp = tty->driver_data;
555 return hp->outbuf_size - hp->n_outbuf;
558 static int hvc_chars_in_buffer(struct tty_struct *tty)
560 struct hvc_struct *hp = tty->driver_data;
568 * timeout will vary between the MIN and MAX values defined here. By default
569 * and during console activity we will use a default MIN_TIMEOUT of 10. When
570 * the console is idle, we increase the timeout value on each pass through
571 * msleep until we reach the max. This may be noticeable as a brief (average
572 * one second) delay on the console before the console responds to input when
573 * there has been no input for some time.
575 #define MIN_TIMEOUT (10)
576 #define MAX_TIMEOUT (2000)
577 static u32 timeout = MIN_TIMEOUT;
579 #define HVC_POLL_READ 0x00000001
580 #define HVC_POLL_WRITE 0x00000002
582 int hvc_poll(struct hvc_struct *hp)
584 struct tty_struct *tty;
585 int i, n, poll_mask = 0;
586 char buf[N_INBUF] __ALIGNED__;
589 int written_total = 0;
591 spin_lock_irqsave(&hp->lock, flags);
593 /* Push pending writes */
594 if (hp->n_outbuf > 0)
595 written_total = hvc_push(hp);
597 /* Reschedule us if still some write pending */
598 if (hp->n_outbuf > 0) {
599 poll_mask |= HVC_POLL_WRITE;
600 /* If hvc_push() was not able to write, sleep a few msecs */
601 timeout = (written_total) ? 0 : MIN_TIMEOUT;
604 /* No tty attached, just skip */
605 tty = tty_kref_get(hp->tty);
609 /* Now check if we can get data (are we throttled ?) */
610 if (test_bit(TTY_THROTTLED, &tty->flags))
613 /* If we aren't notifier driven and aren't throttled, we always
614 * request a reschedule
616 if (!hp->irq_requested)
617 poll_mask |= HVC_POLL_READ;
619 /* Read data if any */
621 int count = tty_buffer_request_room(tty, N_INBUF);
623 /* If flip is full, just reschedule a later read */
625 poll_mask |= HVC_POLL_READ;
629 n = hp->ops->get_chars(hp->vtermno, buf, count);
631 /* Hangup the tty when disconnected from host */
633 spin_unlock_irqrestore(&hp->lock, flags);
635 spin_lock_irqsave(&hp->lock, flags);
636 } else if ( n == -EAGAIN ) {
638 * Some back-ends can only ensure a certain min
639 * num of bytes read, which may be > 'count'.
640 * Let the tty clear the flip buff to make room.
642 poll_mask |= HVC_POLL_READ;
646 for (i = 0; i < n; ++i) {
647 #ifdef CONFIG_MAGIC_SYSRQ
648 if (hp->index == hvc_con_driver.index) {
649 /* Handle the SysRq Hack */
650 /* XXX should support a sequence */
651 if (buf[i] == '\x0f') { /* ^O */
652 /* if ^O is pressed again, reset
653 * sysrq_pressed and flip ^O char */
654 sysrq_pressed = !sysrq_pressed;
657 } else if (sysrq_pressed) {
658 handle_sysrq(buf[i], tty);
663 #endif /* CONFIG_MAGIC_SYSRQ */
664 tty_insert_flip_char(tty, buf[i], 0);
670 /* Wakeup write queue if necessary */
676 spin_unlock_irqrestore(&hp->lock, flags);
679 /* Activity is occurring, so reset the polling backoff value to
680 a minimum for performance. */
681 timeout = MIN_TIMEOUT;
683 tty_flip_buffer_push(tty);
690 EXPORT_SYMBOL_GPL(hvc_poll);
693 * __hvc_resize() - Update terminal window size information.
694 * @hp: HVC console pointer
695 * @ws: Terminal window size structure
697 * Stores the specified window size information in the hvc structure of @hp.
698 * The function schedule the tty resize update.
700 * Locking: Locking free; the function MUST be called holding hp->lock
702 void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
705 schedule_work(&hp->tty_resize);
707 EXPORT_SYMBOL_GPL(__hvc_resize);
710 * This kthread is either polling or interrupt driven. This is determined by
711 * calling hvc_poll() who determines whether a console adapter support
714 static int khvcd(void *unused)
717 struct hvc_struct *hp;
720 __set_current_state(TASK_RUNNING);
726 if (!cpus_are_in_xmon()) {
727 spin_lock(&hvc_structs_lock);
728 list_for_each_entry(hp, &hvc_structs, next) {
729 poll_mask |= hvc_poll(hp);
731 spin_unlock(&hvc_structs_lock);
733 poll_mask |= HVC_POLL_READ;
736 set_current_state(TASK_INTERRUPTIBLE);
741 if (timeout < MAX_TIMEOUT)
742 timeout += (timeout >> 6) + 1;
744 msleep_interruptible(timeout);
747 __set_current_state(TASK_RUNNING);
748 } while (!kthread_should_stop());
753 static const struct tty_operations hvc_ops = {
757 .hangup = hvc_hangup,
758 .unthrottle = hvc_unthrottle,
759 .write_room = hvc_write_room,
760 .chars_in_buffer = hvc_chars_in_buffer,
763 struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
764 const struct hv_ops *ops,
767 struct hvc_struct *hp;
770 /* We wait until a driver actually comes along */
772 int err = hvc_init();
777 hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
780 return ERR_PTR(-ENOMEM);
782 hp->vtermno = vtermno;
785 hp->outbuf_size = outbuf_size;
786 hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
788 kref_init(&hp->kref);
790 INIT_WORK(&hp->tty_resize, hvc_set_winsz);
791 spin_lock_init(&hp->lock);
792 spin_lock(&hvc_structs_lock);
796 * see if this vterm id matches one registered for console.
798 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
799 if (vtermnos[i] == hp->vtermno &&
800 cons_ops[i] == hp->ops)
803 /* no matching slot, just use a counter */
804 if (i >= MAX_NR_HVC_CONSOLES)
809 list_add_tail(&(hp->next), &hvc_structs);
810 spin_unlock(&hvc_structs_lock);
814 EXPORT_SYMBOL_GPL(hvc_alloc);
816 int hvc_remove(struct hvc_struct *hp)
819 struct tty_struct *tty;
821 spin_lock_irqsave(&hp->lock, flags);
822 tty = tty_kref_get(hp->tty);
824 if (hp->index < MAX_NR_HVC_CONSOLES)
825 vtermnos[hp->index] = -1;
827 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
829 spin_unlock_irqrestore(&hp->lock, flags);
832 * We 'put' the instance that was grabbed when the kref instance
833 * was initialized using kref_init(). Let the last holder of this
834 * kref cause it to be removed, which will probably be the tty_vhangup
837 kref_put(&hp->kref, destroy_hvc_struct);
840 * This function call will auto chain call hvc_hangup.
848 EXPORT_SYMBOL_GPL(hvc_remove);
850 /* Driver initialization: called as soon as someone uses hvc_alloc(). */
851 static int hvc_init(void)
853 struct tty_driver *drv;
856 /* We need more than hvc_count adapters due to hotplug additions. */
857 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
863 drv->owner = THIS_MODULE;
864 drv->driver_name = "hvc";
866 drv->major = HVC_MAJOR;
867 drv->minor_start = HVC_MINOR;
868 drv->type = TTY_DRIVER_TYPE_SYSTEM;
869 drv->init_termios = tty_std_termios;
870 drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
871 tty_set_operations(drv, &hvc_ops);
873 /* Always start the kthread because there can be hotplug vty adapters
875 hvc_task = kthread_run(khvcd, NULL, "khvcd");
876 if (IS_ERR(hvc_task)) {
877 printk(KERN_ERR "Couldn't create kthread for console.\n");
878 err = PTR_ERR(hvc_task);
882 err = tty_register_driver(drv);
884 printk(KERN_ERR "Couldn't register hvc console driver\n");
889 * Make sure tty is fully registered before allowing it to be
890 * found by hvc_console_device.
897 kthread_stop(hvc_task);
905 /* This isn't particularly necessary due to this being a console driver
906 * but it is nice to be thorough.
908 static void __exit hvc_exit(void)
911 kthread_stop(hvc_task);
913 tty_unregister_driver(hvc_driver);
914 /* return tty_struct instances allocated in hvc_init(). */
915 put_tty_driver(hvc_driver);
916 unregister_console(&hvc_con_driver);
919 module_exit(hvc_exit);